JP2013001951A - Dialysis promotor and metal recovery method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recovering valuable metals from a lithium-ion battery by a relatively simple facility without using a complicated process.SOLUTION: A positive electrode material of the lithium-ion battery including lithium and transition metal elements is dissolved in an acidic solution to generate lithium ions and transition metal ions in the acidic solution, the acidic solution and a recovering solution are passed through an anion-permeable membrane to dialyze lithium ions from the acidic solution to the recovering solution, and lithium ions are recovered from the recovering solution in which the lithium ions are dissolved by the dialysis. In this case, an additive which destroys the hydration structure of lithium ions is added, whereby the permeability rate of lithium ions to the permeable membrane is improved, and lithium selective passing rate and recovery rate are improved.

Description

  The present invention relates to a method for recovering valuable metals from a positive electrode member of a lithium ion battery and a dialysis treatment solution.

  In recent years, the usage amount of secondary batteries has been rapidly increasing as electronic devices have become more portable. Rechargeable batteries are widely used not only for devices with relatively low power, such as mobile phones and portable music players, but also for devices that require high power, such as electric tools, electric bicycles, and electric vehicles, resulting in high energy density. Attention has been focused on the resulting lithium ion battery. Due to the increase in application to high-power devices, the necessity of recovering valuable materials from used batteries is increasing, and various techniques for recovering valuable metals from lithium ion batteries have been proposed.

  For example, Non-Patent Document 1 features a lithium-ion battery recycling technique, and systematically describes a method for recovering valuable metals constituting the lithium-ion battery. According to a typical recycling method published in Non-Patent Document 1, for example, a used lithium ion battery dissolves valuable metals by acid leaching after mechanical processing such as opening, dismantling, and grinding, Using the difference in solubility characteristics for each desired component, the components are separated and collected for each desired component by a process such as separation for each component to form a precipitate, or solvent extraction of the desired component preferentially.

  Patent Document 1 proposes a copper and cobalt recovery technique using diaphragm electrolysis using a valuable metal obtained by acid leaching as a catholyte and using a solution and a cation exchange membrane as a diaphragm. In this technique, exudate acid can be circulated and used in combination with diffusion dialysis using an anion exchange membrane.

Japanese Patent No. 3675392

Jinqiu Xu et al. , “A review of processes and technologies for the recycling of lithium-ion secondary batteries”, Journal of Power Sources, vol. 177, pp. 512-527 (2008) Yanjie Zhang et al. , “Specific Ion Effects on the Water Solubility of Macromolecules: PNIPAM and the Hofmeister Series,” Journal of American Chemical Society. 127, pp. 4505-14510 (2005)

  Non-Patent Document 1 aims at improving both the recovery rate of valuable materials and increasing the purity of recovered materials by various devices, but the process is complicated and it is enormous for processing a large amount of waste batteries. There is much room for improvement in terms of capital investment.

In patent document 1, the characteristic which an ion exchange membrane has is utilized well, and highly purified collection | recovery is implement | achieved with a comparatively simple installation. Specifically, a relatively simple facility (diaphragm electrolysis cell shown in FIG. 2 of Patent Document 1) utilizing the ion selective characteristics of the cation exchange membrane and a diffusion dialysis facility utilizing the anion selectivity of the anion selective membrane (No explanatory diagram) is used. More specifically, electrodeposition recovery of copper by diaphragm electrolysis → pH adjustment → electrodeposition recovery of cobalt by diaphragm electrolysis → pH adjustment → precipitation recovery of Fe (OH) ₃ and Al (OH) ₃ → by carbonate addition All the main valuable metals can be recovered by a series of processes called Li ₂ CO ₃ recovery. According to this technology, copper (divalent ions) and cobalt (trivalent ions) are electrochemically reduced and recovered, so that a high-purity metal can be obtained. However, when treating a large amount of waste batteries, There is room for improvement in that a huge amount of electricity needs to be applied.

