U.S. patent application number 10/383420 was filed with the patent office on 2003-12-18 for rapid conversion of metal-containing compounds to form metal oxides.
Invention is credited to Buechler, Karen J., Dunmead, Stephen, Johnson, Jacob A., Karpale, Kauko Johannes, Weimer, Alan W..
Application Number | 20030230169 10/383420 |
Document ID | / |
Family ID | 26879744 |
Filed Date | 2003-12-18 |
United States Patent
Application |
20030230169 |
Kind Code |
A1 |
Dunmead, Stephen ; et
al. |
December 18, 2003 |
Rapid conversion of metal-containing compounds to form metal
oxides
Abstract
A method of converting metal-containing compounds into a metal
or metal oxide by rapidly heating the metal-containing compound to
an elevated temperature to instigate conversion and holding the
metal-containing compound at the elevated temperature for a time
sufficient to effect formation of the metal or metal oxide is an
efficient and economical method of producing metals and metal
oxides.
Inventors: |
Dunmead, Stephen; (Raleigh,
NC) ; Karpale, Kauko Johannes; (Ulvila, FI) ;
Weimer, Alan W.; (Niwot, CO) ; Buechler, Karen
J.; (Westminster, CO) ; Johnson, Jacob A.;
(Roscoe, IL) |
Correspondence
Address: |
Gary R. Molnar, Esq.
Kalow & Springut LLP
19th Floor
488 Madison Avenue
New York
NY
10022
US
|
Family ID: |
26879744 |
Appl. No.: |
10/383420 |
Filed: |
March 7, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10383420 |
Mar 7, 2003 |
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09791275 |
Feb 22, 2001 |
|
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60184029 |
Feb 22, 2000 |
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60202305 |
May 5, 2000 |
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Current U.S.
Class: |
75/369 |
Current CPC
Class: |
C01G 53/04 20130101;
C01F 17/235 20200101; C01F 17/224 20200101; C01G 51/04 20130101;
B01J 8/12 20130101; C01P 2002/60 20130101; C01P 2004/50 20130101;
B22F 9/22 20130101; B22F 9/16 20130101; C01G 1/02 20130101; C01P
2006/60 20130101; C01B 13/18 20130101; B01J 2219/0277 20130101;
C01P 2006/10 20130101; C01P 2002/88 20130101; C01P 2004/64
20130101; B01J 23/70 20130101; B01J 37/16 20130101; B01J 2208/00557
20130101; C01G 3/02 20130101; B01J 8/087 20130101; B22F 9/30
20130101; C01P 2004/62 20130101; C01P 2006/80 20130101; B01J 37/082
20130101; C01P 2006/12 20130101; C01P 2004/61 20130101; B01J 37/12
20130101; B82Y 30/00 20130101; C01F 17/229 20200101; C01P 2006/11
20130101 |
Class at
Publication: |
75/369 |
International
Class: |
B22F 009/20 |
Claims
What is claimed is:
1. A method for converting a metal-containing compound to form the
metal or an oxide of the metal of the metal-containing compound,
comprising: heating the metal-containing compound at a rate of
between about 100.degree. C./second to about 100,000,000.degree.
C./second to an elevated temperature that makes the conversion of
the metal-containing compound thermodynamically favorable, and
holding the metal-containing compound at the elevated temperature
for a residence time sufficient to convert the metal-containing
compound into at least one product selected from the group
consisting of (i) the metal and (ii) oxides of the metal.
2. The method of claim 1, wherein the residence time is from about
0.1 to about 60 seconds.
3. The method of claim 1, wherein the conversion is by
decomposition.
4. The method of claim 1, wherein the conversion is by
oxidation.
5. The method of claim 1, wherein the conversion is by
reduction.
6. The method of claim 1, wherein the conversion is by
substantially simultaneous decomposition and reduction.
7. The method of claim 1, wherein the conversion is by
substantially simultaneous decomposition and oxidation.
8. The method of claim 1, wherein the residence time is from about
0.1 second to 30 seconds.
9. The method of claim 1, wherein the residence time is from about
0.1 second to 10 seconds.
10. The method of claim 1, wherein the heating rate is from about
100 to about 100,000,000.degree. C./second.
11. The method of claim 1, wherein the heating rate is from about
1,000 to about 1,000,000.degree. C./second.
12. The method of claim 1, wherein the heating rate is from about
10,000 to about 100,000.degree. C./second.
13. A method for converting a metal-containing compound to form the
metal or an oxide of the metal of the metal-containing compound,
comprising: heating the metal-containing compound at a rate of
between about 100.degree. C./second to about 100,000,000.degree.
C./second to an elevated temperature that makes the conversion of
the metal-containing compound thermodynamically favorable; holding
the metal-containing compound at the elevated temperature for a
residence time sufficient to convert a portion of the
metal-containing compound into at least one precursor selected from
the group consisting of (i) the metal and (ii) oxides of the metal;
heating the precursor to a second elevated temperature that makes
the conversion of the precursor thermodynamically favorable; and
holding the precursor at the second elevated temperature to convert
substantially all of the precursor into at least one product
selected from the group consisting of (i) the metal and (ii) oxides
of the metal.
14. A method for converting a metal-containing compound to form the
metal or an oxide of the metal of the metal-containing compound,
comprising:. heating the metal-containing compound at a rate of
between about 100.degree. C./second to about 100,000,000.degree.
C./second to an elevated temperature that makes the conversion of
the metal-containing compound thermodynamically favorable; holding
the metal-containing compound at the elevated temperature for a
residence time sufficient to convert the metal-containing compound
into at least one precursor selected from the group consisting of
(i) the metal and (ii) a precursor oxide of the metal; heating the
metal or precursor oxide to a second elevated temperature that
makes the conversion of the metal or precursor oxide
thermodynamically favorable; and holding the metal or precursor
oxide at the second elevated temperature to convert substantially
all of the metal or precursor oxide into the oxide of the
metal.
15. A method for converting a metal-containing compound to form the
metal of the metal-containing compound, comprising: heating the
metal-containing compound at a rate of between about 100.degree.
C./second to about 100,000,000.degree. C./second to an elevated
temperature that makes the conversion of the metal-containing
compound thermodynamically favorable; holding the metal-containing
compound at the elevated temperature for a residence time
sufficient to convert the metal-containing compound into at least
one precursor metal-containing compound; heating the precursor
metal-containing compound to a second elevated temperature that
makes the conversion of the precursor metal-containing
thermodynamically favorable; and holding the precursor
metal-containing compound at the second elevated temperature to
convert the precursor metal-containing compound into the metal.
16. The method of claim 1, wherein the metal-containing compound is
a metallic oxalate selected from the group consisting of the Group
VIII (Ni, Co, Fe), Group IVA (Sn, Pb), Group IVB (Hf), Group
VB(Ta), Group VIB (Cr, W), and combinations thereof, and the
heating of the metal-containing compound is in a substantially
non-oxidizing atmosphere.
17. The method of claim 16, wherein the at least one product is a
metal selected from the group consisting of nickel, cobalt, lead
and tin.
18. The method of claim 17, wherein the elevated temperature is
between approximately 600.degree. C. and 1300.degree. C.
19. The method of claim 17, wherein the residence time is from
about 0.1 second to about 30 minutes.
20. The method of claim 17, wherein the residence time is from
about 0.1 second to about 30 seconds.
21. The method of claim 17, wherein the residence time is from
about 0.1 second to about 10 seconds.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/184,029 filed Feb. 22, 2000, and U.S.
Provisional Application No. 60/202,305 filed May 5, 2000.
BACKGROUND OF THE INVENTION
[0002] The present invention provides an economical, rapid and
efficient method for making metal and metal oxide powders.
[0003] Metals and metal oxide powders enjoy a multitude of
applications. For example, metals and metal oxide powders are
suitable for use in the application fields of powder metallurgy,
catalysts, hardmetals, electrochemical devices (including
batteries, capacitors, photovoltaics, sensors and fuel cells),
metal matrix composites, chemicals (such as electroplating and as
raw materials for metal-organic compositions), magnetic
compositions, polymer fillers, pigments, optical absorbers, metal
injection-molding, electrical and magnetic shielding, display
materials, precursors for thin and thick film applications, thermal
spray, electronics (including conductors and dielectrics),
ceramics, integrated circuits, and brazing alloys, among
others.
[0004] Metals and metal oxide powders commonly are manufactured by
decomposing, oxidizing or reducing a metal carbonate, hydroxide or
oxide, or other metal-containing compound. The basic mechanisms and
kinetics of these reactions generally are well established.
Conventional conversion of metal-containing compounds to metals and
metal-oxides typically are carried out in pusher, strip-belt,
rotary, or fluidized bed reactors. To achieve complete conversion,
the reactants typically require a residence time on the order of
hours.
[0005] For example, the conversion of cobalt hydroxide by
decomposition and hydrogen reduction to form cobalt conventionally
requires a residence time of from one to two hours at a temperature
of 500 to 800.degree. C. in a strip belt or pusher reactor. The
conversion of cupric hydroxide to cupric oxide by decomposition and
oxidation in a strip-belt or pusher reactor requires a residence
time of from one to three hours at a temperature of 150 to
800.degree. C.
[0006] A variety of alternative methods of forming metals and metal
oxides from metal-containing compounds have been proposed. For
example, the formation of metallic powders by plasma vaporization
of inorganic compounds is disclosed in U.S. Pat. Nos. 5,788,738,
and 5,851,507.
[0007] Though plasma vaporization and similar methods are
scientifically interesting, the expense of required equipment and
the low production rates of these methods make them unsuitable for
large-scale commercial application.
[0008] It has been taught that carbothermal reduction of
metal-containing compounds to form metallic carbides and nitrides
may be conducted at rapid heating rates. For example, U.S. Pat. No.
5,194,234 describes a carbothermal reduction method of forming fine
powdered boron carbide by reacting a mixture of boric oxide or
hydrate and a carbon source at a temperature above about
1400.degree. C. and cooling the resultant product. In the method it
is preferred to heat the reaction mixture at a rate equal to or
exceeding 1000.degree. C./second.
[0009] U.S. Pat. Nos. 5,190,737 and 5,340,417 disclose methods of
preparing silicon carbide by carbothermal reduction involving
heating a mixture of a silica source and a carbon source at a
heating rate at least about 100.degree. C./second. U.S. Pat. Nos.
5,380,688 and 5,746,803 disclose methods employing rapid
carbothermal reduction which involve heating reactants at rates
from 100.degree. C. to 100,000,000.degree. C./second to from
metallic carbides. And U.S. Pat. No. 5,756,410 discloses a method
of forming metal carbonitrides which method includes heating
reactants at rates from 100.degree. C. to 100,000,000.degree.
C./second.
[0010] However, the effective use of rapid heating rates and short
residence times in the conversion of metal-containing compounds
into metals and metal oxides has not been shown.
SUMMARY OF THE INVENTION
[0011] This invention is a method for converting a metal-containing
compound into the metal or an oxide of the metal of the
metal-containing compound, which comprises heating the
metal-containing compound at a rate between about 100.degree.
C./second to about 100,000,000.degree. C./second to an elevated
temperature that makes conversion of the metal-containing compound
thermodynamically favorable, and holding the metal-containing
compound at the elevated temperature for a residence time
sufficient to substantially convert the metal-containing compound
into at least one product selected from the group consisting of (i)
the metal and (ii) oxides of the metal.
[0012] The present invention is based on the discovery that the
kinetics of conventional methods of converting metal-containing
compounds to metals and metal-oxides--such as decomposition,
oxidation and reduction--are much faster than previously known. By
rapidly heating a metal-containing compound, it has been found, the
compound may be converted to metal or metal-oxide in seconds or
fractions of seconds. The lengthy, hours--long reactor residence
times of convention have been overcome by the present
invention.
[0013] Thus, a method of producing metals and metal oxides
efficiently at a high production rate at relatively low cost is
provided by the present invention.
[0014] Typical reactions useful in the practice of this invention
for converting a metal-containing compound into the metal or an
oxide of the metal of the metal-containing compound include
decomposition, oxidation, reduction, substantially simultaneous
decomposition and reduction, and substantially simultaneous
decomposition and oxidation. Accordingly, embodiments of this
invention include the methods for (1) decomposing a
metal-containing compound to produce the metal or an oxide of the
metal of the metal-containing compound, (2) reducing a
metal-containing compound to produce the metal or an oxide of the
metal of the metal-containing compound, (3) oxidizing a
metal-containing compound to produce the metal or an oxide of the
metal of the metal-containing compound, (4) substantially
simultaneously decomposing and reducing a metal-containing compound
to produce the metal or an oxide of the metal of the
metal-containing compound, and (5) substantially simultaneous
decomposing and oxidizing a metal-containing compound to produce
the metal or an oxide of the metal of the metal-containing
compound; all of which methods comprise heating the
metal-containing compound at a rate of between about 100.degree.
C./second to about 100,000,000.degree. C./second to an elevated
temperature that makes conversion of the metal-containing compound
thermodynamically favorable and holding the metal-containing
compound at the elevated temperature for a residence time
sufficient to substantially convert the metal-containing compound
into at least one product selected from the group consisting of (i)
the metal and (ii) oxides of the metal.
[0015] In practicing the present invention, some metal and metal
oxides may be produced by a two-step process. In step one, the
metal-containing compound undergoes conversion to a "precursor"
metal-containing compound in which conversion is not substantially
complete. In step two (the finishing step), the product from step 1
is heated for a second time at a temperature sufficient to form the
final metal or metal oxide product. This two-step process is not
needed in all cases, but may be used when necessary or desired. The
second heat treatment may be carried out using the technology of
the present invention or may be carried out using conventional
methods.
