JP4892925B2 - Method for recovering valuable metals from lithium-ion batteries - Google Patents

Description

  The present invention relates to a method of disassembling a battery and efficiently separating and recovering valuable metals such as lithium contained in a positive electrode active material in recycling a used lithium ion secondary battery.

  In response to the recent global warming trend, the effective use of electric power has been screamed. As one means, a secondary battery for power storage is expected, and from the standpoint of preventing air pollution, an early practical application of a large secondary battery is expected as a power source for automobiles. In addition, the demand for small secondary batteries has been increasing year by year with the spread of portable electric devices and the improvement in performance, particularly as backup power sources for computers and word processors, and power sources for small household appliances.

  As these secondary batteries, secondary batteries having a performance corresponding to the equipment to be used are required, but generally lithium ion batteries are mainly used. This lithium ion battery has a negative electrode material in which a negative electrode active material such as graphite is fixed to a negative electrode substrate made of copper foil in a metal outer can such as aluminum or iron, and lithium nickelate or cobalt on a positive electrode substrate made of aluminum foil. A positive electrode material to which a positive electrode active material such as lithium acid is fixed, a current collector made of aluminum or copper, a resin film separator such as a polypropylene porous film, and an electrolytic solution or an electrolyte are enclosed.

  In addition, in response to the growing demand for lithium ion batteries, there is a strong demand for establishment of environmental pollution countermeasures with used lithium ion batteries, and it has been studied to collect and effectively use valuable metals. As a method for recovering valuable metals from the lithium ion battery having the above-described structure, for example, dry processing or incineration processing as described in JP-A-07-207349 and JP-A-10-330855 is performed. There are many cases. However, these methods have drawbacks such as large consumption of heat energy and inability to recover lithium and aluminum. Further, when lithium hexafluorophosphate is contained as an electrolyte, there is a problem that the consumption of the furnace material is remarkable.

  On the other hand, even in the case of wet processing, dry processing is partially used as described in, for example, Japanese Patent Application Laid-Open Nos. 08-22846 and 2003-157913. For example, in the method described in Japanese Patent Application Laid-Open No. 08-22846, the active material is recovered by burning the positive electrode material, but there is a drawback that impurities may be mixed into the obtained active material. Further, in the method described in Japanese Patent Application Laid-Open No. 2003-157913, a dry process such as baking in a high-temperature oven is required in the electrolytic solution and electrolyte processing steps, and problems such as significant consumption of incinerator materials are pointed out. It was.

Japanese Patent Application Laid-Open No. 07-207349 JP-A-10-330855 Japanese Patent Laid-Open No. 08-022846 JP 2003-157913 A

  In view of such conventional circumstances, the present invention provides lithium, nickel, cobalt, etc. contained in a positive electrode active material, etc. without performing dry treatment such as heating and incineration in recycling of used lithium ion batteries. An object of the present invention is to provide a method for efficiently separating and recovering valuable metals.

  In order to achieve the above object, a valuable metal recovery method from a lithium ion battery provided by the present invention is a method of recovering a valuable metal from a lithium ion battery, a disassembly step of disassembling a lithium ion battery, and a battery disassembly A step of washing with an alcohol or water to remove the electrolytic solution and the electrolyte, a step of removing the positive electrode active material from the positive electrode substrate by immersing the washed battery disassembly in a sulfuric acid aqueous solution, and peeling A leaching step of leaching the positive electrode active material with an acidic solution in the presence of a fixed carbon-containing material, a neutralization step of separating and removing aluminum and copper by neutralization from the obtained leachate, nickel from the leachate after the neutralization step, A nickel / cobalt recovery process for separating and recovering cobalt, and the lithium in the remaining aqueous solution is concentrated by solvent extraction and back extraction, and then the lithium is solidified with lithium carbonate. Characterized in that it comprises a lithium recovery process of to separate and recover.

  In the above method for recovering valuable metals from a lithium ion battery according to the present invention, in the washing step, 10 to 300 g / l of a battery disassembled product is charged into alcohol or water and shaken or stirred. It is preferable that the washing operation is repeated a plurality of times after separating and adding new alcohol or water.

