U.S. patent application number 16/218955 was filed with the patent office on 2019-04-18 for method for increasing recycled manganese content.
This patent application is currently assigned to Energizer Brands, LLC. The applicant listed for this patent is Energizer Brands, LLC. Invention is credited to Philip J. Slezak.
Application Number | 20190115601 16/218955 |
Document ID | / |
Family ID | 62567319 |
Filed Date | 2019-04-18 |
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United States Patent
Application |
20190115601 |
Kind Code |
A1 |
Slezak; Philip J. |
April 18, 2019 |
Method for Increasing Recycled Manganese Content
Abstract
Methods of recycling batteries are provided, in which reaction
conditions and elements are designed to maximize manganese recovery
while minimizing zinc and potassium impurities in the recovered
manganese. Methods of treating waste solution created by washing
the manganese, so as to remove zinc from the waste solution, are
also provided. Batteries prepared via such methods are also
provided.
Inventors: |
Slezak; Philip J.; (North
Ridgeville, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Energizer Brands, LLC |
St. Louis |
MO |
US |
|
|
Assignee: |
Energizer Brands, LLC
St. Louis
MO
|
Family ID: |
62567319 |
Appl. No.: |
16/218955 |
Filed: |
December 13, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15629177 |
Jun 21, 2017 |
10186714 |
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16218955 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 4/38 20130101; C01G
45/02 20130101; C22B 47/00 20130101; H01M 6/06 20130101; C22B 3/44
20130101; H01M 6/52 20130101; H01M 4/50 20130101; H01M 4/42
20130101; C22B 7/006 20130101 |
International
Class: |
H01M 6/52 20060101
H01M006/52; H01M 4/42 20060101 H01M004/42; C01G 45/02 20060101
C01G045/02; H01M 4/50 20060101 H01M004/50; C22B 3/44 20060101
C22B003/44; H01M 4/38 20060101 H01M004/38; C22B 47/00 20060101
C22B047/00; C22B 7/00 20060101 C22B007/00 |
Claims
1. A battery produced using a process for removing potassium from
an aqueous solution, said process comprising: a) reacting potassium
sulfate with ferric sulfate so as to form potassium jarosite,
wherein the iron:potassium ratio is no greater than about 20:1.
2. The battery of claim 1, wherein the iron:potassium ratio is no
greater than about 15:1.
3. The battery of claim 1, wherein the reaction occurs at a pH of
about 1.8 to about 2.0.
4. The battery of claim 1, wherein the aqueous solution is a
sulfuric acid solution.
5. The battery of claim 1, wherein the iron:potassium ratio is
about 11.5:1.
6. A battery produced using a process for reducing the amount of
fresh water required to recycle a plurality of batches of recovered
battery material, said process comprising the steps of: a)
contacting manganese oxide solids comprising zinc and impurities
with an acidic solution, so as to produce a waste solution
comprising impurities; b) raising the pH of the waste solution to
at least 9.0 so as to cause a portion of the impurities to
precipitate; c) removing precipitated impurities; and d) after
removing the precipitated impurities, using the waste solution to
wash additional recovered battery material; wherein the impurities
comprise zinc or potassium impurities.
7. The battery of claim 6, wherein in step b) the pH is raised to
at least 10.0.
8. The battery of claim 6, wherein in step b) the pH is raised by
adding NaOH.
9. The battery of claim 6, wherein the process further comprises
reducing the pH of the waste solution prior to step d).
10. The battery of claim 6, wherein the acidic solution is a
sulfuric acid solution.
11. (canceled)
12. A battery produced using a process for recycling batteries,
said process comprising the steps of: a) separating active
materials contained within battery cases from the battery cases,
wherein the active materials comprise fine electrode powders of
manganese oxides; b) extracting residual zinc and potassium
compounds from the fine electrode powders to obtain a purified
manganese oxide product; wherein step b) is performed using waste
solution previously generated in the course of recycling batteries;
and wherein the waste solution has been treated to remove zinc by
the addition of NaOH.
13. The battery of claim 12, wherein step b) is performed in an
aqueous solution or aqueous slurry at a pH of less than or about
1.5.
14. The battery of claim 12, wherein step a) is carried out using a
water spray to obtain a slurry of the fine electrode powders and
pieces of the battery cases.
15. The battery of claim 12, wherein the separation in step a)
comprises sieving the active materials and the battery cases
through a screen to separate the active materials from the battery
cases.
16. The battery of claim 12, wherein during step a) the active
materials are present in the form of an aqueous slurry having a pH
of greater than 8.
17. The battery of claim 12, wherein the purified manganese oxide
product from step b) is roasted at 350-400.degree. C. to remove
substantially all volatile or corrosive impurities or traces of
mercury prior to calcinating the purified manganese oxide product
at 850.degree. C. or higher.
18. The battery of claim 12, wherein the liquid to solid ratio
during step c) is between about 12:1 to about 14:1.
19. The battery of claim 12, wherein the aqueous solution or
aqueous slurry comprises sulfuric acid.
20. (canceled)
Description
BACKGROUND
[0001] Nearly 3 billion dry-cell batteries are purchased every year
in the United States. In order to reduce the number of these that
end up in landfills, efforts have been made to push both the use of
rechargeable batteries and the recycling of disposable batteries.
Recovery of battery materials via recycling can also provide cost
benefits in battery production compared to producing batteries
using all new material (Sayilgan 2009). As the demand for batteries
containing recycled materials increases, the need for more
efficient recycling processes also increases.
[0002] Processes for recycling batteries are described in U.S. Pat.
Nos. 8,728,419 and 8,911,696, both to Smith et al., as well as
Ferella et al. (2010), which are hereby incorporated by reference
in their entirety. A variety of other chemical and/or mechanical
methods for recovering metals, and particularly manganese (Mn) from
discharged batteries, are known in the art. Among the types of
batteries that comprise recoverable manganese are alkaline
batteries, in the cathode, and zinc carbon batteries, in the
interior of the battery, adjacent to the anode. The recovered
manganese can be used to make electrolytic manganese dioxide (EMD).
