Method for comprehensively recovering valuable elements from nonferrous smelting waste acid

Abstract

The invention relates to a method for comprehensively recovering valuable elements from nonferrous smelting waste acid, and belongs to the technical field of metallurgical engineering. The method comprises the following steps: S1, pumping the waste acid into a first-stage reactor with the dissolved oxygen concentration controlled to be 2 mg / L or below, and adding zero-valent iron powder and pyrrhotite to carry out a reduction reaction, so that pentavalent arsenic in the waste acid is reduced into trivalent arsenic; after the reaction, carrying out solid-liquid separation to obtain copper sulfide slag and reduced liquid containing trivalent arsenic; s2, transferring the reduced liquid obtained in the step S1 to a second-stage reactor with an aeration or ventilation function, and blowing air, oxygen-enriched air or oxygen into the reduced liquid to carry out oxidation reaction, so that trivalent arsenic is oxidized and forms iron arsenate precipitate with iron ions; and after the reaction, carrying out solid-liquid separation to obtain iron arsenate slag and oxidized liquid. According to the method, high-selectivity and high-efficiency separation of copper and arsenic is realized through a valence oscillation strategy of first reduction and then oxidation. The average copper recovery rate is 98% or above, and the average arsenic removal rate is 99% or above.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgical engineering, and particularly relates to a method for comprehensively recovering valuable elements from non-ferrous smelting waste acid. BACKGROUND

[0002] A large amount of SO2 flue gas generated in the process of non-ferrous metal smelting such as lead-zinc and copper is generally used for sulfuric acid production. Since the flue gas also contains heavy metal dust such as mercury, the flue gas for acid production often needs to be washed and impurities removed through a purification process. A large amount of high-concentration acid heavy metal wastewater, referred to as waste acid, is generated in the process of washing and dedusting. The waste acid has high acidity, contains various heavy metal ions, and has high heavy metal ion concentration, complex form and high toxicity, and thus cannot be directly recycled and utilized in production. The traditional treatment of waste acid mainly adopts lime neutralization and precipitation treatment. However, the method produces a large amount of calcium sulfate sludge, and the sludge contains copper and arsenic and is classified as hazardous waste, which leads to high treatment and management costs of enterprises. Therefore, low-cost and environmentally friendly treatment of waste acid has become a technical difficulty to be solved in the current non-ferrous industry.

[0003] A method for comprehensively recovering valuable elements from non-ferrous smelting waste acid is disclosed in CN120624826A. The method comprises the following steps: S1, mixing the waste acid with pyrrhotite and reacting under a sulfur dioxide atmosphere, and then obtaining copper slag and copper-depleted liquid through solid-liquid separation after the reaction; S2, introducing H2S gas into the copper-depleted liquid obtained in step S1, and then obtaining arsenic sulfide slag and arsenic-depleted liquid through solid-liquid separation after the reaction. The FeS in the pyrrhotite selectively reacts with CuSO4 in the waste acid to form insoluble copper sulfide precipitate. At the same time, under the protection of the sulfur dioxide atmosphere, the arsenic element in the waste acid remains in a dissolved state and does not precipitate. The synergistic effect of the two can effectively separate the copper and arsenic elements in the waste acid, and the separation steps are simple and efficient. The scheme is highly dependent on the continuous introduction of two dangerous gases (SO2 and H2S) throughout the process, which leads to the following inherent defects: 1. High safety risk: SO2 and H2S are both toxic and harmful gases. The entire system has a high risk of leakage, which seriously threatens the health of operating personnel and production safety, and requires extremely strict sealing and safety protection measures for equipment.

[0004] 2. High operating cost: SO2 is continuously consumed as a “protective gas” and H2S is continuously consumed as a precipitant. The preparation, storage and transportation of these two gases are costly.

[0005] 3. Process complexity and control difficulty: This process has strict requirements for the rate of SO2 input and system sealing. If the input is insufficient, it cannot effectively reduce pentavalent arsenic and inhibit premature precipitation of arsenic; if the input is excessive, it will lead to the generation of SO2 tail gas, forming a new waste gas treatment problem. This makes the control of the process flow complex and unstable.

[0006] 4. Equipment corrosion problem: In a high-temperature acidic environment, high concentrations of SO2 and H2S can accelerate equipment corrosion, which significantly increases equipment investment and maintenance costs.