  In the method for recovering valuable metals from a lithium ion battery according to the present invention, the disassembled battery is immersed and stirred in a sulfuric acid aqueous solution having a pH of 0 to 3.0 in the positive electrode active material peeling step, so that the positive electrode active material is removed from the positive electrode substrate. The substance can be peeled off and separated and recovered as a solid.

  In the valuable metal recovery method from the lithium ion battery according to the present invention, the fixed carbon-containing material was selected from graphite, activated carbon, coal, coke, charcoal, and negative electrode powder recovered from the lithium ion battery in the leaching step. It is preferable to use at least one kind. Further, it is preferable that sulfuric acid is used as the acidic solution and the pH is maintained in the range of 0.5 to 1.5, and the fixed carbon-containing material is recovered and reused after the dissolution reaction.

  Further, in the method for recovering valuable metals from the lithium ion battery according to the present invention, in the neutralization step, the leachate of the positive electrode active material is adjusted to pH 3.0 to 5.5 with a neutralizing agent, and aluminum and copper are converted into starch. Can be separated and recovered. In the nickel / cobalt recovery step, the leachate after the neutralization step can be adjusted to pH 6.5 to 10.0 to separate and recover nickel and cobalt as starch.

  Furthermore, in the method for recovering valuable metals from a lithium ion battery according to the present invention, in the lithium recovery step, the aqueous solution remaining after the nickel / cobalt recovery step is adjusted to pH 4.0 or more and brought into contact with an acidic solvent extractant. After extracting lithium, the solvent extractant is brought into contact with an aqueous solution having a pH of 3.0 or lower to reversely extract lithium, and the resulting high-concentration lithium aqueous solution is mixed with a water-soluble carbonate while being kept at 60 ° C. or higher. Therefore, it is preferable to recover lithium as solid lithium carbonate.

  According to the present invention, after disassembling a used lithium ion battery, it is included in the positive electrode active material, etc., without performing a dry process such as heating and incineration, only by a wet process, and without using an expensive chemical. Valuable metals such as lithium, nickel and cobalt can be separated and recovered easily and efficiently.

A method for recovering valuable metals from a lithium ion battery according to the present invention will be described below with reference to the process chart shown in FIG.
(1) Disassembling process of lithium ion battery To recycle a used lithium ion battery, it is necessary to first disassemble the battery. In that case, since it is dangerous when the battery is charged, it is desirable to make it harmless by discharging the battery prior to disassembly. The harmless battery is disassembled to an appropriate size using a normal crusher or crusher. In addition, the outer can can be cut to separate and disassemble the positive electrode material, the negative electrode material, and the like inside, but in this case, it is desirable to further cut each separated part into an appropriate size.

(2) Washing step The battery disassembled product is washed with alcohol or water to remove the electrolytic solution and the electrolyte. The lithium ion battery contains an organic solvent such as ethylene carbonate, propylene carbonate, diethyl carbonate, and dimethyl carbonate, and an electrolyte such as lithium hexafluorophosphate. Therefore, by removing these in advance, it is possible to prevent organic components, phosphorus, fluorine, or the like from being mixed as impurities into the leachate in the subsequent peeling step.

  Alcohol or water is used for washing the battery disassembled material, and the battery disintegrated material is charged preferably at a rate of 10 to 300 g / l, and the organic components and the electrolyte are removed by shaking or stirring. As the alcohol, ethanol, methanol, and a mixed solution thereof are preferable. In general, carbonates are generally insoluble in water, but ethylene carbonate is arbitrarily soluble in water, and other organic components have some solubility in water, so they can be washed with water. If the amount of the battery disassembly with respect to alcohol or water is less than 10 g / l, it is not economical, and if it exceeds 300 g / l, the battery disassembly becomes bulky and difficult to clean.

