Process for recovering zinc, nickel, cadmium, copper and chlorine in high-chlorine zinc slag

Abstract

The invention discloses a process for recovering zinc, nickel, cadmium, copper and chlorine in high-chlorine zinc slag. The process comprises the following steps: S1, four-stage reverse water washing; s2, removing impurities from water washing liquid; s3, concentrating and crystallizing the impurity-removed liquid; s4, leaching the washed mixed slag; s5, neutralizing the leachate to remove arsenic and iron; s6, replacing to remove copper, cadmium and nickel; and S7, concentrating and crystallizing the copper-cadmium-nickel-removed solution. According to the method, the technical bottleneck problem that the high-chlorine zinc slag is used for recovering zinc and discarding chlorine resources by applying a traditional zinc hydrometallurgy process technology is solved, and the environment-friendly process technology for recovering zinc and chlorine at low cost, producing ammonium chloride and zinc sulfate products and realizing zero emission of three wastes is realized. And meanwhile, valuable metals such as lead, cadmium and copper in the high-chlorine zinc slag are enriched and recycled.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource treatment, and particularly relates to a process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag. Background Art

[0002] In recent years, with the rapid growth of the demand for zinc, secondary zinc resources have become an important raw material for zinc production. Typical secondary zinc resources mainly include secondary zinc oxide fume, blast furnace gas ash, and steelmaking electric furnace fume. These resources can make up for the shortage of primary zinc resources, but they generally have problems such as high fluorine and chlorine impurity content and complex composition. Among them, high-chlorine zinc slag, as the blast furnace dust collected by wet scrubbers, bag filters, electrostatic precipitators, etc. from the soot discharged during the non-ferrous and ferrous metallurgical processes, contains a large amount of valuable metal elements such as nickel, lead, copper, and zinc, and has a high comprehensive recovery value. If it can be recycled, it will create considerable economic value, alleviate the resource crisis, and reduce environmental pollution.

[0003] The existing processes for treating smelting soot mainly rely on wet acid leaching, which consumes a large amount of acid during the process, and most of the chloride ions will enter the leaching solution and be directly discharged finally during the leaching process. If the chloride ion content in the leaching solution is relatively high, it will be enriched during the zinc recovery process, affecting the quality of zinc products, and the direct discharge of chloride ions without recycling will seriously endanger the ecological environment. Although there are innovations in the research of treatment methods: one is that a patent adopts a pyro-hydrometallurgical combined process, and the valuable elements in high-arsenic copper smelting soot are comprehensively recovered through the processes of (oxygen-enriched) roasting → leaching → extraction → replacement → crystallization, and the recovery rates of zinc, copper, lead, and tin in the smelting soot are all above 95%. However, the process is complex, the equipment investment is large, the energy consumption is high, the sulfuric acid consumption is large, and a large amount of sulfuric acid waste liquid is generated; the other is that Li Xiaoling et al. from Guangxi University (Li Xiao. Research on the recovery of copper and zinc from high-chlorine smelting soot. Guangxi University, 2014) adopted a full-wet process technology to recover copper and zinc from high-chlorine smelting soot, and obtained cathode copper and zinc sulfate monohydrate with good apparent quality and a purity greater than 98.16%. However, this method has the following deficiencies: (1) Since it is first alkali-washed and then sulfuric acid leached, the sulfuric acid consumption is large; (2) The chlorine-containing liquid generated in the process is directly discharged, polluting the environment and wasting resources; (3) The newly added impurity sodium carbonate waste liquid in the process needs to be treated separately, thus increasing the operating cost. Summary of the Invention

[0004] The main object of the present invention is to propose a process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag, solve the technical bottleneck problem of using traditional wet zinc smelting process technology to recover zinc from high-chlorine zinc slag and discard chlorine resources, realize the low-cost recovery of zinc and chlorine, produce ammonium chloride and zinc sulfate products, and at the same time enrich the valuable metals such as lead, cadmium, and copper in the high-chlorine zinc slag and make them recycled again.

[0005] To achieve the above object, the present invention provides a process for recovering zinc, nickel, cadmium, copper and chlorine from high-chlorine zinc slag, comprising the following steps:

[0006] S1. Perform four-stage reverse water washing on the high-chlorine zinc slag, and after solid-liquid separation, obtain washing liquid and washing residue;

[0007] S2. Remove impurities from the washing liquid obtained in step S1, and filter to obtain impurity-removing residue and impurity-removing liquid. Mix the impurity-removing residue with the washing residue obtained in step S1 to obtain a washing mixed residue;

[0008] S3. Concentrate and crystallize the impurity-removing liquid: Distill and concentrate the purified liquid obtained in step S2 to obtain ammonium chloride products. The water vapor is cooled to obtain condensed water and used for washing the high-chlorine zinc slag in step S1;

[0009] S4. Leach the washing mixed residue obtained in step S2: Mix the sulfuric acid solution with the washing mixed residue, stir in a stirrer, add hydrogen peroxide during the stirring process, and after stirring, perform solid-liquid separation to obtain a leaching solution and lead sulfate slag;

[0010] S5. Neutralize and remove arsenic and iron from the leaching solution obtained in step S4: Add zinc oxide powder to the leaching solution, adjust the pH value, stir and filter to obtain arsenic and iron slag and iron-removing liquid;

[0011] S6. Replace and remove copper, cadmium and nickel: Add activated zinc powder or nickel collector to the iron-removing liquid obtained in step S5, and successively replace copper, cadmium and nickel, and at the same time obtain a copper, cadmium and nickel-removing liquid;

[0012] S7. Concentrate and crystallize the copper, cadmium and nickel-removing liquid: Distill and concentrate the copper, cadmium and nickel-removing liquid in step S6 to obtain zinc sulfate products. The water vapor is cooled to obtain condensed water and used for washing the high-chlorine zinc slag in step S1.

