JP5577926B2 - Method for leaching nickel and cobalt, and method for recovering valuable metals from lithium ion batteries - Google Patents

Description

  The present invention relates to a method for leaching nickel and cobalt, and a method for recovering valuable metals from lithium ion batteries, and in particular, when leaching a positive electrode active material contained in a lithium ion battery, the compound constituting the positive electrode active material is effective. The present invention relates to a nickel and cobalt leaching method that can be decomposed to improve the leaching rate and a valuable metal recovery method to which the leaching method is applied.

  In response to the recent global warming trend, effective use of electric power is required. As one of the 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 continues to increase year by year, especially as a backup power source for computers and power supplies for small household electrical appliances, especially with the widespread use and improvement in performance of electrical devices such as digital cameras and mobile phones. It is in.

  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 includes 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 separator made of a resin film such as a porous film of polypropylene, and an electrolytic solution or an electrolyte are enclosed.

  By the way, in response to the growing demand for lithium ion batteries, establishment of countermeasures against environmental pollution by used lithium ion batteries is strongly demanded, and it is considered 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 Patent Documents 1 and 2 is used. However, these methods have drawbacks such as large consumption of heat energy and inability to recover lithium (Li) and aluminum (Al). Further, when lithium hexafluorophosphate (LiPF ₆ ) is contained as an electrolyte, there is a problem that the consumption of the furnace material is remarkable.

  As described in Patent Documents 3 and 4, a method for recovering valuable metals by wet processing has been proposed for the problem of such dry processing or incineration processing.

Here, in a method for recovering valuable metals by wet processing of a lithium ion battery, leaching the positive electrode active material containing valuable metals from a solid state to a liquid state, that is, a metal ion state is one of the main chemical treatments. It becomes. In this leaching treatment, in order to efficiently recover valuable metals such as nickel (Ni) and cobalt (Co), compounds such as LiCoO ₂ and LiNiO ₂ that are compounds constituting the positive electrode active material are effectively used. It is necessary to disassemble. Conventionally, in this treatment, negative electrode powder as an oxygen adsorbent is added to the acidic solution.

  However, the negative electrode powder is weak in reducing power in a discharged state, cannot be effectively and rapidly decomposed, and nickel and cobalt cannot be sufficiently leached from the positive electrode active material. The recovery rate could not be improved.

Japanese Patent Application Laid-Open No. 07-207349 JP-A-10-330855 Japanese Patent Laid-Open No. 08-22846 JP 2003-157913 A

Therefore, the present invention has been proposed in view of such circumstances, and can effectively decompose compounds such as LiCoO ₂ and LiNiO ₂ that are positive electrode active materials, and nickel and cobalt from the positive electrode active materials. An object of the present invention is to provide a nickel and cobalt leaching method capable of improving the recovery rate of valuable metals by improving the leaching rate of lithium and a method of recovering valuable metals from lithium ion batteries using the leaching method.

As a result of intensive studies to achieve the above object, the present inventors have obtained a positive electrode active material by adding a metal having a high reducing effect when leaching the positive electrode active material peeled and recovered from the lithium ion battery. It has been found that compounds such as LiCoO ₂ and LiNiO ₂ can be effectively decomposed and the leaching rate of nickel and cobalt from the positive electrode active material can be improved, and the present invention has been completed.

That is, the present invention is a method of leaching nickel and cobalt in which an nickel and cobalt contained in a positive electrode active material of a lithium ion battery are leached into an acidic solution, the porous solution obtained from a nickel-hydrogen battery in the acidic solution. It is characterized in that nickel and cobalt are leached from the positive electrode active material by adding a quality nickel plate or reduced roasted powder .

The present invention also relates to a valuable metal recovery method for recovering valuable metals from a lithium ion battery, wherein the positive electrode active material peeled from the lithium ion battery is treated with a porous nickel plate obtained from a nickel-hydrogen battery or a reduced roasting plate. It is characterized by including a leaching step in which nickel and cobalt are leached from the positive electrode active material by immersing in an acidic solution to which calcined powder is added.

