JP2023035964A - Processing method of alloy - Google Patents

Abstract

To provide a method of efficiently obtaining a solution containing nickel and/or cobalt from an alloy containing nickel and/or cobalt, and copper of a waste lithium ion battery and the like.SOLUTION: A processing method of alloy for obtaining a solution containing nickel and/or cobalt from an alloy containing nickel and/or cobalt, and copper includes a leach process of subjecting a slurry containing the alloy to leach processing by an acid solution in the presence of a sulfating agent to obtain a leachate and a leach residue. In the leach process, the leach processing is performed by adjusting an initial concentration of the slurry containing the alloy to 100 g/L or more and 250 g/L or less. Also in the leach process, the leach processing is performed preferably while controlling an oxidation reduction potential (a silver/silver chloride electrode as a reference electrode) to 200 mV or lower. Also in the leach process, the leach processing is performed preferably in the presence of the sulfating agent by an amount in a range of 1.05-1.25 equivalent (S mol/Cu mol) to an amount of copper contained in the alloy.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method of processing an alloy to obtain a solution containing nickel and/or cobalt from an alloy containing nickel and/or cobalt and copper.

Vehicles such as electric vehicles and hybrid vehicles, and electronic devices such as mobile phones, smartphones, and personal computers are equipped with lithium ion batteries (hereinafter also referred to as “LIB”), which are lightweight and have high output.

LIB is a negative electrode material in which a copper foil is used as a negative electrode current collector and a negative electrode active material such as graphite is adhered to the surface inside an outer can made of metal such as aluminum or iron or plastic such as vinyl chloride, A positive electrode material in which a positive electrode active material such as lithium nickel oxide or lithium cobalt oxide is fixed to a positive electrode current collector made of aluminum foil is charged together with a separator made of a polypropylene porous resin film or the like, and lithium hexafluorophosphate is charged. It has a structure in which an organic solvent containing an electrolyte such as (LiPF ₆ ) is impregnated as an electrolytic solution.

When LIBs are used in vehicles and electronic devices as described above, they eventually become unusable due to the deterioration of automobiles and electronic devices, or due to the life of LIBs themselves. ). Note that "waste LIB" includes those generated as defective products in the manufacturing process.

These waste LIBs contain valuable components such as nickel, cobalt, and copper, and it is desired to recover and reuse these valuable components for effective utilization of resources.

In general, when trying to efficiently recover valuable components from devices, members, and materials made of metal, the dry process involves putting them into a furnace or the like, melting them at high temperatures, and separating the metal containing valuables from the other slag. Dry processing using the principle of smelting has been widely practiced. For example, Patent Literature 1 discloses a method of recovering valuable metals using dry processing. By applying the method disclosed in Patent Document 1 to the recovery of valuable metals from waste LIB, a copper alloy containing nickel and cobalt can be obtained.

Such a dry process (hereinafter also referred to as a "dry process") has the disadvantage of requiring energy for heating to a high temperature using a furnace, but has the advantage of being able to separate various impurities all at once. Moreover, the slag obtained by dry processing has the advantage of being chemically stable, having little concern about affecting the environment, and being easy to dispose of.

However, when the waste LIB is treated by dry treatment, there is a problem that some valuable components, especially most of the cobalt, are distributed to the slag, resulting in recovery loss of the cobalt. In addition, the metal obtained by dry processing is an alloy in which valuable components coexist, and in order to reuse it, it is necessary to separate each component from this alloy and refine it to remove impurities.

As a method of element separation generally used in dry processing, a method is known in which, for example, copper and lead are separated by slow cooling from a high-temperature molten state, or lead and zinc are separated. ing. However, when the main components are copper and nickel, such as waste LIB, the copper and nickel have the property of uniformly melting over the entire composition range, so even if it is slowly cooled, the copper and nickel will only mix and solidify in layers. cannot be separated.

Furthermore, there is also a refining method that disproportionates nickel using carbon monoxide (CO) gas to volatilize and separate it from copper and cobalt, but it is said that it is difficult to ensure safety because it uses toxic CO gas. There is also a problem.

Further, as a method for separating copper and nickel that has been industrially practiced, there is a method for roughly separating a mixed matte (sulfide). In this method, a matte containing copper and nickel is generated in the smelting process, and then slowly cooled in the same manner as in the above case to separate the sulfide containing a large amount of copper and the sulfide containing a large amount of nickel. is. However, even with this separation method, the separation of copper and nickel is limited to a crude separation, and in order to obtain nickel and copper with high purity, a separate treatment such as electrolytic refining is required.

In addition, a method of utilizing a vapor pressure difference via chloride has also been investigated. However, since this is a process in which a large amount of toxic chlorine is handled, it requires large-scale measures against corrosion of equipment, safety measures, etc., and it is difficult to say that it is an industrially suitable method.

Thus, each elemental separation and refinement in the dry process has the drawback of staying at the crude separation level or increasing the cost.

On the other hand, wet processing (hereinafter also referred to as “wet processing”) using hydrometallurgical methods using acid treatment, neutralization treatment, solvent extraction treatment, etc. consumes less energy and separates mixed valuable ingredients. There is an advantage that it can be separated into a large amount and recovered in a high-purity grade.

