Method for recovering valuable metals from copper smelting electric dust and high-arsenic material

Abstract

The invention belongs to the technical field of metallurgy, and relates to a method for recovering valuable metals from copper smelting electric dust and a high-arsenic material, which comprises the following steps: S1, adding dilute sulphuric acid, activated carbon, ferric sulfate and an oxidant into the copper smelting electric dust, and after reaction, carrying out solid-liquid separation to obtain acid leaching residues and acid leaching liquid; and S2, the acid leaching residues obtained in the step S1 are mixed with a high-arsenic material and iron powder, reduction smelting is carried out, and arsenic-iron alloy, lead matte, flue gas and smelting slag are obtained. Activated carbon is used as a catalyst, the leaching rate and the recovery rate of the copper element can be effectively increased, and the copper element is prevented from existing in the acid leaching residues in the form of complex compounds; and moreover, in the reduction smelting process of the acid leaching residues and the high-arsenic material, the activated carbon can also be used as a reducing agent to participate in reduction of the high-arsenic material, so that the arsenic is recovered in an arsenic-iron alloy form, and the recovery process is simple.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgy, and particularly relates to a method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials. Background Art

[0002] Copper smelting electric dust ash mainly comes from the flue gas treatment system in the copper pyrometallurgy process. Its elemental composition is quite complex and will vary due to differences in ore sources and smelting technologies. Generally, it contains various metal elements such as copper, zinc, lead, arsenic, bismuth, iron, silver, antimony, etc., and is thus classified as hazardous solid waste. The processes for treating these electric dust ashes mainly include wet processes, pyrometallurgical processes, and combined wet-pyrometallurgical treatment processes; in the wet process, the copper removal process usually uses acid leaching or oxidative acid leaching methods, which can effectively dissolve most of the copper in the electric dust ash. However, there is still some copper present in the form of complex compounds and is difficult to be effectively leached, which limits the overall recovery rate of copper.

[0003] The main sources of arsenic-containing hazardous wastes in the non-ferrous industry include: (1) During the smelting process, arsenic elements in the ore are released along with waste residues and soot emissions, forming arsenic-containing hazardous wastes. For example, during the copper smelting process, a large amount of arsenic-containing waste residues are generated. If these waste residues are not properly treated, they will pose a serious threat to the environment and human health. (2) During the acid-making process, waste materials such as acid sludge generated after the purification of smelting flue gas also contain high concentrations of arsenic elements. If these waste materials are not properly treated, they will also cause harm to the environment and the ecosystem. (3) When treating arsenic-containing wastewater, the method of adding sulfiding agents or lime for neutralization is usually adopted, thus generating arsenic-containing waste residues. Arsenic-containing wastes are usually treated by pyrometallurgical or wet processes, and the arsenic in them is usually recovered in the form of arsenic trioxide or solidified in the form of scorodite. As a typical hazardous waste, arsenic trioxide has limited market demand and is difficult to store; while scorodite may release arsenic due to weathering or oxidation in the natural environment, resulting in long-term pollution of soil or water bodies. For example, its weathering products may dissolve in acidic groundwater, thereby causing the migration and diffusion of arsenic. In contrast, arsenic iron alloy is widely used in fields such as counterweight, and is simple to store; therefore, recovering arsenic in the form of arsenic iron alloy has important practical significance. Summary of the Invention

[0004] In view of the above deficiencies in the prior art, the present invention provides a method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, which can effectively leach the copper element in the electric dust ash, avoid the copper element existing in the acid leaching residue in the form of complex compounds, resulting in low copper leaching rate and low recovery rate, and affecting the purity and recovery rate of valuable metals during the recovery process; and can recover the arsenic element in the high-arsenic materials in the form of arsenic iron alloy, with a simple recovery process and convenient storage.

[0005] The specific technical solution is as follows: A method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, comprising the following steps: S1 Add dilute sulfuric acid, activated carbon, ferric sulfate and an oxidant to the copper smelting electric dust ash. After the reaction, solid-liquid separation is carried out to obtain acid leaching residues and acid leaching solutions; S2 Mix the acid leaching residues obtained in step S1 with high-arsenic materials and iron powder, and carry out reduction smelting to obtain ferrous arsenide alloy, lead matte, flue gas and smelting slag.

