Method for deep impurity removal and high-quality resource utilization of smelting waste acid

Abstract

The application discloses a method for smelting deep impurity removal of waste acid and high-quality resource utilization, FeS is added to the waste acid for a first sulfuration reaction to generate As2S3 and HgS precipitates; iron mud is added to neutralize the pH to 2-4 to generate FeF3 precipitates; iron powder is added to generate Cu 2+ Pb, Zn and CdS precipitates; Bi2O3 is added to dissolve to generate Bi 3+ , F ‑ and Cl ‑ selectively to generate BiOCl and BiOF precipitates, and the total amount of the Bi2O3 precipitant is recovered and recycled; after the above reaction is separated by mud water, the As, Hg, Cu, Pb, Zn, Cd, F and Cl in the waste acid are removed in a direction and in a deep way; the elemental copper is used as raw material of a copper smelting plant, and the Zn and Pb rich sulfuration slag is used as raw material of a lead and zinc smelting plant; after the waste acid is deeply removed of impurities, the total iron and the sulfate radical in the waste acid are converted into FeSO4 and Fe2(SO4)3 by adding the iron-containing reagent, and after four steps of reaction including oxidation, hydrolysis, polymerization, ripening and post-treatment, the brownish liquid polymeric ferric sulfate reaches the qualified product standard.

Description

Technical Field

[0001] This invention belongs to the field of smelting wastewater treatment technology, specifically relating to a method for deep depurification and high-quality resource utilization of smelting waste acid. Background Technology

[0002] Sludge is a typical highly polluting wastewater generated in the metallurgical industry, with copper smelting producing approximately 20-50 m³ of it. 3 / t refined copper, lead smelting output is approximately 15~40 m 3 / t crude lead, zinc smelting output is approximately 10~30 m 3 Electrolytic zinc is characterized by high output, strong acidity, high salinity, high concentrations of heavy metals (As, Hg, Pb, Zn, Cu, Cd, etc.), fluorine, chlorine, etc., high toxicity, complex composition, and difficulty in treatment and resource utilization. Currently, waste acid treatment mainly includes neutralization precipitation, sulfide precipitation, lime-iron salt method, biological agent method, membrane separation method, ion exchange method, electrochemical method, adsorption method, evaporation concentration-fluorine and chlorine stripping method, or a combination of these methods. Treatment of waste acid using a single method typically fails to meet discharge standards or water quality requirements for industrial use. While combining multiple methods can meet discharge standards or water quality requirements, the process is lengthy, costly, and produces large amounts of slag, and it neglects the recovery and utilization of major valuable components (copper, lead, zinc, cadmium, sulfate, etc.) in the waste acid.

[0003] When organic wastewater from mineral processing and smelting is treated using the Fenton oxidation method to remove organic matter, Fe in the Fenton reaction... 2+ Oxidized to Fe 3+ The pH is then adjusted to 8-10 using NaOH, which reacts to form Fe(OH)3 precipitate (i.e., iron sludge). According to reports, iron sludge production accounts for approximately 1-5% (by mass) of the treated water volume; if the raw water has a high COD concentration, the iron sludge production can reach 5-10% of the treated water volume. Iron sludge is often classified as hazardous waste, and its treatment and disposal increase the burden on enterprises.

[0004] Currently, the challenges in the resource utilization of waste acid lie in the selective and deep removal of pollutants, the efficient and targeted separation and enrichment of valuable components, and high-quality resource utilization. Traditional methods are insufficient to address these challenges. Iron sludge, being hazardous waste, also requires finding high-quality resource utilization pathways to reduce disposal costs. Therefore, there is an urgent need for innovative thinking and technological approaches, using waste acid and iron sludge as primary raw materials, and employing iron sludge and relevant reagents to deeply remove impurities from the waste acid, thereby achieving high-quality resource utilization of both waste acid and iron sludge. Summary of the Invention

[0005] The purpose of this invention is to provide a method for deep purification and high-quality resource utilization of smelting waste acid.

