JP2021031760A - Process for recovering valuable metal - Google Patents

Abstract

To provide a process for recovering valuable metal at low cost.SOLUTION: Provided is a process for recovering valuable metal including the following steps: a preparation step of preparing a charge material containing at least lithium (Li) and valuable metal; an oxidation-reduction-melting step of subjecting the charge material to an oxidation treatment and a reduction-melting treatment to yield a reduction product containing a valuable metal-containing molten alloy and a slag; and a slag separation step of separating the slag from the reduction product and recovering the molten alloy, and in which the molar ratio (Li/Al ratio) of lithium (Li) to aluminum (Al) in the slag is set to 0.40 or more, and the molar ratio (Ca/Al ratio) of calcium (Ca) to aluminum (Al) in the slag is set to 0.30 or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for recovering valuable metals.

In recent years, lithium-ion batteries have become widespread as lightweight, high-power batteries. A well-known lithium-ion battery has a structure in which a negative electrode material, a positive electrode material, a separator, and an electrolytic solution are sealed in an outer can. Here, the outer can is made of a metal such as iron (Fe) or aluminum (Al). The negative electrode material is made of a negative electrode active material (graphite or the like) fixed to a negative electrode current collector (copper foil or the like). The positive electrode material is made of a positive electrode active material (lithium nickel oxide, lithium cobalt oxide, etc.) fixed to a positive electrode current collector (aluminum foil, etc.). The separator is made of a polypropylene porous resin film or the like. The electrolytic solution contains an electrolyte such as lithium hexafluorophosphate (LiPF _6).

One of the main applications of lithium-ion batteries is hybrid vehicles and electric vehicles. Therefore, it is expected that a large amount of on-board lithium-ion batteries will be discarded in the future according to the life cycle of the automobile. There are also lithium-ion batteries that are discarded as defective products during manufacturing. It is required to reuse such used batteries and defective batteries generated during manufacturing (hereinafter, “waste lithium ion batteries”) as resources.

As a method of reuse, a pyrometallurgical process in which the entire amount of waste lithium ion batteries is melted in a high-temperature furnace has been proposed. In the pyrometallurgy process, crushed waste lithium-ion batteries are melted, and valuable metals to be recovered, such as cobalt (Co), nickel (Ni) and copper (Cu), and iron (Fe) and aluminum (Fe) and aluminum ( This is a method for separating and recovering low-value-added metals such as Al) by utilizing the difference in oxygen affinity between them. In this method, low-value-added metals are oxidized as much as possible to form slag, while valuable metals are recovered as alloys by suppressing their oxidation as much as possible.

For example, Patent Document 1 is a process of recovering enthalpy and metal from a lithium ion battery in a copper smelting furnace, which comprises a step of supplying a useful feed material and a slag forming agent to the smelting furnace, and a heating agent and a reducing agent. Is included, and at least a part of the heating agent and / or reducing agent is replaced with a lithium ion battery containing one or more of metallic iron, metallic aluminum, and carbon. , The process is disclosed (claim 1 of Patent Document 1). If a copper smelting furnace can be used, valuable metals such as copper and nickel can be efficiently recovered from the lithium-ion battery in accordance with copper smelting. Cobalt is distributed to slag in copper smelting. In order to recover cobalt, for example, a method of roasting a waste lithium ion battery to separate the alloy and slag and wet-treating the obtained alloy can be considered.

Patent Document 2 is a valuable metal recovery method for recovering a valuable metal containing nickel and the cobalt from a waste battery of a lithium ion battery containing nickel and cobalt, and melts the waste battery to obtain a melt. Slag is formed from the melting step, the oxidation step performed on the molten material at the time of the melting step, or the waste battery before the melting step, and oxidizing the waste battery, and the melt. It includes a slag separation step of separating and recovering an alloy containing a valuable metal, and a dephosphorization step of separating phosphorus contained in the alloy. The dephosphorization step adds a lime-containing substance to the alloy. Next, a method for recovering valuable metals, which is a step of oxidizing the alloy, is disclosed (claim 1 of Patent Document 2). _{Patent Document 2 proposes a process of recovering valuable metals by adding silicon dioxide (SiO 2} ) and calcium oxide (CaO) to lower the melting point of slag when melting a waste lithium ion battery ((SiO 2). Patent Document 2 [0037] and [0038]).

