A method for treating copper-arsenic slag

Abstract

A method for treating copper-arsenic slag includes the following steps: 1) preliminary screening and preliminary wet ball milling of the copper-arsenic slag; 2) addition of sodium chloride, employing a two-stage process to enhance the permeation system; 3) reaction of the filtered residue with dilute acid; 4) addition of acid to the slag, followed by the addition of an oxidant for further reaction; 5) centrifugation of the reacted liquid, and collection of the leachate; 6) addition of alkali solution to adjust the pH to 3-4, and filtration of the precipitate; 7) addition of hydrogen peroxide to the leachate after precipitate removal, adjusting the pH to 7-8, and filtration of the precipitate; 8) reaction of the filtered precipitate with dilute acid, and collection of the filtrate; 9) adjustment of the pH of the filtrate to above 12, addition of hydrogen peroxide for further reaction, and filtration of the precipitate; 10) calcination of the filtered residue to obtain the product. After treatment by this method, the arsenic content in the copper slag product is reduced to below 3.5%, while the copper content increases to above 80%, with a copper yield exceeding 50%.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal smelting technology, specifically relating to a method for treating copper-arsenic slag. Background Technology

[0002] In the non-ferrous metal smelting industry, copper-arsenic slag is an inevitable industrial byproduct generated during the extraction of copper from copper ore. Its formation stems from the material transformation processes following copper mining, including crushing, flotation, and smelting. After the copper in the ore is selectively separated and extracted, the remaining complex mixture undergoes high-temperature smelting or wet leaching processes, ultimately forming a solid waste slag containing various substances. This type of waste slag exhibits extremely complex and unique composition, enriching it with various recoverable minerals such as copper, iron, sulfur, gold, and silver, while also containing highly toxic and harmful elements such as arsenic, lead, cadmium, and mercury. Arsenic, as a typical highly toxic pollutant, exists stably in the slag in the form of arsenic compounds or arsenic sulfides, becoming the core challenge restricting its treatment and disposal.

[0003] Traditionally, the treatment and disposal of copper-arsenic slag has long been a key challenge in global environmental management. Due to its complex composition, high toxicity, and poor stability, it is easily affected by rainwater leaching and soil infiltration in the natural environment. Harmful elements such as arsenic and heavy metals are gradually released, seeping into groundwater systems or spreading into the soil and atmosphere, causing a series of ecological and environmental problems such as soil heavy metal pollution and groundwater deterioration, posing a serious threat to the integrity of surrounding ecosystems and human health. In the past, the industry generally adopted passive disposal methods such as stockpiling and landfilling, and solidification stabilization. Stockpiling and landfilling require large amounts of land resources and complex anti-seepage and anti-leaching facilities, resulting in high long-term maintenance costs and potential environmental risks. While solidification stabilization can reduce the migration of harmful elements to some extent, it does not fundamentally eliminate pollutants, and the waste still requires long-term safe disposal, which may also generate secondary pollution. These traditional methods are unable to meet increasingly stringent environmental protection requirements, making copper-arsenic slag a prominent bottleneck restricting the green transformation of the copper smelting industry.

[0004] In recent years, with the increasing prominence of global resource shortages and the continuous improvement of ecological and environmental protection awareness, the resource utilization of copper-arsenic slag has become an inevitable trend in the industry. Research and development of related technologies have become a hot topic in the field of comprehensive mineral resource utilization. How to harmlessly treat copper-arsenic slag, transform the harmful element arsenic in the slag into a stable product, fundamentally solve the pollution problem, recover copper from the slag, and avoid resource waste is a pressing research topic. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a method for treating copper-arsenic slag.

[0006] The objective of this invention is achieved through the following technical solution: a method for treating copper-arsenic slag, comprising the following steps: 1) The copper-arsenic slag was initially screened and then preliminarily wet-milled; 2) Add sodium chloride solution to the slag after ball milling and use a two-stage process to enhance the effect of the permeation system. The first stage is ball milling reaction, with a reaction time of more than 2 hours. The second stage is high-temperature ultrasonic reaction, with a reaction time of more than 2 hours. After the reaction, filter out the slag. 3) React the filter residue with dilute acid. The concentration of the dilute acid should be below 1 mol / L, and the reaction time should be more than 2 hours. After the reaction, filter out the residue. 4) Add acid to the residue, then add oxidant, and react for more than 2 hours at a temperature of 50-90℃. 5) Centrifuge the reacted liquid at 3000-5000 r / min for 10-20 min and collect the leachate; 6) Add alkaline solution to adjust the pH to 3-4, then filter out the precipitate; 7) Add hydrogen peroxide to the leachate after filtering out the precipitate, adjust the pH value to 7-8, and filter out the precipitate; 8) Add dilute acid to the filtered precipitate and react for more than 2 hours, then collect the filtrate; 9) Quickly adjust the pH of the filtrate to 8 within 30 minutes, and slowly adjust it to 12 or higher over 2 hours. Add hydrogen peroxide to react, and filter to precipitate after standing for 24 hours. 10) The filtered residue is roasted to obtain copper slag product.

