U.S. patent application number 12/082110 was filed with the patent office on 2008-08-07 for titanium and titanium alloys.
This patent application is currently assigned to International titanium Powder, LLC. Invention is credited to Richard P. Anderson, Donn Reynolds Armstrong, Stanley R. Borys.
Application Number | 20080187455 12/082110 |
Document ID | / |
Family ID | 39811918 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080187455 |
Kind Code |
A1 |
Armstrong; Donn Reynolds ;
et al. |
August 7, 2008 |
Titanium and titanium alloys
Abstract
A titanium powder or alloy powder produced by introducing a
TiCl.sub.4 vapor into a continuum or flowing stream of sodium metal
at a velocity not less than sonic velocity of the vapor wherein the
sodium is present in an amount greater than stoichiometric
sufficient to maintain substantially all the reaction products
below the sintering temperature thereof and wherein said Ti powder
has a packing fraction in the range of from about 4% to about 11%.
The powders without fines have a particle diameter in the range of
from about 3.3 to about 1.3 microns based on a calculated size of a
sphere from a BET surface area in the range of from about 0.4 to
about 1.0 m.sup.2/g.
Inventors: |
Armstrong; Donn Reynolds;
(Waukesha, WI) ; Borys; Stanley R.; (Elmhurst,
IL) ; Anderson; Richard P.; (Clarendon Hills,
IL) |
Correspondence
Address: |
Harry M. Levy;Olson & Cepuritis, Ltd.
36th Floor, 20 North Wacker Drive
Chicago
IL
60606
US
|
Assignee: |
International titanium Powder,
LLC
Woodridge
IL
|
Family ID: |
39811918 |
Appl. No.: |
12/082110 |
Filed: |
April 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10125942 |
Apr 19, 2002 |
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12082110 |
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08691423 |
Aug 2, 1996 |
5779761 |
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10125942 |
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09264577 |
Mar 8, 1999 |
6409797 |
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08691423 |
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08782816 |
Jan 13, 1997 |
5958106 |
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09264577 |
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08691423 |
Aug 2, 1996 |
5779761 |
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08782816 |
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Current U.S.
Class: |
420/417 |
Current CPC
Class: |
B22F 9/28 20130101; C22B
34/1272 20130101; C22B 34/1222 20130101; Y02P 10/20 20151101; C22B
34/00 20130101; C22B 5/04 20130101 |
Class at
Publication: |
420/417 |
International
Class: |
C22C 14/00 20060101
C22C014/00 |
Claims
1-48. (canceled)
49. A titanium powder produced by introducing a TiCl.sub.4 vapor
into a flowing stream of sodium alkali metal at a velocity not less
than sonic velocity of the vapor wherein the sodium is present in
an amount greater than stoichiometric sufficient to maintain
substantially all the reaction products below the sintering
temperature thereof and, wherein said Ti powder has a packing
fraction in the range of from about 4% to about 11%.
50-83. (canceled)
84. A titanium or titanium alloy powder produced by the method of
submerging a titanium halide vapor or mixture of halide vapors in a
continuum of liquid sodium metal thereof present in sufficient
quantities to maintain the titanium or titanium alloy below the
sintering temperatures thereof wherein the powder is titanium
without fines and has a particle diameter in the range of from
about 3.3 to about 1.3 microns based on a calculated size of a
sphere from a BET surface area in the range of from about 0.4 to
about 1.0 m.sup.2/g, and, wherein said Ti powder has a packing
fraction in the range of from about 4% to about 11%.
95-99. (canceled)
Description
RELATED APPLICATIONS
[0001] This application is a continuation of Ser. No. 08/691,423
filed Aug. 2, 1995, now U.S. Pat. No. 5,797,761 and this
application is a continuation of the file wrapper continuation
application of our previously filed co-pending application Ser. No.
09/264,577 filed Mar. 8, 1999, now U.S. Pat. No. 6,409,979 issued
Jul. 25, 2002, which was a continuation-in-part of Ser. No.
08/782,816, filed Jan. 13, 1997, now U.S. Pat. No. 5,958,106 issued
Sep. 28, 1999, which was a continuation-in-part of Ser. No.