Here, the addition amount of the porous nickel plate or reduced roasted powder obtained from the nickel-hydrogen battery is 0.5 to 2.0 times the mole of the positive electrode active material to be dissolved. preferable.

  According to the present invention, in the leaching treatment, the compound constituting the positive electrode active material can be effectively decomposed, the leaching rate of nickel and cobalt from the positive electrode active material can be improved, and the recovery rate of valuable metals can be improved. Can be improved.

It is a figure which shows the process of the collection | recovery method of the valuable metal from a lithium ion battery. It is a graph which shows transition of the cobalt density | concentration in the reaction solution with respect to the addition amount of sulfidizing agents when changing pH at the time of a sulfidation reaction. Is a graph showing changes in the concentrations of nickel and cobalt to the addition amount of sulfurizing agent to be added in the sulfurization reaction (Na 2 _S).

  Hereinafter, a method for leaching nickel and cobalt according to the present invention and a method for recovering valuable metals from a lithium ion battery to which the leaching method is applied will be described in detail in the following order with reference to the drawings.

1. 1. Outline of the present invention 2. Recovery method of valuable metals from lithium ion batteries Other Embodiments 4. Example

<1. Summary of the present invention>
The present invention relates to a method for leaching nickel (Ni) and cobalt (Co) and a method for recovering valuable metals from a lithium ion battery to which the leaching method is applied. In the leaching, the compound constituting the positive electrode active material is effectively decomposed to improve the leaching rate of nickel and cobalt from the positive electrode active material, thereby improving the recovery rate of valuable metals.

In a method for recovering valuable metals from a lithium ion battery, leaching a positive electrode active material containing valuable metals from a solid state to a liquid state, that is, a metal ion state is one of the main chemical treatments. Conventionally, in this leaching treatment, an acidic solution such as sulfuric acid is used, and it is necessary to decompose a compound such as LiCoO ₂ or LiNiO ₂ that is a positive electrode active material. Therefore, negative electrode powder or the like is added as an oxygen adsorbent. It was. However, the additive, such as negative electrode powder, has a weak reducing power in a discharged state, and cannot effectively and quickly decompose the compound constituting the positive electrode active material. The leaching rate of nickel and cobalt could not be increased.

Therefore, the present invention adds a metal having a high reduction effect, that is, a metal having a lower reduction potential than the reduction potential of hydrogen, when the positive electrode active material peeled and collected from the positive foil is leached with an acidic solution. With such a high reducing power, compounds such as LiCoO ₂ and LiNiO ₂ contained in the positive electrode active material are effectively and rapidly decomposed to improve the leaching rate of nickel and cobalt from the positive electrode active material.

  In the present invention, metals such as nickel (Ni), iron (Fe), zinc (Zn), and aluminum (Al) can be used as the metal added in the leaching treatment. Among them, it is particularly preferable to use nickel metal (porous nickel plate, reduced roasted powder) recovered from a nickel-hydrogen (Ni-MH) battery. By using nickel metal recovered from the nickel-hydrogen battery, contamination can be reduced by utilizing the metal part of the same recyclable nickel-hydrogen battery without separately preparing a new reducing agent other than the battery material. The positive electrode active material containing a valuable metal can be effectively decomposed without causing it to occur and without impairing economy.

  Hereinafter, an embodiment relating to a method for recovering valuable metals from a lithium ion battery to which the present invention is applied (hereinafter referred to as “this embodiment”) was recovered from a nickel-hydrogen battery as a metal having a high reduction effect. The case where nickel metal is used will be described in more detail as a specific example.

<2. Method for recovering valuable metals from lithium-ion batteries>
First, a method for recovering valuable metals from a lithium ion battery according to the present embodiment will be described below with reference to the process chart shown in FIG. As shown in FIG. 1, the valuable metal recovery method includes crushing / disintegrating step S1, cleaning step S2, positive electrode active material peeling step S3, leaching step S4, rare earth element removing step S5, and neutralizing step. S6 and sulfidation step S7. Note that the method of recovering valuable metals from the lithium ion battery is not limited to these steps, and can be changed as appropriate.

