JP2012036419A - Method for removing phosphorus and/or fluorine, and method for recovering valuable metal from lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for removing phosphorus and/or fluorine for recovering high-quality valuable metal by preventing the formation of salt with the valuable metal by efficiently removing phosphorus and fluorine from the leachate of a positive electrode active material, and to provide a method for recovering valuable metal using the removing method.SOLUTION: At least one compound selected from the group consisting of a Ca compound, Mg compound, Al compound, and rare earth compound is added to the leachate obtained by leaching the positive electrode active material of a lithium ion battery using an acidic solution. Adjustment is performed so that pH of the leachate is 2-4.

Description

  The present invention relates to a method for removing phosphorus and / or fluorine and a method for recovering valuable metals from a lithium ion battery, and in particular, efficiently removes phosphorus and / or fluorine from a leachate of a positive electrode active material of a lithium ion battery, The present invention relates to a phosphorus and / or fluorine removal method capable of recovering valuable metal and a method for recovering valuable metal from a lithium ion battery to which the removal 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 and aluminum. Further, when lithium hexafluorophosphate (LiPF ₆ ) is contained as an electrolyte, there is a problem that the consumption of the furnace material is remarkable.

  On the other hand, as described in Patent Documents 3 and 4, methods for recovering valuable metals by wet processing have also been proposed. However, even in these methods, since a dry process is partially used, the consumption of heat energy is large. And in particular, in these conventional methods for recovering valuable metals by wet processing, the disadvantage is that impurities are mixed into valuable metals contained in the positive electrode active material, and valuable valuable metals cannot be recovered. was there.

That is, in wet processing, 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. However, in the leachate from which the valuable metal is leached, phosphorus (P) and fluorine (F) contained in LiPF _{6 and the} like contained as the electrolyte of the lithium ion battery are valuable metals such as nickel (Ni). And form a salt with cobalt (Co) and the like. Then, the recovered valuable metals became poor quality metals containing phosphorus and fluorine, and also caused poor drainage quality.

  Thus, in the conventional method for recovering valuable metals from lithium ion batteries by wet processing, phosphorus, fluorine, etc. are mixed into valuable metals, and efficient recovery of valuable metals is not possible.

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 a situation, and prevents phosphorus and fluorine from being efficiently removed from the leachate of the positive electrode active material of a lithium ion battery to form a valuable metal and salt. Another object of the present invention is to provide a method for removing phosphorus and / or fluorine capable of recovering valuable metals of good quality, and a method of recovering valuable metals from lithium ion batteries to which the removing method is applied.

  As a result of intensive studies in order to achieve the above object, the present inventors have obtained a calcium (Ca) compound, a magnesium (Mg) compound, aluminum in a leachate obtained by leaching a positive electrode active material of a lithium ion battery with an acidic solution or the like By adding at least one compound selected from the group consisting of (Al) compounds and rare earth compounds and adjusting the pH to a predetermined range, phosphorus and fluorine contained in the leachate can be efficiently removed, and valuable metals The present inventors have found that the formation of a salt with nickel, cobalt or the like can be suppressed, and the present invention has been completed.

  That is, the present invention is a phosphorus and / or fluorine removal method for removing phosphorus and / or fluorine from a leachate obtained by leaching a positive electrode active material of a lithium ion battery with an acidic solution, wherein the leachate contains a Ca compound, Mg At least one compound selected from the group consisting of a compound, an Al compound, and a rare earth compound is added, and the pH of the leachate is adjusted to be 2 to 4.

  Further, the present invention is a valuable metal recovery method for recovering valuable metals from a lithium ion battery, wherein a Ca compound, an Mg compound, an Al compound is added to a leachate obtained by leaching the positive electrode active material of the lithium ion battery with an acidic solution. And adding at least one compound selected from the group consisting of rare earth compounds, adjusting the pH of the leachate to 2 to 4, and removing phosphorus and / or fluorine contained in the leachate And / or a fluorine removal step.

