Separation method of impurity arsenic in process of treating high-arsenic indium-containing zinc oxide smoke dust by wet process

Abstract

The invention discloses a method for separating impurity arsenic in the process of treating high-arsenic indium-containing zinc oxide smoke dust by a wet process, which comprises the following steps: when pyrogenic smelting and fuming volatilization treatment are carried out on jarosite slag and high-acid leaching slag produced by zinc hydrometallurgy, controlling the air leakage of a waste heat boiler to oxidize arsenic in the smoke dust into pentavalent arsenic; high-arsenic indium-containing zinc oxide smoke dust obtained through dust collection is treated in a two-stage leaching mode; the arsenic content of the first-stage leaching solution is controlled to be 0.5-1.0 g / L, the pH value of the second-stage leaching solution is controlled to be 1.6-1.8, the indium content in the first-stage leaching solution and the indium content in the second-stage leaching solution are both smaller than 5 mg / L, indium loss is effectively prevented, and second-stage leaching residues serve as lead and indium enrichment to subsequently recover valuable components lead and indium; adding a ferric sulfate solution into the second-section leachate to quickly generate ferric arsenate precipitate, combining the filtered filtrate with the first-section leachate, further deeply purifying to remove arsenic until the arsenic content is less than 1.0 mg / L, subsequently purifying to remove fluorine and chlorine, and electrolyzing to produce metal zinc.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for separating impurity arsenic in the process of treating high-arsenic and indium-containing zinc oxide dust by a hydroprocess. Background Art

[0002] The iron alum slag and high-acid leaching slag produced by wet zinc smelting are hazardous solid wastes. Smelting and fume volatilization treatment is currently the most ideal harmless treatment method. At the same time, the zinc contained in the iron alum slag and high-acid leaching slag can be recovered in the form of zinc oxide smoke. The valuable elements lead and indium in the slag are also enriched in the zinc oxide smoke.

[0003] The most convenient way to recover zinc, lead and indium from this type of zinc oxide dust is to use a sulfuric acid system for comprehensive treatment, and its process principle is basically the same as the current wet zinc smelting process principle. However, when the pyrometallurgical method is used to harmlessly treat iron alum slag and high-acid leaching slag, a large amount of arsenic impurities contained in the slag also volatilize into the zinc oxide dust, which brings the following problems to the subsequent wet treatment of zinc oxide dust to recover zinc and indium: 1) The arsenic-containing zinc oxide is de-arsenified by sulfuric acid roasting, which is costly and only suitable for the production of zinc sulfate salt products, and the market is saturated; 2) The arsenic-containing zinc oxide is de-arsenicized by alkaline leaching, and the cost of sodium hydroxide raw materials is relatively high.

[0004] In the prior art, the following methods are usually used to remove arsenic from the solution: 1) In a high-pressure container, arsenic is precipitated and removed in the form of well-crystallized scorodite by a high-temperature precipitation method. Arsenic can be precipitated and removed under acidic conditions, such as the Chinese invention patent "A method for removing arsenic from an acidic arsenic-containing solution using iron salts" (CN201910328869.1), but its equipment investment is large and its operating cost is high; 2) In a normal pressure container, ferrous ions are added, and crystalline ferric arsenate precipitation is formed to remove arsenic by controlling the supersaturation. This method is usually used to treat trivalent arsenic solutions, and the process conditions are strict. It is necessary to use an oxidant to oxidize trivalent arsenic and ferrous ions together, and the pH value of the resulting precipitate is relatively high. Its process conditions will cause a large loss of indium in the leachate.

[0005] In order to solve the problem that impurity arsenic is difficult to remove during wet treatment of high-arsenic and indium-containing zinc oxide dust, which affects the comprehensive recovery of zinc and indium, a method for separating impurity arsenic during wet treatment of high-arsenic and indium-containing zinc oxide dust is urgently needed in the prior art. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for separating impurity arsenic in the process of treating high-arsenic and indium-containing zinc oxide dust by a wet process.

