U.S. patent application number 13/661922 was filed with the patent office on 2014-04-10 for process for the recovery of ab5 alloy from used nickel/metal hydride batteries.
This patent application is currently assigned to Toxco, Inc.. The applicant listed for this patent is Toxco, Inc.. Invention is credited to W. NOVIS SMITH, SCOTT SWOFFER.
Application Number | 20140096647 13/661922 |
Document ID | / |
Family ID | 50431692 |
Filed Date | 2014-04-10 |
United States Patent
Application |
20140096647 |
Kind Code |
A1 |
SMITH; W. NOVIS ; et
al. |
April 10, 2014 |
Process for the Recovery of AB5 Alloy from Used Nickel/Metal
Hydride Batteries
Abstract
There is provided a process for recovering AB.sub.5 alloy from
spent nickel hydride storage batteries and/or their cells without
thermal melting or dissolving the AB.sub.5 alloy. The process
comprises a step of dissolving the Ni(OH).sub.2 and separating
AB.sub.5 alloy and still containing the lanthanum metal.
Inventors: |
SMITH; W. NOVIS;
(Philadelphia, PA) ; SWOFFER; SCOTT; (New Castle,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Toxco, Inc. |
Anaheim |
CA |
US |
|
|
Assignee: |
Toxco, Inc.
Anaheim
CA
|
Family ID: |
50431692 |
Appl. No.: |
13/661922 |
Filed: |
October 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13066103 |
Apr 6, 2011 |
8252085 |
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13661922 |
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12806877 |
Aug 23, 2010 |
8246717 |
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13066103 |
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Current U.S.
Class: |
75/403 |
Current CPC
Class: |
C01B 3/0068 20130101;
C22B 59/00 20130101; Y02E 60/10 20130101; C22B 7/007 20130101; Y02E
60/32 20130101; Y02W 30/84 20150501; H01M 4/385 20130101; C22B
23/00 20130101; C22B 1/005 20130101; Y02P 10/20 20151101; H01M
10/54 20130101; H01M 4/242 20130101 |
Class at
Publication: |
75/403 |
International
Class: |
C22B 1/00 20060101
C22B001/00 |
Claims
1. A process for the recovery of AB.sub.5 intermetallic alloy from
spent nickel metal hydride batteries and cells which comprises the
steps of: A) wet crushing nickel metal hydride batteries and cells;
B) screening the product of step A) to separate metal particles
from the slurry which is formed; C) treating the slurry from step
B) with a non-oxidizing non-halogenated acid to selectively
dissolve the nickel hydroxide in the slurry without dissolving the
AB.sub.5 alloy; and then D) recovering the AB.sub.5 alloy.
2. The process of claim 1 wherein the process is conducted in an
inert atmosphere.
3. The process of claim 1 wherein step B) comprises screening
through a 25 mesh screen and then through a -200 mesh screen.
4. The process of claim 1 wherein the AB.sub.5 alloy recovered
contains lanthanum.
5. The process of claim 1 wherein the non-oxidizing non-halogenated
acid of step C) is selected from the group consisting of acetic
acid, glycolic acid, formic acid and sulfuric acid.
6. The process of claim 1 which comprises dissolving the nickel
hydroxide in step C) at a pH of 2-5.
7. The process of claim 6 wherein the slurry from step B) is
neutralized at pH 5.
8. The process of claim 1 wherein in step D) AB.sub.5 alloy is
recovered by allowing the AB.sub.5 alloy to settle and decanting
off a solution from the settled AB.sub.5 alloy, and comprising the
additional steps of filtering the solution to form a filtrate and
treating the filtrate with a sodium hydroxide solution to pH 10-11
to precipitate nickel hydroxide.
9. The process of claim 1 wherein the electrodes of nickel metal
hydroxide batteries are crushed.
10. The process of claim 1, wherein step C) comprises adding a
non-oxidizing non-halogenated acid in estimated 50-95% of theory
amount to dissolve the calculated molar amount of nickel hydroxide
present.
11. The process of claim 1 wherein in step D) AB.sub.5 alloy is
recovered by allowing the AB.sub.5 alloy to settle and decanting
off a solution from the settled AB.sub.5 alloy.
12. The process of claim 11, comprising an additional step after
decanting of washing the settled AB.sub.5 alloy.
13. The process of claim 11, comprising additional steps after
decanting of washing, filtering and drying the settled AB.sub.5
alloy.
14. The process of claim 1, wherein recovery of the AB.sub.5 alloy
is accomplished in a continuous controlled cyclic wash with
filtration of the circulating system.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the recovery of AB.sub.5
alloy from spent nickel/metal hydride (NIMH) storage batteries
and/or the electrode cells. More particularly, there is provided a
process for the selective recovery of AB.sub.5 alloy from NIMH
storage batteries without thermal melting or dissolving the
AB.sub.5 alloy into solution.
