Method for enriching copper from copper smelting waste acid stock solution

Abstract

The invention discloses a method for enriching copper from a copper smelting waste acid stock solution, and belongs to the technical field of nonferrous metallurgy and environmental engineering. The method aims at solving the problems that in the prior art, copper and arsenic are not thoroughly separated, the copper resource recovery rate is low, and arsenic is cyclically accumulated in a system, and the method comprises the core steps that firstly, preliminary vulcanization is conducted, arsenic slag slurry is generated, then arsenic slag and fresh waste acid are subjected to a cyclic reaction, copper ions are selectively precipitated and enriched in the arsenic slag, and the arsenic slag is recycled. And finally, carrying out deep vulcanization on the separated liquid to obtain the low-copper arsenic slag. According to the method, complex activation equipment and accurate metering are not needed, operation is easy and convenient, copper resources can be efficiently recycled, arsenic is effectively removed, and high-value utilization of valuable metal in waste acid and cooperative control over environmental pollution are achieved.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metallurgy and environmental engineering technology, and specifically relates to a method for enriching copper from waste acid raw liquid in copper smelting. Background Technology

[0002] Copper smelting waste acid solution is an inevitable byproduct of wet purification of smelting flue gas. It is characterized by extremely high acidity and contains various heavy metals such as arsenic, copper, lead, and zinc. This type of wastewater is highly toxic and poses a significant environmental risk, necessitating harmless and resource-efficient treatment.

[0003] Currently, the mainstream industrial methods for treating waste acid from copper smelting include lime neutralization, ferric salt-lime coprecipitation, and sulfide precipitation. Lime neutralization is simple to operate, but it produces a large amount of neutralization slag with high water content, resulting in unstable arsenic fixation and the loss of all valuable metals. Ferric salt-lime coprecipitation enhances arsenic fixation by forming ferric arsenate, but it also suffers from large slag volume, difficulty in subsequent iron slag utilization, and the inability to recover valuable metals such as copper. In contrast, sulfide precipitation is a more attractive option due to its advantages such as low precipitate solubility, small slag volume, and fast reaction rate. This method involves adding sodium sulfide, sodium hydrosulfide, or introducing hydrogen sulfide gas to cause heavy metal ions to precipitate as sulfides. However, the traditional sulfidation method can only achieve the co-precipitation of heavy metals, and the resulting mixed sulfidation slag contains copper and arsenic mixed together, which is difficult to separate. More seriously, in order to recover copper from the slag, some companies return the mixed slag with high arsenic and low copper to the pyrometallurgical system. This directly leads to a vicious cycle and continuous enrichment of arsenic in the smelting system, which seriously interferes with the stable operation of the main process and increases subsequent environmental protection costs.

[0004] To address the challenge of separating copper and arsenic, researchers have made numerous improvements to the sulfidation method. Some existing technologies aim for stepwise selective precipitation, i.e., preferential precipitation of copper or arsenic by controlling potential, pH, or introducing special media. These methods have extremely stringent requirements for reaction condition control, limited operational flexibility, and often require the introduction of new reagents or complex equipment, posing challenges to industrial stability and economic viability. Other technical approaches involve subsequent enhanced treatment of the resulting mixed sulfidation slag, attempting to separate and purify copper and arsenic through mechanical activation and disintegration, ultrasonic dispersion, high-temperature and pressure leaching, or the addition of complex organic extractants. While these methods can improve separation efficiency to some extent, they generally suffer from long process flows, high energy and material consumption, large equipment investment, and complex operation, making it difficult to meet the urgent needs of modern smelting enterprises for "low-cost, simplified, and clean production."

[0005] Patent CN105543480B, entitled "A Method for Separating and Enriching Copper and Arsenic from Copper Smelting Waste Acid," discloses a method of first subjecting the waste acid to a sulfidation reaction to obtain sulfidation slag, then activating the sulfidation slag through mechanical ball milling and ultrasonic dispersion, and finally mixing the activated sulfidation slag with fresh waste acid to achieve the separation and enrichment of copper and arsenic. However, to achieve effective separation of copper and arsenic, the above method requires additional physical activation steps such as mechanical ball milling and ultrasonication to strengthen the intermediate slag, which makes the process complex, significantly increases equipment investment and operating energy consumption, and requires high operational control. Summary of the Invention

[0006] To address the shortcomings of existing technologies, which employ simple processes leading to resource waste and arsenic recycling, and the difficulty in simultaneously achieving economic efficiency and operability by shifting to complex processes for resource recovery, this invention provides a method for enriching copper from waste acid solutions in copper smelting. This method offers a novel approach to waste acid treatment that achieves a simple process, easy control, high resource recovery rate, and effective removal of arsenic from the system.

