WO2019102765A1 - Method for treating lithium ion battery waste - Google Patents

Abstract

Provided is a treatment method whereby it becomes possible to recovery copper, nickel and cobalt, which are valuable metals, contained in a lithium ion battery waste and to separate copper, nickel and cobalt from one another effectively. A method for treating a lithium ion battery waste according to the present invention includes: an alloy production step S1 of introducing the lithium ion battery waste into a furnace and then melting the lithium ion battery waste by heating, thereby producing an alloy containing copper, nickel and cobalt; and an electrolytic purification step S2 of subjecting the alloy to such an electrolytic treatment that the alloy is charged as an anode into a sulfuric acid solution and then electricity is conducted between the anode and a cathode to electrodeposit copper contained in the alloy onto the cathode, thereby separating nickel and cobalt from each other.

Description

Processing method of waste lithium ion battery

The present invention relates to a method for treating waste lithium ion batteries, and more particularly to a treatment method for separating and recovering copper, nickel and cobalt contained in waste lithium ion batteries.

Applications of lithium ion batteries have been expanded for lithium ion batteries whose lifespan has come to an end and they can not be used, and defective members generated in the manufacturing process of lithium ion batteries (hereinafter collectively referred to as “waste lithium ion batteries”) While production numbers are increasing, it is expected to further increase. Such waste lithium ion batteries contain a large amount of valuable metals such as copper, nickel and cobalt, and waste lithium ion batteries are not recycled as industrial waste as they are, but are recovered and recycled. It is desired to do.

However, in waste lithium ion batteries, in addition to the above-mentioned valuable metals, such as metals such as iron and aluminum, which are not economically very high even if recovered with much effort, and as they are recovered as plastic parts. A variety of materials are used, such as substances that are difficult to process, and substances that are technically not easy to recover, such as organic electrolytes containing phosphorus and fluorine, and that can not be discarded as they are on an environmental basis. Therefore, it is not easy to separate them efficiently and recover valuable metals.

In addition, an organic electrolyte used in a lithium ion battery has a high degree of activity, and when used as a battery, the charged charge may remain as it is. Therefore, when the waste lithium ion battery is disassembled carelessly, the positive electrode and the negative electrode of the battery short-circuit, which may cause heat generation or ignition of the electrolyte. As described above, there is also a problem that the handling of the waste lithium ion battery takes care and time.

Therefore, when processing a waste lithium ion battery and recovering valuable metals, first, put the waste lithium ion battery in a furnace and perform processing of melting at a high temperature under high temperature, or process a large amount of waste lithium ion batteries In this case, it is heated (sintered) at a temperature of about 400 ° C. to 600 ° C. necessary for decomposing the electrolytic solution to remove electric charges remaining in the battery and to pretreat the harmless treatment to decompose the organic electrolytic solution. Do as. Next, put the waste lithium ion battery that has been detoxified in an electric furnace etc. and heat it to a higher temperature, subject it to dry treatment to melt valuable metals, and distribute most of iron and aluminum to slag A two-stage melting process has been used in which separation is performed to obtain an alloy metal whose main component is copper, nickel, or cobalt.

The alloy metal obtained by such a conventional method can be reused as ferronickel which is a stainless steel material, but valuable components such as cobalt and copper other than nickel contained in the alloy metal are useless as a stainless steel material. , It can not be recovered effectively and it will be a waste of resources.

Therefore, in order to effectively recover copper and cobalt as well, it is necessary to temporarily dissolve the obtained alloy metal in an acid or the like and then proceed with separation and purification.

However, since copper contained in a waste lithium ion battery is used as an electrode or a wiring material, it is generally larger than the content of nickel, for example, a method of smelting nickel from nickel oxide ore (nickel oxide ore Of the smelting process) can not be used as it is.

As a method of separating copper and nickel and cobalt by leaching an alloy metal with an acid, there is a method disclosed in Patent Document 1, for example. In the process of leaching the alloy with acid, this method dissolves valuable metals such as nickel and cobalt in the leaching solution while leaving most of the copper in the solid state, so that the copper dissolved in the solution after leaching It is a method that can simplify or omit the process required for removal, improve the process efficiency, and reduce the process cost.

Specifically, the heating step of heating the lithium ion battery to 450 ° C. to 650 ° C., and the battery powder obtained after the heating step are required to dissolve all the metal components contained in the battery powder. Leach with a leachate containing 2-fold molar equivalent to 1.5-fold molar equivalent of sulfuric acid, and simultaneously measure the leaching potential before the redox potential (ORP) of the leachate exceeds 0 mV with a silver / silver chloride electrode as the reference electrode And a final leaching step.

The method disclosed in the patent document 1 and so-called selective leaching method has an advantage that it can be processed efficiently. However, when it is desired to leach the alloy with acid, it is often necessary to use a gas such as oxygen or air or an oxidant such as hydrogen peroxide. In addition, there is a problem that it takes time and effort in facilities and operation, such as heating the acid solution to raise the temperature.

Thus, it was not easy to separate copper from nickel and cobalt by efficiently acid dissolving an alloy containing copper, nickel and cobalt.

JP, 2017-36489, A

The present invention has been proposed in view of such circumstances, and recovers valuable metals copper, nickel, and cobalt from waste lithium ion batteries, and effectively separates copper from nickel and cobalt. Intended to provide a method that can be

As a result of intensive investigations, the inventor of the present invention melts a waste lithium ion battery to obtain an alloy containing copper, nickel and cobalt, and then performs electrolytic treatment in a sulfuric acid solution using the alloy as an anode. As a result, the inventors have found that the problems described above can be effectively solved, and have completed the present invention.