[0007] In summary, this scheme uses two dangerous gases as the cornerstone of the process, although it achieves copper-arsenic separation, but at the cost of poor safety, high cost, complex control and high environmental risk, which greatly limits its industrial application prospects. SUMMARY

[0009] To solve or partially solve the problems in the related art, the present application provides a method for comprehensively recovering valuable elements from non-ferrous smelting contaminated acid, which can efficiently separate and recover arsenic and copper from the source, while eliminating the major safety risks brought by SO2 and H2S.

[0010] The method for comprehensively recovering valuable elements from non-ferrous smelting contaminated acid in the present application comprises the following steps: S1: Pumping the contaminated acid into a first reactor with a dissolved oxygen concentration controlled below 2 mg / L, adding zero-valent iron powder and pyrite for reduction reaction, so that pentavalent arsenic in the contaminated acid is reduced to trivalent arsenic; after the reaction, solid-liquid separation is performed to obtain copper sulfide slag and reduced liquid containing trivalent arsenic; S2: Transferring the reduced liquid obtained in S1 to a second reactor with aeration or ventilation function, and blowing air, oxygen-enriched air or oxygen into the reduced liquid for oxidation reaction, so that trivalent arsenic is oxidized and forms ferric arsenate precipitate with iron ions; after the reaction, solid-liquid separation is performed to obtain ferric arsenate slag and oxidized liquid.

[0011] Further, the reaction temperature of step S1 is 50-70℃, the reaction time is 1-3 hours, and the reaction is carried out under stirring conditions.

[0012] Further, the reaction temperature of step S2 is 60-80℃, and the aeration time is 2-4 hours.

[0013] Further, the particle size of the zero-valent iron powder in step S1 is 0.1-0.3mm.

[0014] Further, the particle size of the pyrite in step S1 is 200-400 mesh.

[0015] Further, the waste acid contains arsenic 0.5-18.5g / L, copper 1.2-4.1g / L, and pH value is 0.5-1.5.

[0016] Further, the waste acid contains arsenic 0.5-18.5g / L, copper 1.2-4.1g / L, and pH value is 0.5-1.5.

[0017] Further, the waste acid contains arsenic 0.5-18.5g / L, copper 1.2-4.1g / L, and pH value is 0.5-1.5.

[0018] Further, the waste acid contains arsenic 0.5-18.5g / L, copper 1.2-4.1g / L, and pH value is 0.5-1.5.

[0019] The mechanism of action of the present application is: The traditional way of dealing with waste acid containing arsenic and copper is usually trapped in a fixed mode of thinking: either oxidize to the end or reduce to the end.

[0020] If oxidized all the way: pentavalent arsenic (As(V)) will immediately generate ferric arsenate precipitate with iron ions in the solution, which will wrap and carry a large amount of copper, resulting in copper and arsenic mixed and unable to separate.

[0021] If reduced all the way: trivalent arsenic (As(III)) has higher solubility, but it is difficult to be stably solidified subsequently, and the reduction environment may also cause copper to be difficult to precipitate or form other complex products. In the technical solution of the present application, the core strategy for efficient and selective separation of copper and arsenic is to create the best separation conditions first, and then create the best fixation conditions.

[0022] First step: reduction stage —— create a window for "copper-arsenic separation" In an anaerobic environment, zero-valent iron (Fe 0 ) is added to the acidic waste acid to make arsenic "invisible" and make copper precipitate first. The chemical reactions that occur are as follows: Fe 0 + 2H + → Fe 2+ + H2↑ H3AsO4(As(V)) + 2Fe 2+ + 2H + → H3AsO3(As(III)) + 2Fe 3+ + H2O S 2 + Cu 2+ →CuS↓ That is, through the dissolution of iron, strong reducing ferrous ions and nascent hydrogen gas are produced; then in acidic and Fe... 2+ Under the influence of the pyrrhotite, As(V) is reduced to As(III). As(III) has a much higher solubility in acidic solutions than As(V). It does not form stable precipitates with iron ions, thus remaining stably in solution. Simultaneously, the added pyrrhotite releases sulfur... 2- It will preferentially react with Cu in the solution. 2+ The reaction produces a very insoluble copper sulfide (CuS) precipitate. Because arsenic is in a soluble state, it will not mix into the copper slag. By solid-liquid separation, pure copper sulfide slag and a solution rich in soluble As(III) can be obtained.