08/691,423, filed Aug. 2, 1995, now U.S. Pat. No. 5,779,761 issued
Jul. 14, 1998. The disclosures of each of U.S. Pat. Nos. 5,779,761
and 5,958,106 are incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] This invention relates to the production of elemental
material from the halides thereof and has particular applicability
to those metals and non-metals for which the reduction of the
halide to the element is exothermic. Particular interest exists for
titanium and the present invention will be described with
particular reference to titanium, but is applicable to other metals
and non-metals such as Al, As, Sb, Sn, Be, B, Ta, Ge, V, Nb, Mo,
Ga, Ir, Os, U and Re, all of which produce significant heat upon
reduction from the halide to the metal. For the purposes of this
application, elemental materials include those metals and
non-metals listed above or in Table 1.
[0003] At present titanium production is by reduction of titanium
tetrachloride, which is made by chlorinating relatively high-grade
titanium dioxide ore. Ores containing rutile can be physically
concentrated to produce a satisfactory chlorination feed material;
other sources of titanium dioxide, such as ilmenite, titaniferous
iron ores and most other titanium source materials, require
chemical beneficiation.
[0004] The reduction of titanium tetrachloride to metal has been
attempted using a number of reducing agents including hydrogen,
carbon, sodium, calcium, aluminum and magnesium. Both the magnesium
and sodium reduction of titanium tetrachloride have proved to be
commercial methods for producing titanium metal. However, current
commercial methods use batch processing which requires significant
material handling with resulting opportunities for contamination
and gives quality variation from batch to batch. The greatest
potential for decreasing production cost is the development of a
continuous reduction process with attendant reduction in material
handling. There is a strong demand for both the development of a
process that enables continuous economical production of titanium
metal and for the production of metal powder suitable for use
without additional processing for application to powder metallurgy
or for vacuum-arc melting to ingot form.
[0005] The Kroll process and the Hunter process are the two present
day methods of producing titanium commercially. In the Kroll
process, titanium tetrachloride is chemically reduced by magnesium
at about 1000.degree. C. The process is conducted in a batch
fashion in a metal retort with an inert atmosphere, either helium
or argon. Magnesium is charged into the vessel and heated to
prepare a molten magnesium bath. Liquid titanium tetrachloride at
room temperature is dispersed dropwise above the molten magnesium
bath. The liquid titanium tetrachloride vaporizes in the gaseous
zone above the molten magnesium bath. A reaction occurs on the
molten magnesium surface to form titanium and magnesium chloride.
The Hunter process is similar to the Kroll process, but uses sodium
instead of magnesium to reduce the titanium tetrachloride to
titanium metal and produces sodium chloride as a by product.
[0006] For both processes, the reaction is uncontrolled and
sporadic and promotes the growth of dendritic titanium metal. The
titanium fuses into a mass that encapsulates some of the molten
magnesium (or sodium) chloride. This fused mass is called titanium
sponge. After cooling of the metal retort, the solidified titanium
sponge metal is broken up, crushed, purified and then dried in a
stream of hot nitrogen. Metal ingots are made by compacting the
sponge, welding pieces into an electrode and then melting it into
an ingot in a high vacuum arc furnace. High purity ingots require
multiple arc melting operations. Powder titanium is usually
produced from the sponge through grinding, shot casting or
centrifugal processes. A common technique is to first react the
titanium with hydrogen to make brittle titanium hydride to
facilitate the grinding process. After formation of the powder
titanium hydride, the particles are dehydrogenated to produce a
usable metal powder product. The processing of the titanium sponge
into a usable form is difficult, labor intensive, and increases the
product cost by a factor of two to three.
[0007] The processes discussed above have several intrinsic
problems that contribute heavily to the high cost of titanium
production. Batch process production is inherently capital and
labor intensive. Titanium sponge requires substantial additional
processing to produce titanium in a usable form; thereby increasing
cost, increasing hazard to workers and exacerbating batch quality
control difficulties. Neither process utilizes the large exothermic
energy reaction, requiring substantial energy input for titanium
production (approximately 6 kW-hr/kg product metal). In addition,
the processes generate significant production wastes that are of
environmental concern.
SUMMARY OF THE INVENTION
[0008] Accordingly, an object of the present invention is to
provide a method and system for producing non-metals or metals or
alloys thereof which is continuous having significant capital and
operating costs advantages over existing batch technologies.
[0009] Another object of the present invention is to provide an
improved batch or semi-batch process for producing non-metals or
metals or alloys thereof where continuous operations are not
warranted by the scale of the production.