International Publication No. 2015/096945 Japanese Patent No. 5835585

However, there are still problems with the methods proposed in Patent Document 1 and Patent Document 2. For example, the method of Patent Document 1 requires high temperature treatment. In addition, there is a problem that the oxide of the processing container is eroded by the slag and immediately cracked. If such erosion occurs, the equipment cost becomes enormous and valuable metals cannot be recovered at low cost. In the method disclosed in Patent Document 2, since the amount of flux added is large, the amount of waste lithium ion battery processed is small. Further, since the flux contains a large amount of silicon dioxide (SiO ₂ ) which is an acidic oxide, it may be insufficient to remove phosphorus which becomes an acidic oxide from the metal. Due to such problems, it is desired to develop a technique for inexpensively recovering valuable metals from waste lithium ion batteries.

The present inventors have conducted diligent studies in view of such circumstances. As a result, we focused on the molar ratio of lithium (Li) to aluminum (Al) in the slag (Li / Al ratio) and the molar ratio of calcium (Ca) to aluminum (Al) (Ca / Al ratio). It was found that by limiting the ratio within a predetermined range, the melting temperature of slag can be lowered to a low temperature of 1550 ° C. or lower, and valuable metals can be recovered at low cost.

The present invention has been completed based on such findings, and an object of the present invention is to provide a method capable of recovering valuable metals at low cost.

The present invention includes the following aspects (1) to (7). In addition, in this specification, the expression "~" includes the numerical values at both ends thereof. That is, "X to Y" is synonymous with "X or more and Y or less".

(1) A method for recovering valuable metals in the following steps:
A preparatory step to prepare a charge containing at least lithium (Li) and a valuable metal,
An oxidation-reduction melting step of subjecting the charged material to an oxidation treatment and a reduction melting treatment to obtain a reduced product containing a fusion metal containing a valuable metal and slag.
The slag separation step of separating the slag from the reduced product and recovering the fused gold is included.
The molar ratio of lithium (Li) to aluminum (Al) in the slag (Li / Al ratio) is 0.40 or more, and the molar ratio of calcium (Ca) to aluminum (Al) in the slag (Ca / Al ratio). ) Is 0.30 or more.

(2) The method according to (1) above, wherein a flux containing calcium (Ca) is added to the charged material and / or the processed material in either one or both of the preparation step and the redox melting step.

(3) The above (1) or the above (1) or the above (1) or the above (1) or Method (2).

(4) The method according to any one of (1) to (3) above, wherein a reducing agent is introduced during the reduction melting treatment.

(5) The method according to any one of (1) to (4) above, wherein the heating temperature of the reduction melting treatment is 1300 ° C. or higher and 1550 ° C. or lower.

(6) The method of (5) above, wherein the heating temperature of the reduction melting treatment is 1350 ° C. or higher and 1450 ° C. or lower.

(7) The method according to any one of (1) to (6) above, wherein the charge includes a waste lithium ion battery.

According to the present invention, there is provided a method capable of recovering valuable metals at low cost.

An example of a method for recovering valuable metals is shown.

A specific embodiment of the present invention (hereinafter, referred to as “the present embodiment”) will be described. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention.

1. 1. Method of recovering valuable metal The method of recovering the valuable metal of the present embodiment is as follows: the following steps: a preparatory step of preparing a charge containing at least lithium (Li) and the valuable metal, and an oxidation treatment and reduction of the charge. It includes an oxidation-reduction melting step of performing a melting treatment to obtain a reduced product containing a fused metal containing a valuable metal and slag, and a slag separation step of separating slag from the reduced product and recovering the fused gold. Further, the molar ratio (Li / Al ratio) of lithium (Li) to aluminum (Al) in the slag is set to 0.40 or more, and the molar ratio of calcium (Ca) to aluminum (Al) in the slag (Ca / Al ratio). Is 0.30 or more.

The present embodiment is a method of recovering a valuable metal from a charge containing at least lithium (Li) and a valuable metal. Here, the valuable metal is to be recovered, and is at least one kind of metal or alloy selected from the group consisting of copper (Cu), nickel (Ni), cobalt (Co) and combinations thereof. Further, the present embodiment is mainly a recovery method by a pyrometallurgical process. However, it may consist of a pyrometallurgical process and a hydrometallurgical process. Details of each step will be described below.