(1) Crushing / disintegrating step In the crushing / disintegrating step S1, in order to recover valuable metals from the used lithium ion battery, the battery is disassembled by crushing / disintegrating. At that time, since the battery is dangerous in a charged state, it is preferable to make the battery harmless by discharging the battery prior to disassembly.

  In the crushing / disintegrating step S1, the harmless battery is disassembled into an appropriate size using a normal crusher or a 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 preferable to further cut each separated part into an appropriate size.

(2) Washing step In the washing step S2, the battery disassembled material obtained through the crushing / disintegrating step S1 is washed with alcohol or water to remove the electrolyte and the electrolyte. The lithium ion battery includes an organic solvent such as ethylene carbonate, propylene carbonate, diethyl carbonate, and dimethyl carbonate, and an electrolyte such as lithium hexafluorophosphate (LiPF ₆ ). Therefore, by removing these in advance, it is possible to prevent organic components, phosphorus (P), fluorine (F), and the like from being mixed as impurities in the leachate in the positive electrode active material peeling step S3 described later.

  Alcohol or water is used for washing the battery disassembled material, and the battery disassembled material is charged at a rate of preferably 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. Further, the amount of the battery disassembled product with respect to alcohol or water is not economical if it is less than 10 g / l, and if it exceeds 300 g / l, the battery disassembled product is bulky and difficult to clean.

  It is preferable to repeatedly clean the battery disassembled product a plurality of times. By this washing step S2, phosphorus, fluorine and the like derived from the organic components and the electrolyte can be removed to the extent that they do not affect the subsequent steps.

(3) Positive electrode active material peeling step In the positive electrode active material peeling step S3, the battery disassembled material obtained through the cleaning step S2 is immersed in an acidic solution such as an aqueous sulfuric acid solution or a surfactant solution, thereby removing the battery from the positive electrode substrate. The positive electrode active material is peeled and separated. Even after the battery is disassembled, the positive electrode active material is fixed to the aluminum foil as the positive electrode substrate. In this positive electrode active material peeling step S3, the battery disassembled material is charged into an acidic solution such as an aqueous sulfuric acid solution or a surfactant solution and stirred. As a result, the positive electrode active material and the aluminum foil can be separated while remaining solid.

  In particular, it is preferable to peel off the positive electrode active material by immersing the battery disassembled material in a surfactant solution and mechanically stirring it. Thereby, it can suppress that the valuable metal contained in a positive electrode active material elutes in a solution, and can eliminate the recovery loss of valuable metal.

  In this positive electrode active material peeling step S3, the entire battery disassembled product may be immersed in a sulfuric acid aqueous solution or a surfactant solution, but only the positive electrode material portion may be selected and immersed from the battery disassembled product.

  When an aqueous sulfuric acid solution is used as the acidic solution, the pH of the acidic solution is controlled in the range of pH 0 to 3, preferably pH 1 to 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.

  The input amount of the battery disassembled product with respect to the sulfuric acid aqueous solution is suitably 10 to 100 g / l. In addition, when the lithium ion battery is disassembled by crushing or the like, the positive electrode material and the negative electrode material are generally thin pieces, and thus may be put into the sulfuric acid aqueous solution as it is. It is preferable to cut to 30 mm square or less. Thereby, efficient separation can be performed.

  Moreover, when using surfactant, it does not specifically limit as the kind of surfactant to be used, Nonionic surfactant, anionic surfactant, etc. can be used, These are single 1 type or 2 More than one species can be used in combination. Specifically, examples of the nonionic surfactant include polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl ether, and the like. Further, as anionic surfactants, alkyl diphenyl ether disulfonate and its salt, bisnaphthalene sulfonate and its salt, polyoxyalkylsulfosuccinate and its salt, polyoxyethylene phenyl ether sulfate and its salt , Etc. Among these, a nonionic surfactant having a polyoxyalkylene ether group can be particularly preferably used.