For example, in order to recover about 100 kg of cobalt, it is necessary to continue a current of 1 ampere for about 100 hours, but before that, almost the same amount of electricity is applied even in the electrodeposition of copper. Just recovering all the metal is an extraordinary effort. Furthermore, since the amount of liquid increases each time multi-stage pH adjustment is performed, the concentration of lithium is reduced when Li ₂ CO ₃ is recovered in the final stage of a series of treatments. Often, the lithium recovery is not necessarily high. This is because the saturated solubility of lithium carbonate is 1.3 wt% at 20 ° C., so that the unrecovered components increase as the liquid amount increases. In order to avoid this, processing such as adding a concentration step is necessary. Further, since Fe (OH) ₃ and Al (OH) ₃ tend to be gelled in a weakly acidic to neutral aqueous solution, Fe (OH) ₃ and Al (OH) are based on the technique of Patent Document 1. The operation of the step of collecting ₃ by filtration is not easy. On the other hand, when the liquid is diluted to facilitate the filtration operation, the lithium recovery rate is lowered. Moreover, since the surface of the gel-like precipitate of Fe (OH) ₃ or Al (OH) ₃ also has a characteristic of adsorbing lithium ions, it is difficult to significantly improve the lithium recovery rate from this viewpoint.

  An object of the present invention is to provide a method for efficiently recovering valuable metals from a lithium ion battery without using a complicated process as in the prior art and using relatively simple equipment.

  The following is a brief description of an outline of typical inventions disclosed in the present application.

  As a substance that affects the lithium ion membrane permeation rate, the hydrated structure is destroyed and the apparent lithium ion size is reduced in the solution obtained by leaching the positive electrode active material containing lithium and transition metal elements. Add a functional substance, followed by dialysis.

  According to the present invention, lithium ion hydration water is removed before dialysis, the apparent lithium ion size is reduced, and dialysis in that state increases the lithium ion membrane permeation rate, thereby selecting lithium. The transmittance and the recovery rate can be improved.

It is the process flow outline for collect | recovering valuable metals of the 1st Example which concerns on this invention. 1 is a schematic view showing one embodiment of a dialysis apparatus using a dialysis membrane according to an example of the present invention. In the substance which destroys the hydration structure of the lithium ion which concerns on this invention, it is a figure which shows the relationship between the order of the destructive power of the hydration structure especially about guanidates, and a molecular structure factor. In the substance which destroys the hydration structure of the lithium ion which concerns on this invention, it is a figure which shows the relationship between the order of the destructive force of the hydration structure especially about an organic compound, and a molecular structure factor. It is a result of the Li / Co concentration ratio by the dialysis treatment which concerns on this invention.

  Hereinafter, embodiments for carrying out the present invention will be described. In the description with reference to the drawings, each component constituting the drawing is provided with a reference numeral, and the description is omitted in the case of the same function. In addition, the dimensions of the parts shown in the drawing may not necessarily match the scale reflecting the actual part dimensions.

  FIG. 1 shows an outline of a process flow of metal recovery from the waste lithium ion battery (hereinafter referred to as a waste battery) of this example.

  In order to recover valuable metals from a waste lithium battery (hereinafter referred to as a waste battery), it is necessary to first disassemble the battery (S101). Prior to disassembly, the charge that may remain in the battery is discharged. .

  In this embodiment, the charge remaining in the battery is discharged by immersing the battery in a conductive liquid containing an electrolyte. In the present embodiment, a sulfuric acid / γ-butyrolactone mixed solution is used as the conductive liquid containing the electrolyte. Since sulfuric acid acts as an electrolyte in this mixed solution, the conductivity (reciprocal of the resistance value) was adjusted by adjusting the sulfuric acid concentration. In this example, when the electric resistance of the solution was measured over the distance from the right end to the left end of the discharge tank, it was 100 kΩ. If the resistance value of the solution is too small, the discharge proceeds too rapidly, which is dangerous. On the other hand, if the resistance value is too large, the discharge takes too much time and the practicality deteriorates. In this embodiment, the solution resistance is preferably in the range of about 1 k to 1000 kΩ, and the electrolyte concentration may be adjusted to fall within this resistance value range.

  Suitable electrolytes in this embodiment include sulfuric acid, acids such as hydrochloric acid, nitric acid, formic acid, salts such as ammonium nitrate, ammonium sulfate, calcium nitrate, magnesium sulfate, potassium hydroxide, cesium hydroxide, lithium hydroxide, tetramethyl Bases such as ammonium hydroxide; Solvents for dissolving these electrolytes to form conductive liquids include γ-butyrolactone, sulfolane, propylene carbonate, ethylene carbonate, NMP (N-methylpyrrolidinone), dimethoxyethane, tetramethylurea, dimethylimidazo Lidinone, dimethyl sulfone, water, acetonitrile, or a mixture thereof can be used.