<Preparation process>
In the preparation process, the charge is prepared. The charge is to be treated for recovering valuable metals, contains lithium (Li), and is further selected from the group consisting of copper (Cu), nickel (Ni), cobalt (Co), and combinations thereof. Contains at least one valuable metal. The charge may contain these components (Li, Cu, Ni, Co) in the form of a metal or a compound such as an oxide. Further, the charged material may contain other inorganic components and organic components other than these components (Li, Cu, Ni, Co).

The target of the charged material is not particularly limited, and examples thereof include waste lithium ion batteries, dielectric materials (capacitors), and magnetic materials. Further, the form is not limited as long as it is suitable for the treatment in the subsequent redox melting step. In the preparatory step, the charged material may be subjected to a treatment such as crushing treatment to obtain a suitable form. Further, in the preparatory step, the charged material may be subjected to a treatment such as a heat treatment or a sorting treatment to remove unnecessary components such as water and organic substances.

<Redox melting process>
In the redox melting step, the prepared charge is subjected to an oxidation treatment and a reduction melting treatment to obtain a reduced product. This reduced product contains the fused metal and the slag separately. The fused gold contains a valuable metal. Therefore, it is possible to separate the component containing a valuable metal (fused gold) and other components in the reduced product. This is because metals with low added value (Al, etc.) have high oxygen affinity, whereas valuable metals have low oxygen affinity. For example, aluminum (Al), lithium (Li), carbon (C), manganese (Mn), phosphorus (P), iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu) are generally used. It is oxidized in the order of Al>Li>C>Mn>P>Fe>Co>Ni> Cu. That is, aluminum (Al) is most easily oxidized, and copper (Cu) is least easily oxidized. Therefore, low-value-added metals (Al and the like) are easily oxidized to slag, and valuable metals (Cu, Ni, Co) are reduced to become molten metals (alloys). In this way, the metal having low added value and the valuable metal can be separated into the slag and the fused metal.

In the present embodiment, the molar ratio (Li / Al ratio) of lithium (Li) to aluminum (Al) in the slag is 0.40 or more, and the molar ratio of calcium (Ca) to aluminum (Al) (Ca / Al ratio). Is 0.30 or more. Lithium (Li) and calcium (Ca) contribute to lowering the melting temperature of slag. Therefore, by controlling the slag component within the above range, the melting temperature of the slag can be set to 1550 ° C. or lower, for example, 1450 ° C. or lower. Further, when the amount of calcium (Ca) in the slag is large, it becomes easy to remove this phosphorus when the charge contains phosphorus. This is because when phosphorus is oxidized, it becomes an acidic oxide, whereas when calcium (Ca) is oxidized, it becomes a basic oxide. The higher the amount of calcium (Ca) in the slag, the more basic the slag composition becomes, and as a result, it becomes easier to contain phosphorus in the slag and remove it.

From the viewpoint of the slag melting temperature, the upper limits of the Li / Al ratio and the Ca / Al ratio are not particularly limited. The slag does not have to contain aluminum (Al). For example, lithium oxide (Li ₂ O) alone can be melted at about 1430 ° C. However, if the Li / Al ratio is excessively high, the life of the crucible may be shortened depending on the material of the crucible used. Further, when both the Li / Al ratio and the Ca / Al ratio are excessively high, the slag may be difficult to melt. The Li / Al ratio in the slag is preferably 0.40 or more and 10.00 or less, and more preferably 0.40 or more and 2.50 or less. The Ca / Al ratio is preferably 0.30 or more and 3.00 or less, and more preferably 0.30 or more and 1.00 or less. The amount of the slag component (Al, Li, Ca) can be easily controlled by adjusting the composition of the charged material and the amount of flux added, which will be described later.

A flux containing calcium (Ca) may be added to the treated product to adjust the amount of calcium (Ca) in the slag. The flux preferably contains calcium (Ca) as a main component, and examples thereof include calcium oxide (CaO) and calcium carbonate (CaCO ₃ ). Further, the flux may be added at a stage before the reduction melting treatment step. That is, flux may be added to the charged material and / or the processed material in one or both of the preparation step and / or the redox melting step (oxidation treatment, reduction melting treatment). However, if the charge itself contains a large amount of calcium (Ca) component, it is not necessary to add the flux. Further, the flux preferably does not contain silicon (Si).