[0006] Among them, the copper smelting electric dust ash can come from: the soot collected by the electrostatic precipitator during copper pyrometallurgy; the high-arsenic materials are selected from one or more of arsenic sulfide slag, calcium arsenate slag, and ferric arsenate slag.

[0007] Specifically, in the copper smelting electric dust ash: the Au content is 5-20 g / t, the Ag content is 50-200 g / t, the Cu content is 5 wt%-10 wt%, the Pb content is 25 wt%-35 wt%, the Zn content is 5 wt%-10 wt%, the Fe content is 1 wt%-3 wt%, and the As content is 5 wt%-10 wt%.

[0008] Specifically, the arsenic sulfide slag can come from the high-arsenic slag obtained by sulfide precipitation of acidic wastewater during non-ferrous metal smelting. The main components are: the arsenic content is 50 wt%-60 wt%, and the sulfur content is 35 wt%-45 wt%.

[0009] Specifically, the calcium arsenate slag can come from the arsenic-containing slag obtained by treating arsenic-containing alkaline wastewater. The main components are: the arsenic content is 20 wt%-38 wt%, and the calcium content is 15 wt%-30 wt%.

[0010] Specifically, the ferric arsenate slag can come from the arsenic-containing slag obtained by treating arsenic-containing wastewater. The main components are: the arsenic content is 30 wt%-38 wt%, and the iron content is 20 wt%-28 wt%.

[0011] The reaction mechanism of the present invention is as follows: In the present invention, activated carbon is used as a catalyst, which can effectively improve the leaching rate of copper elements during the oxidative acid leaching of copper smelting electric dust ash; moreover, activated carbon acts as a reducing agent during the reduction smelting of acid leaching residues and high-arsenic materials, and can react with arsenic in the high-arsenic materials, so that arsenic is recovered in the form of ferrous arsenide alloy.

[0012] In step S1, activated carbon participates in the leaching reaction of Cu 3 AsS 4 、CuFeS 2 as a catalyst, which can effectively improve the leaching rate of copper elements in copper smelting electric dust ash; the oxidant is preferably hydrogen peroxide (hydrogen peroxide). The main reactions are: PbO + H 2 SO 4 → PbSO 4 + H 2 O; ZnO + H 2 SO 4 → ZnSO 4 + H 2 O; CuO + H 2 SO 4 → CuSO 4 + H 2 O; Fe 2 O 3 + 3H 2 SO 4 → Fe 2 (SO 4 ) 3 + 3H 2 O; As 2 O 3 + H 2 O + 2H 2 O 2 → 2H 3 AsO 4 ; 2H 3 AsO 4 + Fe 2 (SO 4 ) 3 → 2FeAsO 4 ↓ + 3H 2 SO 4 ; 2Cu 3 AsS 4 + 35H 2 O 2 + Fe 2 (SO 4 ) 3 → 2FeAsO 4 ↓ + 6CuSO 4 + 5H 2 SO 4 + 30H 2 O; 2CuFeS 2 + 17H 2 O 2 + H 2 SO 4 → 2CuSO 4 + Fe 2 (SO 4 )3 +18H 2 O.

[0013] Among them, the copper content in the acid leaching residue obtained in step S1 is ≤ 0.10 wt%.

[0014] Preferably, the concentration of dilute sulfuric acid is 100 - 200 g / L, the liquid-solid mass ratio of dilute sulfuric acid to copper smelting electric dust ash is (3 - 6):1, the molar ratio of the oxidant to the total amount of arsenic in the copper smelting electric dust ash is (10 - 15):1, the molar ratio of ferric sulfate to the total amount of arsenic in the copper smelting electric dust ash is (0.8 - 1.2):1, and the mass ratio of activated carbon to the total amount of copper in the copper smelting electric dust ash is (0.2 - 0.5):1.

[0015] Preferably, in step S1, the reaction temperature is 60 - 80 °C and the reaction time is 2 - 4 h.