[0006] The objective of this invention is achieved as follows: the method for deep deimpurification and high-quality resource utilization of smelting waste acid includes a first-stage sulfidation precipitation, neutralization precipitation, displacement reaction, a second-stage sulfidation precipitation, a two-step precipitation, and oxidative hydrolysis polymerization steps, specifically including: A. First-stage sulfide precipitation: FeS is added to the waste acid to carry out a first-stage sulfide reaction, resulting in first-stage sulfide precipitation liquid a and precipitate b. Precipitate b is treated as hazardous waste. B. Neutralization and precipitation: 1) After washing the iron mud with pure water and pressing and filtering, the resulting filter cake is crushed, dried and ground to obtain the prepared iron mud; 2) The prepared iron sludge is added to the first-stage sulfidation precipitation liquid a to carry out a neutralization reaction to obtain neutralized precipitation liquid c and precipitate d. Precipitate d is treated as hazardous waste. C. Displacement reaction: Iron powder is added to the neutralized and precipitated liquid c to carry out a displacement reaction, resulting in a displacement liquid e and elemental copper precipitate f. After removing impurities and drying, elemental copper precipitate f is used to obtain copper powder. D. Two-stage sulfidation precipitation: FeS and H2SO4 are added to the replacement liquid e to carry out a two-stage sulfidation reaction, resulting in a two-stage sulfidation precipitation liquid g and sulfide precipitate h. Sulfide precipitate h can be used as a raw material for lead-zinc smelters. E. Two-step precipitation: A certain amount of Bi2O3 is added to the two-stage sulfidation precipitation solution g to carry out the first precipitation reaction; then an appropriate amount of Bi2O3 is added to carry out the second precipitation reaction, obtaining the precipitation solution i and precipitate j; precipitate j is regenerated with NaOH solution to obtain Bi2O3 precipitant; Bi2O3 remains in the precipitation solution i. 3+ It reacts with H2S gas (generated by the first / second stage of sulfidation precipitation) to generate Bi2S3. After calcination, Bi2S3 is converted into Bi2O3, realizing the full recovery and recycling of Bi2O3. F. Oxidative hydrolysis polymerization: This process removes Bi... 3+ Liquid polyferric sulfate can be obtained by oxidizing, hydrolyzing, polymerizing, aging and post-treatment of the precipitated liquid.

[0007] The specific steps are as follows: A. Iron sludge pretreatment: The iron sludge is washed three times with pure water and then dewatered by pressure filtration. The filter cake is then crushed, dried at a constant temperature of 106℃ for 3.0 h, ground and passed through a 60-mesh sieve to obtain fine particles with a particle size of less than 250μm for later use. The iron sludge is a precipitate produced during the Fenton oxidation process to remove organic matter from wastewater. Its main component is Fe(OH)3, accounting for 65~80%.

[0008] B. First-stage sulfidation precipitation: FeS is added at a stirring speed of 120 r / min to carry out a first-stage sulfidation reaction. The amount of FeS added is calculated based on the initial molar concentrations of As and Hg in the waste acid, according to the As:Hg:S molar ratio of 1:(1.4~1.6):(1.4~1.6). The reaction mainly produces As2S3 and HgS precipitates. After vacuum filtration through a 0.45μm filter membrane to separate the slag and water, As and Hg are accurately removed from the waste acid. The main component of the sludge is As2S3, which is disposed of as hazardous waste. The waste acid is the waste acid wastewater generated from the non-ferrous metal smelting flue gas acid production workshop, specifically the waste acid generated from the copper smelting flue gas acid production workshop. Steps B to F are all carried out at a water temperature of 25±5℃.

[0009] C. Neutralization and Precipitation: Add the prepared iron sludge to neutralize the pH to 2-4, and promote Fe precipitation at a stirring speed of 120 r / min. 3+ With F - The reaction produces FeF3 precipitate, which is partially removed by mud-water separation; the sludge is mainly composed of FeF3 and is disposed of as hazardous waste.