(1) A first invention according to the present invention comprises an alloy forming step of melting a waste lithium ion battery by charging it into a furnace and heating it to obtain an alloy containing copper, nickel and cobalt; Electrolytic purification process of separating copper contained in the alloy on the cathode and separating it from nickel and cobalt by charging in a sulfuric acid acidic solution as an electrode and subjecting it to electrolytic treatment in which current is applied between the anode and the cathode. And a method of treating a waste lithium ion battery.

(2) the second invention of the present invention, in the first aspect, the the electrolytic purification step, and the anode current density of 3A / m ² or more 3000A / m ² or less in the range, of the waste lithium ion batteries It is a processing method.

(3) In a third invention of the present invention according to the first or second invention, in the electrolytic refining step, the copper concentration in the sulfuric acid acidic solution which is an electrolytic solution is in the range of 5 g / L to 50 g / L. Is a processing method of a waste lithium ion battery, in which the electrolytic processing is performed while maintaining the

(4) In a fourth invention according to any one of the first to third inventions, the alloy contains phosphorus in a range of 0.5% by weight or more and 2.0% by weight or less, It is a processing method of the waste lithium ion battery which uses the said alloy as an anode in refinement | purification.

(5) In the fifth invention of the present invention according to any one of the first to fourth inventions, the electrolytic solution after the electrolytic treatment in the electrolytic purification step is supplied to an electrolytic cell, and the electrolysis is carried out using an insoluble anode. It is a processing method of a waste lithium ion battery which further has an electrowinning process of electrodepositing copper which remained in liquid.

(6) A sixth aspect of the present invention is the waste lithium according to the fifth aspect, wherein the electrolytic solution discharged from the electrolytic cell through the electrolytic collection step is repeatedly supplied as an electrolytic solution used in the electrolytic purification step. It is a processing method of an ion battery.

(7) In the seventh invention of the present invention according to the first invention, at least a part of the electrolytic solution obtained after the electrolytic treatment in the electrolytic purification step is recovered, and an oxidizing agent and a neutralizing agent are added to the electrolytic solution. The method further includes an impurity removal step of removing an impurity component by adjusting the redox potential (reference electrode: silver / silver chloride electrode) to be 570 mV or more and the pH to be in the range of 3 to 5 by adding Thereafter, sulfuric acid is added to the filtrate obtained by solid-liquid separation to adjust the pH to 1.5 or less, and the filtrate after pH adjustment is repeatedly supplied as an electrolyte used in the electrolytic purification step, waste lithium ion It is a battery processing method.

(8) In the eighth invention of the present invention according to the first invention, at least a part of the electrolytic solution obtained after the electrolytic treatment in the electrolytic purification step is recovered, and the pH of the electrolytic solution is 1.5 or less. An oxidizing agent is added to the electrolytic solution at a stage to adjust the redox potential (reference electrode: silver / silver chloride electrode) to be 570 mV or more, and then an oxidizing agent and a neutralizing agent are further added, The method further comprises an impurity removal step of removing the impurity component by raising the pH to 3 and adjusting the redox potential to be 300 mV or more, and then adding sulfuric acid to the filtrate obtained by solid-liquid separation The pH is adjusted to 1.5 or less, and the filtrate after pH adjustment is repeatedly supplied as an electrolytic solution used in the electrorefining step.

According to the method of the present invention, valuable metals copper, nickel and cobalt can be recovered from a waste lithium ion battery, and the copper and nickel and cobalt can be effectively separated.

It is a graph which shows the relationship between pH of the electrolyte solution from which nickel grade in copper electrodeposited on a cathode is 0.1 weight% or less, and a cathode current density.

Hereinafter, specific embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, A various change is possible in the range which does not change the summary of this invention. Further, in the present specification, the notation “X to Y” (X and Y are arbitrary numerical values) means “more than X and less than Y”.

The method for treating a waste lithium ion battery according to the present invention (hereinafter, also simply referred to as “treatment method”) is a treatment method for recovering valuable metals copper, nickel and cobalt from waste lithium ion batteries such as used batteries. is there. Here, the term "waste lithium ion battery" is a generic term for scraps such as waste materials generated in the manufacturing process of the above-described used lithium ion battery and lithium ion battery.

Specifically, in the method of treating a waste lithium ion battery according to the present invention, the waste lithium ion battery is melted by being introduced into a furnace and heated to obtain an alloy forming step S1 for obtaining an alloy containing copper, nickel and cobalt. And copper contained in the alloy is electrodeposited on the cathode to obtain nickel and cobalt by subjecting the obtained alloy as an anode to a sulfuric acid solution and subjecting it to an electrolytic treatment in which current is applied between the anode and the cathode. And electrorefining step S2 to be separated.

As described above, in the processing method according to the present invention, for example, after melting a waste lithium ion battery roasted by a dry method to obtain an alloy (alloy metal), an electrolytic method is used to melt the obtained alloy. That is, instead of dissolving the obtained alloy directly with acid or the like, the alloy is used as an anode to conduct electricity and electrolytic treatment is performed to elute copper, nickel and cobalt from the alloy into the electrolytic solution. At the same time, copper on the cathode is electrodeposited on the cathode side on the cathode side.

According to such a treatment method, it is possible to efficiently separate solid copper obtained by electrodeposition and a solution in which nickel and cobalt are eluted. Since nickel and cobalt can be used, for example, as a battery active material, according to such a treatment method, a solution containing nickel and cobalt recovered in a state separated from copper from a waste lithium ion battery can be used as it is. It can be used as a raw material for producing substances.

[Alloy formation process]
In the alloy formation step S1, the waste lithium ion battery is put into a furnace and melted to melt it, thereby obtaining an alloy containing copper, nickel and cobalt. That is, in the alloy formation step, it is affirmation to form an alloy containing copper, nickel and cobalt which are valuable metals contained in the waste lithium ion battery.