[0007] The object of the present invention is achieved through the following technical scheme: a method for separating impurity arsenic in the process of treating high-arsenic indium-containing zinc oxide dust by a wet process, comprising the following steps: 1) When pyrometallurgical smelting and fume volatilization are used to treat the iron alum slag and high-acid leaching slag produced by wet zinc smelting, the air leakage of the waste heat boiler is controlled to fully burn the carbon monoxide in the flue gas, eliminate the subsequent dangerous hidden dangers of high-temperature flue gas in the dust collection system, and oxidize the arsenic in the flue dust into pentavalent arsenic; 2) The high-arsenic and indium-containing zinc oxide dust obtained by dust collection is treated by a two-stage leaching method; in the first stage, waste electrolyte from zinc smelting is added for leaching, and the amount of waste electrolyte from zinc smelting added is based on the arsenic content in the leaching solution being in the range of 0.5-1.0 g / L, and a first-stage leaching residue and a first-stage leaching solution are obtained through liquid-solid separation, and the indium content in the first-stage leaching solution is less than 5 mg / L; waste electrolyte from zinc smelting is added to the first-stage leaching residue for a second stage leaching, and the amount of waste electrolyte from zinc smelting added is based on the pH value of the leaching solution being in the range of 1.6-1.8, and a second-stage leaching residue and a second-stage leaching solution are obtained through liquid-solid separation, and the indium content in the second-stage leaching solution is less than 5 mg / L; 3) placing the second-stage leaching solution obtained in step 2) into a mechanical stirring tank, adding ferric sulfate solution to the mechanical stirring tank at a molar ratio of iron to arsenic of 1 to precipitate and remove arsenic, the stirring speed is 200-400 r / min, the precipitation temperature is 80-90°C, the ferric sulfate solution is added within 30 minutes, and after all the ferric sulfate solution is added, the slurry is aged for 1 hour, the aging temperature is 80-90°C, the stirring speed during the aging period is 60-90 r / min, and after the aging is completed, the liquid and solid are separated to obtain a microcrystalline ferric arsenate precipitate and a liquid after the precipitation and arsenic removal, and the residual arsenic in the liquid after the precipitation and arsenic removal is 0.8-1.5 g / L; 4) The precipitated arsenic removal liquid obtained in step 3) is combined with the first-stage leaching liquid obtained in step 2), and the arsenic removal is purified by lime-ferrous salt method in a mechanical stirring tank, ferrous sulfate solid reagent is added at a time according to the iron-arsenic molar ratio of 4, air is blown in for oxidation, and the pH value of the slurry is adjusted to 3.5-4.0 with lime milk. The purification precipitation temperature is 60-80°C, and the stirring speed is 60-90 r / min. When the arsenic in the mixed solution is reduced to below 1.0 mg / L, the iron-arsenic slag and the purified arsenic removal liquid are obtained by liquid-solid separation.

[0008] The high-arsenic and indium-containing zinc oxide dust collected in step 2) contains 3%-8% arsenic, 40%-50% zinc, and 0.1%-0.3% indium.

[0009] In step 3), the concentration of the ferric sulfate solution added to the mechanical stirring tank is 10 mol / L.

[0010] In step 3), the ferric sulfate solution is added by gravity flow from a high-level tank or by pumping.

[0011] The invention has the following beneficial effects: 1) the arsenic content of the first-stage leaching solution is controlled to be 0.5-1.0 g / L, the pH value of the second-stage leaching solution is 1.6-1.8, and the indium content in the first-stage leaching solution and the second-stage leaching solution is less than 5 mg / L, thereby effectively preventing the loss of indium caused by the loss of the valuable element indium with the first-stage leaching solution and the second-stage leaching solution; 2) the second-stage leaching solution contains 150 g / L of zinc and is a concentrated electrolyte solution. Arsenic in the solution is easily polymerized. After adding ferric sulfate solution, ferric arsenate precipitation is quickly generated. The precipitation is a microcrystalline precipitation between an amorphous state and a well-crystalline state. The filtration rate can reach 20-30 L / (min·m 2 ), although the particle size is small, it is still easy to filter; 3) The arsenic content of the liquid after purification and arsenic removal obtained by the method of the present invention is less than 1.0 mg / L, and then it is purified to remove fluorine and chlorine, and then further electrolytic method is used to produce metallic zinc, and the second-stage leaching slag is subsequently used to recover lead and indium, which is beneficial to the comprehensive recovery of zinc and indium. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is the XRD pattern of iron arsenate microcrystal precipitation sample 1; Figure 2 This is the XRD pattern of iron arsenate microcrystal precipitation sample 2. DETAILED DESCRIPTION