  The addition amount of the surfactant is preferably 1.5% by weight to 10% by weight. By making the addition amount 1.5% by weight or more, the positive electrode active material can be peeled and collected so as to obtain a high recovery rate. Moreover, by making the addition amount 10% by weight or less, the positive electrode active material can be efficiently peeled without economical loss. Further, the pH of the surfactant solution is neutral.

  Note that the separation time of the positive electrode active material in the positive electrode active material peeling step S3 varies depending on the concentration of the sulfuric acid aqueous solution and the surfactant solution, the input amount and the size of the battery dismantled material including the positive electrode material, and the like. It is preferable to keep it.

  The battery disassembled material 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 the negative electrode active material, and those accompanying it are also collected. On the other hand, the part of the positive electrode substrate and the negative electrode substrate, the outer can part made of aluminum or iron, the separator part made of a resin film such as a porous film of polypropylene, the current collector part made of aluminum or copper (Cu), etc. Separated and supplied to each processing step.

(4) Leaching step In the leaching step S4, metal ions such as nickel and cobalt are leached from the peeled and collected positive electrode active material using an acidic solution to form a slurry. In the valuable metal recovery method according to the present embodiment, in the leaching step S4, a metal having a high reducing effect, that is, a metal having a lower potential than hydrogen is added.

In the present embodiment, by adding a metal having a high reducing effect and leaching out the positive electrode active material in this way, the high reducing power of the metal causes LiCoO ₂ , LiNiO _2, etc. contained in the positive electrode active material. The compound can be effectively and quickly decomposed into metal ions, and the leaching rate of valuable metals such as nickel and cobalt in the positive electrode active material can be improved.

  In the present embodiment, nickel metal (porous nickel plate, reduced roasted powder) recovered from a nickel-hydrogen battery is used as the metal having a high reduction effect. Thus, by using nickel metal recovered from the nickel-hydrogen battery, a reagent for decomposing the positive electrode active material can be saved without separately preparing a new reducing agent other than the battery material. In addition, by utilizing the metal part of the nickel-hydrogen battery, which is the same battery to be recycled, the valuable metal-containing compound can be efficiently decomposed without causing contamination and without impairing the economy. Can do.

  The addition amount of nickel metal recovered from the nickel-hydrogen battery is preferably 0.5 to 2.0 times the mole of the positive electrode active material to be dissolved. Further, it is preferable to adjust by adding nickel metal or blowing air or oxygen so that the oxidation-reduction potential (ORP) (reference electrode: silver / silver chloride electrode) is in the range of −100 to 550 mV. By adding nickel metal while adjusting the range of the ORP value, nickel metal can be effectively dissolved.

  In the leaching step S4, as the acidic solution used for dissolving the positive electrode active material, an organic acid or the like can be used in addition to a mineral acid such as sulfuric acid, nitric acid, and hydrochloric acid. Among them, it is preferable to use a sulfuric acid solution industrially from the viewpoint of cost, work environment, and recovery of nickel, cobalt, and the like from the leachate.

  Further, the pH of the acidic solution to be used is preferably at most 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) Rare earth element removing step In the rare earth element removing step S5, the rare earth element (RE) is removed by precipitation from the leachate obtained in the leaching step S4.

  The nickel metal recovered from the nickel-hydrogen battery added in the leaching step S4 contains rare earth elements such as lanthanum (La), cerium (Ce), neodymium (Nd), and is added in the leaching step S4. These rare earth elements are contained in the leachate. When rare earth elements recover valuable metals such as nickel and cobalt as sulfides in the sulfidation step S7 described later, there is a possibility that precipitates are formed together with nickel and cobalt to impair the quality of nickel / cobalt sulfides. is there. Therefore, in the present embodiment, in the rare earth element removing step S5, a process for precipitating and removing rare earth elements from the leachate is performed. Thereby, rare earth elements can be effectively removed from the leachate, and valuable metals with high purity can be efficiently recovered.