In the alloy formation step S1, first, it is put into a roasting furnace of a waste lithium ion battery and roasted at a temperature of, for example, 300 ° C. to 1000 ° C., more preferably 500 ° C. to 900 ° C. By performing such roasting treatment, the electrolytic solution contained in the waste lithium ion battery can be decomposed, volatilized and removed. In addition, the structure including the casing contained in the waste lithium ion battery can be easily separated and removed by controlling the roasting temperature based on the melting point of the material forming the structure.

Next, in the alloy formation step S1, the roasted product (post-baked product) obtained after the roasting treatment is put into a melting furnace such as a graphite crucible or a magnesium crucible, for example, to about 1100 ° C. to 1400 ° C. Melt under high temperature conditions. Such a melting process makes it possible to almost completely melt the roasted product and to form an alloy containing copper, nickel and cobalt.

In the melting process in the melting furnace, the roasted product can be treated, for example, by being introduced together with an oxide-based flux. The flux is not particularly limited, and calcium oxide, magnesium oxide, silicon oxide and the like can be mentioned.

Here, iron may also be contained in the alloy obtained by the melting process.

In addition, lithium ion batteries may use an electrolyte containing phosphorus in addition to fluorine such as hexafluorophosphoric acid, among which fluorine is easily volatilized and removed by roasting treatment. , Part of the phosphorus may be distributed to the alloy. Therefore, the alloy obtained by the melting process may contain a part of phosphorus, and is alloyed with copper and exists as phosphorus-containing copper or a form similar thereto. However, if such an alloy containing phosphorus is used in the electrolytic treatment as the anode, passivation of the anode can be made difficult to occur, and the electrolytic treatment is carried out at a high current density to make the electrolytic solution It can be dissolved in it.

[Electrolytic purification process]
In the electrolytic refining step S2, the obtained alloy (an alloy containing copper, nickel and cobalt) is charged as an anode in a sulfuric acid acidic solution to carry out electrolytic treatment.

Specifically, an alloy containing copper, nickel, and cobalt is used as an anode, and a stainless steel plate or the like is used as a cathode, and the anode and the cathode are charged face to face in an electrolytic cell. Then, it is subjected to an electrolytic treatment by energizing between the anode and the cathode.

By performing such electrolytic treatment, copper, nickel, and cobalt are eluted from the alloy constituting the anode into the electrolytic solution, and then copper, which is a noble metal, is preferentially deposited on the cathode (electrodeposition). ). As a result, nickel and cobalt remaining in the electrolytic solution can be effectively separated from copper without being electrodeposited on the cathode. Even when iron is contained in the alloy constituting the anode, the iron eluted in the electrolyte remains in the same manner as nickel and cobalt and is effectively separated from copper.

Here, as the electrolytic solution, a sulfuric acid acidic solution is used, and the concentration of sulfuric acid is not particularly limited. For example, it is preferable to use a solution in a concentration range of 1% by mass to 70% by mass. Here, the sulfuric acid concentration of the electrolytic solution composed of a sulfuric acid acidic solution is the sulfuric acid concentration of the initial electrolytic solution at the start of energization.

If the concentration of sulfuric acid in the electrolytic solution is less than 1% by mass, the concentrations of soluble copper, nickel, and cobalt may not increase and productivity may be reduced. In addition, in the case of an electrolytic solution with a low sulfuric acid concentration, the electric conductivity is lowered and the voltage is increased, resulting in a loss. Furthermore, if the concentration of copper that can be dissolved is not high, the electrodeposition of copper on the cathode is not smooth and tends to be powdery or granular, and it is not preferable because nickel and cobalt are entrapped in the electrodeposition gaps, leading to a decrease in separability. .

On the other hand, if the concentration of sulfuric acid in the electrolyte exceeds 70% by mass, it is not economical, and if it is an excessively high concentration electrolyte, passivation tends to occur in which the dissolution of metal from the anode is suppressed. Become. In addition, after dissolution in the electrolytic solution, re-dissolution of copper electrodeposited at the cathode is also likely to occur. Furthermore, it is necessary to use equipment such as piping and an electrolytic bath having durability to an electrolytic solution composed of high concentration sulfuric acid, which tends to lead to an increase in cost and a decrease in productivity.

Moreover, as an electrolyte solution, it is preferable to adjust the pH to the range of 0 or more and 1.5 or less, and to perform an electrolysis process. Thus, copper, nickel, and cobalt can be more efficiently dissolved from the alloy, and only copper can be electrodeposited more selectively thereafter. If the pH of the electrolytic solution is less than 0, the acid may be too strong and the electrodeposited copper may be easily redissolved. On the other hand, when the pH of the electrolyte exceeds 1.5, not only copper but also nickel and cobalt may tend to be electrodeposited.

When using an alloy containing copper, nickel and cobalt as an anode, it is cast into a plate-like shape like an electrode plate. Then, prepare cathode plates (stainless steel plates, titanium plates) of the same size, and place them face-to-face, for example, so that the distance between electrodes (distance between surfaces) is 10 mm to 40 mm. .

The anode current density is not particularly limited, it is preferable to 3A / ^{m 2} or more 3000A / ^{m 2} or less in the range, and more preferably to 100A / ^{m 2} or more 2000A / ^{m 2} or less.

If the current density of the anode is less than 3 A / m ² , the production efficiency may be degraded, for example, by requiring an extra facility. On the other hand, when the current density of the anode exceeds 3000 A / m ² , passivation tends to occur on the anode side, and the liquid resistance by the electrolyte between the anode and the cathode increases, so the process The overall power cost increases and efficient processing can not be performed. Furthermore, the heat generation of the electrolytic treatment increases, which may cause problems in terms of material and safety. Furthermore, it is not preferable that components other than copper are easily electrodeposited on the cathode.