[0010] Another object of the present invention is to provide a
method and system for producing metals and non-metals from the
exothermic reduction of the halide while preventing the metal or
non-metal from sintering into large masses or onto the apparatus
used to produce same.
[0011] Still another object of the invention is to provide a method
and system for producing non-metal or metal from the halides
thereof wherein the process and system recycles the reducing agent
and removes the heat of reaction for use as process heat or for
power generation, thereby substantially reducing the environmental
impact of the process.
[0012] The invention consists of certain novel features and a
combination of parts hereinafter fully described, illustrated in
the accompanying drawings, and particularly pointed out in the
appended claims, it being understood that various changes in the
details may be made without departing from the spirit, or
sacrificing any of the advantages of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For the purpose of facilitating an understanding of the
invention, there is illustrated in the accompanying drawings a
preferred embodiment thereof, from an inspection of which, when
considered in connection with the following description, the
invention, its construction and operation, and many of its
advantages should be readily understood and appreciated.
[0014] FIG. 1 is a process flow diagram showing the continuous
process for producing as an example titanium metal from titanium
tetrachloride;
[0015] FIG. 2 is an example of a burner reaction chamber for a
continuous process;
[0016] FIG. 3 is a process diagram of a batch process reaction;
and
[0017] FIG. 4 is a diagram of the apparatus used to produce
titanium.
[0018] FIG. 5 is a SEM of Ti powder made by the process of the '761
and '106 patents;
[0019] FIG. 6 is a SEM of Ti powder made in accordance with the
process set forth in the '761 and '106 patents;
[0020] FIG. 7 is a SEM of a Ti alloy made in accordance with the
process set forth in the '761 and '106 patents; and
[0021] FIG. 8 is a SEM of a Ti alloy made in accordance with the
process set forth in the '761 and '106 patents.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The process of the invention may be practiced with the use
of any alkali or alkaline earth metal depending upon the metal or
non-metal to be reduced. In some cases, combinations of an alkali
or alkaline earth metals may be used. Moreover, any halide or
combinations of halides may be used with the present invention
although in most circumstances chlorine, being the cheapest and
most readily available, is preferred. Of the alkali or alkaline
earth metals, by way of example, sodium will be chosen not for
purposes of limitation but merely purposes of illustration, because
it is cheapest and preferred, as has chlorine been chosen for the
same purpose.
[0023] Regarding the non-metals or metals to be reduced, it is
possible to reduce a single metal such as titanium or tantalum or
zirconium, selected from the list set forth hereafter. It is also
possible to make alloys of a predetermined composition by providing
mixed metal halides at the beginning of the process in the required
molecular ratio. By way of example, Table 1 sets forth heats of
reaction per gram of liquid sodium for the reduction of a
stoichiometric amount of a vapor of a non-metal or metal halides
applicable to the inventive process.
TABLE-US-00001 TABLE 1 FEEDSTOCK HEAT kJ/g TiCl.sub.4 10 AlCL.sub.3
9 SnCl.sub.2 4 SbCl.sub.3 14 BeCl.sub.2 10 BCl.sub.3 12 TaCl.sub.5
11 ZrCl.sub.4 9 VCl.sub.4 12 NbCl.sub.5 12 MoCl.sub.4 14 GaCl.sub.3
11 UF.sub.6 10 ReF.sub.6 17
The process will be illustrated, again for purposes of illustration
and not for limitation, with a single metal titanium being produced
from the tetrachloride.
[0024] A summary process flowsheet is shown in FIG. 1. Sodium and
titanium tetrachloride are combined in a reaction chamber 14 where
titanium tetrachloride vapor from a source thereof in the form of a
boiler 22 is injected within a flowing sodium stream from a
continuously cycling loop thereof including a sodium pump 11. The
sodium stream is replenished by sodium provided by an electrolytic
cell 16. The reduction reaction is highly exothermic, forming
molten reaction products of titanium and sodium chloride. The
molten reaction products are quenched in the bulk sodium stream.