Specifically, in the rare earth element removing step S5, an alkaline sulfate such as sodium sulfate as a rare earth element is added to the leachate to make the rare earth element a hardly soluble sulfate double salt. The following formula (1) shows a reaction for forming a rare-earth element sparingly soluble double salt. In the formula, RE represents a rare earth element.
RE ₂ (SO ₄ ) ₃ + Na ₂ SO ₄ + xH ₂ O
_{⇒ RE 2 (SO 4) 3} · Na 2 SO 4 · xH 2 O (1)

  The alkali sulfate as a rare earth agent to be added is added in the form of crystals or an aqueous solution and mixed with the leachate. Moreover, it is preferable to make it the addition amount into 10 times mole or more of the derare earth element contained in a leaching solution.

  Moreover, it is preferable to set it as 0-4 as pH in the production | generation reaction of this hardly soluble double salt of rare earth elements. The formation reaction of the rare-earth element poorly soluble double salt only needs to be saturated with alkali sulfate in the liquid, and the reaction occurs without influence when the pH is low. On the other hand, when the pH is too high, valuable metals such as nickel and cobalt form precipitates as hydroxides, resulting in a recovery loss of valuable metals.

  Moreover, as reaction temperature, it is preferable to set it as 60-80 degreeC. When the reaction temperature is lower than 60 ° C., there is a possibility that a rare-earth element hardly soluble double salt cannot be effectively produced with respect to a predetermined amount of alkali sulfate. On the other hand, if the reaction temperature is too high, the cost for raising the temperature is high and it is not efficient.

  In this way, in the rare earth element removal step S5, a rare earth element sulfate double salt precipitate (de-reacted RE) is formed without precipitating valuable metals to be recovered, such as nickel, cobalt, and lithium. The rare earth elements are separated and recovered by filtration. The solution (de-resolved final solution) obtained through the rare earth element removal step S5 is then sent to the neutralization step S6.

(6) Neutralization Step In the neutralization step S6, the filtrate from which the rare earth elements have been removed through the rare earth element removal step S5 (de-resolved final solution) is neutralized with a neutralizing agent, and a trace amount derived from the positive and negative substrates. Aluminum and copper are separated and recovered as precipitates.

  As the neutralizing agent, general chemicals such as soda ash, slaked lime, and sodium hydroxide can be used, and these chemicals are inexpensive and easy to handle.

  The pH of the solution is preferably adjusted to pH 3.0 to 5.5 by adding the neutralizing agent described above. If the pH is less than 3.0, aluminum and copper cannot be separated and recovered as starch. On the other hand, when the pH is higher than 5.5, nickel and cobalt are precipitated at the same time, and are contained in the aluminum and copper starch, resulting in loss. Even when iron is contained in the solution as another element, it can be separated into the starch simultaneously with aluminum and copper.

(7) Sulfurization step In the sulfidation step S7, the solution obtained through the neutralization step S6 is introduced into a reaction vessel, and a sulfurization reaction is caused by adding a sulfiding agent to produce a nickel / cobalt mixed sulfide. Thus, nickel and cobalt, which are valuable metals, are recovered from the lithium ion battery. As the sulfiding agent, alkali sulfides such as sodium sulfide and sodium hydrosulfide can be used.

Specifically, in this sulfidation step S7, nickel ions (or cobalt ions) contained in the solution become sulfides by a sulfidation reaction with an alkali sulfide according to the following formula (2) or (3).
Ni ²⁺ + NaHS ⇒ NiS + H ⁺ + Na ⁺ (2)
Ni ²⁺ + Na ₂ S ⇒ NiS + 2Na ⁺ (3)

  As the addition amount of the sulfiding agent in the sulfiding step S7, for example, it is added so as to be 1.0 to 1.5 equivalents with respect to the contents of nickel and cobalt in the solution. However, in operation, it may be difficult to accurately and rapidly analyze the concentration of nickel and cobalt in the leachate, and even if a sulfurizing agent is further added, the fluctuation of the ORP in the reaction solution is eliminated. More preferably, the sulfurizing agent is added up to that point. For example, when sodium sulfide is added as a sulfiding agent, the ORP value of the saturated sodium sulfide solution is about −400 mV, and therefore it is preferable to add based on the ORP value. Thereby, nickel and cobalt leached into the solution can be surely sulfided, and these valuable metals can be recovered at a high recovery rate.