  According to the present invention, phosphorus and / or fluorine can be efficiently removed from a leachate obtained by leaching a positive electrode active material of a lithium ion battery with an acidic solution, and valuable metals contained in the positive electrode active material are phosphorus and fluorine. It is possible to prevent the formation of salt and recover valuable valuable metals.

It is a figure which shows the process of the collection | recovery method of the valuable metal from a lithium ion battery.

  Hereinafter, a method for removing phosphorus and / or fluorine according to the present invention and a method for recovering valuable metals from a lithium ion battery to which the removal 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 3. Wastewater treatment process after the sulfurization process Other Embodiments 5. Example

<1. Summary of the present invention>
The present invention relates to a method for removing phosphorus and / or fluorine and a method for recovering valuable metals from a lithium ion battery to which the removal method is applied, and includes phosphorus (P), fluorine (F), etc. contained in the lithium ion battery. In this method, the valuable metal of the positive electrode active material is prevented from being contaminated, and the valuable metal with good quality is recovered.

Conventionally, when recovering a valuable metal from a lithium ion battery, the positive electrode active material peeled from the lithium ion battery is leached with an acidic solution. As a result, valuable metals such as nickel (Ni) and cobalt (Co) contained in the lithium ion battery are sufficiently leached, and the slurry is subjected to a sulfidation reaction and the like to efficiently recover the valuable metals. be able to. However, by using an acidic solution during leaching, phosphorus (P) and fluorine (F) contained in LiPF _{6 and the} like constituting the electrolyte of a lithium ion battery form a salt with nickel, cobalt and the like to be recovered. It was. As a result, the quality of valuable metals such as nickel and cobalt and poor drainage were caused, and the valuable metals could not be efficiently recovered.

  Therefore, in the present invention, phosphorus and fluorine contained in the electrolytic solution and the like are removed prior to recovering valuable metals such as nickel and cobalt by a sulfurization reaction or the like. Specifically, the present invention adds at least one compound selected from the group consisting of Ca compounds, Mg compounds, Al compounds, and rare earth compounds to a leachate obtained by leaching a positive electrode active material of a lithium ion battery with an acidic solution. At the same time, the pH of the leachate is adjusted to 2-4.

  Hereinafter, an embodiment (hereinafter referred to as “the present embodiment”) relating to a method for recovering a valuable metal from a lithium ion battery to which the present invention is applied will be described in more detail.

<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 a crushing / disintegrating step S1, a positive electrode active material peeling step S2, a leaching step S3, a P and F removing step S4, and a sulfiding step S5.

(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. In that case, since it is dangerous when the battery is charged, 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) Positive electrode active material peeling step In the positive electrode active material peeling step S2, the battery disassembled product obtained through the crushing / disintegrating step S1 is immersed in an acidic solution such as an aqueous sulfuric acid solution or a surfactant solution. The positive electrode active material is peeled off and separated from the positive electrode substrate. 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 S2, 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 step, all of the battery disassembled material may be immersed in a sulfuric acid aqueous solution or a surfactant solution, but only the positive electrode material portion may be selected from the battery disassembled material and immersed in the sulfuric acid aqueous solution.

  When an aqueous sulfuric acid solution is used as the acidic solution, the pH of the acidic solution is controlled to be 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 an anionic surfactant, 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.

  In addition, since the separation time of the positive electrode active material in the positive electrode active material peeling step S2 varies depending on the concentration of the sulfuric acid aqueous solution and the surfactant solution, the input amount and size of the battery disassembled material including the positive electrode material, etc. It is preferable to keep it.

  The disassembled battery after the positive electrode active material peeling step S2 is sieved, and the positive electrode active material such as lithium nickelate and lithium cobaltate separated from the positive electrode substrate, and the accompanying substances are collected. 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.