[0016] In addition, the present invention may be practiced by first
converting a metal-containing compound to the metal ("precursor")
of the metal-containing compound, then in a second step, converting
the metal to an oxide of the metal. Also, the present invention may
be practiced by first converting a metal-containing compound to a
first (precursor) oxide of the metal of the metal-containing
compound, then in a second step converting the precursor metal
oxide into the metal or a second, different oxide of the metal of
the metal-containing compound.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a schematic of a vertical transport reactor that
is particularly useful for carrying out the present invention;
[0018] FIG. 2 is a graph illustrating the reaction rates for the
dissociation of nickel (Ni) oxalate into nickel metal, according to
the present invention, using a thermogravimetric analyzer (TGA) as
compared to the reaction rate of tungsten carbide (WC), silicon
carbide (SiC), and titanium carbide (TiC) synthesis by carbothermal
reduction and the reaction rate of silicon nitride
(Si.sub.3N.sub.4) synthesis by carbothermal nitridation; and
[0019] FIG. 3 is a graph illustrating the reaction rates for the
production of nickel (Ni), cobalt (Co), lead (Pb), and tin (Sn)
from their respective metal oxalates, according to the present
invention, using a thermogravimetric analyzer.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The method of the present invention may be employed suitably
to convert a metal-containing compound to produce the metal or an
oxide of the metal of the metal-containing compound. The mechanism
of conversion is preferably thermal decomposition, oxidation, or
reduction. Thermal decomposition can substantially accompany
oxidation or reduction, and thus these two (combination) reactions
are also preferred mechanisms for converting a metal-containing
compound into the metal or metal oxide in accordance with the
present invention.
[0021] The method may be employed using virtually any
metal-containing compound commercially available to form virtually
any commercially important metal or metal oxide. Due to the
commercial availability of compounds containing them, and to the
commercial market for them, it is preferred to employ the present
invention to manufacture the metals copper, iron, nickel, cobalt
(and other Group VIIIB metals); tungsten or titanium (and other
transition metals: tantalum, molybdenum, zirconium, hafnium,
vanadium, niobium and chromium), lithium, magnesium, zinc,
aluminum, gallium, germanium, indium, tin, lead, yttrium, scandium,
cerium, neodymium and lanthanum. Particularly preferred is the use
of the present invention to produce metal powders of cobalt,
nickel, copper and tungsten.
[0022] The method of this invention also may be employed to produce
metal oxides. Again because of their commercial value, it is
preferred to employ the invention to form oxides of copper,
tungsten and molybdenum. Particularly preferred is the manufacture
of cobalt oxide and nickel oxide.
[0023] The invention is suitable as well to produce a mixture of
two or more metals, a mixture of two or more metal oxides, a
mixture of a metal and one or more of its oxides, and a mixture of
a metal and an oxide of another metal. Preferred are lithium cobalt
dioxide and cobalt-nickel oxide.
[0024] Further, the method may be employed suitably to form alloys
of two or more metals, oxides of alloys, or a mixture of alloys.
Preferred are cobalt-chromium, cobalt-vanadium and
cobalt-iron-nickel, iron-nickel, bronze and brass.
[0025] The metal-containing compound may be any compound comprised
of at least the metal of the desired metal or metal oxide product.
Included, without limitation, are metal oxides, carbonates,
hydroxides, oxalates, acetates and salts. Among these, preferred
are hydroxides, carbonates and oxides.
[0026] Generally it is not preferred to use a metal halide as the
metal-containing compound in the present invention. Metal halides
such as CoCl.sub.2 may produce gaseous byproducts that are acidic
and pose environmental concerns.
[0027] Suitable metal-containing compounds also include compounds
containing two or more metals, including for example, nickel-cobalt
oxide and cobalt-chromium hydroxide, which are preferred.
[0028] The metal-containing compound also may comprise a mixture of
compounds having different metals when the desired product is a
mixture of metals, a metal alloy, a mixture of metal oxides or a
mixed metal oxide.
[0029] Accordingly, preferred metal-containing compounds for use in
(and the preferred conversions they undergo, in the present
invention include:
[0030] Carbonates:
3CoCO.sub.3+Air=Co.sub.3O.sub.4+CO/CO.sub.2
NiCO.sub.3+C.dbd.Ni+CO/CO.sub.2
3LiCO.sub.3+Co.sub.3O.sub.4.dbd.LiCoO.sub.2+CO/CO.sub.2
CoCO.sub.3+H.sub.2.dbd.Co+CO.sub.2+H.sub.2O
CuCO.sub.3+Air=CuO+CO.sub.2
Ni.sub.xCo.sub.(1-x)CO.sub.3+C.dbd.Ni.sub.xCo.sub.(1-x)+CO/CO.sub.2
[0031] Hydroxides:
3Co(OH).sub.2+Air=Co.sub.3O.sub.4+3H.sub.2O
Co(OH).sub.2+H.sub.2.dbd.Co+2H.sub.2O
Co(OH).sub.2+Inert=CoO+H.sub.2O
Cu(OH).sub.2.dbd.CuO+H.sub.2O
Cu(OH).sub.2+H.sub.2.dbd.Cu+2H.sub.2O
[0032] Oxalates:
3CoC.sub.2O.sub.4*2H.sub.2O+Air=Co.sub.3O.sub.4+6CO.sub.2+6H.sub.2O
CoC.sub.2O.sub.4*2H.sub.2O+H.sub.2.dbd.Co+2CO.sub.2+2H.sub.2O
CoC.sub.2O.sub.4*2H.sub.2O+Inert=Co+2CO.sub.2+2H.sub.2O
[0033] Salts:
Ammonium paratungstate+Air=WO.sub.3+NH.sub.3+H.sub.2O
[0034] Metals:
3Co+Air=Co.sub.3O.sub.4
Cu+Air=CuO/CuO.sub.2
Ni+Air=NiO
[0035] Oxides:
Co.sub.3O.sub.4+4H.sub.2=3Co+4H.sub.2O
CoO+H.sub.2.dbd.Co+H.sub.2O
NiO+H.sub.2.dbd.Ni+H.sub.2O
CuO+H.sub.2.dbd.Cu+H.sub.2O
Cu.sub.2O+H.sub.2=2Cu+H.sub.2O
Co.sub.3O.sub.4+3LiCO.sub.3=3LiCoO.sub.2+CO/CO.sub.2
Cu.sub.2O+Air=2CuO
[0036] The particles of the metal-containing compound are rapidly
and preferably individually heated rapidly to an elevated
temperature that makes conversion (e.g. decomposition, reduction or
oxidation) of the metal-containing compound into the metal or metal
oxide thermodynamically favorable.
[0037] The elevated temperature must be high enough such that the
decomposition, oxidation or reduction reaction is thermodynamically
favorable. The temperature also, is preferably less than the
melting point of any intended reaction product(s).
[0038] Thermodynamically minimum reaction temperatures for
decomposing, oxidizing and reducing a given metal-containing
compound to form a metal or metal oxide are readily calculatable.
The minimum elevated temperature of the rapid conversion process is
a temperature corresponding to a temperature where the Gibbs free
energy of the reaction to form the most stable metal-containing
compound employed in the reaction becomes negative.
[0039] For the purposes of the present invention, a thermal
gradient may be employed in the hot zone of the reactor, if in the
particular decomposition, oxidation or reduction it is determined
that it is beneficial to run the reactor with the temperature set
points not all being equal.
[0040] The heating rate for taking the metal-containing compound up
to the elevated temperature and instigating its conversion is
preferably at least on the order of about 100 to 10,000.degree. C.
per second and, optimally, on the order of about 10,000 to
1,000,000,000.degree. C. per second. Most preferably the heating
rate is from about 100,000 to 1,000,000.degree. C. per second.
[0041] In part, the residence time of the metal-containing compound
at the elevated temperature during the rapid thermal conversion
process depends upon the heating rate and elevated temperature.
Regardless of the temperature and heating rate, the residence time
must be long enough to convert at least a major portion (i.e.,
greater than about 50% by weight) of the metal-containing compound.
The residence time is preferably in the range of about 0.1 second
to about 60 seconds, more preferably about 0.2 second to about 10
seconds, most preferably about 0.2 second to about 5 seconds;
depending upon the heating method, heating rate, reaction
temperature and the ultimate particle size desired. At higher
temperatures, residence times substantially greater than 10 seconds
may produce undesired sintered aggregates rather than particulate
product. Whatever combination of reaction temperature, residence
time and heating rate is selected, however, it should be adequate
to convert the particular metal-containing compound into a product
composed mainly of a metal or metal oxide.
[0042] The three factors of elevated temperature, residence time
and heating rate also control the size of the particles obtained.
They do so by affecting both the nucleation rate for forming the
metal or metal oxide particles and the growth rate of these
particles, once formed. For example, presuming that the particles
are roughly spherical in shape and the conversion of starting
material to product occurs at a relatively constant volume rate,
the growth rate of the particles would be proportional to the cube
root of the residence time. In order to minimize the particle size
of the resulting metal or metal oxide powder, the elevated
temperature, heating rate and residence time must be selected to
yield a particle nucleation rate which is higher than, and
preferably significantly higher than, the particle growth rate.
[0043] The heating method and apparatus employable in the practice
of the present invention may be any type of heater and method known
in the art for heating particulates to the reaction temperatures at
heating rates in accordance with this invention. There are two
preferred methods for rapidly heating the particles of the
metal-containing compound. In one method, referred to herein as the
"drop" method, particulate metal-containing compound is dropped
into an already heated crucible that heats the particles at a rate
of between about 100.degree. C. per second to about 10,000.degree.
C. per second. In a second, more preferred, method, known herein as
the "entrainment method," the particles of the metal-containing
compound are entrained in an inert, oxidizing or reducing gas fed
into a vertical reaction tube (VTR) furnace maintained at the
reaction temperature, such as described in U.S. Pat. No. 5,110,565,
incorporated herein by reference. The heating rate in the
entrainment method is about 10,000.degree. C. per second to about
100,000,000.degree. C. per second. A. W. Weimer et al. describe the
heating rate determination in "Kinetics of Carbothermal Reduction
Synthesis of Beta Silicon Carbide," AIChE Journal, Vol. 39, No. 3
(March 1993), at pages 493-503. The teachings of this reference are
incorporated herein by reference.
[0044] In the drop method, an induction furnace is brought to the
desired reaction temperature and allowed to equilibrate for about
30 minutes. Aliquots of particles of the metal-containing compound
are dropped into a crucible in the hot zone of the furnace. The
extent of the reaction may be monitored, for example, by measuring
the reactant by product gas level in the crucible as a function of
time.
[0045] The aliquot is, following conversion to the product or
precursor, cooled as rapidly as possible back to a temperature
sufficient to minimize particle agglomeration and grain growth. The
drop method may be used as a predictor for results in the
entrainment method. In addition, thermogravimetric analysis (TGA)
can be used as a predictor of results for the entrainment and drop
methods. In TGA, the weight loss of the metal-containing compound
is followed as a function of time and temperature and the reaction
rate can be compared to those of other materials known to react
rapidly in the entrainment or drop modes.
[0046] In the preferred entrainment method, the metal-containing
compound has an average residence time in the vertical reaction
tube furnace of from about 0.1 to about 60 seconds, preferably from
about 0.2 to 10 seconds, most preferably from about 0.2 to 5
seconds. Because the heating rate is slower in the drop method, the
typical residence times in the drop method are on the order of 0.5
to 10 minutes, preferably from 0.5 to 5 minutes and more preferably
from 0.5 to 3 minutes, rather than seconds, as is the case in the
entrainment method.
[0047] The entrainment method involves the use of a vertical tube
reaction furnace (VTR) such as are disclosed in U.S. Pat. No.
5,110,565, previously incorporated by reference. Particles of the
metal-containing compound are placed into a feed hopper, which
allows a flowing gas, such as air, an inert gas, or an oxidizing or
reducing gas if the gas is to be the oxidizing or reducing agent in
an oxidation or reduction of the metal-containing compound, to
entrain the metal-containing compound and deliver it to the
furnace's reaction chamber as a dust cloud. The metal-containing
compound or compound mixture is immediately heated in the reaction
chamber at rates of between about 10,000.degree. C. to
100,000,000.degree. C. per second, while the average residence time
of powder in the furnace is on the order of seconds. The flowing
gas carries the powder product out of the reaction chamber hot zone
and into a cooling zone that rapidly cools the reacted powder below
its reaction temperature. The entrainment method is more preferred
than the drop method because the entrainment method is a more
practical mass production method.
[0048] The reactor disclosed in U.S. Pat. No. 5,110,565 comprises
four principal components of concern: a cooled reactant transport
member; a reactor chamber fed by the transport member; a heating
means for heating the reactor chamber and a cooling chamber fed by
the reactor chamber.
[0049] The transport member can be considered to be a conduit
disposed within a preferably annular gas-flow space that serves to
transport the particles into the reaction chamber. The transport
member is suitably maintained at a temperature below the melting
temperature of the metal-containing compound so as to prevent the
particles from coalescing either within, or near the exit of, the
transport member. Accordingly, the temperature of the transport
member should be sufficient to allow substantially all of the
particles to enter the reactor chamber as discrete particles.
[0050] The metal-containing compound is suitably fed into the
transport member by a powder feeding mechanism. The particular
powder feeding mechanism is not critical as long as it provides a
metered or controlled flow of the particles to the transport
member. The feeding mechanism, for example, can be a single screw
feeder, a twin screw feeder, a vibratory feeder, a rotary valve
feeder, a pneumatic (gas transport) feeder, or some other feeder of
conventional construction.