[0016] Preferably, the activated carbon is granular coconut shell activated carbon, with a specific surface area of 1000 - 1500 m 2 / g, an average particle size of 1.5 - 3 mm, and a purity of ≥ 90%.

[0017] Preferably, in step S1, the acid leaching solution is sequentially returned to the copper recovery system, zinc recovery system, and multi-effect evaporation system to recover copper, zinc, and sodium sulfate.

[0018] In step S2, the activated carbon in the acid leaching residue participates in the high-temperature reduction of the high-arsenic material as a reducing agent, and can react with the arsenic in the high-arsenic material during the reduction process, so that the arsenic is recovered in the form of arsenic-iron alloy. The main reactions are: 2C + O 2 → 2CO; PbSO 4 + 4CO → PbS + 4CO 2 ; 5Fe + As 2 S 3 → 3FeS + 2FeAs; FeAsO 4 + 3CO → FeO + As + 3CO 2 ; FeO + As + CO → FeAs + CO 2 ; Ca 3 (AsO 4 ) 2 + 5CO + 2Fe → 2FeAs + 3CaO + 5CO 2 .

[0019] Among them, the acid leaching residue can be mixed with the high-arsenic material in any proportion.

[0020] Preferably, in step S2, the reduction smelting temperature is 1150~1250 °C, and the time is 3~8 h.

[0021] Preferably, in step S2, a carbonaceous reducing agent is further added. The carbonaceous reducing agent is selected from one or more of coke and bituminous coal. The fixed carbon content of the carbonaceous reducing agent is 70wt%~85wt%. The mass ratio of the total amount of the carbonaceous reducing agent and activated carbon in the acid-leached residue to the total amount of arsenic and lead in the mixture of the acid-leached residue and the high-arsenic material is (0.2~0.5):1. The carbonaceous reducing agent can supplement the activated carbon in the acid-leached residue and jointly participate in the reduction smelting of the high-arsenic material and the acid-leached residue.

[0022] Preferably, in step S2, the molar ratio of iron powder to the total amount of arsenic in the high-arsenic material is (1.5~3.0):1.

[0023] Preferably, in step S2, the flue gas is returned to the flue gas treatment system to recover the electric dust, and the electric dust is returned to step S2.

[0024] In step S2, the matte, mainly composed of lead and sulfur, contains a small amount of gold, silver, etc. Preferably, the matte is sequentially returned to the lead smelting system and the precious and rare metal smelting system to recover lead, gold, and silver.

[0025] The beneficial effects of the present invention are as follows: The present invention uses activated carbon as a catalyst, which can effectively improve the leaching rate and recovery rate of copper elements during the oxidative acid leaching process of copper smelting electric dust, and avoid the existence of copper elements in the form of complex compounds in the acid-leached residue; moreover, during the reduction smelting process of the acid-leached residue and the high-arsenic material, the activated carbon and the carbonaceous reducing agent participate in the reduction of the high-arsenic material as reducing agents, so that arsenic is recovered in the form of arsenic-iron alloy, and the recovery process is simple. Description of the Drawings

[0026] Figure 1 It is a process flow chart for recovering valuable metals from copper smelting electric dust and high-arsenic materials in the specific implementation manner. Specific Embodiments

[0027] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified. Example 1

[0028] A method for recovering valuable metals from copper smelting electric dust and high-arsenic materials, wherein The copper smelting electric dust ash comes from the soot collected by the electrostatic precipitator in copper pyrometallurgy. The main component contents are: Au: 5.02 g / t, Ag: 50.42 g / t, Cu: 9.89 wt%, Pb: 25.41 wt%, Zn: 5.21 wt%, Fe: 2.87 wt%, As: 9.89 wt%. The high-arsenic material is ferric arsenate slag, which comes from the arsenic-containing slag obtained from the treatment of arsenic-containing wastewater. The main components are: arsenic content is 35.22 wt%, and iron content is 24.18 wt%.