BACKGROUND OF THE INVENTION
[0002] There are a number of processes described in the literature
and patents for recycling NIMH batteries to recover the valuable
nickel values contained in them as nickel metal grid, nickel plated
foil, the nickel hydroxide in the cathode with some cobalt
hydroxide and the nickel metal powder present in the anode as a
nickel metal alloy with rare earth metals. Up to now the recovery
processes have focused only on the nickel values which allowed for
direct smelting of these batteries in furnaces as part of the feed
for making high nickel alloys. The rare earth metals react under
these conditions to form the rare earth oxides similar to how they
are found in nature and end up in the molten oxide slag which is
thrown away. More recently, processes have been described where
these batteries are carefully melted and the slag volume and nature
are controlled to end up with a richer rare earth slag more
suitable for recovering the rare earths from the slag in the same
way they are recovered by current production processes from rare
ores. Another way that is being developed is the total solution of
the isolated NIMH electrode materials to produce solutions of the
nickel, cobalt and the rare-earth salt mixtures. These solutions
are then processed by normal hydrometallurgical methods to separate
the solution components into the nickel hydroxide (or carbonate),
cobalt hydroxide (or carbonate) and the rare earth separated into a
separate mixed rare earth component for processing on a standard
rare earth oxide separation process line associated with rare earth
ore processing. The reason for this change in the expansion of
these recycle processes to recover the rare earth oxides is that
the world supply of these oxides is 95% controlled by China and the
use for rare earth compounds continues to expand. This has caused
supply of rare earth to become tight and probably to remain so with
the associated increase in the value of these materials.
[0003] The rare earths material are found in the NIMH battery in
the unique hydrogen absorbing AB.sub.5 metal alloy anode (about 32%
are earth metals primarily lanthanum-25%) powder which is the key
anode material found in most NIMH batteries. There is a significant
amount of energy and loss material in separating then converting a
rare-earth ore to the purified rare earth compound mix (25%
lanthanum). The correct rare earth oxide mix is converted to the
highly reactive rare earth metal mixture (Misch metal) under vacuum
and very high temperatures (>1400.degree. C.) under vacuum. This
Misch metal then must be mixed with the correct amount of nickel
metal and re-melted in a vacuum induction furnace and then cooled
rapidly and then ground to a -325 mesh powder under inert
atmosphere due to its reactivity. The very hard alloy is difficult
to grind. This is a very energy intensive and costly process.
[0004] The invention is more preferably used in a cell containing a
negative electrode having hydrogen storage alloy materials of the
so-called AB.sub.5-type, a common example of which is described in
the basic formula M.sub.sNiAl.sub.xMn.sub.4Co.sub.3 and
M.sub.sNi.sub.5(Al.sub.xMn.sub.4Co.sub.3).sub.x wherein M.sub.s
represents a lanthanum-rich misch metal (REM), which includes
various rare earth metals and wherein 2.5<r<5.0,
0<s<2.5, 0<t<0.5, and 0<u<0.5. Hydrogen absorbing
alloys of this class (i.e., AB.sub.5) are disclosed, for instance,
in U.S. Pat. No. 4,216,274 (Bruning et al) and U.S. Pat. No.
4,375,257 (Bruning, et al).
[0005] The typical AB.sub.2-type materials, as currently
envisioned, are based on TiNi.sub.2 and typically have the basic
atomic structure Ni--Ti--V--Cr--Zr--X--Y wherein X and Y can be
other elements of various selection. The invention is more
preferably used in a cell containing a negative electrode having
hydrogen storage intermetallic alloy materials of the so-called
AB.sub.5-type, a common example of which are described in the basic
formula MmNi.sub.rCo.sub.sMn.sub.tAl.sub.u, wherein Mm represents a
lanthanum-rich misch metal, which includes various rare earth
metals, and wherein 2.5<r<5.0, 0<s<2.5, 0<t<0.5,
and 0<u<0.5 and M.sub.sNiAl.sub.xMn.sub.4Co.sub.3.
[0006] Negative electrode alloys used in NiMH batteries typically
comprise La, Pr and Nd as rare earth elements and Zn, Mg and Ni.
Cobalt, manganese and aluminum are common additives.