In the redox melting step, the oxidation treatment and the reduction melting treatment may be performed at the same time or separately. As a method to be performed at the same time, there is a method of injecting an oxidizing agent into the melt obtained by the reduction melting treatment. Specifically, a metal tube (lance) may be inserted into the melt, and an oxidizing agent may be blown by bubbling. In this case, a gas containing oxygen such as air, pure oxygen, and oxygen-enriched gas can be used as the oxidizing agent. However, it is preferable that the redox melting step includes the oxidation roasting step and the reduction melting step separately. As such a method, during the oxidation treatment, the prepared charge is oxidatively roasted to obtain an oxidative roasted product, and during the reduction melting treatment, the obtained oxidative roasted product is reduced and melted to obtain a reduced product. The method can be mentioned. The details of the oxidative roasting step and the reduction melting step will be described below.

<Oxidation roasting process>
The oxidative roasting step is a step of oxidatively roasting (oxidizing treatment) the charged material to obtain an oxidative roasted product. By providing the oxidative roasting step, even if the charged material contains carbon, the carbon can be oxidized and removed, and as a result, the alloy integration of the valuable metal in the subsequent reduction melting step can be promoted. .. That is, in the reduction melting step, the valuable metal is reduced to local molten fine particles. Carbon becomes a physical obstacle when molten fine particles (valuable metals) agglomerate. Therefore, if the oxidative roasting step is not provided, carbon hinders the agglutination and integration of the molten fine particles and the resulting separability of the metal (fused metal) and the slag, which may reduce the valuable metal recovery rate. On the other hand, by removing carbon in the oxidative roasting process in advance, the coagulation and integration of the molten fine particles (valuable metal) in the reduction melting process progresses, and the recovery rate of the valuable metal is further increased. Is possible.

Moreover, by providing the oxidation roasting step, it is possible to suppress the variation in oxidation. In the oxidative roasting step, it is desirable to perform treatment (oxidative roasting) at an oxidation degree capable of oxidizing a metal (Al or the like) having a low added value contained in the charged material. On the other hand, the degree of oxidation can be easily controlled by adjusting the processing temperature, time and / or atmosphere of oxidative roasting. Therefore, the degree of oxidation can be adjusted more strictly by the oxidation roasting step, and the variation in oxidation can be suppressed.

The degree of oxidation is adjusted as follows. As mentioned above, aluminum (Al), lithium (Li), carbon (C), manganese (Mn), phosphorus (P), iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu) are Generally, it is oxidized in the order of Al> Li> C> Mn> P> Fe> Co> Ni> Cu. In the oxidation roasting step, the oxidation proceeds until the entire amount of aluminum (Al) is oxidized. Oxidation may be promoted until a part of iron (Fe) is oxidized, but the degree of oxidation is maintained to such an extent that cobalt (Co) is not oxidized and recovered as slag.

When adjusting the degree of oxidation in the oxidation roasting step, it is preferable to introduce an appropriate amount of an oxidizing agent. In particular, when the charged material contains a waste lithium ion battery, it is preferable to introduce an oxidizing agent. Lithium-ion batteries contain metals such as aluminum and iron as exterior materials. It also contains aluminum foil and carbon material as the positive electrode material and the negative electrode material. Furthermore, in the case of collective batteries, plastic is used as an external package. All of these are materials that act as reducing agents. By introducing an oxidizing agent, the degree of oxidation in the oxidative roasting process can be adjusted within an appropriate range.

The oxidizing agent is not particularly limited as long as it can oxidize carbon or a metal having low added value (Al or the like). However, oxygen-containing gases such as air, pure oxygen, and oxygen-enriched gas, which are easy to handle, are preferable. As a guide, the amount of the oxidizing agent introduced is about 1.2 times (for example, 1.15 to 1.25 times) the amount (chemical equivalent) required for oxidation of each substance to be oxidized.

The heating temperature for oxidative roasting (oxidation treatment) is preferably 700 ° C. or higher and 1100 ° C. or lower, and more preferably 800 ° C. or higher and 1000 ° C. or lower. At 700 ° C. or higher, the carbon oxidation efficiency can be further increased and the oxidation time can be shortened. Further, at 1100 ° C. or lower, the thermal energy cost can be suppressed and the efficiency of oxidative roasting can be improved.