  Needless to say, the waste battery of the present invention is not limited to the so-called used battery that has reached the limit of the number of charge / discharge cycles and the charge capacity has been reduced. This includes semi-finished products caused by malfunctions, old-type inventory items that arise as product specifications change.

  For the battery after the discharge treatment, the battery components such as the case, packing / safety valve, circuit elements, spacer, current collector, separator, positive electrode and negative electrode active material are used for each member by an appropriate method. Separate (S102). In addition, since waste lithium ion batteries are often filled with gas and are in a pressurized state, needless to say, work safety considerations are necessary. In this example, wet pulverization was performed while cooling in a state of being immersed in a conductive liquid containing an electrolyte. By adopting the wet pulverization under cooling, the gas filled in the battery could be safely crushed without being scattered in the atmosphere. In addition, in order to promote the peeling of the positive electrode active material and the negative electrode active material coated and molded on the current collector surface from the respective current collector surfaces, the composition of the conductive liquid containing the electrolyte that dissolves the electrolyte is changed. It can be adjusted. In addition, in the conductive liquid used for a discharge process, electroconductivity should be noted, and in the electroconductive liquid used in a wet pulverization process, viscosity and dielectric constant should be noted. Since the required specifications differ between the discharge process and the wet pulverization process, the composition of the conductive liquid used in each process may be changed. In that case, it is necessary to prepare two or more kinds of conductive liquids. In this example, the same composition was used from the viewpoint of simplification and reduction of labor and cost.

As a wet pulverization method that can be used in this embodiment, there is a method such as a ball mill, but it is not necessarily limited thereto. Of the components such as housings, packing / safety valves, circuit elements, spacers, current collectors, separators, and electrode active materials, the positive electrode active material (positive electrode active material) and the negative electrode active material (negative electrode active material) After crushing under the preferential crushing condition, a sieving process is applied. As a result, the positive electrode active material and the negative electrode active material are separated and recovered under the sieve, and the other members are separated and collected on the sieve. In this example, sieving was used, but since it was originally pulverized in a wet manner, the slurry obtained by the wet pulverization can be separated by filtration using a relatively coarse filter as it is. good. The recovery rate may be improved by introducing a continuous process from wet pulverization to filtration. Note that the casing, packing / safety valve, current collector (aluminum foil, copper foil), etc. have a larger spreadability than the positive electrode active material (typically LiCoO ₂ ) or the negative electrode active material (typically graphite). Therefore, the breaking strength is also large. Because of this characteristic, the crushed material of the electrode active material is smaller in size than the crushed material obtained from other members, and as a result, can be easily separated and collected by sieving or filtering.

  Since the negative electrode active material is mixed in the crushed material under the sieve, the positive electrode active material and the negative electrode active material are separated by specific gravity difference separation, and the negative electrode active material is removed.

The negative active material obtained by the above treatment is separated, and the under-sieving material whose main component is only the positive active material is dissolved (exuded) with an exudate composed of mineral acid, organic acid, pure water and the like. (S103). Among the exudates that can be used in this embodiment, as the mineral acid, sulfuric acid, phosphoric acid, nitric acid or a mixed acid thereof can be used in addition to hydrochloric acid. As the organic acid, malic acid, citric acid, oxalic acid, formic acid, acetic acid, or a mixed acid thereof can be used. Further, hydrogen peroxide solution or the like may be added to increase the amount of lithium compound mainly composed of LiCoO ₂ . In consideration of the type and composition of the lithium compound, the treatment amount, the treatment time, the cost, etc., it can be appropriately selected from these. In this example, a mixed solution of sulfuric acid and hydrogen peroxide solution was used as the exudate. LiCoO ₂ and the exudate were mixed and stirred for 1 hour, and then centrifuged at 15000 rpm, 20 ° C. for 15 minutes to separate into solution A (S104) and solid component B (S105) as a residue.