[0010] D. Displacement reaction: Under a stirring speed of 120 r / min, iron powder is added according to the initial molar concentration of Cu in the waste acid, at a Cu:Fe molar ratio of 1:(1~1.2) to carry out the displacement reaction, thereby displacing Cu... 2+ The copper precipitate (copper sludge) is generated by displacement from the waste acid. After mud-water separation, Cu is removed from the waste acid. The copper sludge is washed with pure water 2-3 times to remove impurities and dried to constant weight to obtain copper powder with a copper content of 50-60%, which can be used as raw material for copper smelters.

[0011] E. Second-stage sulfidation precipitation: At a stirring speed of 120 r / min, add H2SO4 to adjust the acidity to 50~60 g / L, and continue to add FeS to carry out the second-stage sulfidation reaction. The amount of FeS added is calculated based on the initial molar concentrations of Pb, Zn and Cd in the waste acid, according to the molar ratio of Pb:Zn:Cd:S 1:1:1:(1~1.2). The reaction produces sulfide precipitates (mainly ZnS and PbS, with a small amount of CdS). After sludge-water separation, Pb, Zn and Cd are removed from the waste acid. The Zn and Pb rich sulfide slag (Zn and Pb contents of 19% and 12% respectively) is used as raw material for lead-zinc smelting plants.

[0012] F. Two-step precipitation: Cl is removed via a two-step precipitation method using bismuth oxide (Bi₂O₃) at a stirring speed of 120 r / min. - and F - First, the dosage of Bi₂O₃ added in the first step is based on the Cl content in the waste acid. - F - Initial molar concentration, according to (Bi₂O₃):(Cl - +F -The molar ratio was calculated to be 0.3:1. After stirring for 75 minutes, BiOCl and BiOF precipitates were formed (mainly BiOCl). Secondly, the amount of Bi2O3 added in the second step of precipitation was calculated as (Bi2O3):(Cl...) - +F - Calculated at a molar ratio of 0.7:1, after stirring for 120 min, BiOF and BiOCl precipitates (mainly BiOF) were generated. These were then separated by filtration. The BiOF and BiOCl precipitates were reacted with NaOH solution (NaOH concentration 2.75 mol / L, V(NaOH):m(precipitate) = 4 mL / g) at room temperature for 120 min, followed by separation, washing, and drying to obtain regenerated Bi2O3. Residual BiOF in the filtrate was observed. 3+ It reacts with H2S gas (generated by sulfide precipitation in the first / second stage) to form Bi2S3, and Bi2S3 is calcined at 600℃ to form Bi2O3; thus achieving full recovery and recycling of Bi2O3, except for Cl. - F - .

[0013] G. Oxidative Hydrolysis Polymerization: Liquid polyferric sulfate (PFS) can be prepared by a four-step reaction of FeSO4 and Fe2(SO4)3 solution involving oxidation, hydrolysis, polymerization, aging, and post-treatment; a. Oxidation: 30% H2O2 is slowly added at a liquid temperature of 25±3℃ and a stirring speed of 120 r / min to oxidize FeSO4 and Fe2(SO4)3 solution. 2+ Oxidized to Fe 3+ Dosage based on Fe 2+ All oxidized to Fe 3+ a. Oxidation time: 1-2 h; b. Hydrolysis: At a liquid temperature of 40-50℃ and a stirring speed of 200 r / min, the Fe content in the solution was controlled by adding Fe2(SO4)3 and H2SO4. 3+ The molar ratio of Fe2(SO4)3 to HSO4 is (4~5):1, the pH is maintained at 2.0~3.0, and hydrolysis is continued for 0.5~1 h; c. Polymerization: The solution is heated to 70℃ and stirred at 200 r / min for 2~3 h until the solution viscosity increases significantly; d. Maturation and post-treatment: The solution is cooled to room temperature and allowed to mature for 12~24 h to promote the polymerization of Fe2(SO4)3. Insoluble matter is removed by vacuum filtration through a 0.45μm filter membrane. The resulting brown liquid PFS meets the qualified product of "Polyferric Sulfate for Water Treatment" (GB / T 14591-2016).