The recovered manganese may have impurities, including potassium
(K) and zinc (Zn), which reduces the utility of the recycling
process. For example, recycled cathode manganese recovered from
alkaline batteries inherently has high levels of potassium due to
the potassium hydroxide (KOH) electrolyte in the cell and high
levels of zinc from cross-contamination of the anode. While many
methods focus on the separation of the zinc, very little effort is
focused on removal of potassium. Current mechanical and thermal
recycling processes are ineffective at removing potassium.
Potassium negatively impacts the regenerated EMD performance,
quality, and costs. This reduces the efficiency of using the
recovered manganese to produce EMD for use in batteries comprising
recycled content. In turn, this makes it difficult to produce
batteries comprising a higher percentage of recycled manganese
("higher recycled content" or "higher content").
[0003] Consequently, a need for a more efficient process for
obtaining and purifying recycled material from discarded alkaline
or zinc carbon battery feedstock exists. In particular, a system
that reduces the amount of potassium and zinc impurities, and/or
increases the amount of recovered manganese, would be welcomed. A
method of reusing water used during the recovery process, so as to
produce less waste water in the course of recycling, would also be
welcomed.
BRIEF SUMMARY
[0004] An embodiment is a process for removing potassium from an
aqueous solution, comprising the step of: [0005] a) reacting
potassium sulfate with ferric sulfate so as to form potassium
jarosite,
[0006] wherein the iron:potassium ratio is no greater than about
20:1.
[0007] An embodiment is a process for reducing the amount of fresh
water required to recycle a plurality of batches of recovered
battery material, comprising the steps of: [0008] a) contacting
manganese oxide solids comprising zinc and impurities with an
acidic solution, so as to produce a waste solution comprising
impurities; [0009] b) raising the pH of the waste solution to at
least 9.0 so as to cause a portion of the impurities to
precipitate; [0010] c) removing precipitated impurities; and [0011]
d) after removing the precipitated impurities, using the waste
solution to wash additional recovered battery material;
[0012] wherein the impurities comprise zinc or potassium
impurities.
[0013] An embodiment is a process for recycling batteries,
comprising the steps of: [0014] a) separating active materials
contained within battery cases from the battery cases, wherein the
active materials comprise fine electrode powders of manganese
oxides; [0015] b) extracting residual zinc and potassium compounds
from the fine electrode powders to obtain a purified manganese
oxide product;
[0016] wherein step b) is performed using waste solution which has
previously been used in the course of recycling batteries; and
wherein the waste solution has been treated to remove zinc by the
addition of NaOH.
[0017] An embodiment is a battery produced using any of the above
embodiments.
BRIEF SUMMARY OF THE DRAWINGS
[0018] FIG. 1 shows the potassium impurity levels in 4% recycled
cell feed.
[0019] FIG. 2 shows potassium impurity levels in batches of
recycled electrolytic manganese dioxide (EMD) (in dotted boxes) and
non-recycled EMD (outside the dotted boxes). The X axis represents
different batches of EMD.
[0020] FIG. 3 shows weight loss results for washing recipes using a
pH of about 4 and about 1.5.
[0021] FIG. 4 shows zinc analysis for six batches of
mechanically-separated recovered cathode material.
[0022] FIG. 5 shows potassium analysis for six batches of
mechanically-separated recovered cathode material.
[0023] FIG. 6 shows manganese analysis for six batches of
mechanically-separated recovered cathode material.
[0024] FIG. 7 shows the pH of washed and dried recovered
manganese.
[0025] FIG. 8 shows a sodium analysis of one batch washed using
fresh water and five batches washed using recycled water.
[0026] FIG. 9 shows the amount of fresh and recycled water used for
the entirety of the recovery process in each of the six
batches.
[0027] FIG. 10 shows the amount of sulfuric acid and sodium
hydroxide used in the washing and water treatment for each of the
six batches.
[0028] FIG. 11 shows the effect of Fe:K ratio on final leach
potassium impurity levels for 25% recycled material.
[0029] FIG. 12 shows the impact of additional peroxide reaction
time on the final leach potassium impurity levels for 25% recycled
material, for different Fe:K ratio. Within each Fe:K ratio, from
left to right, the bars represent 10, 20 and 30 additional minutes
of soak time, respectively, added to the standard time of 30
minutes.
[0030] FIG. 13 shows the impact of using 25% recycled material on
potassium impurity levels. The left three bars represent leaching
of standard ore, while the rightmost bar represents leaching of 25%
recycled ore.
DETAILED DESCRIPTION AND DISCUSSION
[0031] Various embodiments now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments are shown. Indeed, various
embodiments may be embodied in many different forms and should not
be construed as limited to the embodiments set forth herein;
rather, these embodiments are provided so that this disclosure will
satisfy applicable legal requirements. Like numbers refer to like
elements throughout. In the following description, various
components may be identified as having specific values or
parameters, however, these items are provided as exemplary
embodiments. Indeed, the exemplary embodiments do not limit the
various aspects and concepts of the embodiments as many comparable
parameters, sizes, ranges, and/or values may be implemented. The
terms "first," "second," and the like, "primary," "exemplary,"
"secondary," and the like, do not denote any order, quantity, or
importance, but rather are used to distinguish one element from
another. Further, the terms "a," "an," and "the" do not denote a
limitation of quantity, but rather denote the presence of "at least
one" of the referenced item. For example, "an organic additive" may
refer to two or more organic additives. The word "or" is intended
to be inclusive rather than exclusive, unless context suggests
otherwise. As an example, the phrase "A employs B or C," includes
any inclusive permutation (e.g., A employs B; A employs C; or A
employs both B and C).
[0032] Each embodiment disclosed herein is contemplated as being
applicable to each of the other disclosed embodiments. All
combinations and sub-combinations of the various elements described
herein are within the scope of the embodiments.
[0033] It is understood that where a parameter range is provided,
all integers and ranges within that range, and tenths and
hundredths thereof, are also provided by the embodiments. For
example, "5-10%" includes 5%, 6%, 7%, 8%, 9%, and 10%; 5.0%, 5.1%,
5.2% . . . 9.8%, 9.9%, and 10.0%; and 5.00%, 5.01%, 5.02% . . .
