Wastewater treatment method for extracting iron and copper from copper hydrometallurgy raffinate

Abstract

The invention discloses a wastewater treatment method for extracting iron and copper from copper hydrometallurgy raffinate. The method comprises the following steps: adding an alkaline solution into a copper hydrometallurgy raffinate to enable ferric iron to form ferric hydroxide precipitate, carrying out solid-liquid separation and washing, and calcining the precipitate to obtain an iron oxide red product; iron powder is added into the liquid, copper ions are reduced into metal copper, and solid-liquid separation is carried out on the metal copper and the remaining iron powder through precipitation; solid circulation is used for reducing iron powder, then copper powder purification is conducted, and pure copper powder is obtained; and adding an alkaline substance into the liquid to adjust the pH to be neutral, carrying out solid-liquid separation, discharging clear water reaching the standard, and carrying out sludge dewatering treatment. After the iron in the wastewater is utilized by the method, the alkali required by the neutralization reaction is obviously reduced, and the alkali consumption of lime is reduced by more than 2 / 3; the waste residue amount is reduced by about 70%, and the water quality is stable and reaches the standard for discharge. Iron and copper in the raffinate are recycled, iron oxide red and copper powder products are produced, remarkable economic benefits are brought, and unification of environmental benefits and economic benefits is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of copper hydrometallurgy, and in particular to a wastewater treatment method for extracting iron and copper from hydrometallurgy copper raffinate. Background Art

[0002] During the process of wet copper smelting, a large amount of raffinate is produced; the raffinate contains a large amount of acid, iron, aluminum, and different contents of copper, zinc, calcium and magnesium; in order to meet environmental protection requirements, the raffinate must be effectively treated. The current treatment method is lime neutralization. Lime neutralization is a traditional wastewater treatment technology that neutralizes acids and other pollutants such as aluminum, zinc, iron and copper by adding lime (calcium hydroxide) to wastewater; the advantage of this method is that it is simple to operate and can achieve standard discharge by controlling pH; but its more prominent problems are: the resources in the wastewater cannot be recycled, the lime consumption is high, and the slag production is large. One ton of raffinate requires dozens of kilograms of lime to neutralize, and hundreds of kilograms of wet slag will be produced; not only is the treatment cost high, but the huge amount of waste slag is also the most troublesome problem for mining companies; although scientific and technological personnel have conducted years of research, they have not yet broken through the application bottleneck; currently, copper mines still generally use lime neutralization to treat wet copper smelting raffinate.

[0003] To reduce the amount of waste slag, it is necessary to utilize certain components in the raffinate. In the neutralization reaction, trivalent iron is an important factor in consuming alkali; therefore, it is possible to consider separating iron from the wastewater in the form of precipitation, which can not only recycle the iron element, but also reduce the consumption of alkali and the amount of slag produced, achieving the dual benefits of comprehensive utilization and emission reduction. The separated iron can be used to produce red iron oxide. Red iron oxide is an important chemical raw material. Due to its excellent light resistance, high temperature resistance, strong hiding power and tinting power, it is widely used in many industries such as construction, coatings, plastics, rubber, etc., and the demand is large. Recycling copper in the raffinate can also produce obvious economic benefits.

[0004] Therefore, by recovering the iron and copper in the raffinate, red iron oxide and copper powder products are produced, thereby obtaining significant economic benefits and achieving the unity of environmental and economic benefits. Summary of the invention

[0005] In order to reduce the amount of waste slag generated in the hydrometallurgical copper smelting process and improve the recovery value of the extract, the present invention provides a wastewater treatment method for extracting iron and copper from the hydrometallurgical copper smelting raffinate, by recovering the iron and copper in the raffinate, producing iron oxide red and copper powder products, thereby achieving the unity of environmental benefits and economic benefits.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate, comprising the following steps:

[0008] S1. Adding an alkaline solution to the raffinate of hydrometallurgical copper smelting to control the pH to 3 to 3.2, so that the trivalent iron forms ferric hydroxide precipitation;

[0009] S2. The iron hydroxide precipitate obtained in step S1 is subjected to solid-liquid separation and the precipitate is washed;

[0010] S3. The iron hydroxide precipitate obtained in step S2 is calcined to obtain a red iron oxide product;

[0011] S4. Add iron powder to the liquid obtained by solid-liquid separation in step S2, so that the copper ions are reduced to metallic copper, and the copper ions are separated from the remaining iron powder by precipitation; the solid obtained by solid-liquid separation is reused in step S4 several times (for the purpose of accumulating a large amount of metallic copper), and then the copper powder is purified to obtain pure copper powder;

[0012] S5. Add alkaline substances to the liquid obtained by solid-liquid separation in step S4 to adjust the pH to neutral. After solid-liquid separation, the clean water meets the discharge standards and the sludge is dehydrated for disposal.

[0013] Furthermore, in step S1, the alkaline solution is a mixture of one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide and potassium hydroxide.

[0014] Furthermore, in step S1, the pH is preferably 3.

[0015] Furthermore, in step S2, the iron hydroxide precipitate is washed with clean water.