(3) Leaching step In the leaching step S3, the positive electrode active material peeled and recovered in the positive electrode active material peeling step S2 is leached with an acidic solution to form a slurry. By this leaching step S3, the positive electrode active material is dissolved in an acidic solution, and nickel, cobalt, etc., which are valuable metals constituting the positive electrode active material, are used as metal ions.

  As an 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 least 2 or less, and more preferably controlled to about 0.5 to 1.5 in consideration of reactivity. Since the pH increases 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.

  Moreover, in this leaching process S3, the leaching rate of nickel and cobalt from the positive electrode active material can be improved by adding a metal or compound having a high reducing effect such as nickel metal or fixed carbon-containing material to the acidic solution. it can. 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.

  For example, the addition amount of a metal having a high reducing effect such as nickel metal is preferably 0.5 to 2.0 times the mole of the positive electrode active material to be dissolved. Further, it is preferable to add nickel metal so that the oxidation-reduction potential (ORP) (reference electrode: silver / silver chloride electrode) is 500 to 550 mV.

  The amount of the fixed carbon-containing material added is generally preferably about 50 to 300% by weight based on the weight of the positive electrode active material to be dissolved, and in the case of graphite or negative electrode powder having a high fixed carbon content, 50 to About 100% by weight is preferable. The fixed carbon-containing material can be recovered and reused after the dissolution reaction.

(4) P, the F removal step P, F removing step S4, leaching from leachate of the obtained positive electrode active material in the step S3, contained in the lithium hexafluorophosphate constituting the electrolyte (LiPF ₆₎ or the like Remove phosphorus (P) and fluorine (F).

As described above, in the leaching step S3, since an acidic solution is used to improve the leaching rate of valuable metals such as nickel and cobalt, a compound such as LiPF ₆ constituting the electrolytic solution is phosphoric acid (H ₃ PO ₄ ) and hydrogen fluoride (HF), etc., existed in the leaching solution, and these phosphorus and fluorine formed salts with metal ions such as leached nickel and cobalt. Therefore, in the present embodiment, at least one compound selected from the group consisting of a calcium (Ca) compound, a magnesium (Mg) compound, an aluminum (Al) compound, and a rare earth compound in the leachate obtained in the leaching step S3. Add. Further, the pH of the leachate is adjusted to 2 to 4, more preferably about pH 3.

  In the present embodiment, by treating the leachate from which valuable metals have been leached in this way, phosphorus or fluorine contained in the leachate is precipitated as fluoride or phosphate by the added Ca compound or the like. Can do. By removing the precipitate from the leachate, phosphorus and fluorine can be removed from the leachate, so that valuable metals such as nickel and cobalt can be recovered efficiently and effectively without contamination by the phosphorus and fluorine. can do.

  Examples of the Ca compound, Mg compound, and Al compound to be added include hydroxides, chlorides, nitrates, and sulfates. Further, as rare earth compounds, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu hydroxide, chloride, nitrate, sulfate Etc.

  In the P and F removal step S4, as described above, at least one compound selected from the group consisting of Ca compounds, Mg compounds, Al compounds, and rare earth compounds is added, and the pH of the leachate is 2-4. It is important to control the range.

  Form phosphorus and fluorine and salt in the leachate with the added Ca compound, etc., and form a salt with nickel or cobalt whose valuable metal is phosphorus or fluorine to be removed by setting the pH of the leachate to 2 or more Can be prevented, and recovery loss of valuable metals can be suppressed.

On the other hand, by adjusting the pH of the leachate to 4 or less, the solubility of formed fluorides and phosphates such as CaF ₂ and Ca (PO ₄ ) ₂ can be lowered, and phosphorus and Fluorine can be precipitated and removed. Further, it is possible to prevent nickel and cobalt to be collected from forming a salt with the added Ca compound, thereby preventing the occurrence of a recovery loss.

  In the P and F removal step S4, phosphorus and fluorine are efficiently precipitated and removed from the leachate, and nickel and cobalt, which are valuable metals to be recovered, are effectively left and effectively recovered. It makes it possible to recover nickel and cobalt at a rate.