[0023] Step Two: Oxidation Stage – Creating Conditions for Arsenic Stabilization Air, oxygen-enriched air, or oxygen is bubbled into the As(III)-containing solution in the next step. The chemical reaction that occurs is as follows: 4Fe 2+ + O2 + 4H + → 4Fe 3+ + 2H2O H3AsO3(As(III)) + 2Fe 3+ + H2O → H3AsO4(As(V)) + 2Fe 2+ + 2H + Fe 3+ + H2AsO4 - →FeAsO4(s) + 2H + Fe 3+ +3H₂O→Fe(OH)₃(s) The Fe produced in the previous step is removed by blowing in air, oxygen-enriched air, or oxygen. 2+ Oxidized to Fe 3+ Oxygen directly oxidizes As(III) very slowly, but it oxidizes Fe. 2+ The speed is extremely fast. The newly generated Fe... 3+ It immediately oxidizes As(III), while itself is reduced back to Fe. 2+ And this Fe 2+ It was immediately oxidized to Fe by O2 in the air. 3+ The process continues to oxidize the next As(III). This cycle repeats, and As(III) is efficiently re-oxidized to As(V). The generated As(V) then reacts with the large amount of Fe in the solution. 3+These combine to form ferric arsenate precipitate. Meanwhile, in solutions containing a large amount of iron ions, the removal of As(V) is not merely the formation of independent FeAsO4, but also... 3+ Hydrolysis generates amorphous ferric hydroxide flocs, which allow As(V) to be adsorbed and co-precipitated, thus making the removal of arsenic in this application more thorough.

[0024] The technical solution of this application actively transforms the pollutant from an easily treatable form (As(V)) into a recognized "more difficult to treat" form (As(III)), and then utilizes the unique properties of this form (high solubility) to achieve intermediate separation. The above process is not a simple combination of two independent steps; the product of the first step (Fe...) 2+ And As(III)) are necessary raw materials for the second step reaction. The entire process consists of one reactant (Fe) 0 The consumption of Fe naturally transitions to the next stage (the introduction of O2), forming a self-driven, time-sequential cascade reaction system. In the above process, inexpensive zero-valent iron is used as a key technological means, playing the roles of: reducing agent (Fe... 0 ), reaction medium (Fe 2+ / Fe 3+ ) and the precipitated framework (Fe) 3+ ), eventually forming a stable solidified body.

[0025] The beneficial effects of this application are: 1. Significantly improved safety: This application completely eliminates the use of dangerous gases such as SO2 and H2S that are necessary in the prior art, thus eliminating the major safety risks brought by SO2 and H2S from the source. The entire process only uses iron powder, air, oxygen-enriched air or oxygen, and the operating environment is safe and friendly.

[0026] 2. This application achieves highly selective and efficient separation of copper and arsenic through a "reduction-oxidation" valence state oscillation strategy. This application is environmentally friendly with a low risk of secondary pollution: no toxic or harmful gases are emitted throughout the entire process. Copper is recovered as high-grade copper sulfide slag, which can be directly used as a smelting raw material, with an average copper recovery rate of over 98%. Arsenic is stably solidified in ferric arsenate, facilitating safe disposal or resource utilization as a by-product, with an average arsenic removal rate of over 99%.

[0027] 3. This application uses inexpensive and readily available solid reagents such as zero-valent iron powder and pyrrhotite to replace expensive and difficult-to-store and transport hazardous gases, significantly reducing raw material costs. Simultaneously, it utilizes the Fe produced naturally during the reaction from zero-valent iron. 2+ The subsequent introduction of air, oxygen-enriched air, or oxygen enables low-cost, rapid oxidation of As(III) without the need for additional expensive oxidants, resulting in extremely low operating costs. The entire process described in this application is concise, simple to operate, and easily scalable for stable industrial-scale operation. Attached Figure Description

[0028] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments thereof.

[0029] Figure 1 This is a schematic diagram of the process flow in this application. Detailed Implementation

[0030] The embodiments of this application will now be described in more detail with reference to the examples. While embodiments of this application are shown in the examples, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art. Example 1

[0031] The method for comprehensively recovering valuable elements from waste acid in non-ferrous smelting in this embodiment is applied to waste acid from a copper smelter, whose main components are: As 8.5 g / L (existing as H3AsO3, the same below), Cu 2.3 g / L (existing as Cu...). 2+ (Form exists, the same below), Fe 2+ 1.2 g / L, pH=1.0.

