Method for Recycling Valuable Metals from Copper Smelting Electric Dust Ash and High-Arsenic Materials

Abstract

The present invention belongs to the field of metallurgical technology and relates to a method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, which comprises the following steps: S1 adding dilute sulfuric acid, activated carbon, ferric sulfate and an oxidant to the copper smelting electric dust ash, and after reaction, performing solid-liquid separation to obtain an acid leaching residue and an acid leaching solution; S2 mixing the acid leaching residue obtained in step S1 with high-arsenic materials and iron powder, and performing reduction smelting to obtain an arsenic-iron alloy, lead matte, flue gas and smelting slag. The present invention uses activated carbon as a catalyst, which can effectively improve the leaching rate and recovery rate of copper elements, and avoid the existence of copper elements in the acid leaching residue in the form of complex compounds; moreover, during the reduction smelting process of the acid leaching residue and high-arsenic materials, activated carbon can also participate in the reduction of high-arsenic materials as a reducing agent, so that arsenic is recovered in the form of an arsenic-iron alloy, 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 adopts 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 will be 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 residues such as acid sludge generated after the purification of smelting flue gas also contain high concentrations of arsenic elements. If these waste residues 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:

[0006] A method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, comprising the following steps:

[0007] 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 an acid leaching residue and an acid leaching solution;

[0008] S2 Mix the acid leaching residue obtained in step S1 with high-arsenic materials and iron powder, and carry out reduction smelting to obtain an arsenic-iron alloy, lead matte, flue gas and smelting slag.

[0009] Among them, the copper smelting electric dust ash can come from: the soot collected by an electrostatic precipitator in copper pyrometallurgy; the high-arsenic materials are selected from one or more of arsenic sulfide slag, calcium arsenate slag, and ferric arsenate slag.

[0010] 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%.

[0011] Specifically, the arsenic sulfide slag can come from the high-arsenic slag obtained by sulfide precipitation of acidic wastewater in the non-ferrous metal smelting process, and the main components are: the arsenic content is 50 wt%-60 wt%, and the sulfur content is 35 wt%-45 wt%.

[0012] Specifically, the calcium arsenate slag can come from the arsenic-containing slag obtained by treating arsenic-containing alkaline wastewater, and the main components are: the arsenic content is 20 wt%-38 wt%, and the calcium content is 15 wt%-30 wt%.

[0013] Specifically, the ferric arsenate slag can come from the arsenic-containing slag obtained by treating arsenic-containing wastewater, and the main components are: the arsenic content is 30 wt%-38 wt%, and the iron content is 20 wt%-28 wt%.

[0014] The reaction mechanism of the present invention is as follows:

[0015] The present invention uses activated carbon 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 the acid leaching residue and high-arsenic materials, and can react with arsenic in the high-arsenic materials, so that arsenic is recovered in the form of an arsenic-iron alloy.

[0016] In step S1, activated carbon participates in the leaching reactions of Cu3AsS4 and CuFeS2 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 as follows:

[0017] PbO + H2SO4 → PbSO4 + H2O;

[0018] ZnO + H2SO4 → ZnSO4 + H2O;

[0019] CuO + H2SO4 → CuSO4 + H2O;

[0020] Fe2O3 + 3H2SO4 → Fe2(SO4)3 + 3H2O;

[0021] As2O3 + H2O + 2H2O2 → 2H3AsO4;

[0022] 2H3AsO4 + Fe2(SO4)3 → 2FeAsO4↓ + 3H2SO4;

[0023] 2Cu3AsS4 + 35H2O2 + Fe2(SO4)3 → 2FeAsO4↓ + 6CuSO4 + 5H2SO4 + 30H2O;

[0024] 2CuFeS2 + 17H2O2 + H2SO4 → 2CuSO4 + Fe2(SO4)3 + 18H2O.

[0025] Among them, the copper content in the acid leaching residue obtained in step S1 is ≤0.10 wt%.

[0026] 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 copper smelting electric dust ash is (10 - 15):1, the molar ratio of ferric sulfate to the total amount of arsenic in 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 copper smelting electric dust ash is (0.2 - 0.5):1.

[0027] Preferably, in step S1, the reaction temperature is 60 - 80 °C and the reaction time is 2 - 4 h.

[0028] 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%.

[0029] 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.

[0030] In step S2, the activated carbon in the acid leaching residue acts as a reducing agent to participate in the high-temperature reduction of the high-arsenic material. During the reduction process, it can react with the arsenic in the high-arsenic material, enabling the arsenic to be recovered in the form of arsenic-iron alloy. The main reactions are as follows:

[0031] 2C + O2 → 2CO;

[0032] PbSO4 + 4CO → PbS + 4CO2;

[0033] 5Fe + As2S3 → 3FeS + 2FeAs;

[0034] FeAsO4 + 3CO → FeO + As + 3CO2;

[0035] FeO + As + CO → FeAs + CO2;

[0036] Ca3(AsO4)2 + 5CO + 2Fe → 2FeAs + 3CaO + 5CO2.