[0013] Preferably, in step S1, the parameters of the four-stage reverse water washing are: the water washing temperature is 10-80°C, the weight ratio of water to high-chlorine zinc slag is 3-10:1, and the water washing stirring time is 1-6 h.

[0014] Preferably, before performing step S1, first perform material property analysis on the high-chlorine zinc slag, analyze the components in the high-chlorine zinc slag, and determine the elements with recycling value in the high-chlorine zinc slag; the analysis method is: first vacuum-dry the high-chlorine slag raw material at 105°C until constant weight, and then put it into a ball mill and crush it to a particle size where 80% or more is 200 mesh; perform chemical titration analysis, main chemical element content analysis and phase analysis on the crushed high-chlorine zinc slag respectively.

[0015] Preferably, the method for removing impurities from the washing solution in step S2 is as follows: at 10-80°C, add soluble ferric chloride in an amount of 2-15 times the molar amount of arsenic in the washing solution, stir for 0.5-2 h, then add hydrogen peroxide in an amount of 2-5 times the total molar amount of iron in the washing solution, stir for 0.5-2 h, add ammonia water with a concentration of 20 wt% to adjust the pH value to 5.0-8.0, stir for 0.5-2 h, and filter to obtain impurity removal slag and impurity removal solution.

[0016] Preferably, the method for leaching the washed mixed slag in step S4 is as follows: at 10-80°C, mix a sulfuric acid solution with a concentration of 20-98 wt% and the washed mixed slag at a weight ratio of 2-10:1, stir in a stirrer, add hydrogen peroxide with a weight of 1%-8% of the washed mixed slag during the stirring process, stir for 1-6 h, and then perform solid-liquid separation to obtain a leaching solution and lead sulfate slag.

[0017] Preferably, in step S5, the method for neutralizing and removing arsenic and iron from the leaching solution is as follows: at 10-80°C and under stirring, add zinc oxide powder to the leaching solution, adjust the pH value of the acidolysis solution to 2.0-5.5, continue to stir for 0.5-2 h, and then filter to obtain arsenic and iron slag and iron removal solution.

[0018] Preferably, in step S6, the method for replacing and removing copper, cadmium, and nickel is as follows: at 10-80°C and under stirring, add activated zinc powder or nickel collector in an amount of 1-4 times the molar amount of copper, cadmium, and nickel in the iron removal solution, stir for 0.5-3 h, and then replace copper, cadmium, and nickel successively.

[0019] Preferably, before performing step S1, it is necessary to measure the dechlorination rate of the high-chlorine zinc slag during washing. The measurement method is as follows: heat to a certain temperature in a water bath, then slowly add a certain mass of high-chlorine zinc slag and start timing; the stirring intensity should be such that the high-chlorine zinc slag can be stirred into the solution without precipitation; after stirring for the specified time, take out the beaker from the water bath, filter the slurry, and rinse with a certain amount of water; dry and weigh the filter residue and measure the chlorine mass fraction therein, and calculate the chlorine leaching rate, that is, the dechlorination rate, according to the measurement results.

[0020] Preferably, before performing step S1, the high-chlorine zinc slag needs to be ground first, and at the same time, measure the influence of the grinding fineness on the dechlorination rate of the high-chlorine zinc slag, and determine that the optimal grinding fineness is 80 mesh.

[0021] Preferably, in step S2, when the pH value is adjusted to 7.5, a precipitate is formed and filtered to obtain a solution containing ammonium chloride.

[0022] Due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0023] (1) The present invention adopts a process technology of water washing - oxidation acidolysis - stepwise extraction to comprehensively recover zinc, nickel, cadmium, copper, and chlorine from high - chlorine zinc slag, solving the technical bottleneck problem of applying traditional wet zinc - smelting process technology to recover zinc from high - chlorine zinc slag and discarding chlorine resources. It realizes an environmentally friendly process technology of recovering zinc and chlorine at low cost, producing ammonium chloride and zinc sulfate products, and achieving zero discharge of three wastes. At the same time, valuable metals such as lead, cadmium, and copper in the high - chlorine zinc slag are enriched and recycled again.

[0024] (2) By adopting the process provided by the present invention, compared with the traditional method, it solves the technical bottleneck problem of applying traditional wet zinc - smelting process technology to recover zinc from high - chlorine zinc slag and discarding chlorine resources, and further realizes the comprehensive utilization of resources. It realizes the low - cost recovery of zinc and chlorine, produces ammonium chloride and zinc sulfate products, and achieves environmental friendliness with zero discharge of three wastes. It has good technical advantages and market prospects.

[0025] (3) In the process of the present invention, the condensed water in steps S3 and S7 is used for water washing the high - chlorine zinc slag in step S1, realizing the recycling of distilled water and reducing water consumption. Brief Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following - described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0027] Figure 1 It is the process flow diagram for recovering zinc, nickel, cadmium, copper, and chlorine from high - chlorine zinc slag provided by the present invention;

[0028] Figure 2 It is the influence of grinding fineness on the dechlorination rate of high - chlorine zinc slag;

[0029] Figure 3 It is the influence of solid - liquid ratio on the dechlorination rate of high - chlorine zinc slag;

[0030] Figure 4 It is the influence of reaction time on the dechlorination rate of high - chlorine zinc slag;

[0031] Figure 5 It is the influence of reaction temperature on the dechlorination rate of high - chlorine zinc slag;

[0032] Figure 6 It is the influence of the addition amount of ferric chloride on the nitrogen content in ammonium chloride crystallization;

[0033] Figure 7 It is the influence of hydrogen peroxide on the nitrogen content in ammonium chloride crystallization;

[0034] Figure 8 To respond to the influence of temperature on the comprehensive recovery rate of lead;

