JP5847742B2 - Waste cathode material and method for recovering metal from waste battery - Google Patents

Description

  The present invention relates to a waste cathode material and a method for recovering metal from a waste battery. In particular, the present invention relates to a waste cathode material of a lithium ion battery and a method for recovering a metal constituting the cathode material from the waste battery.

  Lithium ion batteries are rapidly expanding their applications for hybrid vehicles. Furthermore, the production volume of large batteries is expected to increase rapidly as the capacity of the unit increases. Further, with the growing demand for lithium ion batteries, establishment of a method for recovering valuable metals from lithium ion batteries is required.

  A lithium ion battery mainly comprises a positive electrode, a negative electrode, a separator, and a casing. The positive electrode is made of a positive electrode active material containing manganese, cobalt, nickel, lithium, etc. on a current collector such as an aluminum foil. It has a structure in which it is bonded via a binder. A copper foil is used as a current collector for the negative electrode. The casing is made of iron or aluminum. In addition, chromium, carbon, phosphorus, etc. are often detected from waste batteries.

  As a recycling method for lithium ion batteries, acid leaching is performed using raw materials after incineration, crushing and sorting used lithium ion batteries, and then each metal is extracted and separated by solvent extraction from the obtained leachate. A method has been proposed.

For example, JP 2010-180439 A (Patent Document 1) describes a method of removing iron and aluminum by neutralization treatment. Specifically, it is a method for recovering nickel from a sulfuric acid aqueous solution containing nickel and cobalt and iron, aluminum, manganese and other impurity elements, and includes the following steps (1) to (5): A method for recovering nickel from an acidic sulfuric acid aqueous solution is disclosed.
Process (1): Precipitation containing iron and aluminum produced by adding calcium carbonate to the acidic aqueous sulfuric acid solution while blowing a mixed gas composed of sulfurous acid gas and air or oxygen gas, and subjecting to oxidation neutralization treatment. Product (a) is removed.
Step (2): Calcium hydroxide is added to the post-oxidation neutralized solution obtained in the above step (1) and subjected to neutralization to separate and recover the mixed hydroxide containing nickel and cobalt. .
Step (3): The mixed hydroxide obtained in the step (2) is subjected to a dissolution treatment in a sulfuric acid solution having a concentration of 50% by mass or more, and a precipitate (b) containing manganese and gypsum produced. Is removed to obtain a nickel and cobalt concentrate.
Step (4): The concentrated solution obtained in the step (3) is subjected to solvent extraction using a phosphoric acid ester-based acidic extractant, and an extraction residual solution containing nickel and a back extract containing cobalt are obtained. obtain.
Step (5): A neutralizing agent is added to the extraction residual liquid obtained in the step (4) and subjected to neutralization treatment, and the produced nickel hydroxide is separated and recovered.

JP 2010-180439 A

  The method described in Patent Document 1 is a method in which nickel, cobalt, and manganese are separated and recovered from an acidic sulfuric acid aqueous solution that contains nickel, cobalt, and iron, aluminum, manganese, and other impurity elements. However, since nickel, cobalt, and manganese are used in combination as constituent elements of the positive electrode active material of the lithium ion battery, there is little need to separate them. It is considered sufficient to be able to separate elements that are not used in the positive electrode active material. Also, if these are separated and recovered, the recovery process becomes more complicated and the recovery cost becomes higher.

  Therefore, an object of the present invention is to provide a simple and economical metal recovery method that is useful for regenerating a positive electrode material from a waste battery, a waste positive electrode material, or a mixture thereof.

In one aspect, the present invention provides:
A method for recovering a metal group A from a waste battery, a waste cathode material or a mixture thereof containing a metal group A consisting of at least two kinds of Co, Ni and Mn and impurities, the waste battery, a waste cathode material, or these Recovering metal group A as a mixture of metal salts after removing impurities from the mixture.

  In one embodiment of the method according to the invention, the metal salt is a solid.

In another embodiment of the method according to the present invention, an impurity element group C consisting of at least one of Fe, Cr, Al and Cu is included as an impurity, and the following steps (1), (3), (4) , (6) and (7) are performed according to the following conditions.
Step (1): A step of leaching sulfuric acid from a waste battery, a waste cathode material or a mixture thereof to obtain a leachate,
Step (3): When at least one of Fe and Cr is contained in the impurity element group C, a basic neutralizing agent is added to the leachate, and the pH of the leachate is adjusted to a range of 5 to 6 in the metal. A step of precipitating the sum,
Step (4): When Al and Cu are contained in the impurity element group C, a step of separating Cu and Al from the leachate by solvent extraction to the solvent side,
Step (6): A step of separating impurities from the leachate by performing solid-liquid separation after performing at least the last step among steps (3) and (4).
Step (7): A step of recovering the metal group A as a mixture of metal salts from the separated liquid obtained in the step (6).