[0014] Technical principle of the invention: A. Segmented sulfidation precipitation Ferrous sulfide (FeS) dissolves into Fe in polluted acid. 2+ and S 2- S 2- With H +When combined with H2S, it can react with As and heavy metal ions in the waste acid to form sulfide precipitates, as shown in the following reaction formula: As in waste acid is usually in the form of As 3+ And As 5+ When FeS is used to treat high-arsenic wastewater, it can act as a reducing agent to reduce As... 5+ Convert to As 3+ And S 2- And As 3+ It can rapidly form As2S3 precipitate, achieving As 3+ Effective removal. Utilizing the differences in solubility products of different metal sulfides, the lower the solubility product, the more preferentially it precipitates; by adjusting the pH and FeS dosage in stages, the metals precipitate sequentially according to their solubility products.

[0015] B. Neutralization and precipitation After adding iron sludge to the sewage, F - with Fe 3+ The reaction produces FeF3 precipitate, and the reaction formula is as follows: C. Displacement reaction Fe is more reactive than Cu and can displace copper; Fe is slightly more reactive than Pb and theoretically can displace Pb, but in practice the reaction efficiency is very low and a long reaction time is required; Fe is less reactive than Zn and cannot displace Zn. The reaction equation for Fe displacing Cu is as follows: D. Two-step precipitation After adding Bi2O3 to the waste acid, the dissolved Bi generated 3+ respectively with F - Cl - A selective precipitation reaction occurs, as shown in the following equation: Based on F - Cl - Physicochemical properties were assessed, and the BiOF and BiOCl precipitates were regenerated by alkaline hydrolysis with NaOH solution, enabling efficient recovery and recycling of Bi2O3. The reaction formula is as follows: The H2S gas generated from the first / second stage of sulfidation precipitation is introduced into the waste acid, reacting with the residual Bi. 3+ The reaction produces Bi₂S₃, which is then converted to Bi₂O₃ by high-temperature calcination, as shown in the following reaction formula: E. Oxidative hydrolytic polymerization Oxidation: Add 30% H2O2 to Fe2+ Oxidized to Fe 3+ (See the formula below), which simultaneously functions as both an oxidizer of organic matter and a reducer of substances.

[0016] Hydrolysis: Under acidic conditions, Fe2(SO4)3 hydrolyzes to form ferric hydroxide intermediate (see formula below). When SO4 2- When insufficient, Fe 3+ Hydrolysis will occur, generating high-valence hydroxyl iron complex ions.

[0017]

[0018] Polymerization: The intermediate ferric hydroxysulfate is further polymerized to produce polyferric sulfate with a high molecular weight (see formula below), usually represented by the chemical formula [Fe2(OH)]. n (SO4) 3-n / 2 ] m ,in n The number of hydroxyl groups, m This represents the degree of aggregation.