  Further, the temperature of the sulfurization reaction in the sulfurization step S7 is not particularly limited, but is preferably 70 to 95 ° C, more preferably about 80 ° C. If the temperature of the sulfidation reaction is less than 70 ° C., the sulfidation reaction rate becomes slow and the reaction time becomes longer. On the other hand, if the temperature is higher than 95 ° C., the cost is increased to increase the temperature. There are many.

  Here, in the present embodiment, as described above, the nickel metal recovered from the nickel-hydrogen battery in the leaching step S4 is added. Therefore, the leachate contains rare earth elements contained in nickel metal. Among the rare earth elements, lanthanum, cerium, neodymium and the like can be precipitated and recovered by forming a sulfate double salt by the sulfate double salt precipitation reaction in the rare earth element removal step S5 as described above. However, among the rare earth elements contained in the nickel metal, yttrium (Y) does not form a double salt with the alkali sulfate, and therefore cannot be recovered by precipitation in the rare earth element removal step S5. Although the rare earth element yttrium does not react with the sulfiding agent in the sulfiding step S7, it forms a precipitate in the form of a hydroxide, and the precipitate may be mixed into the nickel / cobalt sulfide. Impair the quality of things.

  Therefore, in the present embodiment, the pH of the acidic solution used for the sulfidation reaction in the sulfidation step S7 is adjusted to a range of pH 2-5. When the pH is lower than 2, nickel / cobalt sulfide is not completely generated by the sulfurization reaction, and sufficient sulfide cannot be obtained. On the other hand, when the pH is higher than 5, yttrium may form a precipitate in the form of hydroxide and may be mixed into the sulfide. In adjusting the pH of the solution, sodium hydroxide, sodium carbonate, or the like is added during the sulfurization reaction to adjust the pH to a range of 2 to 5.

  Thus, in the present embodiment, a sufficient amount of nickel is obtained from the leachate obtained by leaching nickel and cobalt at a high leaching rate by causing a sulfidation reaction while adjusting the pH in the sulfidation step S7. Cobalt sulfide (sulfurized starch) can be obtained, and yttrium can be left in the reaction final solution (sulfurization final solution), so that high-quality nickel-cobalt sulfide can be obtained.

<3. Other embodiments>
The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention.

(Additives with a reducing effect added in the leaching process)
For example, as described above, the metal to be added when leaching the positive electrode active material recovered from the lithium ion battery is not limited to nickel metal recovered from the nickel-hydrogen battery, but nickel, iron, zinc, aluminum It is also possible to use a metal such as Moreover, it is not restricted to using a metal whose potential is lower than that of hydrogen as described above, and a water-soluble reducing agent such as a sulfite having a high reducing effect can also be used.

(Another embodiment of the sulfurization process)
Further, in the above-described sulfiding step S7, an example in which a sulfiding reaction is performed with an alkali sulfide has been described. However, a sulfiding reaction may be generated using hydrogen sulfide as a sulfiding agent. That is, in the sulfidation reaction using hydrogen sulfide, the mother liquor obtained through the leaching step S4 is introduced into a reaction vessel composed of a pressure vessel having pressure resistance, and the sulfide solution contains hydrogen sulfide in the gas phase of the reaction vessel. Gas is blown to cause a sulfurization reaction with hydrogen sulfide in the liquid phase.

This sulfurization reaction using hydrogen sulfide is performed according to the following equation (4) under a predetermined redox potential depending on the hydrogen sulfide concentration in the gas phase.
MSO ₄ + H ₂ S => MS + H ₂ SO ₄ (4)
(M in the formula represents Ni or Co.)

  Although it does not specifically limit as a pressure in the reaction container of the sulfurization reaction of said (4) type, It is preferable that it is 100-300 kPa. The reaction temperature is not particularly limited, but is preferably 65 to 90 ° C.

  Even when the sulfurization reaction based on the formula (4) is performed, it is necessary to adjust the pH of the reaction solution in the range of 2 to 5, thereby allowing Y to remain in the reaction final solution. A high quality sulfide can be obtained.