[0051] The reactor design and reactor capacity will determine the
maximum acceptable particulate feed rates. For example, merely by
way of illustration, for a reactor having a reaction zone volume of
2.16 cubic feet (ft.sup.3) (0.06 cubic meter (m.sup.3)) an
acceptable feed rate is from about 0.02 to about 0.5 kilogram per
minute (kgm). Acceptable feed rates will vary depending on the
particular reaction, reactor and reactor conditions but can be
determined readily without undue experimentation.
[0052] For the purposes of the present invention, it is important
that the feed powder (or powder feed mixture) enters the reactor in
the form of a dust cloud. Accordingly, after the powder exits the
powder feeder it must go through a disperser. Several methods of
dispersion are acceptable for the present invention. These methods
include, but are not limited to, gas dispersion nozzles (similar to
that described in U.S. Pat. No. 5,380,688), mechanical dispersers,
and ultrasonic dispersion. In most cases the powder feed needs to
be dispersed to agglomerates or individual particles less than 100
microns in diameter. The exact details, however, depend on the
reaction being carried out and the reactor conditions being used.
If the agglomerate or individual particle size is too large and the
residence time at temperature too short, the reaction will not be
complete.
[0053] The particles of the feed are entrained in a gas that may be
either an inert gas (e.g. argon or another noble gas), or a gas
that is compatible with the conversion to be carried out; that is,
either a gas that is a reactant or a gas that is a byproduct of the
conversion.
[0054] The entrainment gas is fed into the transport member at a
pressure and a flow rate sufficient to entrain the particulate
mixture and carry the particulate mixture into the reaction
chamber. Thus, the flow rate determines the residence time in the
reactor chamber. By way of illustration, the gas flow in the
transport member and via a gas flow around the perimeter of the
transport member are preferably at least 85 and 28 standard liters
per minute (slm), respectively, for a reactor having a reaction
zone volume of 2.16 cubic feet (ft.sup.3),(0.06 cubic meter
(m.sup.3)). The flow rates that are used also depend upon the
reactor temperature and reactant feed rate.
[0055] The present invention may be carried out in both co-current
and counter-current modes of operation. Counter-current flows may
be used to extend the residence time. In addition, for a particular
reaction it may be beneficial to introduce gas flows at various
places in the reactor. Also, for a particular reaction it may be
beneficial to introduce gas flows so that they are both co- and
counter-current and create turbulence in the reactor. Finally, it
may be beneficial in some cases to design the introduction of the
gas flows so that they create some specific gas flow pattern in the
reactor (e.g., helical).
[0056] The reactant particles enter the reaction zone in a form
approximating that of a well-dispersed dust cloud. The particles of
the mixture are heated almost instantaneously by gas convective and
conductive heat transfer, as well as by thermal radiation from the
walls defining the heated reaction zone. For particles having a
diameter less than 1000 microns, however, particle heating is
believed to be dominated by gas/particle conduction/convection
processes, rather than radiation. Internal particle conduction is
extremely rapid compared to surface heating, so that the particles
may be assumed to be isothermal with heating rates adequately
described for the mass by the surface heating characteristics. It
is on this basis that the preferred heating rate of about
10,000.degree. C. or higher per second is calculated. The actual
temperature within the reaction zone may be determined by optical
pyrometry or other suitable means.
[0057] The internal wall of the reaction zone of the reactor is
constructed of, or lined with, a material that does not react with
the particular metal-containing compound or compounds, or other
reactants, of the conversion process carried out, and that does not
melt or significantly deteriorate at the temperatures employed.
Depending on the reaction, the material may be graphite (or other
carbonaceous materials), metal (such as a nickel alloy), or ceramic
(such as aluminum oxide).
[0058] The gaseous flow that entrains the metal-containing compound
and transports it into the reaction zone also carries the product
powder out of the reaction zone. In general it may not be necessary
to employ a designed gas-solid separator to separate the product
from the entrainment gas. However, in some cases it may be
beneficial to include in the reactor a section that effectively
separates the product solids from the gas stream. This can be done
using several conventional methods, including but not limited to,
water traps, cyclones, porous metal or ceramic filters, bag filters
(i.e., bag houses), gravity settling, inertial impaction,
electrostatic precipitation, and scrubbers. Gas-solid separation is
important in both co-current and counter-current modes. Gas-solid
separation is of critical importance in the co-current mode because
the gas stream may carry the product away. This would effectively
limit the yield of the process and have a negative impact on the
overall economics.
[0059] In reactions where a condensable gaseous by-product is
produced (e.g., water vapor), it may be advantageous to design the
reactor in such a way as to perform the gas-solid separation above
the point at which condensation will occur (i.e., for water vapor
above 100.degree. C.).
[0060] Beneficially, the entrained dust cloud exits the reaction
zone and almost immediately enters a cooling zone. The cooling zone
quenches or rapidly cools the metal or metal oxide product below
its reaction temperature. Cooling rates within the cooling zone
beneficially approximate the heating rates within the reaction
zone. The walls of the cooling zone cool the entrainment gas and
rapidly remove any amount of heat retained by the product of the
rapid conversion. In the absence of this rapid cooling, reaction
with the particles could occur for an extended time, thereby
resulting in formation of undesirable agglomerates or larger grains
in the product. In addition, it may be important to rapidly cool
the product so as to (a) stop the reaction, (b) quench in a
specific phase, microstructure or particle size, (c) get the
product down to room temperature so that it is ready for further
processing or (d) for safety reasons. The actual cooling time
experienced will vary depending upon factors such as the particle
size, the physical configuration of the cooling zone and the exit
gas flow rate.
[0061] The cooling of the product may occur in an unheated (i.e.,
air-cooled) section of the reactor tube. However, forced cooling in
a water-jacketed section of the reactor may be employed. This
section beneficially has a significantly larger cross sectional
area than the reactor tube so that the product slows down.
[0062] The cooled particles are suitably collected and processed by
conventional technology. The product may be collected in either a
bin (tote) or other receiving vessel. In some cases, it is
important that the product not be directly exposed to air because
it will readily oxidize and/or is pyrophoric. In such cases it may
be important to slowly passivate the product by the controlled
introduction of oxygen (e.g., air/nitrogen mixes) combined (or not)
with cooling. This is particularly important in the production of
fine metal powders, but may also be important if the product is not
the most stable oxide (e.g., CoO rather than the more stable
Co.sub.3O.sub.4).
[0063] The product made by the reaction in the vertical transport
reactor may be a final product ready for commercial sale, or may
need further treatments. As an example, if the reaction is not
carried out to substantial completion in the VTR, then a second
heat treatment in a VTR or some other furnace is needed to complete
the reaction. ("Substantial completion" herein means at least about
50%, more preferably at least about 75%, and most preferred at
least about 90%, of the conversion is carried out to completion).
Other potential finishing processes include, but are not limited
to, passivation, reduction, oxidation, burnout of carbon or
organics, grinding, jet milling, classification, screening or
coating.
[0064] When the conversion is not substantially complete, the
conversion is substantially repeated. The product of the first
conversion (now referred to as the "precursor" in the second
conversion) is further converted in the second conversion to reach
the desired completion. Additional reactants, such as oxidizing or
reducing agents, may be employed in substantially the same manner
as in the first conversion to achieve substantially complete
conversion. The second conversion may be carried out in a VTR or
any other conventional apparatus.
[0065] Additionally, after the first conversion the precursor may
be subjected to a second conversion to form a different metal or
metal oxide. For example, after cobalt oxalate has been first
converted to cobalt oxide, the cobalt oxide may then be converted
to cobalt.
[0066] Although the drop method and entrainment method in
particular may be used for rapid conversion of metal-containing
compounds, any rapid heating method may be used to produce suitable
powder metals and metal oxides, so long as the rapidity of the
heating is maintained.
[0067] In one embodiment, the present invention is a low cost
process for synthesizing fine metallic particles or powders for
directly producing the fine metallic particles in the desired size
range of sub-micron to micron size for a desired purpose.
Basically, exposing metal-containing compounds--such as metal
oxalate salts--to extremely high heating rates with short residence
times in a non-oxidizing atmosphere causes the metal oxalate salts
to decompose leaving only the metal behind. With heating rates on
the order of 10,000.degree. C./second and minimized reaction times
less than ten (10) seconds, ultra fine metal particles are
formed.
[0068] Extremely high heating rates are achievable in a transport
tube reactor and allow the process to proceed as desired. The
reaction proceeds by a nucleation mechanism, thus the extremely
high heating rates are essential to the formation of the fine and
ultra-fine metal particles. More particularly, no (or minimal)
grinding of the fine metallic particles is required to reduce the
particle size or classification to eliminate larger particles.
Furthermore, because the product powders have sizes in the desired
range (not nano-size), residual oxygen contents are low and the
particle surfaces are passivated. These particles may be produced
using a high temperature, short residence time transport (or
aerosol) flow reactor so that rapid heating rates promote rapid
dissociation of precursors and limited residence times prevent
significant particle growth.
[0069] Due to the method of formation of the fine metallic
particles, the particle diameter can be specifically tailored to
meet very stringent specifications. More conventionally processed
powders using gaseous precursors (e.g. nickel chloride) produce
nano-sized fine metals that are not desirable for certain
electromagnetic radiation absorption applications. Other
conventional processes employing slower heating rate mechanisms
(e.g. pusher kilns, strip-belt furnaces, electric arc furnaces)
cannot limit residence time and the particles grow in size, even if
starting metallic oxalate precursors are used. In accordance with
the present invention, fine metallic powders produced by this
process are useful for a wide variety of purposes including, but
not limited to, electromagnetic shielding, semi-conductor
applications.
[0070] As before stated, the precursors to be dissociated include
various metal oxalates, carbonates, acetates, or hydroxides. For
example, with the process of the present invention, nickel oxalate
can be decomposed rapidly to produce fine sub-micron nickel powders
of high purity and with an oxygen content less than two (2 wt. %)
weight percent. In carrying out the dissociation according to the
present invention, the only byproduct is CO.sub.2 gas. Similar
dissociation reactions are also feasible for producing fine cobalt,
fine tin, and fine lead powders. Powders produced from these
precursors have higher purity than powders produced from more
conventionally processed gaseous homogenate precursors (e.g. nickel
chloride). Such product powders contain residual halogenated
species (e.g. chlorine) making them unsuitable for high purity
applications.
[0071] The reaction rates for dissociation of metal oxalates are
similar to those for various carbothermal reactions that have been
demonstrated in transport tube aerosol flow reactors. For example,
as illustrated in FIG. 2, heating rates of 0.5.degree. C./second
using a thermogravimetric analyzer indicate that the dissociation
of nickel oxalate at 375.degree. C. has a similar reaction rate to
that of tungsten carbide (WC) synthesis by carbothermal reduction
at 1350.degree. C. and is faster than silicon carbide (SiC)
synthesis by carbothermal reduction at 1515.degree. C. Both of
these carbothermal reactions are carried out in transport tube
reactors. FIG. 3 illustrates the reaction rates for the production
of nickel (Ni), cobalt (Co), lead (Pb), and tin (Sn) from their
respective metal oxalates using a thermogravimetric analyzer and a
heating rate of 0.5.degree. C./second.
[0072] The type of apparatus that can be used for carrying out the
process according to the present invention is similar to that
described by Weimer et al., U.S. Pat. No. 5,110,565 or Matovich,
U.S. Pat. Nos. 3,933,434, 4,042,334, or 4,044,117 (the disclosures
of which are incorporated herein by reference).
[0073] In the process according to one embodiment of the present
invention, a powdered precursor (e.g., nickel oxalate powder) is
loaded into a feeding assembly and is carried with inert gas (e.g.,
argon or nitrogen) through a heated transport tube. Heat from the
walls of the transport tube provides the energy required to
thermally dissociate the, precursor (e.g., nickel oxalate) to fine
metallic powder and carbon dioxide gas. The fine product powders
are collected in a bag house filter or some other type of fine
powder collection process. The tube walls are either heated
directly by electrical resistance (i.e., if it is graphite or
silicon carbide) or indirectly from heated electrodes that surround
the tube. The reaction tube can be fabricated from graphite, metal,
a refractory oxide material, or some other high temperature
material that can withstand the operating conditions. The gaseous
flow rates for the sweeping inert gas and the solids feed rates are
expected to be similar to those reported in the aforementioned
patents. The reactor residence times are expected to be between
approximately 0.1 and 10 seconds depending on the gas and solids
feed rates.
[0074] Moreover, the invention as disclosed herein, may be suitably
practiced in the absence of the specific elements which are
disclosed herein.
[0075] The metals and metal oxide powders formed by the practice of
the present invention are suitable for use in all fields in which
metals and metal oxide powders produced by conventional processes
are employed. The metals and metal oxide powders resulting from the
present invention are suitable for use especially in the
application fields of powder metallurgy, catalysts, hard metals,
electrochemical devices (including batteries, capacitors,
photovoltaics, sensors and fuel cells), polymer fillers, pigments,
optical absorbers, display materials, precursors for thin and thick
film applications, magnetic compositions, metal injection-molding,
thermal spray, electronics (including conductors and dielectrics),
ceramics, chemicals (such as electroplating and raw materials for
forming metal-organic compositions), integrated circuits, metal
matrix composites, magnetic and electric shielding, and brazing
alloys, among others.
[0076] The following examples are solely for illustrative purposes
and are not to be construed as limiting the scope of the present
invention.