In still another embodiment of the method according to the present invention, the impurity element group B consisting of at least one of C, P and F is included as an impurity, and the following steps (1), (2), (5), (6) and (7) are performed according to the following conditions.
Step (1): A step of leaching sulfuric acid from a waste battery, a waste cathode material or a mixture thereof to obtain a leachate,
Step (2): if it contains P in an impurity element group B, step to precipitate the iron phosphate by addition of Fe ³⁺ source leachate,
Step (5): When F is contained in the impurity element group B, a step of adding calcium compound to the leachate and precipitating calcium fluoride by adjusting the pH to a range of 5 to 8,
Step (6): A step of separating impurities from the leachate by performing solid-liquid separation after performing at least the last step among steps (2) and (5),
Step (7): A step of recovering the metal group A as a mixture of metal salts from the separated liquid obtained in the step (6).

In still another embodiment of the method according to the present invention, as impurities, an impurity element group B consisting of at least one of C, P and F and an impurity element group C consisting of at least one of Fe, Cr, Al and Cu are used as impurities. And the method according to claim 1 or 2, comprising carrying out steps (1) to (7) according to the following conditions.
Step (1): A step of leaching sulfuric acid from a waste battery, a waste cathode material or a mixture thereof to obtain a leachate,
Step (2): if it contains P in an impurity element group B, step to precipitate the iron phosphate by addition of Fe ³⁺ source leachate,
Step (3): When at least one of Fe and Cr is contained in the impurity element group C, a basic neutralizing agent is added, and the pH of the leachate is adjusted to a range of 5 to 6 to neutralize the metal. Precipitating,
Step (4): When Al and Cu are contained in the impurity element group B, a step of separating Cu and Al from the leachate by solvent extraction to the solvent side,
Step (5): When F is contained in the impurity element group B, a step of adding calcium compound to the leachate and precipitating calcium fluoride by adjusting the pH to a range of 5 to 8,
Step (6): A step of separating the impurity element group B from the leachate by performing solid-liquid separation after performing at least the last step among the steps (2) to (5),
Step (7): A step of recovering the metal group A as a mixture of metal salts from the separated liquid obtained in the step (6).

  In a further embodiment of the method according to the invention, the metal salt is a hydroxide, sulfate, carbonate or nitrate.

  In yet another embodiment of the method according to the present invention, in step (7), a basic neutralizing agent is added to the separation liquid obtained in step (6), and the pH of the leachate is in the range of 8-11. In which the mixed hydroxide of metal group A is precipitated and the mixed hydroxide of metal group A is recovered on the solid side by solid-liquid separation, or sulfuric acid is added to the separated liquid obtained in step (6). Is added, and then heated and concentrated to form a sulfate group of metal group A.

  In yet another embodiment of the method according to the present invention, the waste battery, the waste cathode material or a mixture thereof contains Co, Ni and Mn as the metal group A.

  In yet another embodiment of the method according to the present invention, the waste battery, the waste cathode material or a mixture thereof contains C, P, F, Fe, Cr, Al and Cu as impurities.

  In still another embodiment of the method according to the present invention, steps (2) to (5) are all performed in the order of step (2) → step (3) → step (4) → step (5). The

  In a further embodiment of the method according to the invention, the sulfuric acid leaching is carried out with the addition of a reducing agent.

  In still another embodiment of the method according to the present invention, after the mixed hydroxide of the metal group A is precipitated in the step (7), repulp washing is performed on the mixed hydroxide at least once. Including that.

  In still another embodiment of the method according to the present invention, the extractant used for the solvent extraction in the step (4) contains di-2-ethylhexyl phosphate and an adoxime extractant.

  In another aspect, the present invention is a method for producing a positive electrode active material, comprising using a mixture of metal salts obtained by the method according to the present invention as a raw material for the positive electrode active material.

  In one embodiment of the method for producing a positive electrode active material according to the present invention, the positive electrode active material is for a lithium ion battery.