[0007] To achieve this objective, the following solution is provided: This invention provides a method for enriching copper from copper smelting waste acid solution, comprising the following steps: S1. Add a sulfiding agent to the raw acid solution of copper smelting waste to carry out a sulfidation reaction. After stirring, the solution is naturally separated by sedimentation to obtain arsenic slag slurry and sulfidated liquid. S2. The arsenic slag slurry is mixed with a new batch of copper smelting waste acid raw liquid for a cyclic reaction to achieve the enrichment of copper in the arsenic slag of the arsenic slag slurry; the sedimentation separation and replenishment of new raw liquid are repeated until the copper content in the arsenic slag reaches the predetermined value to obtain copper-rich arsenic slag slurry. S3. Collect the sulfided liquid separated by sedimentation during the cycle reaction in step S2, combine it with the sulfided liquid in step S1, add sulfiding agent to carry out deep sulfidation reaction, and then separate the solid and liquid after the reaction to obtain low copper and arsenic slag. S4. The copper-rich arsenic slag slurry from step S2 is subjected to solid-liquid separation to obtain copper-rich arsenic slag, which is then returned to the copper smelting pyrometallurgical system to achieve copper resource recovery.

[0008] Furthermore, in steps S1 and S3, the vulcanizing agent is a sodium hydrosulfide solution with a mass fraction of 15-25%.

[0009] Further, in step S1, the amount of sulfurizing agent added is controlled so that the molar ratio of sulfur to arsenic in the waste acid stock solution is (1.0-2.0):1; the reaction is carried out at 20-30 °C for 0.5-1.5 h.

[0010] Furthermore, in step S2, the cyclic reaction is achieved by controlling the molar ratio of arsenic in the arsenic slag slurry to copper in the new batch of copper smelting waste acid solution to (20-40):1.

[0011] Furthermore, in step S2, the cyclic reaction is carried out at 20-30 °C, and the single reaction time is 1-2 h.

[0012] Furthermore, in step S2, the predetermined value is that the mass percentage content of copper in the arsenic slag reaches 30-36%.

[0013] Further, in step S3, the amount of sulfurizing agent added is controlled so that the molar ratio of sulfur to arsenic in the waste acid stock solution is (2.0-3.0):1; the reaction is carried out at 20-30 °C for 1-2 h.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention achieves efficient copper enrichment simply by recycling arsenic slag slurry and adjusting the reactant ratio (As / Cu) over a wide range. This greatly shortens the process flow. The core equipment only requires conventional reaction tanks and separation equipment, without the need for expensive activation devices and precision metering and control systems, thus significantly reducing equipment investment, maintenance costs, and process energy consumption.

[0015] 2. The entire process of this invention is carried out at room temperature, eliminating the need for heating (e.g., 40-80°C) or maintaining a specific gas atmosphere (e.g., SO2 protection) as required by some existing technologies. This not only further reduces energy consumption but also simplifies operation and control, improves the stability and safety of the production process, and makes it easier to promote and apply industrially.

[0016] 3. This invention drives the reaction through process design rather than precise control, which greatly reduces the requirements for operational precision and simplifies equipment configuration. Its core lies in controlling the high molar ratio of arsenic (As) in arsenic slag to copper (Cu) in waste acid. This high ratio design means that the sulfur source in the system is always in excess, which greatly reduces the precision requirements for the amount of fresh sulfiding agent (such as NaHS) added to the process. This avoids the control problems and operational instability risks caused by the need for precise control of the amount of sulfiding agent in existing sulfidation methods.

[0017] 4. This invention overturns the traditional approach of "prioritizing the complete separation of copper and arsenic," instead selectively fixing copper in the arsenic slag matrix through "cyclic enrichment," ultimately producing copper-rich arsenic slag with a copper grade as high as 30-36%. This product can be directly returned to the copper smelting pyrometallurgical system as a high-quality raw material, achieving high-value copper recovery. At the same time, the low-copper-arsenic slag produced by the deep sulfidation step achieves the concentration and solidification of arsenic, which can be removed from the smelting water system through safe landfill and other methods. Furthermore, this invention not only treats waste acid but also converts the valuable metallic copper in it into secondary raw materials (copper-rich arsenic slag) that can be directly reused in the main process, while converting the harmful element arsenic into low-copper-arsenic slag that is easy to manage in the environment, forming a closed-loop resource utilization model of "treating waste with waste," which also has good environmental and economic benefits. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of the method for enriching copper from copper smelting waste acid solution according to the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to preferred embodiments. The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values. These ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed herein.