EXAMPLES
[0077] The following examples 1-37 all were conducted in a vertical
transport reactor (VTR). FIG. 1 is a schematic of the reactor used.
The reactor (1) had at its core a furnace (2) with a heated zone
that was 6 inches in diameter and 5 foot long. The reaction tube
(3) was constructed out of a high-temperature, nickel-based alloy,
and extended approximately 3 feet above and 3 feet below the
furnace supplying the heat. The furnace had three independently
controlled heating zones (4A, 4B and 4C) capable of producing a
maximum temperature of 1200.degree. C. The feed material was fed
into the top of the vertical transport reactor via a screw feeder
(5). After exiting the screw feeder, the powdered feed was
mechanically dispersed by a disperser (6). The dispersed powder
then was sifted through a 75-micron screen (7) to remove large
agglomerates. The powder mixture fell through the furnace hot zone
and a cooling zone (8) and was collected in a product collection
can (9) at the bottom of the reactor.
[0078] The reactor was run in both co-current (powder and gas
flowing downward) and counter-current (powder flowing downward and
gas flowing upward) modes. The mode of operation was selected based
upon the chemistry involved and residence time needed. In either
mode of operation, the off gasses (by products) were then bubbled
through a water trap (10) and burned using a propane burner. In the
case of Examples 1-37 given below, all three heating zones were run
at the same temperature.
[0079] The reactor used in Examples 1-37 may be varied in
accordance with known engineering principles and the present
disclosure to carry out the present invention.
[0080] The products of Examples 1-37 were analyzed to determine
their content, crystallite size, surface area, and density. Cobalt
content by volume (Co [%]) in cobalt oxide or cobalt was measured
by a titration method based on the ISO 9389: 1989 (E)--standard
(Determination of cobalt content--Potentiometric titration method
with potassium hexacyanoferrate(III) (K.sub.3[Fe(CN).sub.6]
solution, 223.35 grams per 10 litres). The method involves
potentiometric titration using a platinum electrode. An extra
amount of known potassium ferrisyanide solution was back titrated
by a known Co standard solution in an alkalic matrix with ammonium
citrate as a buffer.
[0081] Cobalt monoxide content by volume (CoO [%]) in cobalt oxide
was measured by X-ray diffraction. The x-ray diffraction unit was
calibrated with known samples by the addition method. The
calibration and the measurement were based on the cobalt oxide and
cobalt monoxide peak area ratios.
[0082] Cobalt metal content by volume (Metallic Co [%]) also was
measured by X-ray diffraction. The x-ray diffraction unit was
calibrated with known samples by the addition method. The
calibration and the measurement were based on the cobalt monoxide
and cobalt metal peak area ratios.
[0083] Copper content in copper oxide was measured by a titration
method based on a complexometric titration using a copper
electrode. The extra amount of a known EDTA solution was titrated
by a known standard Cu solution in an alkalic matrix with ammonium
chloride as a buffer.
[0084] Crystallite size was measured by X-ray line broadening of
the peaks at 220 (Crystallite size [220]) and at 311 (Crystallite
size [311]). The full widths at half maximum height of the
mentioned peaks were measured and the crystallite size was
calculated based on the Sherrit equation.
[0085] Surface area was measured by BET based on N.sub.2 adsorption
on the surface following the ASTM D4567 standard. The analysis
gives the surface area in m.sup.2/gram.
[0086] Apparent density (AD) was measured by the ASTM B213
standard. The measurement gives the loose density of the product in
grams/cc.
[0087] Tap density (TD) was measured by the ASTM B527 standard in
which the product sample is tapped to give packed density in
grams/cc.
[0088] Decomposition/Oxidation of Cobalt Hydroxide
Example 1
[0089] The reactor described above was used in an attempt to carry
out the general reaction shown below.
3Co(OH).sub.2+airCo.sub.3O.sub.4+3H.sub.2O (vapor) (Reaction 1)
[0090] The Co(OH).sub.2 feed material was obtained from OMG Kokkola
Chemicals Oy (Kokkola, Finland). This particular material (Lot
Number C04-9207) had an average agglomerate size of 1 micron. The
Co(OH).sub.2 feed material is pink or light red in color. The feed
material was fed into the vertical transport reactor at a rate of
1.7 kg per hour. The gas medium used for this particular run was
air flowing at 20 scfh (standard cubic feet per hour) in a
co-current mode. The temperatures for all three zones of the VTR
were controlled at 500.degree. C. Under these conditions the
residence time is estimated to be 4-6 seconds. After 30 minutes had
elapsed the feeder was shut off and the product was taken out of
the product collection can. The product collection can contained
powder and also water that had condensed from the off gases.
Approximately 0.67 kg of dried product was obtained. From a visual
standpoint, the product was a fine black powder (i.e.,
Co.sub.3O.sub.4). These results indicate that desired reaction
(Reaction 1) occurred.
Example 2
[0091] Example 1 was repeated except that the temperatures on all
three zones of the VTR were increased to 600.degree. C. Under these
conditions the residence time was estimated to be 4-6 seconds. The
dried product that was collected was approximately 0.65 kg and it
was again a fine black (Co.sub.3O.sub.4) powder.
Example 3
[0092] Example 1 was repeated except that the temperatures on all
three zones of the VTR were increased to 700.degree. C. Under these
conditions the residence time was estimated to be 4-6 seconds. The
dried product that was collected was approximately 0.65 kg and, as
was the case in Examples 1 and 2, above, it was a fine black
powder.
Example 4
[0093] Example 1 was repeated except that the temperatures on all
three zones of the VTR were increased to 800.degree. C. and the
runtime was decreased to 18 minutes. Under these conditions the
residence time is estimated to be 4-6 seconds. The dried product
that was collected was approximately 0.40 kg of a fine black
powder.
Example 5
[0094] Example 1 was repeated except that the temperatures on all
three zones of the VTR were increased to 700.degree. C. and the gas
flow was switched to the counter-current mode. Under these
conditions the residence time was estimated to be 6-8 seconds. The
product that was collected was entirely dry (i.e., the by-product
water vapor had been carried off in the off-gases at the top of the
reactor). Approximately 0.66 kg of product was collected. The
product was a fine black powder (i.e., Co.sub.3O.sub.4).
Example 6
[0095] Example 5 was repeated except that the temperatures on all
three zones of the VTR were increased to 600.degree. C. Under these
conditions the residence time was estimated 6-8 seconds.
Approximately 0.64 kg of a dry, fine black powder was
collected.
Example 7
[0096] Example 5 was repeated except that the temperatures on all
three zones of the VTR were decreased to 500.degree. C. Under these
conditions the residence time was estimated to be 6-8 seconds.
Approximately 0.63 kg of a dry, fine black powder was
collected.
[0097] A summary of the run conditions for the
Decomposition/Oxidation of Cobalt Hydroxide examples 1-7 is given
below in Table 1.
1TABLE 1 Feed Rate Gas Gas Flow Temp. Example Feed (kg/hr) Phase
Rate (scfh) Mode (.degree. C.) 1 Co(OH).sub.2 1.7 Air 20 Co-current
500 2 Co(OH).sub.2 1.7 Air 20 Co-current 600 3 Co(OH).sub.2 1.7 Air
20 Co-current 700 4 Co(OH).sub.2 1.7 Air 20 Co-current 800 5
Co(OH).sub.2 1.7 Air 20 Counter-current 700 6 Co(OH).sub.2 1.7 Air
20 Counter-current 600 7 Co(OH).sub.2 1.7 Air 20 Counter-current
500
[0098] A summary of the experimental results for the
Decomposition/Oxidation of t Hydroxide examples 1-7 is given below
in Table 2.
2TABLE 2 Run Time Product Collected Product Product Example (min.)
(kg) Color Composition 1 30 0.67 Black Co.sub.3O.sub.4 2 30 0.65
Black Co.sub.3O.sub.4 3 30 065 Black Co.sub.3O.sub.4 4 18 0.40
Black Co.sub.3O.sub.4 5 30 0.66 Black Co.sub.3O.sub.4 6 30 0.64
Black Co.sub.3O.sub.4 7 30 0.60 Black Co.sub.3O.sub.4
[0099] A summary of analyses on the Co.sub.3O.sub.4 products
collected from the Decomposition/Oxidation of Cobalt Hydroxide
examples 1-7 is given below in Table 3.
3TABLE 3 Surface Crystallite Crystallite Metallic Area AD TD Size
Size Example Co [%] CoO [%] Co [%] (m.sup.2/g) (g/cc) (g/cc) [220]
in nm [311] in nm 1 71.0 -- -- 30.5 0.71 1.03 -- -- 2 71.2 -- --
28.1 0.75 1.10 -- -- 3 70.2 -- -- 25.7 0.79 1.15 -- -- 4 71.6 -- --
22.6 1.00 1.48 -- -- 5 73.5 2 <1 8.2 0.99 1.42 50 47 6 72.5
<1 1 12.4 0.85 1.21 35 32.5 7 72.5 <1 <1 18.6 0.80 1.13 23
21
[0100] Decomposition/Reduction of Cobalt Hydroxide
Example 8
[0101] The reactor described above was used to carry out the
general reaction shown below.
Co(OH).sub.2+H.sub.2Co+2H.sub.2O (vapor) (Reaction 2)
[0102] The Co(OH).sub.2 feed material was the same as in Example 1.
The feed material was fed into the vertical transport reactor at a
rate of 1.7 kg per hour. The gas medium used for this particular
run was hydrogen flowing at 50 scfh in a co-current mode. The
temperatures for all three zones of the VTR were controlled at
800.degree. C. After 15 minutes had elapsed the feeder was shut off
and the product was taken out of the product collection can. The
product collection can contained powder and also water that had
condensed from the off gases. Approximately 0.25 kg of dried
product was obtained. From a visual standpoint, the product was a
fine gray powder (i.e., Co). These results indicate that desired
reaction (Reaction 2) occurred.
Example 9
[0103] Example 8 was repeated except the temperatures on all three
zones of the VTR were decreased to 700.degree. C. The dried product
collected was approximately 0.23 kg and it was again a fine gray
powder.
Example 10
[0104] Example 8 was repeated except the temperatures on all three
zones of the VTR were decreased to 400.degree. C. The dried product
that was collected was approximately 0.30 kg and it was a fine
blackish-gray powder. The results from this example indicate that
the reaction was not entirely complete. This may have been due to
the fact that either the temperature was too low, the residence
time at that temperature was too short, or the degree of dispersion
was inadequate for these particular conditions.
Example 11
[0105] Example 8 was repeated except the temperatures on all three
zones of the VTR were decreased to 500.degree. C. and the hydrogen
gas flow was run in a counter-current mode. The product that was
collected was entirely dry (i.e., the by-product water vapor had
been carried off in the off-gases at the top of the reactor).
Approximately 0.24 kg of product was collected. The product was a
fine blackish-gray powder. These results indicated that the
reaction was not entirely complete.
Example 12
[0106] Example 11 was repeated except the temperatures on all three
zones of the VTR were increased to 600.degree. C. Approximately
0.25 kg of dry product was collected. The product was a fine gray
powder (i.e., Co).
Example 13
[0107] Example 11 was repeated except the temperatures on all three
zones of the VTR were increased to 700.degree. C. Approximately
0.25 kg of dry product was collected. The product was a fine gray
powder (i.e., Co). The results from Examples 11 thru 13 show that
it is feasible to make a cobalt powder by rapid decomposition of a
metal hydroxide via reaction 2.
[0108] A summary of the run conditions for the
Decomposition/Reduction of Cobalt Hydroxide examples 8-13 is given
below in Table 4.
4TABLE 4 Feed Rate Gas Gas Flow Temp. Example Feed (kg/hr) Phase
Rate (scfh) Mode (.degree. C.) 8 Co(OH).sub.2 1.7 Hydrogen 50
Co-current 800 9 Co(OH).sub.2 1.7 Hydrogen 50 Co-current 700 10
Co(OH).sub.2 1.7 Hydrogen 50 Co-current 400 11 Co(OH).sub.2 1.7
Hydrogen 50 Counter-current 500 12 Co(OH).sub.2 1.7 Hydrogen 50
Counter-current 600 13 Co(OH).sub.2 1.7 Hydrogen 50 Counter-current
700
[0109] A summary of the experimental results for the
Decomposition/Reduction of Cobalt Hydroxide examples 8-13 is given
below in Table 5.
5TABLE 5 Run Time Product Collected Product Product Example (min.)
(kg) Color Composition 8 30 0.67 Gray Co 9 30 0.65 Gray Co 10 30
0.65 Blackish-Gray Co/Co.sub.3O.sub.4 11 18 0.40 Blackish-Gray
Co/Co.sub.3O.sub.4 12 30 0.66 Gray Co 13 30 0.64 Gray Co
[0110] A summary of analyses on the Co products collected from
examples 8-13 is given below in Table 6.
6TABLE 6 Surface Conversion Area Oxygen Carbon Sulfur Example Co
[%] [%] (m.sup.2/g) [%] [ppm] [ppm] 8 76.2 39 2.7 -- -- -- 9 -- --
-- -- -- -- 10 77.1 42 -- -- -- -- 11 -- -- 3.4 -- -- -- 12 -- --
1.9 -- -- -- 13 -- -- 1.1 -- -- --
[0111] Decomposition/Oxidation of Copper Hydroxide
Example 14
[0112] The reactor described above was used to carry out the
general reaction shown below.
Cu(OH).sub.2+airCuO+2H.sub.2O (vapor) (Reaction 3)
[0113] The Cu(OH).sub.2 feed material was obtained from Aldrich
Chemical Company, Milwaukee, Wis. and had an approximate
agglomerate size of 20 microns. The Cu(OH).sub.2 is blue in color.