  According to the present invention, the metal group A consisting of at least two of Co, Ni, and Mn is recovered as a mixture of metal salts from a waste battery, a waste cathode material, or a mixture thereof, so that the labor of separating them individually is eliminated. it can. As a result, it seems to contribute greatly to the reduction of the regeneration cost of the positive electrode material.

  The ratio of Co, Ni, and Mn contained in the recovered metal salt is not constant, but the ratio of Co, Ni, and Mn contained in the metal salt can be confirmed by component analysis. Therefore, when regenerating the positive electrode active material, if the ratio is not appropriate, the ratio can be adjusted by adding a desired amount of arbitrary components of Co, Ni, and Mn.

<Raw material>
In the present invention, the metal group A is recovered as a mixture of metal salts using a waste battery, a waste cathode material or a mixture thereof as a raw material. The waste battery, the waste cathode material, or a mixture thereof is not particularly limited as long as it contains at least two kinds of Co, Ni and Mn, typically these three kinds of metal group A and impurities. Waste cathode material containing positive electrode active material for batteries, incinerated and dried positive electrode active material (possibly mixed with negative electrode active material and solvent (PVDF and NMP)), aluminum foil, etc. A positive electrode material in which a positive electrode active material is bonded to a current collector through a binder, a material in which the positive electrode active material is separated from the positive electrode material, and a battery generally called a battery tub or battery pulverized powder are incinerated, crushed, and sieved. And the like, in which the positive electrode active material is separated.

  As the impurities contained in the waste battery, the waste cathode material, or a mixture thereof, various impurities can be considered, but typically one or more of C, P, F, Fe, Cr, Al, and Cu are included. . These are usually present in the form of various compounds in addition to simple substances. In the present invention, impurities are distinguished for convenience into an impurity element group B consisting of at least one of C, P and F and an impurity element group C consisting of at least one of Fe, Cr, Al and Cu. The impurity element group B is a non-metallic element, and the impurity element group C is a metallic element. In the regeneration of the positive electrode material, it has been considered that sufficient consideration has not been made so far to consider the removal of nonmetallic elements. In the present invention, the removal of such non-metallic elements is also taken into consideration, and the purity of the recovered metal salt mixture is increased.

  In many cases, Li is also included in the raw material in a significant proportion. Li is a component constituting the positive electrode active material of the lithium ion battery, and is not an impurity. Therefore, there is no problem that Li is contained in the metal salt mixture recovered by the method according to the present invention. However, the present invention focuses on the recovery of Co, Ni, and Mn regardless of the recovery efficiency of Li.

<Step (1)>
In the step (1), sulfuric acid is leached from a waste battery, a waste cathode material or a mixture thereof to obtain a leachate. By sulfuric acid leaching, impurities soluble in sulfuric acid as well as Co, Ni and Mn migrate into the leaching solution. When C derived from a binder, a negative electrode active material, or the like is contained as an impurity in the raw material, since C is often insoluble in sulfuric acid, most of C can be removed during sulfuric acid leaching. The sulfuric acid leaching is desirably performed under the following conditions, for example, mainly from the viewpoint of the recovery efficiency of Co, Ni, and Mn.
When the liquid temperature at the time of leaching is too low, the reaction rate is slow, so 20 ° C or higher is preferable, 40 ° C or higher is more preferable, and 60 ° C or higher is even more preferable. On the other hand, if the liquid temperature at the time of leaching is too high, it exceeds the durability of the equipment or equipment, so 90 ° C. or lower is preferable, and 80 ° C. or lower is more preferable.
If the pH during leaching is too low, the amount of alkali used in the subsequent step increases, so it is preferably 2 or more, and more preferably 3 or more. On the other hand, if the pH during leaching is too high, the leaching rate is lowered, so 5 or less is preferable.
Although it is possible to separate the residue from the leachate by solid-liquid separation before moving to the next step, it is also possible to move directly to the next step without solid-liquid separation from the viewpoint of cost reduction.

Since the metal component in the raw material often exists as an oxide, the oxide is not easily leached. Therefore, when Co, Ni, or Mn exists as an oxide and the leaching rate is low only with sulfuric acid, a reducing agent such as sodium sulfite, SO ₂ gas, hydrazine, hydrogen peroxide, etc. is added, and these are reduced and leached. It is preferable to increase the leaching rate. Whether Co, Ni or Mn has been reduced can be determined by the oxidation-reduction potential. When there are many positive electrode materials in which Co, Ni, or Mn is present as a composite oxide, the redox potential (ORP: Ag / AgCl standard) when sulfuric acid is added may exceed 800 mV. In such a case, the ORP can be lowered by adding a reducing agent thereto. From the viewpoint of sufficiently reducing Co, Ni or Mn, the ORP is preferably set to 600 mV or less. Of course, the ORP may be 100 mV or less immediately after the addition of sulfuric acid, in which case it is not necessary to add a reducing agent. For example, the fired product of the battery case may depend on the firing conditions, but it may not be necessary to add a reducing agent when the ORP is sufficiently low even when only sulfuric acid is added.