<4. Example>
EXAMPLES Hereinafter, although this invention is demonstrated using an Example, this invention is not limited to these Examples.

[Leaching process]
A battery disassembled product (Co: 56%, Li: 7%, F: 1.2%) obtained by crushing and crushing a lithium ion battery and then washing with water was mixed with 500 ml of pure water, and the temperature Was heated to 80 ° C.

  Then, a sulfuric acid aqueous solution is added to the solution so that the pH becomes 1.0 to 1.5, and then the nickel-hydrogen (Ni-MH) battery (Ni: 65%, Co: 6%, Mn: 3%, Al: 1.93%, La: 11%, Ce: 5%, Nd: 2%, Y: 1%, Pr: 0.4%) The exfoliated material was added until ORP (reference electrode: silver / silver chloride electrode) of 500 to 550 mV and reacted for 4 hours to form a slurry.

  The slurry after the reaction is filtered using 5C filter paper with an opening of 1 μm, and the filtrate and each component in the residue are analyzed with an ICP emission spectroscopic analyzer (manufactured by SPS3000 SII Nanotechnology Co., Ltd.) to determine the leaching rate. It was. Table 1 shows the leaching rate of each element contained in the leachate.

  As shown in Table 1, 96.7% of Ni, which is a valuable metal contained in the lithium ion battery, is added by adding a recovered material such as nickel metal recovered from the nickel-hydrogen battery in the leaching step. Co, 94% and Li, 97%, respectively, were leached at a high leaching rate. This is considered to be because the positive electrode active material contained in the lithium ion battery could be effectively decomposed and leached out as metal ions due to the strong reduction effect of the added nickel metal.

[Rare earth element removal process]
Next, 262 ml of the leachate obtained in the above-described leaching step was heated to 65 to 70 ° C. while stirring at 300 rpm. Thereafter, sodium sulfate decahydrate (Na ₂ SO ₄ · 10H ₂ O) as a de-RE (rare earth) agent was added in an amount equivalent to 1 equivalent of the total number of moles of rare earth elements in the liquid, and the Na concentration in the final reaction liquid was 6 g / The mixture was added to 1 and stirred for 15 minutes to precipitate and remove rare earth elements contained in the leachate. After completion of the reaction, the sample was filtered, Na ₂ SO ₄ was added to the filtrate, and the slurry was filtered using 5C filter paper with an opening of 1 μm. Each component in the filtrate and the residue was analyzed with an ICP emission spectroscopic analyzer (SPS3000 SII Nanotechnology Co., Ltd.) to determine the precipitation rate.

  Table 2 shows the amount of each element contained in the leaching solution before the rare earth element removal reaction, Table 3 shows the amount of each element contained in the leaching solution after the rare earth element removal reaction (de-RE final solution), and Table 4 Shows the precipitation rate of the de-RE-removed product by the rare earth element removal (de-RE) reaction.

  As shown in Tables 2 to 4, by carrying out the rare earth element removal reaction, rare earth elements (La, Ce, excluding yttrium) are precipitated without precipitating nickel, cobalt, and lithium, which are valuable metals contained in the leachate. Nd) could be precipitated and removed by more than 95%. This is considered to be because only rare earth elements contained in the leachate could be efficiently precipitated and removed as a sulfate double salt by adding an alkali sulfide such as sodium sulfide.

[Neutralization process / sulfurization process]
Next, the reaction final solution obtained in the rare earth element removing step (Table 3) was neutralized, and then nickel and cobalt were recovered.

  First, 227 ml of the reaction final solution obtained through the rare earth element removing step was neutralized to pH 4 by adding an 8 mol / l NaOH aqueous solution as a neutralizing agent while stirring at room temperature at a rotation speed of 300 rpm (neutralization). Process).

Next, 1.1 equivalent of sodium sulfide (Na ₂ S) as a sulfiding agent was added with respect to the contents of nickel and cobalt contained in the reaction final solution. During the addition of the sulfiding agent, the pH was adjusted to 4 with a 64% by weight sulfuric acid (H ₂ SO ₄ ) aqueous solution. After completion of the addition of the sulfiding agent, stirring was continued for 30 minutes while maintaining the pH at 4 to cause a sulfiding reaction.