[0035] Figure 9 To respond to the influence of weight ratio on the comprehensive recovery rate of lead;

[0036] Figure 10 To respond to the influence of sulfuric acid concentration on the comprehensive recovery rate of lead;

[0037] Figure 11 To respond to the influence of hydrogen peroxide on the comprehensive recovery rate of lead;

[0038] Figure 12 To respond to the influence of stirring time on the comprehensive recovery rate of lead;

[0039] Figure 13 To respond to the influence of reaction temperature on the comprehensive recovery rate of iron;

[0040] Figure 14 To respond to the influence of adding zinc oxide to adjust the pH value on the comprehensive recovery rate of iron;

[0041] Figure 15 To respond to the influence of stirring time on the comprehensive recovery rate of iron;

[0042] Figure 16 To respond to the influence of reaction temperature on the comprehensive recovery rates of copper, cadmium and nickel;

[0043] Figure 17 To respond to the influence of reaction temperature on the comprehensive recovery rates of copper, cadmium and nickel;

[0044] Figure 18 To respond to the influence of stirring time on the comprehensive recovery rates of copper, cadmium and nickel. Specific implementation manners

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0046] Combined with Figure 1 As shown, it is a flowchart of a process for recovering zinc, nickel, cadmium, copper and chlorine from high-chlorine zinc slag provided by the present invention. Specifically, it includes the following steps:

[0047] S1. Perform four-stage reverse water washing on the high-chlorine zinc slag, and after solid-liquid separation, obtain washing liquid and washing residue; the parameters for four-stage reverse water washing are: the washing temperature is 10-80°C, the weight ratio of water to high-chlorine zinc slag is 3-10:1, and the washing stirring time is 1-6h.

[0048] S2. Impurity removal from the washing liquid obtained in step S1: At 10 - 80 °C, add soluble ferric chloride in an amount 2 - 15 times the molar amount of arsenic in the washing liquid, stir for 0.5 - 2 h, then add hydrogen peroxide in an amount 2 - 5 times the total molar amount of iron in the washing liquid, stir for 0.5 - 2 h, add ammonia water with a concentration of 20 wt% to adjust the pH value to 5.0 - 8.0, stir for 0.5 - 2 h, filter to obtain impurity removal residue and impurity removal liquid. Mix the impurity removal residue with the washing residue obtained in step S1 to obtain a washing mixed residue. Specifically, when the pH value is adjusted to 7.5, a precipitate is formed and filtered to obtain an ammonium chloride solution.

[0049] S3. Concentration and crystallization of the impurity removal liquid: Distill and concentrate the purified liquid obtained in step S2 to obtain ammonium chloride products. The water vapor is cooled to obtain condensed water and used for washing the high-chlorine zinc slag in step S1.

[0050] S4. Leaching the washing mixed residue obtained in step S2: At 10 - 80 °C, mix a sulfuric acid solution with a concentration of 20 - 98 wt% and the washing mixed residue at a weight ratio of 2 - 10:1, stir in a stirrer, add hydrogen peroxide with a weight of 1% - 8% of the washing mixed residue during the stirring process, stir for 1 - 6 h, then perform solid-liquid separation to obtain a leaching solution and lead sulfate slag.

[0051] S5. Neutralization and arsenic-iron removal from the leaching solution obtained in step S4: At 10 - 80 °C and under stirring, add zinc oxide powder to the leaching solution, adjust the pH value of the acidolysis solution to 2.0 - 5.5, continue to stir for 0.5 - 2 h, then filter to obtain arsenic-iron slag and iron-removed liquid.

[0052] S6. Displacement for copper, cadmium, and nickel removal: At 10 - 80 °C and under stirring, add activated zinc powder or nickel collector in an amount 1 - 4 times the molar amounts of copper, cadmium, and nickel in the iron-removed liquid, stir for 0.5 - 3 h, then displace copper, cadmium, and nickel successively to obtain a copper-cadmium-nickel-removed liquid at the same time.

[0053] S7. Concentration and crystallization of the copper-cadmium-nickel-removed liquid: Distill and concentrate the copper-cadmium-nickel-removed liquid in step S6 to obtain zinc sulfate products. The water vapor is cooled to obtain condensed water and used for washing the high-chlorine zinc slag in step S1.

[0054] In this embodiment, the process technical principle is as follows:

[0055] (1) For the part of dechlorination and co-production of ammonium chloride: Wash the high-chlorine zinc slag with appropriate particle size at a suitable temperature. Utilize the fact that lead is insoluble in water, hydrogen peroxide, and ammonia, and iron ions react with arsenic to form iron arsenate precipitate. Iron, zinc, cadmium, copper, and nickel will form hydroxide precipitates under alkaline conditions, so that valuable metals such as lead, iron, and zinc are separated from chlorine, and finally ammonium chloride remains. After distillation and condensation, it crystallizes out.

[0056] Pb 2++2OH - =Pb(OH)2↓;

[0057] Fe 3+ +AsO3 3- =FeAsO3↓;

[0058] Cu 2+ +2OH - =Cu(OH)2↓;

[0059] Fe 3+ +3OH - =Fe(OH)3↓;

[0060] Cd 2+ +2OH - =Cd(OH)2↓;

[0061] Zn 2+ +2OH - =Zn(OH)2↓;

[0062] Ni 2+ +2OH - =Ni(OH)2↓.

[0063] (2) Preparation of zinc sulfate: The washed residue and impurity-removed residue of high-chloride zinc slag are added to hydrogen peroxide and sulfuric acid for leaching. Lead is separated and removed by taking advantage of the fact that lead is insoluble in water, hydrogen peroxide, and sulfuric acid, while sulfuric acid can dissolve most metals. Hydrogen peroxide is added to activate the substances in the solution, oxidizing the divalent iron ions to trivalent iron ions. Zinc oxide powder is then added and the pH value is adjusted to form an arsenic iron slag precipitation to separate and remove iron. Taking advantage of the different chemical properties of copper, cadmium, and nickel, activated zinc powder is added to displace copper first, then cadmium, and finally nickel collector is added to displace nickel. The remaining zinc sulfate is crystallized after distillation and condensation.