[0013] The present invention is described in detail below with reference to the accompanying drawings. Example 1

[0014] A method for separating impurity arsenic in the process of treating high-arsenic indium-containing zinc oxide dust by a wet process comprises the following steps: 1) When pyrometallurgical smelting and fume volatilization are used to treat the iron alum slag and high-acid leaching slag produced by wet zinc smelting, the air leakage of the waste heat boiler is controlled to fully burn the carbon monoxide in the flue gas, eliminate the subsequent dangerous hidden dangers of high-temperature flue gas in the dust collection system, and oxidize the arsenic in the flue dust into pentavalent arsenic; 2) The high-arsenic and indium-containing zinc oxide dust obtained by dust collection contains 8% arsenic, 40% zinc and 0.3% indium, and the dust is treated by a two-stage leaching method; in the first stage, waste electrolyte of zinc smelting is added for leaching, and the waste electrolyte of zinc smelting is added until the arsenic content in the leaching solution is 0.966 g / L, and a first-stage leaching residue and a first-stage leaching solution are obtained through liquid-solid separation, and the indium content of the first-stage leaching solution is 4.95 mg / L; waste electrolyte of zinc smelting is added to the first-stage leaching residue for the second stage leaching, and the waste electrolyte of zinc smelting is added until the pH value of the leaching solution is 1.79, and a second-stage leaching residue and a second-stage leaching solution are obtained through liquid-solid separation, and the indium content of the second-stage leaching solution is 2.01 mg / L; lead and indium are subsequently recovered from the second-stage leaching residue; 3) The second-stage leachate obtained in step 2) is added with a 10 mol / L ferric sulfate solution at a molar ratio of iron to arsenic of 1 to remove arsenic by precipitation. The precipitation process is carried out in a mechanical stirring tank with a stirring speed of 400 r / min and a precipitation temperature of 90°C. No oxidant needs to be added during the precipitation process, and no neutralizer needs to be added to adjust the acidity. The ferric sulfate solution is added by gravity in a high-level tank. The ferric sulfate solution is added within 30 minutes. After all the ferric sulfate solution is added, the slurry is aged for 1 hour at an aging temperature of 90°C. The stirring speed during the aging period is 90 r / min. After the aging is completed, liquid-solid separation is performed to obtain a microcrystalline ferric arsenate precipitate (see XRD spectrum). Figure 1 ) and the liquid after arsenic removal by precipitation. The residual arsenic in the liquid after arsenic removal by precipitation is 0.787 g / L. The ferric arsenate precipitate is disposed of in a rigid landfill in accordance with GB 18598-2019; 4) The precipitated arsenic removal liquid obtained in step 3) is combined with the first-stage leaching liquid obtained in step 2), and the arsenic removal is purified by lime-ferrous salt method in a mechanical stirring tank, and ferrous sulfate solid reagent is added at a time according to the iron-arsenic molar ratio of 4, air is blown in for oxidation, and the pH value of the slurry is adjusted to 4.0 with lime milk, the purification precipitation temperature is 80°C, the stirring speed is 90 r / min, and the arsenic in the mixed solution is reduced to 0.80 mg / L after 240 minutes of reaction, and the iron-arsenic slag and the purified arsenic removal liquid are separated by liquid and solid; the iron-arsenic slag is disposed of in a flexible landfill after stabilization pretreatment according to GB 18598-2019; the purified arsenic removal liquid is sent for purification and removal of fluorine and chlorine, and further electrolysis is used to produce metallic zinc. Example 2