9.98%, 9.99%, and 10.00%, as well as, for example, 6-9%, 7-10%,
5.1%-9.9%, and 6.01%-8.99%. As another example, ".gtoreq.90"
includes .gtoreq.91, .gtoreq.92, .gtoreq.93 . . . ; .gtoreq.90.1,
.gtoreq.90.2, .gtoreq.90.3 . . . ; and .gtoreq.90.01,
.gtoreq.90.02, .gtoreq.90.03 . . . .
[0034] As used herein, "about" in the context of a numerical value
or range means within .+-.10% of the numerical value or range
recited or claimed.
[0035] As used herein, "regular ore," "virgin ore" or "non-recycled
ore" refers to ore that has not been recovered from batteries.
[0036] As used herein, "waste solution" refers to a solution that
has already been used in at least one aspect of the battery
recycling process in order to obtain recycled manganese. The waste
solution may have impurities within, such as zinc and/or potassium.
The waste solution may be treated waste solution, meaning that it
has been altered so as to make it suitable for either re-use or
environmentally safe disposal.
[0037] As used herein, "substantially" means refers to the complete
or nearly complete extent or degree of an action, characteristic,
property, state, structure, item, or result. For example,
"Substantially all" may mean .gtoreq.90%, .gtoreq.95%, .gtoreq.99%,
.gtoreq.99.9%, or .gtoreq.99.99%.
[0038] An embodiment is a process for removing potassium from an
aqueous solution, comprising the step of: [0039] a) reacting
potassium sulfate with ferric sulfate so as to form potassium
jarosite,
[0040] wherein the iron:potassium ratio is no greater than about
20:1.
[0041] In an embodiment, the iron:potassium ratio is no greater
than about 15:1, or is about 11.5:1.
[0042] In an embodiment, the reaction occurs at a pH of about 1.8
to about 2.0.
[0043] In an embodiment, the aqueous solution is a sulfuric acid
solution.
[0044] An embodiment is a process for reducing the amount of fresh
water required to recycle a plurality of batches of recovered
battery material, comprising the steps of: [0045] a) contacting
manganese oxide solids comprising zinc and impurities with an
acidic solution, so as to produce a waste solution comprising
impurities; [0046] b) raising the pH of the waste solution to at
least 9.0 so as to cause a portion of the impurities to
precipitate; [0047] c) removing precipitated impurities; and [0048]
d) after removing the precipitated impurities, using the waste
solution to wash additional recovered battery material;
[0049] wherein the impurities comprise zinc or potassium
impurities.
[0050] In an embodiment, in step b) the pH is raised to at least
10.0. In an embodiment, in step b) the pH is raised by adding
NaOH.
[0051] In an embodiment, the pH of the waste solution is reduced
prior to step d).
[0052] In an embodiment, the acidic solution is a sulfuric acid
solution.
[0053] An embodiment is a process for recycling batteries,
comprising the steps of: [0054] a) separating active materials
contained within battery cases from the battery cases, wherein the
active materials comprise fine electrode powders of manganese
oxides; [0055] b) extracting residual zinc and potassium compounds
from the fine electrode powders to obtain a purified manganese
oxide product;
[0056] wherein step b) is performed using waste solution previously
generated in the course of recycling batteries; and wherein the
waste solution has been treated to remove zinc by the addition of
NaOH.
[0057] In an embodiment, step b) is performed in an aqueous
solution or aqueous slurry at a pH of less than or about 1.5. In an
embodiment, the pH is about 0.8.
[0058] In an embodiment, step a) is carried out using a water spray
to obtain a slurry of the fine electrode powders and pieces of the
battery cases.
[0059] In an embodiment, the separation in step a) comprises
sieving the active materials and the battery cases through a screen
to separate the active materials from the battery cases. In an
embodiment, the screen is a 20+ mesh screen.
[0060] In an embodiment, during step a) the active materials are
present in the form of an aqueous slurry having a pH of greater
than 8.
[0061] In an embodiment, the purified manganese oxide product from
step b) is roasted at 350-400.degree. C. to remove substantially
all volatile or corrosive impurities or traces of mercury prior to
calcinating the purified manganese oxide product at 850.degree. C.
or higher.
[0062] In an embodiment, the liquid to solid ratio during step c)
is between about 12:1 to about 14:1.
[0063] In an embodiment, the aqueous solution or aqueous slurry
comprises sulfuric acid.
[0064] In an embodiment, a process as described above results in
recovered manganese solids comprising <15,000 PPM Zn, <14,000
PPM Zn, <13,000 PPM Zn, <12,000 PPM Zn, <11,000 PPM Zn,
<10,000 PPM Zn, <9,000 PPM Zn, <8,000 PPM Zn, <7,000
PPM Zn, <6,000 PPM Zn, or <5,000 PPM Zn. In an embodiment, a
process as described above results in recovered manganese solids
comprising <7,000 PPM K, <6,500 PPM K, <6,000 PPM K,
<5,500 PPM K, <5,000 PPM K, <4,500 PPM K, <4,000 PPM K,
<3,500 PPM K, or <3,000 PPM K. In an embodiment, a process as
described above results in recovered manganese solids comprising
>46% Mn, >47% Mn, >48% Mn, >49% Mn, >50% Mn, >51%
Mn, >52% Mn, >53% Mn, or >54% Mn, by weight.
[0065] An embodiment is a battery produced using any of the above
embodiments. In an embodiment, the battery is an alkaline battery.
In another embodiment, the battery is a carbon zinc battery. In an
embodiment, the battery comprises manganese, wherein greater than
about 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%,
17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%,
30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%,
43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%,
56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%,
69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%,
82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%,
95%, 96%, 97%, 98%, 99%, or 99.9% of the manganese, by weight
percent, is recovered from recycled batteries. In an embodiment,
about 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%,
17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%,
30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%,
43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%,
56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%,
69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%,
82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%,
95%, 96%, 97%, 98%, 99%, 99.9%, or 100% of the manganese, by weight
percent, is recovered from recycled batteries.