[0019] Compared with the prior art, the present invention has the following technical effects: 1. FeS replaces traditional H2S, Na2S and NaHS sulfiding agents, and solid waste iron sludge (main component Fe(OH)3) replaces traditional CaCO3, Ca(OH)2 and NaOH alkali agents, to achieve deep purification of waste acid and maximize the utilization of iron resources, reduce the cost of waste acid treatment, and generate no gypsum slag. 2. Using Fe to convert Cu 2+ The copper is precipitated by replacing the waste acid with elemental copper, thus achieving the directional separation and enrichment of Cu. 3. Under acidic wastewater conditions, F and Cl were efficiently removed, solving the technical bottleneck of the difficulty in efficiently removing F and Cl from acidic wastewater; 4. The prepared liquid polyferric sulfate meets the qualified product standard of "Polyferric Sulfate for Water Treatment" (GB / T 14591-2016), and has significant economic benefits. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0022] The method for deep purification and high-quality resource utilization of smelting waste acid described in this invention includes a first-stage sulfidation precipitation, neutralization precipitation, displacement reaction, a second-stage sulfidation precipitation, a two-step precipitation, and oxidative hydrolysis polymerization steps, specifically including: A. First-stage sulfide precipitation: FeS is added to the waste acid to carry out a first-stage sulfide reaction, resulting in first-stage sulfide precipitation liquid a and precipitate b. Precipitate b is treated as hazardous waste. B. Neutralization and precipitation: 1) After washing the iron mud with pure water and pressing and filtering, the resulting filter cake is crushed, dried and ground to obtain the prepared iron mud; 2) The prepared iron sludge is added to the first-stage sulfidation precipitation liquid a to carry out a neutralization reaction to obtain neutralized precipitation liquid c and precipitate d. Precipitate d is treated as hazardous waste. C. Displacement reaction: Iron powder is added to the neutralized and precipitated liquid c to carry out a displacement reaction, resulting in a displacement liquid e and elemental copper precipitate f. After removing impurities and drying, elemental copper precipitate f is used to obtain copper powder. D. Two-stage sulfidation precipitation: FeS and H2SO4 are added to the replacement liquid e to carry out a two-stage sulfidation reaction, resulting in a two-stage sulfidation precipitation liquid g and sulfide precipitate h. Sulfide precipitate h can be used as a raw material for lead-zinc smelters. E. Two-step precipitation: A certain amount of Bi2O3 is added to the two-stage sulfidation precipitation solution g to carry out the first precipitation reaction; then an appropriate amount of Bi2O3 is added to carry out the second precipitation reaction, obtaining the precipitation solution i and precipitate j; precipitate j is regenerated with NaOH solution to obtain Bi2O3 precipitant; Bi2O3 remains in the precipitation solution i. 3+ It reacts with H2S gas (generated by the first / second stage of sulfidation precipitation) to generate Bi2S3. After calcination, Bi2S3 is converted into Bi2O3, realizing the full recovery and recycling of Bi2O3. F. Oxidative hydrolysis polymerization: This process removes Bi... 3+ Liquid polyferric sulfate can be obtained by oxidizing, hydrolyzing, polymerizing, aging and post-treatment of the precipitated liquid.

[0023] The temperature of the first stage of the sulfidation reaction described in step A is 20~30℃.

[0024] The neutralization reaction described in step B involves adding iron sludge to neutralize the pH value to 2-4.

[0025] The neutralization reaction described in step B is carried out at a temperature of 20-30°C.

[0026] The temperature of the displacement reaction in step C is 20~30℃.

[0027] The two-stage sulfidation reaction described in step D is carried out under conditions of acidity of 50-60 g / L and stirring speed of 100-150 r / min.

[0028] The two-step precipitation reaction described in step E is carried out under the conditions of pH=2~3 and stirring speed of 100~150r / min.

[0029] The invention will be further illustrated below with specific implementation examples: The quality of the copper smelting wastewater used in this invention is shown in Table 1.

[0030] Table 1. Wastewater Quality from Copper Smelting

[0031] In all the following examples, all indicators of the liquid polyferric sulfate product were determined according to the methods specified in "Polyferric Sulfate for Water Treatment" (GB / T 14591-2016). The indicator requirements for liquid polyferric sulfate for water treatment are shown in Table 2.

[0032] Table 2 Product Specifications of Polyferric Sulfate Liquid Water Treatment Agent

[0033] Example 1

[0034] As attached Figure 1 The embodiment shown includes the following steps: A. Iron sludge pretreatment: The iron sludge is washed three times with pure water and then dewatered by pressure filtration. The filter cake is then crushed, dried at a constant temperature of 106℃ for 3.0 h, ground and passed through a 60-mesh sieve to obtain fine particles with a particle size of <250μm for later use. The iron sludge is a precipitate produced during the Fenton oxidation process to remove organic matter from wastewater. Its main component is Fe(OH)3, accounting for 65~80%.