[0032] The processing steps are as follows, and the process flow is as follows: Figure 1 As shown: Step S1 (Reduction and Copper Plating): Take 1L of waste acid into a sealed first reactor, and purge with nitrogen to reduce the dissolved oxygen concentration to below 1.5 mg / L. Add 12.6 g of zero-valent iron powder with a particle size between 0.1-0.2 mm. Add 6.4 g of 300-mesh pyrrhotite (according to the Cu content in the waste acid). 2+ (Based on 1.5 times the molar amount). The reaction was carried out at 60°C and stirred at 200 rpm for 2 hours. After the reaction, solid-liquid separation was performed to obtain 5.18 g of copper sulfide slag (analyzed to contain 43.2% Cu and 0.35% As).

[0033] Step S2 (Oxidation and Arsenic Fixation): The reduced liquid obtained from S1 was transferred to a second reactor equipped with an aeration device. Air was bubbled in at 70°C at a rate of 2.2 L / min for 3 hours. After the reaction, solid-liquid separation was performed to obtain 30.2 g of ferric arsenate slag (analyzed to contain 28.1% As).

[0034] Step S3 (Deep Heavy Metal Removal Segment): Sodium sulfide was added to the oxidized solution obtained from S2 for heavy metal precipitation treatment to precipitate residual zinc, cadmium, and lead heavy metals. After solid-liquid separation, the heavy metal-free solution was obtained. Step S4: Perform defluorination and dechlorination on the liquid after heavy metal removal. The final purified liquid can be returned to the smelting system as a solution for washing flue gas. It should be noted that the removal of heavy metals and defluorination and dechlorination by adding sodium sulfide can be carried out using conventional techniques in the field, and will not be elaborated further here.

[0035] The final treatment results in this embodiment are: copper recovery rate of 97.4% and arsenic removal rate of 99.9%. Example 2

[0036] The method for comprehensively recovering valuable elements from waste acid from non-ferrous smelting in this embodiment is used to treat waste acid from a zinc smelter, whose main components are: As 15.2 g / L, Cu 1.5 g / L, Fe 2+ 2.5 g / L, pH=0.5. The treatment steps are as follows: Step S1: Add 1L of waste acid to a closed first reactor, controlling dissolved oxygen <1.0 mg / L. Add 28.3g of zero-valent iron powder with a particle size between 0.2-0.3mm. Add 5.1g of 400-mesh pyrrhotite (calculated as Cu). 2+ (Based on 1.8 times the molar amount). The reaction was stirred at 70°C for 1 hour. 4.8 g of copper sulfide slag was obtained (containing 30.6% Cu and 0.42% As).

[0037] Step S2: Oxygen was bubbled in at 80°C (rate 0.5 L / min), and the reaction was carried out for 2 hours. 41.5 g of ferric arsenate slag (containing 36.4% As) was obtained.

[0038] The final treatment results in this embodiment are: copper recovery rate of 98.0% and arsenic removal rate of 99.4%. Example 3

[0039] The method for comprehensively recovering valuable elements from waste acid in non-ferrous smelting in this embodiment is used to treat waste acid from a copper smelter, whose main components are: As 4.8 g / L, Cu 4.1 g / L, Fe 2+ 0.9 g / L, pH=1.5.

[0040] The processing steps are as follows: Step S1: Add 1 L of waste acid to a closed first reactor, controlling dissolved oxygen <2.0 mg / L. Add 9.84 g of zero-valent iron powder with a particle size between 0.1-0.3 mm. Add 9.5 g of 200-mesh pyrrhotite (calculated as Cu).2+ (Based on 1.2 times the molar amount). The reaction was stirred at 50°C for 3 hours. 10 g of copper sulfide slag was obtained (containing 39.9% Cu and 0.28% As).

[0041] Step S2: At 60°C, oxygen-enriched air (oxygen concentration 40%, rate 1.2 L / min) was bubbled in, and the reaction was carried out for 4 hours. 15.6 g of ferric arsenate slag (containing 30.7% As) was obtained.