Particle sizes and reaction rates are controlled by metering of the
titanium tetrachloride vapor flowrate (by controlling the supply
pressure), dilution of the titanium tetrachloride vapor with an
inert gas, such as He or Ar, and the sodium flow characteristics
and mixing parameters in the reaction chamber which includes a
nozzle for the titanium tetrachloride and a surrounding conduit for
the liquid sodium. The vapor is intimately mixed with the liquid in
a zone enclosed by the liquid, i.e., a liquid continuum, and the
resultant temperature, significantly affected by the heat of
reaction, is controlled by the quantity of flowing sodium and
maintained below the sintering temperature of the produced metal,
such as for titanium at about 1000.degree. C. Preferably, the
temperature of the sodium away from the location of halide
introduction is maintained in the range of from about 200.degree.
C. to about 600.degree. C. Products leaving the reaction zone are
quenched in the surrounding liquid before contact with the walls of
the reaction chamber and preferably before contact with other
product particles. This precludes sintering and wall erosion.
[0025] The surrounding sodium stream then carries the titanium and
sodium chloride reaction products away from the reaction region.
These reaction products are removed from the bulk sodium stream by
conventional separators 15 such as cyclones, particulate filters,
magnetic separators or vacuum stills.
[0026] Three separate options for separation of the titanium and
the sodium chloride exist. The first option removes the titanium
and sodium chloride products in separate steps. This is
accomplished by maintaining the bulk stream temperature such that
the titanium is solid but the sodium chloride is molten through
control of the ratio of titanium tetrachloride and sodium flowrates
to the reaction chamber 14. For this option, the titanium is
removed first, the bulk stream cooled to solidify the sodium
chloride, then the sodium chloride is removed from separator
[0027] In the second option for reaction product removal, a lower
ratio of titanium tetrachloride to sodium flowrate would be
maintained in the reaction chamber 14 so that the bulk sodium
temperature would remain below the sodium chloride solidification
temperature. For this option, titanium and sodium chloride would be
removed simultaneously using conventional separators. The sodium
chloride and any residual sodium present on the particles would
then be removed in a water-alcohol wash.
[0028] In the third, and preferred option for product removal, the
solid cake of salt, Ti and Na is vacuum distilled to remove the Na.
Thereafter, the Ti particles are passivated by passing a gas
containing some O.sub.2 over the mixture of salt and Ti followed by
a water wash to remove the salt leaving Ti particles with surfaces
of TiO.sub.2, which can be removed by conventional methods.
[0029] Following separation, the sodium chloride is then recycled
to the electrolytic cell 16 to be regenerated. The sodium is
returned to the bulk process stream for introduction to reaction
chamber 14 and the chlorine is used in the ore chlorinator 17. It
is important to note that while both electrolysis of sodium
chloride and subsequent ore chlorination will be performed using
technology well known in the art, such integration and recycle of
the reaction by-product directly into the process is not possible
with the Kroll or Hunter process because of the batch nature of
those processes and the production of titanium sponge as an
intermediate product. In addition, excess process heat is removed
in heat exchanger 10 for co-generation of power. The integration of
these separate processes enabled by the inventive chemical
manufacturing process has significant benefits with respect to both
improved economy of operation and substantially reduced
environmental impact achieved by recycle of both energy and
chemical waste streams.
[0030] Chlorine from the electrolytic cell 16 is used to chlorinate
titanium ore (rutile, anatase or ilmenite) in the chlorinator 17.
In the chlorination stage, the titanium ore is blended with coke
and chemically converted in the presence of chlorine in a
fluidized-bed or other suitable kiln chlorinator. The titanium
dioxide contained in the raw material reacts to form titanium
tetrachloride, while the oxygen forms carbon dioxide with the coke.
Iron and other impurity metals present in the ore are also
converted during chlorination to their corresponding chlorides. The
titanium chloride is then condensed and purified by means of
distillation in column 18. With current practice, the purified
titanium chloride vapor would be condensed again and sold to
titanium manufacturers; however, in this integrated process, the
titanium tetrachloride vapor stream is used directly in the
manufacturing process via a feed pump 21 and boiler 22.
[0031] After providing process heat for the distillation step in
heat exchangers 19 and 20, the temperature of the bulk process
stream is adjusted to the desired temperature for the reaction
chamber 14 at heat exchanger 10, and then combined with the
regenerated sodium recycle stream, and injected into the reaction
chamber. The recovered heat from heat exchangers 19 and 20 may be
used to vaporize liquid halide from the source thereof to produce
halide vapor to react with the metal or the non-metal. It should be
understood that various pumps, filters, traps, monitors and the
like will be added as needed by those skilled in the art.