The feed material was fed into the vertical transport reactor at a
rate of 1.16 kg per hour. The gas medium was air flowing at 20 scfh
in a counter-current mode. The temperatures for all three zones of
the VTR were controlled at 300.degree. C. Under these conditions
the residence time was estimated to be 2-4 seconds. After 30
minutes had elapsed the feeder was shut off and the product was
taken out of the product collection can. The dry product collected
was mostly a fine black powder (i.e., CuO) with a few larger
(.about.75 micron) chunks of unreacted blue hydroxide.
Approximately 0.42 kg of product was obtained. These results
indicate that desired reaction (Reaction 3) occurred. The larger
chunks of unreacted hydroxide indicate that the dispersion may need
to be improved somewhat for this reaction under these
conditions.
Example 15
[0114] Example 14 was repeated except the temperature in all three
zones of the VTR was increased to 500.degree. C. Approximately 0.40
kg of dry product was collected. The product collected was nearly
identical to that produced in Example 14, except for the fact that
the concentration of the unreacted hydroxide was lower.
Example 16
[0115] Example 15 was repeated except the counter-current gas flow
was increased to 40 scfh. This yielded a slightly longer residence
time than in Example 14 or 15. Approximately 0.43 kg of dry product
was collected. The product collected was nearly identical to that
produced in Example 15.
Example 17
[0116] Example 16 was repeated except the temperature of all three
zones of the VTR was increased to 700.degree. C. Approximately 0.41
kg of dry product was collected. The product collected was nearly
identical to that produced in Example 16 except that the
concentration of the unreacted hydroxide was even lower.
Example 18
[0117] Example 16 was repeated except the temperature of all three
zones of the VTR was increased to 800.degree. C. and the reaction
was run for only 15 minutes. Approximately 0.19 kg of dry product
was collected. The product collected was nearly identical to that
produced in Example 17 except that the concentration of the
unreacted hydroxide was even lower.
[0118] The results of Examples 14 to 18 indicate that the
Cu(OH).sub.2 needs to be well dispersed and that the tendency to
have large unreacted agglomerates decreases with increasing
temperature.
[0119] A summary of the run conditions for the
Decomposition/Oxidation of Copper Hydroxide examples 14-18 is given
below in Table 7.
7TABLE 7 Feed Rate Gas Gas Flow Temp. Example Feed (kg/hr) Phase
Rate (scfh) Mode (.degree. C.) 14 Cu(OH).sub.2 1.16 Air 20
Counter-current 300 15 Cu(OH).sub.2 1.16 Air 20 Counter-current 500
16 Cu(OH).sub.2 1.16 Air 40 Counter-current 500 17 Cu(OH).sub.2
1.16 Air 40 Counter-current 700 18 Cu(OH).sub.2 1.16 Air 40
Counter-current 800
[0120] A summary of the experimental results for the
Decomposition/Reduction of Copper Hydroxide examples 14-18 is given
below in Table 8.
8 TABLE 8 Product Collected Product Product Example (kg) Color
Composition 14 0.42 Black CuO 15 0.40 Black CuO 16 0.43 Black CuO
17 0.41 Black CuO 18 9.19 Black CuO
[0121] A summary of analyses on the CuO products collected from the
Decomposition/Reduction of Copper Hydroxide examples 14-18 is given
below in Table 9.
9 TABLE 9 Surface Area Example Cu [%] (m.sup.2/g) AD (g/cc) 14 74.2
60.9 1.0 15 75.0 32.7 1.1 16 76.5 32.8 1.1 17 77.2 15.1 1.2 18 78.0
8.2 1.2
[0122] Decomposition/Reduction of Copper Hydroxide
Example 19
[0123] Example 17 was repeated except the gas was changed to
hydrogen. Approximately 0.29 kg of dry product was collected. The
product was bright copper colored (i.e., Cu Powder) when first
removed from the product collection can, but readily turned a
purplish color after being exposed to air (i.e., Cu.sub.2O). These
results show the present invention can be used to make Copper
powder via the reaction shown below.
Cu(OH).sub.2+H.sub.2.dbd.Cu+2H.sub.2O (vapor) (Reaction 4)
[0124] Oxidation of Cobalt Powder
Example 20
[0125] The reactor described above was used to carry out the
general reaction shown below.
3Co+AirCo.sub.3O.sub.4 (Reaction 5)
[0126] The Co powder feed material was obtained from OMG Kokkola
Chemicals Oy Kokkola, Finland) and had an approximate agglomerate
size of 6 microns and an ultimate crystallite size of 0.8 microns.
The cobalt powder was gray in color and the lot number was
P32-9207. The feed material was fed into the vertical transport
reactor at a rate of 1.1 kg per hour. The gas medium used was air
flowing at 100 scfh in a counter-current mode. The temperatures for
all three zones of the VTR were controlled at 900.degree. C. Under
these conditions the residence time was estimated to be 2-4
seconds. After 30 minutes had elapsed the feeder was shut off and
the product can was opened. As soon as air hit the product, it
began to further oxidize and burn. These results indicate that
either the residence time was too short or the temperature too low
to complete this oxidation reaction. Higher temperatures and/or
longer residence times would allow this reaction to be
completed.
[0127] Reduction of Cobalt Oxide
Example 21
[0128] The reactor described above was used to carry out the
general reaction shown below.
Co.sub.3O.sub.4+4H.sub.2=3Co+4H.sub.2O (vapor) (Reaction 6)
[0129] The Co.sub.3O.sub.4 powder feed material was obtained from
OMG Kokkola Chemicals Oy (Kokkola, Finland). This particular
material had a surface area of 0.9 m.sup.2/g and had an approximate
agglomerate size of 4 microns. The powder was black in color and
the lot number was C12-9354-2. The feed material was fed into the
vertical transport reactor at a rate of 1.43 kg per hour. The gas
medium used for this particular run was hydrogen flowing at 50 scfh
in a counter-current mode. The temperatures for all three zones of
the VTR were controlled at 400.degree. C. Under these conditions
the residence time was estimated to be 2-4 seconds. After 20
minutes had elapsed the feeder was shut off and the product was
removed from the collection can. Approximately 0.43 kg of fine
black powder (i.e., Co.sub.3O.sub.4) was recovered.
Example 22
[0130] Example 21 was repeated except the temperature in all three
zones of the VTR was increased to 600.degree. C. Approximately 0.40
kg of a fine blackish-gray powder (i.e., Co.sub.3O.sub.4 and Co)
was recovered.
Example 23
[0131] Example 22 was repeated except the counter-current hydrogen
gas flow was increased to 100 scfh. Approximately 0.38 kg of a fine
gray powder (i.e., Co) was recovered.
Example 24
[0132] Example 22 was repeated except the temperature in all three
zones of the VTR was increased to 800.degree. C. Approximately 0.36
kg of a fine gray powder (i.e., Co) was recovered.
Example 25
[0133] Example 22 was repeated except Co.sub.3O.sub.4 was the feed
material. The new feed material had a surface area of 1.5 m.sup.2/g
and had an average agglomerate size of 4 microns. The material was
obtained from OMG Kokkola Chemicals Oy (Kokkola, Finland) and had a
lot number of C12-9313-1. This feed material was also black in
color. The feed rate was set at 1.07 kg per hour. Approximately
0.36 kg of dry product was collected in 30 minutes. The product was
a fine gray powder (i.e., Co powder).
Example 26
[0134] Example 25 was repeated except the counter-current hydrogen
gas flow rate was increased to 100 scfh. Approximately 0.38 kg of a
fine, dry, gray powder (i.e., Co powder) was collected.
Example 27
[0135] Example 25 was repeated except the temperature on all three
zones of the VTR was increased to 800.degree. C. Approximately 0.40
kg of a fine, dry, gray powder (i.e., Co powder) was collected.
[0136] The results of Examples 21 to 27 indicate that the
Co.sub.3O.sub.4 can be effectively reduced to cobalt powder by the
present invention. Further, by using this invention the surface
area differences in the feed materials can be maintained in the
final cobalt powder. The materials produced with the higher surface
area oxide were much more pyrophoric (suggesting higher surface
area) than the products made with the lower surface area oxide.
[0137] A summary of the run conditions for the Reduction of Cobalt
Oxide, Examples 21-27, is given below in Table 10.
10TABLE 10 Feed Rate Gas Gas Flow Temp. Example Feed (kg/hr) Phase
Rate (scfh) Mode (.degree. C.) 21 Co.sub.3O.sub.4 (0.9 SA) 1.43
Hydrogen 50 Counter-current 400 22 Co.sub.3O.sub.4 (0.9 SA) 1.43
Hydrogen 50 Counter-current 600 23 Co.sub.3O.sub.4 (0.9 SA) 1.43
Hydrogen 100 Counter-current 600 24 Co.sub.3O.sub.4 (0.9 SA) 1.43
Hydrogen 50 Counter-current 800 25 Co.sub.3O.sub.4 (1.5 SA) 1.07
Hydrogen 50 Counter-current 600 26 Co.sub.3O.sub.4 (1.5 SA) 1.07
Hydrogen 100 Counter-current 600 27 Co.sub.3O.sub.4 (1.5 SA) 1.07
Hydrogen 50 Counter-current 800
[0138] A summary of the experimental results for the Reduction of
Cobalt Oxide, Examples 21-27, is given below in Table 11.
11TABLE 11 Run Time Product Collected Product Product Example
(min.) (kg) Color Composition 21 20 0.43 Black Co.sub.3O.sub.4 22
20 0.40 Gray-Black Co/Co.sub.3O.sub.4 23 20 0.38 Gray Co 24 20 0.36
Gray Co 25 30 0.36 Gray Co 26 30 0.38 Gray Co 27 30 0.40 Gray
Co
[0139] A summary of analyses on the cobalt products collected from
Examples 21-27 is given below in Table 12.
12TABLE 12 Surface Conversion Area Oxygen Carbon Sulfur Example Co
[%] [%] (m.sup.2/g) [%] [ppm] [ppm] 21 73.5 1 1.2 -- -- -- 22 -- --
5.1 -- -- -- 23 -- -- 5.2 -- -- -- 24 -- -- 3.1 -- -- -- 25 -- --
5.6 2.9 723 <10 26 -- -- 5.8 -- -- -- 27 -- -- 2.2 2.2 459
12
[0140] Oxidation of Cobalt Monoxide
Example 28
[0141] The reactor described above was used to carry out the
general reaction shown below.
3CoO+AirCo.sub.3O.sub.4 (Reaction 7)
[0142] The CoO powder feed material was obtained from OMG Kokkola
Chemicals Oy (Kokkola, Finland). This particular material had an
average agglomerate size of 1-2 microns. The powder was brownish in
color and the lot number was D13-0023. The feed material was fed
into the vertical transport reactor at a rate of 2.98 kg per hour.
The gas medium used was air flowing at 35 scfh in a counter-current
mode. The temperatures for all three zones of the VTR were
controlled at 600.degree. C. Under these conditions the residence
time was estimated to be 2-4 seconds. After 45 minutes had elapsed
the feeder was shut off and the product was removed from the
collection can. Approximately 2.4 kg of fine black powder (i.e.,
Co.sub.3O.sub.4) was recovered.
Example 29
[0143] Example 28 was repeated except the temperature in all three
zones of the VTR was increased to 700.degree. C. After 30 minutes,
approximately 1.56 kg of a fine black powder (i.e.,
Co.sub.3O.sub.4) was recovered.
Example 30
[0144] Example 28 was except the temperature in all three zones of
the VTR was increased to 800.degree. C. After 30 minutes,
approximately 1.6 kg of a fine black powder (i.e., Co.sub.3O.sub.4)
was recovered.
[0145] A summary of analyses on the Co.sub.3O.sub.4 products
collected from Examples 28-30 is given below in Table 13.
13TABLE 13 Surface Crystallite Crystallite Metallic Area AD TD Size
Size Example Co [%] CoO [%] Co [%] (m.sup.2/g) (g/cc) (g/cc) [220]
in nm [311] in nm 28 -- -- <1 3.6 0.75 1.11 20 15 29 -- -- <1
3.4 0.81 1.12 30 25 30 -- -- <1 3.3 0.80 1.10 40 39
[0146] Decomposition/Reduction of Cobalt Oxalate
Example 31
[0147] The reactor described above was used to simultaneously
decompose and reduce cobalt oxalate (CoC.sub.2O.sub.4*2H.sub.2O) to
Cobalt Powder. The cobalt oxalate feed material used was an
experimental material obtained from OMG Kokkola Chemicals Oy
(Kokkola, Finland). The oxalate powder has an average agglomerate
size of approximately 40 microns and is pink-orange in color. The
feed material was fed into the vertical transport reactor at a rate
of 0.30 kg per hour. The gas medium used was hydrogen flowing at 50
scfh in a counter-current mode. The temperatures for all three
zones of the VTR were controlled at 500.degree. C. Under these
conditions the residence time was estimated to be 2-4 seconds.
After 30 minutes had elapsed the feeder was shut off and the
product was removed from the collection can. Approximately 0.1 kg
of fine gray-black powder (i.e., Co & Co.sub.3O.sub.4) was
recovered.
Example 32
[0148] Example 31 was repeated except the temperature in all three
zones of the VTR was increased to 600.degree. C. After 30 minutes
had elapsed the feeder was shut off and the product was removed
from the collection can. Approximately 0.1 kg of fine gray powder
(i.e., Co) was recovered.