  After the above leaching process is completed, the solid component B (transition metals a, b,...) Remaining undissolved can be removed by filtering the effluent.

  The solution A obtained by leaching is transferred to a dialysis tank using a dialysis membrane and subjected to dialysis (S106). Metal ions contained in the solution A and collected by dialysis are lithium and cobalt (other transition metals). Since lithium and other metal ions have a difference in ionic valence, they can be collected separately by dialysis (S108, S109). Since the components of the solid component B which is the residue of exudation and the transition metals a, b,... Contained in the solution obtained by dialysis treatment contain the same components, they are integrated and recovered in S109, and then each component The transition metals a, b,... Are separated and recovered. The transition metals a and b include, for example, cobalt.

  Details of the dialysis treatment in S106 are as follows. A schematic structure of the dialysis tank 8 used in this embodiment is shown in FIG.

  In the dialysis tank 8 shown in FIG. 2, a solution flow inlet 2 for supplying a solution after filtration and a solution flow through which a recovered solution containing a transition metal such as cobalt flows out from the dialyzed solution. A pressure tank 6 for dialysis provided with an outlet 3, a recovery liquid inlet 4 for supplying a recovery liquid for dialysis recovery of lithium, and an acid and lithium that have permeated through the dialysis membrane 1 are dissolved. A recovery liquid tank 7 having a recovery liquid outlet 5 through which the recovered liquid flows out is provided. The dialysis pressure tank 6 and the recovery liquid tank 7 are connected via the dialysis membrane 1. In this embodiment, as the dialysis membrane 1, Selemion DSV (registered trademark), which is an anion exchange membrane for diffusion dialysis manufactured by Asahi Glass Co., Ltd., was processed and used between the pressurized dialysis tank 6 and the recovery liquid tank 7. . In this embodiment, other ion-exchange membranes can be used, but in that case, it is desirable to select them in consideration of ion transport number and oxidation resistance. Since FIG. 2 shown here is a schematic diagram, the details are omitted, but each inlet / outlet is provided with a flow meter and a pressure gauge, and the dialysis tank 6 and the recovery liquid tank 7 are provided. A liquid meter is provided. Needless to reiterate, in addition to sensors such as conductivity meter, pH meter, ion concentration meter, rectifier mechanism for rectifying the flow of liquid, pressurizing mechanism for pressurizing, for controlling the whole Equipment and equipment necessary for realizing the function of the dialysis tank 8, such as a control mechanism, are provided without excess or deficiency. In addition, for the purpose of maximizing the dialysis function, the flow path arrangement is such that the flow of exudate and the flow of recovered liquid are almost countercurrent on both sides of the dialysis membrane.

  The solution A after acid leaching obtained by S104 is supplied from the solution inlet 2 of the dialysis tank 8 shown in FIG. 2 and flows toward the solution outlet 3, and from the inlet 2 to the outlet 3 It is devised to pass through the surface of the dialysis membrane 1. When passing through the surface of the dialysis membrane 1, lithium ions, acids, etc. dissolved in the solution are adsorbed on the surface of the dialysis membrane 1 and diffused inside the dialysis membrane 1, so that the recovery liquid side And ion exchange.

  Dialysis may be performed by applying pressure such as pressurization, suction, and centrifugation, or may be performed at normal pressure. However, diffusion dialysis alone is not suitable for treating a large amount of waste batteries because it takes a long time to complete dialysis. Since there is a merit that a pressurizing mechanism is unnecessary and energy required for pressurization can be saved, if only small-scale recycling is to be realized at low cost, it can be handled only by diffusion dialysis. On the other hand, if the electrodialysis method described in Japanese Patent No. 3675392 is used, a concentrated recovery solution can be obtained by a single-stage dialysis treatment. However, since electric energy is required for the concentration, only electrodialysis is performed. However, it is not practical to process a huge amount of exudate, and it is desirable to use it together with pressure dialysis.

  In this example, before dialysis, a substance that destroys the hydration structure of lithium ions is added to the solution A (S107). Non-patent document 2 exemplifies sulfate ions, chloride ions, thiocyanate ions, etc. as substances that destroy the hydration structure of ions. Further, Non-Patent Document 2 describes that the permutation of the destructive power of the hydration structure of these anions is as follows.