[0066] One way of separating the cathode from the battery is via a
mechanical process, for example, as described in U.S. Pat. No.
9,620,790, which is incorporated herein by reference in its
entirety. In this process, for alkaline batteries, the battery is
cut opened and the anode is removed. The cathode is then crushed
and the can is removed via mechanical separation. For zinc carbon
batteries, the exterior part of the battery would be removed, and
the inside of the battery, containing manganese, would be kept for
further processing. A second way of separating the cathode from the
battery is via a hydrometallurgical process. Here, the batteries
are crushed and shredded, the large can pieces and paper are
removed, and the material is then hydrometallurgically cleaned to
remove most of the zinc and potassium. Different types of
batteries, such as alkaline batteries and zinc carbon batteries,
may be shredded together.
[0067] As mentioned, recovered manganese has potassium and zinc
impurities which reduce its quality. For higher recycled content
EMD materials, these levels should be less than 15,000 PPM Zn and
less than 7,000 PPM K. Typical non-recycled ore has approximately
5,000-8,000 PPM K, and <100 PPM Zn. Further, the manganese
content of the recovered material should be at least 48%. Typical
non-recycled (i.e. virgin) ore contains approximately 48-50%
manganese.
[0068] In a first step of a hydrometallurgical process used to
separate the cathode from the remainder of the battery, the
batteries may be fed through a crusher or shredder to open up the
batteries and thereby liberate the electrode powders contained
within. In one embodiment, a hammer mill with water spray is
employed, although alternatively this step may be run dry. The pH
optionally may be greater than 8 following this step, as a neutral
or higher pH may help protect the equipment from corrosion. To
raise the pH greater than 8, an alkali hydroxide, such as sodium
hydroxide (NaOH) or potassium hydroxide (KOH) may be added.
However, it usually will not be necessary to add an alkali
hydroxide for recycling alkaline batteries alone, because of the
inherent alkalinity of alkaline batteries.
[0069] The crushed batteries, which are typically in the form of an
aqueous slurry, may then be deposited onto a shaker table or
surface providing size separation (screening action). The coarser
material containing almost all of the steel from the battery cases,
the brass pins, separator materials and coarser case materials
remain on the shaker table or screening device. The shaker table or
screening device may have 1/4'' openings, for example (although the
shaker table may have openings of any of a variety of sizes). The
finer electrode materials containing substantially all of the
manganese oxides, carbon, zinc hydroxides, other zinc compounds,
and any unreacted powdered zinc metal can be passed through a
screen (e.g., a 20+ mesh screen) to produce a basic slurry
(typically having a pH greater than 9). Optionally, this basic
slurry may be passed through a magnetic separator to remove any
small pieces of steel which may still be present. The slurry is
next combined with sulfuric acid. The coarser material (for
example, material captured by the 20+ mesh screen) which is
separated from the initial crushed batteries may be dried and
passed through a magnetic separator to recover clean steel
particles, which can then be recycled (to steel mills, for
example).
[0070] Alternatively, in a mechanical separation process, for
alkaline batteries, a battery (or multiple batteries
simultaneously) may have its ends cut off, such as by a saw, a
water jet, and/or the like, and then have the anode basket pushed
out, such as by a finger with air. The remaining material, the can
and the cathode material, is shredded, for example, by a shredder.
The steel is removed from this shredded material via magnetic
separation. The remaining material is the cathode (manganese)
material. For zinc carbon batteries, the interior of the batteries
would contain the manganese oxide solids, so the interior of the
battery would be retained. To wash the manganese oxide solid
material, it may then be slurried in water and combined with
sulfuric acid. Alternatively, an aqueous sulfuric acid solution may
be combined directly with the recovered solids.
[0071] In either case, the sulfuric acid serves to extract zinc and
potassium remaining in the manganese oxide solids, thereby
producing an acid-extracted manganese oxide product, in a washing
step. The manganese oxide solids may contain manganese dioxide
(MnO.sub.2) and other discharged products, such as manganese (III)
oxide (Mn.sub.2O.sub.3), manganese (II) hydroxide (Mn(OH).sub.2),
manganese (II,III) oxide (Mn.sub.3O.sub.4), or zinc manganate
(ZnMn.sub.2O.sub.4). The goal is to remove zinc and potassium while
minimizing manganese dissolution. The ultimate goal is to dissolve
the zinc and potassium while leaving the manganese as a solid.
Typically, an amount of sulfuric acid is used which is sufficient
to achieve a pH below 3 in the aqueous slurry of manganese oxide
solids.
[0072] In a preferred embodiment, a pH less than or about 1.5 is
achieved. In another preferred embodiment, a pH less than or about
0.8 is achieved. In an embodiment, the liquid to solid ratio is
about 5:1 to 15:1. In a preferred embodiment, the liquid to solid
ratio is about 5:1 to 7:1. In a more preferred embodiment, the
liquid to solid ratio is about 5.6:1. In a preferred embodiment,
the liquid to solid ratio is about 12:1 to 14:1. In a more
preferred embodiment, the liquid to solid ratio is about 13:1. The
mixture of manganese oxide solids, sulfuric acid and water may be
agitated or mixed by stirring, for example. The manganese oxide
solids may be contacted with the sulfuric acid for a time and at a
temperature effective to achieve a desired reduction in the zinc
and potassium content of the manganese oxide solids. For example,
such contacting may be carried out for about 30 minutes to about 4
hours at a temperature of from about room temperature (or
25.degree. C.) to about 70.degree. C. In an embodiment, water used
in this process is reused, treated water used in previous battery
recycling.
[0073] For mechanically separated material, in a preferred
embodiment, a liquid to solid ratio of approximately 13:1 is used,
at a pH of 1.5, for about 30 minutes, at approximately room
temperature.
[0074] For hydrometallurgically separated material, in a preferred
embodiment, a liquid to solid ratio of about 5.6:1 is used, at a pH
of about 0.8, for at least about 4 hours at about 70.degree. C. In
another embodiment, a liquid to solid ratio of about 13:1 is used,
at a pH of about 1.4 to about 1.5, for between 30 minutes and 4
hours at about 70.degree. C.