[0007] The components of the NIMH battery include nickel metal
grid, Ni(OH).sub.2, nickel coated iron, potassium hydroxide
electrolyte, and most importantly a nickel metal alloy powder of up
to 25-30% by weight. This alloy powder has been developed to absorb
considerable hydrogen and is the source of the descriptor "nickel
metal hydride" battery. Under charging conditions this nickel alloy
absorbs significant amounts of hydrogen as the metal hydride is
formed electrochemically. Under battery discharge conditions this
absorbed hydrogen reacts electrochemically back to hydroxide and
water providing the electrical current of the battery. The
currently most well known nickel alloy used is termed AB.sub.S
which is an alloy consisting of one part misch metal (mostly
lanthanum or REM) to five parts nickel on a mole
basis--theoretically 32.1% (REM) on a weight basis. Therefore the
naturally occurring rare earth oxide mixture is used to form the
misch metal which avoids the expense of separating the rare earth
oxides into the individual elements before reducing them to the
mixed metal and not to the pure metal such as pure lanthanum metal.
This metal mixture is used which is called misch metal. Therefore
the AB.sub.5 alloy is an alloy of a mixture of lanthanum group
metals and nickel with some cobalt and other metals added in small
amounts for optimized hydrogen formation and storage. This AB.sub.5
component is the most expensive raw material cost for this
battery.
SUMMARY OF THE INVENTION
[0008] According to the present invention there is provided a
method for the purification of a mixture of hydrogen storage
intermetallic alloy AB.sub.5 obtained from the crushed nickel metal
hydride batteries and the electrodes of spent nickel metal hydride
batteries together with any lanthanum present and optionally, the
separate recovery of Ni(OH).sub.2 which is present. The process
comprises the steps of (a) wet crushing nickel metal hydride
batteries and cells, (b) screening the product of step (a) to
recover metal particles and the resultant slurry, selectively
dissolving Ni(OH).sub.2 at a pH of about 2-5 without dissolving the
AB.sub.S intermetallic alloy and lanthanum; (c) filtering the
product of step (b) and washing the solids; and then (d) drying the
solids under an inert atmosphere and recovering the AB.sub.S and
lanthanum. Advantageously, the Ni(OH).sub.2 is selectively
dissolved by a non-oxidizing non-halogenated acid.
[0009] It is therefore a general object of the invention to purify
a mixture containing hydrogen storage intermetallic AB.sub.5 which
is obtained from the electrodes of spent nickel metal hydride
batteries or the crushed batteries.
[0010] It is a further object of the invention to obtain AB.sub.5
and lanthanum from electrodes of spent nickel metal hydride
batteries.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] According to the invention there is provided a method for
the purification and isolation of hydrogen storage intermetallic
alloy AB.sub.5 and any lanthanum present from material obtained
from spent nickel metal hydride batteries and cells which comprises
the steps of: [0012] A) wet crushing nickel metal hydride batteries
and cells; [0013] B) screening the product of step A) to recover
the metal particles and the slurry formed, [0014] C) selectively
dissolving the nickel hydroxide in the slurry with a non-oxidizing
non-halogenated acid without dissolving said intermetallic alloy
AB5 and any lanthanum present; and then [0015] D) recovering the
solids.
[0016] Advantageously, the process is carried out under an inert
atmosphere.
[0017] The non-oxidizing non-halogenated acid is preferably
selected from the group consisting of acetic acid, glycolic acid,
formic acid and sulfuric acid.
[0018] The product of Step B) can be screened through a 25 mesh
screen and then through a -200 mesh screen.
[0019] Advantageously step C) is carried out at a pH of 2-4.
[0020] The present process consists of the crushing of the steel
cased battery or cells in a water mist preferably in a hammer mill
and under an inert atmosphere. The wet heavy separator mat which
entangles much of the coarse grid collector metal on the top of a
shaker table (+1/4'') is screened off. This is sold for its coarse
nickel metal content. It can also be pyrolyzed to remove the
organic separator yielding all of the contained nickel metal powder
and pieces free of organic material also for sale.
[0021] The rest of the water slurry after removing the +1/4''
material is further screened to -200 mesh to yield a slurry
containing 85% of the starting electrode material including the
AB.sub.5 anode metal powder material and the nickel hydroxide
cathode material with some binder. This -200 mesh slurry is
neutralized to pH 5 with the non-oxidizing acid such as glycolic
acid. At this point 70% glycolic acid (commercial grade) is
preferably added to the aqueous slurry under an inert atmosphere in
an estimated 50-95% of theory amount to dissolve the calculated
molar mount of nickel hydroxide present (2 moles of glycolic acid
per mole of nickel hydroxide). This addition is at room temperature
with high shear stirring and cooling is maintained about
18-25.degree. C. for four hours. The slurry is allowed to settle
briefly to just allow the dense AB.sub.S to settle. The solution
containing the dissolved nickel glycolate or other acid salt (with
some cobalt glycolate) both from the cathode and a light brown haze
from the liberated organic binder is decanted off and filtered. The
nickel hydroxide is recovered from this solution by adding 50%
sodium hydroxide to pH 10-11 and filtering the nickel hydroxide off
and drying. The glycolic acid is recovered from this filtrate for
recycling back to the process by acidifying this filtrate with
sulfuric acid to pH 1-2 and distilling off the water and then the
glycolic acid azeotrope.