Example 33
[0149] Example 31 was repeated except the temperature in all three
zones of the VTR was increased to 800.degree. C. After 30 minutes
had elapsed the feeder was shut off and the product was removed
from the collection can. Approximately 0.1 kg of fine gray powder
(i.e., Co) was recovered.
[0150] A summary of analyses on the cobalt products collected from
Examples 31-33 is given below in Table 14.
14TABLE 14 Surface Conversion Area Oxygen Carbon Sulfur Example Co
[%] [%] (m.sup.2/g) [%] [ppm] [ppm] 31 -- -- 17.0 -- -- -- 32 -- --
3.2 1.0 670 <10 33 -- -- 1.1 1.1 313 <10
[0151] Decomposition/Oxidation of Cobalt Oxalate
Example 34
[0152] The reactor described above was used to simultaneously
decompose and oxidize cobalt oxalate (CoC.sub.2O.sub.4*2H.sub.2O)
to Cobalt Oxide Powder. The cobalt oxalate feed material used was
an experimental material obtained from OMG Kokkola Chemicals Oy
(Kokkola, Finland). The oxalate powder has an average agglomerate
size of approximately 40 microns and is pink-orange in color. The
feed material was fed into the vertical transport reactor at a rate
of 0.30 kg per hour. The gas medium used was air flowing at 50 scfh
in a counter-current mode. The temperatures for all three zones of
the VTR were controlled at 600.degree. C. Under these conditions
the residence time is estimated to be 2-4 seconds. After 30 minutes
had elapsed the feeder was shut off and the product was removed
from the collection can. Approximately 0.15 kg of fine black powder
(i.e., Co.sub.3O.sub.4) was recovered.
Example 35
[0153] Example 34 was repeated except the temperature in all three
zones of the VTR was increased to 800.degree. C. After 30 minutes
had elapsed the feeder was shut off and the product was removed
from the collection can. Approximately 0.15 kg of fine black powder
(i.e., Co.sub.3O.sub.4) was recovered.
[0154] A summary of analyses on the Co.sub.3O.sub.4 products
collected from Examples 34 and 35 is given below in Table 15.
15TABLE 15 Surface Crystallite Crystallite Metallic Area AD TD Size
Size Example Co [%] CoO [%] Co [%] (m.sup.2/g) (g/cc) (g/cc) [220]
in nm [311] in nm 34 -- -- <1 2.4 0.37 0.81 -- -- 35 -- -- <1
1.4 0.29 0.59 -- --
[0155] Calcination/Decomposition of LiCoO.sub.2 Feed
Example 36
[0156] The reactor described above was used in the production of
LiCoO.sub.2. An experimental LiCoO.sub.2 feed material consisting
of a mixture of LiCO.sub.3 and Co.sub.3O.sub.4 was used. The
reactor was used in counter-current mode at an airflow rate of 50
scfh. The feed material was gray in color and was fed at a rate of
0.4 kg per hour. The temperatures of all three zones of the VTR
were set at 800.degree. C. After 20 minutes, approximately 0.10 kg
of a fine black powder was collected. The material clearly changed
color during the reaction.
Example 37
[0157] Example 36 was repeated except the temperature in all three
zones of the VTR was increased to 1000.degree. C. After 20 minutes,
approximately 0.10 kg of a fine black powder was collected.
[0158] The following examples 38-82 all were conducted in a
vertical transport reactor similar to the VTR used in examples
1-37, and depicted in FIG. 1, except that a gaseous dispersion
nozzle was used to disperse the feed powder instead of a mechanical
disperser. The reactor had at its core a furnace with a heated zone
that was 6 inches in diameter and 5 foot long. The reaction tube
was constructed out of a high-temperature, nickel-based alloy, and
extended approximately 3 feet above and 3 feet below the furnace
supplying the heat. The furnace had three independently controlled
heating zones capable of producing a maximum temperature of
1200.degree. C. The feed material was fed via a screw feeder to a
dispersion nozzle at the top of the vertical transport reactor. The
dispersion nozzle had variable inside diameters of 3 mm and 5 mm.
The dispersion gas (air) carried the powdered feed to and through
the furnace hot zone and a cooling zone. The product of the
reaction was collected in a product collection can at the bottom of
the reactor.
[0159] In addition to the dispersion gas which was fed co-current
with the powder feed, a second process gas (also air) was fed
counter-current to the powder feed. In the examples 38-82 given
below, all three reaction zones were at the same temperature.
[0160] The products of Examples 38-82 were analyzed to determine
their content, crystallite size, surface area, and density. Cobalt
content (Co [%]) in cobalt oxide or cobalt, cobalt monoxide content
(CoO [%] in cobalt oxide, cobalt metal content (Metallic Co [%]),
crystallite size (Crystallite size [220] and Crystallite size
[311]), surface area, apparent density (AD), and tap density (TD)
all were measured in the same manner as they were for Examples
1-37.
[0161] Oxygen, carbon, and sulfur contents by weight were measured
by the ASTM E1019 standard using an oxygen analyzer manufactured by
LECO Corporation (St. Josephs, Mich.).
[0162] Some products were also analyzed for particle size using
Fischer Sub-Sieve Size (FSSS) based on the ASTM B330 or C721
standards. The analysis provides the particle size of the product
in microns. Particle size also was measured by a dry laser
scattering method in which powder product was dispersed in an air
stream and passed by a laser beam. The laser beam scatters at
different angles depending on the particle size distribution of the
sample product. The diffraction angles are measured and the
particle size distribution determined. Ten percent of the particles
had a size of less than d10, fifty percent of the particles had a
size less than d50, and ninety percent of the particles had a size
less than d90.
[0163] Decomposition/Oxidation of Cobalt Hydroxide
Example 38
[0164] The above-described reactor was used to carry out the same
reaction as in Examples 1-7:
3Co(OH).sub.2+airCo.sub.3O.sub.4+3H.sub.2O (vapor) (Reaction 1)
[0165] The Co(OH).sub.2 feed material was identical to that used in
Examples 1-7. The Co(OH).sub.2 was fed at 1.2 kg/hour. Both the
dispersion gas and the process gas were air, with the dispersion
gas flowing at 3 m.sup.3/hour and the process gas flowing at 0.5
m.sup.3/hour. The average temperatures for all three zones of the
VTR, the feeder pressure and dispersion pressure were as set forth
in Table 16 below. The inside diameter of the disperser nozzle was
3 mm.
Example 39
[0166] Example 38 was repeated except that the dispersion gas flow
was increased to 5 m.sup.3/hour, and the average temperatures for
all three zones of the VTR, the feeder pressure and dispersion
pressure were as set forth in Table 16 below.
Example 40
[0167] Example 38 was repeated except that the dispersion gas flow
rate was increased to 4 m.sup.3/hour, and the average temperatures
for the three zones of the VTR, the feeder pressure and dispersion
pressure were as set forth in Table 16 below.
Example 41
[0168] Example 38 was repeated except that the dispersion gas flow
rate was 3.9 m.sup.3/hour, the process gas flow rate was 1
m.sup.3/hour, and the average temperatures for the three zones of
the VTR, the feeder pressure and dispersion pressure were as set
forth in Table 16 below.
Example 42
[0169] Example 40 was repeated except that the process gas flow
rate was increased to 1.7 m.sup.3/hour, and the average
temperatures for the three zones of the VTR and the feeder pressure
and dispersion pressure were as set forth in Table 16 below.
Example 43
[0170] Example 42 was repeated except that the process gas flow
rate was reduced to 1 m.sup.3/hour, and the average temperatures
for the three zones of the VTR and the feeder pressure and
dispersion pressure were as set forth in Table 16 below.
Example 44
[0171] Example 43 was repeated except that the Co(OH).sub.2 feed
rate was increased to 3 kg/hour, and the average temperatures for
the three zones of the VTR and the feeder pressure and dispersion
pressure were as set forth in Table 16 below.
Example 45
[0172] Example 43 was repeated except that the Co(OH).sub.2 feed
rate was increased to 5 kg/hour, and the average temperatures for
the three zones of the VTR and the feeder pressure and dispersion
pressure were as set forth in Table 16 below.
Example 46
[0173] Example 43 was repeated except that the Co(OH).sub.2 feed
rate was increased to 10 kg/hour, the dispersion gas flow rate was
decreased to 3 m.sup.3/hour, and the average temperatures for the
three zones of the VTR and the feeder pressure and dispersion
pressure were as set forth in Table 16 below.
Example 47
[0174] Example 46 was repeated except that the dispersion gas feed
rate was increased to 5 m.sup.3/hour, the disperser nozzle's inside
diameter was increased to 5 mm, and the average temperatures for
the three zones of the VTR and the feeder pressure and dispersion
pressure were as set forth in Table 16 below.
Example 48
[0175] Example 47 was repeated except that the Co(OH).sub.2 feed
rate was increased to 12.5 kg/hour, and the average temperatures
for the three zones of the VTR and the feeder pressure and
dispersion pressure were as set forth in Table 16 below.
Example 49
[0176] Example 47 was repeated except that the Co(OH).sub.2 feed
rate was increased to 15 kg/hour, and the average temperatures for
the three zones of the VTR and the feeder pressure and dispersion
pressure were as set forth in Table 16 below.
Example 50
[0177] Example 47 was repeated except that the Co(OH).sub.2 feed
rate was increased to 17.5 kg/hour, and the average temperatures
for the three zones of the VTR and the feeder pressure and
dispersion pressure were as set forth in Table 16 below.
Example 51
[0178] Example 47 was repeated except that the Co(OH).sub.2 feed
rate was increased to 20 kg/hour, and the average temperatures for
the three zones of the VTR and the feeder pressure and dispersion
pressure were as set forth in Table 16 below.
Example 52
[0179] Example 47 was repeated except that the Co(OH).sub.2 feed
rate was increased to 21.05 kg/hour, and the average temperatures
for the three zones of the VTR and the feeder pressure and
dispersion pressure were as set forth in Table 16 below.
[0180] A summary of the run conditions for Examples 38-52 is given
below in Table 16.
16TABLE 16 Feed Disperse Process Temp Feeder Disp. Rate Gas Gas
Temp 1 Temp 2 Temp 3 product Pressure Pressure Nozzle Example
(kg/hr) (m.sup.3/h) (m.sup.3/h) [.degree. C.] [.degree. C.]
[.degree. C.] (.degree. C.) (mm H2O) (mm H2O) (mm) 38 1.2 3 0.5 714
711 714 12 651 616 3 39 1.2 5 0.5 704 703 707 13 701 1776 3 40 1.2
4. 0.5 696 697 698 13 701 1302 3 41 1.2 3.9 1 703 701 699 13 701
1251 3 42 1.2 4 1.7 703 702 701 13 701 1307 3 43 1.2 4 1 900 902
899 17 -- 1342 3 44 3 4 1 903 901 903 25 1506 1418 3 45 5 4 1 900
885 903 31 1596 1485 3 46 10 3 1 900 885 888 25 3178 3044 3 47 10 5
1 879 893 902 54 620 510 5 48 12.5 5 1 899 899 897 67 679 522 5 49
15 5 1 905 900 900 70 735 560 5 50 17.5 5 1 904 900 902 77 780 603
5 51 20 5 1 851 862 892 80 879 677 5 52 21.05 5 1 875 878 895 80
894 648 5
[0181] A summary of the experimental results of Examples 38-52 is
given below in Table 17.
17TABLE 17 Example Cobalt % S.A. m.sup.2/g 38 72.4 11.2 39 72.5
12.2 40 72.8 12.6 41 72.6 11.9 42 72.3 12.5 43 72.6 3.9 44 72.9 4.1
45 73.1 3.9 46 73.1 4.7 47 73 5.3 48 73.1 6 49 72.9 4.7 50 73.1 5.8
51 72.7 6.8 52 72.8 6.2
[0182] Additional analyses of the products of Examples 40, 43, 47
and 51 is given below in Table 18.
18TABLE 18 Surface Crystallite Crystallite Co Area Size [220] Size
[311] CoO d10 d50 d90 Example [%] (m.sup.2/g) in nm nm [%] (.mu.)
(.mu.) (.mu.) 40 72.8 12.6 21 19 0 1 8.2 42.9 43 72.6 3.9 63 69 0.4
0.9 16.8 49.1 47 73 5.3 70 65 0.6 1 14.5 46.6 51 72.7 6.8 49 48 0.4
0.9 8.8 45.2
[0183] As Examples 38-52 demonstrate, a high quality cobalt oxide
powder, with nanometer sized crystallites and agglomerates in the
range of 8 to 20 microns, can be produced by the present
invention.
[0184] Production of Nickel from Nickel Hydroxide
Example 53
[0185] The reactor employed in Examples 38-52 was used to carry out
the reaction shown below.
Ni(OH).sub.2+H.sub.2Ni+2H.sub.2O (Reaction 8)
[0186] The Ni(OH).sub.2 feed material was obtained from OMG Kokkola
Chemicals Oy. (Kokkola, Finland),.grade NO1, Lot number 1034. This
particular material had a d50 particle size of approximately 12.5
microns. The feed material was fed into the vertical transport
reactor at a rate of 3 kg/hr. The dispersion gas was nitrogen fed
at a rate of 50 liters per minute, and the process gas was hydrogen
fed at a rate of 1.0 m.sup.3/hr. The dispersion nozzle had a 4 mm
inside diameter. The temperatures at all three zones of the VTR
were controlled at 500.degree. C.
Example 54
[0187] Example 53 was repeated except that the temperatures on all
three zones of the VTR was increased to 600.degree. C.
Example 55
[0188] Example 53 was repeated except that the temperatures on all
three zones of the VTR was increased to 700.degree. C.