[0007] Furthermore, in step 1), the copper-arsenic slag contains copper with a mass fraction of 10% or more and As with a mass fraction of 5% or more.

[0008] Furthermore, in step 1), the preliminary wet ball milling is carried out to 100 mesh, the ball milling speed is 300-500 r / min, the ball-to-material ratio is 3-5:1, the ball milling time is 1-3 h, and the ball milling is followed by drying at 90°C for 2 h.

[0009] Furthermore, in step 2), the mass concentration of the sodium chloride solution is 5% to 15%; in the high-temperature ultrasonic reaction, the temperature is above 80°C, and the sodium chloride solution is added according to a liquid-to-solid ratio of ≥5 L / kg.

[0010] Furthermore, in step 3), the reaction temperature with the dilute acid is 50-90℃, and the liquid-to-solid ratio is ≥5 L / kg; the dilute acid is 0.5 mol / L dilute sulfuric acid.

[0011] Furthermore, in step 4), the acid is 8 mol / L sulfuric acid; the oxidant is hydrogen peroxide or sodium hypochlorite, the liquid-to-solid ratio is ≥5 L / kg, and the mass ratio of the oxidant added to the slag in this step is 0.5-2:1.

[0012] Furthermore, in step 6), the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution, and the pH value is adjusted to 3.5.

[0013] Furthermore, in step 8), the concentration of dilute acid is below 3 mol / L, the liquid-to-solid ratio is ≥5 L / kg, and the reaction temperature is above 50℃.

[0014] Furthermore, in step 9, the hydrogen peroxide is 30% by mass, the volume ratio of filtrate to hydrogen peroxide is 1:100 or higher, the reaction temperature is 25-50°C, and the reaction time is 2-4 hours.

[0015] Furthermore, in step 10, the calcination temperature is above 500°C and the calcination time is above 30 minutes.

[0016] The beneficial effects of this invention are: after copper arsenic slag is treated by the method of this invention, the arsenic content in the product copper slag is reduced to below 3.5%, while the copper content in the product copper slag is increased to more than 80%, and the copper yield reaches more than 50%. Detailed Implementation

[0017] The present invention will now be described in detail.

[0018] Experimental Example 1 Take copper-arsenic slag, in which the mass fraction of copper is 26.45% and the mass fraction of arsenic is 16%, and treat the copper-arsenic slag using the following steps; 1) The copper-arsenic slag was initially wet-milled to 100 mesh at a milling speed of 300 r / min, a ball-to-material ratio of 3:1, a milling time of 3 h, and then dried at 90 °C for 2 h after milling. 2) Add a 10% sodium chloride solution with a liquid-to-solid ratio of 6 L / kg and use a two-stage process to enhance the permeation system. The first stage is a ball milling reaction with a reaction time of 4 hours, and the second stage is a high-temperature ultrasonic reaction at 80℃ for 4 hours. After the reaction, filter out the residue. 3) The filter residue reacted with 0.5 mol / L dilute sulfuric acid for 4 hours at a reaction temperature of 90℃ and a liquid-to-solid ratio of 5 L / kg. The residue was then filtered out after the reaction. 4) Add 8 mol / L sulfuric acid to the slag, then add sodium hypochlorite as an oxidant. The ratio of sodium hypochlorite to solid slag is 1:1. React for 4 hours, with a liquid-to-solid ratio of 10 L / kg and a reaction temperature of 50℃. 5) Centrifuge the reacted liquid at 3000 r / min for 20 min and collect the leachate; 6) Add sodium hydroxide solution to adjust the pH to 3.5 and filter out the precipitate; 7) Add 30% hydrogen peroxide to the leachate after filtering out the precipitate, continue to adjust the pH value to 7.5, and filter out the precipitate; 8) Add 2 mol / L nitric acid to the filtered precipitate, with a liquid-to-solid ratio of 5 L / kg, react for 4 h, and the reaction temperature is 80℃; 9) After the reaction, the pH of the filtrate is quickly adjusted to 8 within 25 minutes, and then slowly adjusted to 14 over 2.5 hours. 30% hydrogen peroxide is added, with a volume ratio of filtrate to hydrogen peroxide of 1:30. The reaction temperature is 25°C and the reaction time is 4 hours. After standing for 24 hours, the precipitate is filtered. 10) The filtered precipitate was roasted at 600℃ for 2 hours to obtain copper slag product.