  Table 5 shows the amount of each element contained in the reaction final solution (sulfurization final solution) at the end of the sulfurization reaction, and Table 6 shows the sulfide precipitation rate of valuable metals formed by the sulfurization reaction. Table 7 shows analytical values of the sulfurized starch formed by the sulfurization reaction.

  As shown in Table 5 and Table 6, by maintaining the pH at 4 and adding 1.1 equivalent of a sulfiding agent to the content of nickel and cobalt, nickel which is a valuable metal contained in a lithium ion battery Cobalt was precipitated and recovered almost completely as a sulfurized starch.

  Further, as can be seen from Table 7, rare earth elements including yttrium can be left in the final solution without being mixed into the sulfide starch, and a high-quality sulfide can be formed. This is considered to be because the pH of the reaction solution could be appropriately controlled during the sulfurization reaction.

[About pH and amount of sulfiding agent added in sulfiding process]
Here, the pH during the sulfidation reaction in the sulfidation step and the addition amount of the sulfiding agent were examined as follows.

  First, in the sulfurization reaction described above, the pH during the sulfurization reaction was adjusted to 2.0, 3.0, and 4.0, respectively, and the cobalt concentration in the solution was examined. The results are shown in FIG.

As can be seen from the results of FIG. 2, even when the pH of the sulfurization reaction solution was adjusted to 2.0, 3.0, or 4.0, the cobalt sulfide was increased by increasing the amount of Na ₂ S added. The production amount of can be increased, and the cobalt concentration in the solution can be reduced. And among them, when the pH of the solution is 4.0, by adding about 1.1 equivalents of Na ₂ S, the cobalt concentration in the solution can be reduced to 0.01 g / l or less, Almost all of the cobalt in the solution could be sulfided with a smaller amount of sulfiding agent than other pH conditions.

Next, in more detail, the relationship between the addition amount of Na ₂ S as a sulfiding agent and the concentrations of nickel and cobalt in the solution was examined. Specifically, the pH of the solution was set to 4.0, and changes in nickel and cobalt concentrations were examined when the amount of Na ₂ S added was changed. The results are shown in FIG.

As can be seen from the results in FIG. 3, the concentration of nickel and cobalt in the solution could be reduced by increasing the amount of Na ₂ S, which is a sulfurizing agent. Further, by setting the amount of Na ₂ S added to 1.1 equivalents, almost all of the nickel and cobalt sulfides present in the solution can be generated, and the concentrations of nickel and cobalt in the solution are reduced to 0 respectively. It was able to be reduced to about 0.001 g / l or less.

Claims (5)

A nickel and cobalt leaching method for leaching nickel and cobalt contained in a positive electrode active material of a lithium ion battery in an acidic solution,
A method for leaching nickel and cobalt, comprising adding a porous nickel plate or reduced roasted powder obtained from a nickel-hydrogen battery to the acidic solution, and leaching nickel and cobalt from the positive electrode active material. The porous nickel plate or reduced roasted powder obtained from the nickel-hydrogen battery is added in an amount of 0.5 to 2.0 times the number of moles of the positive electrode active material to be dissolved. Item 2. The method for leaching nickel and cobalt according to Item 1. A method for recovering valuable metals from a lithium ion battery, comprising:
A leaching step of immersing the positive electrode active material peeled from the lithium ion battery in an acidic solution to which a porous nickel plate or reduced roasted powder obtained from a nickel-hydrogen battery is added, and leaching nickel and cobalt from the positive electrode active material A method for recovering valuable metals, comprising: Furthermore, the addition of leachate alkali sulfate obtained in the leaching step, valuable according to claim 3, wherein the rare earth element contained in the leaching solution, characterized in that have a rare earth element removal step of removing the double sulfate Metal recovery method. Adding a sulfiding agent to the mother liquor obtained through the rare earth element removing step, and adjusting the pH of the mother liquor to 2 to 5 to form a mixed sulfide of nickel and cobalt, The method for recovering valuable metals according to claim 4.

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