RU2326186C2 - Recycling of lead plates with active mass of used accumulators - Google Patents

Abstract

FIELD: electro-chemistry.

SUBSTANCE: invention is related to the sphere of electro-chemical industries and is the method of recycling of lead plates with active mass of used accumulators. Method includes electrochemical dissolution of lead in electrolyte solution and it extraction from electrolyte. As electrolyte, solution of acetic acid is used with additives of nitric acid. Electrochemical dissolution is performed until dissolved lead concentration in electrolyte solution reaches 350-450 g/l, then the solution is separated from the insoluble residue, and the lead is extracted from the solution as end product - tribasic lead sulfate by settling with concentrated sulfuric acid. After depositing of lead, electrolyte is again sent for dissolution of lead plates.

EFFECT: provides ecological safety of process by means of using non-toxic components, high capacity and wastelessness of technology.

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Description

FIELD OF TECHNOLOGY

The invention relates to methods for electrochemical production, in particular to the processing of lead lead batteries that have fallen into disrepair.

BACKGROUND

There are a number of methods for processing lead-acid batteries with a view to their partial or final disposal:

1. A method involving the processing of pre-shredded scrap lead batteries by melting it in a crucible furnace in the presence of fluxes from alkali metal salts, recovery at 600-700 ° C and separate discharge of the product (Application for invention No. 95114825 07/27/1997).

The disadvantage of this method is the need for high temperatures and the use of flux.

2. A method of processing raw materials from used batteries, which consists in separation melting in a container with a perforated bottom and a water seal. By this method, antimony-free metallic lead is obtained (Patent of the Russian Federation No. 2146298, 03.10.2000).

The disadvantage of this method is the need to use non-standard equipment, as well as a large amount of non-utilizable residue.

3. A method of processing spent lead-acid batteries, which includes opening the batteries, separating the electrolyte, followed by melting to produce a crude lead-antimony alloy and refining it (Application for invention No. 98104676, 04.20.1999). The disadvantage of this method is the multi-stage, the use of high temperatures, gas emissions.

4. A method of processing lead-acid scrap based on the hydroseeding of crushed scrap with the subsequent separation of metal and oxide-sulfate fractions with further electric melting of these fractions (Patent of the Russian Federation No. 2164537, 03/27/2001). The disadvantages of this method are multi-stage and the formation of a large amount of liquid waste containing lead compounds and requiring additional purification.

5. The method of processing spent lead-acid batteries, which consists in the fact that the electrolyte is removed from the batteries and then subjected to metallurgical processing, including melting to obtain a lead-antimony alloy, followed by refining at a temperature not exceeding 1050 ° C (Patent of the Russian Federation 2125106, 20.01 .1999).

The disadvantages of this method are multi-stage, the use of high temperatures and sophisticated technological equipment.

6. A method of processing spent lead-acid batteries, which consists in the electrochemical processing of non-destroyed lead plates in a medium of sulfamic acid and the subsequent release of metallic lead at the cathode (Russian Federation Patent No. 2245393, January 27, 2005).

The closest in technical essence to the invention published by the author and adopted as a prototype is the patent of the Russian Federation No. 225393 01/27/2005 "Method of processing spent lead-acid batteries".

The disadvantages of this method are the use of a rather expensive sulfamic electrolyte, the duration of the process.

SUMMARY OF THE INVENTION

The goal that can be achieved by the invention is:

1. To environmental protection of the environment, which is due to the withdrawal of lead compounds from natural circulation.

2. Obtaining on their basis a valuable chemical product - tribasic sulfate of lead, which is a stabilizer of polyvinyl chloride (PVC).

The technical result is achieved by the fact that lead plates from spent batteries and containing an active sulfate-oxide mass used as an anode are placed in an electrolyzer containing an aqueous solution of acetic acid with the addition of nitric acid, where, by passing a direct current, electrochemical dissolution of metallic lead to a concentration of 350- 450 g / l in an electrolyte solution, followed by precipitation from lead electrolyte with sulfuric acid in the form of tribasic sulfate salt, its allocation. This salt can be used as a PVC stabilizer with the subsequent return of the electrolyte to the beginning of the process. A graphite electrode is used as a cathode. The anode space is separated from the cathode by a semipermeable membrane.

Another technical result of the invention is the ability to obtain soluble lead compounds, which are valuable starting materials for the paint industry, as well as the production of crystal glass enterprises.

In contrast to the known method of dissolving plates in an electrolyzer using sulfamic acid and releasing metallic lead at the cathode, in the present invention, lead is released into the solution in the form of lead acetate salt, followed by its transfer and separation from the solution in the form of tribasic lead sulfate and returning the electrolyte to the beginning of the process .

DETAILED DESCRIPTION OF THE INVENTION

Example

An electrolyte consisting of acetic acid with a concentration of 100-120 g / l with the addition of 5% nitric acid is poured into an electrolyzer equipped with a semipermeable membrane and having a graphite cathode. Lead plates with active mass are used as anodes. A constant voltage is applied to the electrodes. When direct current flows with a density of 35-45 mA / sq. Cm on the anode at room temperature, metal lead and active mass dissolve. As the lead plates and active mass dissolve and the lead acetate concentration in the solution reaches 350-450 g / l, the solution is separated by filtration from insoluble residues, dissolved lead is precipitated with a calculated amount of concentrated sulfuric acid with a density of 1.82-1.84 g / cc form of tribasic lead sulfate. The latter is separated by filtration, and the acetate solution is again sent to the electrochemical dissolution of the battery plates. In this way, almost complete utilization of lead is achieved.

In total, the reactions taking place in the electrolyzer:

On the anode:

RV-2e = RV ⁺²

In solution:

RVO + 2CH ₃ COOH = RV (CH ₃ COO) ₂

At the cathode:

2H ⁺ + 2e = H ₂

PB + 4HNO ₃ = PB (NO ₃ ) ₂ + 2NO ₂ + 2H ₂ O

The proposed method differs from the known prototype in that:

1. Instead of sulfamic acid, an inexpensive and non-toxic acetic acid is used as the electrolyte.

2. Lead from the solution is chemically separated in the form of tribasic lead sulfate and the return of the electrolyte to the beginning of the process.

The proceeding reaction is described by the formula

4PB (CH ₃ COO) ₂ + 3H ₂ O + H ₂ SO ₄ -3PBO · PB SO ₄ + 8CH ₃ COOH.

The objective of the invention is:

1. Environmental protection;

2. Recycling of used lead batteries;

3. Obtaining the most valuable component - tribasic lead sulfate, which is a stabilizer in the production of polyvinyl chloride (PVC).

The described method for processing used lead batteries to produce tribasic lead sulfate, a PVC stabilizer, has several advantages over existing methods for processing lead batteries:

1. Environmental cleanliness of the process - the absence of gas and dust emissions;

2. The room temperature of the process;

3. Use of non-toxic and inexpensive electrolyte components;

4. Electrolyte regeneration;

5. Non-waste technology.

In addition, this method allows the production of soluble lead salts, followed by their use in the paint and varnish and glass industries.

Claims (1)

A method of processing lead plates with an active mass of spent batteries, including electrochemical dissolution of lead in an electrolyte solution and its separation, characterized in that the solution of acetic acid with nitric acid additives is used as the electrolyte, the electrochemical dissolution is carried out to a concentration of dissolved lead in an electrolyte solution of 350-450 g / l, the solution is separated from insoluble residues and lead is isolated from it in the form of a commercial product - tribasic lead sulfate by precipitation ingly sulfuric acid.