However, when wet processing is used to treat waste LIB, hexafluorophosphate anions and other constituents of the electrolytic solution contained in waste LIB are difficult-to-process substances that cannot be completely decomposed even at high temperatures and high concentrations of sulfuric acid. and will contaminate the leached acid solution with valuable components. Since the hexafluorophosphate anion is a water-soluble carbonate ester, it is difficult to recover phosphorus and fluorine from the aqueous solution after recovery of valuables. There are significant environmental restrictions, such as the need to take measures such as

Furthermore, it is not easy to obtain a solution that can be efficiently leached and purified from waste LIB using only acid. In particular, the waste LIB body is difficult to leach out with acid or the like, and it is not easy to leach out the valuable components completely. In addition, if a strong oxidizing acid is used to forcibly leach out, along with valuable components, even impurity components such as aluminum, iron, and manganese, which are not subject to industrial recovery, are leached out. The cost of the neutralizing agent for treatment increases, and problems arise in that the amount of waste water and sediments generated increases. Furthermore, the waste LIB may have residual electric charge, and if it is to be disposed of as it is, it may cause heat generation, explosion, or the like.

Processing waste LIBs by using only wet processing in this way is not necessarily an advantageous method.

Therefore, the waste LIB, which is difficult to process by the above-mentioned dry process or wet process alone, is treated by a method that combines the dry process and the wet process, that is, by a dry process such as roasting the waste LIB, removing impurities as much as possible and uniform waste. Attempts have been made to obtain a LIB-processed product and separate the resulting processed product into valuable components and other components by wet processing.

In such a method that combines dry and wet processes, the fluorine and phosphorus in the electrolytic solution are volatilized and removed by the dry process, and the structural parts of the waste LIB, such as plastics and organic materials such as separators, are also thermally decomposed. be. In addition, since the waste LIB processed material is obtained in a uniform state through the dry process, it can be easily handled as a uniform raw material even in the wet process.

However, the problem of recovery loss that cobalt contained in the waste LIB is distributed to the slag still remains with the mere combination of dry and wet processes.

For example, by adjusting the treatment conditions in the dry process, it is possible to efficiently distribute cobalt to the metal rather than to the slag, and reduce the distribution to the slag for reduction melting. However, the metal obtained by such a method is a sparingly soluble, corrosion-resistant alloy containing nickel and cobalt with a copper base. Even if an attempt is made to separate and recover valuable components from this corrosion-resistant alloy by wet treatment, acid dissolution is difficult and effective recovery is not possible.

When, for example, chlorine gas is used to leach the corrosion-resistant alloy, the resulting solution (leaching solution) contains high concentrations of copper and relatively low concentrations of nickel and cobalt. Among them, nickel and cobalt can be easily separated by using a known method such as solvent extraction, but it is difficult to separate copper from nickel and cobalt easily and at low cost.

The recovery of valuable metals from waste LIBs has attracted attention as an effective use of urban mines, and has been actively developed in recent years. However, as described above, in the existing wet treatment method, the concentration of nickel and/or cobalt in the solution containing nickel and/or cobalt obtained from the alloy derived from waste LIB is low, and concentration and purification of the obtained solution are difficult. It has a problem of high cost.

The above-mentioned problems also exist when nickel and/or cobalt and copper are separated from waste batteries other than waste LIBs. It also exists in the case of separating the

JP 2012-172169 A

The present invention has been proposed in view of such circumstances, and efficiently obtains a solution containing nickel and/or cobalt from an alloy containing nickel and/or cobalt and copper such as a waste lithium ion battery. The purpose is to provide a method.

As a result of intensive studies by the present inventors, the initial concentration of the slurry containing the alloy containing nickel and/or cobalt and copper is adjusted to a specific range and the leaching treatment is performed to achieve a high concentration of nickel and/or cobalt. It was found that it is possible to obtain a solution containing Also, preferably, the leaching treatment is performed while controlling the oxidation-reduction potential (reference electrode: silver/silver chloride electrode) within a specific range, and preferably, the sulfiding agent is specified with respect to the amount of copper contained in the alloy. It has been found that nickel and/or cobalt can be leached out more efficiently and effectively by coexisting in an amount within the range of . Specifically, the present invention provides the following.

(1) A first aspect of the present invention is a method of treating an alloy for obtaining a solution containing nickel and/or cobalt from an alloy containing nickel and/or cobalt and copper, wherein the slurry containing the alloy is and performing leaching treatment with an acid solution in the presence of a sulfiding agent to obtain a leaching solution and a leaching residue, wherein the initial concentration of the slurry containing the alloy is 100 g/L or more and 250 g/L. It is an alloy treatment method in which leaching treatment is performed by adjusting the following.

(2) In a second aspect of the present invention, in the first aspect, in the leaching step, the leaching process is performed while controlling the oxidation-reduction potential (the reference electrode is a silver/silver chloride electrode) to 200 mV or less. It is a method of treating alloys.

(3) A third invention of the present invention is the first or second invention, wherein in the leaching step, the sulfiding agent is added in an amount of 1.05 to 1.25 equivalents with respect to the amount of copper contained in the alloy. This is a method of treating an alloy in which leaching treatment is performed in the coexistence of an amount in the range of (S-mol/Cu-mol).

