JP2002226923A - Method for recovering valuable metal from nickel- hydrogen secondary battery scrap - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for economically recovering valuable metals such as nickel, cobalt or rare earth elements contained in nickel-hydrogen secondary battery scrap. SOLUTION: Recovered active material obtained by crushing a used nickel- hydrogen secondary battery and performing physical separation such as sieving is dissolved while blowing gaseous chlorine in hydrochloric acid. Nickel, cobalt and rare earth elements are recovered into a solution, and manganese is selectively precipitated, so that nickel, cobalt and rare earth elements, and manganese are separately recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering valuable metals such as nickel contained in nickel-metal hydride secondary battery scrap.

[0002]

2. Description of the Related Art Nickel-metal hydride secondary batteries have recently been used as secondary batteries in place of nickel-cadmium batteries for batteries of electric vehicles, mobile phones, and the like, and demand has been rapidly increasing. This nickel-metal hydride secondary battery has a positive electrode filled with nickel hydroxide as an active material on a punched plate plated with nickel on porous nickel or iron, a negative electrode filled with a hydrogen storage alloy, and a separator such as polypropylene. These are stored together with the electrolyte in a steel or polypropylene container.

[0003] Nickel-metal hydride secondary batteries have better characteristics than nickel-cadmium batteries and do not use harmful cadmium. Therefore, even if they are disposed of, they do not cause serious pollution. Since alloys are a valuable resource, recycling these valuable metals is extremely important.

However, in the method of recovering valuable metals from used nickel-metal hydride secondary batteries, batteries have been downsized as electric appliances have become more compact. It is difficult to recover to purity. In addition, particularly when used in a battery for an automobile, it is difficult to be easily disassembled because it has a structure that is hard to be broken by a car collision or the like. Therefore, in order to recover valuable metals from used nickel-metal hydride batteries, it is necessary to crush all batteries and separate crushed materials, which is an economical recovery method.

[0005] As a method of recovering valuable metals from the crushed nickel-hydrogen secondary batteries, particularly for the purpose of recovering nickel in particular, first of all, various types of physical separation, such as magnetic separation and specific gravity separation, are used to separate the containers and plates. It is separated and collected into most of the component iron and an active material containing nickel or the like for the purpose of recovery. The separated and recovered active material is dissolved in a mineral acid, and the resulting solution is subjected to chemical treatment to separate and recover a desired valuable metal such as nickel.
This chemical treatment is performed to separate rare earths and other elements contained in the solution in order to recover nickel and the like with as high a purity as possible.

In the above method, the active material separated and recovered from iron and the like is a mixture of a positive electrode material and a negative electrode material. Processing is performed. When dissolving with these mineral acids, it is difficult to dissolve only the target metal, and other elements such as iron and manganese are also dissolved at the same time as valuable metals such as nickel for the purpose of recovery. Therefore, it is necessary to separate from the target metal.

However, for the purpose of recovering nickel, for example, since it is difficult to remove elements other than nickel at the same time, there are various methods such as removal of iron by neutralization, removal of rare earth by carbonation, and removal of manganese by oxidative precipitation. A separation step by chemical treatment is required for each element. Further, there is a problem that the cost of the drug is increased and a solid-liquid separation step of each precipitate is required, which complicates the step.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for recovering valuable metals from used nickel-metal hydride secondary battery scraps, and more particularly to provide a recovery method in which the number of chemical treatment steps is reduced.

[0009]

According to the present invention, there is provided a nickel-hydrogen secondary battery obtained by subjecting a used nickel-metal hydride secondary battery to physical separation such as crushing scrap and sieving. In this method, an active material containing a rare earth element or the like is dissolved by injecting chlorine gas with hydrochloric acid, nickel, cobalt, the rare earth element or the like is recovered in a solution, and manganese is selectively precipitated by separation. According to this method, it is possible to save labor in the chemical treatment step for removing manganese in the conventional method.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for recovering valuable metals from nickel-metal hydride secondary battery scrap according to the present invention, first, used nickel-metal hydride secondary battery scrap is crushed to obtain crushed material. Thereafter, the crushed material is stirred in water to disperse the positive electrode, the negative electrode current collector, the plastics, and the active material so that the active material can be easily collected in the next sieving step.

At this time, plastics such as a separator are liable to float, and are used to separate the plastics. The crushed material dispersed in water is sieved, the outer container mainly composed of iron, the positive and negative electrode current collectors are separated on the sieve, and the active material containing valuable metals to be collected is separated under the sieve.
The resulting sieve is a mixture of nickel and cobalt hydroxides as positive electrode materials and a hydrogen storage alloy containing manganese and rare earth elements as negative electrode materials.

