Method for treating raffinate in copper hydrometallurgy process

Abstract

The invention discloses a method for treating raffinate in a copper hydrometallurgy process. According to the method, iron in the raffinate can be effectively recovered, and the generation amount of waste residues is greatly reduced. The treatment process comprises the following steps: reacting sodium phosphate with ferric iron to obtain an iron phosphate solid; carrying out solid-liquid separation and washing to obtain an iron phosphate byproduct; calcium hydroxide, sodium hydroxide, calcium oxide or sodium carbonate and the like are added into an aqueous solution to adjust the pH value to 6-9, so that residual ions such as iron, copper, zinc, aluminum and phosphate radicals (in a neutral or weakly alkaline environment, the phosphate radicals, the iron, the aluminum and the like are easier to form insoluble substances) form precipitates and are separated. The water quality after solid-liquid separation reaches the standard and is discharged, or is used for preparing a sodium phosphate solution. Iron phosphate is an important raw material for preparing lithium iron phosphate in a lithium battery, can also be used as a coloring agent, a metal surface treating agent and the like in glass and ceramic industries, and is wide in application.

Description

Technical Field

[0001] The invention relates to the technical field of copper hydrometallurgy, and in particular to a method for treating raffinate in a copper hydrometallurgy process. Background Art

[0002] During the copper hydrometallurgical process, a large amount of raffinate is produced during the copper extraction process; the raffinate contains a large amount of acid, iron, copper, aluminum and zinc. According to environmental protection requirements, the raffinate must be treated to meet the standards. The current treatment method is mainly based on lime neutralization. On the one hand, the acid can be neutralized, and on the other hand, the metal forms hydroxide precipitation and is removed; but this method will bring two problems: one is that valuable resources are not recycled; the other is that a large amount of waste slag will be generated. According to the estimate of processing 3,000 tons of raffinate per day, the iron loss in a year is as high as more than 13,000 tons; and the amount of waste slag generated in a year is as high as more than 100,000 tons (calculated at a moisture content of 50%). Therefore, it is necessary to seek a method for treating copper hydrometallurgical raffinate that can not only recycle valuable resources but also greatly reduce the amount of waste slag generated. Summary of the invention

[0003] In view of the above technical problems, the present invention provides a method for treating raffinate in a copper hydrometallurgical smelting process.

[0004] The technical solution of the present invention is as follows: A method for treating raffinate in a copper hydrometallurgical process comprises the following steps: S1. Prepare an aqueous sodium phosphate solution, then add it to the raffinate to react with ferric iron to generate an iron phosphate precipitate; S2. The reaction solution obtained in S1 is subjected to solid-liquid separation, and the separated solid is fully washed, purified and dried to obtain an iron phosphate byproduct; S3. Adjust the pH of the liquid phase obtained in S2 to 6-9, so that the remaining iron, copper, zinc, aluminum and phosphate (in a neutral or weakly alkaline environment, phosphate is more likely to form insoluble matter with iron, aluminum, etc.) are separated by precipitation. The water quality after solid-liquid separation meets the discharge standard or is used to prepare sodium phosphate solution.

[0005] Furthermore, in S1, the molar ratio of sodium phosphate to trivalent iron in the raffinate is 0.8-1.3:1, preferably 0.9-1.1:1, more preferably 1-1.1:1, further preferably 1-1.05:1, and most preferably 1:1. Sodium phosphate can be added in insufficient or excessive amounts, but by comparison, adding in a 1:1 manner has a better reaction effect.

[0006] Furthermore, in S1, the reaction pH is controlled at 3 to 5, preferably 4.

[0007] Further, in S3, the pH is adjusted by adding calcium hydroxide, sodium hydroxide, calcium oxide or sodium carbonate.

[0008] The iron phosphate obtained above is an important raw material for making lithium iron phosphate in lithium batteries, and can also be used as a colorant and metal surface treatment agent in the glass and ceramic industries.