Oxidation roasting (oxidation treatment) can be performed using a known roasting furnace. Further, it is preferable to use a furnace (preliminary furnace) different from the melting furnace used in the subsequent reduction melting step and perform the process in the preliminary furnace. As the roasting furnace, any type of furnace can be used as long as it is a furnace capable of supplying an oxidizing agent (oxygen or the like) while roasting the charged material and performing an oxidation treatment inside the furnace. As an example, a conventionally known rotary kiln and tunnel kiln (Haas furnace) can be mentioned.

<Reduction melting process>
The reduction melting step is a step of heating the obtained oxidized roasted product to reduce and melt it to obtain a reduced product. The purpose of this step is to maintain the low value-added metals (Al, etc.) oxidized in the oxidation roasting step as oxides, while reducing and melting the oxidized valuable metals (Cu, Ni, Co). It is to recover as a converted alloy. The material obtained after the reduction treatment is called a "reduced product", and the alloy obtained as a melt is called a "fused gold".

It is preferable to introduce a reducing agent during the reduction melting treatment. Further, it is preferable to use carbon and / or carbon monoxide as the reducing agent. Carbon has the ability to easily reduce valuable metals (Cu, Ni, Co) to be recovered. For example, 1 mol of carbon can reduce 2 mol of valuable metal oxides (copper oxide, nickel oxide, etc.). Further, the reduction method using carbon or carbon monoxide is extremely safer than the method using a metal reducing agent (for example, the thermite reaction method using aluminum). Artificial graphite and / or natural graphite can be used as carbon, and coal or coke can be used if there is no risk of impurity contamination.

The heating temperature of the reduction melting treatment is not particularly limited. However, the heating temperature is preferably 1300 ° C. or higher and 1550 ° C. or lower, and more preferably 1350 ° C. or higher and 1450 ° C. or lower. At temperatures above 1550 ° C., thermal energy is wasted, and refractories such as crucibles are heavily consumed, which may reduce productivity. On the other hand, if the temperature is less than 1300 ° C., there is a problem that the separability of the slag and the fused metal deteriorates and the recovery rate decreases. The reduction melting treatment may be carried out by a known method. For example, a method of charging an oxidized roasted product into an alumina (Al ₂ O ₃ ) crucible and heating it by resistance heating or the like can be mentioned. In addition, harmful substances such as dust and exhaust gas may be generated during the reduction melting treatment, but the harmful substances can be detoxified by performing a treatment such as a known exhaust gas treatment.

When the oxidation roasting step is provided, it is not necessary to perform the oxidation treatment in the reduction melting step. However, if the oxidation in the oxidation roasting step is insufficient, or if the purpose is to further adjust the degree of oxidation, an additional oxidation treatment may be performed in the reduction melting step. By performing an additional oxidation treatment, it is possible to adjust the degree of oxidation more strictly.

<Slag separation process>
In the slag separation step, the slag is separated from the reduced product obtained in the redox melting step, and the fused gold is recovered. Slag and fused gold have different specific gravities. Therefore, the slag having a smaller specific gravity than the fused metal collects on the upper part of the fused metal, and can be separated and recovered by the specific gravity separation.

After the slag separation step, a sulfurization step of sulfurizing the obtained alloy or a pulverization step of pulverizing a mixture of the obtained sulfide and the alloy may be provided. Further, a hydrometallurgical process may be performed on the valuable metal alloy obtained through such a pyrometallurgical process. Impurity components can be removed, valuable metals (Cu, Ni, Co) can be separated and purified by a hydrometallurgy process, and each can be recovered. Examples of the treatment in the hydrometallurgy process include known methods such as neutralization treatment and solvent extraction treatment.

According to the method of this embodiment, the melting temperature of the slag is 1550 ° C. or lower, for example, 1450 ° C. or lower, and the slag becomes less viscous. Therefore, the slag and the fused metal can be efficiently separated in the slag separation step, and as a result, the valuable metal can be efficiently and inexpensively recovered.

2. Recovery from Waste Lithium Ion Battery The charge of this embodiment is not limited as long as it contains lithium (Li) and a valuable metal. However, the charge preferably contains a waste lithium ion battery. The waste lithium ion battery contains lithium (Li) and valuable metals (Cu, Ni, Co), and also contains low-value-added metals (Al, Fe) and carbon components. Therefore, by using a waste lithium ion battery as a charge, valuable metals can be efficiently separated and recovered. The waste lithium-ion battery is not only a used lithium-ion battery, but also a lithium-ion battery such as defective products generated in the manufacturing process of the positive electrode material constituting the battery, residues inside the manufacturing process, and generated waste. It is a concept that includes waste materials in the process. Therefore, the waste lithium-ion battery can also be called a lithium-ion battery waste material.