[0015] A method for separating impurity arsenic in the process of treating high-arsenic indium-containing zinc oxide dust by a wet process comprises the following steps: 1) When pyrometallurgical smelting and fume volatilization are used to treat the iron alum slag and high-acid leaching slag produced by wet zinc smelting, the air leakage of the waste heat boiler is controlled to fully burn the carbon monoxide in the flue gas, eliminate the subsequent dangerous hidden dangers of high-temperature flue gas in the dust collection system, and oxidize the arsenic in the flue dust into pentavalent arsenic; 2) The arsenic-containing zinc oxide dust obtained by dust collection contains 3% arsenic, 50% zinc and 0.1% indium, and the dust is treated by a two-stage leaching method; in the first stage, waste electrolyte from zinc smelting is added for leaching, and the amount of waste electrolyte from zinc smelting is such that the arsenic content in the leaching solution is 0.5 g / L, and a first-stage leaching residue and a first-stage leaching solution are obtained through liquid-solid separation; waste electrolyte from zinc smelting is added to the first-stage leaching residue for a second stage leaching, and the amount of waste electrolyte from zinc smelting is such that the pH value of the leaching solution is 1.6, and a second-stage leaching solution and a second-stage leaching residue are obtained through liquid-solid separation; lead and indium are subsequently recovered from the second-stage leaching residue; 2) The arsenic-containing zinc oxide dust obtained by dust collection contains 3% arsenic, 50% zinc and 0.1% indium, and the dust is treated by a two-stage leaching method; in the first stage, waste electrolyte of zinc smelting is added for leaching, and the waste electrolyte of zinc smelting is added until the arsenic content in the leaching solution is 0.53 g / L, and a first-stage leaching residue and a first-stage leaching solution are obtained through liquid-solid separation, and the indium content in the first-stage leaching solution is 2.12 mg / L; waste electrolyte of zinc smelting is added to the first-stage leaching residue for the second stage leaching, and the waste electrolyte of zinc smelting is added until the pH value of the leaching solution is 1.6, and a second-stage leaching residue and a second-stage leaching solution are obtained through liquid-solid separation, and the indium content in the second-stage leaching solution is 1.7 mg / L; lead and indium are subsequently recovered from the second-stage leaching residue; 3) The second-stage leachate obtained in step 2) is added with a 10 mol / L ferric sulfate solution at a molar ratio of iron to arsenic of 1 to remove arsenic by precipitation. The precipitation process is carried out in a mechanical stirring tank with a stirring speed of 200 r / min and a precipitation temperature of 80°C. No oxidant needs to be added during the precipitation process, and no neutralizer needs to be added to adjust the acidity. The ferric sulfate solution is added by gravity in a high-level tank. The ferric sulfate solution is added within 30 minutes. After all the ferric sulfate solution is added, the slurry is aged for 1 hour at an aging temperature of 80°C. The stirring speed during the aging period is 60 r / min. After the aging is completed, liquid-solid separation is performed to obtain a microcrystalline ferric arsenate precipitate (see XRD spectrum). Figure 2 ) and the liquid after arsenic removal by precipitation. The residual arsenic in the liquid after arsenic removal by precipitation is 1.146 g / L. The ferric arsenate precipitate is disposed of in a rigid landfill in accordance with GB 18598-2019; 4) The precipitated arsenic removal liquid obtained in step 3) is combined with the first-stage leaching liquid obtained in step 2), and the arsenic removal is purified by lime-ferrous salt method in a mechanical stirring tank, and ferrous sulfate solid reagent is added at a time according to the iron-arsenic molar ratio of 4, air is blown in for oxidation, and the pH value of the slurry is adjusted to 3.5 with lime milk. The purification precipitation temperature is 60°C, the stirring speed is 60 r / min, and the arsenic in the mixed solution is reduced to 0.56 mg / L after 300 minutes of reaction. The iron-arsenic slag and the purified arsenic removal liquid are separated by liquid and solid; the iron-arsenic slag is disposed of in a flexible landfill after stabilization pretreatment in accordance with GB 18598-2019; the purified arsenic removal liquid is sent for purification and removal of fluorine and chlorine, and further electrolysis is used to produce metallic zinc.

