Technological method for deeply removing copper from lead bullion by using dangerous solid waste

Abstract

The invention discloses a process method for deeply removing copper from crude lead by using dangerous solid wastes, and belongs to the technical field of non-ferrous metal metallurgy and resource utilization of the dangerous solid wastes. Dangerous solid waste containing arsenic and sulfur serves as a copper removal agent and is added into molten lead bullion, stirring and smelting are conducted at the temperature of 450-900 DEG C, copper reacts with arsenic and sulfur to generate cuprous sulfide, copper arsenide and other compounds insoluble in lead liquid by means of the preferential affinity of arsenic and sulfur to copper, the compounds float upwards to form a low-density arsenic matte scum layer, and efficient separation of copper is achieved through mechanical slag scattering. The copper content in the lead liquid after copper removal can be reduced to 0.1% or below, and meanwhile harmless treatment of dangerous solid waste and resource recycling of valuable elements are achieved. The method is simple in process, low in cost and high in copper removal efficiency, and has remarkable environmental benefits and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal smelting technology, and more particularly to a copper removal process for crude lead pyrometallurgical refining. Specifically, it is a method for deep copper removal from crude lead using hazardous solid waste containing arsenic and sulfur as a copper removal agent. This invention also belongs to the field of hazardous solid waste resource utilization technology, achieving the harmless disposal of hazardous waste and the synergistic recovery of valuable elements. Background Technology

[0002] In lead smelting, the crude lead produced by reduction smelting typically contains approximately 90% lead and 2.5%-5.0% copper and other impurities. The presence of copper severely affects the current efficiency, anode plate life, and cathode lead quality in subsequent lead electrolytic refining. Therefore, the copper content in the crude lead must be removed to below 0.1% before electrolysis.

[0003] Currently, industrial copper removal from crude lead mainly employs the melting and precipitation method and the sulfur removal method. The melting and precipitation method utilizes the principle that the solubility of copper in molten lead decreases with decreasing temperature, allowing copper to precipitate as a solid solution through slow cooling. This method is simple to operate, but its copper removal efficiency is limited, typically reducing the copper content to only 0.1%-0.2%, and it is quite sensitive to fluctuations in raw material composition. The sulfur removal method involves adding elemental sulfur to the molten lead, causing it to react with copper to form cuprous sulfide (Cu₂S) slag, which is insoluble in molten lead. Copper removal is achieved by removing the slag. This method achieves a good copper removal depth, but it has the following disadvantages: sulfur is expensive, increasing production costs; sulfur is volatile at high temperatures, creating a harsh working environment and causing material loss; excessive sulfur may react with lead to form lead sulfide (PbS), leading to lead loss.

[0004] The aforementioned traditional methods all require the consumption of commercial sulfur and other chemical raw materials, failing to integrate with the treatment of other industrial wastes, resulting in low resource utilization efficiency. Meanwhile, industries such as non-ferrous metal smelting, chemicals, and pesticides generate large quantities of hazardous solid waste containing arsenic and sulfur, such as arsenic sulfide slag produced from sulfide wastewater treatment. This type of waste has high arsenic content, strong toxicity, and unstable properties, making its safe disposal a serious challenge for the industry. Conventional landfill disposal not only occupies land resources but also poses a long-term risk of arsenic leaching and environmental pollution.

[0005] If these hazardous solid wastes containing arsenic and sulfur can be used as resources in the crude lead copper removal process, "waste treatment with waste" can be achieved, simultaneously solving the two major problems of high cost and difficult hazardous waste disposal in crude lead copper removal. However, existing technologies lack mature technical solutions that systematically utilize such specific hazardous wastes for deep copper removal from crude lead and elucidate its synergistic reaction mechanism and process conditions.