  Cleaning the battery disassembly is not enough. Therefore, after the first cleaning is completed, it is preferable to separate the battery crushed material and alcohol or water, add new alcohol or water, and repeat the same cleaning operation a plurality of times. However, since it is not economical if the number of times of cleaning is too large, it is preferable to set it to 10 times or less. By this washing step, phosphorus, fluorine and the like derived from the organic component and the electrolyte can be removed to such an extent that they do not affect the subsequent step. For example, as the concentration in the leachate in the subsequent stripping step, the organic component can have a TOC (Total Organic Carbon) concentration of 0.1 g / l or less, and phosphorus and fluorine can also be 10 mg / l or less.

(3) Positive electrode active material peeling process The battery disassembled product after washing is then immersed in a sulfuric acid aqueous solution to peel and separate the positive electrode active material from the positive electrode substrate. That is, the positive electrode active material is fixed to the aluminum foil that is the positive electrode substrate even after the battery is disassembled. However, the positive electrode active material and the aluminum foil can be separated as they are in a solid state by being poured into an aqueous sulfuric acid solution and stirred. . This seems to be because the positive electrode active material is peeled off from the aluminum foil when the aluminum foil is eluted in a small amount. In this step, all the battery disassembled material may be immersed in the sulfuric acid aqueous solution, but only the positive electrode material portion may be selected from the battery disassembled material and immersed in the sulfuric acid aqueous solution.

  As the concentration of the sulfuric acid aqueous solution to be used, it is difficult to continuously control the sulfuric acid concentration to an appropriate value, so in practice it is simple and accurate to control the pH (hydrogen ion concentration) of the aqueous solution. In the present invention, the aqueous sulfuric acid solution is controlled to pH 0-3, preferably in the range of pH 1-2. When the pH of the aqueous sulfuric acid solution is less than 0, the sulfuric acid concentration is too high, so that both the aluminum foil and the positive electrode active material are eluted, making it difficult to separate them. On the other hand, if the pH exceeds 3, the concentration of sulfuric acid is too low, and the elution of the fixed portion does not proceed, and the positive electrode active material is not completely detached.

  Further, when a lithium ion battery is disassembled by crushing or the like, the positive electrode material and the negative electrode material are generally thin pieces. Therefore, although it may be put into the sulfuric acid aqueous solution as it is, depending on the method of disassembly, it is preferable to cut the length of one side into 30 mm square or less in advance for efficient separation. The input amount of the battery disassembled product with respect to the sulfuric acid aqueous solution is suitably 10 to 100 g / l. The time required for separating the positive electrode active material from the positive electrode substrate varies depending on the concentration of the sulfuric acid aqueous solution, the amount of the battery disassembly containing the positive electrode material, the size thereof, and the like, and thus it is preferable to determine in advance on a trial basis.

  The battery disassembled matter after the positive electrode active material peeling step is sieved to collect the positive electrode active material such as lithium nickelate and lithium cobaltate separated from the positive electrode substrate, and the accompanying materials. When all the battery disassembled materials are treated, the negative electrode powder such as graphite, which is a negative electrode active material, and those accompanying it are also collected. On the other hand, the parts of the positive and negative substrates, the outer can part made of aluminum or iron, the separator part made of a resin film such as a porous film of polypropylene, and the current collector part made of aluminum or copper are separated. Supply to each processing step.

(4) Leaching step In the next leaching step, the peeled and collected positive electrode active material is leached with an acidic solution in the presence of a fixed carbon-containing material. By adding the fixed carbon-containing material to the acidic solution, the leaching rate of nickel and cobalt from the positive electrode active material can be improved. Examples of the fixed carbon-containing material used include graphite (fixed carbon 95% or more), activated carbon (fixed carbon 90% or more), coal (fixed carbon 30 to 95%), coke (fixed carbon 75 to 85%), charcoal. (Fixed carbon of about 85%). Moreover, since the negative electrode powder recovered by this leaching step is mainly composed of graphite, it can be used, which is effective in terms of total recycling.