[0064] Pb 2+ +SO4 2- =PbSO4↓;

[0065] 2Fe 2+ +H2O2+2H + =2H2O+2Fe 3+ ;

[0066] 2Fe 3+ +AsO3 3- +ZnO+SO4 2- +2H + =FeAsO3↓+H2O+ZnSO4;

[0067] Ni 2+ +3Zn+3SO4 2- +Cu2+ +Cd 2+ = Cu + Cd + Ni + 3ZnSO4。

[0068] When implementing this process, experiments need to be carried out to verify the process effect and determine relevant process parameters. The experimental raw materials include: high-chlorine zinc slag, hydrogen peroxide, sulfuric acid, ammonia water, ferric chloride, zinc oxide, zinc powder, and ion masking agent, all of which are of analytical purity or industrial grade.

[0069] The experimental instruments mainly include: constant temperature shaking water bath oscillator COS-110X50; centrifuge TDZ5-WS; storage tank, stirring reaction barrel; reaction kettle; blast drying oven; atomic absorption spectrophotometer GGX-600; polarograph.

[0070] Before performing step S1, first analyze the material characteristics of the high-chlorine zinc slag, analyze the components in the high-chlorine zinc slag, and determine the elements with recycling value in the high-chlorine zinc slag.

[0071] Specifically, the analysis method is as follows: First, vacuum dry the high-chlorine slag raw material at 105 °C until it reaches a constant weight, and then put it into a ball mill and crush it to a particle size where 80% or more is 200 mesh; perform chemical titration analysis, main chemical element content analysis, and phase analysis on the crushed high-chlorine zinc slag respectively. The results are shown in the following table:

[0072]

[0073] As can be seen from the above table, the main elements in the high-chlorine slag raw material are zinc, lead, and chlorine, and also contain a small amount of copper, iron, arsenic, cadmium, and nickel, etc.

[0074] I. Analysis of the dechlorination rate test of high-chlorine zinc slag

[0075] Water washing is based on the characteristics that most of the zinc chloride and other chlorides in the raw material are soluble in water, while zinc oxide is insoluble in water. Wash with water to make the chloride ions enter the solution and separate from the insoluble zinc oxide by filtration. Before performing step S1, it is necessary to measure the dechlorination rate of the water washing of the high-chlorine zinc slag. The measurement method is as follows: Heat it to a certain temperature in a water bath, then slowly add a certain mass of high-chlorine zinc slag and start timing; the stirring intensity should be such that the high-chlorine zinc slag can be stirred into the solution without precipitation; after stirring for the specified time, take out the beaker from the water bath, filter the slurry, and rinse it with a certain amount of water; dry the filter residue and weigh it and measure the chlorine mass fraction in it, and calculate the chlorine leaching rate, that is, the dechlorination rate, according to the measurement results.

[0076] 1.1 Influence of grinding fineness on the dechlorination rate of high-chlorine zinc slag

[0077] Grinding fineness condition test: When the solid-liquid ratio is 10:1, the reaction time is 1 hour, and the reaction temperature is 60 °C, the test results are shown in Figure 2。With the increase in the grinding fineness of the high-chlorine zinc slag raw material, the dechlorination rate shows an upward trend; however, after the grinding fineness reaches 80 mesh, the dechlorination efficiency is in a basically stable state. At this time, the dechlorination rate is 97.63%. This shows that the grinding fineness has a significant impact on the dechlorination rate of high-chlorine zinc slag. If the particle size is too coarse, the high-chlorine zinc slag fails to achieve effective monomer dissociation.

[0078] 1.2 Influence of solid-liquid ratio on the dechlorination rate of high-chlorine zinc slag

[0079] Solid-liquid ratio condition test: When the grinding fineness is 80μm, the reaction time is 1 hour, and the reaction temperature is 60°C, the test results are shown in Figure 3 。With the increase in the solid-liquid ratio, the dechlorination rate first rises rapidly and then the increase amplitude decreases. In this test, when the solid-liquid ratio is 10:1, the dechlorination rate has reached 97.73%, effectively removing chloride ions.

[0080] 1.3 Influence of reaction time on the dechlorination rate of high-chlorine zinc slag

[0081] Reaction time condition test: When the grinding fineness is 80μm, the solid-liquid ratio is 10:1, and the reaction temperature is 60°C, the test results are shown in Figure 4 。From Figure 4 it can be seen that the dechlorination rate first rises rapidly and then tends to be stable. When the reaction time is 80 minutes, a good dechlorination state can be achieved, which is basically consistent with the best reaction time situation reported in the relevant research on washing zinc slag with water. With the increase in reaction time, the increase is not significant.

[0082] 1.4 Influence of reaction temperature on the dechlorination rate of high-chlorine zinc slag

[0083] Reaction time condition test: When the grinding fineness is 80μm, the solid-liquid ratio is 10:1, and the reaction time is 1 hour, the test results are shown in Figure 5 。From Figure 5 it can be seen that the dechlorination rate rises and then tends to be stable, which is basically consistent with the change situation of the dechlorination rate when Sun Hongyan used sodium carbonate alkali washing to remove fluorine and chlorine from high-lead zinc oxide fumes. When the reaction temperature is 60°C, the removal of chloride ions can reach more than 98.21%.

[0084] In summary, for the four-stage reverse water washing of high-chlorine zinc slag, when the grinding fineness is 80μm, the water washing temperature is 60°C, the weight ratio of water to solid is 10:1, and the water washing stirring time is 80 minutes, more than 98% of the chloride ions in the high-chlorine zinc slag can be removed and enter the washing liquid.