(4) In a fourth aspect of the present invention, in any one of the first to third aspects, a reducing agent is added to the leached solution obtained through the leaching step to perform a reduction treatment, and after reduction, A method of treating an alloy further comprising a reduction step to obtain a liquid and a reduction residue.

(5) A fifth aspect of the present invention is the method according to any one of the first to third aspects, wherein a neutralizing agent and an oxidizing agent are added to the reducing solution obtained through the reducing step to oxidize the The alloy treatment method further includes an oxidation-neutralization step of performing a neutralization treatment to obtain a post-oxidation-neutralization liquid and an oxidation-neutralization residue.

(6) A sixth invention of the present invention is a method for treating an alloy according to any one of the first to fifth inventions, wherein the alloy includes an alloy obtained by melting a waste battery of a lithium ion battery. be.

According to the present invention, nickel and/or cobalt can be efficiently and selectively leached from an alloy containing nickel and/or cobalt and copper such as a waste lithium ion battery, and nickel and/or cobalt can be leached. Solutions with high concentrations can be obtained.

It is a process drawing which shows an example of the flow of the processing method of an alloy.

Specific embodiments of the present invention (hereinafter referred to as "present embodiments") will be described in detail below. It should be noted that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the purpose of the present invention. In this specification, the notation "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

The alloy treatment method according to the present embodiment is a method of obtaining a solution containing nickel and/or cobalt from an alloy containing nickel and/or cobalt and copper.

Alloys containing nickel and/or cobalt and copper to be treated include, for example, waste due to deterioration of automobiles and electronic devices, lithium-ion battery scrap generated along with the life of lithium-ion batteries, or A waste battery or the like such as a defective product in the battery manufacturing process can be used. Alternatively, an alloy obtained by subjecting such a waste battery or the like to a dry treatment and heat-melting (melting) to reduce it can be used.

Below, the case where an alloy (an alloy containing nickel and/or cobalt and copper) obtained by melting waste lithium ion batteries (hereinafter also referred to as "waste lithium ion batteries") is treated. By way of example, the method of processing the alloy will be described in more detail.

FIG. 1 is a process diagram showing an example of the flow of the alloy treatment method according to the present embodiment. This method comprises a leaching step S1 in which an alloy containing nickel and/or cobalt and copper is subjected to leaching treatment with an acid solution in the presence of a sulfiding agent to obtain a leaching solution and a leaching residue, and the resulting leaching solution. A reduction step S2 in which a reducing agent is added to the reduced solution to obtain a post-reduction solution and a reduction residue, and a neutralizing agent and an oxidizing agent are added to the obtained reduced solution to neutralize the oxidation. and an oxidation-neutralization step S3 in which a post-oxidation-neutralization liquid and an oxidation-neutralization residue are obtained by treatment.

In particular, in the method according to the present embodiment, in the leaching step S1, the initial concentration of the slurry containing the alloy is adjusted to a specific range, specifically a range of 100 g / L or more and 250 g / L or less, and the leaching process is performed. It is characterized by As a result, nickel and/or cobalt can be efficiently leached, and a solution containing nickel and/or cobalt at a high concentration can be obtained.

Also, preferably, in the leaching step S1, the leaching process is performed while controlling the oxidation-reduction potential (ORP) to 200 mV or less using a silver/silver chloride electrode as a reference electrode. As a result, the formation of an oxide film (passivation film) on the alloy surface can be suppressed, and nickel and/or cobalt can be leached out more selectively.

Also, preferably, in the leaching step S1, the coexisting amount of the sulfiding agent is set to a specific range, that is, 1.05 to 1.25 equivalents (S-mol/Cu-mol) with respect to the amount of copper contained in the alloy. Leaching treatment is performed by adding an amount within the range and allowing them to coexist. As a result, nickel and/or cobalt can be leached more efficiently and easily in a short time, and a solution containing nickel and/or cobalt at a high concentration can be obtained.

(1) Leaching process [About leaching]
In the leaching step S1, an alloy containing nickel and/or cobalt and copper (hereinafter also simply referred to as "alloy") is subjected to acid leaching treatment. At this time, a sulfiding agent is added before the alloy is brought into contact with the acid, or at the same time as the alloy is brought into contact with the acid, and the leaching treatment is performed under the condition that the sulfiding agent coexists. By such a leaching treatment, a leaching solution in which nickel and/or cobalt are dissolved and a leaching residue mainly containing copper sulfide are obtained.

Reactions that occur in the leaching process in the leaching step S1 are shown in reaction formulas [1] to [5] below. The formula below shows the case where solid sulfur (S) is used as the sulfurizing agent and sulfuric acid is used as the acid.
・Cu+S → CuS [1]
・Ni+ _H2SO4 +1 _{/ 2O2} → _NiSO4 + _H2O [2]
- Co+ _H2SO4 +1 _{/ 2O2-} > _CoSO4 + _H2O [3]
・_H2S +1/ _2O2 →S+ _H2O [4]
・CuS+2O ₂ →CuSO ₄ [5]

By subjecting the alloy to a leaching treatment in the presence of an acid and a sulfiding agent, the copper leached from the alloy reacts with the sulfiding agent and precipitates in the form of copper sulfide (reaction formula [1]). . The precipitated copper sulfide is recovered as a leaching residue. On the other hand, by leaching treatment using an acid, nickel and/or cobalt constituting the alloy are leached into a solution, and a leaching solution in which nickel and cobalt are present as ions can be obtained (reaction formulas [2], [3 ]). In this way, copper and nickel and/or cobalt can be separated from the alloy.