  The reason why the leaching rate of nickel and cobalt is improved by the coexistence of the fixed carbon-containing material is not clear, but the fixed carbon-containing material acts as an adsorbent of oxygen generated by the dissolution reaction, forming a reaction field. Alternatively, it is considered that the fixed carbon-containing material has a catalytic action of drawing lithium from the crystal structure of lithium nickelate or lithium cobaltate and destabilizing the structure. Therefore, in order to fully exhibit the leaching promotion effect, it is preferable to use a fixed carbon-containing material crushed into a powder.

  Although the amount of the above-mentioned fixed carbon-containing material is slightly different depending on the fixed carbon content, it is generally preferably about 50 to 300% by weight based on the weight of the positive electrode active material to be dissolved, and graphite having a high fixed carbon content. And in the case of negative electrode powder, about 50 to 100 weight% is preferable. If the amount of fixed carbon-containing material added is less than 50% by weight, the leaching rate of nickel or cobalt will be low, and if it exceeds 300% by weight, the amount of fixed carbon-containing material residue will increase, and it will adhere to the residue, thereby precious metal. This is not preferable because the loss amount increases and handling becomes worse. The fixed carbon-containing material can be recovered and reused after the dissolution reaction is completed.

  As the acidic solution used for dissolving the positive electrode active material, organic acids can be used in addition to mineral acids such as sulfuric acid, nitric acid and hydrochloric acid. However, in view of cost, work environment, and further recovery of nickel, cobalt, and the like from the leachate, it is preferable to use sulfuric acid industrially. In addition, the pH of the acidic solution to be used is preferably at least 2 or less, and more preferably controlled to about 0.5 to 1.5 in consideration of reactivity. Since the pH rises as the dissolution reaction of the positive electrode active material proceeds, it is preferable to add an acid such as sulfuric acid during the reaction to maintain the pH at about 0.5 to 1.5.

(5) Neutralization step The leachate obtained in the leaching step contains nickel, cobalt, lithium derived from the positive electrode active material, and a trace amount of aluminum, copper, etc. derived from the positive and negative substrates. In the neutralization step, the leachate is adjusted to pH 3.0 to 5.5 with a neutralizing agent, whereby aluminum and copper can be separated and recovered as starch. As the neutralizing agent, common chemicals such as soda ash, slaked lime, and sodium hydroxide can be used. These chemicals are inexpensive and easy to handle.

  As described above, the pH of the leachate is preferably adjusted to pH 3.0 to 5.5 by adding a neutralizing agent. If the pH of the leachate is less than 3.0, aluminum and copper cannot be separated and recovered as starch. . In addition, when the pH of the leachate is higher than 5.5, nickel and cobalt are simultaneously precipitated and contained in aluminum and copper starch, which is not preferable. Even when iron is contained in the leachate as another element, it can be separated into the starch simultaneously with aluminum and copper.

(6) Nickel / cobalt recovery process When nickel and cobalt are separated and recovered from the leachate that has been subjected to the above neutralization process, a neutralizing agent is further added to the leachate to adjust the pH to 6.5 to 10.0. To do. When the pH of the leachate is lower than 6.5, nickel and cobalt cannot be separated and recovered as starch. On the other hand, if the pH of the leachate exceeds 10.0, the amount of neutralizing agent used is increased, which is uneconomical. Also in this step, a general neutralizing agent such as soda ash, slaked lime, sodium hydroxide or the like can be used. In this step, lithium remains in the leachate.

  As a method for separating and purifying aluminum / copper, nickel / cobalt, and lithium, in addition to the above-described neutralization, methods such as sulfidation and solvent extraction are also conceivable. However, when sulfurization is used, copper and aluminum can be preferentially sulfurized and removed, but at the same time, the amount of nickel and cobalt lost increases. Moreover, since hydrogen sulfide gas is generated, a detoxification facility and a sulfide purification process are required. When solvent extraction is used, nickel and cobalt can be separated, but there is a problem that lithium is extracted simultaneously with nickel. It is also disadvantageous in that the equipment load for oil-water separation increases.