[0006] Therefore, developing a process that can co-process hazardous waste and achieve efficient and deep copper removal from crude lead has significant industrial application value and environmental protection significance. Summary of the Invention

[0007] The purpose of this invention is to overcome the technical defects of existing crude lead copper removal technology, such as strong dependence on commercial sulfur, high cost, and difficulty in disposing of hazardous solid waste containing arsenic and sulfur, and to provide an innovative, efficient, and environmentally friendly process for deep crude lead copper removal using hazardous solid waste.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A process for deep copper stripping of crude lead using hazardous solid waste, the process comprising the following steps: (1) Raw material preparation: Prepare molten crude lead with a lead content ≥90% and a copper content of 2.5%-5.0%; prepare copper removal agent, which is a hazardous solid waste containing arsenic and sulfur; (2) Smelting reaction: The calculated amount of copper stripping agent is added to the reactor containing the molten crude lead, and the mixture is stirred and smelted at a temperature of 450℃-900℃ to ensure that the copper stripping agent is evenly dispersed and fully reacts with the copper in the lead liquid. (3) Separation of scum: After the reaction is completed, stop stirring and let it stand to separate into layers. The copper-containing compounds generated by the reaction float to the surface to form an arsenic matte scum layer. Remove the upper scum layer to obtain the lead liquid after deep copper removal. Preferably, the copper removal agent is arsenic sulfide slag produced from sulfide wastewater treatment; Preferably, the arsenic sulfide slag contains 35.0%-45.0% arsenic and 40.0%-50.0% sulfur. Preferably, the copper removal agent can also be other solid wastes rich in arsenic and sulfur, as long as its arsenic content is not less than 1.0% and its sulfur content is not less than 5.0%, the copper removal effect of the present invention can be achieved. For example, arsenic-containing dust, smelting intermediate products containing sulfur and arsenic, etc. Preferably, the amount of copper stripping agent added in step (2) is theoretically calculated based on the copper content in crude lead and the effective content of arsenic and sulfur in the copper stripping agent, and the actual amount added is 1.0 to 1.5 times the theoretical requirement; The theoretical requirement refers to the minimum mass of sulfur and arsenic in the copper removal agent required to completely remove all copper from a given mass of crude lead, calculated based on the stoichiometric relationship of chemical reactions. Sulfur reacts preferentially with copper, and the remaining copper is removed by the reaction of arsenic.

[0009] The theoretical requirement for copper stripping agent is calculated as follows: a) Calculate the required sulfur (S) mass: Based on the reaction formula 2[Cu] + S = Cu2S, calculate the theoretical sulfur mass M required to remove all copper (Cu) from crude lead. S .

[0010] Calculation formula: MS 理论 =MCu×(M S / (2×M Cu ))=0.25MCu, where: MCu is the total mass of copper in crude lead, M S and M Cu These are the atomic weights of sulfur and copper, respectively.

[0011] b) Calculate the required mass of arsenic (As): Based on the reaction formula 3[Cu]+As=Cu3As, calculate the theoretical mass of arsenic MAs required to remove all copper (Cu) from crude lead.

[0012] Calculation formula: MAs 理论 =MCu×(M As / (3×M Cu ))0.40MCu, where M As This is the atomic weight of arsenic.

[0013] The specific calculation steps are as follows: a) Under the condition that the mass of copper stripping agent is constant, for example, if MS 实际 ≥MS 理论 : Sulfur is sufficient to remove all copper. The theoretical requirement is calculated based on sulfur demand, i.e., required copper removal agent mass = MS / (mass fraction of sulfur in the copper removal agent). Arsenic still participates in the reaction to some extent, but the theoretical calculation is based on sulfur. This method theoretically satisfies the copper removal needs of crude lead with any copper content, but when the sulfur content in the copper removal agent is low, it will result in a larger amount of copper removal agent added.

[0014] b) Under the condition that the mass of copper stripping agent is constant, if MS 实际 <MS 理论 : Sulfur will then be insufficient to remove all the copper. The sulfur will be depleted first, removing only a portion of the copper (corresponding to the amount of sulfur consumed, MS). 实际 However, this approach is particularly suitable for situations where the sulfur content in the copper stripping agent is low, or where the copper stripping agent simultaneously removes copper by both sulfur and arsenic, thus reducing the amount of copper stripping agent used (subsequent calculations will be based on this approach).