Even when the leached nickel and/or cobalt reacts with the sulfiding agent and becomes sulfide, the sulfide is decomposed due to the presence of the acid solution, and nickel and cobalt are present in the leachate as ions. It will be. In addition, a part of the copper that did not react with the sulfiding agent may remain in the leachate, but the copper remaining in the leachate is effectively and efficiently separated and removed in the reduction step S2 described later. be able to.

[Regarding alloys to be treated]
Alloys to be treated, that is, alloys obtained by melting waste lithium-ion batteries, include alloys cast into plates, alloys that are drawn into a wire shape and cut appropriately into rods, and powdered alloys (hereinafter referred to as powders). (Alloy powder is also referred to as "alloy powder"), and the shape is not particularly limited. Among them, it is preferable to treat powdery alloy powder, because the leaching treatment can be performed more effectively and efficiently.

Moreover, when alloy powder is used, the leaching treatment can be performed more effectively if the particle size is approximately 300 μm or less. On the other hand, if the grain size of the alloy powder is too small, it is costly and may cause dust generation or ignition.

In the leaching process, it is preferable to pre-clean the alloy to be treated with a dilute acid beforehand. Thereby, activation treatment can be applied to the surface of the alloy, and the leaching reaction can be promoted.

In the leaching treatment, pure water or the like is added to the alloy to be treated to make a slurry, and an acid solution is added to the slurry containing the alloy for treatment. The sulfiding agent is added to the slurry containing the alloy so that it coexists.

[About the acid solution]
The acid solution used for the leaching treatment is not particularly limited, and mineral acids such as sulfuric acid, hydrochloric acid and nitric acid can be used. A mixed solution of these mineral acids may also be used. Furthermore, an acid solution containing chloride in sulfuric acid, for example, may be used. Among them, when the alloy to be processed is derived from waste lithium-ion batteries, the so-called "battery-to-battery" is an ideal recycling method that recycles the waste lithium-ion batteries and supplies them again as raw materials for lithium-ion batteries. In order to achieve the above, it is preferable to use acids including sulfuric acid. By using sulfuric acid, the leachate can be obtained in the form of a sulfate that can be easily used as a positive electrode material for lithium ion batteries.

In addition, the acid solution to be added leaches out the nickel and/or cobalt contained in the alloy to produce salts of nickel and cobalt, but the margin (extra) liberation used for the driving force to speed up the leaching reaction. Since an acid (for example, "free sulfuric acid" when a sulfuric acid solution is used) is also required, an amount exceeding 1 equivalent and 1.2 equivalents or less is required.

In the leaching process, the acid solution and the alloy may be supplied to a device such as a thickener in which a plurality of stages of mixing sections are connected, so that the acid and the alloy are brought into contact with each other step by step in a countercurrent flow. For example, the alloy is supplied to the uppermost mixing section of the apparatus and the acid is supplied to the lowermost mixing section of the apparatus so that the acid and the alloy are brought into stepwise contact in countercurrent flow.

[About the sulfiding agent]
Sodium hydrosulfide and elemental sulfur can be used as the sulfurizing agent added together with the acid. When elemental sulfur is used, it is preferable to pulverize it moderately so that the reaction proceeds easily.

Here, in the method according to the present embodiment, the sulfiding agent is preferably added in the range of 1.05 to 1.25 equivalents (S-mol/Cu-mol) with respect to the amount of copper contained in the alloy. It is added so that the amount is the same, and the leaching treatment is performed while coexisting with the alloy. Thereby, the leaching rate of nickel and/or cobalt can be further improved.

The sulfiding agent is used to fix all the copper contained in the alloy as copper sulfide and to efficiently and selectively leach out nickel and cobalt. More than the equivalent (S-mol/Cu-mol) is required. In order to efficiently promote the sulfurization reaction with the sulfurizing agent, it is advantageous to increase the amount of the sulfurizing agent, so it is preferable to use 1.05 equivalents or more. On the other hand, excessive addition of the sulfiding agent may generate hydrogen sulfide gas, which is desirable to be avoided, and may increase the amount of residue and increase the trouble of handling. From these points of view, the upper limit of the amount of sulfiding agent is set to 1.25 equivalents or less.

Further, the amount of the sulfiding agent to be added is more preferably in the range of 1.15 to 1.25 equivalents (S-mol/Cu-mol) with respect to the amount of copper contained in the alloy. More preferably, the leaching treatment is performed by adding such an amount of the sulfiding agent together with the sulfiding agent, whereby the leaching rate of nickel and/or cobalt can be further improved.

[Conditions for leaching treatment]
(Slurry concentration)
The method according to the present embodiment is characterized in that the initial concentration of the slurry containing the alloy containing nickel and/or cobalt is adjusted to a specific range, and an acid solution is added to the slurry for leaching treatment. Specifically, the initial concentration of the slurry containing the alloy is adjusted to 100 g/L or more, preferably 150 g/L or more, more preferably 200 g/L or more, and the leaching treatment is performed.