(7) Lithium recovery step In the lithium recovery step, first, the aqueous solution remaining after the nickel / cobalt recovery step is adjusted to pH 4.0 or higher, and brought into contact with the acidic solvent extractant. To extract. The acidic solvent extractant has hitherto been used only for extraction of light metals, but research by the present inventors has revealed that lithium can be extracted as the pH increases when the pH is 4 or more.

Examples of the acidic solvent extractant include 2-ethylhexylphosphonic acid mono-2-ethylhexyl (pH 4 to 7), di (2-ethylhexyl) phosphonic acid (pH 4 to 6), and bis (2,4,4-trimethylpentyl). ) Phosphonic acid (pH 4-8) or a mixture of phenylalkyl beta diketone and trioctyl phosphonic acid (pH 4-10). In addition, the pH value described at the end of each solvent extractant is a pH value suitable for extraction of lithium ions.

  In addition, when other metals (for example, nickel, iron, etc.) extracted to the acidic solvent extractant in the adjusted pH range are present as ions in the aqueous solution, other metals are also extracted to the solvent extractant side together with lithium. In the subsequent back extraction, it is back extracted to the aqueous solution side and concentrated in the same manner as lithium. Therefore, it is desirable to separate and remove these other metal ions by a neutralization operation or the like before performing an extraction operation with an acidic solvent extractant for concentration of lithium.

Next, the acidic solvent extractant from which lithium has been extracted is brought into contact with an aqueous solution adjusted to a pH of 3.0 or lower, so that lithium is dissolved in an aqueous solution at a concentration higher than the concentration (several g / l) of the initially extracted lithium aqueous solution. Can be back-extracted. This is because, as a characteristic of the acidic solvent extractant, the extracted metal ions have a property of releasing metal ions by ion exchange with H ⁺ by bringing the pH to the acidic side.

  Preferably, this aqueous solution on the back-extraction side is used repeatedly, and the above-described extraction and back-extraction operations are repeated a plurality of times, so that the lithium concentration in the aqueous solution is sufficient to be solid lithium carbonate by carbonation. Concentrate to a level of about g / l. In addition, the extraction rate and the back extraction rate can be controlled by accurately controlling the pH, and therefore the final adjustment of the lithium concentration can be controlled.

  The concentrated aqueous lithium solution thus concentrated can then be mixed and stirred with a water-soluble carbonate such as sodium carbonate to precipitate lithium in the aqueous solution as solid lithium carbonate. However, lithium carbonate, which is a lithium carbonate, differs in solubility from other salts, and its solubility rapidly decreases as the aqueous solution temperature increases. That is, the solubility of lithium carbonate is 1.28 g / l at 25 ° C., but decreases to 1.00 g / l at 60 ° C., and decreases to 0.7 g / l at 100 ° C.

  Therefore, when the temperature of the high-concentration lithium aqueous solution is increased to 60 ° C. or higher, the solubility becomes lower than other salts such as sodium sulfate having a high solubility, and lithium carbonate is selectively precipitated as crystals, so that high purity lithium carbonate A solid can be obtained. The temperature of the high-concentration lithium aqueous solution should be high, but in general, if it is 80 ° C or higher, the operation becomes difficult and the cost increases from the viewpoint of the heat resistance temperature of the reaction vessel and peripheral devices, and if it is 90 ° C or higher, the boiling point is increased. In general, 60 to 80 ° C. can be said to be an appropriate temperature range.

[Disassembly and cleaning process of lithium-ion battery]
The lithium-ion battery was disassembled into a size of 1 to 3 cm ^{2 using} a biaxial crusher. 10 g of this battery disassembled product was put in a 500 ml container, put in 100 ml of 99% or more ethanol and sealed, rotated for 60 minutes at 200 rpm using a ball mill rotary table, and washed with stirring. After stirring and washing with ethanol, the battery disassembled product and ethanol were separated by filtration.