[0032] In all aspects, for the process of FIG. 1, it is important
that the titanium that is removed from the separator 15 be at or
below the sintering temperature of titanium in order to preclude
and prevent the solidification of the titanium on the surfaces of
the equipment and the agglomeration of titanium particles into
large masses, which is one of the fundamental difficulties with the
commercial processes used presently. By maintaining the temperature
of the titanium metal below the sintering temperature of titanium
metal, the titanium will not attach to the walls of the equipment
or itself as it occurs with prior art and, therefore, the physical
removal of the same will be obviated. This is an important aspect
of this invention and is obtained by the use of sufficient sodium
metal or diluent gas or both to control the temperature of the
elemental (or alloy) product. In other aspects, FIG. 1, is
illustrative of the types of design parameters which may be used to
produce titanium metal in a continuous process which avoids the
problems with the prior art. Referring now to FIG. 2, there is
disclosed a typical reaction chamber in which a choke flow or
injection nozzle 23, completely submerged in a flowing liquid metal
stream, introduces the halide vapor from a boiler 22 in a
controlled manner into the liquid metal reductant stream 13. The
reaction process is controlled through the use of a choke-flow
(sonic or critical flow) nozzle. A choke-flow nozzle is a vapor
injection nozzle that achieves sonic velocity of the vapor at the
nozzle throat. That is the velocity of the vapor is equal to the
speed of sound in the vapor medium at the prevailing temperature
and pressure of the vapor at the nozzle throat. When sonic
conditions are achieved, any change in downstream conditions that
causes a pressure change cannot propagate upstream to affect the
discharge. The downstream pressure may then be reduced indefinitely
without increasing or decreasing the discharge. Under choke flow
conditions only the upstream conditions need to be controlled to
control the flow-rate. The minimum upstream pressure required for
choke flow is proportioned to the downstream pressure and termed
the critical pressure ratio. This ratio may be calculated by
standard methods.
[0033] The choke flow nozzle serves two purposes: (1) it isolates
the vapor generator from the liquid metal system, precluding the
possibility of liquid metal backing up in the halide feed system
and causing potentially dangerous contact with the liquid halide
feedstock, and (2) it delivers the vapor at a fixed rate,
independent of temperature and pressure fluctuations in the
reaction zone, allowing easy and absolute control of the reaction
kinetics.
[0034] The liquid metal stream also has multiple functional uses:
(1) it rapidly chills the reaction products, forming product powder
without sintering, (2) it transports the chilled reaction products
to a separator, (3) it serves as a heat transfer medium allowing
useful recovery of the considerable reaction heat, and (4) it feeds
one of the reactants to the reaction zone.
[0035] For instance in FIG. 2, the sodium 13 entering the reaction
chamber is at 200.degree. C. having a flow rate of 38.4 kilograms
per minute. The titanium tetrachloride from the boiler 22 is at 2
atmospheres and at a temperature of 164.degree. C., the flow rate
through the line was 1.1 kg/min. Higher pressures may be used, but
it is important that back flow be prevented, so the minimum
pressure should be above that determined by the critical pressure
ratio for sonic conditions, or about two times the absolute
pressure of the sodium stream (two atmospheres if the sodium is at
atmospheric pressure) is preferred to ensure that flow through the
reaction chamber nozzle is critical or choked.
[0036] The batch process illustrated in FIG. 3 shows a subsurface
introduction of titanium tetrachloride vapor through an injection
or an injector or a choke flow nozzle 23 submerged in liquid sodium
contained in a reaction vessel 24. The halide vapor from the boiler
22 is injected in a controlled manner where it reacts producing
titanium powder and sodium chloride. The reaction products fall to
the bottom of the tank 25 where they are collected for removal. The
tank walls are cooled via cooling colis 24 and a portion of the
sodium in the tank is pumped out via pump 11 and recycled through a
heat exchanger 10 and line 5 back to the tank to control the
temperature of the sodium in the reaction vessel. Process
temperatures and pressures are similar to the continuous flow case
with bulk sodium temperature of 200.degree. C., titanium
tetrachloride vapor of 164.degree. C., and the feed pressure of the
titanium tetrachloride vapor about twice the pressure in the
reaction vessel.