Example 56
[0189] Example 53 was repeated except that the temperatures on all
three zones of the VTR was increased to 800.degree. C.
Example 57
[0190] Example 53 was repeated except that the temperatures on all
three zones of the VTR was increased to 900.degree. C.
Example 58
[0191] Example 53 was repeated except that the temperatures on all
three zones of the VTR was increased to 1000.degree. C.
Example 59
[0192] Example 55 was repeated except that the process gas feed
rate was increased to 1.5 m.sup.3/hr.
Example 60
[0193] Example 54 was repeated except that the process gas feed
rate was increased to 1.5 m.sup.3/hr.
Example 61
[0194] Example 53 was repeated except that the process gas feed
rate was increased to 1.5 m.sup.3/hr.
Example 62
[0195] Example 53 was repeated except that the process gas feed
rate was increased to 2.0 m.sup.3/hr.
Example 63
[0196] Example 54 was repeated except that the process gas feed
rate was increased to 2.0 m.sup.3/hr.
Example 64
[0197] Example 55 was repeated except that the process gas feed
rate was increased to 2.0 m.sup.3/hr.
Example 65
[0198] Example 63 was repeated except that the feed material was
fed into the vertical transport reactor at a rate of 10 kg/hr.
Example 66
[0199] Example 63 was repeated except that the feed material was
fed into the vertical transport reactor at a rate of 15 kg/hr.
Example 67
[0200] Example 63 was repeated except that the feed material was
fed into the vertical transport reactor at a rate of 20 kg/hr.
Example 68
[0201] Example 65 was repeated except that the process gas feed
rate was increased to 2.5 m.sup.3/hr. and the dispersion gas was
hydrogen fed at 1000 liters per minute. Example 68 demonstrates the
use of high concentrations of hydrogen and the use of hydrogen as
the dispersing gas produces nickel with a low concentration of
oxygen.
[0202] A summary of the run conditions for Examples 53-68 is given
below in Table
19TABLE 19 Feed Process Disperse Nozzle Temp Rate Gas H.sub.2 Gas
N.sub.2 Size Example Feed (.degree. C.) (kg/hr) (m.sup.3/hr)
(l/min) (mm) 53 Ni(OH).sub.2 500 3 1.0 50 4 54 Ni(OH).sub.2 600 3
1.0 50 4 55 Ni(OH).sub.2 700 3 1.0 50 4 56 Ni(OH).sub.2 800 3 1.0
50 4 57 Ni(OH).sub.2 900 3 1.0 50 4 58 Ni(OH).sub.2 1000 3 1.0 50 4
59 Ni(OH).sub.2 700 3 1.5 50 4 60 Ni(OH).sub.2 600 3 1.5 50 4 61
Ni(OH).sub.2 500 3 1.5 50 4 62 Ni(OH).sub.2 500 3 2.0 50 4 63
Ni(OH).sub.2 600 3 2.0 50 4 64 Ni(OH).sub.2 700 3 2.0 50 4 65
Ni(OH).sub.2 600 10 2.0 50 4 66 Ni(OH).sub.2 600 15 2.0 50 4 67
Ni(OH).sub.2 600 20 2.0 50 4 68 Ni(OH).sub.2 600 10 2.5 1000 with 4
H.sub.2
[0203] A summary of the experimental results of Examples 53-68 is
given below in Table 20.
20TABLE 20 Surface Car- Ex- Area FSSS d50 AD bon Oxygen N S ample
(m.sup.2/g) (.mu.) (.mu.) (g/cc) (%) (%) (%) (ppm) 53 71.40 2.20 --
0.85 0.0 0.90 -- -- 54 -- -- -- -- 0.0 0.80 -- -- 55 -- -- -- --
0.0 2.80 -- 500 56 1.00 6.00 37.7 -- 0.0 0.36 0.44 1700 57 4.50 --
-- -- 0.0 0.50 0.46 1400 58 -- -- -- -- 0.0 0.63 0.50 1100 59 --
4.40 31.9 1.6 0.0 0.35 0.45 2500 60 1.40 2.90 35.4 1.2 0.0 0.79
0.58 2300 61 -- 2.80 40.3 1.0 0.0 1.00 0.53 2000 62 -- -- -- -- 0.0
1.10 -- -- 63 0.40 2.40 34.7 1.1 0.0 40.84 0.55 2200 64 -- 4.60
33.7 1.7 0.0 0.39 0.44 1600 65 -- -- -- -- 0.1 >5 -- -- 66 -- --
-- -- 0.2 >5 -- -- 67 -- -- -- -- 0.1 >5 -- -- 68 -- 2.20
35.2 1.5 0.0 0.95 <0.1 450
[0204] Examples 53-68 demonstrate the applicability of the present
invention to the decomposition and reduction of nickel hydroxide to
produce nickel metal powder, and more generally to the
decomposition and reduction of metal hydroxides to produce fine
metal powders.
[0205] Production of Nickel from Nickel Carbonate
Example 69
[0206] The reactor employed in Examples 38-68 was used to carry out
the reaction shown below.
NiCO.sub.3+H.sub.2Ni+CO.sub.2+H.sub.2O (Reaction 9)
[0207] The NiCO.sub.3 feed material was obtained from OMG Kokkola
Chemicals Oy. (Kokkola, Finland), grade N50 (N53), Lot number 1024.
This particular material had a d50 particle size of approximately
14.0 microns. The feed material was fed into the vertical transport
reactor at a rate of 3 kg/hr. The dispersion gas was nitrogen fed
at a rate of 30 liters per minute, and the process gas was hydrogen
fed at a rate of 1.5 m.sup.3/hr. The dispersion nozzle had a 4 mm
inside diameter. The temperatures at all three zones of the VTR
were controlled at 500.degree. C.
Example 70
[0208] Example 69 was repeated except that the temperatures on all
three zones of the VTR was increased to 600.degree. C.
Example 71
[0209] Example 69 was repeated except that the temperatures on all
three zones of the VTR was increased to 700.degree. C.
Example 72
[0210] Example 69 was repeated except that the temperatures on all
three zones of the VTR was increased to 800.degree. C. and the
process gas feed rate was decreased to 1.0 m.sup.3/hr.
Example 73
[0211] Example 72 was repeated except that the temperatures on all
three zones of the VTR was increased to 900.degree. C.
Example 74
[0212] Example 72 was repeated except that the temperatures on all
three zones of the VTR was increased to 1000.degree. C. and the
dispersion gas feed rate was increased to 30 liters per minute.
Example 75
[0213] Example 69 was repeated except that the process gas feed
rate was increased to 2.0 m.sup.3/hr. and the dispersion gas feed
was increased to 50 liters per minute.
Example 76
[0214] Example 75 was repeated except that the process gas feed
rate was increased to 2.5 m.sup.3/hr.
Example 77
[0215] Example 75 was repeated except that the temperatures on all
three zones of the VTR were increased to 550.degree. C. and the
process gas feed rate was decreased to 1.5 m.sup.3/hr.
Example 78
[0216] Example 77 was repeated except that the process gas feed
rate was increased to 2.0 m.sup.3/hr.
Example 79
[0217] Example 77 was repeated except that the process gas feed
rate was increased to 2.5 m.sup.3/hr. and the inside diameter of
the dispersion nozzle was reduced to 3 mm.
Example 80
[0218] Example 69 was repeated except that the process gas feed
rate was increased to 2.0 m.sup.3/hr. and the inside diameter of
the dispersion nozzle was reduced to 3 mm.
Example 81
[0219] Example 80 was repeated except that the process gas feed
rate was increased to 2.5 m.sup.3/hr.
Example 82
[0220] Example 81 was repeated except that the temperatures on all
three zones of the VTR was increased to 550.degree. C. and the
process gas feed rate was decreased to 1.5 m.sup.3/hr.
Example 83
[0221] Example 82 was repeated except that the process gas feed
rate was increased to 2.0 m.sup.3/hr.
Example 84
[0222] Example 82 was repeated except that the process gas feed
rate was increased to 2.5 m.sup.3/hr.
[0223] A summary of the run conditions for Examples 69-84 is given
below in Table
21TABLE 21 Feed Process Disperse Nozzle Temp Rate Gas H2 Gas N2
Size Example Feed (.degree. C.) (kg/hr) (m.sup.3/hr) (l/min) (mm)
69 NiCO.sub.3 500 3 1.5 30 4 70 NiCO.sub.3 600 3 1.5 30 4 71
NiCO.sub.3 700 3 1.5 30 4 72 NiCO.sub.3 800 3 1.0 30 4 73
NiCO.sub.3 900 3 1.0 30 4 74 NiCO.sub.3 1000 3 1.0 30 4 75
NiCO.sub.3 500 3 2.0 50 4 76 NiCO.sub.3 500 3 2.5 50 4 77
NiCO.sub.3 550 3 1.5 50 4 78 NiCO.sub.3 550 3 2.0 50 4 79
NiCO.sub.3 550 3 2.5 50 3 80 NiCO.sub.3 500 3 2.0 30 3 81
NiCO.sub.3 500 3 2.5 30 3 82 NiCO.sub.3 550 3 1.5 30 3 83
NiCO.sub.3 550 3 2.0 30 3 84 NiCO.sub.3 550 3 2.5 30 3
[0224] A summary of the experimental results of Examples 69-84 is
given below in Table 22.
22TABLE 22 Surface Car- Ex- Area FSSS d50 AD bon Oxygen N S ample
(m.sup.2/g) (.mu.) (.mu.) (g/cc) (%) (%) (%) (ppm) 69 7.50 2.20
20.6 0.8 0.1 1.20 0.35 340 70 1.70 3.50 17.3 1.2 0.0 0.32 0.30 370
71 1.40 2.40 18.9 1.2 0.0 0.26 0.39 270 72 1.00 4.20 26.3 1.1 0.0
0.40 0.32 380 73 0.80 4.80 41.6 0.9 0.0 0.66 0.29 360 74 0.50 -- --
-- 0.0 1.40 0.27 260 75 -- -- -- 0.95 0.1 0.77 1.40 380 76 -- -- --
-- -- 3.90 1.90 -- 77 -- -- -- -- -- 2.20 2.50 -- 78 6.50 3.00 --
0.95 0.1 0.36 0.56 320 79 4.30 3.10 -- 0.95 0.1 0.61 1.00 440 80
1.50 -- -- -- 0.1 1.60 0.68 130 81 -- -- -- -- -- 3.60 -- -- 82 3.8
3 18.5 0.81 0.0 0.59 -- 120 83 1.6 3 18.5 0.83 0.0 0.81 -- 80 84 --
3.3 18.6 0.78 0.1 1.80 -- --
[0225] Examples 69-84 demonstrate the applicability of the present
invention to the decomposition and reduction of nickel carbonate to
produce nickel metal powder, and more generally to the
decomposition and reduction of metal carbonates to produce fine
metal powders.
[0226] Examples 69-84 also demonstrate that the surface area can be
controlled by controlling the reaction temperature. For example,
scanning electron microscopy (SEM) photomicrographs of the product
of Example 69 showed overall agglomerates approximately 15 to 20
microns in diameter. The agglomerates were composed of crystallites
that were less than 100 nm in diameter. SEM photomicrographs of the
product of Example 74 showed overall agglomerates approximately 30
microns in diameter. The crystallites that made up the agglomerates
were approximately 1 to 1.5 microns in diameter.
[0227] The following examples 85-87 all were conducted using a
Thermal Technology Model 1000-45180-FP60 Astro.TM. vertical
graphite-tube reactor available from Thermal Technology, Inc.
(Santa Rosa, Calif.). The furnace tube was 91.44 cm in length with
a 45.72 cm hot zone in the center. The inner diameter was 8.89 cm.
A particle feeder connected at its outlet into a 0.3175 cm inside
diameter stainless steel tube which in turn connected to a
water-cooled, copper lance in the top of the reactor that ended at
the top of the reactor hot zone. To prevent any dead space, the gap
between the water-cooled lance and the inner graphite tube was
plugged with a piece of graphite. The graphite plug ended at the
lance end at the top of the hot zone. A purge stream of diluent
nitrogen gas entered the tube reactor between the lance and the
graphite plug.
[0228] Particulate feed material was entrained in argon gas at the
outlet of the particle feeder and the dispersion flowed to the hot
zone of the reactor furnace tube. After exiting the hot zone of the
reactor, the gaseous dispersion flowed into a cooling zone
consisting of a water-cooled aluminum tube that was 29.85 cm long
and had an inner diameter of 16.51 cm. This expanded section slowed
the velocity of the particles and cooled them. Particles were
collected in a stainless steel vessel at the outlet of the cooling
zone. The stainless steel vessel was purged with an additional 3.00
liters per minute of N.sub.2 to continue cooling and prevent
further reaction. The effluent gas from the vessel flowed through a
filter to collect any residual powder retained in the gas.
[0229] The operation of this rapid heating reactor was similar to
that described in U.S. Pat. No. 5,110,565, previously incorporated
herein by reference.
[0230] The products of Examples 85-87 were analyzed to determine
their composition and surface area. Nickel metal contents were
measured by X-ray diffraction. Oxygen contents were measured by the
ASTM E1019 standard using an oxygen analyzer manufactured by LECO
Corporation (St. Josephs, Mich.). Surface area was measured by BET
based on nitrogen absorption on the surface following the ASTM
D4567 standard.
[0231] Nickel Metal Powder from Nickel Oxalate
Example 85
[0232] 20.24 grams of nickel oxalate dihydrate
(NiC.sub.2O.sub.4.2H.sub.2O- ) (obtained from All-Chemie, Mt.