[Washing process]
100 ml of ethanol was again mixed with the disassembled battery after filtration, and the same procedure as above was repeated to perform stirring and washing with ethanol. That is, this stirring and washing was repeated three times, and phosphorus (P) and fluorine (F) were analyzed for each ethanol washing solution. As a result, P concentration and F concentration were P: 600 mg / l and F: 120 mg / l for the first ethanol washing solution, P: 48 mg / l and F: 11 mg / l for the second ethanol washing solution, and P for the third ethanol washing solution. : 10 mg / l or less and F: 10 mg / l or less.

  Furthermore, in order to confirm whether the battery disassembled material after the third ethanol washing was sufficiently washed, the battery disassembled material was once dried to remove ethanol, and then the P and F concentrations in the leachate leached with sulfuric acid, organic components The (TOP) concentration was measured. As a result, the P concentration was 10 mg / l or less, the F concentration was 10 mg / l or less, and the TOP concentration was 0.1 g / l or less. From this result, it was found that the battery dismantled product was sufficiently washed by washing with ethanol three times.

  Instead of stirring and washing with ethanol as described above, stirring and washing with water was performed three times in the same manner as described above. The analysis results of P and F for each water washing solution are as follows: P: 550 mg / l and F: 100 mg / l for the first water washing solution, P: 64 mg / l and F: 10 mg / l for the second water washing solution, and 3rd time In the water washing solution, P was 10 mg / l or less and F: 10 mg / l or less.

  Further, in order to confirm whether or not the battery disassembled material after the third water washing was sufficiently washed, the respective concentrations of P, F, and TOP in the leachate obtained by leaching the battery disassembled material with sulfuric acid were measured. As a result, the P concentration was 10 mg / l or less, the F concentration was 10 mg / l or less, and the TOP concentration was 0.05 g / l. From this result, it was found that the battery dismantled product was sufficiently washed even by washing with water three times.

[Positive electrode active material peeling process]
A portion of the positive electrode material is selected from the battery disassembled product after the stirring and washing step with ethanol described above, put into a container containing a sulfuric acid aqueous solution, and diluted sulfuric acid is dropped to adjust the pH to a range of 1.5 to 2.0. Stirring while adjusting. Stirring was performed at room temperature, and the aqueous sulfuric acid solution after the reaction was filtered, and the state of the residue was observed.

  As a result, when the input amount of the positive electrode material portion was 20 g / l, it was confirmed that almost all of the positive electrode active material fixed to the positive electrode substrate surface of the aluminum foil was peeled off by stirring for about 30 minutes. The concentration of aluminum dissolved in the aqueous solution was measured to be about 0.1 g / l. On the other hand, the aluminum foil in the charged positive electrode material portion was about 3 g, so the aluminum foil as the positive electrode substrate was about 1. Only 7% by weight of elution was observed.

  When the amount of the positive electrode material portion was changed and the same peeling treatment was performed as above, when the amount of input was about 100 g / l, not only the stirring of the liquid became difficult, but also the time required for peeling increased. The peeling situation also decreased. On the contrary, when the input amount is as small as about 10 g / l, the time required for stripping is shortened, but the stripping efficiency is lowered, for example, the amount of sulfuric acid used is relatively increased. From these results, it was found that the input amount of the positive electrode material portion is preferably in the range of 10 to 100 g / l.

[Leaching process]
The positive electrode active material (LiNi _0.85 Co _0.15 O ₂ ) recovered in the positive electrode active material peeling step (5.0 g) and the negative electrode powder (fixed carbon 95) recovered from the negative electrode material portion in the battery disassembled after the cleaning step. %) 4.0 g was put into 50 ml of sulfuric acid acidic solution having a pH of 1.0. The sulfuric acid acidic solution was heated at 80 ° C. for 4 hours, during which time 64% sulfuric acid was gradually added to maintain the pH of the solution at about 1.0.

  The solution after completion of the reaction was filtered using a 0.45 μm membrane filter, and nickel (Ni), cobalt (Co) and lithium (Li) in the filtrate and the residue were analyzed with an ICP emission spectrophotometer. The leaching rate of cobalt was calculated. As a result, 90% Ni, 90% Co, and 100% lithium were leached. The weight of the leaching residue was 4.0 g, and the added negative electrode powder was not consumed and could be reused.