[0085] II. Analysis of ammonium chloride solution purification test

[0086] In the washing solution after the high-chlorine zinc slag is fully washed with water to remove chlorine, there are still impurities such as arsenic, iron, zinc, cadmium, copper, and nickel. To effectively remove the above impurities, under suitable conditions, iron ions react with arsenic to form iron arsenate precipitate to remove arsenic. After adding ammonium chloride, various hydroxide precipitates will be generated under alkaline conditions, separating valuable metals such as lead, iron, and zinc from chlorine, and finally leaving ammonium chloride, which crystallizes out after distillation and condensation. In the experiment, the comprehensive chlorine recovery rate = (chlorine content in ammonium chloride crystals - chlorine content in added ferric chloride) / chlorine content in high-chlorine zinc slag

[0087] 2.1 Ferric chloride addition amount

[0088] The ferric chloride addition amount was for 5 conditional tests under the condition of adding ferric chloride solution with 2 - 10 times the molar amount of arsenic. The hydrogen peroxide addition amount was 4 times the total molar amount of iron ions. After adding ammonia water, the pH of the system was adjusted to 7.5. The test results are shown in Figure 6 . From Figure 6 it can be seen that as the ferric chloride addition amount increases, iron arsenate precipitate is formed, arsenic in the solution is eliminated, and the nitrogen content in ammonium chloride crystals is increased. When the addition amount is 5 times the molar amount of arsenic, it has tended to be stable. As the addition amount increases, the overall product weight increases, resulting in a decrease in the nitrogen content in ammonium chloride crystals.

[0089] 2.2 Hydrogen peroxide addition amount

[0090] The hydrogen peroxide addition amount was for 5 conditional tests under the condition of adding ammonium bicarbonate solution with 2 - 6 times the total molar amount of iron ions. The ferric chloride addition amount was for adding ferric chloride solution with 3 times the molar amount of arsenic. After adding ammonia water, the pH of the system was adjusted to 7.5. The test results are shown in Figure 7 . From Figure 7 it can be seen that as the carbon hydrogen peroxide addition amount increases, iron arsenate precipitate is fully generated. The excess hydrogen peroxide activates the subsequent process. When the addition amount is 4 times the total molar amount of iron ions, it has tended to be stable. As the addition amount increases, the overall product weight increases, resulting in a decrease in the nitrogen content in ammonium chloride crystals.

[0091] 2.3 Influence of ammonia water addition amount on the quality of ammonium chloride

[0092] The above washing solution with basically complete dechlorination was passed through ammonia water for testing. It was found that when the ammonia water addition amount was too low and the pH value in the water body did not reach about 7.5, iron hydroxide, zinc hydroxide, copper hydroxide, and cadmium hydroxide precipitates could not be generated to achieve impurity removal. When the ammonia water was slightly added too much and the pH value exceeded 8, zinc had dissolved in ammonia water to form zinc ammonia complex ions, affecting the subsequent tests.

[0093] Zn 2 ++4NH 3 .H2O=(Zn(NH3) 4 )2 ++4H2O

[0094] After ammonia is added, the solution only needs to be adjusted to a pH of about 7.5 to form a precipitate and filter to obtain an ammonium chloride solution. Finally, the ammonium chloride product is obtained through underpressure distillation, condensation, and crystallization. Under the above optimal test conditions, the purified ammonium chloride solution is subjected to underpressure distillation, condensation, and crystallization to obtain ammonium chloride powder. The ammonium chloride powder is calculated according to the calculation method of chlorine comprehensive recovery rate = (chlorine content in ammonium chloride crystallization - chlorine content in added ferric chloride) / chlorine content in high-chlorine zinc slag. The comprehensive recovery rate of chlorine in the high-chlorine zinc slag is 96.05%.

[0095] In summary, when the high-chloride zinc slag is ground to a fineness of 80μm, a solid-liquid ratio of 10:1, a reaction time of 1 hour, and a reaction temperature of 60°C, the dechlorination rate of the high-chloride zinc slag reaches 98%, and the chloride ions are effectively dissolved in the water wash. Adding soluble ferric chloride at 5 times the molar amount of arsenic in the water wash, after thorough stirring, and then adding hydrogen peroxide at 4 times the total molar amount of iron in the water wash can effectively remove arsenic from the aqueous solution. By adding ammonia water to the solution pH of 7.5, a precipitate can be formed, removing impurities such as zinc, iron, copper, and cadmium from the water wash. Finally, a purified ammonium chloride solution is obtained. After vacuum distillation, condensation, and crystallization, and after component analysis, ammonium chloride crystals are obtained. The comprehensive recovery rate of chlorine achieved by calculation is 96.05%.

[0096] After mixing the washed slag with the impurity-removed slag, an appropriate amount of sulfuric acid solution is added at a suitable temperature and stirred. During the stirring process, an appropriate amount of hydrogen peroxide is added and stirred to separate the solid and liquid, producing a leachate and lead slag. The resulting lead slag is then used for lead leaching and resource recovery. Zinc oxide powder is added to the leachate at a suitable temperature, adjusted to an appropriate pH, and stirred for a period of time before filtering to produce a deironing solution and arsenic-iron slag. The arsenic-iron slag can be processed in a rotary kiln for iron leaching and resource recovery. To the remaining deironing solution, a certain amount of activated zinc powder is added at a suitable temperature and under sufficient stirring to displace sponge copper, then sponge cadmium. Finally, a nickel collector is added to displace nickel. This process achieves the leaching and resource recovery of copper, cadmium, and nickel, respectively. The remaining solution, which only contains zinc sulfate, is then distilled and concentrated to produce the zinc sulfate product. The water vapor is cooled to produce condensed water. Because zinc oxide and activated zinc powder are added successively in the above process, the zinc content added in the above two processes must be deducted for calculation. The specific calculation formula is zinc comprehensive recovery rate = (zinc content of zinc sulfate crystals - zinc content added by zinc oxide - zinc content of activated zinc added to replace the corresponding molar number of copper, cadmium and nickel) / zinc content of high-chloride zinc slag.