[0019] Experimental Example 2 Take copper-arsenic slag, in which the mass fraction of copper is 32.45% and the mass fraction of As is 18.22%, and treat the copper-arsenic slag using the following steps; 1) Wet ball mill the copper arsenic slag to 100 mesh, with a ball milling speed of 500 r / min, a ball-to-material ratio of 5:1, a ball milling time of 1 h, and then dry it at 90℃ for 2 h after ball milling; 2) Add 5% sodium chloride solution with a liquid-to-solid ratio of 5 L / kg and use a two-stage process to enhance the permeation system. The first stage is ball milling reaction with a reaction time of 3 hours, and the second stage is high-temperature ultrasonic reaction at 90℃ for 3 hours. After the reaction, filter out the residue. 3) The filter residue reacted with 0.8 mol / L dilute sulfuric acid for 3 hours at a reaction temperature of 70°C and a liquid-to-solid ratio of 6 L / kg. The residue was then filtered out after the reaction. 4) Add 8 mol / L sulfuric acid to the slag, then add sodium hypochlorite as an oxidant. The ratio of sodium hypochlorite to solid slag is 1:1. React for 3 hours with a liquid-to-solid ratio of 5 L / kg. The reaction temperature is 90℃. 5) Centrifuge the reacted liquid at 5000 r / min for 10 min and collect the leachate; 6) Add potassium hydroxide solution, adjust the pH to 3, and filter out the precipitate; 7) Add 30% hydrogen peroxide to the leachate after filtering out the precipitate, continue to adjust the pH value to 7, and filter out the precipitate; 8) Add 3 mol / L nitric acid to the filtered precipitate, with a liquid-to-solid ratio of 6 L / kg, react for 3 h, and the reaction temperature is 60℃; 9) After the reaction, the pH of the filtrate is rapidly adjusted to 8 within 19 minutes, and then slowly adjusted to 12 over 3 hours. 30% hydrogen peroxide is added, with a volume ratio of filtrate to hydrogen peroxide of 1:100. The reaction temperature is 50℃, the reaction time is 2 hours, and the mixture is allowed to stand for 24 hours before filtration and precipitation. 10) The filtered precipitate was roasted at 550℃ for 1 hour to obtain copper slag product.

[0020] Experimental Example 3 Take copper-arsenic slag, in which the mass fraction of copper is 41.12% and the mass fraction of As is 17.95%, and treat the copper-arsenic slag using the following steps; 1) Wet ball mill the copper arsenic slag to 100 mesh, with a ball milling speed of 400 r / min, a ball-to-material ratio of 4:1, a ball milling time of 2 h, and then dry it at 90 °C for 2 h after ball milling; 2) Add a 15% sodium chloride solution with a liquid-to-solid ratio of 7 L / kg and use a two-stage process to enhance the permeation system. The first stage is a ball milling reaction with a reaction time of 2 hours, and the second stage is a high-temperature ultrasonic reaction at 100℃ for 2 hours. After the reaction, filter out the residue. 3) The filter residue reacted with 1 mol / L dilute sulfuric acid for 2 hours at a reaction temperature of 50°C and a liquid-to-solid ratio of 7 L / kg. The residue was then filtered out after the reaction. 4) Add 8 mol / L sulfuric acid to the slag, then add 30% hydrogen peroxide as the oxidant. The ratio of hydrogen peroxide to solid slag is 1:1. React for 2 hours. The liquid-to-solid ratio is 8 L / kg. The reaction temperature is 70℃. 5) Centrifuge the reacted liquid at 4000 r / min for 15 min and collect the leachate; 6) Add sodium hydroxide solution, adjust the pH to 4, and filter out the precipitate; 7) Add 30% hydrogen peroxide to the leachate after filtering out the precipitate, continue to adjust the pH value to 8, and filter out the precipitate; 8) Add 2.5 mol / L nitric acid to the filtered precipitate, with a liquid-to-solid ratio of 7 L / kg, react for 2 h at a reaction temperature of 50℃; 9) After the reaction, the pH of the filtrate is rapidly adjusted to 8 within 22 minutes, and then slowly adjusted to 13 over 3.4 hours. 30% hydrogen peroxide is added, with a volume ratio of filtrate to hydrogen peroxide of 1:50. The reaction temperature is 40℃ and the reaction time is 3 hours. After standing for 24 hours, the precipitate is filtered. 10) The filtered precipitate is roasted at 500℃ for 30 minutes to obtain copper slag product.

[0021] Comparative Example 1 This comparative example omits step 2 of the reaction. The copper-arsenic slag after ball milling in step 1 is directly reacted with dilute sulfuric acid in step 3. The remaining steps are the same as in Experimental Example 1. This comparative example does not perform enhanced permeation in step 2, and the permeation channels of the subsequent reaction solution are not fully opened.