[0015] The arsenic requirement is calculated as follows (when sulfur is insufficient): Calculate the mass of copper removed by sulfur: MCu1 = MS 实际 ×(2×M Cu / M S ).

[0016] Calculate the remaining copper mass that needs to be removed by arsenic: MCu2 = MCu - MCu1.

[0017] Calculate the mass of arsenic required to remove residual copper: MAs1 = MCu2 × (M As / (3M Cu )).

[0018] Determine the theoretical demand: The theoretical required mass of copper stripping agent equals the minimum mass required to meet arsenic requirements, as follows: Max = (MS) 实际 / (mass fraction of sulfur in the copper stripping agent), MAs1 / (mass fraction of arsenic in the copper stripping agent)), but in actual operation, to ensure complete reaction, the copper stripping agent usually needs to provide both the calculated amount of arsenic MAs1 and the amount of sulfur it contains MS. 实际 Therefore, the theoretical demand should be based on the ability to simultaneously provide MAs1 and MS. 实际 The quality of the copper stripping agent. Because the same copper stripping agent may contain both sulfur and arsenic, the calculations are quite complex.

[0019] Simplified calculation method: Calculate the mass of copper stripping agent (MAs) required to completely remove all copper using arsenic. 实际 / (arsenic mass fraction in copper stripping agent)), and compared with sulfur-based (MS) 实际 By comparing the values ​​of / (sulfur mass fraction in copper stripping agent), the value that ensures a more sufficient supply of sulfur and arsenic is taken as the reference benchmark for calculating the theoretical demand. During implementation, the total amount of arsenic and sulfur required is calculated by stoichiometry, converted into the mass of copper stripping agent according to the composition of the copper stripping agent, and multiplied by a coefficient of 1.0-1.5 as the actual amount to be added.

[0020] In practical applications, the copper removal agent dosage calculated in b) can be used while taking into account the copper removal effect. Based on the actual indicators, the dosage of copper removal agent can be appropriately reduced to find the balance point between the best copper removal effect and the minimum amount of copper removal agent. This patent will not elaborate further.

[0021] Preferably, the reaction temperature in step (2) is 500℃-800℃, and the stirring time is controlled at 30-90 minutes.

[0022] The metallurgical mechanism of the process is as follows: The core of this invention lies in utilizing the extremely strong chemical affinity of arsenic (As) and sulfur (S) for copper (Cu). Thermodynamically, the Gibbs free energy change (ΔG) of the compounds formed by the reaction of arsenic and sulfur with copper is very negative, much lower than that of the compounds formed by their reaction with lead (Pb). Therefore, in a melt where lead and copper coexist, arsenic and sulfur will preferentially react with copper.

[0023] The sulfur (or sulfides) in the copper stripping agent reacts with copper dissolved in the lead solution to form cuprous sulfide (Cu₂S), which is extremely stable and insoluble in lead: 2[Cu] (inPb) +S (added) =Cu2S (s) The density of Cu₂S (~5.6 g / cm³) is much lower than that of molten lead (~11 g / cm³), causing it to float and separate. The arsenic in the copper stripping agent reacts with copper to form the stable intermetallic compound copper arsenide (Cu₃As). 3[Cu](inPb) +As (added) =Cu3As (s) Cu3As is also insoluble in lead and has a low melting point, making it easy to aggregate into a phase.

[0024] Under conditions where arsenic and sulfur coexist, more complex copper sulfide mineral phases (such as Cu) can be further formed. 12 As4S 13 These generated copper-containing compounds (Cu₂S, Cu₃As, and complex copper arsenide sulfides) collectively form a low-melting-point, low-density, and completely immiscible liquid phase with molten lead, namely arsenic matte. Because its density is much lower than that of molten lead, arsenic matte rapidly floats to the surface, forming a scum layer, thus achieving efficient copper capture and separation. Throughout the entire reaction process, the lead matrix hardly participates in the reaction, ensuring a high direct lead recovery rate.