Here, the current density of the cathode is preferably equal to or lower than the above-mentioned range of the anode current density. By setting the current density of the cathode in this manner, copper eluted from the anode can be deposited more efficiently on the cathode. In the processing method according to the present invention, copper eluted from the anode is electrodeposited on the cathode, while nickel and cobalt are kept dissolved to separate copper from nickel and cobalt. From this fact, if the electrodeposition of copper is not efficiently performed, it will be a loss from the viewpoint of electric power, which is not preferable.

In order to lower the current density of the cathode relative to the current density of the anode, for example, a cathode having a structure in which the electrode area of the cathode is larger than the electrode area of the anode may be used.

In addition, the inventor has found that the pH of the electrolyte is in the range of 0 to 1.2 between the pH of the electrolyte from which an electrodeposit having a nickel grade of less than 0.1% by weight is obtained and the cathode current density (Dk). In
Dk (A / m ² ) =-2062 × pH + 3002 (Equation 1)
Found that the relationship that That is, by performing electrolytic purification at a current density equal to or lower than the current density calculated by the above-mentioned formula 1 for a predetermined pH, the quality of nickel deposited on the cathode can be suppressed to less than 0.1% by weight. it can.

As described above, in the electrolytic treatment in the electrolytic refining step S2, copper, nickel, cobalt, iron and the like are dissolved in the electrolytic solution from the alloy used as the anode, and then the dissolved copper is preferentially electrodeposited on the cathode Although it will come out, it is preferable to adjust so that the copper concentration in the electrolyte solution at this time may be maintained in the range of 5 g / L to 50 g / L.

If the concentration of copper dissolved in the electrolyte is less than 5 g / L, nickel and cobalt dissolved in the electrolyte also tend to be electrodeposited on the cathode, and can not be effectively separated from copper There is sex. In addition, when copper ions in the electrolytic solution become insufficient, water is electrolyzed at the cathode to generate hydrogen gas, and as a result, the pH of the electrolytic solution is increased to promote the tendency of nickel and cobalt to be electrodeposited. There is a possibility of On the other hand, when the copper concentration in the electrolytic solution exceeds 50 g / L, the copper concentration in the electrolytic solution may be excessive, and the separation from nickel and cobalt may be insufficient.

In addition, as described above, the alloy obtained through the alloy formation step S1 may contain phosphorus derived from the electrolyte solution of the waste lithium ion battery. Thus, by using a phosphorus-containing alloy as the anode, passivation of the anode can be less likely to occur, and electrolytic treatment can be performed at a high current density. The concentration of phosphorus in the alloy is not particularly limited, but is preferably in the range of, for example, 0.5% by weight or more and 2.0% by weight or less.

Phosphorus is considered to be present in the form of copper phosphide (CuP), nickel phosphide (NiP), etc. in the alloy serving as the anode, but as copper, nickel, and cobalt are eluted from the alloy during electrolysis, Phosphorus is concentrated in the deposit formed as slime on the anode surface. When the phosphorus concentration in the alloy is less than 0.5% by weight, it is difficult to obtain the above-described effect of suppressing passivation of the anode. On the other hand, when the phosphorus concentration is more than 2.0% by weight, the time for slime treatment and the time for partially removing the phosphorus eluted in the electrolytic solution are increased. Moreover, when further refine | purifying the electrolyte solution from which nickel and cobalt were leached by electrolytic refining, the effort which removes the phosphorus as an impurity will increase.

The concentration of phosphorus in the anode slime tends to proceed as the acid concentration of the electrolytic solution is lower and the anode current density is smaller. Therefore, the total amount of phosphorus in the alloy does not elute in the electrolytic solution in the range of the preferred acid concentration in the treatment in the electrolytic purification step S2 and the range of the anode current density as described above. Since it is necessary to separate and remove from the electrolytic solution (separate and remove in the impurity removing step described later) when reusing a part of the electrolytic solution in the electrolytic purification step S2, the phosphorus eluted in the electrolytic solution needs time and effort In consideration of this, it is preferable that the proportion of phosphorus distributed to the anode slime be 20% or more.

As described above, in the treatment method according to the present invention, the alloy containing copper, nickel and cobalt obtained in the alloy formation step S1 is used as an anode, and is inserted into the electrolyte of a sulfuric acid acidic solution And electrolytic treatment. Then, copper, nickel, and cobalt contained in the alloy are dissolved in the electrolytic solution, and only copper is preferentially deposited on the cathode and recovered, whereby copper, nickel, and cobalt are effectively removed. And efficiently separate.

According to such a method, valuable metals such as copper, nickel and cobalt can be effectively recovered from the waste lithium ion battery by a simple method of electrolytic treatment, and copper and nickel and cobalt are separated. It can be collected in the state.

When an alloy containing iron is used, iron as well as nickel and cobalt remains in the electrolytic solution as described above, but a solution containing these nickel, cobalt and iron (sulfuric acid By subjecting the acid solution to a known purification treatment, the respective metal components can be separated easily and with high purity. For example, a purification method such as a solvent extraction process using an extractant capable of selectively extracting each metal can be applied.

Moreover, the elution amount of the metal component eluted in the electrolytic solution by the electrolytic treatment can be controlled by the amount of electricity supplied between the anode and the cathode. Moreover, according to the electrolytic treatment, since blowing of an oxidizing agent and air is unnecessary, power and motive power for air supply are unnecessary other than the power for electrolysis, and the acid-containing mist is There is no environmental deterioration such as scattering around, and stable operation can be performed.

[Electrolytic collection process]
Furthermore, the electrolytic solution after the electrolytic treatment in the electrolytic refining step S2 may be supplied to the electrolytic cell to carry out the electrolytic treatment, and the electrolytic collection step S3 may be carried out to cause the copper remaining in the electrolytic solution to be electrodeposited.