  In addition, pH adjustment of a leaching solution may be adjusted with the Ca compound etc. to add, and you may adjust by adding a pH adjuster as needed. The pH adjuster is not particularly limited. For example, as the alkaline pH adjuster, an alkali salt such as sodium hydroxide, calcium hydroxide, sodium carbonate, cobalt carbonate or the like can be used. In this case, mineral acids such as hydrochloric acid and sulfuric acid can be used.

  Here, in the P and F removal step S4, about 60% of phosphorus and fluorine contained in the leachate are removed by precipitation. The reason is, for example, when it is attempted to recover 60% or more of phosphorus or fluorine, it is necessary to increase the amount of Ca compound or the like added. Then, the pH of the leachate can no longer be controlled within the range of 2 to 4, and as a result, the recovery loss of nickel and cobalt to be recovered and the increase in the solubility of the generated phosphorus and fluorine salts, This is because defective removal is caused and valuable metals cannot be recovered efficiently and effectively.

  About 40% of phosphorus and fluorine that have not been removed in the P and F removal step S4 are sent to the sulfurization step S5. However, these phosphorus and fluorine do not cause a sulfurization reaction with the sulfidizing agent, and nickel / cobalt sulfide. The quality of the sulfide is not impaired because no precipitation and coprecipitation occur. Therefore, by performing the treatment as described above, it is possible to effectively prevent phosphorus and fluorine from being mixed into the sulfides of nickel and cobalt in the subsequent sulfiding step S5.

  The mother liquor (P, F removal reaction final solution) obtained by removing the precipitates of fluoride and phosphate through the P, F removal step S4 is then sent to the sulfidation step S5, where it is sulfided. The reaction recovers valuable metals nickel and cobalt as nickel-cobalt sulfide. On the other hand, the phosphorus, fluorine fluoride, phosphate, etc. formed in the P and F removal step S4 are removed as a residue.

(5) Sulfurization step In the sulfurization step S5, the solution obtained through the P and F removal step S4 is introduced into a reaction vessel, and a sulfurization reaction is caused by adding a sulfurizing agent to produce a nickel / cobalt mixed sulfide. By doing so, valuable metals nickel and cobalt 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 S5, nickel ions (or cobalt ions) contained in the solution obtained through the P and F removal step S4 are caused by alkali sulfide according to the following formula (1) or (2). It becomes sulfide by the sulfurization reaction.
Ni ²⁺ + NaHS ⇒ NiS + H ⁺ + Na ⁺ (1)
Ni ²⁺ + Na ₂ S ⇒ NiS + 2Na ⁺ (2)

  As the addition amount of the sulfiding agent in the sulfiding step S5, 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.

  The pH of the solution used for the sulfurization reaction in the sulfurization step S5 is preferably about pH 2-4. In addition, the temperature of the sulfurization reaction in the sulfurization step S5 is not particularly limited, but is preferably 70 to 95 ° C, and 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., an economic problem such as high cost for increasing the temperature There are many.

  As described above, nickel and cobalt contained in the positive electrode active material of the lithium ion battery can be recovered as nickel / cobalt sulfide (sulfurized starch) by the sulfurization reaction in the sulfurization step S5. The nickel / cobalt sulfide obtained here is a nickel / cobalt sulfide that is not contaminated by phosphorus or fluorine since phosphorus and fluorine are removed from the leachate in the P and F removal step S4 described above. Moreover, in the P and F removal step S4, the pH is adjusted to 2 to 4 to prevent nickel and cobalt from being removed by precipitation in the P and F step S4. Nickel and cobalt, which are valuable metals, can be recovered from the ion battery at a high recovery rate.

  On the other hand, the sulfidation final liquid (poor liquid) produced through the sulfidation step S5 in which nickel and cobalt are recovered as sulfides is discharged.