[0025] The beneficial effects of this invention are as follows: Innovation and Resource Recycling: For the first time, it proposes using arsenic-containing sulfur-containing hazardous solid waste such as arsenic sulfide slag as a crude lead copper removal agent, realizing "waste treatment with waste" and transforming the disposal cost of hazardous waste into resource benefits, which is highly innovative.

[0026] High copper removal efficiency: Utilizing the synergistic copper removal effect of arsenic and sulfur, the removal capacity is superior to the traditional single sulfur method. It can remove 2.5%-5.0% copper from crude lead to a depth of less than 0.1%, which fully meets the feed requirements of electrolytic refining.

[0027] Significant cost reduction: Replacing expensive commercial sulfur with inexpensive or even negative disposal fees industrial hazardous waste significantly reduces the raw material cost of the copper removal process, resulting in obvious economic benefits.

[0028] Significant environmental benefits: By fixing toxic and harmful elements such as arsenic and sulfur in stable compounds (arsenic matte) produced in a closed metallurgical process, the harmless disposal and resource recovery are combined, fundamentally reducing environmental risks.

[0029] High process compatibility: This process can be directly integrated into the existing crude lead pyrometallurgical refining process without major modifications to the main smelting equipment. It is simple to operate and easy to promote and apply industrially. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited to the following embodiments. The theoretical calculations of the amount of copper stripping agent added in the embodiments are all based on the aforementioned method. Example

[0031] 500 kg of molten crude lead produced by reduction smelting was placed in a refining pot and its composition was determined to be: Pb 91.5% and Cu 3.8%. 21.48 kg of arsenic sulfide slag (composition: As 43.2% and S 46.1%) produced from the sulfidation wastewater treatment was weighed as copper stripping agent (approximately 1.25 times the theoretical required amount).

[0032] a) Calculate the required sulfur (S) mass: Based on the reaction formula 2[Cu]+S=Cu2S, calculate the theoretical sulfur mass MS required to remove all copper (Cu) from crude lead.

[0033] Calculation: MS = 500 × 3.8% × (32 / (2 × 64)) = 4.75 kg b) Calculate the required mass of arsenic (As): Based on the reaction formula 3[Cu]+As=Cu3As, calculate the theoretical mass of arsenic MAs required to remove all copper (Cu) from crude lead.

[0034] Calculation: MAs = 500 × 3.8% × (75 / (3 × 64)) = 7.42 kg c) The mass of copper stripping agent required to remove all copper entirely by relying on arsenic is 17.18 kg (7.42 / 43.2%). This is compared with the mass of copper stripping agent required based on sulfur, which is 10.30 kg (4.75 / 46.1%). The 17.18 kg that ensures a more sufficient supply of sulfur and arsenic is taken as the reference benchmark for calculating the theoretical requirement. With 1.25 times the theoretical requirement as the addition coefficient, the actual addition amount is 21.48 kg.

[0035] The copper stripping agent was added in batches to the molten lead, which was maintained at 550℃, while a mechanical stirrer was started at medium speed. After the addition was complete, stirring was continued for 60 minutes. Stirring was then stopped, and the mixture was allowed to stand for 20 minutes. A dark gray scum about 5 cm thick formed on the surface of the molten lead. The scum was completely removed using a scum remover. Analysis of the lead molten lead after copper stripping showed a Cu content of 0.08%. The copper stripping rate reached 97.9%. Example

[0036] 1000 kg of molten crude lead from reduction smelting was placed in a refining pot. Its composition was: Pb 90.2%, Cu 4.5%. Arsenic-containing dust (composition: As 25.3%, S 15.8%) was used as a copper stripping agent. According to calculations, 99.68 kg of this dust was added (approximately 1.4 times the theoretical amount).

[0037] a) Calculate the required sulfur (S) mass: Based on the reaction formula 2[Cu]+S=Cu2S, calculate the theoretical sulfur mass MS required to remove all copper (Cu) from crude lead.