[0097] 3. Experimental analysis of comprehensive lead recovery rate in high-chloride zinc slag

[0098] Utilize the property that lead is insoluble in water, hydrogen peroxide, and sulfuric acid and forms stable lead sulfate precipitate with sulfate ions. At an appropriate temperature, first add an appropriate amount of sulfuric acid to cause lead to react with sulfate ions to produce lead sulfate precipitate, and then add a certain amount of hydrogen peroxide to fully activate various impurities in the slag and dissolve them into the solution, thereby improving the purity of the lead sulfate precipitate. Based on the lead content in the formed lead sulfate precipitate, the leaching rate and comprehensive recovery rate of lead are obtained.

[0099] 3.1 Influence of reaction temperature on the comprehensive recovery rate of lead

[0100] Reaction temperature condition test: Mix a 60wt% sulfuric acid solution and washed mixed slag according to a weight ratio of 4:1, stir in a stirrer, add hydrogen peroxide with a weight of 2% of the washed mixed slag during the stirring process, and after stirring for 2 h, perform solid-liquid separation. The test results are shown in Figure 8 . From Figure 8 It can be seen that due to the property that lead is extremely insoluble in water, sulfuric acid, and hydrogen peroxide, the comprehensive recovery rate of lead basically does not change much. At the initial 10°C, the comprehensive recovery rate has reached 93.56%. After entering 30°C, the comprehensive recovery of more than 98% has basically been achieved, and it remains basically unchanged subsequently.

[0101] 3.2 Influence of weight ratio on the comprehensive recovery rate of lead

[0102] Weight ratio condition test: At 30°C, mix a 60wt% sulfuric acid solution and washed mixed slag, stir in a stirrer, add hydrogen peroxide with a weight of 2% of the washed mixed slag during the stirring process, and after stirring for 2 h, perform solid-liquid separation. The test results are shown in Figure 9 . From Figure 9 It can be seen that due to the property that lead is extremely insoluble in water, sulfuric acid, and hydrogen peroxide, the comprehensive recovery rate of lead can actually reach 83.56% in its initial state. After the weight ratio is increased to 4:1, effective and comprehensive lead recovery has been achieved.

[0103] 3.3 Influence of sulfuric acid concentration on the comprehensive recovery rate of lead

[0104] Sulfuric acid concentration condition test: At 30°C, mix a sulfuric acid solution with a concentration of 20 - 98wt% and washed mixed slag according to a weight ratio of 4:1, stir in a stirrer, add hydrogen peroxide with a weight of 2% of the washed mixed slag during the stirring process, and stir for 2 h. The test results are shown in Figure 10 . From Figure 10 It can be seen that when using a 60wt% sulfuric acid solution, the comprehensive recovery rate of lead can reach more than 98%.

[0105] 3.4 Influence of hydrogen peroxide on the comprehensive recovery rate of lead

[0106] Hydrogen peroxide condition test: At 30°C, mix a sulfuric acid solution with a concentration of 60 wt% and the washed mixed residue in a weight ratio of 4:1, stir in a stirrer, add hydrogen peroxide with a weight of 1% - 8% of the washed mixed residue during stirring, and stir for 2 h. The test results are shown in Figure 11 . From Figure 11 it can be seen that when the addition amount of hydrogen peroxide reaches 2% of the weight of the washed mixed residue, all substances can be fully activated and enter the solution.

[0107] 3.5 Effect of stirring time on the comprehensive recovery rate of lead

[0108] Stirring time condition test: At 30°C, mix a sulfuric acid solution with a concentration of 60 wt% and the washed mixed residue in a weight ratio of 4:1, stir in a stirrer, add hydrogen peroxide with a weight of 2% of the washed mixed residue during stirring, and stir for 1 - 5 h. The test results are shown in Figure 12 . From Figure 12 it can be seen that it is necessary to stir for at least [X] hours to fully precipitate lead sulfate and achieve effective separation.

[0109] In summary, from the above condition tests, it can be seen that: at 30°C, mix a sulfuric acid solution with a concentration of 60 wt% and the washed mixed residue in a weight ratio of 4:1, stir in a stirrer, add hydrogen peroxide with a weight of 2% of the washed mixed residue during stirring, and stir for 3 h, which can achieve effective leaching of lead. After obtaining lead sulfate and calculating, the comprehensive recovery rate of lead is above 98%.

[0110] IV. Experimental analysis of the comprehensive recovery rate of iron in high-chlorine zinc slag

[0111] In the leaching solution, due to the addition of hydrogen peroxide, ferrous ions in the solution are oxidized to ferric ions. After adding zinc oxide powder and adjusting the appropriate pH value, arsenic-iron slag precipitation can be formed for iron separation. After realizing the leaching of iron and calculating based on the iron content in the arsenic-iron slag, the iron leaching rate and comprehensive recovery rate can be obtained.

[0112] 4.1 Effect of reaction temperature on the comprehensive recovery rate of iron

[0113] Reaction temperature condition test: Under 5 conditions of 10 - 80°C and stirring state, add zinc oxide powder to the leaching solution, adjust the pH value of the acidolysis solution to 4, and continue stirring for 1 h. The test results are shown in Figure 13 . From Figure 13 it can be seen that the reaction temperature has little effect on the formation of arsenic-iron slag, and the comprehensive recovery of iron above 95% can be basically achieved.