<Step (2)>
P may be contained in the impurity element group B. P is derived from, for example, an electrolytic solution. In this case, a Fe ³⁺ supply source, for example, ferric sulfate (Fe ₂ (SO ₄ ) ₃ ) is added to the leachate obtained in step (1) to precipitate iron phosphate, and P is It is desirable to remove. At this time, it is desirable to carry out under the following conditions, mainly from the viewpoint of P removal efficiency. In the present invention, ferric sulfate is a concept including ferric sulfate. Other sources of Fe ³⁺ include iron chloride (FeCl ₃ ), iron oxide (Fe ₂ O ₃ ), and the like. There is no particular limitation as long as it can dissolve in water and supply Fe ³⁺ . In addition, after adding and dissolving Fe scraps or the like, Air can be blown into trivalent Fe ³⁺ ions for use.

If the addition amount of the Fe ³⁺ source is too small, sufficient P removal efficiency cannot be obtained, so 1 equivalent or more is preferable with respect to P, 1.2 equivalents or more is more preferable, and 1.3 equivalents or more are further added. Is more preferable. On the other hand, since iron will become excessive when there is too much addition amount, 1.5 equivalent or less is preferable and 1.4 equivalent or less is more preferable.
If the pH of the solution is too low, iron phosphate does not precipitate, so 3 or more is preferable, and 3.5 or more is more preferable. On the other hand, if the pH of the solution is too high, there is a problem that Co and Ni are precipitated, and the amount of precipitation of Co and Ni increases, so 6 or less is preferable, and 5 or less is more preferable.

<Step (3)>
At least one of Fe and Cr may be included in the impurity element group C, and sometimes all of these may be included. Fe is derived from, for example, a housing. Cr is derived from, for example, a housing. In this case, a basic neutralizing agent is added to the leachate obtained in step (1), the pH of the leachate is adjusted to a range of 5 to 6, and the neutralized product of the metal is precipitated, It is desirable to remove the metal element. At this time, it is desirable to carry out, for example, under the following conditions mainly from the viewpoint of the removal efficiency of these metal elements.

Examples of the basic neutralizing agent include, but are not limited to, sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia and the like, and sodium hydroxide is preferable from the viewpoint of handling.
If the pH of the liquid is too low, precipitation does not occur, so 5 or more is preferable, and 5.5 or more is more preferable. On the other hand, if the pH of the solution is too high, the amount of Co and Ni precipitated increases, so 6.5 or less is preferable and 6 or less is more preferable.

<Process (4)>
The impurity element group C may contain Al and Cu. For example, Al is derived from, for example, a current collector, a housing, and the like. Cu is derived from, for example, a current collector, a lead wire, and a substrate. In this case, it is desirable to perform a step of separating Cu and Al to the solvent side by solvent extraction from the leachate obtained in step (1) to remove these metal elements. At this time, it is desirable to carry out under the following conditions, for example, mainly from the viewpoint of the removal efficiency of Al and Cu.

  If the pH of the leachate is too low, it will be difficult to adjust the pH during solvent extraction, while if it is too high, cobalt and nickel may be extracted. Therefore, the pH of the leachate is preferably adjusted to 1.0 to 5.0, more preferably 2.5 to 4.5. The pH adjustment method is not particularly limited, and any known method may be used. For example, an alkali or an acid may be added. Alkaline is often added because the typical post-leaching solution has a low pH of about 1.0 to 3.0. In that case, due to environmental problems such as odor and ease of handling. Sodium hydroxide or ammonia alkali is preferably used, and sodium hydroxide is more preferably used.

  Although it does not limit as an extracting agent, It is preferable to mix and use a phosphate ester type extractant (first extractant) and an oxime type extractant (second extractant). By using a phosphate ester-based and oxime-based extractant in combination, the separation efficiency of both Cu and Al is significantly improved.