The amount of copper dissolved in the electrolytic solution fluctuates according to the amount of copper in the alloy, the amount of electrification in the electrolytic treatment in the electrolytic refining step S2, etc., and the amount of copper electrodeposited on the cathode also changes. When copper is contained in the electrolytic solution obtained through the electrolytic refining step S2, the separability from nickel and cobalt becomes insufficient. Therefore, an electrolytic collection step S3 is performed in which the electrolytic treatment is performed using the electrolytic solution after the electrolytic treatment in the electrolytic purification step S2 (the electrolytic solution in which copper remains), whereby the copper remaining in the electrolytic solution is electrodeposited. Do the process of

Specifically, in the electrolytic collection step S3, the electrolytic solution after the electrolytic treatment in the electrolytic purification step S2 is supplied to a predetermined electrolytic cell, and copper remaining in the electrolytic solution is electrodeposited using an insoluble anode.

According to such a method, copper in the electrolytic solution recovered through the electrolytic refining step S2 can be deposited and recovered, and separated from nickel and cobalt contained in the electrolytic solution with high separation property, Highly pure solutions of nickel and cobalt can be obtained.

The electrolytic solution to be subjected to electrolytic collection (the electrolytic solution after the electrolytic treatment in the electrolytic purification step S2) is preferably adjusted to pH 1.5 or less, more preferably pH 1.0 or less. In electrowinning, the cathode current density is preferably in the range of 1 A / m ^{2 to} 2000 A / m ² , more preferably in the range of 1 A / m ^{2 to} 1500 A / m ² . In addition, in the process of electrowinning, as the insoluble anode, one in which a platinum group oxide is coated on the electrode surface as a catalyst is generally used, and among them, one of the kind called oxygen generation type may be used preferable.

Although the electrolytic solution obtained through the electrowinning step S3 can be used as a treatment start solution for extracting and separating nickel and cobalt as described above, at least a part thereof is electrorefining step S2 It may be repeatedly used as an electrolytic solution in

[Repetitive use of electrolyte: Impurity removal process]
Now, when the electrolytic solution after the electrolytic treatment in the electrolytic refining step S2 or the electrolytic solution after the electrolytic treatment in the electrolytic collection step S3 is performed, the electrolytic solution after the electrolytic treatment is a solution in which mainly nickel and cobalt are dissolved. . As described above, the electrolytic solution containing nickel and cobalt obtained by separating it from copper by electrolytic treatment is then subjected to known purification treatment such as solvent extraction treatment to thereby obtain high purity of nickel and cobalt respectively. It can be recovered as a solution containing it.

On the other hand, at least a part of the electrolytic solution obtained through such an electrolytic process can be repeatedly used again as an electrolytic solution of the electrolytic process in the electrolytic purification step S2. Thereby, the copper remaining in the electrolytic solution can be electrodeposited on the cathode by the treatment in the electrolytic refining step S2 repeatedly used to enhance the copper recovery rate, and also enhance the separation of nickel and cobalt. Can.

Here, as described above, the alloy to be subjected to the treatment in the electrolytic refining step S2, that is, the alloy containing copper, nickel, and cobalt obtained by melting the waste lithium ion battery in the alloy forming step S1 May contain iron. Moreover, the phosphorus derived from the electrolyte solution of a waste lithium ion battery may be contained. These components such as iron and phosphorus are eluted in the electrolytic solution by the electrolytic treatment in the electrolytic purification step S2 using the alloy as an anode. Thus, the electrolyte is a solution containing iron and phosphorus together with nickel and cobalt.

When such an electrolytic solution is subjected to known purification treatment such as solvent extraction treatment to selectively purify nickel and cobalt, those valuable metals can be used as impurity components such as iron and phosphorus. The components can be separated and recovered effectively. However, for example, when a part of the electrolytic solution is repeatedly used as the electrolytic solution used in the electrolytic treatment in the electrolytic refining step S2, it is preferable to remove components such as iron and phosphorus as impurity components as much as possible. . If components such as phosphorus are not removed, there also arises a problem that it becomes difficult to efficiently use selectively leached nickel or cobalt as a material of a battery again.

Therefore, when the electrolytic solution obtained through the electrolytic purification step S2 or the electrolytic collection step S3 is repeatedly used again, the impurity component contained in the electrolytic solution prior to supplying the electrolytic cell in the electrolytic purification step S2 Is separated and removed (impurity removal step).

(Impurity removal process)
For example, Patent Document 2 discloses a method of separating phosphorus. Specifically, a nickel compound containing a phosphorus compound and a cobalt component as impurities is dissolved in an inorganic acid to form a nickel solution containing the phosphorus compound and the cobalt component, and an oxidizing agent is added to the nickel solution. The phosphorus compound is precipitated as a phosphate by precipitation, and this is removed by solid-liquid separation, and a nickel oxide (Ni ₂ O ₃ ), which is a substance different from the oxidizing agent, is added to the nickel solution. A cobalt removing step is disclosed, which comprises oxidizing and then neutralizing and precipitating the cobalt component and removing it by solid-liquid separation. Then, in this method, the cobalt removal step is carried out after the phosphorus removal step, or the phosphorus removal step and the cobalt removal step are carried out simultaneously to carry out the oxidation of the cobalt component by nickel oxide after the oxidation of the phosphorus compound by the oxidizing agent. It is something to do. However, the concentration at which phosphorus can be separated by this method is shown to be about 5 mg / L according to the example of Patent Document 2, and the separation effect is further enhanced for use as a battery application. Is desired.

On the other hand, in the present embodiment, specifically, at least a part of the electrolytic solution obtained after the electrolytic treatment in the electrolytic purification step S2 is recovered, and the oxidizing agent and the neutralizing agent are added to the electrolytic solution. The redox potential (ORP) using a silver / silver chloride electrode as a reference electrode is adjusted so as to be in the range of 570 mV or more and the pH in the range of 3 to 5. Thus, by adjusting the ORP and pH of the electrolytic solution with the oxidizing agent and the neutralizing agent, iron or phosphorus, which are impurity components contained in the electrolytic solution, are simultaneously or selectively precipitated and effectively separated and removed. can do. The separation and removal of the precipitate containing the impurity component can be performed by solid-liquid separation of the electrolytic solution after the treatment with the oxidizing agent and the neutralizing agent as described later.