Peasant, S.C.) were dehydrated by heating it to 200.degree.
C..+-.10.degree. C. and holding it for 6 hours in a tube furnace
under flowing N.sub.2. This heat treatment removed 3.36 grams of
water thus reducing the amount of water later entering the hot
graphite reactor. This partially dehydrated powder was stored in a
standard vacuum desiccator until used.
[0233] The particle feeder to the vertical graphite tube reaction
furnace was filled with 6.9 grams of the partially dehydrated
nickel oxalate dihydrate. The powder was entrained at the outlet
from the feeder in an argon gas stream flowing at 3.76 liters per
minute. A purge stream of diluent nitrogen gas entered the tube
reactor between the lance and the graphite plug. The entrained
particles flowed at a rate of 0.75 grams per minute into the hot
zone of the reactor furnace that had been heated to a temperature
of 1000.degree. C. The particles had a residence time of 3.6
seconds.
[0234] The powders collected were analyzed for composition by X-ray
diffraction and the LECO oxygen analyzer. The X-ray diffraction
confirmed that the only crystalline species present is nickel metal
and that the product is fine nickel metal powder. The BET
measurement showed the nickel powder has a surface area of 14
m.sup.2/g.
[0235] This example indicates that nickel oxalate dihydrate
(NiC.sub.2O.sub.4.2H.sub.2O) can be decomposed in seconds to
produce ultra-fine nickel metal powder by the present
invention.
Example 86
[0236] Example 85 was repeated, except that 8.9 grams of the same
partially dehydrated nickel oxalate dihydrate of Example 85 was
reacted to nickel metal, the entraining argon gas flow was 4.35
liters per minute, the diluent nitrogen gas purge flow was 3.00
l/min., the furnace temperature was 500.degree. C., and the
particle residence time was 5.5 seconds. The product collected was
analyzed. X-ray diffraction showed that the only crystalline
product is nickel metal. The BET measurement indicated that the
nickel powder has a surface area of 8.6 m.sup.2/g.
Example 87
[0237] Example 85 was repeated, except that 8.9 grams of nickel
oxalate dihydrate--partially dehydrated the same as in Example
85--was reacted to nickel metal, the entraining argon gas flow was
4.35 liters per minute, the diluent nitrogen gas purge flow was
1.50 liters per minute, the furnace temperature was 750.degree. C.,
and the particle residence time was 5.5 seconds.
[0238] The product was collected and analyzed by X-ray diffraction
and BET. The X-ray diffraction showed that the only crystalline
product is nickel metal. The BET measurement indicated that the
nickel powder has a surface area of 2.1 m.sup.2/g.
[0239] The following examples 88-103 all were conducted using a
Theta Gravitronic VII thermogravimetric analyzer (TGA) available
from Theta Corporation (Port Washington, N.Y.). The TGA consisted
of a high temperature graphite furnace with a hot zone of 10.5 cm
in length and an inner diameter of 4.06 cm., a Cahn D-1000
microbalance, and gas flow and temperature control equipment. A
cylindrical, alumina crucible with an inner diameter of 1.6 cm and
a height of 2.54 cm was suspended from the balance into the hot
zone of the furnace using a platinum wire.
[0240] The products of Examples 88-103 were analyzed to determine
their composition and surface area. Nickel metal contents, oxygen
contents, carbon contents, and surface area were measured by the
same methods of Examples 85-87. Some products were analyzed for
particle size by taking images by transmission electron microscopy
(TEM).
[0241] Nickel Metal from Nickel Oxalate
Example 88
[0242] 1.54 g nickel oxalate dihydrate (same as Example 85, but not
partially dehydrated) were placed in the alumina crucible of the
TGA. The furnace was sealed to ambient gases and purged of air. An
argon flow rate of 0.5 liters per minute was maintained throughout
this experiment to remove the CO.sub.2 produced in the reaction.
The furnace was heated at 5.degree. C./min up to 400.degree. C.,
then cooled to 15.degree. C. at 30.degree. C./min. The sample was
held at room temperature under argon flow for at least 2 hours to
fully cool. A 68 percent mass loss was recorded by the TGA. This
mass loss corresponds theoretically to complete conversion of
nickel oxalate dihydrate to nickel metal. The sample was removed
and analyzed by X-ray diffraction and BET. The X-ray diffraction
showed that the only crystalline substance is nickel metal. The BET
surface area was 13 m.sup.2/g.
[0243] This example indicates that nickel metal can be synthesized
from the decomposition of nickel oxalate dihydrate at 400.degree.
C. by the present invention.
Example 89
[0244] Example 88 was repeated except that 2.194 grams of nickel
oxalate dihydrate was reacted to nickel metal. An argon flow rate
of 0.5 liters per minute was maintained throughout the experiment.
The furnace was heated at 10.degree. C./min up to 500.degree. C.,
then cooled to 15.degree. C. at 30.degree. C./min. A 68 percent
mass loss was recorded by the TGA. This corresponds to complete
conversion to nickel metal. The sample was removed and analyzed.
The X-ray diffraction showed that the only crystalline substance is
nickel metal. LECO measurements showed a 0.19 wt % carbon and 1.73
wt % oxygen content. The TEM images indicated that the particles
average 200 nm diameter and are comprised of 10 nm primary
particles.
[0245] This example demonstrates that nano-sized nickel primary
particles can be synthesized from the decomposition of nickel
oxalate dihydrate by the present invention and that these particles
have a residual oxygen content of less than 1.8 wt %.
[0246] Cobalt Metal from Cobalt Oxalate
Example 90
[0247] Example 88 was repeated except that 2.2657 grams of cobalt
oxalate was reacted to form cobalt metal in a 0.8 liter per minute
stream of 10% H.sub.2 in an argon atmosphere. The furnace was
heated at 30.degree. C./min to a temperature of 750.degree. C. A 68
percent mass loss was recorded by the TGA. This corresponds to
complete conversion to cobalt metal. X-ray diffraction showed that
the only crystalline species present is cobalt metal.
[0248] Tin Metal from Tin Oxalate
Example 91
[0249] Example 88 was repeated except that 0.796 grams of tin
oxalate was reacted to form tin metal in a stream of 10% H.sub.2 in
an argon atmosphere. The furnace was heated at 30.degree. C./min to
a temperature of 375.degree. C. A 42 percent mass loss was recorded
by the TGA balance. This corresponds to complete conversion of the
oxalate to the base metal. BET indicated that the surface area is
10 m.sup.2/g (10 nm). X-ray diffraction showed that the only
crystalline species present is tin metal.
[0250] Lead Metal form Lead Oxalate
Example 92
[0251] Example 88 was repeated except that 1.6131 grams of lead
oxalate was reacted to form lead metal in a stream of 0.5 liters
per minute of argon. The furnace was heated at 30.degree. C./min to
a temperature of 375.degree. C. The TGA balance recorded a 27
percent mass loss. This corresponds to complete conversion of the
oxalate to the base metal. X-ray diffraction showed that the only
crystalline species present is lead metal.
[0252] Nickel Metal from Nickel Carbonate
Example 93
[0253] Example 88 was repeated except that 1.3054 grams of nickel
carbonate was reacted to form nickel metal in a 1.3 liter per
minute stream of 10% hydrogen in argon. The furnace was heated at
30.degree. C./min to a temperature of 275.degree. C. A 51 percent
mass loss was recorded by the TGA balance. This corresponds to
complete conversion of the carbonate to the base metal. BET
indicated that the surface area is 2.4 m.sup.2/g. X-ray diffraction
showed that the only crystalline species present is nickel
metal.
[0254] Cobalt Metal from Cobalt Carbonate
Example 94
[0255] Example 88 was repeated except that 1.6427 grams of cobalt
carbonate was reacted to form cobalt metal in a 0.8 liter per
minute stream of 10% hydrogen in argon. The furnace was heated at
30.degree. C./min to a temperature of 900.degree. C. A 50 percent
mass loss was recorded by the TGA balance. This corresponds to
complete conversion of the carbonate to the base metal. BET
indicated that the surface area is 1.2 m.sup.2/g. X-ray diffraction
showed that the only crystalline species present is cobalt
metal.
[0256] Nickel Metal from Nickel Hydroxide
Example 95
[0257] Example 88 was repeated except that 1.5414 grams of nickel
hydroxide was reacted to form nickel metal in a 0.8 liter per
minute stream of 10% hydrogen in argon. The furnace was heated at
30.degree. C./min to a temperature of 900.degree. C. A 40 percent
mass loss was recorded by the TGA balance. This corresponds to
complete conversion of the hydroxide to the base metal. X-ray
diffraction showed that the only crystalline species present is
nickel metal.
[0258] Cobalt Metal from Cobalt Hydroxide
Example 96
[0259] Example 88 was repeated except that 1.2908 grams of cobalt
hydroxide was reacted to form cobalt metal in a 1.3 liter per
minute stream of 5% hydrogen in argon atmosphere. The furnace was
heated at 30.degree. C./min to a temperature of 575.degree. C. A 39
percent mass loss was recorded by the TGA balance. This corresponds
to complete conversion of the hydroxide to the base metal. X-ray
diffraction showed that the only crystalline species present is
cobalt metal.
[0260] Cobalt Metal from Cobalt Acetate Tetrahydrate
Example 97
[0261] Example 88 was repeated except that 1.973 grams of cobalt
acetate tetrahydrate was reacted to form cobalt metal in a 2.3
liter per minute stream of 2% hydrogen in argon atmosphere. The
furnace was heated at 30.degree. C./min to a temperature of
400.degree. C. A 74 percent mass loss was recorded by the TGA
balance. This corresponds to complete conversion of the acetate to
cobalt metal. BET indicated that the surface area is 14 m.sup.2/g.
X-ray diffraction showed that the only crystalline species present
is cobalt metal.
[0262] Cerium Oxide (Ce.sub.7O.sub.12) from Cerium Oxalate
Example 98
[0263] Example 88 was repeated except that 2.2847 grams of cerium
oxalate nonahydrate (9 H.sub.2O) was reacted to form cerium oxide
in a 0.8 liter per minute stream of 10% hydrogen in argon. The
furnace was heated at 30.degree. C./min to a temperature of
800.degree. C. A 51 percent mass loss was recorded by the TGA
balance. This corresponds to complete conversion of the oxalate
nonahydrate into the oxide. X-ray diffraction showed that the only
crystalline species is cerium oxide. BET indicated that the surface
area is 7.6 m.sup.2/g.
[0264] Cerium Oxide (CeO.sub.2) from Cerium Carbonate
Example 99
[0265] Example 88 was repeated except that 2.1834 grams of cerium
carbonate pentahydrate (5 H.sub.2O) was reacted to form cerium
oxide in a 0.8 liter per minute stream of argon. The furnace was
heated at 30.degree. C./min to a temperature of 800.degree. C. A 38
percent mass loss was recorded by the TGA balance. This corresponds
to complete conversion of the oxalate pentahydrate into the oxide.
X-ray diffraction showed that the only crystalline species is
cerium oxide.
[0266] Cerium Oxide (CeO.sub.2) from Cerium Hydroxide
Example 100
[0267] Example 88 was repeated except that 2.4407 grams of cerium
hydroxide was reacted to form cerium oxide in a 0.8 liter per
minute stream of argon. The furnace was heated at 30.degree. C./min
to a temperature of 800.degree. C. A 6 percent mass loss was
recorded by the TGA balance. This corresponds to 33% conversion of
the oxalate into the oxide. X-ray diffraction showed that the only
crystalline species is cerium oxide.
[0268] Lanthanum Oxide (La.sub.2O.sub.3) from Lanthanum Oxalate
Example 101
[0269] Example 88 was repeated except that 1.8693 grams of
lanthanum oxalate hydrate was reacted to form lanthanum oxide in a
0.8 liter per minute stream of 10% hydrogen in argon. The furnace
was heated at 30.degree. C./min. to a temperature of 800.degree. C.
A 50 percent mass loss was recorded by the TGA balance. This
corresponds to complete conversion of the oxalate hexahydrate into
the oxide. X-ray diffraction showed that the only crystalline
species is lanthanum oxide. BET indicated that the surface area is
2.2 m.sup.2/g.
[0270] Neodymium Oxide (Nd.sub.2O.sub.3)from Neodymium Oxalate
(Nd.sub.2(C.sub.2O.sub.4).sub.3.16H.sub.2O)
Example 102
[0271] Example 88 was repeated except that 1.4360 grams of
neodymium oxalate hydrate was reacted to form neodymium oxide in a
0.8 liter per minute stream of argon. The furnace was heated at
30.degree. C./min to a temperature of 800.degree. C. A 60 percent
mass loss was recorded by the TGA balance. This corresponds to
complete conversion of the oxalate into the oxide. X-ray
diffraction showed that the only crystalline species is neodymium
oxide. BET indicated that the surface area is 2.5 m.sup.2/g.
[0272] Neodymium Oxide (Nd.sub.2O.sub.3) from Neodymium Carbonate
(Nd.sub.2(CO.sub.3).sub.3.9H.sub.2O)
Example 103
[0273] Example 88 was repeated except that 2.1834 grams of
neodymium carbonate hydrate was reacted to form neodymium oxide in
a 0.8 liter per minute stream of 10% hydrogen in argon. The furnace
was heated at 30.degree. C./min to a temperature of 800.degree. C.
A 46 percent mass loss was recorded by the TGA balance. This mass
loss corresponds to complete conversion of the oxalate into the
oxide. X-ray diffraction showed that the only crystalline species
is neodymium oxide.
* * * * *