[0022] Comparative Example 2 In this comparative example, no oxidant was added in step 4, and the remaining steps were the same as in Experimental Example 1. Because no oxidant was added in step 4, the As reactivity in this comparative example was weak, resulting in poor removal capacity.

[0023] Comparative Example 3 This comparative example omits step 8. The leachate, after adjusting the pH to 7.5 in step 7, proceeds directly to step 9. The remaining steps are identical to those in Experimental Example 1. Because step 8 is omitted in this comparative example, Cu and As separation was not effectively achieved.

[0024] The contents of copper and arsenic in the copper slag and the copper and arsenic in the copper slag obtained from the above experiments are shown in Table 1.

[0025] Table 1

[0026] As shown in Table 1, after treatment with copper-arsenic slag in Examples 1-3, the arsenic content in the resulting copper slag was reduced to below 3.5%, while the copper content increased to over 80%, and the copper yield reached over 50%. In contrast, in Comparative Examples 1-3, due to changes in the process method, the copper content in the resulting copper slag was below 70%, and the arsenic content was above 10%, failing to meet the process requirements.

[0027] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for treating copper-arsenic slag, characterized in that... Includes the following steps: 1) The copper-arsenic slag was initially screened and then preliminarily wet-milled; 2) Add sodium chloride solution to the slag after ball milling and use a two-stage process to enhance the effect of the permeation system. The first stage is ball milling reaction, with a reaction time of more than 2 hours. The second stage is high-temperature ultrasonic reaction, with a reaction time of more than 2 hours. After the reaction, filter out the slag. 3) React the filter residue with dilute acid. The concentration of the dilute acid should be below 1 mol / L, and the reaction time should be more than 2 hours. After the reaction, filter out the residue. 4) Add acid to the residue, then add oxidant, and react for more than 2 hours at a temperature of 50-90℃. 5) Centrifuge the reacted liquid at 3000-5000 r / min for 10-20 min and collect the leachate; 6) Add alkaline solution to adjust the pH to 3-4, then filter out the precipitate; 7) Add hydrogen peroxide to the leachate after filtering out the precipitate, adjust the pH value to 7-8, and filter out the precipitate; 8) Add dilute acid to the filtered precipitate and react for more than 2 hours, then collect the filtrate; 9) Quickly adjust the pH of the filtrate to 8 within 30 minutes, and slowly adjust it to 12 or higher over 2 hours. Add hydrogen peroxide to react, and filter to precipitate after standing for 24 hours. 10) The filtered residue is roasted to obtain copper slag product.

2. The method for treating copper-arsenic slag according to claim 1, characterized in that: In step 1), the copper-arsenic slag contains copper with a mass fraction of 10% or more and As with a mass fraction of 5% or more.

3. The method for treating copper-arsenic slag according to claim 1, characterized in that: In step 1), the preliminary wet ball milling is carried out to 100 mesh, the ball milling speed is 300-500 r / min, the ball-to-material ratio is 3-5:1, the ball milling time is 1-3 h, and the ball milling is followed by drying at 90°C for 2 h.

4. The method for treating copper-arsenic slag according to claim 1, characterized in that: In step 2), the mass concentration of the sodium chloride solution is 5% to 15%; in the high-temperature ultrasonic reaction, the temperature is above 80°C, and the sodium chloride solution is added according to a liquid-to-solid ratio of ≥5 L / kg.

5. The method for treating copper-arsenic slag according to claim 1, characterized in that: In step 3), the reaction with dilute acid is carried out at a temperature of 50-90℃ and a liquid-to-solid ratio of ≥5 L / kg; the dilute acid is 0.5 mol / L dilute sulfuric acid.

6. The method for treating copper-arsenic slag according to claim 1, characterized in that: In step 4), the acid is 8 mol / L sulfuric acid; the oxidant is hydrogen peroxide or sodium hypochlorite, the liquid-to-solid ratio is ≥5 L / kg, and the mass ratio of the oxidant added to the slag in this step is 0.5-2:

1.

7. The method for treating copper-arsenic slag according to claim 1, characterized in that: In step 6), the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution, and the pH value is adjusted to 3.

5.

8. The method for treating copper-arsenic slag according to claim 1, characterized in that: In step 8), the concentration of dilute acid is below 3 mol / L, the liquid-to-solid ratio is ≥5 L / kg, and the reaction temperature is above 50℃.

9. The method for treating copper-arsenic slag according to claim 1, characterized in that: In step 9, the hydrogen peroxide is 30% by mass, the volume ratio of filtrate to hydrogen peroxide is 1:100 or higher, the reaction temperature is 25-50℃, and the reaction time is 2-4 hours.

10. A method for treating copper-arsenic slag according to claim 1, characterized in that: In step 10, the calcination temperature is above 500°C and the calcination time is above 30 minutes.

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