A method of recovering valuable metals from a waste lithium ion battery will be described with reference to FIG. FIG. 1 is a process diagram showing an example of a recovery method. As shown in FIG. 1, this method includes a waste battery pretreatment step (S1) for removing an electrolytic solution and an outer can of a waste lithium ion battery, and a first method of crushing the contents of the waste battery into a crushed product. It has a crushing step (S2), an oxidative roasting step (S3) in which the crushed product is oxidatively roasted, and a reduction melting step (S4) in which the oxidative roasted product is reduced and melted to form an alloy. Further, although not shown, a sulfurization step of sulfurizing the obtained alloy and a second grinding step of pulverizing the mixture of the obtained sulfide and the alloy may be provided after the reduction melting step (S4). .. Details of each step will be described below.

<Waste battery pretreatment process>
The waste battery pretreatment step (S1) is performed for the purpose of preventing the waste lithium ion battery from exploding, detoxifying it, and removing the outer can. Since the lithium ion battery is a closed system, it has an electrolytic solution and the like inside. Therefore, if the crushing process is performed as it is, there is a risk of explosion, which is dangerous. It is preferable to perform a discharge treatment or an electrolytic solution removal treatment by some method. Further, the outer can is often composed of metal aluminum (Al) or iron (Fe), and it is relatively easy to recover the metal outer can as it is. By removing the electrolytic solution and the outer can in the waste battery pretreatment step (S1) in this way, it is possible to improve the safety and the recovery rate of valuable metals (Cu, Ni, Co).

The specific method of waste battery pretreatment is not particularly limited. For example, a method of physically opening a waste battery with a needle-shaped cutting edge to remove an electrolytic solution can be mentioned. Another method is to heat the waste battery and burn the electrolytic solution to make it harmless.

When recovering aluminum (Al) and iron (Fe) contained in the outer can in the waste battery pretreatment step (S1), the removed outer can is crushed and then the crushed material is sieved using a sieve. It may be sieved. Since aluminum (Al) is easily powdered by light pulverization, it can be efficiently recovered. Further, iron (Fe) contained in the outer can may be recovered by magnetic force sorting.

<First crushing process>
In the first pulverization step (S2), the contents of the waste lithium ion battery are pulverized to obtain a pulverized product. This process aims to increase the reaction efficiency in the pyrometallurgical process. By increasing the reaction efficiency, the recovery rate of valuable metals (Cu, Ni, Co) can be increased. The specific pulverization method is not particularly limited. It can be crushed using a conventionally known crusher such as a cutter mixer. The waste battery pretreatment step and the first crushing step together correspond to the preparatory steps described above.

<Oxidation roasting process>
In the oxidative roasting step (S3), the pulverized product obtained in the first pulverization step (S2) is oxidatively roasted to obtain an oxidative roasted product. The details of this process are as described above.

<Reduction melting process>
In the reduction melting step (S4), the oxidative roasted product obtained in the oxidative roasting step (S3) is reduced to obtain a reduced product. The details of this process are as described above.

<Slag separation process>
In the slag separation step, the slag is separated from the reduced product obtained in the reduction melting step (S4), and the molten metal is recovered. The details of this process are as described above.

A sulfurization step or a pulverization step may be provided after the slag separation step. Further, a wet smelting process may be performed on the obtained valuable metal alloy. The details of the sulfurization step, the pulverization step and the hydrometallurgy process are as described above.

The present invention will be described in more detail with reference to the following examples and comparative examples. However, the present invention is not limited to the following examples.

Example 1
(1) Recovery of valuable metals Valuable metals were recovered using a waste lithium-ion battery as a charge. Recovery was carried out according to the following steps.

<Waste battery pretreatment process (preparation process)>
As waste lithium-ion batteries, 18650-inch cylindrical batteries, used square batteries for vehicles, and defective products collected in the battery manufacturing process were prepared. After immersing these waste batteries in salt water and discharging them, the water content was removed, and the waste batteries were roasted in the air at 260 ° C. to decompose and remove the electrolytic solution and the outer can to obtain the battery contents.