[0020] Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0021] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0022] Example 1 like Figure 1 As shown in the process flow diagram, this embodiment provides a method for enriching copper from copper smelting waste acid solution, including the following steps: S1. Take 400 mL of copper smelting waste acid raw liquid and pump it into sulfidation reaction tank B. The copper smelting waste acid raw liquid contains Cu 76.1 mg / L, As 1829.5 mg / L and sulfuric acid 160.5 g / L. Under mechanical stirring at 25℃, slowly add 20% sodium hydrosulfide solution to carry out sulfidation reaction, so that the molar ratio of the total amount of sulfur added to the total amount of arsenic in the waste acid raw liquid (S / As) is (1.4-1.6):1. After stirring continuously for 1 h, transfer the mixture to a settling tank and let it stand for natural sedimentation separation to obtain the upper layer of clear sulfided liquid (supernatant) and the lower layer of concentrated arsenic slag slurry. S2. Return the bottom arsenic slag slurry to sulfidation reaction tank A, add 320 mL of a new batch of copper smelting waste acid stock solution, and control the molar ratio of the total amount of arsenic in the arsenic slag slurry to the total amount of copper in the newly added waste acid stock solution to be (25-30):1. After mixing, stir at 25℃ for 1.5 h for circulation reaction, carry out sedimentation separation, and obtain supernatant and new concentrated arsenic slag slurry, thereby achieving the enrichment of copper in the arsenic slag of the arsenic slag slurry; collect the supernatant, use the arsenic slag slurry for the next round of circulation, and repeat the sedimentation separation and replenishment of new stock solution operation until the 12th round of circulation, when the copper content in the arsenic slag in the arsenic slag slurry reaches 33.2%, and copper-rich arsenic slag slurry is obtained. S3. Combine the sulfided liquid separated by sedimentation during the cyclic reaction in step S2 with the sulfided liquid described in step S1, return it to the sulfidation reaction tank B, add an excess sodium hydrosulfide solution with a mass fraction of 20%, and control the molar ratio of the total amount of sulfur added to the total amount of arsenic in the sulfided liquid to be (2.3-2.6):1, carry out a deep sulfidation reaction, react at 25°C for 1.5 h, and then filter under pressure to separate the solid and liquid, and obtain low copper and arsenic slag. S4. The copper-rich arsenic slag slurry is filtered by pressure to separate the solid and liquid components, and then returned to the copper smelting pyrometallurgical system to achieve copper resource recovery.

[0023] In this embodiment, all sulfidation reactions are carried out in a reactor equipped with a sealed gas collection hood. The trace amounts of hydrogen sulfide (H2S) gas generated are introduced into a spray tower with a mass fraction of 10% sodium hydroxide solution for absorption and treatment, ensuring that the exhaust gas meets emission standards. The low-copper-arsenic slag generated in step S3 will be transported to a qualified hazardous waste safe landfill for final disposal.

[0024] After 12 rounds of cyclic enrichment, the final copper-rich arsenic slag obtained by pressure filtration has a copper content of 33.2% by mass, an arsenic content of 11.7%, and a sulfur content of 28.5%, successfully achieving efficient and selective enrichment of copper in arsenic slag. The product can be directly used as a raw material for copper smelting. The low-copper-arsenic slag produced after deep sulfidation has an arsenic content enriched to 54.7%, while the copper content is reduced to 0.85%, effectively achieving deep separation of arsenic and copper. The product has a stable morphology and is suitable for safe disposal.