[0035] B. First-stage sulfidation precipitation: FeS is added at a stirring speed of 120 r / min to carry out a first-stage sulfidation reaction. The amount of FeS added is calculated based on the initial molar concentrations of As and Hg in the waste acid, according to the As:Hg:S molar ratio of 1:(1.4~1.6):(1.4~1.6). The reaction mainly produces As2S3 and HgS precipitates. After vacuum filtration through a 0.45μm filter membrane for mud-water separation, As and Hg are removed from the waste acid. The main component of the sludge is As2S3, which is disposed of as hazardous waste. The waste acid is waste acid produced in the non-ferrous metal smelting flue gas acid production workshop, specifically waste acid produced in the copper smelting flue gas acid production workshop. Steps B to F are all carried out at a water temperature of 25±5℃.

[0036] C. Neutralization and Precipitation: Iron sludge is added to neutralize the pH to 2, and Fe is promoted by stirring at 120 r / min. 3+ With F - The reaction produces FeF3 precipitate, which is partially removed by mud-water separation; the main component of the sludge is FeF3.

[0037] D. Displacement reaction: Under a stirring speed of 120 r / min, iron powder is added according to the initial molar concentration of Cu in the waste acid, at a Cu:Fe molar ratio of 1:1.1, to carry out the displacement reaction, thereby displacing Cu... 2+ The copper precipitate (copper sludge) is generated by displacement from the waste acid. After mud-water separation, Cu is removed from the waste acid. The copper sludge is washed with pure water 2-3 times to remove impurities and dried to constant weight to obtain copper powder with a copper content of 50-60%, which can be used as raw material for copper smelters.

[0038] E. Second-stage sulfidation precipitation: At a stirring speed of 120 r / min, H2SO4 is added to adjust the acidity to 60 g / L, and FeS is added to carry out the second-stage sulfidation reaction. The amount of FeS added is calculated based on the initial molar concentrations of Pb, Zn, and Cd in the waste acid, according to the molar ratio of Pb:Zn:Cd:S of 1:1:1:1.1. The reaction produces sulfide precipitates (mainly ZnS and PbS, with a small amount of CdS). After sludge-water separation, Pb, Zn, and Cd are removed from the waste acid. The Zn- and Pb-rich sulfide slag is used as raw material for lead-zinc smelters.

[0039] F. Two-step precipitation: Cl- was removed via a two-step precipitation method using bismuth oxide (Bi₂O₃) at pH 2 and a stirring speed of 120 r / min. - and F - First, the dosage of Bi₂O₃ added in the first step is based on the Cl content in the waste acid. - F - Initial molar concentration, according to (Bi₂O₃):(Cl - +F - The molar ratio was calculated to be 0.3:1. After stirring for 75 minutes, BiOCl and BiOF precipitates were formed (mainly BiOCl). Secondly, the amount of Bi2O3 added in the second step of precipitation was calculated as (Bi2O3):(Cl...) - +F - Calculated at a molar ratio of 0.7:1, after stirring for 120 min, BiOF and BiOCl precipitates (mainly BiOF) were generated. These were then separated by filtration. The BiOF and BiOCl precipitates were reacted with NaOH solution (NaOH concentration 2.75 mol / L, V(NaOH):m(precipitate) = 4 mL / g) at room temperature for 120 min, followed by separation, washing, and drying to obtain regenerated Bi2O3. Residual BiOF in the filtrate was observed. 3+ It reacts with H2S gas (generated by sulfide precipitation in the first / second stage) to form Bi2S3, and Bi2S3 is calcined at 600℃ to form Bi2O3; thus achieving full recovery and recycling of Bi2O3, except for Cl. - F - .