<First crushing process (preparation process)>
The obtained battery contents were crushed using a crusher (Ujiie Seisakusho Co., Ltd., Good Cutter) to prepare a charge.

<Oxidation roasting process>
The obtained crushed product (charged material) was oxidatively roasted to obtain an oxidative roasted product. Oxidative roasting was carried out using a rotary kiln at 900 ° C. in the air for 180 minutes.

<Reduction melting process>
Graphite is added as a reducing agent to the obtained oxidized roasted product in an amount of 0.6 times the total number of moles of valuable metals (Cu, Ni, Co), and calcium oxide (CaO) is added as a flux in a Ca / Al ratio. Was added and mixed so as to have a value of 0.33, and the obtained mixture was charged into an _{alumina (Al 2} O _{3) crucible.} Then, the mixture charged in the crucible was heated and subjected to a reduction melting treatment to alloy it, and a reduced product containing a fusion metal and slag was obtained. The reduction melting treatment was carried out by resistance heating at 1400 ° C. for 60 minutes.

<Slag separation process>
The slag was separated from the obtained reduced product, and the fused metal was recovered to obtain a recovered alloy.

(2) Evaluation <Analysis of slag components>
The component analysis of the slag separated from the reduced product was performed as follows. That is, the obtained slag was cooled and then pulverized, and analyzed by fluorescent X-ray.

<Valuable metal recovery rate>
The valuable metal (Co) recovery rate was determined as follows. That is, it was calculated as (Co weight in the recovered alloy) ÷ (Co weight in the recovered alloy + Co weight in the slag) × 100 (mass%). The component analysis in the recovered alloy was performed by fluorescent X-ray.

Example 2 to Example 8
Same as Example 1 except that the ratio of 18650 type cylindrical battery, used square battery and defective product prepared in the waste battery pretreatment step was changed and the melting temperature in the reduction melting treatment step was set to the temperature shown in Table 1. The valuable metal was recovered and evaluated.

(3) Results Table 1 shows the results obtained for Examples 1 to 8. Examples 1 to 6 are examples, and examples 7 and 8 are comparative examples.

In Examples 1 to 6, the separability of the slag and the metal (fused metal) was good. Further, as shown in Table 1, the cobalt (Co) recovery rate was as good as 95% or more. On the other hand, in Comparative Examples 7 and 8, the cobalt recovery rate was lower than that in Examples. In Example 7 and Example 8, it was presumed that the viscosity of the slag increased because the slag could not be completely melted. That is, it was considered that the increased viscosity of the slag caused a large number of metal particles to be present in the recovered slag, which led to a deterioration in the separability between the slag and the metal, that is, a deterioration in the cobalt recovery rate. The recovery rates of copper (Cu) and nickel (Ni) exceeded 95% in all cases.

Claims (7)

It is a method of recovering valuable metals, and the following steps:
A preparatory step to prepare a charge containing at least lithium (Li) and a valuable metal,
An oxidation-reduction melting step of subjecting the charged material to an oxidation treatment and a reduction melting treatment to obtain a reduced product containing a fusion metal containing a valuable metal and slag.
The slag separation step of separating the slag from the reduced product and recovering the fused gold is included.
The molar ratio of lithium (Li) to aluminum (Al) in the slag (Li / Al ratio) is 0.40 or more, and the molar ratio of calcium (Ca) to aluminum (Al) in the slag (Ca / Al ratio). ) Is 0.30 or more. The method according to claim 1, wherein a flux containing calcium (Ca) is added to the charged material and / or the processed material in either one or both of the preparation step and the redox melting step. The invention according to claim 1 or 2, wherein the charged material is oxidatively roasted to obtain an oxidative roasted product during the oxidation treatment, and the oxidative roasted product is reduced and melted to obtain a reduced product during the reduction melting treatment. Method. The method according to any one of claims 1 to 3, wherein a reducing agent is introduced during the reduction melting treatment. The method according to any one of claims 1 to 4, wherein the heating temperature of the reduction melting treatment is 1300 ° C. or higher and 1550 ° C. or lower. The method according to claim 5, wherein the heating temperature of the reduction melting treatment is 1350 ° C. or higher and 1450 ° C. or lower. The method according to any one of claims 1 to 6, wherein the charge includes a waste lithium ion battery.

Images