  As described above, in the method for recovering valuable metals from a lithium ion battery according to the present embodiment, when recovering nickel or cobalt, which are valuable metals recovered from a lithium ion battery, By efficiently removing phosphorus and fluorine, the valuable metal can be recovered efficiently and effectively without deteriorating the quality of the valuable metal and without causing a recovery loss.

<3. Wastewater treatment process after sulfurization process>
Incidentally, as described above, in the present embodiment, in the P and F removal step S4, about 60% of phosphorus and fluorine contained in the leachate are recovered. Therefore, about 40% of the phosphorus and fluorine that are not removed in the P and F removal step S4 are sent to the sulfurization step S5. However, these phosphorus and fluorine do not cause a sulfurization reaction with the sulfidizing agent, and nickel / cobalt sulfide. There is no precipitation and coprecipitation of substances, and it is contained in the drainage as a final sulfurization liquid after the sulfide is recovered. However, drainage containing phosphorus and fluorine requires a very complicated drainage treatment, and requires a drainage treatment device and labor. It is preferable to remove effectively prior to the treatment.

  Therefore, in the present embodiment, at least one compound selected from the group consisting of Ca compounds, Mg compounds, Al compounds, and rare earth compounds is added to the sulfurized final solution containing phosphorus and fluorine, and A drainage treatment step S6 for adjusting the pH of the drainage to be 8 to 10 can be performed.

  In the present embodiment, by treating the sulfurization final solution containing phosphorus and fluorine in this way, the phosphorus and fluorine contained in the sulfurization final solution are converted into fluoride and phosphoric acid by the added Ca compound and the like. It can be precipitated as a salt. Then, by removing the precipitate from the sulfurized final solution, it becomes a drained liquid that does not contain phosphorus or fluorine. Therefore, the burden of the drained liquid treatment can be reduced, and an efficient drained process can be performed. .

  As the Ca compound, Mg compound, Al compound, and rare earth compound to be added, the same compounds as those used in the above-described P and F removal step S4 can be used.

  In this drainage treatment step S6, as described above, at least one compound selected from the group consisting of Ca compounds, Mg compounds, Al compounds, and rare earth compounds is added, and the pH of the leachate is in the range of 8-10. It is important to control.

In this drainage treatment step S6, the added Ca compound or the like forms phosphorus and fluorine and salt in the final sulfur solution, and the pH of the final sulfur solution is 8 or more, thereby forming phosphate and fluoride. On the other hand, by setting the pH of the sulfurization final solution to 10 or less, the solubility of formed fluorides and phosphates such as CaF ₂ and Ca (PO ₄ ) ₂ is minimized. And phosphorus and fluorine can be efficiently removed by precipitation.

  In addition, pH adjustment of the sulfurization final solution may be adjusted by the Ca compound to be added, or may be adjusted by adding a pH adjuster as necessary.

<4. 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.

(Another embodiment of the sulfurization process)
For example, in the above-described sulfiding step S5, the example in which the sulfiding reaction is performed with an alkali sulfide has been described. However, the sulfiding reaction may be generated using hydrogen sulfide as a sulfiding agent. That is, in the sulfurization reaction using hydrogen sulfide, the solution obtained through the P and F removal step S4 is introduced into a reaction vessel composed of a pressure vessel having pressure resistance, and hydrogen sulfide is introduced into the gas phase of the reaction vessel. A sulfurizing gas containing hydrogen sulfide is generated in a liquid phase by blowing in a sulfurizing gas.

This sulfurization reaction using hydrogen sulfide is performed according to the following equation (3) under a predetermined oxidation-reduction potential that depends on the hydrogen sulfide concentration in the gas phase.
MSO ₄ + H ₂ S => MS + H ₂ SO ₄ (3)
(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 (3) type, It is preferable that it is 100-300 kPa. The reaction temperature is not particularly limited, but is preferably 65 to 90 ° C.

