JP2018100452A - Dissolution method of scrap, and metal recovery method using dissolution method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dissolution method of scrap capable of dissolving scrap effectively; and to provide a metal recovery method from scrap by using the method.SOLUTION: There is provided a method for dissolving scrap of a metal or a metal oxide. In the dissolution method of scrap, when performing acid leach with mineral acid, a compound of a transition metal which is less noble than all the leaching object metals is added, and the leaching object metals are dissolved into leaching liquid as much as 90 wt% or more to the amount contained in the scrap, and the compound of the transition metal becomes insoluble.SELECTED DRAWING: None

Description

  The present invention relates to a scrap melting method and a metal recovery method using the melting method.

  It is very common to use chemical dissolution treatment with acids to recover metals from metals and metal compounds. In this case, in order to increase the metal recovery rate, it is required to dissolve as much metal as possible, preferably the entire amount of metal. Therefore, it is necessary to devise such as using an acid several times the theoretical equivalent amount under strong acid, or adding an auxiliary agent such as hydrogen peroxide solution for leveling the potential (ORP).

  For example, the technique described in Patent Document 1 discloses a technique for efficiently recovering cobalt from lithium cobaltate, which is a substance that represents a positive electrode active material for a lithium ion secondary battery. According to this technique, lithium ion secondary is obtained by using sulfuric acid diluted by a ratio of 1.47 to 1.67 for sulfuric acid and 0.67 to 4.0 for water with respect to 1 lithium cobaltate by weight ratio. The positive electrode active material for a battery is dissolved, the solution is kept at 60 ° C. or higher, hydrogen peroxide is added to lower the potential, and sulfuric acid is added thereto to adjust the pH to 0.4 to 0.8. Adjust and dissolve all. Then, it cools and cobalt sulfate is deposited.

JP 2005-022887 A

  By the way, when recovering a desired metal from an actual scrap, it is particularly difficult to dissolve the entire amount of metal to be recovered, and a portion that cannot be completely dissolved is not recovered and is lost. In order to dissolve the total amount, using an excessive amount of acid or using an auxiliary agent such as hydrogen peroxide solution uses an expensive drug and is not an economical method. And yet, the goal of recovering all of the metal has not been reached.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a scrap melting method that enables the scrap to be effectively melted and a method for recovering metal from the scrap using this method.

  From the viewpoint of leaching scrap, it is important to dissolve the entire amount of metal to be recovered in the leachate in order to achieve the goal of total recovery. Therefore, as a result of intensive studies by the present inventors, it was found that the metal to be recovered dissolves very well by adding a transition metal compound made of a base metal rather than the metal to be recovered to the leachate. Completed.

That is, the present invention is as follows.
(1) A method of dissolving scrap of metal or metal oxide,
When performing acid leaching with a mineral acid, a compound of a transition metal that is less basic than all of the metal to be leached is added, and the metal to be leached is 90% by weight or more based on the amount contained in the scrap, A method for dissolving scrap, which dissolves in a leachate and makes the transition metal compound insoluble.
(2) The method according to (1), wherein the metal element of the transition metal compound is one of Fe, Ni, Co, and Mn.
(3) The method according to (1) or (2), wherein the scrap is a positive electrode material for a lithium ion secondary battery containing at least two types of Li, Ni, Co, and Mn.
(4) The method according to any one of (1) to (3), wherein the scrap is crushed.
(5) The scrap is dissolved in the leachate by the method according to any one of (1) to (4), then the transition metal compound is removed as an insoluble matter, and the metal is recovered from the liquor after the leaching. Recovering metal from scrap.

  According to the present invention, it is possible to effectively dissolve scrap, and it is possible to recover metal from scrap with a high recovery rate.

4 is a graph for comparing Example 1 and Comparative Example 1. FIG.

From one aspect, the present invention provides a scrap melting method.
That is, the present invention is a method of dissolving scrap of metal or metal oxide, and when performing acid leaching with a mineral acid, adding a transition metal compound composed of a base metal rather than a metal to be leached. This is a scrap melting method.

  The scrap that is the subject of the present invention is not particularly limited as long as it contains a metal or metal oxide, but an electronic material containing at least two types of Li, Ni, Co, and Mn, such as a semiconductor and an electronic component, a liquid crystal display, a tool, and the like. Examples thereof include scraps derived from coatings, glass coatings, optical disks, hard disks, solar cells, positive electrode materials for lithium ion secondary batteries, positive electrode materials and the like. In addition, this scrap is preferably crushed and powdered in advance in consideration of melting efficiency.

  Further, examples of the mineral acid used for acid leaching include sulfuric acid, hydrochloric acid, nitric acid, and sulfuric acid is preferable. Moreover, although it is the conditions of acid leaching, it is preferable that pH is 1 or less and temperature is 60 degreeC or more.

Further, during acid leaching, the transition metal compound is baser than the metal to be leached, but the metal element is appropriately selected according to the metal to be leached. Specifically, it is selected from any of Fe, Ni, Co, and Mn.
For example, when the metal to be leached is Li, Ni, or Co, Mn, which is lower than these, can be used as the metal element of the transition metal compound. Examples of the transition metal compound include sulfates, hydrochlorides, nitrates, acetates and oxides of the metal elements.