Sulfate ion> chloride ion> thiocyanate ion The inventors have developed guanidine salts having the above three types of anions (sulfate ion, chloride ion, thiocyanate ion) as counter ions, specifically, guanidine sulfate. We developed a method to measure the hydration structure breaking power of guanidine hydrochloride and guanidine thiocyanate, and found that there is a correlation between the charge density on the nitrogen atom and the hydration structure breaking power. In addition to being able to reproduce the permutation of the destructive force of the anion hydration structure described in Non-Patent Document 2, the measurement method made it possible to evaluate the destructive force of the hydration structure by quantification. The measuring method was performed by TLC (Thin-Layer Chromatography).

  First, a solution containing an ionic substance (lithium ion or cobalt ion) with a needle-like substance such as a capillary is spotted on the end of a silica TLC. When the end face of TLC on which an ionic substance is spotted is immersed in an aqueous solution of each guanidine salt, the spot of the ionic substance moves toward the end face opposite to the spot where the guanidine salt solution is spotted. To do. An ionic substance having a hydrated structure has a higher mobility. Therefore, if the guanidine salt destroys the hydration structure, the binding force of the ionic substance to silica increases, and the spot mobility decreases.

As shown in Equation 1, the mobility Rf of the ionic substance is defined by dividing the movement distance D1 of the ionic substance by the movement distance D2 of the aqueous guanidine salt solution. Rf is related to the binding force of the ionic substance to the TLC surface (silica).
(Expression 1) Rf = D1 / D2
According to the measurement by the inventors, the mobility Rf changed substantially linearly with respect to the concentration C [M] of the aqueous guanidine salt solution. Therefore, the value obtained by the measurement was approximated by the least square method as shown in Equation 2. m and a are constants.
(Expression 2) Rf = m · C + a
And the hydration structure breaking force (DELTA) m of the guanidine salt was defined like Formula 3.
(Equation 3) Δm = m _Co −m _Li
It is shown that the smaller m (the negative value is the larger the absolute value), the more the hydration structure of the ionic substance is destroyed and the binding force with silica is increased, and the movement of the aqueous solution cannot be followed. That is, as Δm is larger, the destructive force of the hydrated structure of lithium ions is higher than the destructive force of the hydrated structure to cobalt ions. In order to obtain high selective dialysis performance, Δm is desirably 2 or more.

  The inventors measured various guanidine salts while changing the concentration. As a result of the study by the inventors, the destructive force of the hydration structure has a correlation with the charge density of the nitrogen atom (hereinafter referred to as charge N) when the molecular structure of the substance contains a nitrogen atom. It was confirmed that there was. The charge density was calculated using CS MOPAC (R) semi-empirical calculation (Cambridgesoft).

  FIG. 3 shows a part of the results of specific experiments conducted by the inventors. Here, the vertical axis represents the charge density of nitrogen atoms (charge N), and the horizontal axis represents the hydration structure breaking force index (arbitrary unit), and the results of the above three types of guanidine salts are plotted. In addition, the density | concentration required in order to form the same hydration structure destruction state was made into the parameter | index of a hydration structure destruction force. The larger the value of the charge N (the smaller the absolute value), the greater the ionic hydration structure breaking force, and the permutation is consistent with the description in Non-Patent Document 2. Moreover, since the charge density (charge N) of the nitrogen atom of guanidine sulfamate is almost equivalent to the charge density (charge N) of the nitrogen atom of guanidine thiocyanate, the hydration structure breaking power of guanidine thiocyanate is As shown in Fig. 3, the hydration structure breakdown power ranking of guanidine sulfamate is located between thiocyanate ion and chloride ion. This has been confirmed by experiments by the inventors.

  As a result of detailed observation and evaluation of the hydration structure breaking behavior of various nonionic substances, the inventors have also found that nitrogen atoms are included in the molecular structure of nonionic substances as well as the above guanidine salts. In other words, it has been found that there is a correlation between the charge density of nitrogen atoms (charge N) and the hydration structure breaking force. Part of the specific experimental results evaluated and measured by the inventors regarding the relationship between the hydration structure breaking force of a nonionic compound containing a nitrogen atom in the molecular structure and the charge density (charge N) of the nitrogen atom 4 shows. When DMI (1,3-dimethyl-2-imidazolidineone) having a large charge N value (small absolute value) is used, it has been found that a large ion hydration structure breaking force can be obtained.