(Another embodiment of nickel / cobalt recovery)
Further, the method for recovering valuable metals from the lithium ion battery according to the present invention is not limited to the method of recovering valuable metals such as nickel and cobalt as sulfides by a sulfurization reaction using alkali sulfide or hydrogen sulfide. .

  Specifically, for example, as a nickel / cobalt recovery step, a neutralizer is added to the solution obtained through the P and F removal step S4 to adjust the pH to 6.5 to 10, and nickel and cobalt starches are added. You may make it form. Through this nickel / cobalt recovery process, nickel and cobalt contained in the lithium ion battery are recovered. As the neutralizing agent used here, general chemicals such as soda ash, slaked lime, and sodium hydroxide can be used.

<5. Example>
EXAMPLES Hereinafter, although this invention is demonstrated using an Example, this invention is not limited to these Examples.

Example 1
First, the discharged lithium ion battery was disassembled into a size of 1 cm square or less by a biaxial crusher. The battery disassembled product was immersed in water and subjected to a peeling operation by stirring to recover the positive electrode active material from the positive electrode substrate.

Next, the collected positive electrode active material was immersed in a sulfuric acid aqueous solution so as to have a slurry concentration of 50 g / L, and valuable metals constituting the positive electrode active material were leached. Then, Ca (OH) ₂ (mixed with water to form a slurry of 20% by weight) was added to the leachate, and the pH was adjusted to about 3. Thereafter, the precipitate was filtered.

  About 60% of phosphorus and fluorine contained in the leachate could be separated from the precipitate.

Next, sodium sulfide (Na ₂ S) was added as a sulfiding agent to the filtrate from which phosphorus and fluorine precipitates had been removed, and nickel and cobalt were recovered as sulfides while maintaining pH 3. Phosphorus and fluorine contained in the sulfide could be suppressed to 0.01% or less.

Next, Ca (OH) ₂ (mixed with water to form a 20% by weight slurry) was added to the effluent to adjust to pH 9. Thereby, the remaining 40% of phosphorus and fluorine could also be separated.

(Comparative Example 1)
Nickel and cobalt were recovered under the same conditions as in Example 1 except that no addition treatment of Ca (OH) ₂ was performed.

  As a result, 60% of phosphorus and fluorine contained in the positive electrode active material after the peeling operation were mixed in the sulfides of nickel and cobalt, and 40% were transferred to drainage.

Claims (4)

A method for removing phosphorus and / or fluorine, which removes phosphorus and / or fluorine from a leachate obtained by leaching a positive electrode active material of a lithium ion battery with an acidic solution,
At least one compound selected from the group consisting of Ca compounds, Mg compounds, Al compounds, and rare earth compounds is added to the leachate, and the pH of the leachate is adjusted to 2 to 4, To remove phosphorus and / or fluorine. A method for recovering valuable metals from a lithium ion battery, comprising:
At least one compound selected from the group consisting of Ca compounds, Mg compounds, Al compounds and rare earth compounds is added to a leachate obtained by leaching the positive electrode active material of the lithium ion battery with an acidic solution, and the pH of the leachate A method for recovering a valuable metal, comprising a step of removing phosphorus and / or fluorine that is adjusted to be 2 to 4 and removes phosphorus and / or fluorine contained in the leachate.   A sulfurizing agent is added to the solution obtained through the phosphorus and / or fluorine removing step to form a mixed sulfide of nickel and cobalt contained in the leachate to recover nickel and cobalt. The method for recovering valuable metals according to claim 2.   At least one compound selected from the group consisting of Ca compounds, Mg compounds, Al compounds and rare earth compounds is added to the solution from which the mixed sulfide of nickel and cobalt has been recovered by the sulfiding step, and the pH of the solution 4. The method for recovering a valuable metal according to claim 3, further comprising a drainage treatment step of adjusting phosphorus to 8 to 10 and removing phosphorus and / or fluorine.

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