[0029] The method steps are as follows: S1 Place the copper smelting electric dust ash in a reaction tank, and slowly add dilute sulfuric acid with a concentration of 100 g / L, ferric sulfate, granular coconut shell activated carbon (specific surface area is 1000 m 2 / g, average particle size is 1.5 mm, purity is 90%) and hydrogen peroxide with a concentration of 30 wt% into the reaction tank. React at 60 °C for 4 h. After the reaction is completed, obtain the acid leaching residue and acid leaching solution through solid-liquid separation. The acid leaching solution is returned to the copper recovery system, zinc recovery system, and multi-effect evaporation system in sequence to obtain cathode copper, zinc ingots, and sodium sulfate; among them, the liquid-solid mass ratio of dilute sulfuric acid to copper smelting electric dust ash is 6:1, and the molar ratio of H 2 O 2 to the total amount of arsenic in the copper smelting electric dust ash is 10:1, and the molar ratio of Fe 2 (SO 4 ) 3 to the total amount of arsenic in the copper smelting electric dust ash is 0.8:1, and the mass ratio of activated carbon to the total amount of copper in the copper smelting electric dust ash is 0.2:1.

[0030] S2 Mix the acid leaching residue and ferric arsenate slag evenly, and place them in a smelting furnace. Add coke with a fixed carbon content of 85 wt% and iron powder into the smelting furnace. Carry out reduction smelting at 1150 °C for 8 h to obtain arsenic-iron alloy, lead matte, flue gas, and smelting slag. The flue gas is returned to the flue gas treatment system to recover electric dust ash and returned to step S2 for reduction smelting, and the rest of the impurities are discharged. The lead matte is returned to the lead smelting system and precious metal smelting system in sequence to recover lead ingots, gold ingots, and silver ingots; among them, the total amount of coke and activated carbon in the acid leaching residue and the mass ratio of arsenic and lead in the mixture of acid leaching residue and ferric arsenate slag is 0.5:1, and the molar ratio of iron powder to the total amount of arsenic in ferric arsenate slag is 1.5:1. Example 2

[0031] A method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, wherein, Copper smelting electric dust ash comes from the soot collected by the electrostatic precipitator in copper pyrometallurgy. The main component contents are: Au: 19.58 g / t, Ag: 199.21 g / t, Cu: 5.41 wt%, Pb: 34.86 wt%, Zn: 5.32 wt%, Fe: 1.26 wt%, As: 5.31 wt%.

[0032] The high-arsenic material is arsenic sulfide slag, which comes from the high-arsenic slag obtained by sulfide precipitation of acidic wastewater in the non-ferrous metal smelting process. The main components are: arsenic content is 59.87 wt%, and sulfur content is 35.47 wt%.

[0033] The method steps are as follows: S1 Place the copper smelting electric dust ash in a reaction tank, and slowly add dilute sulfuric acid with a concentration of 200 g / L, ferric sulfate, granular coconut shell activated carbon (specific surface area is 1500 m 2 / g, average particle size is 2 mm, purity is 90%) and hydrogen peroxide with a concentration of 30 wt% into the reaction tank. React at 80 °C for 2 h. After the reaction ends, obtain acid-leached residue and acid-leached solution through solid-liquid separation. The acid-leached solution is returned to the copper recovery system, zinc recovery system, and multi-effect evaporation system in turn to obtain cathode copper, zinc ingots, and sodium sulfate; among them, the liquid-solid mass ratio of dilute sulfuric acid to copper smelting electric dust ash is 3:1, and the molar ratio of H 2 O 2 to the total amount of arsenic in the copper smelting electric dust ash is 13:1, and the molar ratio of Fe 2 (SO 4 ) 3 to the total amount of arsenic in the copper smelting electric dust ash is 1:1, and the mass ratio of activated carbon to the total amount of copper in the copper smelting electric dust ash is 0.5:1.