[0075] The further purified manganese oxide solids (acid-extracted
manganese oxide product) may be separated from the sulfuric acid
solution by any suitable method, such as filtration. If filtration
is used, the resulting filter cake may be washed. The pH of the
acidic extract obtained as a result of the treatment with sulfuric
acid may be adjusted, through the addition of a base such as an
alkali hydroxide, to a pH of about 9 to about 10 to precipitate the
extracted zinc as well as the extracted manganese that may be
present in the acidic extract. This washing step uses a significant
amount of water, which can be treated as discussed below so as to
reduce the amount of waste water produced.
[0076] The separated manganese oxide solids separated from the
sulfuric acid solution may thereafter be furnaced under a low
oxygen atmosphere at a temperature of 850.degree. C. or greater to
convert MnO.sub.2 to manganese (II) oxide (MnO). For example, the
low oxygen atmosphere may be an inert atmosphere, e.g., a nitrogen
atmosphere. In one embodiment, the low oxygen atmosphere used
contains less than 5% O.sub.2 by volume. The furnacing temperature
may be about 900.degree. C., for example. Prior to furnacing under
the low oxygen atmosphere, the acid-extracted manganese oxide
product may be subjected to a distinct initial step wherein it is
first roasted at 350-400.degree. C. prior to heating to the
furnacing temperature (850.degree. C. or greater). This initial
roasting step may be carried out under conditions effective to
remove any volatile or corrosive impurities or traces of mercury.
The product obtained by furnacing, a calcined ore, may be cooled
under an inert atmosphere to protect it from re-oxidation. This
product may be subsequently packaged and shipped to another
location for subsequent stages in the recycling process.
[0077] The manganese oxide solids prior to furnacing may contain
some graphite carbon derived from the batteries; this carbon aids
in the conversion of MnO.sub.2 to MnO.
[0078] As an alternative method of converting MnO.sub.2 to MnO, the
manganese may be reduced using iron pyrite (FeS.sub.2). As another
alternative method, the MnO.sub.2 may be chemically converted to
manganese (II) carbonate (MnCO.sub.3). In this process, a solution
having zinc and manganese is treated with ammonium carbonate in
ammonia. The carbonate preferentially reacts with the manganese to
form manganese (II) carbonate. The zinc remains in solution.
Manganese (II) carbonate decomposes at elevated temperature (at
least about 200.degree. C.) to produce manganese (II) oxide, with a
release of carbon dioxide. Alternatively, the manganese carbonate
can be used directly to generate EMD, along with carbon dioxide,
without first being decomposed to manganese (II) oxide.
[0079] The recovered, optionally washed MnO then undergoes a
leaching process. The steps of this process may be seen in Table 1,
below. The reactions are generally performed in the temperature
range of 92-98.degree. C. "G/L" means grams per liter.
TABLE-US-00001 TABLE 1 Leaching reactions (with Hydrogen shuttle)
Reaction Steps/Conditions Reaction 1: Calcined ore 30+ G/L 38+ G/L
Leaching of MnO + H.sub.2SO.sub.4 .fwdarw. MnSO.sub.4 + H.sub.2O
manganese Reaction 2: Ferrous oxide (+2) pH < 1.8 Ferrous
sulfate (+2) Dissolution of FeO + H.sub.2SO.sub.4 .fwdarw.
FeSO.sub.4 + H.sub.2O ferrous oxide Reaction 3: Ferrous sulfate C4
ore pH <1.8 Ferric sulfate Conversion of 2FeSO.sub.4 + MnO.sub.2
+ 2H.sub.2SO.sub.4 .fwdarw. Fe.sub.2(SO.sub.4).sub.3 + MnSO.sub.4 +
ferrous to ferric 2H.sub.2O Reaction 4: Hydrogen peroxide pH 1.8
Ferric iron Conversion of 2Fe.sup.+2 + H.sub.2O.sub.2 + 2H.sup.+
.fwdarw. 2Fe.sup.+3 + 2H.sub.2O remaining 2FeSO.sub.4 +
H.sub.2O.sub.2 + H.sub.2SO.sub.4 .fwdarw. Fe.sub.2(SO.sub.4).sub.3
+ 2H.sub.2O ferrous to ferric MnO.sub.2 + H.sub.2O.sub.2 + 2H.sup.+
.fwdarw. Mn.sup.+2 + H.sub.2O + O.sub.2 and dissolve surface
MnO.sub.2 Reaction 5: Ferric sulfate pH 1.8-2.0 Potassium jarosite
Jarosite K.sub.2SO.sub.4 + 3Fe2(SO.sub.4).sub.3 + 12H.sub.2O
.fwdarw. 2KFe.sub.3(SO.sub.4).sub.2(OH).sub.6 + reaction
6H.sub.2SO.sub.4 (potassium removal) Reaction 6: Calcined ore pH 3
<< 55 G/L Leaching of MnO + H.sub.2SO.sub.4 .fwdarw.
MnSO.sub.4 + H.sub.2O manganese Reaction 7: Hydrogen peroxide pH 3
Ferric iron Conversion of 2Fe.sup.+2 + H.sub.2O.sub.2 + 2H.sup.+
.fwdarw. 2Fe.sup.+3 + 2H.sub.2O remaining 2FeSO.sub.4 +
H.sub.2O.sub.2 + H.sub.2SO.sub.4 .fwdarw. Fe.sub.2(SO.sub.4).sub.3
+ 2H.sub.2O ferrous to ferric MnO.sub.2 + H.sub.2O.sub.2 + 2H.sup.+
.fwdarw. Mn.sup.+2 + H.sub.2O + O.sub.2 Reaction 8: Ferric iron pH
>3.6 Ferric hydroxide Precipitation of 2Fe.sup.+3 + 6H.sub.2O
.fwdarw. 2Fe(OH).sub.3 + 6H.sup.+ ferric Reaction 9: Calcined ore
pH > 4.1 55 G/L Leaching of MnO + H.sub.2SO.sub.4 .fwdarw.