  Examples of the phosphate-based extractant that is the first extractant include, but are not limited to, di-2-ethylhexyl phosphate (trade name: D2EHPA or DEHPA).

  Examples of the oxime-based extractant that is the second extractant include aldoxime and aldoxime. Specifically, but not limited to, 2-hydroxy-5-nonylacetophenone oxime (trade name: LIX84), 5-dodecyl salicylaldoxime (trade name: LIX860), a mixture of LIX84 and LIX860 (trade name: LIX984), 5-nonylsalicylaldoxime (trade name: ACORGA M5640), among which 5-nonylsalicylaldoxime is preferred mainly due to price reasons.

  The volume ratio of the first extractant and the second extractant is not particularly limited, but the second extractant is originally an extractant that selectively extracts copper, and the second extractant plays a role in promoting copper extraction. It is preferable that the volume of the second extractant is small with respect to the first extractant because of the fact that a large amount of the second extractant and a large amount of the second extractant require a large amount of acid to back-extract copper. For example, the volume ratio of the first extractant and the second extractant is preferably 1st extractant: 2nd extractant = 1: 1 to 50: 1, more preferably 2: 1 to 25: 1. preferable.

  The extractant can typically be used after diluted with a hydrocarbon-based organic solvent. Examples of the organic solvent include aromatic, paraffinic and naphthenic solvents. In one embodiment, the total concentration of the first extractant and the second extractant in the mixed extractant can be diluted to 10 to 40% by volume, and the viscosity, phase separation, extraction rate, and extraction volume can be reduced. It is preferable to dilute so that it may become 20-30 volume% for a reason.

  The extraction procedure may follow a conventional method. For example, the leachate (aqueous phase) and the extractant (organic phase) are brought into contact, and these are typically stirred and mixed with a mixer (eg, 200 to 500 rpm for 5 to 60 minutes). The ions are reacted with the extractant. Extraction is preferably performed at room temperature (eg, 15 to 25 ° C.) to 60 ° C. or less, and is preferably performed at 30 to 50 ° C. for reasons of extraction speed, phase separation, and evaporation of the organic solvent. The equilibrium pH during extraction is preferably 2.0 to 4.0, but more preferably 2.7 to 3.0 for reasons of extraction rate and generation of Al hydroxide. When the extraction reaction occurs, the pH tends to decrease, but the pH can be adjusted by appropriately adding an alkali such as sodium hydroxide during the extraction. Thereafter, the mixed organic phase and aqueous phase are separated by a difference in specific gravity with a settler. The solvent extraction may be repeated, for example, a multi-stage system in which the organic phase and the aqueous phase are in countercurrent contact.

  The O / A ratio (volume ratio of the oil phase to the water phase) depends on the content of the metal to be extracted, but is preferably set to 0.1 to 20 in consideration of operation with a mixer settler, and 0.2 to 10 is preferable. More preferred.

<Step (5)>
F may be contained in the impurity element group B. F is derived from, for example, an electrolytic solution and a binder. Since the binder itself is a resin, it does not leach with acid, but F derived from the binder due to thermal decomposition when the battery is heated in an incinerator is also conceivable. In this case, it is desirable to remove F by adding a calcium compound to the leachate obtained in step (1) and adjusting the pH to a range of 5 to 8 to precipitate calcium fluoride. Examples of the calcium compound include calcium hydroxide, calcium oxide, calcium chloride, calcium sulfate, calcium alkoxide, and calcium carboxylate. However, since it is necessary to pay attention to waste liquid treatment for organic substances, calcium hydroxide, calcium oxide, calcium chloride, and calcium sulfate are preferable. These may be used alone or in combination of two or more. Step (5) is preferably carried out, for example, under the following conditions, mainly from the viewpoint of F removal efficiency.

If the amount of the calcium compound added is too small, sufficient F removal efficiency cannot be obtained, so 1 equivalent or more is preferable with respect to F in the liquid, 1.1 equivalent or more is more preferable, and 1.2 equivalent or more is even more. preferable. On the other hand, if the addition amount is too large, precipitation of calcium sulfate and precipitation of Co and Ni occur, so 1.5 equivalents or less is preferable, 1.4 equivalents or less is more preferable, and 1.3 equivalents or less is even more preferable.
If the pH of the solution is too low, CaF ₂ does not precipitate, so 5 or more is preferable, and 6 or more is more preferable. On the other hand, if the pH of the liquid is too high, precipitation of Co or Ni occurs, so 8 or less is preferable.