As a result of studies by the present inventors, the initial concentration of the slurry containing the alloy is an important factor that affects, for example, the stirring power of the reaction equipment, the addition rate of the acid solution, the leaching time, etc. when performing the leaching treatment. I found out. In the method according to the present embodiment, nickel and/or cobalt can be efficiently leached by adjusting the initial concentration of the slurry to a specific range of 100 g/L or more and performing the leaching treatment. Thus, a solution containing nickel and/or cobalt at a high concentration can be obtained easily in a short time.

Although the upper limit of the initial concentration of the slurry is not particularly limited, it is preferably 250 g/L or less. When the slurry concentration exceeds 250 g/L, the time required for leaching becomes long, and it becomes necessary to strengthen the stirring ability and increase the amount of acid solution added in order to shorten the leaching time. If the acid concentration is too high, the acid may react violently locally to generate hydrogen gas or hydrogen sulfide gas. On the other hand, if the slurry concentration is too high, the content of the alloy will be too high, and effective stirring will not be possible in the leaching reaction, possibly reducing the leaching rate. In addition, the stirring device, the reaction vessel, and the like are likely to be worn during the reaction, leading to an increase in processing costs.

The method of slurrying the alloy containing nickel and/or cobalt to be treated and the method of adjusting the concentration are not particularly limited. can.

(pH)
In the leaching process, it is preferable to measure the pH of the obtained leaching solution and monitor and control the measured pH. As metals such as nickel and cobalt are dissolved in the acid by the leaching process, the pH increases as the acid is consumed. Therefore, it is preferable to perform the treatment while appropriately controlling the pH condition within a range in which the leaching reaction of the valuable metal is promoted.

Specifically, the pH conditions are preferably controlled so that the resulting leachate has a pH in the range of 0.8 or more and 1.6 or less. By performing the leaching treatment within these ranges, the leaching is promoted, and excessive oxidation of the precipitated copper sulfide and re-dissolution can be more effectively suppressed.

The pH can be controlled by adjusting the amount of acid added. As a standard for the amount of acid to be added until the end of the reaction, it is preferably about 1.2 equivalents with respect to the total amount of nickel and/or cobalt contained in the alloy.

(oxidation-reduction potential)
Moreover, in the leaching process, it is preferable to measure the oxidation-reduction potential (ORP) of the obtained leaching solution and monitor and control the measured ORP.

Specifically, in the method according to the present embodiment, the leaching treatment is preferably performed while controlling the ORP to be 200 mV or less using a silver/silver chloride electrode as a reference electrode.

Here, the alloy to be processed tends to form an oxide film in a solution containing an oxidizing agent or dissolved oxygen, such as leaching using an acid. When an oxide film is formed on the alloy, leaching does not proceed sufficiently even when nickel and/or cobalt to be recovered remain in the alloy, and only the ORP value of the leaching solution increases. may present. Further, the increase in ORP promotes leaching of copper, which cannot be ignored.

Therefore, in the method according to the present embodiment, while controlling the ORP within a specific range, specifically, the leaching treatment is performed while controlling the ORP to a value of 200 mV or less using a silver/silver chloride electrode as a reference electrode. is preferably applied. For example, by keeping the ORP value at 200 mV or less by suppressing the supply amount of the oxidizing agent, the formation of an oxide film (passivation film) in the alloy to be treated can be effectively suppressed. can be done.

In this way, by preferably performing the leaching treatment while maintaining the ORP lower than before, the formation of a passivation film on the alloy surface is suppressed, and more efficiently and effectively nickel and / / Alternatively, cobalt leaching can proceed. At the same time, the reaction between copper and the sulfiding agent proceeds more smoothly, copper can be efficiently fixed as sulfide, copper leaching is suppressed, and nickel and/or cobalt are more selectively leached. It becomes possible to

Although the lower limit of ORP is not particularly limited, it is preferably 50 mV or more, more preferably 100 mV or more. Excessively low ORP can slow down the nickel and/or cobalt leaching reaction. Also, nickel and/or cobalt sulfides may begin to form, resulting in recovery losses.

Specific means for controlling ORP include a method of adding an oxidizing agent. In the method according to the present embodiment, the ORP is preferably controlled to 200 mV or less, so when the ORP of the leachate rises too much, the ORP is lowered by reducing or stopping the supply of the oxidant. be able to.

Conventionally known oxidants such as oxygen, air, hydrogen peroxide, and ozone gas can be used as the oxidizing agent. For example, when a gaseous oxidant is used, the ORP of the leachate can be controlled by bubbling in the solution and adjusting the supply amount (air supply amount).

Since ORP fluctuates depending on pH and temperature, it is preferable to measure ORP, pH, and liquid temperature at the same time during the leaching process and control them so that they can be maintained within appropriate ranges at the same time.

(other conditions)
In addition, it is preferable to conduct a preliminary test and determine an appropriate range of conditions such as temperature and time in the leaching treatment. In the leaching process, the leaching solution may be bubbled with air or the like so that the reaction proceeds uniformly. Furthermore, in the leaching treatment, divalent copper ions may be added, whereby the divalent copper ions act as a catalyst to promote the leaching reaction.