MnSO.sub.4 + H.sub.2O manganese
[0080] Controlling the iron:potassium (Fe:K) ratio in Reaction 5
(the jarosite reaction) is important for maximizing potassium
removal. In an embodiment, the Fe:K ratio is no greater than about
or about 20:1. In a preferred embodiment, the Fe:K ratio is no
greater than about or about 15:1. In a more preferred embodiment,
the Fe:K ratio is no greater than about or about 11.5. A higher
Fe:K ratio may be used, but low-potassium ore or a caustic solution
(i.e., lime, NaOH . . . ) will need to be used to raise the final
pH. Further, the hydrogen peroxide (H.sub.2O.sub.2) steps
(Reactions 4 and 7) should take at least 15 and 30 minutes,
respectively, but may each be extended in order to allow more
potassium to be dissolved. When the Fe:K ratio is maintained at
11.5, added time for the hydrogen peroxide steps improves the
removal of potassium, but added time may not be necessary, given
that the standard times of 15 and 30 minutes usually results in
sufficient removal of potassium. FIG. 12 shows the effects of
additional soak time during Reaction 7 on final potassium levels.
Further, when there is excess ferric iron in solution, Reaction 8
reduces the pH of the solution so as to cause the process to go
back to Reaction 5.
[0081] Following the leaching process, sulfiding is then performed
in order to remove heavy metals, including zinc, copper (Cu),
cobalt (Co), nickel (Ni), molybdenum (Mo), and mercury (Hg). The
reactions are shown below, in Table 2. The reactions are generally
performed in the temperature range of 70-80.degree. C.
TABLE-US-00002 TABLE 2 Sulfiding reactions for heavy metal removal
pH 3.8-4.2 Hydrogen Sulfide Gas 2NaSH + H.sub.2SO.sub.4 .fwdarw.
2H.sub.2S .uparw. + Na.sub.2SO.sub.4 Hydrogen Sulfide Insoluble
Metal Sulfides H.sub.2S + M.sup.++ .fwdarw. MS .dwnarw. + 2H.sup.+
(where M.sup.++ = Zn, Cu, Co, Ni, Mo, Hg)
[0082] Sodium hydrosulfide (NaSH or NaHS) is added in the sulfiding
process. In the presence of residual acid (pH=4) remaining from the
leaching process, NaHS will convert to hydrogen sulfide (H.sub.2S)
gas (.uparw.). The gas reacts with heavy metals to produce metal
sulfides, which precipitate out of solution (.dwnarw.) for easy
removal. In this process, there is a limit on how much and how
quickly NaHS can be safely added to the solution. If an excess
amount of NaHS is added, or is added at an accelerated rate,
H.sub.2S will release from liquid prior to reacting (when
pH<4.6), which will cause excessive gassing. As H.sub.2S is
poisonous, corrosive, and flammable, it is desirable to avoid such
an occurrence.
[0083] Following the sulfiding process, the MnSO.sub.4 may be used
to prepare EMD by any method known in the art.
[0084] In past efforts at preparing cathodes comprising 4% recycled
manganese, the impurity level of potassium in cell feed averaged 20
PPM (FIG. 1), more than twice the standard amount in non-recycled
material. In order to get the potassium impurity level down to 20
PPM, significant amounts of ferric sulfate were added in order to
precipitate out the potassium. The final EMD product for the
recycled material had potassium levels double (350 PPM) what is
typically observed with non-recycled EMD production (175 PPM) (FIG.
2, showing potassium levels in EMD produced from recycled (in the
dotted boxes) and non-recycled (outside the dotted boxes)
manufacturing methods). For zinc, three times the normal amount of
NaHS was required to remove this impurity.
[0085] Because higher recycled content manganese (i.e. >4%
recycled) contains so much more zinc than non-recycled zinc, the
sulfiding step requires more NaHS (more than six times as much,
currently). While slowing down the NaHS feed rate can reduce the
H.sub.2S release, these elevated concentrations create an increased
opportunity for H.sub.2S gassing. By reducing the amount of zinc
remaining in the recycled content post-leaching, the risk of
gassing is reduced, as is the amount (and, thereby, cost) of added
NaHS required for the process. Further, early assessment of
producing a higher recycled content battery predicts that potassium
levels would increase to over 500 PPM, an unsuitably high
level.
[0086] The recycling process requires a significant amount of
water, which will ultimately comprise impurities (such as zinc,
potassium, and sodium compounds, including zinc oxide, zinc
carbonate, potassium carbonate, and sodium carbonate) removed from
the manganese. Each batch of approximately 2,500 lbs of material
used 4,200 gallons of fresh water from start to finish. As
mentioned above, a significant portion of this water is used in the
washing step. Reusing this water is not ideal, as the resulting
washed manganese could contain too high of a zinc concentration to
be suitable for use as a battery. To avoid having to dispose of the
water as waste, the zinc is removed. The pH of the water is raised
by adding NaOH, preferably to a pH of at least about 9.0, more
preferably to a pH of at least about 10.0, and even more preferably
to a pH of at least about 10.1, and the zinc will drop out, as zinc
carbonate (ZnCO.sub.3) or zinc oxide (ZnO). The water, with the
zinc removed, is then suitable for reuse.