[0037] In the flow diagrams of FIGS. 1 and 3, sodium make-up is
indicated by the line 13 and this may come from an electrolytic
cell 16 or some other entirely different source of sodium. In other
aspects, FIG. 3 is illustrative of the types of design parameters
which may be used to produce titanium metal in a batch process
which avoids agglomeration problems inherent in the batch process
presently in use commercially.
Brief Description of the Production of Titanium
[0038] FIG. 4 shows a schematic depiction of a loop used to produce
titanium metal powder. The parts of the loop of most importance to
the operation are a large (10 liter) reaction vessel 29 with a
collection funnel 28 at the bottom feeding into a recycle stream.
The recycle stream has a low volume, low head, electromagnetic pump
11 and a flow meter 25.
[0039] A titanium tetrachloride injection system consisted of a
heated transfer line, leading from a heated tank 30 with a large
heat capacity, to a submerged choke flow nozzle 23. The system
could be removed completely from the sodium loop for filling and
cleaning. It should be understood that some commercial grades of Na
have Ca or other alkaline earth metals therein. This has no
substantial affect on the invention.
Operation
[0040] A typical operating procedure follows: [0041] 1. Raise
temperature of sodium loop to desired point (200.degree. C.).
[0042] 2. Open titanium tetrachloride tank and fill with titanium
tetrachloride. [0043] 3. Insert the nozzle into the airlock above
the ball valve 33. [0044] 4. Heat titanium tetrachloride tank to
desired temperature (168.degree. C.) as determined by vapor
pressure curve (2 atm.) and the required critical flow pressure.
[0045] 5. Start an argon purge through the nozzle. [0046] 6. Open
ball valve 33 and lower the nozzle into sodium. [0047] 7. Stop the
purge and open valve 32 allowing titanium tetrachloride to flow
through the nozzle into the sodium. [0048] 8. When titanium
tetrachloride pressure drops close to the critical pressure ratio,
close the valve 32 and withdraw the nozzle above valve 33. [0049]
9. Close valve 33 and let the nozzle cool to room temperature.
[0050] 10. Remove the titanium tetrachloride delivery system and
clean.
[0051] The injection of titanium tetrachloride was monitored by
measuring the pressure in the titanium tetrachloride system. A
pressure transducer 31 was installed and a continuous measurement
of pressure was recorded on a strip chart.
[0052] A filtration scheme was used to remove products from the
bulk sodium at the end of the test. The recycle stream system was
removed from the sodium loop. In its place, a filter 26 consisting
of two 5 cm diameter screens with 100 .mu.m holes in a housing 20
cm long, was plumbed into a direct line connecting the outlet of
the reaction vessel to the sodium receiver tank. All of the sodium
was transferred to the transfer tank 27.
[0053] The reaction product was washed with ethyl alcohol to remove
residual sodium and then passivated with an oxygen containing gas
and washed with water to remove the sodium chloride by-product.
Particle size of the substantially pure titanium ranged between
about 0.1 and about 10 .mu.m with a mean size of about 5.5 .mu.m.
The titanium powder produced in the apparatus was readily separable
from the sodium and sodium chloride by-product.
[0054] The invention has been illustrated by reference to titanium
alone and titanium tetrachloride as a feedstock, in combination
with sodium as the reducing metal. However, it should be understood
that the foregoing was for illustrative purposes only and the
invention clearly pertains to those metals and non-metals in Table
1, which of course include the fluorides of uranium and rhenium and
well as other halides such as bromides. Moreover, sodium while
being the preferred reducing metal because of cost and
availability, is clearly not the only available reductant. Lithium,
potassium as well as magnesium, calcium and other alkaline earth
metals are available and thermodynamically feasible. Moreover,
combinations of alkali metals and alkaline earth metals have been
used, such as Na and Ca. The two most common reducing agents for
the production of Ti are Na and Mg, so mixtures of these two metals
may be used, along with Ca, which is present in some Na as a by
product of the method of producing Na. It is well within the skill
of the art to determine from the thermodynamic Tables which metals
are capable of acting as a reducing agent in the foregoing
reactions, the principal applications of the process being to those
illustrated in Table 1 when the chloride or halide is reduced to
the metal. Moreover, it is well within the skill of the art and it
is contemplated in this invention that alloys can be made by the
process of the subject invention by providing a suitable halide
feed in the molecular ratio of the desired alloy.