In particular, in the method of the present invention, nickel in the hydrogen storage alloy is also recovered in order to increase the recovery rate of nickel, which is the main purpose. For this reason, the entire amount under the sieve was dissolved with hydrochloric acid. The pH at the time of dissolution must be 3 or less. When the pH is higher than the above, the dissolution rate of the target valuable metal is reduced, and the recovery rate is reduced.

When hydrochloric acid is used to dissolve under a sieve containing an active material as a main component, it can be dissolved almost completely, and the dissolution rate of nickel is 9%.
A liquid as high as about 7% is obtained. At this time, by blowing chlorine gas, manganese is oxidized and selectively precipitated. By utilizing this, nickel, cobalt, rare earth elements and the like can be recovered in a solution, and only manganese can be selectively precipitated to be separated and recovered.

[0014]

(Example 1) A cylindrical nickel-metal hydride secondary battery scrap having a diameter of 30 mm and a height of 50 mm was crushed by using a good cutter manufactured by Ujiie Seisakusho Co., Ltd., which is a kind of column crusher, and was crushed by 5 mm. While crushing the crushed material using a sieve, the crushed material was repeatedly crushed on the sieve until there was no electrode visually.

An iron-nickel-plated punched plate was used for the positive and negative electrode current collectors, and a polypropylene nonwoven fabric was used for the separator separating the positive electrode and the negative electrode. After the obtained crushed material was stirred in water for 1 hour, the floating separator was scooped with a mesh having a mesh of 0.5 mm.

Thereafter, the residue was manually subjected to wet sieving using a sieve having a diameter of 300 mm and a sieve of 0.5 mm to obtain an active material under the sieve. Using 25 g of the obtained active material, chlorine gas was blown into 500 ml of water, and the dissolution temperature was 80:
C., dissolution time: 2 hours, dissolution pH was controlled by adding hydrochloric acid to be 1, and the slurry was dissolved at a slurry concentration of 50 g / l. The concentration of hydrochloric acid used was 6 mol / liter,
The blown chlorine gas was 0.5 liter / min.

(Comparative Example 1) As Comparative Example 1, under the same conditions as in Example 1, air was blown instead of chlorine gas to dissolve. The concentration of hydrochloric acid used was 6 mol / l, and the air blown was 0.5 l / min.

Comparative Example 2 As Comparative Example 2, sulfuric acid was added under the same conditions as in Example 1 so as to obtain a dissolution pH of 1, and the mixture was dissolved by blowing air. The concentration of sulfuric acid used was 47%, and the air blown was 0.5 liter / min.

Table 1 shows the dissolution rate of each element in Examples and Comparative Examples.
Shown in As shown in Table 1, when the active material was dissolved by blowing hydrochloric acid + chlorine gas, the dissolution rate of manganese was 2.8%, and a liquid from which manganese was separated was obtained. When the active material was dissolved by blowing hydrochloric acid and air, and when dissolving by sulfuric acid and air, manganese was also dissolved together with nickel, cobalt, and rare earth, and manganese could not be separated.

Therefore, it can be seen that by dissolving the active material by blowing hydrochloric acid + chlorine gas, nickel, cobalt, and rare earth elements can be recovered in the solution, and only manganese can be selectively precipitated and separated and recovered.

[0021]

According to the method for recovering valuable metals from used nickel-metal hydride secondary battery scraps according to the present invention, manganese can be precipitated and separated from nickel, cobalt and rare earth elements at the time of leaching mineral acids from active materials. In addition, valuable metals can be economically recovered from nickel-metal hydride secondary battery scrap by saving labor in the manganese separation step.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22B 59/00 C22B 3/00 Q H01M 10/54 23/04 F term (Reference) 4K001 AA07 AA16 AA19 AA39 BA22 CA01 CA02 CA03 CA04 DB04 DB23 5H031 AA02 BB02 BB03 BB09 EE01 EE03 RR02

Claims (1)

[Claims] 1. A nickel hydrogen rechargeable battery scrap is crushed, and the recovered active material obtained by physical separation such as sieving, magnetic separation, and specific gravity separation is dissolved with hydrochloric acid while blowing chlorine gas, and nickel, cobalt, rare earth elements are dissolved. A method for recovering valuable metals from nickel-metal hydride secondary battery scrap, comprising recovering elements in a solution, selectively precipitating manganese, and recovering the separated manganese.