[0034] S2 Mix the acid-leached residue and arsenic sulfide slag evenly, and place them in a smelting furnace. Add bituminous coal with a fixed carbon content of 70 wt% and iron powder into the smelting furnace. Carry out reduction smelting at 1200 °C for 3 h to obtain arsenic-iron alloy, lead matte, flue gas, and smelting slag. The flue gas is returned to the flue gas treatment system to recover electric dust ash and returned to step S2 for reduction smelting. The rest of the impurities are discharged. The lead matte is returned to the lead smelting system and precious metal smelting system in turn to recover lead ingots, gold ingots, and silver ingots; among them, the total amount of bituminous coal and activated carbon in the acid-leached residue and the mass ratio of arsenic and lead in the mixture of acid-leached residue and arsenic sulfide slag is 0.2:1, and the molar ratio of iron powder to the total amount of arsenic in the arsenic sulfide slag is 3:1. Example 3

[0035] A method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, wherein, The copper smelting electric dust ash comes from the soot collected by the electrostatic precipitator during copper pyrometallurgy. The main component contents are: Au: 10.25 g / t, Ag: 121.24 g / t, Cu: 6.58 wt%, Pb: 31.21 wt%, Zn: 7.82 wt%, Fe: 2.31 wt%, As: 8.64 wt%. The high-arsenic material is calcium arsenate slag, which comes from the arsenic-containing slag obtained by treating arsenic-containing alkaline wastewater. The main components are: arsenic content is 36.58 wt%, and calcium content is 29.24 wt%.

[0036] The method steps are as follows: S1 Place the copper smelting electric dust ash in a reaction tank, and slowly add dilute sulfuric acid with a concentration of 150 g / L, ferric sulfate, granular coconut shell activated carbon (specific surface area is 1200 m 2 / g, average particle size is 3 mm, purity is 95%) and hydrogen peroxide with a concentration of 30 wt% into the reaction tank. React at 70 °C for 3 h. After the reaction ends, obtain the acid leaching residue and the acid leaching solution through solid-liquid separation. The acid leaching solution is returned to the copper recovery system, zinc recovery system, and multi-effect evaporation system in turn to obtain cathode copper, zinc ingots, and sodium sulfate; among them, the liquid-solid mass ratio of dilute sulfuric acid to copper smelting electric dust ash is 5:1, and the molar ratio of H 2 O 2 to the total amount of arsenic in the copper smelting electric dust ash is 15:1, and the molar ratio of Fe 2 (SO 4 ) 3 to the total amount of arsenic in the copper smelting electric dust ash is 1.2:1, and the mass ratio of activated carbon to the total amount of copper in the copper smelting electric dust ash is 0.3:1.

[0037] S2 Mix the acid leaching residue and calcium arsenate slag evenly, and place them in a smelting furnace. Add bituminous coal with a fixed carbon content of 75 wt% and iron powder into the smelting furnace. Carry out reduction smelting at 1250 °C for 5 h to obtain arsenic-iron alloy, lead matte, flue gas, and smelting slag. The flue gas is returned to the flue gas treatment system to recover electric dust ash and returned to step S2 for reduction smelting, and the rest of the impurities are discharged. The lead matte is returned to the lead smelting system and the precious metal smelting system in turn to recover lead ingots, gold ingots, and silver ingots; among them, the total amount of bituminous coal and activated carbon in the acid leaching residue and the mass ratio of the total amount of arsenic and lead in the mixture of acid leaching residue and calcium arsenate slag is 0.3:1, and the molar ratio of iron powder to the total amount of arsenic in calcium arsenate slag is 2:1. Comparative Example 1

[0038] The specific steps refer to Example 1, the difference is: activated carbon is not added in step S1. Comparative Example 2

[0039] The specific steps refer to Example 2, the difference is: activated carbon is not added in step S1. Comparative Example 3

[0040] For the specific steps, refer to Example 3, with the difference that activated carbon is not added in step S1. Test

[0041] Detect the Cu content in the acid leaching residues and acid leaching solutions obtained from Examples 1 to 3 and Comparative Examples 1 to 3. The results are shown in Table 1; calculate the recovery rates of various valuable metals in Examples 1 to 3 and Comparative Examples 1 to 3. The results are shown in Table 2.

