Method for producing high-purity aluminum chloride from hydrochloric acid system corrosion aluminum foil waste acid solution

Abstract

The invention discloses a method for producing high-purity aluminum chloride by hydrochloric acid system corrosion aluminum foil waste acid liquid. The method comprises the following steps: filtering the waste acid liquid through a nanofiltration membrane to obtain first thin liquid and first thick liquid; the first thin liquid is recycled to a liquid preparation system of a workshop for repeated utilization, and the first concentrated liquid is collected for subsequent treatment; evaporating and concentrating the first concentrated solution through a graphite evaporator, and cooling to obtain aluminum trichloride hexahydrate crystals; separating the aluminum chloride hexahydrate crystal by a centrifugal machine to obtain solid aluminum chloride hexahydrate and mother liquor; and feeding the mother liquor into the graphite evaporator again, repeating the operations in the steps S2 and S3, and separating by a centrifugal machine to obtain solid aluminum chloride hexahydrate and distilled water. The method for producing high-purity aluminum chloride from the hydrochloric acid system corrosion aluminum foil waste acid solution has the advantages of low treatment cost and environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of waste liquid treatment technology, specifically relating to a method for producing high-purity aluminum chloride from waste acid liquid corroded by hydrochloric acid system for aluminum foil. Background Technology

[0002] Electrode foil etching utilizes electrochemical principles to etch and enlarge pores on the surface of electronic foil (aluminum foil) in sulfuric acid (hydrochloric acid). This process generates a large amount of acidic wastewater. Currently, the industry primarily uses alkali neutralization, which produces significant amounts of wastewater and solid waste, resulting in resource waste and secondary pollution. Secondly, some companies use resin ion exchange followed by alkali neutralization. This method only recovers a portion of the acid, still generating substantial amounts of solid waste and wastewater. Both methods suffer from high processing costs, hindering sustainable development for businesses. Summary of the Invention

[0003] The purpose of this invention is to provide a method for producing high-purity aluminum chloride from waste acid solution of aluminum foil corroded by hydrochloric acid system, in order to solve the above-mentioned problems existing in the prior art.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for producing high-purity aluminum chloride from waste acid solution obtained by corroding aluminum foil using a hydrochloric acid system includes the following steps: S1. The waste acid solution is filtered through a nanofiltration membrane to obtain a first dilute solution and a first concentrated solution; the first dilute solution is also a mixture of waste acid solutions.

[0005] S2. The first dilute solution is recycled to the workshop's liquid preparation system for repeated use, and the first concentrated solution is collected and further processed. S3. The first concentrated liquid is evaporated and concentrated in a graphite evaporator, and then cooled to obtain aluminum trichloride hexahydrate crystals. S4. Solid aluminum chloride hexahydrate and mother liquor were obtained by separating the crystals of aluminum chloride hexahydrate by centrifugation. S5. The mother liquor is reintroduced into the graphite evaporator, and steps S2 and S3 are repeated. After separation by centrifugation, solid aluminum trichloride hexahydrate and distilled water are obtained.

[0006] Furthermore, the first dilute solution accounts for 40%-50%, and the first concentrated solution accounts for 50%-60%.

[0007] Furthermore, the waste acid liquid includes free acid and aluminum ions, wherein the free acid content is 0.2N-6N and the aluminum ion content is 1.0N-1.8N.

[0008] Furthermore, the first concentrate includes free acid and aluminum ions.

[0009] Beneficial effects: This invention obtains hydrochloric acid and high-purity aluminum chloride through membrane filtration, multiple evaporation and concentration, and centrifugation, without generating waste liquid or solid waste. The entire process is green, environmentally friendly, and pollution-free, and has low processing costs, which is conducive to the sustainable development of enterprises. Detailed Implementation

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the description of the embodiments or the prior art. Example

[0011] This embodiment provides a method for producing high-purity aluminum chloride from waste acid solution that corrodes aluminum foil using a hydrochloric acid system, including the following steps: S1. The waste acid solution is filtered through a nanofiltration membrane to obtain a first dilute solution and a first concentrated solution; S2. The first dilute solution is recycled to the workshop's liquid preparation system for repeated use, and the first concentrated solution is collected and further processed. S3. The first concentrated liquid is evaporated and concentrated in a graphite evaporator, and then cooled to obtain aluminum trichloride hexahydrate crystals. S4. Solid aluminum chloride hexahydrate and mother liquor were obtained by separating the crystals of aluminum chloride hexahydrate by centrifugation. S5. The mother liquor is reintroduced into the graphite evaporator, and steps S2 and S3 are repeated. After separation by centrifuge, solid aluminum trichloride hexahydrate and distilled water are obtained. The distilled water can be reused in the production system.

[0012] In another embodiment of the present invention, the proportion of the first dilute liquid is 40%-50%, and the proportion of the first concentrated liquid is 50%-60%.

[0013] In another embodiment of the present invention, the waste acid liquid includes free acid and aluminum ions, with the free acid content being 0.2N-6N and the aluminum ion content being 1.0N-1.8N.

[0014] In another embodiment of the invention, the first concentrate comprises free acid and aluminum ions.

[0015] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing high-purity aluminum chloride from waste acid solution obtained by corroding aluminum foil using a hydrochloric acid system, characterized in that, Includes the following steps: S1. The waste acid solution is filtered through a nanofiltration membrane to obtain a first dilute solution and a first concentrated solution; S2. The first dilute solution is recycled to the workshop's liquid preparation system for repeated use, and the first concentrated solution is collected and further processed. S3. The first concentrated liquid is evaporated and concentrated in a graphite evaporator, and then cooled to obtain aluminum trichloride hexahydrate crystals. S4. Solid aluminum chloride hexahydrate and mother liquor were obtained by separating the crystals of aluminum chloride hexahydrate by centrifugation. S5. The mother liquor is reintroduced into the graphite evaporator, and steps S2 and S3 are repeated. After separation by centrifugation, solid aluminum trichloride hexahydrate and distilled water are obtained.

2. The method for producing high-purity aluminum chloride from waste acid solution of aluminum foil corroded by hydrochloric acid system according to claim 1, characterized in that, The first dilute solution accounts for 40%-50%, and the first concentrated solution accounts for 50%-60%.

3. The method for producing high-purity aluminum chloride from waste acid solution of aluminum foil corroded by hydrochloric acid system according to claim 1, characterized in that, The waste acid liquid includes free acid and aluminum ions, wherein the free acid content is 0.2N-6N and the aluminum ion content is 1.0N-1.8N.

4. The method for producing high-purity aluminum chloride from waste acid solution of aluminum foil corroded by hydrochloric acid system according to claim 1, characterized in that, The first concentrate contains free acid and aluminum ions.