[0040] G. Oxidative Hydrolysis Polymerization: Liquid polyferric sulfate (PFS) can be prepared by a four-step reaction of FeSO4 and Fe2(SO4)3 solution involving oxidation, hydrolysis, polymerization, aging, and post-treatment; a. Oxidation: 30% H2O2 is slowly added at a liquid temperature of 25±5℃ and a stirring speed of 120 r / min to oxidize FeSO4 and Fe2(SO4)3 solution. 2+ Oxidized to Fe 3+ Dosage based on Fe 2+ All oxidized to Fe 3+ a. Oxidation time: 2 h; b. Hydrolysis: At a liquid temperature of 40℃ and a stirring speed of 200 r / min, the Fe content in the solution was controlled by adding Fe2(SO4)3 and H2SO4. 3+ The molar ratio of Fe2(SO4)3 to HSO4 was 4:1, and the pH was maintained at 2.0 for 1 h of continuous hydrolysis. c. Polymerization: The solution was heated to 70℃ and stirred at 200 r / min for 3 h until the viscosity of the solution increased significantly. d. Maturation and post-treatment: The solution was cooled to room temperature and allowed to stand for 24 h to promote the polymerization of Fe2(SO4)3. Insoluble matter was removed by vacuum filtration through a 0.45 μm filter membrane. The resulting brown liquid PFS met the requirements of "Polyferric Sulfate for Water Treatment" (GB / T 14591-2016).

[0041] Example 2

[0042] Steps A, D, E, F, and G in this embodiment are the same as in Example 1; in step B, the molar ratio of As:Hg:S is 1:1.6:1.6; in step C, iron sludge is added to neutralize the pH to 2-4; the rest of steps B and C are the same as in Example 1; a brownish liquid PFS can be obtained, which meets the qualified product of "Polyferric Sulfate for Water Treatment" (GB / T 14591-2016).

[0043] Example 3

[0044] Steps A, C, E, F, and G in this embodiment are the same as in Example 1; in step B, the molar ratio of As:Hg:S is 1:1.6:1.6, and in step D, iron powder is added according to the molar ratio of Cu:Fe of 1:(1~1.2) to carry out the displacement reaction. The rest of steps B and D are the same as in Example 1. A brown liquid PFS can be obtained, which meets the qualified product of "Polyferric Sulfate for Water Treatment" (GB / T 14591-2016).

[0045] Example 4

[0046] Steps A, C, D, F, and G in this embodiment are the same as in Example 1; in step B, the molar ratio of As:Hg:S is 1:1.6:1.6; in step E, H2SO4 is added to adjust the acidity to 50~60 g / L and the molar ratio of Pb:Zn:Cd:S is 1:1:1:(1~1.2); the rest of steps B and E are the same as in Example 1; a brownish-yellow liquid PFS can be obtained, which meets the qualified product of "Water Treatment Agent Polyferric Sulfate" (GB / T 14591-2016).

[0047] Example 5

[0048] Steps A, C, D, E, and G in this embodiment are the same as in Example 1. In step B, the molar ratio of As:Hg:S is 1:1.6:1.6; in step F, the pH is 2-3. The rest of steps B and F are the same as in Example 1. A brown liquid PFS can be obtained, which meets the qualified product of "Polyferric Sulfate for Water Treatment" (GB / T 14591-2016).

[0049] Example 6

[0050] Steps A, C, D, E, and F in this embodiment are the same as in Example 1. Step B: As:Hg:S molar ratio 1:1.6:1.6; Step G: a. Oxidation time 1-2 h; b. Hydrolysis: liquid temperature 40-50℃, Fe... 3+ The molar ratio of HSO4 is (4~5):1, the pH is 2.0~3.0, and the hydrolysis time is 0.5~1 h; c. Polymerization: heat to 70℃ and stir for 2~3 h; d. Let stand for 12~24 h; steps B and G are the same as in Example 1; a brown liquid PFS can be obtained, which meets the qualified product of "Polyferric Sulfate for Water Treatment" (GB / T 14591-2016).