[0042] The copper in the acid leaching residues and acid leaching solutions was detected according to "Methods for Chemical Analysis of Copper Smelting Flue Dust - Part 10: Determination of Copper, Lead, Zinc, Bismuth, Arsenic, Indium, Silver, Cadmium, Antimony, Calcium, Magnesium and Iron Contents - Inductively Coupled Plasma Atomic Emission Spectrometry" (YS / T 1512.10 - 2022).

[0043] Table 1 Cu content in acid leaching residues and acid leaching solutions Cu content Example 1 Comparative Example 1 Example 2 Comparative Example 2 Example 3 Comparative Example 3 Acid leaching solution (g / L) 16.45 13.24 18.02 15.87 13.14 11.27 Acid leaching residue (wt%) 0.05 0.21 0.07 0.24 0.04 0.18

[0044] Table 2 Recovery rates of valuable metals Total recovery rate (%) Example 1 Comparative Example 1 Example 2 Comparative Example 2 Example 3 Comparative Example 3 Au 98.52 98.53 98.60 98.57 98.54 98.59 Ag 98.69 98.54 98.62 98.67 98.59 98.62 Cu 98.55 94.26 98.62 93.25 98.57 92.98 Pb 97.21 97.18 97.18 97.21 97.19 97.20 As 97.28 97.24 97.27 97.24 97.31 97.25 As shown in Table 1 and Table 2, after adding activated carbon as a catalyst during the oxidative acid leaching of copper smelting electric dust ash, the copper content in the acid leaching solutions obtained from Examples 1 to 3 is significantly higher than that in Comparative Examples 1 to 3, the copper content in the acid leaching residues obtained from Examples 1 to 3 is significantly lower than that in Comparative Examples 1 to 3, and the copper recovery rates of Examples 1 to 3 are significantly higher than those of Comparative Examples 1 to 3, all being more than 4% higher. This shows that using activated carbon as a catalyst can effectively improve the leaching rate of copper elements during the oxidative acid leaching of copper smelting electric dust ash.

[0045] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for recovering valuable metals from copper smelting dust and high-arsenic materials, characterized in that: The steps include: S1: Add dilute sulfuric acid, activated carbon, ferric sulfate and oxidant to the copper smelting electric dust ash, and after the reaction, separate the solid and liquid to obtain acid leaching residue and acid leaching liquid; S2: The acid leaching residue obtained in step S1 is mixed with high-arsenic materials and iron powder, and reduction smelting is performed to obtain ferroarsenic alloy, lead matte, flue gas and smelting slag.

2. The method according to claim 1, characterized in that In step S1, the concentration of dilute sulfuric acid is 100-200 g / L, and the liquid-solid mass ratio of dilute sulfuric acid to copper smelting electrostatic ash is (3-6):

1.

3. The method according to claim 1, characterized in that In step S1, the molar ratio of the oxidant to the total amount of arsenic in the copper smelting electrostatic ash is (10-15):1, and the molar ratio of ferric sulfate to the total amount of arsenic in the copper smelting electrostatic ash is (0.8-1.2):

1.

4. The method according to claim 1, characterized in that In step S1, the mass ratio of activated carbon to the total amount of copper in copper smelting electrostatic ash is (0.2~0.5):

1.

5. The method according to claim 1, characterized in that In step S1, the activated carbon is granular coconut shell activated carbon with a specific surface area of ​​1000-1500m 2 / g, average particle size is 1.5~3mm, purity is ≥90%.

6. The method according to claim 1, characterized in that In step S2, the reduction smelting temperature is 1150-1250°C and the time is 3-8 hours.

7. The method according to claim 1, characterized in that In step S2, the molar ratio of iron powder to the total amount of arsenic in the high-arsenic material is (1.5-3.0):

1.

8. The method according to claim 1, characterized in that In step S2, a carbonaceous reducing agent is also added.

9. The method according to claim 8, characterized in that The carbonaceous reducing agent is selected from one or more of coke and bituminous coal.

10. The method according to claim 9, characterized in that The mass ratio of the total amount of activated carbon in the carbonaceous reducing agent and acid leaching residue to the total amount of arsenic and lead in the high-arsenic material and acid leaching residue is (0.2~0.5):1.

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