[Reduction step]
In the reduction step S2, a reducing agent is added to the leaching solution obtained in the leaching treatment in the leaching step S1, and a reduction treatment is performed to obtain a reduction solution (post-reduction solution) containing nickel and/or cobalt and a reduction residue. get

In the leaching treatment, copper constituting the alloy is leached out by acid and dissolved in the solution together with nickel and/or cobalt, and a part thereof may remain in the solution without reacting with the sulfiding agent. Therefore, in the reduction step S2, a precipitate containing copper can be generated by reducing a trace amount of copper remaining in the obtained leachate, and the reduction residue containing the generated precipitate is separated by solid-liquid separation. Thus, a reducing solution containing nickel and/or cobalt from which copper is separated can be obtained. This allows selective separation of copper while maintaining a high nickel and/or cobalt leaching rate.

Although the reducing agent is not particularly limited, for example, a metal less noble than copper can be used. Among them, it is preferable to use a metal containing nickel and/or cobalt and bring the leachate into contact with the metal to reduce copper. More specifically, the metal containing nickel and/or cobalt includes nickel and/or cobalt and copper, which are objects to be treated by the method according to the present embodiment, that is, to be leached in the leaching step S1. Alloys can be used. The reducing agent is not limited to one type of component, and may be a mixture of a plurality of components.

In the method according to the present embodiment, since a solution containing nickel and/or cobalt is obtained, by using the metal containing nickel and/or cobalt to be recovered as a reducing agent, the subsequent steps It is industrially advantageous because there is no need to collect the reducing agent separately. Also, of course, the metal containing nickel and/or cobalt used as a reducing agent is oxidized and dissolved in the liquid after reduction, so that the recovery amount of nickel and/or cobalt can be increased. .

As a reducing agent, sulfides can be used in addition to the metals described above. The sulfide may be in solid, liquid, or gaseous (gaseous) form. Alternatively, it may be a mixture of sulfur and powder of the alloy to be treated by the leaching treatment described above. When sulfur is used as the reducing agent, it may be added in an amount equivalent to copper contained in the treatment liquid or alloy powder.

Further, as the reducing agent, atomized powder obtained by quenching and pulverizing the molten metal of the alloy to be treated may be used. When the alloy powder itself, which is the target of the leaching treatment, is used as the reducing agent, the powder containing nickel or cobalt in an amount equal to or greater than the equivalent amount required to reduce the copper in the leaching solution should be used. Just do it.

Regarding the conditions for the reduction treatment, it is preferable to control the pH of the resulting post-reduction solution to 1.6 or less. Moreover, the temperature of the liquid is preferably 50° C. or higher, which is the same as that of the leaching treatment. As a guideline for the end point (reaction end point) at which copper is removed, the time point at which the ORP becomes 0 mV or less can be used.

[Oxidation neutralization step]
In the method according to the present embodiment, an oxidation neutralization step S3 can be provided. In the oxidation-neutralization step S3, a neutralizing agent and an oxidizing agent are added to the reducing solution obtained through the reduction step S2 to perform an oxidation-neutralization treatment, and the post-oxidation-neutralization solution and the oxidation-neutralization residue are combined. obtain.

Thus, by performing the oxidative neutralization treatment, precipitates of impurities such as iron and phosphorus contained in the reducing solution are generated and separated, and a purified solution containing nickel and/or cobalt at a high concentration is obtained. Obtainable.

As the oxidizing agent, it is preferable to use an oxidizing agent such as hydrogen peroxide or hypochlorous acid. The addition of the oxidizing agent is preferably controlled within a predetermined range by monitoring the oxidation-reduction potential (ORP) of the solution. Specifically, an oxidizing agent is added to the solution and, for example, the ORP (using silver/silver chloride as a reference electrode) is controlled to be in the range of 380 mV to 430 mV.

Moreover, after an oxidizing agent is added to cause an oxidation reaction, a neutralizing agent is added to control the pH of the solution preferably within the range of 3.8 to 4.5. By controlling the pH within such a range and performing the neutralization treatment, at least impurities such as iron and/or phosphorus can be effectively precipitated.

Although the neutralizing agent is not particularly limited, it is preferable to use an alkali such as sodium hydroxide or potassium hydroxide.

In the oxidation-neutralizing treatment, the oxidizing agent may be added after the neutralizing agent is added to the reducing liquid, or the oxidizing agent and the neutralizing agent may be added to the reducing liquid at the same time. It is preferred to add the neutralizing agent after adding the oxidizing agent. For example, when an oxidizing agent is added to a reducing solution whose pH has become high due to the addition of a neutralizing agent, if iron is contained as an impurity, the iron is not sufficiently oxidized, resulting in Fe(OH) ₃ precipitates (iron precipitates) are no longer formed, and the separation of impurities may become insufficient.

In addition, trace impurities that could not be removed even by the oxidation-neutralization treatment may be removed by providing a step of removing them by a known technique such as a solvent extraction method or an ion-exchange method after the oxidation-neutralization step S3. good.

EXAMPLES The present invention will be more specifically described below with reference to examples, but the present invention is not limited to the following examples.