EXAMPLES
Example 1--pH in Washing Step
[0087] Trials were conducted to hydrometallurgically clean
recovered, mechanically separated material. In these trials, a
sulfuric acid solution was used to wash the material. Both zinc and
manganese will dissolve in low pH (high acid concentration)
solutions. These evaluations looked at the acid concentration level
(pH) on its effectiveness in removing potassium, zinc, and
manganese. The goal was to achieve recipes that would remove
potassium only and another to remove potassium and zinc while
minimizing manganese dissolution. The ultimate goal is to dissolve
the zinc and potassium while leaving the manganese behind as a
solid. These methods were tested on six batches of recovered
cathode material (Ore 338, Ore 339, Ore 340, Ore 341, Ore 342, and
Ore 343) obtained from mechanically (M) separated batteries, and
compared to the cathode material recovered from typically-washed
hydrometallurgically (HM) separated batteries (Typical HM wash) and
mechanically-separated, unwashed batteries (Typical M). 1,500
gallons of water was added to a wash tank, and 2,500 lbs of
recycled material was sent through the hammer mill and added on top
of the water, while the tank is mixing. Once added, the pH was
adjusted with sulfuric acid and mixed for 30 minutes at room
temperature, using a liquid to solid ratio of 13:1. The Typical HM
wash material was mixed for 240 minutes at a temperature of
70.degree. C., using a liquid to solid ratio of 5.6:1. The results
are summarized in Table 3, below:
TABLE-US-00003 TABLE 3 Summary of results of washes at pH 1.5 and 4
Typical Typical Typical New process for M wash Ore C4 HM wash M pH
4 pH 1.5 Target Zn (PPM) <100 29,000 70,000-100,000
70,000-100,000 4,200 <15,000 K (PPM) 5000-7000 9,000 43,000
8,000 3,200 <7,000 Mn (%) 48-50 46 46.5 51 51.5 >48
[0088] Based on the factorial design experiments, it was found that
a sulfuric acid solution with pH of 4 will be effective in removing
only potassium. To remove zinc and potassium while minimizing the
manganese losses, a pH of 1.5 was found ideal. At this pH level, up
to 95% of the zinc and 92% of the potassium can effectively be
removed, with relatively low dissolution of manganese. The
remaining potassium is tied up in the manganese structure and can
only be removed when the manganese is dissolved. Weight loss
results, showing the utility of recipes having a pH of about 1.5
and a pH of about 4, may be seen in FIG. 3.
[0089] Since removal of both potassium and zinc was needed, the
lower pH (1.5) was selected for further evaluations. As can be
seen, the impact of this post washing (i.e. washing post-mechanical
separation) on the mechanically separated material resulted in this
material having lower potassium and higher manganese content as
compared to regular non-recycled ore. The optimal cleaning
conditions found to achieve this while minimizing added costs from
washing (liquid and washing time) was to use a liquid to solid
ratio of 13:1 with a minimum of a 30 minute wash at a pH of
1.5.
[0090] FIG. 4 shows the zinc analyses for the starting materials
labeled Ore 338 to Ore 343. These are unwashed batches of
mechanically-separated recovered cathode material used for each
wash. Mn Cake-338 to Mn Cake-343 represent the analyses of zinc in
the manganese product (reported as dry basis) in the wet product
cake prior to drying. The Dried 338 & 339 (comprising all of
batch 338 and half of batch 339) and Dried 339 & 340
(comprising all of batch 340 and half of batch 339) represent the
final product. These are two final product batches where each dried
product represents 1.5 wet cakes samples to produce the final
product. As is evident in the figure, the zinc levels remained flat
for each of the washed cakes and in the final product, confirming
the process is stabilized. Both are approximately 4,000 PPM. This
is significantly lower than the target of <15,000 PPM.
[0091] FIG. 5 shows the potassium analyses for the same materials
as in FIG. 4. As is evident in the figure, the potassium levels
also remained flat for each of the washed and in the final product
confirming the process is stabilized. Both are approximately 3,000
PPM, which is well below even current virgin ore used, as well as
the target of <7,000 PPM. As a result, the impact of potassium
should be significantly improved for recycled and non-recycled
batteries if this material is used.
[0092] FIG. 6 shows the manganese analyses for the same materials
as in FIG. 4. As is evident in the figure, the manganese levels
also remained flat for each of the washed batches and in the final
product confirming the process is stabilized. Both are
approximately 51.5%, which is higher than currently used virgin
ore, which has a 46 to 50% manganese content, and is also higher
than the target of >48% manganese content. As a result, the
manganese usage should be significantly improved for recycled and
non-recycled batteries if this material is used.
[0093] FIG. 7 is the pH of the two dried products (one with half of
batch 339 and all of batch 338, and another with half of batch 339
and all of batch 340). Both had a pH greater than 4, which is
beneficial for the calcining process. At these current higher
levels, there is no risk of corrosion, and the material is not
considered hazardous. Further production campaigns produced after
this effort continue to have a pH above 4 (data not shown).
Example 2--Water Treatment and Re-Use
[0094] As discussed above, the washing process uses a significant
amount of water. Each batch (containing approximately 2,500 lbs of
recycled cathode material) required 4,200 gallons of liquid, which
would need to be treated as waste water and subsequently disposed
of. Reusing the acid solution, without treatment, was attempted. In
a first trial of reusing the water, both potassium and zinc were
removed in an adequate amount. However, when the acid solution was
re-used in another batch, the zinc level increased from 4,200 PPM
to greater than 30,000 PPM. While better than unwashed material,
this was unsuitable for efficient manufacturing processes.
[0095] A new hydrometallurgical process was designed to clean the
manganese and then raise the pH of the liquid with sodium hydroxide
(NaOH) to a pH of 10, which drops the zinc out of solution. The
liquid, without the zinc, may then be re-used for the washing
process, or returned to tanks for later re-use.
[0096] The first batch described above (Ore 338) was washed with
fresh liquid, and then each of the five subsequent batches (Ore
339, Ore 340, Ore 341, Ore 342, and Ore 343) were washed with
liquid which had been treated to remove zinc. The results showed
that the treated liquid can be used at least 5 times. There is no
indication that this is a limit for the total number of times that
the liquid can be treated and re-used.
[0097] FIG. 8 shows the sodium (Na) analyses for the Mn Cake-338 to
Mn Cake-343 (reported as dry basis) in the wet product cake prior
to drying, and the average for all six batches. As is evident in
the figure, the sodium levels also remained relatively flat for
each of the washed products confirming the process is stabilized.
This shows that, even though sodium is used to treat the water,
there was no increase in sodium levels (i.e. buildup) over
time.
[0098] The material washed with only fresh water (Ore 338) was
compared to all of the washed samples. As the sodium concentration
increased, it dropped out in the zinc product, leaving the sodium
levels in the manganese product stable.