[0051] Example 7

[0052] Following step F in Example 1, the Bi2O3 regenerated from BiOF / BiOCl precipitate and Bi2S3 precipitate was uniformly mixed with a small amount of fresh Bi2O3, and five batches of waste acid were subjected to Cl removal. - F - Experiment, Cl - and F - The removal efficiency remained above 85%, indicating that the regenerated Bi2O3 maintained excellent performance.

Claims

1. A method for deep purification and high-quality resource utilization of smelting waste acid, characterized in that, The method for deep purification and high-quality resource utilization of smelting waste acid includes a first-stage sulfidation precipitation, neutralization precipitation, displacement reaction, a second-stage sulfidation precipitation, a two-step precipitation, and oxidative hydrolysis polymerization steps, specifically including: A. First-stage sulfide precipitation: FeS is added to the waste acid to carry out a first-stage sulfide reaction, resulting in first-stage sulfide precipitation liquid a and precipitate b. Precipitate b is treated as hazardous waste. B. Neutralization and precipitation: 1) After washing the iron mud with pure water and pressing and filtering, the resulting filter cake is crushed, dried and ground to obtain the prepared iron mud; 2) The prepared iron sludge is added to the first-stage sulfidation precipitation liquid a for neutralization reaction, and the pH value is neutralized to 2~4 to obtain neutralized precipitation liquid c and precipitate d. Precipitate d is treated as hazardous waste. C. Displacement reaction: Iron powder is added to the neutralized and precipitated liquid c to carry out a displacement reaction, resulting in a displacement liquid e and elemental copper precipitate f. After removing impurities and drying, elemental copper precipitate f is used to obtain copper powder. D. Two-stage sulfidation precipitation: FeS and H2SO4 are added to the replacement liquid e to carry out a two-stage sulfidation reaction, resulting in a two-stage sulfidation precipitation liquid g and sulfide precipitate h. Sulfide precipitate h can be used as a raw material for lead-zinc smelters. E. Two-step precipitation: Bi₂O₃ is added to the liquid g after the two-stage sulfidation precipitation to carry out the first precipitation reaction; then an appropriate amount of Bi₂O₃ is added to carry out the second precipitation reaction, resulting in liquid i after precipitation and precipitate j; precipitate j is regenerated with NaOH solution to obtain Bi₂O₃ precipitant; Bi₂O₃ remains in liquid i after precipitation. 3+ It reacts with H2S gas to generate Bi2S3, and Bi2S3 is calcined to generate Bi2O3, realizing the full recovery and recycling of Bi2O3; H2S gas is generated by the first and second stage sulfide precipitation. F. Oxidative hydrolysis polymerization: This process removes Bi... 3+ Liquid polyferric sulfate can be obtained by oxidizing, hydrolyzing, polymerizing, aging and post-treatment of the precipitated liquid.

2. The method for deep purification and high-quality resource utilization of smelting waste acid according to claim 1, characterized in that, The temperature of the first stage of the sulfidation reaction described in step A is 20~30℃.

3. The method for deep purification and high-quality resource utilization of smelting waste acid according to claim 1, characterized in that, The neutralization reaction described in step B is carried out at a temperature of 20-30°C.

4. The method for deep purification and high-quality resource utilization of smelting waste acid according to claim 1, characterized in that, The temperature of the displacement reaction in step C is 20~30℃.

5. The method for deep purification and high-quality resource utilization of smelting waste acid according to claim 1, characterized in that, The two-stage sulfidation reaction described in step D is carried out under conditions of acidity of 50-60 g / L and stirring speed of 100-150 r / min.

6. The method for deep purification and high-quality resource utilization of smelting waste acid according to claim 1, characterized in that, The two-step precipitation reaction described in step E is carried out under conditions of pH = 2~3 and stirring speed of 100~150 r / min, regenerating Bi2O3 for Cl. － and F － The removal rates were all above 85%.

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