[0016] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for separating impurity arsenic in the process of treating high-arsenic indium zinc oxide dust by wet process, characterized in that The steps include: 1) When pyrometallurgical smelting and fume volatilization are used to treat the iron alum slag and high-acid leaching slag produced by wet zinc smelting, the air leakage of the waste heat boiler is controlled to fully burn the carbon monoxide in the flue gas, eliminate the subsequent dangerous hidden dangers of high-temperature flue gas in the dust collection system, and oxidize the arsenic in the flue dust into pentavalent arsenic; 2) The high-arsenic and indium-containing zinc oxide dust obtained by dust collection is treated by a two-stage leaching method; in the first stage, waste electrolyte from zinc smelting is added for leaching, and the amount of waste electrolyte from zinc smelting added is based on the arsenic content in the leaching solution being in the range of 0.5-1.0 g / L, and a first-stage leaching residue and a first-stage leaching solution are obtained through liquid-solid separation, and the indium content in the first-stage leaching solution is less than 5 mg / L; waste electrolyte from zinc smelting is added to the first-stage leaching residue for a second stage leaching, and the amount of waste electrolyte from zinc smelting added is based on the pH value of the leaching solution being in the range of 1.6-1.8, and a second-stage leaching residue and a second-stage leaching solution are obtained through liquid-solid separation, and the indium content in the second-stage leaching solution is less than 5 mg / L; 3) placing the second-stage leaching solution obtained in step 2) into a mechanical stirring tank, adding ferric sulfate solution to the mechanical stirring tank at a molar ratio of iron to arsenic of 1 to precipitate and remove arsenic, the stirring speed is 200-400 r / min, the precipitation temperature is 80-90°C, the ferric sulfate solution is added within 30 minutes, and after all the ferric sulfate solution is added, the slurry is aged for 1 hour, the aging temperature is 80-90°C, the stirring speed during the aging period is 60-90 r / min, and after the aging is completed, the liquid and solid are separated to obtain a microcrystalline ferric arsenate precipitate and a liquid after the precipitation and arsenic removal, and the residual arsenic in the liquid after the precipitation and arsenic removal is 0.8-1.5 g / L; 4) The precipitated arsenic removal liquid obtained in step 3) is combined with the first-stage leaching liquid obtained in step 2), and the arsenic removal is purified by lime-ferrous salt method in a mechanical stirring tank, ferrous sulfate solid reagent is added at a time according to the iron-arsenic molar ratio of 4, air is blown in for oxidation, and the pH value of the slurry is adjusted to 3.5-4.0 with lime milk. The purification precipitation temperature is 60-80°C, and the stirring speed is 60-90 r / min. When the arsenic in the mixed solution is reduced to below 1.0 mg / L, the iron-arsenic slag and the purified arsenic removal liquid are obtained by liquid-solid separation.

2. The method for separating impurity arsenic during the wet process treatment of high-arsenic indium-containing zinc oxide dust according to claim 1, characterized in that: The high-arsenic and indium-containing zinc oxide dust collected in step 2) contains 3%-8% arsenic, 40%-50% zinc, and 0.1%-0.3% indium.

3. The method for separating impurity arsenic during the wet process treatment of high-arsenic indium-containing zinc oxide dust according to claim 1, characterized in that: In step 3), the concentration of the ferric sulfate solution added to the mechanical stirring tank is 10 mol / L.

4. The method for separating impurity arsenic during the wet process treatment of high-arsenic indium-containing zinc oxide dust according to claim 1, characterized in that: In step 3), the ferric sulfate solution is added by gravity flow from a high-level tank or by pumping.

Images