[0099] FIG. 9 is the amount of water used for each of the batches.
Batch 338 used only fresh water (H.sub.2O), while the subsequent
batches each used 1,500 gallons of the treated water (H.sub.2O--R)
in the washing step. The remaining fresh water is used in the
breaking, shredding and sieving of batteries in the process of
obtaining the recycled material. In an embodiment, water obtained
from the drying of the product is used in these processes. In
another embodiment, more than 1,500 gallons of the water is treated
and reused. In another embodiment, all of the water is treated and
re-used.
[0100] FIG. 10 shows the amount of sulfuric acid used to wash the
manganese product (first bar in each column), the amount of NaOH
used to treat the water to remove the zinc (second bar), and
additional sulfuric acid used, if necessary, if the target pH was
overshot in the treatment (third bar). Overall, the data shows that
when using fresh water only, 55 gallons of 95% sulfuric acid is
needed to wash the material at a pH of 1.5 and 80 gallons of 50%
NaOH is needed to treat the water to remove the zinc at a pH=10.
During the use of recycling of water, 67 gallons of acid and 100
gallons of caustic were needed. These recipes were confirmed during
the full scale production of washing this material.
Example 3--Leach Optimization of Fe:K Ratio
[0101] As discussed above, potassium is also removed during the
leaching step, following the washing step. Efforts to optimize
potassium removal via the jarosite reaction were examined.
[0102] Leaching trials were conducted on 25% recycled material with
various Fe:K ratios (11.5, 15, and 20) to determine what ratio
minimizes the potassium in the final cell feed solution. To conduct
this evaluation, the hydrometallurgically recycled material was
selected as its impurities will be higher than the improved washed
mechanically separated material. Therefore, the material represents
the worst case scenario expected during production. To achieve the
various levels of Fe:K, ferric sulfate was added.
[0103] The results, seen in FIG. 11, confirmed that the lowest
overall potassium levels were achieved while using the 11.5 Fe:K
ratio. Prior to this effort, previous work has shown that 11.5 is
the minimum amount required to drive the jarosite reaction to
remove potassium. This current work confirms that increasing the
ratio above this will only increase the potassium level of the
final solution. This is a result of the potassium that is included
in the final ore addition to raise the pH. With higher Fe:K ratios,
more ore is required to drive the pH above 3.8, the minimum level.
More ore containing higher potassium levels only led to more
potassium being dissolved into solution at the end of the leach
process.
Example 4--Leach Optimization of Peroxide Step
[0104] Another variable that was considered was the impact of
holding the leach longer during the H.sub.2O.sub.2 (peroxide) step
to allow more potassium to be dissolved and react with the ferric.
FIG. 12 summarizes the findings of increasing the time during the
H.sub.2O.sub.2 step by 10, 20, and 30 minutes, using different Fe:K
ratio. As expected, the longer times will aid in removing potassium
regardless of the Fe:K ratio use.
[0105] However, as discussed, maintaining the Fe:K ratio at 11.5 is
critical to avoid excess potassium needing to be added in the last
ore addition. At this level, the added time does continue to
improve removal of potassium; however, the current process is
already within the range normally observed in non-recycled
manganese production. Considering added time leads to more
constraints for the remaining process and added costs, it is not
recommended unless absolutely necessary to force potassium levels
lower.
Example 5--Leaching
[0106] Given the determinations made in the previous Examples, a
small-scale capping run experiment was completed with 25% washed,
mechanically-separated material. The results of this trial
confirmed the current recipe with a potassium level of 1 PPM is
achieved with this material (FIG. 13), which was lower than trials
completing virgin ore. Moreover, as a result of the higher
manganese content from washing the material, the amount of calcined
ore (i.e. MnO) that must be added during the leach, in order to
adjust the pH, is reduced. Table 4, below, compares the amount of
ore added for the leaching of virgin (standard) ore compared to the
leaching of the washed, 25% recycled material blend.
TABLE-US-00004 TABLE 4 Final recipe, standard ore vs. 25% washed
and recycled material Standard Washed 25% blend Step Ore Added (g)
pH Start-End Ore Added (g) pH Start-End Initial 24 0.572-1.401 24
0.572-1.443 pH 1.6 5 1.401-1.660 4 1.443-1.701 Jarosite 3
1.981-2.072 2 1.989-2.051 H.sub.2O.sub.2 4 2.675-3.311 4
2.715-3.210 Final 6.5 3.379-4.337 3 3.225-4.391 Total 42.5 37 % of
100% 87% standard ore used
[0107] The trial confirmed that 13% less ore was required when
using the cleaner, higher manganese content recycled material. This
should correlate to an increase in manganese efficiency and a
decrease in the solids removed during the leach process as compared
to virgin ore will be expected.
[0108] Many modifications and other embodiments will come to mind
to one skilled in the art to which these embodiments pertain having
the benefit of the teachings presented in the foregoing
descriptions and the associated drawings. Therefore, it is to be
understood that the embodiments are not to be limited to the
specific embodiments disclosed and that modifications and other
embodiments are intended to be included within the scope of the
appended claims and list of embodiments disclosed herein. Although
specific terms are employed herein, they are used in a generic and
descriptive sense only and not for purposes of limitation. For the
embodiments described in this application, each embodiment
disclosed herein is contemplated as being applicable to each of the
other disclosed embodiments.
LIST OF REFERENCES CITED
[0109] U.S. Pat. No. 8,728,419 to Smith et al., issued May 20, 2014
[0110] U.S. Pat. No. 8,911,696 to Smith et al., issued Dec. 16,
2014 [0111] U.S. Pat. No. 9,620,790 to Deighton, issued Apr. 11,
2017 [0112] Ferella F. et al., "Extraction of Zinc and Manganese
from Alkaline and Zinc-Carbon Spent Batteries by Citric-Sulphuric
Acid Solution," Intl. J. Chem. Engineering, Article ID 659434
(2010) [0113] Sayilgan E. et al., "A review of technologies for the
recovery of metals from spent alkaline and zinc-carbon batteries,"
Hydrometallurgy, 97:158-166 (2009)
* * * * *