[0009] The beneficial effects of the present invention are: The method of the present invention is used to treat the raffinate in the copper hydrometallurgy process, which can effectively recover the iron in the raffinate, and the treatment process is simple and easy; the produced product not only has good economic value, but also can greatly reduce the amount of waste residue generated. Compared with the lime method, the amount of waste residue is reduced by more than 80%. DETAILED DESCRIPTION

[0010] The present invention is further described in detail below with reference to specific embodiments, but the present invention is not limited thereto. Example 1

[0011] A method for treating raffinate in a copper hydrometallurgical process comprises the following steps: S1. Sodium phosphate is prepared into a 10% aqueous solution by mass, and then added to the raffinate under stirring to react with trivalent iron, and the pH is controlled to about 4 to generate iron phosphate precipitate; S2. The aqueous solution obtained in S1 is subjected to solid-liquid separation, and after solid-liquid separation, it is fully washed with water, and dried to obtain a white or off-white iron phosphate byproduct; S3. The liquid phase obtained in S2 is adjusted to a pH of about 8 by adding calcium hydroxide. The residual aluminum, iron, zinc and phosphate (in a neutral or weakly alkaline environment, phosphate is more likely to form insoluble matter with iron, aluminum, etc.) in the solution are precipitated and removed, and the clarified water meets the discharge standards. Example 2

[0012] A method for treating raffinate in a copper hydrometallurgical process comprises the following steps: S1. Sodium phosphate is prepared into a 12% aqueous solution by mass, and then added to the raffinate under stirring to react with trivalent iron, and the pH is controlled to about 4.5 to generate iron phosphate precipitate; S2..the aqueous solution obtained in S1 is subjected to solid-liquid separation. After solid-liquid separation, the solid is fully washed with clean water, and a white or off-white iron phosphate byproduct is obtained after drying; S3. The liquid phase obtained in S2 is adjusted to a pH of about 8 by adding sodium hydroxide. The residual aluminum, iron, zinc and phosphate (in a neutral or weakly alkaline environment, phosphate is more likely to form insoluble matter with iron, aluminum, etc.) in the solution are precipitated and removed, and the clarified water meets the discharge standards. Example 3

[0013] A method for treating raffinate in a copper hydrometallurgical process comprises the following steps: S1. Sodium phosphate is prepared into a 14% aqueous solution by mass, and then added to the raffinate under stirring to react with trivalent iron, and the pH is controlled to about 5 to generate iron phosphate precipitate; S2. The aqueous solution obtained in S1 is subjected to solid-liquid separation. After solid-liquid separation, the solid is fully washed with water and dried to obtain a white or off-white iron phosphate byproduct; S3. The liquid phase obtained in S2 is adjusted to a pH of about 8 by adding sodium carbonate. The residual aluminum, iron, zinc and phosphate (in a neutral or weakly alkaline environment, phosphate is more likely to form insoluble matter with iron, aluminum, etc.) in the solution are precipitated and removed, and the clarified water meets the discharge standards.

Claims

1. A method for treating raffinate in a copper hydrometallurgical process, characterized in that: The steps include: S1. Prepare an aqueous sodium phosphate solution, then add it to the raffinate to react with ferric iron to generate an iron phosphate precipitate; S2. The reaction solution obtained in S1 is subjected to solid-liquid separation, and the separated solid is washed, purified and dried to obtain an iron phosphate product; S3. The pH of the liquid phase obtained in S2 is adjusted to 6-9, so that the remaining iron, copper, zinc, aluminum and phosphate ions are precipitated and separated.

2. The method for treating raffinate in a copper hydrometallurgy process according to claim 1, characterized in that: In S1, the molar ratio of sodium phosphate to ferric iron in the raffinate is 0.8-1.3:

1.

3. The method for treating raffinate in a copper hydrometallurgy process according to claim 1, characterized in that: In S1, the molar ratio of sodium phosphate to ferric iron in the raffinate is 0.9-1.1:

1.

4. The method for treating raffinate in a copper hydrometallurgy process according to claim 1, characterized in that: In S1, the molar ratio of sodium phosphate to the trivalent iron in the raffinate is 1.0-1.1:

1.

5. The method for treating raffinate in a copper hydrometallurgy process according to claim 1, characterized in that: In S1, the molar ratio of sodium phosphate to trivalent iron in the liquid phase is 1-1.05:

1.

6. The method for treating raffinate in a copper hydrometallurgy process according to claim 1, characterized in that: In S1, the molar ratio of sodium phosphate to ferric iron in the liquid phase is 1:

1.

7. The method for treating raffinate in a copper hydrometallurgy process according to claim 1, characterized in that In S1, the reaction pH is controlled at 3-5.

8. The method for treating raffinate in a copper hydrometallurgy process according to claim 1, characterized in that: In S3, the pH is adjusted by adding sodium hydroxide, calcium hydroxide, calcium oxide or sodium carbonate.

9. The method for treating raffinate in a copper hydrometallurgy process according to claim 1, characterized in that: In S3, the water quality after solid-liquid separation meets the discharge standards or is used to prepare sodium phosphate solution.