The oxidizing agent and the neutralizing agent are not particularly limited as long as the ORP and the pH can be adjusted to the above-mentioned ranges, respectively. For example, as the oxidizing agent, hydrogen peroxide water, oxygen gas, ozone gas or the like can be used as appropriate.

Moreover, when performing oxidation treatment and neutralization treatment by adding an oxidizing agent and a neutralizing agent, it is preferable if the temperature condition is room temperature or higher, but if it exceeds 60 ° C., the phosphorus concentration in the electrolytic solution after dephosphorization Is preferably 60.degree. C. or less, because it may increase.

Moreover, in the removal of impurities such as phosphorus, it may be processed as follows. That is, first, at least a part of the electrolytic solution obtained after the electrolytic treatment in the electrolytic purification step S2 is recovered, and an oxidizing agent is added in a pH state where the pH of the electrolytic solution is 1.5 or less. Adjust the (ORP) to 570 mV or more, then add a neutralizer to raise the pH to 3, and add an oxidant to adjust the ORP to 300 mV or more. As described above, by performing the two-stage oxidation treatment, iron and phosphorus which are impurity components contained in the electrolytic solution may be precipitated simultaneously or selectively.

After these treatments, the electrolyte after treatment with the oxidizing agent and the neutralizing agent is subjected to solid-liquid separation, and sulfuric acid is added to the obtained filtrate to adjust the pH to 1.5 or less. As described above, since a precipitate of iron or phosphorus can be generated in the electrolytic solution by the treatment using the oxidizing agent and the neutralizing agent, the solid-liquid separation treatment is performed on the electrolytic solution containing the precipitate. Thus, the precipitate which is solid content is separated and removed. Then, the filtrate obtained after solid-liquid separation is recovered, and sulfuric acid is added to the filtrate to obtain a sulfuric acid solution having a pH of 1.5 or less.

The filtrate after pH adjustment is a sulfuric acid acidic solution after pH adjustment with sulfuric acid, and a solution after separation and removal of impurity components such as iron and phosphorus. Therefore, by supplying the solution (filtrate) obtained by such treatment to the electrolytic cell in the electrolytic purification step S2, it can be effectively used as an electrolytic solution of electrolytic treatment without bringing iron, phosphorus, etc. .

Although the case where the electrolytic solution after the electrolytic treatment in the electrolytic purification step S2 is repeatedly used again has been described, the electrolytic solution obtained in the electrolytic collection step S3 after the electrolytic purification step S2 is also obtained. By applying the same treatment, a solution (filtered solution after treatment) from which the impurity component has been separated and removed can be used as an electrolytic solution in the electrolytic purification step S2.

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

Example 1
(Alloy formation process)
First, the waste lithium ion battery was put in a roasting furnace and roasted at a temperature of 500 ° C. to decompose and volatilize and remove the electrolytic solution contained in the waste lithium ion battery to obtain a roasted product. Subsequently, the obtained roasted product was placed in a furnace made of a graphite crucible and heated to 1100 ° C. to be completely melted to obtain an alloy.

(Electrolytic purification process)
Next, the obtained alloy was cast into a plate-like anode. As the anode, a portion to be an electrode surface is 50 mm long × 50 mm wide, and 10 mm thick. As a result of sampling analysis, the composition of the anode was copper: 65% by weight, nickel: 15% by weight, cobalt: 15% by weight, iron: 2% by weight, and phosphorus: 1% by weight.

On the other hand, using a titanium plate having an electrode surface of the same size as that of the cast anode and having a thickness of 3 mm as a cathode, in an electrolytic cell made of polyvinyl chloride, the distance between the anode plate and the cathode plate Face to face at a distance of 20 mm. In addition, the side which does not face an other party electrode with the anode and the cathode was insulated with the masking tape.

In addition, a sulfuric acid solution having a sulfuric acid concentration of 10% by mass was used as an electrolytic solution (electrolytic initial solution), and self circulation was performed by extracting it from one end of the electrolytic cell with a pump and supplying the other end. The temperature of the electrolyte was 30 ° C. (room temperature).

Using such an electrolytic device, electrolytic treatment was performed at an anode current density of 300 A / m ² . As a result, the alloy used as the anode was easily dissolved, and powdery copper having a purity of 99.9% or more was deposited on the cathode.

As described above, valuable metals copper, nickel and cobalt can be recovered from the waste lithium ion battery, and in particular, copper and nickel and cobalt can be separated and recovered.

Example 2
The polarization of the anode surface was measured by a potential scanning method using a commercially available potentiostat using an electrolyte of the same composition and the same anode as in Example 1.

As a result, it was confirmed that the anode side was not passivated even if the electrolytic treatment was performed at a current density where the anode current density exceeded 3000 A / m ² .

Comparative Example 1
In Comparative Example 1, the waste lithium ion battery was roasted in the same manner as in Example 1, and then the roasted product was melted to obtain an alloy.

Next, the obtained alloy was dropped into water while being melted to obtain a water splitting shot, and the obtained water splitting shot was further crushed. Thereafter, a shot after grinding was placed in a sulfuric acid solution having a sulfuric acid concentration of 20% by mass, and a method of dissolving while heating to a temperature of 60 ° C. to 70 ° C. was tried. However, the whole amount could not be dissolved.