[0022] The wash decantation of the AB.sub.5 metal powder may be
needed several times to purge the residual binder from the AB.sub.5
powder. (This can also be accomplished in a continuous controlled
cyclic wash with filtration of the circulating system). The cleaned
AB.sub.5 is filtered and recovered under inert atmosphere. It is
dried under vacuum at 100.degree. C., cooled and screened through
-325 mesh. The assay is 25% La and an oxygen content of <1.0%.
The other rare earths including the cerium and yunum add up to
about 6% with a few percent cobalt and aluminum. The nickel metal
is the balance to about 65%. The overall recovery from the
electrode is about 50-80% of the contained AB.sub.5 metal in the
electrode mix.
[0023] The initial slurry after screening the metal particles may
be treated with a magnet to remove any small casing particles.
[0024] This selective dissolution/purification procedure will work
on any mixture of the nickel metal hydride and the Ni(OH).sub.2
cathode material. It can be applied to those mixtures recovered
from the processing and recycling of NIMH batteries. It can also be
applied to electrode powders recovered from nickel/hydrogen
batteries.
[0025] The following examples serve to explain the invention in
more detail, where the examples are intended to facilitate
understanding of the principle according to the invention and are
not to be understood as meaning a limitation thereof.
EXAMPLE 1
[0026] Ten Prius NIMH battery cells (1510 g) were stripped of their
bus bars and plastic covers (1155 g after) were run through a
hammer mill with an internal water spray and under nitrogen. The
slurry was directed onto a shaker table with 1/4'' slots and the
slurry passed through a 25 mesh screen (72 g +25 mesh -1/4'') and
then through a -200 mesh screen (61 g +200 mesh/-25 mesh). The damp
mat cake on the shaker table contained coarse metal pieces and
weighed 262 g dry. (Pyrolysis of this mat at 280.degree. C. under
inert atmosphere gave 220 g of nickel metal powder and pieces for
recovery.) The -200 mesh slurry was filtered to reduce the water
content and dried under vacuum. This mixed electrode cake
consisting of AB.sub.5 metal powder and nickel hydroxide cathode
material weighed 564 g dry. (All steps were processed under
nitrogen when possible.) The dry cake contained 12% lanthanum which
serves as marker for the purity of the AB.sub.5 which contains
about 25%-26% lanthanum. This cake was about 48% AB.sub.5 at this
point of recovery.
[0027] This electrode mix was processed by the addition of slightly
less than stoichiometric amounts (0.5 to 0.9) of 70% glycolic acid
(in mole ratios of two glycolic acid molecules for each nickel
hydroxide molecule present). The analysis of the lanthanum level
was indicative of the purity along with the oxygen level.
EXAMPLE 2
[0028] A slurry of 80 g of the electrode mix (12% La) was slurried
in 200 ml of water with high speed mixing under nitrogen.
(Calculated to contain 41.6 g nickel hydroxide-0.45 moles). The
slurry was adjusted to pH 5 with sulfuric acid and then 78 g (70%)
glycolic acid (85% of theory) was slowly added with only slight
warm up. The stifling was maintained four hours and then the slurry
was allowed to settle only enough to allow the dense AB.sub.5 to
settle but to keep the fine brown gelatinous binder particles
suspended. The total solution and binder were decanted off. This
was repeated three times. The AB.sub.5 was isolated by filtration
and drying under vacuum and finally screening through -325 mesh. A
magnet was used to remove any nickel metal fines which may still be
present. The La was 25% with 0.89% oxygen and the yield was 26 g
which was 68% based on the calculated amount in the cake.
EXAMPLE 3
[0029] A slurry of 80 g of the electrode mix (12% La) was slurried
in 200 ml of water with high speed mixing under nitrogen.
(Calculated to contain 41.6 g nickel hydroxide-0.45 moles). The
slurry was adjusted to pH 5 with sulfuric acid and then 64 g
glycolic acid (70% of theory) was slowly added with only slight
warm up. The stirring was maintained four hours and then the slurry
was allowed to settle only enough to allow the dense AB.sub.5 to
settle but keeping the fine brown gelatinous binder particles
suspended. The total solution and binder were decanted off. This
was repeated three times. The AB.sub.5 was isolated by filtration
and drying under vacuum and finally screening through -325 mesh. A
magnet was used to remove any nickel metal fines which may still be
present. The La was 25% with 0.99% oxygen and the yield was 29 g
which was 76% based on the calculated amount in the cake.
[0030] Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be understood
that such detail is solely for that purpose and that variations can
be made therein by those skilled in the art without departing from
the spirit and scope of the invention except as it may be limited
by the claims.
* * * * *