<Combination of steps (2) to (5)>
The steps (2) to (5) described above can be performed in combination in any order depending on the impurities contained in the raw material. For example, when P and F are included in the raw material among the elements constituting the impurity element group B, the step (2) and the step (5) can be combined. Further, when all of Fe, Cr, Al and Cu constituting the impurity element group C are contained in the raw material, the step (3) and the step (4) can be combined. Furthermore, when all of P, F, Fe, Cr, Al, and Cu are contained as impurities regardless of the presence or absence of C, all of the steps (2) to (5) can be combined.

  Steps (2) to (5) are preferably performed in the order of step (2) → step (3) → step (4) → step (5), including the case where some steps are omitted. . This is because the amount of medicine used can be reduced.

<Step (6)>
Among the steps (2) to (5), after performing at least the last step, a step of separating impurities from the leachate by solid-liquid separation is performed. For example, when only steps (2) and (5) are performed in sequence, it is possible to separate the solid and liquid at the end of each of steps (2) and (5) and remove the precipitate generated in that step. It is also possible to perform solid-liquid separation after the last step (5) is completed from the viewpoint of cost reduction without interposing a solid-liquid separation step between steps (2) and (5). Means that. Although it is preferable in terms of process control to remove the precipitate generated in each process from the viewpoint of process control, the present invention can be implemented if solid-liquid separation is performed after at least the last process (5) is completed. is there.

  The solid-liquid separation method is not particularly limited, and may be a known method such as filtration, pressing, decanting, and centrifugation. Filtration and pressing are preferred because of the low water content of the recovered material.

<Step (7)>
The leachate cleaned through the step (6) contains at least one of Mn, Co, and Ni with high purity. In the present invention, these are recovered as a mixture of metal salts without separating them from the leachate. Since there is no effort to separate them individually, this leads to a reduction in the regeneration cost of the positive electrode material. The mixture of metal salts is not particularly limited, but can be recovered in the form of hydroxide, sulfate, carbonate, nitrate, hydrochloride and the like. The metal salt can be in the form of an aqueous solution, but it is more convenient to use a solid in consideration of transportation costs and the like. As a specific example, a method of recovering as a hydroxide and a sulfate is shown below.

First, a method for recovering as a hydroxide will be described. A basic neutralizing agent is added to the separation liquid obtained in the step (6) to adjust the pH of the leachate to a range of 8 to 12, and the mixed hydroxide of the metal group A is precipitated to mix the metal group A. The hydroxide can be recovered on the solid side by solid-liquid separation. At this time, it is desirable to carry out under the following conditions, for example, mainly from the viewpoint of recovery efficiency of the metal element group A and impurity reduction.
Examples of the basic neutralizing agent include, but are not limited to, sodium hydroxide and potassium hydroxide, and sodium hydroxide is generally used.
If the pH of the liquid is too low, precipitation does not occur, so 8 or more is preferable, and 8.5 or more is more preferable. On the other hand, if the pH of the solution is too high, Na increases, so it is preferably 12 or less, and more preferably 11 or less.
The solid-liquid separation method is not particularly limited, and may be a known method such as filtration, pressing, decanting, and centrifugation. Filtration and pressing are preferred because of the low water content of the recovered material.

  After the mixed hydroxide of the metal group A is precipitated, it is preferable to perform repulp washing on the mixed hydroxide at least once, desirably a plurality of times, in order to reduce impurities.

  Next, a method for recovering as a sulfate will be described. Alternatively, a sulfuric acid mixture of metal group A can be produced by adding sulfuric acid to the separation liquid obtained in step (6) and then concentrating with heating. Heating concentration can be performed using an evaporator, a refrigerator, or the like. At this time, it is desirable to carry out under the following conditions, for example, mainly from the viewpoint of recovery efficiency of the metal element group A and impurity reduction.

  If the sulfuric acid concentration in the solution before heating and concentration is too low, crystals do not precipitate, and therefore it is preferably 10 g / L or more, more preferably 50 g / L or more.

<Manufacture of positive electrode active material>
A positive electrode active material can be produced using a mixture of metal salts recovered by the above method according to the present invention as a raw material, and in particular, a positive electrode active material for a lithium ion battery can be suitably produced. A typical positive electrode active material is composed of a composite oxide containing a transition metal such as cobalt, nickel, and manganese in addition to lithium. The manufacturing method of the positive electrode active material itself is publicly known, and it is considered that no explanation is required.