[0114] 4.2 Effect of adding zinc oxide to adjust pH value on the comprehensive recovery rate of iron

[0115] Experiment on adjusting pH conditions by adding zinc oxide: At 10 °C with stirring, zinc oxide powder was added to the leaching solution. After adjusting the pH value of the acidolysis solution to 2.0 - 6 conditions, stirring was continued for 1 h. The test results are shown in Figure 14 . From Figure 14 it can be seen that after adding zinc oxide to adjust the pH value of the system to 4 or above, the comprehensive iron recovery rate can reach 95.88%. After the pH value of the system further increases, the comprehensive iron recovery rate slightly decreases.

[0116] 4.3 Influence of stirring time on comprehensive iron recovery rate

[0117] Experiment on stirring time conditions: At 10 °C with stirring, zinc oxide powder was added to the leaching solution. After adjusting the pH value of the acidolysis solution to 4, stirring was continued for 0.5 - 2.5 h. The test results are shown in Figure 15 . From Figure 15 it can be seen that after stirring for 1 hour, sufficient reaction can be achieved, and the comprehensive recovery of iron above 95% can be realized.

[0118] From the above condition experiments, it can be seen that: at any temperature and with stirring, zinc oxide powder was added to the leaching solution. After adjusting the pH value of the acidolysis solution to 4 and continuing to stir for 1 h, filtration was carried out to obtain arsenic-iron slag, and the leaching and comprehensive recovery rate of iron above 95% can be achieved.

[0119] V. Experimental analysis of comprehensive recovery rates of copper, cadmium, and nickel in high-chlorine zinc slag

[0120] Utilizing the different chemical properties of copper, cadmium, and nickel, after adding activated zinc powder, copper will be displaced first, then cadmium, and finally nickel collector is added to displace nickel. Whether each substance is completely displaced is obtained by calculation based on the component content of this type of metal in high-chlorine zinc slag. The displacement process of each metal is carried out in different reaction kettles.

[0121] 5.1 Influence of reaction temperature on comprehensive recovery rates of copper, cadmium, and nickel

[0122] Experiment on reaction temperature conditions: At 10 - 80 °C with 5 condition experiments and stirring, activated zinc powder was added according to 1.5 times the molar amount of copper and 1 times the molar amount of cadmium in the iron-removed solution; nickel collector was added according to 2 times the molar amount of nickel. After stirring for 2 h, copper, cadmium, and nickel were displaced successively. The test results are shown in Figure 16 . From Figure 16 it can be seen that after the reaction temperature reaches 50 °C or above, the comprehensive recovery of copper, cadmium, and nickel above 90% can basically be achieved.

[0123] 5.2 Influence of addition of activated zinc powder or nickel collector on comprehensive recovery rates of copper, cadmium, or nickel

[0124] Reaction temperature condition test: At 50°C and under stirring, activated zinc powder is added in an amount of 1 to 4 times the molar amount of copper and cadmium in the iron-removing solution; a nickel collector is added in an amount of 1 to 4 times the molar amount of nickel. After stirring for 2 h, copper, cadmium, and nickel are displaced successively. The test results are shown in Figure 17 . It can be seen from Figure 17 that the optimal addition multiple of activated zinc for copper displacement is 1.5 times the molar amount of copper, the optimal addition multiple of activated zinc for cadmium displacement is 1 time the molar amount of cadmium, and the optimal multiple of the nickel collector for nickel displacement is 2 times the molar amount of nickel.

[0125] 5.3 Influence of stirring time on the comprehensive recovery rates of copper, cadmium, and nickel

[0126] Stirring time condition test: At 50°C and under stirring, activated zinc powder is added in an amount of 1.5 times the molar amount of copper and 1 time the molar amount of cadmium in the iron-removing solution; a nickel collector is added in an amount of 2 times the molar amount of nickel. After stirring for 0.5 - 3 h, copper, cadmium, and nickel are displaced successively. The test results are shown in Figure 18 . It can be seen from Figure 18 that after 2 hours of stirring, sufficient reaction can be achieved to effectively displace copper, cadmium, and nickel, and the comprehensive recovery rates of copper, cadmium, and nickel reach over 95%, 92%, and 90% respectively.

[0127] From the above condition tests, it can be seen that at 50°C and under stirring, activated zinc powder is added in an amount of 1.5 times the molar amount of copper and 1 time the molar amount of cadmium in the iron-removing solution; a nickel collector is added in an amount of 2 times the molar amount of nickel. After stirring for 2 h, the comprehensive recovery rates of copper, cadmium, and nickel displaced successively reach over 95%, 92%, and 90% respectively.

[0128] In summary, for the washed mixed slag, at 30°C, a sulfuric acid solution with a concentration of 60 wt% is mixed with the washed mixed slag at a weight ratio of 4:1, stirred in a stirrer, and 2% of hydrogen peroxide by weight of the washed mixed slag is added during the stirring process. After stirring for 3 h, effective leaching of lead can be achieved to obtain lead sulfate. Zinc oxide powder is added to the leachate, and after adjusting the pH value of the acidolysis solution to 4, stirring is continued for 1 h and then filtered to obtain arsenic-iron slag, which can achieve the leaching and separation of iron. At 50°C and under stirring, activated zinc powder is added in an amount of 1.5 times the molar amount of copper and 1 time the molar amount of cadmium in the iron-removing solution; a nickel collector is added in an amount of 2 times the molar amount of nickel. After stirring for 2 h, copper, cadmium, and nickel will be displaced successively to achieve the leaching and separation of copper, cadmium, and nickel. Finally, the remaining solution is distilled and concentrated to obtain zinc sulfate products, achieving the comprehensive recovery of zinc. In the above separation processes, the leaching and separation of iron, copper, cadmium, and nickel are achieved, and the comprehensive recovery rates reach 95%, 95%, 92%, and over 90% respectively. For the finally crystallized zinc sulfate, the calculated comprehensive recovery rate is 92.63%.