[Example 3]
In the same manner as in Example 1, the waste lithium ion battery is roasted and subjected to a dry treatment to melt the roasted product, and copper: 65% by weight, nickel: 15% by weight, cobalt: 15% by weight, iron: An alloy having a composition of 2% by weight and phosphorus: 1% by weight was obtained. Thereafter, the obtained alloy was cast on a plate-like anode, and electrolytic treatment was performed using a sulfuric acid solution having a sulfuric acid concentration of 10% by mass as an electrolytic solution. The anode current density was 300 A / m ^2, and the temperature of the electrolyte was 30 ° C. (room temperature).

After the end of energization, the electrolyte and the slime attached to the anode surface were respectively recovered and analyzed to determine the distribution of phosphorus. As a result, the distribution ratio of phosphorus from the alloy used as the anode to slime was 34%. This result greatly exceeds the target value of 20% of the distribution ratio of phosphorus to slime, and therefore, the elution of phosphorus contained in the alloy into the electrolyte can be suppressed and it can be effectively separated from nickel and cobalt. The

Example 4
Using the alloy and equipment having the same composition as in Example 3, an electrolytic treatment was performed using a sulfuric acid solution with a sulfuric acid concentration of 20% by mass as the electrolytic solution and an anode current density of 2000 A / m ² .

As a result, the distribution ratio of phosphorus from the alloy used as the anode to slime was 30%. This result greatly exceeds the target value of 20% of the distribution ratio of phosphorus to slime, and therefore, the elution of phosphorus contained in the alloy into the electrolyte can be suppressed and it can be effectively separated from nickel and cobalt. The

Comparative Example 2
Using the alloy and equipment having the same composition as in Example 3, an electrolytic treatment was performed using a sulfuric acid solution with a sulfuric acid concentration of 40% by mass as the electrolytic solution and an anode current density of 4000 A / m ² .

As a result, it was found that the distribution ratio of phosphorus from the alloy used as the anode to slime was 5%, and 95% of phosphorus was eluted in the electrolyte. In this state, when separating and recovering nickel or cobalt eluted in the electrolytic solution, it is necessary to carry out a dephosphorization treatment, or it has become necessary to intensify the treatment.

Example 5 Comparative Example 3
The waste lithium ion battery was roasted in the same manner as in Example 1, and the resulting roasted product was subjected to a dry treatment to obtain an alloy having the same composition as that in Example 1. Thereafter, the obtained alloy was cast on a plate-like anode, and electrolytic treatment was performed using a sulfuric acid solution having a sulfuric acid concentration of 20% by mass as an electrolytic solution. In addition, pH of the electrolyte solution before an electrolytic treatment (before electricity supply) was 0.

In this electrolytic treatment, current was applied while changing the cathode current density from 500 A / m ² to 3000 A / m ² . The pH of the electrolyte gradually increased as the current was applied. Then, when the pH of the electrolytic solution reached a predetermined value, the copper deposited on the cathode was recovered, and the recovered copper was washed and dried for chemical analysis.

Table 1 below shows the analysis results of copper electrodeposited on the cathode in the relation between the cathode current density and the electrolyte pH. The notation “o” in Table 1 indicates that the copper was electrodeposited with high purity without the nickel being electrodeposited. Also, the notation “<0.1” indicates that although only slight electrodeposition of nickel was confirmed, the nickel grade was less than 0.1% by weight. The expressions “0.1” and “0.3” indicate that the nickel grade was 0.1% by weight and 0.3% by weight, respectively. Further, the notation “NG” indicates that nickel was electrodeposited and the nickel grade exceeded 0.3% by weight.

As shown in Table 1, it can be seen that electrodeposition of nickel tends not to occur when the cathode current density is low and the pH of the electrolyte is low. However, it can be seen that as the pH is increased by energization and the current density is increased, nickel tends to start to be electrodeposited (co-deposited) together with copper.

In addition, when the conditions of the cathode current density and pH described in “<0.1” in Table 1 are plotted and graphed, the graph shown in FIG. 1 is obtained. And the linear regression which connected each point is
Dk = -2062 × pH + 3002
It becomes. That is, it shows that when the current density is higher than the cathode current density (Dk) with respect to the pH of the regression equation, nickel co-precipitates with copper electrodeposited on the cathode. Therefore, by using such a formula to control the current density at the limit where nickel does not precipitate while measuring the pH of the electrolytic solution, high-purity copper is efficiently electrodeposited to be separated from nickel and cobalt. can do.

[Example 6]
The waste lithium ion battery was roasted in the same manner as in Example 1, and the resulting roasted product was subjected to a dry treatment to obtain an alloy having the same composition as that in Example 1. Thereafter, the obtained alloy was cast into a plate-like anode, and electrolytic treatment was performed using a titanium plate as a cathode and a sulfuric acid solution having a sulfuric acid concentration of 20% by mass as an electrolytic solution. The pH of the electrolyte was adjusted to 1. Further, the temperature of the electrolytic solution was set to 30 ° C. (room temperature).

When the cathode current density was set to 1500 A / m ² and current was supplied, the alloy of the anode was easily dissolved. In addition, when copper was electrodeposited on the cathode and the electrodeposited copper was analyzed, the copper grade was 99.9% by weight or more.

Next, add an aqueous solution of hydrogen peroxide to the electrolytic solution after electrolytic treatment (the electrolytic solution after copper is separated and collected), and refer to the silver / silver chloride electrode for the redox potential (ORP) of the electrolytic solution. The potential was adjusted to 570 mV at the potential of the electrode, and at the same time, the pH was adjusted to 4 by adding sodium hydroxide. Then, the electrolyte after adjusting the ORP and pH was subjected to solid-liquid separation, and the obtained filtrate was subjected to chemical analysis.

As a result, the iron concentration in the filtrate was 2 mg / L or less, and the phosphorus concentration could be reduced to 1 mg / L.

Comparative Example 4
In Comparative Example 4, the filtrate obtained by solid-liquid separation was treated in the same manner as in Example 6 except that the pH of the electrolytic solution after the electrolytic treatment was adjusted to 2, and the chemical analysis was performed.