[Example 1]
(Leaching process)
Waste lithium ion batteries (waste LIB) were subjected to oxidizing roasting by heating in an oxidizing atmosphere, and then dry treatment was performed by adding a reducing agent to the obtained oxidizing roasted product, heating and melting it, and reducing it. The molten alloy obtained by reduction melting was solidified to obtain powdery alloy powder having a particle size of less than 300 μm. The obtained alloy powder was used as an alloy to be treated (an alloy containing nickel, cobalt, and copper). Table 1 below shows the composition of the alloy powder analyzed using an ICP analyzer.

Next, using the alloy powder whose composition is shown in Table 1 above, leaching with a sulfuric acid solution was performed under the conditions shown in Table 2 below.

Specifically, pure water and alloy powder were put into a 500 mL separable flask with a baffle to prepare a slurry containing the alloy. At this time, the concentration (initial concentration) of the slurry was adjusted to 200 g/L.

To the slurry of the alloy, elemental sulfur was added as a sulfiding agent so that the amount of copper contained in the alloy powder was 1.25 equivalents (S-mol/Cu-mol), and the mixture was stirred at a rotation speed of 1000 rpm. Meanwhile, the temperature was maintained at 60° C., which is the set temperature, in a water bath.

Then, a 70% sulfuric acid solution was added at a rate of 14 mL/hr, and the alloy was leached while controlling to maintain pH 1.6.

The oxidation-reduction potential (ORP) value (reference electrode: silver/silver chloride electrode) was adjusted by air bubbling at a flow rate of 0.5 L/min. The reaction end point was the point when the ORP value reached 250 mV.

The slurry after leaching was recovered, solid-liquid separation was performed by filtration using a vacuum pump, and the grades of the filtrate (leaching liquid) after leaching and the leaching residue were analyzed with an ICP analyzer.

[Example 2]
In Example 2, the treatment was carried out in the same manner as in Example 1, except that the concentration (initial concentration) of the slurry was adjusted to 100 g/L.

[Conditions and results]
Table 2 below summarizes the leaching conditions in Examples 1 and 2. Table 3 below shows the analysis results of the leachate and the leach residue for Examples 1 and 2.

As shown in the results of Table 3, in both Example 1 and Example 2, nickel and cobalt could be leached at high leaching rates. Moreover, from the results of Example 2 compared with Example 1, it was found that the concentration of nickel and cobalt in the obtained leachate can be increased by increasing the concentration of the slurry subjected to the leaching treatment.

[Example 3]
(Leaching process)
Waste lithium ion batteries (waste LIB) were subjected to oxidizing roasting by heating in an oxidizing atmosphere, and then dry treatment was performed by adding a reducing agent to the obtained oxidizing roasted product, heating and melting it, and reducing it. The molten alloy obtained by reduction melting was solidified to obtain powdery alloy powder having a particle size of less than 300 μm. The obtained alloy powder was used as an alloy to be treated (an alloy containing nickel, cobalt, and copper). Table 4 below shows the composition of the alloy powder analyzed using an ICP analyzer.

Next, using the alloy powder whose composition is shown in Table 4 above, leaching with a sulfuric acid solution was performed under the conditions shown in Table 5 below.

Specifically, pure water and alloy powder were put into a 500 mL separable flask with a baffle to prepare a slurry containing the alloy. At this time, the concentration (initial concentration) of the slurry was adjusted to 200 g/L.

To the slurry of the alloy, elemental sulfur was added as a sulfiding agent so that the amount of copper contained in the alloy powder was 1.25 equivalents (S-mol/Cu-mol), and the mixture was stirred at a rotation speed of 1000 rpm. Meanwhile, the temperature was maintained at 60° C., which is the set temperature, in a water bath.

The oxidation-reduction potential (ORP) value (reference electrode: silver/silver chloride electrode) was adjusted by air bubbling at a flow rate of 0.5 L/min using a cylindrical gas ejection tube. In addition, leaching of the alloy powder and pH adjustment were controlled by adding a 70% sulfuric acid solution at a rate of 14 mL/min to maintain pH 1.0.

In Example 3, the leaching reaction was advanced while controlling the ORP value to be kept at 200 mV or less by adjusting the air flow rate. Even if the air supply was stopped assuming that the predetermined reaction was completed, the ORP value increased slightly, but ended when it reached 250 mV.

The slurry after leaching was recovered, solid-liquid separation was performed by filtration using a vacuum pump, and the grades of the filtrate (leaching liquid) after leaching and the leaching residue were analyzed with an ICP analyzer.

[Comparative Example 1]
In Comparative Example 1, air was supplied in the same manner as in Example 3, but the ORP value was left as it was without specific control. The ORP value was maintained at approximately 250 mV even after the air supply was stopped. Other than this, the procedure was the same as in Example 3.

[Conditions and results]
Table 5 below summarizes the leaching conditions in Example 3 and Comparative Example 1. In addition, Table 6 below shows the analysis results of the leachate and the leach residue.

As shown in the results of Table 6, in Example 3 in which the leaching treatment was performed while controlling the ORP value to be maintained at 200 mV or less, the leaching of copper was suppressed and the leaching of nickel and cobalt was selectively promoted. I was able to On the other hand, in Comparative Example 1, the copper concentration in the leaching solution was as high as 16 g/L, and nickel and cobalt could not be selectively leached.