[0037] Among them, the acid leaching residue can be mixed with the high-arsenic material in any proportion.

[0038] Preferably, in step S2, the reduction smelting temperature is 1150 - 1250 °C, and the time is 3 - 8 h.

[0039] 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 70 wt% - 85 wt%. The mass ratio of the total amount of the carbonaceous reducing agent and the activated carbon in the acid leaching residue to the total amount of arsenic and lead in the mixture of the acid leaching residue and the high-arsenic material is (0.2 - 0.5):1. The carbonaceous reducing agent can supplement the activated carbon in the acid leaching residue and jointly participate in the reduction smelting of the high-arsenic material and the acid leaching residue.

[0040] 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.

[0041] Preferably, in step S2, the flue gas is returned to the flue gas treatment system to recover the electric dust removal ash, and the electric dust removal ash is returned to step S2.

[0042] 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 and gold, silver.

[0043] The beneficial effects of the present invention are as follows:

[0044] 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 ash, and avoid the existence of copper elements in the acid leaching residue in the form of complex compounds. Moreover, during the reduction smelting process of the acid leaching residue and high-arsenic materials, activated carbon and carbonaceous reducing agents participate in the reduction of high-arsenic materials as reducing agents, enabling arsenic to be recovered in the form of arsenic-iron alloy, and the recovery process is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a process flow chart for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials in the specific implementation manner. SPECIFIC IMPLEMENTATION MANNER

[0046] The principles and features of the present invention will be described below in conjunction with examples. The examples given are only for explaining 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 channels unless otherwise specified. Example 1

[0047] A method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, wherein

[0048] The copper smelting electric dust ash comes from the soot collected by the electrostatic precipitator during 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%.

[0049] The high-arsenic material is arsenic acid iron slag, which comes from the arsenic-containing slag obtained by treating arsenic-containing wastewater. The main components are: arsenic content is 35.22 wt%, and iron content is 24.18 wt%.

[0050] The method steps are as follows:

[0051] 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, and granular coconut shell activated carbon (specific surface area is 1000 m 2 / g, with an average particle size of 1.5 mm and a purity of 90%), and hydrogen peroxide with a concentration of 30 wt%, react at 60 °C for 4 h. After the reaction, solid-liquid separation is carried out to obtain acid leaching residue and acid leaching solution. The acid leaching solution is successively returned to the copper recovery system, zinc recovery system, and multi-effect evaporation system 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, the molar ratio of H2O2 to the total amount of arsenic in copper smelting electric dust ash is 10:1, the molar ratio of Fe2(SO4)3 to the total amount of arsenic in copper smelting electric dust ash is 0.8:1, and the mass ratio of activated carbon to the total amount of copper in copper smelting electric dust ash is 0.2:1.

[0052] S2 Mix the acid leaching residue and iron arsenate residue evenly and place them in a smelting furnace. Add coke with a fixed carbon content of 85 wt% and iron powder to the smelting furnace, and 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 successively returned to the lead smelting system and the precious and rare metal smelting system to recover lead ingots, gold ingots, and silver ingots; among them, the total mass ratio of coke and activated carbon in the acid leaching residue to the total amount of arsenic and lead in the mixture of acid leaching residue and iron arsenate residue is 0.5:1, and the molar ratio of iron powder to the total amount of arsenic in iron arsenate residue is 1.5:1. Example 2

[0053] A method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, among which,

[0054] The copper smelting electric dust ash comes from the soot collected by the electrostatic precipitator during 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%.

[0055] The high-arsenic material is arsenic sulfide slag, which comes from the high-arsenic slag obtained by sulfide precipitation of acidic wastewater during non-ferrous metal smelting. The main components are: arsenic content is 59.87 wt%, and sulfur content is 35.47 wt%.

[0056] The method steps are as follows:

[0057] 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, and granular coconut shell activated carbon (specific surface area is 1500 m 2 / g, with an average particle size of 2 mm and a purity of 90%), and hydrogen peroxide with a concentration of 30 wt%. The reaction was carried out at 80 °C for 2 h. After the reaction, the acid leaching residue and the acid leaching solution were obtained by solid-liquid separation. The acid leaching solution was successively returned to the copper recovery system, the zinc recovery system, and the multi-effect evaporation system 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 was 3:1, the molar ratio of H2O2 to the total amount of arsenic in copper smelting electric dust ash was 13:1, the molar ratio of Fe2(SO4)3 to the total amount of arsenic in copper smelting electric dust ash was 1:1, and the mass ratio of activated carbon to the total amount of copper in copper smelting electric dust ash was 0.5:1.