[0016] Furthermore, in step S3, the calcination temperature is 500 to 800° C., preferably 600 to 800° C.; the calcination time is 0.5 to 6 hours, preferably 1 to 3 hours.

[0017] Furthermore, the copper powder is purified as follows: the solid obtained by S4 solid separation is used to separate the iron powder by magnetic separation, dilute sulfuric acid or dilute hydrochloric acid is added to the separated initial copper powder to further remove the residual iron powder, and pure copper powder is obtained after separation, washing and drying.

[0018] Furthermore, in step S5, the alkaline substance is selected from lime (ordinary lime or ultrafine lime), sodium carbonate, nano alkali or composite alkali, and the ultrafine lime is lime powder with a mesh size of 200 or more.

[0019] Furthermore, the mass fraction of the dilute sulfuric acid or dilute hydrochloric acid is 5% to 40%.

[0020] In the above method, in order to improve the purity of red iron oxide, according to the difference in solubility product of hydroxides such as iron, aluminum, copper, and zinc, when adding alkaline solutions such as sodium carbonate aqueous solution or sodium hydroxide aqueous solution, the pH value of the solution is strictly controlled to precipitate iron while other metals do not precipitate; after solid-liquid separation and washing, relatively pure iron hydroxide is obtained; after calcination, the ideal red iron oxide product is obtained. A certain amount of reduced iron powder is added to the aqueous solution after solid-liquid separation. After sufficient stirring and reaction, the metallic copper powder and the unreacted iron powder are separated from the liquid phase by natural sedimentation, and the mixed powder is recycled for reducing iron powder. When the copper powder accumulates to a certain amount, the iron powder is separated by magnetic separation, and the primary copper powder is treated with dilute acid to obtain a pure copper powder product. After neutralization treatment with alkaline substances such as ultrafine lime in the aqueous solution, it meets the discharge standards, and the filter residue is safely disposed of.

[0021] The beneficial effects of the present invention are:

[0022] After the iron in the wastewater is utilized by the method of the present invention, the alkali required for the neutralization reaction is significantly reduced, and the amount of lime used is reduced by more than two-thirds; the amount of waste residue is reduced by about 70%, and the water quality is stable and meets the discharge standards. More importantly, by recovering the iron and copper in the raffinate, the iron oxide red and copper powder products produced are high in purity and good in quality. The purity of the iron oxide red reaches more than 98%, and the purity of the copper powder reaches more than 99%, which brings significant economic benefits and realizes the unity of environmental benefits and economic benefits. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to specific embodiments, but the present invention is not limited thereto.

[0024] Example 1

[0025] A method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate, comprising the following steps:

[0026] S1. adding sodium hydroxide solution to the raffinate of hydrometallurgical copper smelting to control the pH to 3 so that ferric iron forms ferric hydroxide precipitate;

[0027] S2. The iron hydroxide precipitate obtained in step S1 is subjected to solid-liquid separation and washed with water;

[0028] S3. The iron hydroxide precipitate obtained in step S2 is calcined at 600°C for 1 hour to obtain a red iron oxide product;

[0029] S4. Add iron powder to the liquid obtained by solid-liquid separation in step S3, so that the copper ions are reduced to metallic copper, and the copper ions are separated from the remaining iron powder by precipitation; the solid obtained by solid-liquid separation is reused in step S4 several times, and then the separated solid is separated from the iron powder by magnetic separation, and 10% by mass of dilute sulfuric acid is added to the separated primary copper powder to further remove the residual iron powder, and pure copper powder is obtained after separation, washing and drying;

[0030] S5. Add ultrafine lime to the liquid obtained by solid-liquid separation in step S4 to adjust the pH to neutral. After solid-liquid separation, the clean water meets the discharge standards and the sludge is dehydrated for disposal.

[0031] Example 2

[0032] A method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate, comprising the following steps:

[0033] S1. Adding sodium carbonate solution to the raffinate of hydrometallurgical copper smelting to control the pH to 3, so that trivalent iron forms ferric hydroxide precipitate;

[0034] S2. The iron hydroxide precipitate obtained in step S1 is subjected to solid-liquid separation and washed with water;

[0035] S3. The iron hydroxide precipitate obtained in step S2 is calcined at 500°C for 0.5 hours to obtain a red iron oxide product;

[0036] S4. Add iron powder to the liquid obtained by solid-liquid separation in step S3, so that the copper ions are reduced to metallic copper, and the copper ions are separated from the remaining iron powder by precipitation; the solid obtained by solid-liquid separation is reused in step S4 several times, and then the separated solid is separated from the iron powder by magnetic separation, and 40% by mass of dilute sulfuric acid is added to the separated primary copper powder to further remove the residual iron powder, and the pure copper powder is obtained after separation, washing and drying;

[0037] S5. Add common lime to the liquid obtained by solid-liquid separation in step S4 to adjust the pH to neutral. After solid-liquid separation, the clean water meets the discharge standards and the sludge is dehydrated for disposal.