[0025] Example 2 This embodiment provides a method for enriching copper from copper smelting waste acid solution, including the following steps: S1. Take 400 mL of copper smelting waste acid raw liquid and pump it into sulfidation reaction tank B. The copper smelting waste acid raw liquid contains Cu 76.1 mg / L, As 1829.5 mg / L, and sulfuric acid 160.5 g / L. Under mechanical stirring at 20℃, slowly add a 25% sodium hydrosulfide solution to carry out the sulfidation reaction. Control the amount of sodium hydrosulfide solution added so that the molar ratio (S / As) of the total amount of sulfur added to the total amount of arsenic in the waste acid raw liquid is (1.0-1.3):1. After stirring continuously for 1.5 h, transfer the mixture to a settling tank and let it stand for natural sedimentation separation to obtain the upper layer of clarified sulfidated liquid (supernatant) and the lower layer of concentrated arsenic slag slurry. S2. Return the bottom arsenic slag slurry to the sulfidation reaction tank A, add a new batch of copper smelting waste acid stock solution, and control the molar ratio of the total amount of arsenic in the arsenic slag slurry to the total amount of copper in the newly added waste acid stock solution to be (35-40):1. After mixing, stir at 20℃ for 1 h for circulation reaction, carry out sedimentation separation, and obtain supernatant and new concentrated arsenic slag slurry, thereby achieving the enrichment of copper in the arsenic slag of the arsenic slag slurry; collect the supernatant, use the arsenic slag slurry for the next round of circulation, and repeat the sedimentation separation and replenishment of new stock solution operation until the 12th round of circulation, when the copper content in the arsenic slag in the arsenic slag slurry reaches 36.0%, and copper-rich arsenic slag slurry is obtained. S3. Combine the sulfided liquid separated by sedimentation during the cycle reaction in step S2 with the sulfided liquid described in step S1, return it to the sulfidation reaction tank B, add an excess sodium hydrosulfide solution with a mass fraction of 25%, control the molar ratio of the total amount of sulfur added to the total amount of arsenic in the sulfided liquid to be (2.8-3.0):1, carry out a deep sulfidation reaction, react at 20°C for 1 h, and then filter under pressure to separate the solid and liquid, and obtain low copper and arsenic slag. S4. The copper-rich arsenic slag slurry is filtered by pressure to separate the solid and liquid components, and then returned to the copper smelting pyrometallurgical system to achieve copper resource recovery.

[0026] In this embodiment, all sulfidation reactions are carried out in a reactor equipped with a sealed gas collection hood. The trace amounts of hydrogen sulfide (H2S) gas generated are introduced into a spray tower with a mass fraction of 10% sodium hydroxide solution for absorption and treatment, ensuring that the exhaust gas meets emission standards. The low-copper-arsenic slag generated in step S3 will be transported to a qualified hazardous waste safe landfill for final disposal.

[0027] After 12 rounds of cyclic enrichment, the final copper- and arsenic-rich slag obtained by pressure filtration has a metal content of 36.0% copper, 10.3% arsenic, and 28.7% sulfur by mass percentage. This successfully achieves efficient and selective enrichment of copper in arsenic slag, and the product can be directly used as a raw material for copper smelting. The low-copper- and arsenic-rich slag produced after deep sulfidation has an arsenic content enriched to 54.5%, while the copper content is reduced to 0.80%, effectively achieving deep separation of arsenic and copper. This product has a stable morphology and is suitable for safe disposal.

[0028] Example 3 This embodiment provides a method for enriching copper from copper smelting waste acid solution, including the following steps: S1. Take 400 mL of copper smelting waste acid raw liquid and pump it into sulfidation reaction tank B. The copper smelting waste acid raw liquid contains Cu 76.1 mg / L, As 1829.5 mg / L and sulfuric acid 160.5 g / L. Under mechanical stirring at 30℃, slowly add 15% sodium hydrosulfide solution to carry out sulfidation reaction. Control the amount of sodium hydrosulfide solution added so that the molar ratio (S / As) of the total amount of sulfur added to the total amount of arsenic in the waste acid raw liquid is (1.8-2.0):1. After stirring continuously for 0.5 h, transfer the mixture to a settling tank and let it stand for natural sedimentation separation to obtain the upper layer of clear sulfided liquid (supernatant) and the lower layer of concentrated arsenic slag slurry. S2. Return the bottom arsenic slag slurry to the sulfidation reaction tank A, add a new batch of copper smelting waste acid stock solution, and control the molar ratio of the total amount of arsenic in the arsenic slag slurry to the total amount of copper in the newly added waste acid stock solution to be (20-25):1. After mixing, stir at 30℃ for 1 h for circulation reaction, carry out sedimentation separation, and obtain supernatant and new concentrated arsenic slag slurry, thereby achieving the enrichment of copper in the arsenic slag of the arsenic slag slurry; collect the supernatant, use the arsenic slag slurry for the next round of circulation, and repeat the sedimentation separation and replenishment of new stock solution operation until the 15th round of circulation, when the copper content in the arsenic slag in the arsenic slag slurry reaches 30.1%, and copper-rich arsenic slag slurry is obtained. S3. Combine the sulfided liquid separated by sedimentation during the cyclic reaction in step S2 with the sulfided liquid described in step S1, return it to the sulfidation reaction tank B, add an excess sodium hydrosulfide solution with a mass fraction of 15%, and control the molar ratio of the total amount of sulfur added to the total amount of arsenic in the sulfided liquid to be (2.0-2.2):1, carry out a deep sulfidation reaction, react at 30°C for 1 h, and then filter under pressure to separate the solid and liquid, and obtain low copper and arsenic slag. S4. The copper-rich arsenic slag slurry is filtered by pressure to separate the solid and liquid components, and then returned to the copper smelting pyrometallurgical system to achieve copper resource recovery.