As a result, the iron concentration in the filtrate was 2000 mg / L, the phosphorus concentration was 500 mg / L, and iron and phosphorus were contained at a significantly higher concentration than in Example 6. Thus, in Comparative Example 4, the phosphorus in the electrolyte could not be reduced to the target of 5 mg / L or less.

[Example 7]
An alloy having the same composition as in Example 1 was used as an anode, and electrolytic processing was performed under the same conditions to dissolve the alloy, and copper was electrodeposited on the cathode. The electrolytic solution from which copper was separated and recovered after the electrolytic treatment (liquid after electrolytic elution) had a Ni concentration of 20 g / L, a Co concentration of 20 g / L, and a Cu concentration of 10 g / L. In addition, the pH of the solution after the elution was 1.

Next, electrolytic collection processing was performed by using the obtained post-electrolytic solution as an electrolytic starting solution. Specifically, using an oxygen-generating insoluble anode coated on the electrode surface with a platinum group oxide catalyst as the anode, using a titanium plate as the cathode, and using a cathode current density of 1500 A / m ² for electrowinning treatment went. This electrolytic treatment was performed until the copper concentration of the electrolytic solution was reduced to 1 g / L, and then the power was cut off to recover and analyze the copper deposited on the cathode.

As a result, the grade of copper electrodeposited on the cathode was 99.9% by weight. Further, when the electrolytic final solution after separation and recovery of copper was analyzed, it was found that the concentrations of nickel and cobalt did not change before and after electrolysis, and from this point as well, nickel and cobalt co-deposition did not occur.

[Example 8]
After the electrowinning treatment performed in Example 7, the cathode current density was set to 300 A / m ² , and electrowinning was continued until the copper concentration of the electrolytic solution became 0.5 g / L.

As a result, the grade of copper electrodeposited on the cathode was 99.0% by weight. Further, when the electrolytic final solution after separation and recovery of copper was analyzed, it was found that the concentrations of nickel and cobalt did not change before and after electrolysis, and from this point as well, nickel and cobalt co-deposition did not occur.

Comparative Example 5
The pH of the solution after electrolytic elution was adjusted to 3, and using the solution after pH adjustment as the electrolyte starting solution, the electrolytic extraction treatment was performed under the conditions of a cathode current density of 3000 A / m ^2, and Example 7 and It processed similarly.

As a result, the copper grade of the deposited material electrodeposited on the cathode was 82% by weight, nickel eutectic was confirmed, and copper could not be separated and recovered in a high purity state. Moreover, when the electrolytic final solution after separating and collecting copper was analyzed, the concentration of nickel fluctuated before and after the electrolysis, and from this point also, the co-precipitation of nickel was confirmed.

The following Table 2 shows the measurement results of the conditions of the electrowinning in Examples 7 and 8 and Comparative Example 5 and the concentrations of the respective components of the electrolytic initial solution and the electrolytic final solution.

Claims (8)

An alloy formation step of melting by charging a waste lithium ion battery into a furnace and heating to obtain an alloy containing copper, nickel and cobalt;
Copper contained in the alloy is electrodeposited on the cathode to separate it from nickel and cobalt by charging the alloy as an anode in a sulfuric acid solution and subjecting it to electrolytic treatment in which a current is applied between the anode and the cathode. And an electrolytic purification step of processing the waste lithium ion battery. Wherein in the electrolytic refining step, the processing method of waste lithium ion battery according to claim 1 in the range of current density of the anode 3A / m ² or more 3000A / m ² or less. The waste lithium ion battery according to claim 1 or 2, wherein in the electrolytic refining step, the electrolytic treatment is performed while maintaining the copper concentration in the sulfuric acid acidic solution which is an electrolytic solution in a range of 5 g / L to 50 g / L. Processing method. The alloy contains phosphorus in the range of 0.5 wt% to 2.0 wt%,
The method for treating a waste lithium ion battery according to any one of claims 1 to 3, wherein the alloy is used as an anode in the electrolytic refining. The method according to any one of claims 1 to 4, further comprising: supplying an electrolytic solution after the electrolytic treatment in the electrolytic purification step to an electrolytic cell, and using an insoluble anode to electrodeposited copper remaining in the electrolytic solution. The processing method of the waste lithium ion battery as described in. The processing method of a waste lithium ion battery according to claim 5, wherein the electrolytic solution discharged from the electrolytic cell through the electrolytic collection step is repeatedly supplied as an electrolytic solution used in the electrolytic purification step. At least a part of the electrolytic solution obtained after the electrolytic treatment in the electrolytic purification step is recovered, an oxidizing agent and a neutralizing agent are added to the electrolytic solution, and the redox potential (reference electrode: silver / silver chloride electrode) is The method further includes an impurity removing step of removing an impurity component by adjusting so as to be 570 mV or more and pH in a range of 3 or more and 5 or less,
Thereafter, sulfuric acid is added to the filtrate obtained by solid-liquid separation to adjust the pH to 1.5 or less, and the filtrate after pH adjustment is repeatedly supplied as an electrolytic solution used in the electrorefining step. Processing method of the waste lithium ion battery of statement. At least a part of the electrolytic solution obtained after the electrolytic treatment in the electrolytic purification step is recovered, and an oxidizing agent is added to the electrolytic solution at a stage where the pH of the electrolytic solution is 1.5 or less, Electrode: Adjust the silver / silver chloride electrode to 570 mV or more, and then add an oxidizing agent and a neutralizing agent to raise the pH to 3 and adjust the redox potential to 300 mV or more Further includes an impurity removing step of removing the impurity component by
Thereafter, sulfuric acid is added to the filtrate obtained by solid-liquid separation to adjust the pH to 1.5 or less, and the filtrate after pH adjustment is repeatedly supplied as an electrolytic solution used in the electrorefining step. Processing method of the waste lithium ion battery of statement.

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