[0038] Calculation: MS = 1000 × 4.5% × (32 / (2 × 64)) = 11.25 kg b) Calculate the required mass of arsenic (As): Based on the reaction formula 3[Cu]+As=Cu3As, calculate the theoretical mass of arsenic MAs required to remove all copper (Cu) from crude lead.

[0039] Calculate: MAs = 1000 × 4.5% × (75 / (3 × 64)) = 17.58 kg c) The mass of copper remover required to remove all copper entirely by relying on arsenic is 69.49 kg (17.58 / 25.3%). This is compared with the mass of copper remover required based on sulfur, which is 71.2 kg (11.25 / 15.8%). The 71.2 kg that ensures a more sufficient supply of sulfur and arsenic is taken as the reference benchmark for calculating the theoretical requirement. With 1.40 times the theoretical requirement as the addition coefficient, the actual addition amount is 99.68 kg.

[0040] The solution was vigorously stirred at 620℃ for 80 minutes, allowed to stand and separate into layers, and then the residue was sprinkled off. Analysis of the lead solution after copper removal showed that the copper content had dropped to 0.05%, and the copper removal rate reached 97.3%.

[0041] As can be seen from the embodiments, preferably, the copper removal agent is arsenic sulfide slag produced from sulfidation wastewater treatment, and the amount of copper removal agent used is small. Using the hazardous solid waste arsenic sulfide slag as a copper removal agent, this invention not only surpasses traditional methods in copper removal depth (copper content reduced to below 0.1%) and copper removal rate, but also fundamentally transforms the challenge of hazardous waste disposal into a beneficial additive in the production process, achieving a win-win situation for both environmental and economic benefits.

[0042] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A process for deep copper stripping of crude lead using hazardous solid waste, characterized in that... Includes the following steps: (1) Raw material preparation: Prepare molten crude lead with a lead content ≥90% and a copper content of 2.5%-5.0%; prepare copper removal agent, which is a hazardous solid waste containing arsenic and sulfur; (2) Smelting reaction: The copper removal agent is added to the molten crude lead and stirred and smelted at a temperature of 450℃-900℃, so that the arsenic and sulfur in the copper removal agent react with the copper in the crude lead; (3) Separation of scum: After the reaction is completed, stop stirring and let it stand to separate into layers. The copper-containing compounds generated by the reaction float to the surface to form an arsenic matte scum layer. Remove the upper scum layer to obtain lead liquid after deep copper removal.

2. The process for deep copper stripping of crude lead using hazardous solid waste according to claim 1, characterized in that: The copper removal agent is arsenic sulfide slag produced from sulfide wastewater treatment.

3. The process method for deep copper stripping of crude lead using hazardous solid waste according to claim 2, characterized in that: The arsenic sulfide slag contains 35.0%-45.0% arsenic and 40.0%-50.0% sulfur.

4. The process for deep copper stripping of crude lead using hazardous solid waste according to claim 1, characterized in that: The copper removal agent is a solid material with an arsenic content of ≥1.0% and a sulfur content of ≥5.0%.

5. The process method for deep copper stripping of crude lead using hazardous solid waste according to claim 1, characterized in that: The amount of copper stripping agent added in step (2) is 1.0-1.5 times the theoretical requirement. The theoretical requirement refers to the minimum mass of copper stripping agent required to completely remove all copper from a given mass of crude lead. It is calculated based on the effective sulfur and arsenic content in the copper stripping agent and the copper content in the crude lead, and follows the order in which sulfur reacts with copper in priority over arsenic.

6. The process method for deep copper stripping of crude lead using hazardous solid waste according to claim 1, characterized in that: The reaction temperature in step (2) is 500℃-800℃, and the stirring time is 30-90 minutes.

7. The process method for deep copper stripping of crude lead using hazardous solid waste according to claim 1, characterized in that: The copper-containing compound generated in step (2) includes at least one of cuprous sulfide, copper arsenide, or copper sulfarsenide.

8. The process method for deep copper stripping of crude lead using hazardous solid waste according to claim 1, characterized in that: The arsenic-copper matte slag mentioned in step (3) is used as a raw material for the extraction of copper and arsenic for resource recovery.