[0029] In this embodiment, all sulfidation reactions are carried out in a reactor equipped with a sealed gas collection hood. The trace amounts of hydrogen sulfide (H2S) gas generated are introduced into a spray tower with a mass fraction of 10% sodium hydroxide solution for absorption and treatment, ensuring that the exhaust gas meets emission standards. The low-copper-arsenic slag generated in step S3 will be transported to a qualified hazardous waste safe landfill for final disposal.

[0030] After 15 rounds of cyclic enrichment, the final copper-rich arsenic slag obtained by pressure filtration has a metal content of 30.1% copper, 13.2% arsenic, and 28.9% sulfur by mass percentage. This successfully achieves efficient and selective enrichment of copper in arsenic slag, and the product can be directly used as a raw material for copper smelting. The low-copper-arsenic slag produced after deep sulfidation has an arsenic content enriched to 55.1%, while the copper content is reduced to 0.82%, effectively achieving deep separation of arsenic and copper. This product has a stable morphology and is suitable for safe disposal.

[0031] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for enriching copper from copper smelting waste acid solution, characterized in that, Includes the following steps: S1. Add a sulfiding agent to the raw acid solution of copper smelting waste to carry out a sulfidation reaction. After stirring, the solution is naturally separated by sedimentation to obtain arsenic slag slurry and sulfidated liquid. S2. The arsenic slag slurry is mixed with a new batch of copper smelting waste acid raw liquid for a cyclic reaction to achieve the enrichment of copper in the arsenic slag of the arsenic slag slurry; the sedimentation separation and replenishment of new raw liquid are repeated until the copper content in the arsenic slag reaches the predetermined value to obtain copper-rich arsenic slag slurry. S3. Collect the sulfided liquid separated by sedimentation during the cycle reaction in step S2, combine it with the sulfided liquid in step S1, add sulfiding agent to carry out deep sulfidation reaction, and then separate the solid and liquid after the reaction to obtain low copper and arsenic slag. S4. The copper-rich arsenic slag slurry from step S2 is subjected to solid-liquid separation to obtain copper-rich arsenic slag, which is then returned to the copper smelting pyrometallurgical system to achieve copper resource recovery.

2. The method for enriching copper from copper smelting waste acid solution according to claim 1, characterized in that, In steps S1 and S3, the vulcanizing agent is a sodium hydrosulfide solution with a mass fraction of 15-25%.

3. The method for enriching copper from copper smelting waste acid solution according to claim 1, characterized in that, In step S1, the amount of sulfurizing agent added is controlled so that the molar ratio of sulfur to arsenic in the waste acid stock solution is (1.0-2.0):1; the reaction is carried out at 20-30℃ for 0.5-1.5 h.

4. The method for enriching copper from copper smelting waste acid solution according to claim 1, characterized in that, In step S2, the cyclic reaction is achieved by controlling the molar ratio of arsenic in the arsenic slag slurry to copper in the new batch of copper smelting waste acid solution to (20-40):

1.

5. The method for enriching copper from copper smelting waste acid solution according to claim 1, characterized in that, In step S2, the cyclic reaction is carried out at 20-30°C, and the single reaction time is 1-2 h.

6. The method for enriching copper from copper smelting waste acid solution according to claim 1, characterized in that, In step S2, the predetermined value is that the mass percentage of copper in the arsenic slag reaches 30-36%.

7. The method for enriching copper from copper smelting waste acid solution according to claim 1, characterized in that, In step S3, the amount of sulfurizing agent added is controlled so that the molar ratio of sulfur to arsenic in the waste acid stock solution is (2.0-3.0):1; the reaction is carried out at 20-30℃ for 1-2 h.

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