[Neutralization process]
A 100 g / l soda ash (Na ₂ CO ₃ ) solution was added as a neutralizer under a reaction temperature of 60 ° C. while stirring the leachate obtained in the leaching step with a Teflon impeller having a rotation speed of 200 rpm. . At that time, the pH of the leachate is adjusted to 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 to separate and remove aluminum (Al) and copper (Cu). It was. In addition, the said leaching solution has a composition of Ni: 20.0 g / l, Co: 3.4 g / l, Li: 3.2 g / l, Al: 2.72 g / l, Cu: 0.50 g / l. Using.

  After completion of the reaction, the leachate was filtered, and the concentrations of Ni, Co, Li, Al, and Cu in the filtrate were measured. The results obtained are shown in FIG. Each element was analyzed by atomic absorption for Li and ICP for the others. Al began to be removed as starch from around pH 3.0, and was removed to an Al concentration of 0.1 g / l or less near pH 4.5. Cu began to be removed as a starch from around pH 4.0, and was removed to a Cu concentration of 0.1 g / l or less around pH 5.0. From this result, it is possible to efficiently separate and remove Al and Cu while suppressing loss of Ni, Co and Li by adjusting the pH to preferably 3.0 to 5.5, more preferably 4.5 to 5.0. I can see that

[Nickel / cobalt recovery process]
A 100 g / l soda ash (Na ₂ CO ₃ ) solution as a neutralizing agent was added as a neutralizing agent while stirring the leachate after completion of the neutralization step with a Teflon impeller having a rotation speed of 200 rpm under a reaction temperature of 60 ° C. Added. At that time, the pH of the leachate was adjusted to 5.5, 6.0, 6.5, 7.0, 7.5, and 8.0, respectively, and Ni and Co were separated and recovered. The leachate used had a composition of Ni: 13.9 g / l, Co: 2.4 g / l, Li: 1.3 g / l.

  After completion of the reaction, the leachate was filtered, and the concentrations of Ni, Co, and Li in the filtrate were measured in the same manner as in the neutralization step. The results obtained are shown in FIG. Ni began to be removed as a starch from around pH 6.5, and was separated to a concentration of 0.1 g / l or less around pH 8.0. Co began to be removed as a starch from around pH 6.5, and was separated to a concentration of 0.1 g / l or less around pH 8.0. Ni and Co can be separated even at a pH of 10.0 or higher, but this is not appropriate in view of the consumption of the neutralizing agent. Therefore, it can be seen that the pH for separating and recovering Ni and Co is preferably 6.5 to 10.0, and more preferably 7.5 to 8.0.

[Lithium recovery process]
Using an aqueous solution having a Li concentration of 5 g / l after completion of the nickel / cobalt recovery step, an acidic solvent extractant is added so that the volume ratio of the aqueous solution to the extractant is 1: 2, and a 5 wt% NaOH solution is further added. Was added dropwise and lithium was extracted by contact mixing while adjusting the pH of the mixed aqueous solution to 7.0. As the acidic solvent extractant, 2-ethylhexylphosphonic acid mono-2-ethylhexyl (manufactured by Daihachi Chemical Co., Ltd., trade name PC-88A) 20% by volume + diluent (manufactured by Shin Nippon Oil Co., Ltd., product) Name: Tecrine N20) 80% by volume was used. As a result, the lithium concentration in the extractant after completion of the extraction was 1.5 g / l.

  Next, the extractant from which lithium has been extracted is contact-mixed with pure water so that the volume ratio of pure water to the extractant is 1: 2, and the aqueous solution after mixing has a pH of 0.1. Lithium was back-extracted by dropwise addition of a weight% aqueous sulfuric acid solution. The aqueous lithium solution remaining after the first back extraction operation was contact-mixed again with an extractant containing lithium, and the back extraction operation was repeated 5 times. When the lithium concentration of the remaining aqueous lithium solution was measured after 5 back extraction operations, it was concentrated to a concentration of 17.3 g / l.