Thus, it was found that the leaching of nickel and cobalt can be promoted by controlling the ORP to be 200 mV or less. It is considered that this is because the formation of an oxide film (passivation film) on the surface of the alloy to be treated could be suppressed by controlling the ORP.

[Example 4]
(Leaching process)
Waste lithium ion batteries (waste LIB) were subjected to oxidizing roasting by heating in an oxidizing atmosphere, and then dry treatment was performed by adding a reducing agent to the obtained oxidizing roasted product, heating and melting it, and reducing it. The molten alloy obtained by reduction melting was solidified to obtain powdery alloy powder having a particle size of less than 300 μm. The obtained alloy powder was used as an alloy to be treated (an alloy containing nickel, cobalt, and copper). Table 7 below shows the composition of the alloy powder analyzed using an ICP analyzer.

Next, using the alloy powder whose composition is shown in Table 7 above, leaching with a sulfuric acid solution was performed under the conditions shown in Table 8 below.

Specifically, pure water and alloy powder were put into a 500 mL separable flask with a baffle to prepare a slurry containing the alloy. At this time, the concentration (initial concentration) of the slurry was adjusted to 200 g/L.

To the slurry of the alloy, elemental sulfur with a diameter of several millimeters was added as a sulfiding agent so that the amount of copper contained in the alloy powder was 1.05 equivalent (S-mol/Cu-mol), and the rotation speed was 1000 rpm. The mixture was heated to a set temperature of about 60° C. in a water bath and maintained while stirring at .

The oxidation-reduction potential (ORP) value (reference electrode: silver/silver chloride electrode) was adjusted by air bubbling at a flow rate of 0.5 L/min, and a 70% sulfuric acid solution was added at a rate of 14 mL/h. Then, the alloy was leached while controlling to maintain pH 1.2.

The end point of the reaction was the point when the ORP value reached 250 mV.

The slurry after leaching was recovered, solid-liquid separation was performed by filtration using a vacuum pump, and the grades of the filtrate (leaching liquid) after leaching and the leaching residue were analyzed with an ICP analyzer.

[Example 5]
In Example 5, the same amount as in Example 4 was used, except that the amount of elemental sulfur added was 1.15 equivalents (S-mol/Cu-mol) with respect to the amount of copper contained in the alloy powder. processed.

[Example 6]
In Example 6, the same amount as in Example 4 was used, except that the amount of elemental sulfur added was set to 1.25 equivalents (S-mol/Cu-mol) with respect to the amount of copper contained in the alloy powder. processed.

[Conditions and results]
Table 8 below summarizes the leaching treatment conditions in Examples 4 to 6. In addition, Table 9 shows the analysis results of the leachate and the leach residue for each of Examples 4-6.

As shown in the results in Table 9, by setting the amount of the sulfiding agent added to 1.05 to 1.25 equivalents with respect to the amount of copper contained in the alloy powder, nickel and cobalt can be efficiently leached at a high rate. was able to leach out. Among them, in Examples 5 and 6 in which the amount of the sulfurizing agent added was 1.15 equivalents or more, a sufficient amount was supplied to fix (sulfurize) the copper contained in the alloy, so nickel and cobalt were leached out by 99%. It is assumed that it has progressed to

In Examples 5 and 6 in which the amount of the sulfurizing agent added was 1.15 equivalents or more, the time required for the ORP of the leachate to reach 250 mV was longer than in Example 4 (the amount of the sulfurizing agent added was 1.05 equivalents). It was confirmed that it was shortened and could be processed more efficiently.

Claims (6)

1. A method of processing an alloy to obtain a solution containing nickel and/or cobalt from an alloy containing nickel and/or cobalt and copper, comprising:
a leaching step of subjecting the slurry containing the alloy to a leaching treatment with an acid solution in the presence of a sulfiding agent to obtain a leaching solution and a leaching residue;
In the leaching step, the initial concentration of the slurry containing the alloy is adjusted to 100 g / L or more and 250 g / L or less, and the leaching process is performed.
Alloy processing method. In the leaching step, the leaching process is performed while controlling the oxidation-reduction potential (the reference electrode is silver/silver chloride electrode) to 200 mV or less.
A method of processing an alloy according to claim 1. In the leaching step, the sulfiding agent is allowed to coexist in an amount ranging from 1.05 to 1.25 equivalents (S-mol/Cu-mol) with respect to the amount of copper contained in the alloy, and the leaching process is performed. ,
3. A method of processing an alloy according to claim 1 or 2. further comprising a reduction step of adding a reducing agent to the leachate obtained through the leaching step and performing a reduction treatment to obtain a post-reduction solution and a reduction residue;
A method of processing an alloy according to claim 1. an oxidation-neutralization step of adding a neutralizing agent and an oxidizing agent to the reducing solution obtained through the reducing step to perform an oxidation-neutralization treatment to obtain an oxidation-neutralized solution and an oxidation-neutralization residue; , further including
A method of processing an alloy according to claim 1. The alloy includes an alloy obtained by melting a waste lithium-ion battery,
A method of processing an alloy according to claim 1.

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