[0042] The final treatment results in this embodiment are: copper recovery rate of 97.3% and arsenic removal rate of 99.8%. Example 4

[0043] The method for comprehensively recovering valuable elements from waste acid in non-ferrous smelting in this embodiment is used to treat waste acid from a lead-zinc smelter, whose main components are: As 18.5 g / L, Cu 3.8 g / L, Fe 2+ 4.2 g / L, pH=0.6.

[0044] Step S1: Add 1 L of waste acid to a closed first reactor, controlling dissolved oxygen <1.0 mg / L. Add 30.7 g of zero-valent iron powder with a particle size between 0.1-0.2 mm. Add 11.5 g of 350 mesh pyrrhotite (calculated as Cu). 2+ (Based on 1.6 times the molar amount). The reaction was stirred at 65°C for 1.5 hours. 10.5 g of copper sulfide slag was obtained (containing 35.8% Cu and 0.31% As).

[0045] Step S2: Air was bubbled in at 75°C (at a rate of 1.5 L / min) for 2.5 hours. 52.8 g of ferric arsenate slag (containing 34.8% As) was obtained.

[0046] The final treatment results in this embodiment are: copper recovery rate of 98.9% and arsenic removal rate of 99.3%. Example 5 (Single-tank batch scaling-up of copper smelting waste acid treatment)

[0047] The method for comprehensively recovering valuable elements from waste acid in copper smelting in this embodiment is used to treat waste acid from a copper smelter, with the following composition: As 12.5 g / L, Cu 1.2 g / L, Fe 2+ 3.2 g / L, pH=1.0; Processing capacity: 50 m³ of waste acid can be processed per batch. The processing steps are as follows: Step S1: Reduction reaction and copper precipitation Feeding and preparation: Pump 50 m³ of waste acid into a 50 m³ closed reaction tank.

[0048] Dissolved oxygen control scheme: The reaction tank is a fully enclosed structure, equipped with a mechanically sealed stirrer and a slightly positive pressure gauge. Before the reaction begins, high-purity nitrogen is introduced from the bottom of the tank for space displacement, with the flow rate adjusted to 45 Nm³ / h, for 20 minutes. During the reaction, a nitrogen protective atmosphere is maintained at a flow rate of 10 Nm³ / h to ensure a slightly positive pressure (0.5-1.0 kPa) inside the reactor. An online dissolved oxygen monitor is installed to monitor the dissolved oxygen concentration in the liquid phase in real time, ensuring DO < 2 mg / L.

[0049] Drug administration and reaction: Add zero-valent iron powder (particle size between 0.1-0.3mm): 1080 kg, purity above 95%.

[0050] Add pyrrhotite (300 mesh): 181 kg (calculated based on 1.6 times the molar amount of copper ions in the waste acid).

[0051] Reaction conditions: temperature 60±2℃, stirring power 30 kW, reaction time 3 hours. After liquid-solid separation, copper sulfide slag and reduced liquid were obtained. Copper sulfide slag yield: approximately 0.16 tons (containing 36.9% Cu and <0.3% As). Step S2: Oxidation reaction and arsenic fixation The reduced liquid is pumped into a reaction tank for oxidation. The tank is equipped with an aeration device at the bottom, through which compressed air is blown in at a rate of 100 Nm³ / h. The reaction temperature is controlled at 75℃, and the aeration time is 4 hours. Stirring is continuously maintained to ensure thorough mixing of the gas and liquid.

[0052] After the reaction is complete, the material is pumped into a plate and frame filter press for solid-liquid separation. Production of ferric arsenate slag: approximately 1.97 tons (containing 31.5% As).

[0053] Step S3 (Deep Heavy Metal Removal Segment): Sodium sulfide was added to the oxidized solution obtained from S2 for heavy metal precipitation treatment to precipitate residual zinc, cadmium, and lead heavy metals. After solid-liquid separation, the heavy metal-free solution was obtained. Step S4: Perform defluorination and dechlorination on the liquid after heavy metal removal. The final purified liquid can be returned to the smelting system as a solution for washing flue dust. It should be noted that the removal of heavy metals and defluorination and dechlorination by adding sodium sulfide can be carried out using conventional techniques in the field, such as lime milk precipitation for fluoride removal and copper slag for dechlorination, which will not be elaborated further here.