The transition metal compound is preferably added so as to be a transition metal corresponding to (target leaching rate−leaching rate due to acid alone). By using the transition metal compound at this ratio, the metal to be leached dissolves efficiently in the leaching solution. The dissolution ratio is preferably 90% by weight or more, more preferably 99% by weight or more, based on the weight contained in the positive electrode material for each metal.
During acid leaching, when the scrap is dissolved in the leachate, it is not clear why the metal to be leached dissolves efficiently by adding a base metal compound that is less leached than the metal to be leached. It is considered that a metal compound is dissolved in a compound composed of a target metal by replacing the target metal by an oxidation-reduction reaction to form the target metal in a salt form.
In this way, it is possible to efficiently dissolve a metal component that has been difficult to dissolve only by acid leaching using a large amount of acid. Thereby, it becomes possible to reduce the acid required for acid leaching, and the leaching time is also shortened.

  For example, taking a positive electrode material for a lithium ion secondary battery as an example, even if it is dissolved with a large amount of sulfuric acid of 2 equivalents of the total metal to be leached, it does not dissolve 100%, but a manganese compound such as manganese sulfate is added. By doing so, the metal to be leached nearly 100% can be dissolved in a short time only by using 1 equivalent of sulfuric acid.

From another aspect, the present invention provides a method for recovering metal from scrap.
That is, the present invention is a method for recovering metal from scrap, characterized in that after the scrap is dissolved in the leachate by the method described above, the transition metal compound is removed as an insoluble matter, and the metal is recovered from the liquor after leaching. It is.

Examples of the method for recovering the metal from the solution after leaching include a solvent extraction method and an electrolysis method, which can be separated as a metal or recovered as an alloy.
In the solvent extraction method, an organic phosphoric acid type acidic extraction agent such as di (2-ethylhexyl) phosphoric acid (D2EHPA) or 2-ethylhexyl 2-ethylhexylphosphonic acid (PC88A) used for usual metal extraction is used. The pH of the agent is appropriately adjusted, each metal ion is extracted into the organic phase, and separation and recovery can be performed by performing back extraction with an arbitrary acid.
In the electrolysis method, the solution after leaching is directly used as an electrolyte, and a cathode and an anode are installed, and electrolysis is performed at a constant current, so that it can be recovered by electrodeposition on the cathode or anode surface. .

Examples of the present invention will be described below, but the present invention is not limited to the examples.
Example 1
1 kg of ternary positive electrode scrap powder composed of oxides of Li, Ni, Co, and Mn was suspended in 10 L of an aqueous sulfuric acid solution containing 1 equivalent of sulfuric acid. Subsequently, 200 g of manganese sulfate was added to the suspension. As a result of leaching at 80 ° C. for 20 hours, Li was 100% by weight, Ni was 100% by weight, and Co was 99% by weight with respect to the content of each metal contained in the positive electrode material scrap. Mn became insoluble. Ni and Co, which are particularly valuable in this system, could be efficiently dissolved.
In addition, Ni and Co can be deposited and separated by electrolytically collecting this solution under normal conditions.

(Example 2)
1 kg of ternary positive electrode scrap powder composed of oxides of Li, Ni, Co, and Mn was suspended in 10 L of an aqueous sulfuric acid solution containing 1 equivalent of sulfuric acid. Subsequently, 500 g of manganese sulfate was added to the suspension. As a result of leaching at 80 ° C. for 5 hours, Li was 100% by weight, Ni was 100% by weight, and Co was 99% by weight with respect to the content of each metal contained in the positive electrode material scrap. Mn became insoluble. Ni and Co, which are particularly valuable in this system, could be efficiently dissolved. It should be noted that Ni and Co can be precipitated and separated by electrolytically collecting this solution.

(Comparative Example 1)
In Example 1, acid leaching was performed in the same manner except that manganese sulfate was not added. As a result of leaching for 20 hours at 80 ° C., 100% by weight of Li, 60% by weight of Ni and 60% by weight of Co were dissolved with respect to the content of each metal contained in the positive electrode material scrap. Mn became insoluble. Ni and Co, which are particularly valuable in this system, could not be completely dissolved.

(Comparative Example 2)
In Example 1, acid leaching was performed in the same manner except that manganese sulfate was not added. The acid concentration was 3 equivalents. As a result of leaching for 20 hours at 80 ° C., 100% by weight of Li, 80% by weight of Ni, and 80% by weight of Co were dissolved with respect to the content of each metal contained in the positive electrode material scrap. Mn became insoluble. Ni and Co, which are particularly valuable in this system, could not be completely dissolved.

Here, with respect to Example 1 and Comparative Example 1, the time change of the leaching rate of Li, Ni, and Co is shown in the graph of FIG.
According to FIG. 1, Li, Ni, Co, and Mn were added to the positive electrode material scrap containing Li, Ni, Co, and Mn (Example 1) and not (Comparative Example 1). A significant difference was observed. In particular, in Example 1, 80% or more was dissolved at a relatively fast stage, and nearly 100% of the metal was dissolved over time. On the other hand, in Comparative Example 1, it was predicted that the high proportion of dissolution realized in Example 1 would not occur even if time was spent.

Claims (5)

A method for melting metal or metal oxide scrap,
When performing acid leaching with a mineral acid, a compound of a transition metal that is less basic than all of the metal to be leached is added, and the metal to be leached is 90% by weight or more based on the amount contained in the scrap, A method for dissolving scrap, which dissolves in a leachate and makes the transition metal compound insoluble.   The method according to claim 1, wherein the metal element of the transition metal compound is one of Fe, Ni, Co, and Mn.   The method according to claim 1 or 2, wherein the scrap is a positive electrode material for a lithium ion secondary battery containing at least two types of Li, Ni, Co, and Mn.   The method according to claim 1, wherein the scrap is crushed.   After the scrap is dissolved in the leachate by the method according to any one of claims 1 to 4, the transition metal compound is removed as an insoluble matter, and the metal is recovered from the liquor after the leaching. For recovering metals from water.

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