  Depending on the composition of the target metal composite oxide, the metal salt in the form of sulfate, nitrate, hydrochloride, carbonate, hydroxide, etc. is wet mixed to the desired molar ratio, and alkali precipitation is performed. The composite of lithium and transition metal is prepared by a known technique such as a sol-gel method, a sol-gel method, or a spray pyrolysis method. A positive electrode active material can be obtained by heat-treating these composites. By analyzing in advance the components of the metal salt obtained by the method according to the present invention, a metal composite oxide having a desired composition can be prepared. It is naturally possible to add a metal other than cobalt, nickel, and manganese as the metal constituting the positive electrode active material.

  Examples of the present invention will be described below, but the examples are for illustrative purposes and are not intended to limit the invention.

(Example 1)
100 g of incinerated crushed powder obtained by incineration, crushing, and sieving a lithium ion battery having the composition shown in Table 1 was prepared. The composition analysis was ICP analysis by dissolving aqua regia except F and C. F was measured by an ion electrode after distilling aqua regia dissolved. C was measured by a combustion method.

  400 mL of pure water and 62.7 mL of 98% by mass concentrated sulfuric acid were added to this and stirred, and leaching was performed under the conditions of liquid temperature: about 70 ° C., ORP (Ag / AgCl standard): about 0 mV, final pH: about 2.5. For 2 hours and filtered. Table 2 shows the concentration analysis results of the leachate after filtration. It can be seen that C and Cu are almost removed. Analysis was performed by ICP. However, F was distilled and measured with an ion electrode. C was measured with a TOC measuring machine.

  Next, 3.8 g of ferric sulfate (210 g / L aqueous solution) was added to about 460 mL of the leachate, and subsequently 25% by mass aqueous sodium hydroxide solution was added to adjust the pH to 5.0. Generated. The precipitate was removed by filtration. Table 3 shows the concentration analysis results on the liquid side after the precipitate was formed. It can be seen that Fe, Cr and P are almost removed. Cu and Al were also removed significantly, but not enough. Concentration analysis was performed by ICP. However, F was distilled and measured with an ion electrode. C was measured by measurement with a TOC measuring device.

Then, 21% by volume of di-2-ethylhexyl phosphoric acid (trade name: D2EHPA), 4% by volume of 5-nonylsalicylaldoxime (trade name: ACORGA M5640), and an organic solvent mainly composed of a linear hydrocarbon ( An extractant containing 75% by volume of trade name: Shellsol D70) was prepared.
The leachate and the extractant were mixed and stirred (300 rpm) using a countercurrent multi-stage mixer settler (number of extraction stages: 3 stages) so that the O / A ratio = 0.5, and solvent extraction was performed. At this time, a sodium hydroxide solution for pH adjustment was added to the mixer settler. The equilibrium pH at the time of extraction was 2.8. The stirring time in each extraction stage was 15 minutes. The liquid temperature at the time of extraction was maintained at 35 to 40 ° C. Table 4 shows the concentration of each element in the liquid after extraction (aqueous phase). It can be seen that Cu and Al are almost removed. Concentration analysis was performed by ICP. However, F was distilled and measured with an ion electrode. C was measured by measurement with a TOC measuring device.

  Next, when 3.2 g of powdered calcium hydroxide was added to the leachate (= liquid after extraction), a precipitate of calcium fluoride was formed. At this time, the pH changed to about 7.0. The results of concentration analysis on the liquid side are shown in Table 5. It can be seen that F is almost removed. Concentration analysis was performed by ICP. However, F was distilled and measured with an ion electrode. C was measured by measurement with a TOC measuring device.

  After separating the precipitate by filtration, a 25% by weight aqueous sodium hydroxide solution was added to the leachate to adjust the pH to 9.5. As a result, a hydroxide precipitate mainly composed of Mn, Co and Ni was produced. . The results of concentration analysis on the liquid side are shown in Table 6. Concentration analysis was performed by ICP. However, F was distilled and measured with an ion electrode. C was measured by measurement with a TOC measuring device.

  The precipitate was collected by filtration using a filter press and washed with water. As a result, solids of a mixture of Mn, Co and Ni hydroxides having the grades shown in Table 7 were obtained. The composition analysis was ICP analysis by dissolving aqua regia except F and C. F was measured by an ion electrode after distilling aqua regia dissolved. C was measured by a combustion method.