[0054] Treatment results: Copper recovery rate: 98.4%; Arsenic removal rate: 99.3%.

[0055] Based on the test results of Examples 1-5, it can be seen that the technical solution in this application has at least the following technical advantages: 1. Wide applicability of the technology: It has successfully treated waste acid from different smelting processes such as copper, zinc, and lead-zinc, with a wide range of arsenic concentrations (4.8-18.5 g / L), copper concentrations (1.2-4.1 g / L), and acidity (pH 0.5-1.3), proving the wide applicability of the method.

[0056] 2. Excellent and stable treatment results: In all cases, high-efficiency recovery of copper (recovery rate 97.3%-98.9%) and deep stabilization of arsenic (removal rate 99.3%-99.9%) were achieved, with excellent indicators and good repeatability.

[0057] 3. High degree of resource utilization: While removing pollutants, valuable elements are successfully recovered in the form of high-grade copper sulfide slag (Cu content 30.6%-43.2%) and stable ferric arsenate slag, achieving efficient enrichment and recovery of copper and arsenic.

[0058] 4. Demonstrated scalability: The process was successfully scaled up from a 1L pilot test (Examples 1-4) to a 50m³ scale (Example 5), with consistent treatment results, proving that the process has good engineering scale-up potential and industrial application prospects.

[0059] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for comprehensively recovering valuable elements from non-ferrous smelting waste acid, characterized in that, Includes the following steps: S1: Pump the waste acid into a first-stage reactor with dissolved oxygen concentration controlled below 2 mg / L, add zero-valent iron powder and pyrrhotite to carry out a reduction reaction, so that the pentavalent arsenic in the waste acid is reduced to trivalent arsenic; after the reaction, solid-liquid separation is carried out to obtain copper sulfide slag and reduced liquid containing trivalent arsenic. S2: The reduced liquid obtained from S1 is transferred to a second-stage reactor with aeration or ventilation function, and air, oxygen-enriched air or oxygen is blown into the reduced liquid to carry out an oxidation reaction, so that trivalent arsenic is oxidized and forms ferric arsenate precipitate with iron ions; after the reaction, solid-liquid separation is carried out to obtain ferric arsenate slag and oxidized liquid.

2. The method for comprehensively recovering valuable elements from non-ferrous smelting waste acid according to claim 1, characterized in that, The reaction temperature in step S1 is 50-70℃, the reaction time is 1-3 hours, and the reaction is carried out under stirring conditions.

3. The method for comprehensively recovering valuable elements from non-ferrous smelting waste acid according to claim 1, characterized in that, The reaction temperature in step S2 is 60-80℃, and the aeration time is 2-4 hours.

4. The method for comprehensively recovering valuable elements from non-ferrous smelting waste acid according to claim 1, characterized in that, The particle size of the zero-valent iron powder mentioned in step S1 is 0.1-0.3 mm.

5. The method for comprehensively recovering valuable elements from non-ferrous smelting waste acid according to claim 1, characterized in that, The pyrrhotite in step S1 has a particle size of 200-400 mesh.

6. The method for comprehensively recovering valuable elements from non-ferrous smelting waste acid according to claim 1, characterized in that, The waste acid contains arsenic 0.5-18.5 g / L, copper 1.2-4.1 g / L, and has a pH value of 0.5-1.

5.

7. The method for comprehensively recovering valuable elements from non-ferrous smelting waste acid according to claim 1, characterized in that, It also includes adding sodium sulfide to the oxidized liquid obtained from S2 for heavy metal precipitation treatment to precipitate residual zinc, cadmium, and lead heavy metals. After solid-liquid separation, a liquid after heavy metal removal is obtained. The liquid after heavy metal removal is then subjected to defluorination and chlorination. The final purified liquid can be returned to the smelting system as a solution for washing flue dust.

8. A method for comprehensively recovering valuable elements from non-ferrous smelting waste acid according to any one of claims 1 to 7, characterized in that, In step S1, zero-valent iron powder is added to make the ratio of the total number of moles of ferrous ions to the number of moles of pentavalent arsenic in the system reach 1.5:1 to 2.5:1; the total number of moles of ferrous ions in the system is the sum of the number of moles of ferrous ions contained in the waste acid itself and the number of moles of zero-valent iron powder added.

Images