[0055] In the process described in the '761 patent, FIG. 2 and the
description thereof as well as in the '106 patent, FIG. 2 and the
description thereof as well as in FIG. 2 and the description
thereof in the parent application Ser. No. 09/264,877, there is
inherently produced Ti powder and Ti alloy powder having unique
properties. More particularly, the Ti inherently produced has an
iron concentration of less than 200 ppm as measured by ICPQ; a
nitrogen concentration of less than 200 ppm, and a hydrogen
concentration of less than about 100 ppm as measured by a LECO gas
analyzer. The Ti powder inherently produced by the process
mentioned in this paragraph is encrusted with NaCl, when formed,
but when thoroughly washed to remove the NaCl, the remaining Ti
powder has a chlorine concentration of less than 100 ppm as
measured by neutron activation analysis.
[0056] Moreover, the Ti powder inherently produced after washing
and separation has a packing fraction of between about 4% to about
11% as determined by a tap density measurements in which the Ti
powder is introduced into a graduated test tube and tapped until
the powder is fully settled. Thereafter, the weight of the powder
is measured and the packing fraction or percent of theoretical
density is calculated.
[0057] In addition, the Ti powder inherently produced has a BET
surface area ranging from 0.4 m.sup.2/gm for a sample of the
largest particles to about 6.4 m.sup.2/gm for a sample of the
smallest particles or fines. With fines separated from the
material, the BET surface area for samples is in the range of about
0.4 to about 1.0 m.sup.2/gm. Calculation of the particle diameters
based on the BET surface area and assuming spherical shape results
in particle diameters in the range of from about 3.3 to about 1.3
microns when the fines have been removed. By separation of fines,
we mean that a sample of particles produced by the inventive method
which do not readily settle in minutes are classified as fines.
During the production of the Ti powder by the inventive method both
agglomerated particles and unagglomerated particles are inherently
produced. For instance, when the Na temperature after the reaction
downstream of the tip of nozzle 23 is near 350.degree. C., the
agglomerates are small on average about 0.2 mm in any one
direction, whereas when the Na temperature after the reaction
downstream of the top of nozzle 23 is higher, for instance about
450.degree. C., the agglomerates are larger, on average of about
1.6 mm in any one direction.
[0058] Prior art Ti powder has been made by one of two processes,
either a hydride/dehydride process which produced flake shaped
powder or a process in which Ti is melted followed by atomization
which results in spherical shaped powders. Low quality (high
impurity) fines are produced in the Hunter process. The Ti and Ti
alloy powder inherently made by the process disclosed herein is
neither flake-shaped nor spherical shaped, as defined in Powder
Metallurgy Science, by Randall M. German, second edition,
.COPYRGT.Metal Powder Industries Federation 1984, 1994 page 63, a
standard reference book. Morphology as used herein includes powder
shape and size. The morphology of the powder illustrated in FIG. 5
is unlike any Ti powder known to the applicants, including Hunter
fines. With reference to FIG. 5, the large shiny globes and
crystals are NaCl, not the titanium produced according to the
method of the '761 and '106 patents. FIG. 6 is another SEM of Ti
powder made in accordance with the process set forth in the '761
and '106 patents, also at 3000 magnification as is FIG. 5.
[0059] FIGS. 7 and 8 are SEMs of Ti alloy made in accordance with
the process of the '761 and '106 patents; however, these SEMs are
at 5000 and at 10,000 magnification, respectively. These SEMs (5-8)
are different morphologically with respect to the powders made and
distilled as taught in U.S. Pat. No. 6,409,797 using distillation
to separate excess Na from the reaction products and
morphologically different from other Ti powders known to
applicants.
[0060] It has been well known in the powder metallurgy art prior to
Aug. 1, 1994, how to convert metal powder to solid shapes by a
variety of processes, such as powder metallurgy using press and
sinter methods, powder injection molding, metal injection molding,
powder to plate, continuous casting techniques by way of example,
only. These well known methods, prior to Aug. 1, 1994, had been
used to convert titanium powder to solid product as well as a wide
variety of other metals and metal alloy powders.
[0061] While there has been disclosed what is considered to be the
preferred embodiment of the present invention, it is understood
that various changes in the details may be made without departing
from the spirit, or sacrificing any of the advantages of the
present invention.
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