[0038] Example 3

[0039] A method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate, comprising the following steps:

[0040] S1. Adding sodium bicarbonate solution to the hydrometallurgical copper raffinate to control the pH to 3.2, so that the trivalent iron forms ferric hydroxide precipitation;

[0041] S2. The iron hydroxide precipitate obtained in step S1 is subjected to solid-liquid separation and washed with water;

[0042] S3. The iron hydroxide precipitate obtained in step S2 is calcined at 650°C for 3 hours to obtain a red iron oxide product;

[0043] S4. Add iron powder to the liquid obtained by solid-liquid separation in step S2, so that the copper ions are reduced to metallic copper, and the copper ions are separated from the remaining iron powder by precipitation; the solid obtained by solid-liquid separation is reused in step S4 several times, and then the separated solid is separated from the iron powder by magnetic separation, and 15% by mass of dilute sulfuric acid is added to the separated primary copper powder to further remove the residual iron powder, and pure copper powder is obtained after separation, washing and drying;

[0044] S5. Sodium carbonate is added to the liquid obtained by solid-liquid separation in step S4 to adjust the pH to neutral. After solid-liquid separation, the clean water meets the discharge standards and the sludge is dehydrated for disposal.

[0045] Example 4

[0046] A method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate, comprising the following steps:

[0047] S1. A mixed alkaline solution of sodium hydroxide and sodium carbonate is added to the hydrometallurgical copper raffinate to control the pH to 3.2 so that trivalent iron forms ferric hydroxide precipitate;

[0048] S2. The iron hydroxide precipitate obtained in step S1 is subjected to solid-liquid separation and washed with water;

[0049] S3. The iron hydroxide precipitate obtained in step S2 was calcined at 750°C for 4.5 hours to obtain a red iron oxide product;

[0050] S4. Add iron powder to the liquid obtained by solid-liquid separation in step S2, so that the copper ions are reduced to metallic copper, and the copper ions are separated from the remaining iron powder by precipitation; the solid obtained by solid-liquid separation is reused in step S4 several times, and then the separated solid is separated from the iron powder by magnetic separation, and a mass fraction of 5% dilute hydrochloric acid is added to the separated initial copper powder to further remove the residual iron powder, and the pure copper powder is obtained after separation, washing and drying;

[0051] S5. Add nano alkali to the liquid obtained by solid-liquid separation in step S4 to adjust the pH to neutral. After solid-liquid separation, the clean water meets the discharge standards and the sludge is dehydrated for disposal.

Claims

1. A wastewater treatment method for extracting iron and copper from hydrometallurgical copper raffinate, characterized in that: The following steps are involved: S1. Adding an alkaline solution to the raffinate of hydrometallurgical copper smelting to control the pH to 3-3.2, so that the trivalent iron forms ferric hydroxide precipitation; S2. The iron hydroxide precipitate obtained in step S1 is subjected to solid-liquid separation and washing; S3. calcining the iron hydroxide precipitate obtained in step S2 to obtain a red iron oxide product; S4. Add iron powder to the liquid obtained by solid-liquid separation in step S2, so that the copper ions are reduced to metallic copper, and the solid-liquid separation is performed with the remaining iron powder by precipitation; the solid obtained by solid-liquid separation is reused in step S4 several times, and then the copper powder is purified to obtain pure copper powder; S5. Add alkaline substances to the liquid obtained by solid-liquid separation in step S4 to adjust the pH to neutral. After solid-liquid separation, the clean water meets the discharge standards and the sludge is dehydrated for disposal.

2. The method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate according to claim 1, characterized in that: In step S1, the alkaline solution is one or a mixture of sodium carbonate, sodium bicarbonate, sodium hydroxide, and potassium hydroxide.

3. The method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate according to claim 1, characterized in that: In step S1, the pH is 3.

4. The method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate according to claim 1, characterized in that: In step S2, the iron hydroxide precipitate is washed with clean water.

5. The method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate according to claim 1, characterized in that: In step S3, the calcination temperature is 500-800° C. and the calcination time is 0.5-6 hours.

6. The method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate according to claim 1, characterized in that: In step S3, the calcination temperature is 600-800° C. and the calcination time is 1-3 hours.

7. The method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate according to claim 1, characterized in that: The copper powder purification is specifically as follows: the solid obtained by S4 solid separation is used to separate the iron powder by magnetic separation, dilute sulfuric acid or dilute hydrochloric acid is added to the separated initial copper powder to further remove the residual iron powder, and pure copper powder is obtained after separation, washing and drying.

8. The method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate according to claim 1, characterized in that: In step S5, the alkaline substance is selected from lime, sodium carbonate, nano alkali or composite alkali.

9. The method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate according to claim 8, characterized in that: The lime is ordinary lime or superfine lime, and the superfine lime is lime powder with a mesh size of 200 or more.

10. The method for treating wastewater for extracting iron and copper from hydrometallurgical copper raffinate according to claim 7, characterized in that: The mass fraction of dilute sulfuric acid or dilute hydrochloric acid is 5% to 40%.