  In the present invention, the greater the destructive force of the ion hydration structure, the higher the rate of removal of lithium ion hydration water and the rate at which Li ions permeate the dialysis membrane. The Li / transition metal selectivity of the recovered liquid is improved. In addition, the amount of substance added can be reduced, and the amount of waste water can be reduced and the processing cost can be reduced.

  Therefore, in this embodiment, DMI is selected as a substance that has a large charge N value as a substance that destroys the hydration structure and is low in price and high in safety from a practical viewpoint, and a predetermined amount of DMI is added. (S107). By dialysis treatment after adding DMI in advance, the hydration structure of lithium ions is destroyed and the apparent ion size (Stokes diameter) of lithium ions contained in the non-dialysis treatment solution is reduced. Can do. As is well known, the Stokes radius of lithium ions in a hydrated state is considerably large, but the Stokes radius of lithium ions in a non-hydrated state is classified into the smallest class among all metal ions. In the dialyzed solution to which a hydrated structure-disrupting substance is added, non-hydrated lithium ions gain a higher ion diffusion rate than other metal ions (transition metals a, b,. Non-hydrated ions in the liquid are more likely to reach the dialysis membrane surface than other metal ions.

  That is, in the system to which a substance that destroys the hydration structure is added as in this example, the decrease in dialysis rate due to the rate of ion supply from the non-dialysis solution to the dialysis membrane surface (diffusion rate control) Is small and a stable dialysis rate can be obtained. On the other hand, other metal ions (transition metals a, b,...) Immediately decrease in dialysis rate due to ion supply rate limiting (diffusion rate limiting) to the dialysis membrane surface. Selective dialysis recovery of ions can be realized. On the other hand, when the hydrated structural destruction substance is not added, the difference between the Stokes radius of the hydrated lithium ion and the Stokes radius of the hydrated ion of other metal ions (transition metals a, b,...) Is not large. Lithium ions, like other metal ions, cause a decrease in dialysis rate due to diffusion rate control, and it may be difficult to achieve ion selectivity in dialysis recovery.

  It is said that dehydration of ions is required when the metal ion species adsorbed on the dialysis membrane surface is taken into (permeates) the dialysis membrane. This is because the inside of the dialysis membrane is a hydrophobic environment. When dialysis is performed without adding a substance that destroys the hydration structure, lithium ions and other metal ions (transition metals a, b,...) Are taken in the same way when they are taken into the dialysis membrane. Although it can be dehydrated, lithium ions having a more complex and multiple hydration structure require higher activation energy for the dehydration process than other metal ions (transition metals a, b,...). . Therefore, compared with other metal ions (transition metals a, b,...), The suppression of the penetration rate of lithium ions in the dialysis membrane by ion dehydration is large (reverse selectivity of lithium ions). On the other hand, as in this example, when a dialysis is performed after adding a substance that destroys the hydration structure in advance, dehydration has already started by the time the metal ion species reaches the diffusion surface on the dialysis membrane surface. The activation energy required for the above is reduced, and the reverse selectivity of lithium ions as described above is less likely to occur.

  It is said that the ion diffusion rate in the dialysis membrane is usually dependent on the number of charges of the ions. Generally, monovalent ions such as lithium ions have a higher dialysis rate than multivalent ions such as transition metal ions. It is known to be big. In this example, by performing dialysis after adding a hydrated structurally disrupting substance, (1) ion diffusion in the solution to be dialyzed (arrival at the dialysis membrane), (2) from the dialysis membrane surface Lithium is preferential in both elementary processes of intramembrane dialysis and (3) diffusion in the dialysis membrane, and as a result, high lithium selectivity by dialysis recovery can be realized. On the contrary, if the hydration structure destruction substance is not added, (1) ion diffusion in the solution to be dialyzed (arrival to the dialysis membrane), (2) elementary process of infiltration into the membrane from the dialysis membrane surface, Since it is a reverse selection for lithium, (3) it is difficult to achieve high lithium selectivity only by dialysis recovery even if lithium is selective in diffusion within the dialysis membrane.