[0058] S2 Mix the acid leaching residue and the arsenic sulfide residue evenly and place them in a smelting furnace. Add bituminous coal with a fixed carbon content of 70 wt% and iron powder to the smelting furnace. Carry out reduction smelting at 1200 °C for 3 h to obtain an 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 successively returned to the lead smelting system and the precious and rare metal smelting system to recover lead ingots, gold ingots, and silver ingots. Among them, the mass ratio of the total amount of bituminous coal and activated carbon in the acid leaching residue to the total amount of arsenic and lead in the mixture of the acid leaching residue and the arsenic sulfide residue is 0.2:1, and the molar ratio of iron powder to the total amount of arsenic in the arsenic sulfide residue is 3:1. Example 3

[0059] A method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, wherein,

[0060] The copper smelting electric dust ash comes from the soot collected by the electrostatic precipitator in 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%.

[0061] 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%.

[0062] The method steps are as follows:

[0063] 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, and granular coconut shell activated carbon (specific surface area is 1200 m 2 / g, with an average particle size of 3 mm and a purity of 95%), and hydrogen peroxide with a concentration of 30 wt%. The reaction was carried out at 70 °C for 3 h. After the reaction, the acid leaching residue and the acid leaching solution were obtained by solid-liquid separation. The acid leaching solution was returned to the copper recovery system, the zinc recovery system, and the 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 was 5:1, the molar ratio of H2O2 to the total amount of arsenic in copper smelting electric dust ash was 15:1, the molar ratio of Fe2(SO4)3 to the total amount of arsenic in copper smelting electric dust ash was 1.2:1, and the mass ratio of activated carbon to the total amount of copper in copper smelting electric dust ash was 0.3:1.

[0064] S2 Mix the acid leaching residue and the calcium arsenate residue evenly and place them in a smelting furnace. Add bituminous coal with a fixed carbon content of 75 wt% and iron powder to the smelting furnace. Carry out reduction smelting at 1250 °C for 5 h to obtain an 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 and rare metal smelting system in sequence to recover lead ingots, gold ingots, and silver ingots. Among them, the mass ratio of the total amount of bituminous coal and activated carbon in the acid leaching residue to the total amount of arsenic and lead in the mixture of the acid leaching residue and the calcium arsenate residue is 0.3:1, and the molar ratio of iron powder to the total amount of arsenic in the calcium arsenate residue is 2:1. Comparative Example 1

[0065] For the specific steps, refer to Example 1, with the difference that: activated carbon is not added in step S1. Comparative Example 2

[0066] For the specific steps, refer to Example 2, with the difference that: activated carbon is not added in step S1. Comparative Example 3

[0067] For the specific steps, refer to Example 3, with the difference that: activated carbon is not added in step S1.

[0068] Test

[0069] Detect the Cu content in the acid leaching residue and the acid leaching solution obtained in 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.

[0070] The copper in the acid leaching residue and the acid leaching solution was detected according to "Methods for Chemical Analysis of Copper Smelting 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).

[0071] Table 1 Cu Content in Acid Leaching Residue and Acid Leaching Solution

[0072] 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

[0073] Table 2 Recovery rate of valuable metals

[0074] 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

[0075] As shown in Table 1 and Table 2, after adding activated carbon as a catalyst in the oxidative acid leaching process of copper smelting electric dust ash, the copper content in the acid leaching solutions obtained in Examples 1-3 is significantly higher than that in Comparative Examples 1-3, the copper content in the acid leaching residues obtained in Examples 1-3 is significantly lower than that in Comparative Examples 1-3, and the copper recovery rates in Examples 1-3 are significantly higher than those in Comparative Examples 1-3, all by more than 4%. This shows that using activated carbon as a catalyst can effectively improve the leaching rate of copper elements in the oxidative acid leaching process of copper smelting electric dust ash.

[0076] 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 principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Method for recovering valuable metals from copper smelting electric dust ash and high-arsenic materials, characterized in that, It includes 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 residue and acid leaching solution; the oxidant is hydrogen peroxide; the mass ratio of the activated carbon to the total amount of copper in the copper smelting electric dust ash is (0.2~0.5):1; S2 Mix the acid leaching residue obtained in step S1 with high-arsenic materials, iron powder and a carbonaceous reducing agent selected from one or more of coke and bituminous coal, and carry out reduction smelting to obtain arsenic-iron alloy, matte, flue gas and smelting slag; the reduction smelting temperature is 1150~1250°C, and the time is 3~8h; the molar ratio of the iron powder to the total amount of arsenic in the high-arsenic materials is (1.5~3.0):

1.

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

1.

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

1.

4. The method according to claim 1, wherein In step S1, 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%.

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

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