  The temperature of this concentrated lithium aqueous solution was adjusted to 60 ° C., and a sodium carbonate aqueous solution having a concentration of 200 g / l was dropped and mixed to precipitate lithium carbonate as crystals. The sulfur grade in the obtained lithium carbonate was as low as 0.05% by weight, and pure lithium carbonate could be recovered.

It is process drawing which shows the collection | recovery method of the valuable metal from the lithium ion battery by this invention. It is a graph which shows the relationship between pH in the neutralization process of this invention method, and the density | concentration of Ni, Co, Li, Al, and Cu in a filtrate. It is a graph which shows the relationship between pH in the nickel * cobalt recovery process of this invention method, and the density | concentration of Ni, Co, and Li in a filtrate.

Claims (8)

A method for recovering valuable metals from a lithium ion battery, comprising: a disassembly process for disassembling the lithium ion battery; a cleaning process for removing the electrolytic solution and the electrolyte by washing the disassembled battery with alcohol or water; A positive electrode active material peeling step of detaching the positive electrode active material from the positive electrode substrate, and a leaching step of leaching the peeled positive electrode active material with an acidic solution in the presence of a fixed carbon-containing material. Neutralization step of separating and removing aluminum and copper from the leachate by neutralization, and adjusting the pH of the leachate after the neutralization step to 6.5 to 10.0 to separate and recover nickel and cobalt as starch A recovery step and a lithium recovery step of concentrating lithium in the remaining aqueous solution by solvent extraction and back extraction, and separating and recovering lithium as a lithium carbonate solid. Valuable metal recovery process from a lithium ion battery according to claim.   In the washing step, 10 to 300 g / l of battery disassembled material is added to alcohol or water and shaken or stirred, then the battery disassembled material and alcohol or water are separated, and further the above-described washing operation is performed by adding new alcohol or water. The method for recovering valuable metals from a lithium ion battery according to claim 1, wherein the method is repeated a plurality of times.   In the positive electrode active material peeling step, the battery disassembly is immersed and stirred in a sulfuric acid aqueous solution having a pH of 0 to 3.0, whereby the positive electrode active material is peeled from the positive electrode substrate and separated and recovered as a solid, A method for recovering valuable metals from a lithium ion battery according to claim 1 or 2.   In the leaching step, at least one selected from graphite, activated carbon, coal, coke, charcoal, and negative electrode powder recovered from a lithium ion battery is used as the fixed carbon-containing material. 4. A method for recovering valuable metals from a lithium ion battery according to any one of 3 above.   The sulfuric acid is used as the acidic solution and the pH is maintained in the range of 0.5 to 1.5, and the fixed carbon-containing material is recovered and reused after the dissolution reaction. The valuable metal recovery method from the lithium ion battery as described in 2.   In the neutralization step, the leachate of the positive electrode active material is adjusted to pH 3.0 to 5.5 with a neutralizing agent, and aluminum and copper are separated and recovered as a starch. A method for recovering valuable metals from a lithium ion battery according to any one of the above. In the lithium recovery step, the aqueous solution remaining after the nickel / cobalt recovery step is adjusted to pH 4.0 or more, contacted with an acidic solvent extractant to extract lithium, and then the solvent extractant is adjusted to pH 3.0 or less. It is characterized by recovering lithium as solid lithium carbonate by bringing lithium into contact with an aqueous solution and back-extracting lithium, and mixing the obtained high-concentration lithium aqueous solution with a water-soluble carbonate in a state kept at 60 ° C. or higher. A method for recovering a valuable metal from a lithium ion battery according to any one of claims 1 to 6 . Examples of the acidic solvent extractant include mono-2-ethylhexyl 2-ethylhexylphosphonate, di (2-ethylhexyl) phosphonic acid, bis (2,4,4-trimethylpentyl) phosphonic acid, phenylalkyl beta diketone and trioctylphosphone. The method for recovering valuable metals from a lithium ion battery according to claim 7 , wherein any one selected from a mixture of acids is used.

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