  In order to verify the effect of this example, a mixed solution of the solution A and the additive was supplied to the dialysis tank 8. In this example, ions were leached from the positive electrode material with a mixed solution of sulfuric acid and hydrogen peroxide, and DMI was added as an additive, followed by diffusion dialysis for 50 hours.

  The result is shown in FIG. The Li / Co concentration ratio of the solution A before dialysis is 1. When the dialysis treatment of this solution was performed for 50 hours, the Li / Co concentration ratio in the recovered solution reached 21. On the other hand, when DMI was not added, the Li / Co concentration ratio was 2. Therefore, it can be seen that the selective dialysis property of lithium ions was increased about 10 times by adding a substance that destroys the hydration structure of lithium ions.

  In addition, the obtained lithium recovery solution can be separated from lithium and transition metal such as cobalt by ion exchange resin such as chromatographic technique to further increase the Li / Co concentration ratio.

Thus, high purity lithium can be recovered from the recovered liquid from which impurities and excess acid have been removed (S108). Specifically, there are methods such as pH adjustment and precipitation collection as lithium hydroxide, addition of sodium carbonate to precipitation collection as lithium carbonate, and CO ₂ gas blowing while electrodialysis.

When the positive electrode active material is LiCoO ₂ , cobalt can be recovered with high purity simultaneously with the recovery of lithium.

The positive electrode active material is not limited to LiCoO ₂ and may have a composition containing a transition metal other than Co. In the case of containing a lithium compound, for example, in the case of containing LiNiO ₂ , LiMnO ₂ , LiCo _1/3 Ni _1/3 Mn _1/3 O _2, etc., Co, Ni, Mn can be converted into hydroxides by adjusting the pH of the liquid. Precipitate recovery is possible.

  In this embodiment, the solid component is separated from the acid exudate and the additive is added after the recovery of the solution A (S104). However, the additive is added before that (for example, the acid exudate). Also good.

  Since the transition metals a, b,... Are mixed in S109, the solution is sequentially separated and recovered by filtering the solution after pH adjustment (S110, S111).

DESCRIPTION OF SYMBOLS 1 ... Dialysis membrane, 2 ... Dissolution inlet, 3 ... Dissolution outlet, 4 ... Recovery liquid inlet, 5 ... Recovery liquid outlet, 6 ... Addition for dialysis Pressure tank, 7 ... recovered liquid tank, 8 ... dialysis tank.

Claims (9)

In a metal recovery method for recovering a metal from a positive electrode material of a lithium ion battery containing lithium and a transition metal element,
An acid leaching step of dissolving the positive electrode material in an acidic solution and generating lithium ions and transition metal ions in the acidic solution;
An addition step of adding an additive that destroys the hydration structure to the acidic solution containing the lithium ion and the transition metal ion;
An acidic solution containing the lithium ions and the transition metal ions after adding an additive for removing the water of hydration, and a recovery solution are passed through an anion permeable membrane, and the lithium ions are removed from the acidic solution. A dialysis process for dialysis into the collected liquid;
A metal recovery method including a lithium recovery step of recovering the lithium ions from the dialyzed recovery liquid containing lithium ions. In claim 1,
The metal recovery method, wherein the additive removes hydration water of the lithium ion hydration structure. In claim 1 or 2,
After the acid leaching step, including a residue removal step of removing the residue of the positive electrode material,
The metal recovery method, wherein the addition step is performed after the residue removal step. In any one of Claims 1 thru | or 3,
The metal recovery method, wherein the additive contains DMI (1,3-dimethyl-2-imidazolidinone). In any one of Claims 1 thru | or 3,
The metal recovery method, wherein the additive contains a guanidate. In any one of Claims 1 thru | or 3,
The metal recovery method, wherein the additive is urea or a urea derivative. In claims 1 to 6,
The additive for destroying the hydration structure is a metal recovery method, wherein the difference between the mobility of cobalt ions and the mobility of lithium ions per concentration [M] is 2 or more in TLC. A dialysis accelerator added to a solution containing lithium ions and transition metal ions before dialysis,
A dialysis accelerator characterized by having a function of destroying a hydration structure of lithium ions. In claim 8,
The dialysis accelerator comprises any one of guanidine, DMI, urea, and urea derivatives.

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