RU2157343C1 - Method of production of lead hydroxide (ii) - Google Patents

Abstract

FIELD: electrochemical processes; methods of production of lead hydroxide (II) from lead-containing wastes. SUBSTANCE: method consists in electrochemical anode dissolving; lead-containing compounds are dissolved after cathode treatment at current density of 20 mA/sq.cm in potassium nitrate solution at anode density of 0.25 A/sq.cm. EFFECT: possibility of recovery of lead containing wastes without addition of chemical reagents; waste-free technology of more pure lead hydroxide (II). 4 ex

Description

 The invention relates to the field of electrochemical production, and more specifically to methods for producing lead (II) hydroxide from lead-containing waste.

 The invention can be used to obtain lead white, lead sulfate and other lead compounds.

 A known method of electrochemical processing of lead-containing oxidized products, including leaching of lead with an alkaline solution with simultaneous electrochemical separation of lead in the form of a cathode sponge [1] / Auth. St. N 1308609, class C 09 C 1/04, C 01 C 9/02 dated 03/25/85 /.

 The disadvantage of this method is the use of reagents for leaching of lead.

 The closest way to the same purpose for the combination of features is a method for producing lead (II) hydroxide [2] / Pat. N 2006525, cl. 5 C 25 B 1/00, C 01 C 21/16 from 06/27/91 /, including the preparation of galena in a chloride-containing solution and its subsequent supply to electrochemical dissolution.

 For reasons that impede the achievement of the specified result when using the known method adopted as a prototype, the lead sulfide is precipitated in the known method using a valuable chemical reagent. Another disadvantage of this method is that during the electrochemical oxidation of lead sulfide, sulfur dioxide is formed on the anode, which requires additional costs to capture and process it.

 The task of the invention is environmental cleanliness and environmental protection.

 The technical result is an increase in the efficiency of the method due to the disposal of lead-containing waste without the addition of chemicals and waste-free technology for the production of more pure lead (II) hydroxide.

The specified technical result in the implementation of the invention is achieved by the fact that the electrochemical anodic dissolution is carried out after the cathodic treatment of lead-containing compounds at a current density of 20 mA / cm ² in a solution of potassium nitrate at an anodic current density of 0.25 A / cm ² .

 The analysis of the prior art by the applicant, including a search by patent and scientific and technical sources of information, and the identification of sources containing information about analogues of the claimed invention, allowed to establish that the applicant did not find a source characterized by features identical to those of the claimed invention.

The essence of the invention lies in the fact that during the electrochemical treatment of lead-containing compounds, electrolysis is carried out in an aqueous solution at constant current, using battery plates containing PbO ₂ , PbO, PbSO ₄ , and metallic lead as an electrode.

 Electrolysis is carried out as follows.

The fixed lead plates are lowered into a glass beaker, a solution of potassium nitrate is poured. The electrode plates are connected in series as a cathode for the reduction of lead oxides at a current density of 20 mA / cm ² and then as an anode for their dissolution with the formation of lead (II) hydroxide at a current density of 0.25 A / cm ² . At a cathodic current density above 20 mA / cm ² , hydrogen evolution begins at the cathode. The choice of anode current density is related to the performance of the process. At a current density above 0.25 A / cm ^{2 the} solution heats up, the yield of the substance decreases; at a current density below 0.25 A / cm ^{2 the} productivity of the cell is low.

Example 1. The electrolysis was carried out in a glass beaker with a capacity of 500 ml. The cathode is a lead plate of the spent battery, cathode density of 20 mA / cm ² . The anode is a cathodically restored lead plate, the anode density of 0.1 A / cm ² . The electrolyte is a 0.1 M solution of potassium nitrate. Temperature 20 ^o C. The yield of the substance is 90%.

Example 2. Electrolysis is carried out according to claim 1: anodic current density of 0.25 A / cm ² . The yield of the substance is 96-98%.

Example 3. The electrolysis is carried out according to p. 1: anode current density of 0.3 A / cm ² . The yield of the substance is 94%.

Example 4. Electrolysis is carried out according to claim 1: anodic current density of 0.25 A / cm ² . The electrolyte is a 0.2 M solution of potassium nitrate. Temperature 20 ^o C. The yield of the substance is 97%.

The proposed method for the production of lead (II) hydroxide allows:
1. To carry out the process without the addition of chemicals and, therefore, there is no need for additional costs.

 2. An electric current is used as a reducer of lead oxides, not chemical reagents.

 3. As a result of electrolysis, lead (II) hydroxide is formed, which is the raw material for producing lead compounds.

 4. Further processing of lead (II) hydroxide with carbon dioxide makes it possible to obtain basic lead carbonate (lead white), which is used in the paint and varnish industry.

 Thus, the above information indicates that the proposed method during its implementation is intended for use in industry, namely, in paint and varnish, chemical, etc.

 Bibliographic data.

 1. Auth. St. N 1308609, class C 09 C 1/04, C 01 C 9/02 of 03/25/85.

 2. Pat. N2006525, cl. 5 C 25 B 1/00, C 01 C 21/16 dated 06/27/91.

Claims (1)

A method of producing lead (II) hydroxide by electrochemical anodic dissolution, characterized in that the dissolution of lead-containing compounds is carried out after cathodic treatment at a current density of 20 mA / cm ² in a solution of potassium nitrate at an anodic density of 0.25 mA / cm ² .