  Furthermore, when repulp washing (repulp concentration 100 g / L) and filtration using a filter press were repeated twice, solids of a mixture of Mn, Co and Ni hydroxides of the grade shown in Table 8 were obtained. The composition analysis was ICP analysis by dissolving aqua regia except F and C. F was measured by an ion electrode after distilling aqua regia dissolved. C was measured by a combustion method. It can be seen that the Na concentration was significantly reduced.

(Example 2)
The same operation as in Example 1 was performed until a precipitate of calcium fluoride was produced from 100 g of the waste cathode material of the same lithium ion battery as in Example 1 and the precipitate was separated by filtration. Thereafter, 10 g of 98% by mass concentrated sulfuric acid was added to 200 mL of the obtained leachate. Table 9 shows the concentration analysis results of the obtained liquid. Concentration analysis was performed by ICP. However, F was distilled and measured with an ion electrode. C was measured by a TOC measuring device, and the acid concentration was measured by an acid concentration measuring device.

  When this liquid was heated and concentrated with an evaporator, solids of a mixture of sulfates of Mn, Co and Ni having the grades shown in Table 10 were obtained. ICP analysis was performed after dissolving in aqua regia except for F and C. F was measured by an ion electrode after distilling aqua regia dissolved. C was measured by a combustion method.

Claims (12)

A metal group A composed of at least two of Co, Ni and Mn, an impurity element group B composed of at least one of C, P and F, and an impurity element group C composed of at least one of Fe, Cr, Al and Cu. A method for recovering the metal group A from a contained waste battery, a waste cathode material, or a mixture thereof, comprising carrying out steps (1) to (7) according to the following conditions .
Step (1): A step of leaching sulfuric acid from a waste battery, a waste cathode material or a mixture thereof to obtain a leachate,
Step (2): if it contains P in an impurity element group B, step to precipitate the iron phosphate by addition of Fe ³⁺ source leachate,
Step (3): When at least one of Fe and Cr is contained in the impurity element group C, a basic neutralizing agent is added to the leachate, and the pH of the leachate is adjusted to a range of 5 to 6 in the metal. A step of precipitating the sum,
Step (4): When Al and Cu are contained in the impurity element group C, a step of separating Cu and Al from the leachate by solvent extraction to the solvent side,
Step (5): When F is contained in the impurity element group B, a step of adding calcium compound to the leachate and precipitating calcium fluoride by adjusting the pH to a range of 5 to 8,
Step (6): A step of separating impurities from the leachate by performing solid-liquid separation after performing at least the last step among steps (2) to (5),
Step (7): A step of recovering the metal group A as a mixture of metal salts from the separated liquid obtained in the step (6).   The method of claim 1, wherein the metal salt is a solid. The method according to claim 1 or 2 , wherein the metal salt is a hydroxide, sulfate, carbonate, or nitrate. In the step (7), a basic neutralizing agent is added to the separation liquid obtained in the step (6) to adjust the pH of the leachate to a range of 8 to 11, and the mixed hydroxide of the metal group A is precipitated. The step of recovering the mixed hydroxide of metal group A to the solid side by solid-liquid separation, or the addition of sulfuric acid to the separated liquid obtained in step (6), followed by concentration by heating, causes the sulfuric acid of metal group A The method according to any one of claims 1 to 3 , which is a step of forming a salt mixture. The method according to any one of claims 1 to 4 , wherein the waste battery, the waste positive electrode material, or a mixture thereof contains Co, Ni, and Mn as the metal group A. The method according to any one of claims 1 to 5 , wherein the waste battery, the waste cathode material or a mixture thereof contains C, P, F, Fe, Cr, Al and Cu as impurities. The method according to any one of claims 1 to 6 , wherein the steps (2) to (5) are performed in the order of the step (2)-> step (3)-> step (4)-> step (5). . The method according to any one of claims 1 to 7 , wherein the sulfuric acid leaching is carried out by adding a reducing agent. 5. The method according to claim 4 , wherein after the mixed hydroxide of metal group A is precipitated in step (7), repulp washing is performed on the mixed hydroxide at least once. The method as described in any one of Claims 1-9 in which the extractant used for the solvent extraction of a process (4) contains di-2-ethylhexyl phosphoric acid and an adoxime type extractant. The manufacturing method of a positive electrode active material including using the mixture of the metal salt obtained by the method as described in any one of Claims 1-10 as a raw material of a positive electrode active material. The manufacturing method according to claim 11 , wherein the positive electrode active material is for a lithium ion battery.