[0129] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made under the inventive concept of the present invention by using the content of the specification and drawings of the present invention, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag, characterized in that, It includes the following steps: S1. Perform four-stage reverse water washing on the high-chlorine zinc slag, and after solid-liquid separation, obtain the washing liquid and the washing slag; S2. Remove impurities from the washing liquid obtained in step S1, filter to obtain the impurity-removing slag and the impurity-removing liquid, mix the impurity-removing slag with the washing slag obtained in step S1 to obtain the washed mixed slag; S3. Concentrate and crystallize the impurity-removing liquid: Distill and concentrate the purified liquid obtained in step S2 to obtain ammonium chloride products, and the water vapor is cooled to obtain condensed water and used for washing the high-chlorine zinc slag in step S1; S4. Leach the washed mixed slag obtained in step S2: Mix the sulfuric acid solution with the washed mixed slag, stir in a stirrer, add hydrogen peroxide during the stirring process, and after stirring, perform solid-liquid separation to obtain the leaching liquid and lead sulfate slag; S5. Neutralize and remove arsenic and iron from the leaching liquid obtained in step S4: Add zinc oxide powder to the leaching liquid, adjust the pH value, stir and filter to obtain arsenic-iron slag and iron-removed liquid; S6. Replace and remove copper, cadmium, and nickel: Add activated zinc powder or nickel collector to the iron-removed liquid obtained in step S5, and successively replace copper, cadmium, and nickel, and at the same time obtain the copper-cadmium-nickel-removed liquid; S7. Concentrate and crystallize the copper-cadmium-nickel-removed liquid: Distill and concentrate the copper-cadmium-nickel-removed liquid in step S6 to obtain zinc sulfate products, and the water vapor is cooled to obtain condensed water and used for washing the high-chlorine zinc slag in step S1.

2. The process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag as claimed in claim 1, wherein: In the said step S1, the parameters of the four-stage reverse water washing are: the water washing temperature is 10 - 80 °C, the weight ratio of water to the high-chlorine zinc slag is 3 - 10:1, and the water washing stirring time is 1 - 6 h.

3. The process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag as described in claim 1, characterized in that: Before performing step S1, first analyze the material characteristics of the high-chlorine zinc slag, analyze the components in the high-chlorine zinc slag, and determine the elements with recycling value in the high-chlorine zinc slag; the analysis method is: first vacuum dry the high-chlorine slag raw material at 105 °C until constant weight, and then put it into a ball mill to crush it to a particle size where 80% or more is 200 mesh; perform chemical titration analysis, main chemical element content analysis, and phase analysis on the crushed high-chlorine zinc slag respectively.

4. The process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag as claimed in claim 1, characterized in that: The method for removing impurities from the washing liquid in the said step S2 is: at 10 - 80 °C, add soluble ferric chloride in an amount of 2 - 15 times the molar amount of arsenic in the washing liquid, stir for 0.5 - 2 h, then add hydrogen peroxide in an amount of 2 - 5 times the total molar amount of iron in the washing liquid, stir for 0.5 - 2 h, add ammonia water with a concentration of 20 wt% to adjust the pH value to 5.0 - 8.0, stir for 0.5 - 2 h, and filter to obtain the impurity-removing slag and the impurity-removing liquid.

5. A process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag as claimed in claim 1, characterized in that: The method for leaching the washed mixed slag in the said step S4 is: at 10 - 80 °C, mix the sulfuric acid solution with a concentration of 20 - 98 wt% and the washed mixed slag at a weight ratio of 2 - 10:1, stir in a stirrer, add hydrogen peroxide with a weight of 1% - 8% of the washed mixed slag during the stirring process, stir for 1 - 6 h, and then perform solid-liquid separation to obtain the leaching liquid and lead sulfate slag.

6. The process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag as described in claim 1, characterized in that: In the said step S5, the method for neutralizing and removing arsenic and iron from the leaching liquid is: at 10 - 80 °C and under stirring, add zinc oxide powder to the leaching liquid, adjust the pH value of the acidolysis liquid to 2.0 - 5.5, continue to stir for 0.5 - 2 h, and then filter to obtain arsenic-iron slag and iron-removed liquid.

7. A process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag as claimed in claim 1, characterized in that: In the step S6, the method for replacing copper, cadmium and nickel is as follows: at 10-80 °C and under stirring, add activated zinc powder or nickel collector in an amount of 1-4 times the molar amount of copper, cadmium and nickel in the iron-removing solution, and after stirring for 0.5-3 h, successively replace copper, cadmium and nickel.

8. A process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag as claimed in claim 1, characterized in that: Before performing step S1, it is necessary to measure the dechlorination rate of the water washing of the high-chlorine zinc slag. The measurement method is as follows: heat to a certain temperature in a water bath, then slowly add a certain mass of high-chlorine zinc slag and start timing; the stirring intensity should be such that the high-chlorine zinc slag can be stirred into the solution without precipitation; after stirring for the specified time, take out the beaker from the water bath, filter the slurry, and rinse with a certain amount of water; dry and weigh the filter residue and measure the chlorine mass fraction therein, and calculate the chlorine leaching rate, that is, the dechlorination rate, according to the measurement results.

9. The process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag as claimed in claim 1, characterized in that: Before performing step S1, first grind the high-chlorine zinc slag, and at the same time measure the influence of the grinding fineness on the dechlorination rate of the high-chlorine zinc slag, and determine that the optimal grinding fineness is 80 mesh.

10. A process for recovering zinc, nickel, cadmium, copper, and chlorine from high-chlorine zinc slag as claimed in claim 4, characterized in that: In the step S2, when the pH value is adjusted to 7.5, a precipitate is formed and filtered to obtain an ammonium chloride-containing solution.

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