Method for preparing high-purity zinc sulfate from side-blown converter copper smelting smoke dust

Abstract

The invention provides a method for preparing high-purity zinc sulfate from side-blown converter copper smelting smoke dust, and relates to the technical field of smoke gas recovery, and the method comprises the following steps: S1, water leaching; s2, replacing and depositing copper; s3, neutralizing, oxidizing and removing arsenic; s4, neutralizing to remove iron, and adding a calcium hydroxide solution (20% water suspension) to obtain ferric hydroxide; s5, replacing and precipitating cadmium, adding 1.2 times of zinc powder into the neutralized liquid according to the content of cadmium, reacting for 2-3 hours at the temperature of 60-80 DEG C, and performing solid-liquid separation to obtain sponge cadmium; and S6, after cadmium removal, adding the filtrate into a concentration kettle for evaporation and concentration, feeding the prepared concentrated material into a centrifugal machine for centrifugal separation, returning the separated liquid to the concentration kettle, and carrying out flash evaporation sieving treatment on the separated solid at 180 DEG C to prepare zinc sulfate powder. The purity of the zinc sulfate product is high, and the requirements of different fields for high-quality zinc sulfate can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas recovery, and particularly to a method for preparing high-purity zinc sulfate from copper smelting dust in a side-blown furnace. Background Art

[0002] In domestic copper smelting, there are several furnace types such as flash furnaces, top-blown furnaces, bottom-blown furnaces, and side-blown furnaces. Due to the differences in furnace types, smelting processes, and raw material properties, the dust generated has complex compositions, different phases and properties. Generally, copper smelting enterprises directly return the dust to the smelting system, resulting in the enrichment of harmful components in the smelting furnace, the deterioration of the furnace condition, and the reduction of treatment capacity, and even affecting the quality of cathode copper products. Therefore, copper smelting plants generally classify and sell the dust, returning the high-copper dust to the system and selling the low-copper dust for external treatment.

[0003] There are corresponding treatment and recovery processes for the dust from flash furnaces, top-blown furnaces, and bottom-blown furnaces, but there is a lack of systematic research on the recovery of high-value metals in the dust from side-blown furnaces, especially the zinc recovery process. With the increasing shortage of resources, the resource utilization of smelting dust has become an industry consensus. By recovering valuable metals from smelting dust, not only can the resource utilization rate be improved, but also the production cost can be reduced.

[0004] The main element contents are shown in the following table ( / %)

[0005]

[0006] In summary, the background of the invention patent for a method for preparing high-purity zinc sulfate from copper smelting dust in a side-blown furnace is mainly based on the resource utilization demand of copper smelting dust and the market value of high-purity zinc sulfate. This invention not only has important economic value but also is of great significance for promoting the sustainable development of the copper smelting industry.

[0007] Generally, wet leaching processes are used for copper smelting dust, but different wet treatment processes all have certain defects and cannot prepare high-purity zinc sulfate.

[0008] The treatment process flow of a certain company's flash furnace dust is: water leaching → hydrocyclone separation → acid leaching → neutralization for arsenic and copper removal → neutralization for zinc removal → sodium sulfate enrichment. Its main defect is that valuable metals are not separated cleanly, and it is difficult to obtain high-purity products. The zinc sulfate product contains relatively high copper and arsenic, which affects the product quality.

[0009] The treatment process flow of a certain company's top-blown furnace dust is: acid leaching → electrolytic copper removal → evaporation and concentration of crude zinc sulfate → neutralization for acid and impurity removal → evaporation and concentration of refined zinc sulfate. Its main defects are low metal leaching rate, high energy consumption in two-stage evaporation and concentration, and high cadmium, arsenic, etc. content in zinc sulfate, resulting in low product quality. Summary of the Invention

[0010] In view of the above problems, the present invention provides a method for preparing high-purity zinc sulfate from the dust generated in the copper smelting process of a side-blown furnace. The zinc sulfate product of this invention has a high purity and can meet the requirements for high-quality zinc sulfate in different fields.

[0011] The technical solution adopted by the present invention to solve the above problems is as follows:

[0012] A method for preparing high-purity zinc sulfate from the dust generated in the copper smelting process of a side-blown furnace, comprising the following steps: S1. Water leaching, preferentially leaching zinc elements and metal compounds soluble in water; lead, bismuth, and antimony are not leached, generating lead-bismuth slag; S2. Copper replacement precipitation, taking a certain amount of the leaching solution, adding a reducing agent according to the copper content in the solution, and after solid-liquid separation, obtaining a sponge copper product; S3. Neutralization and oxidation for arsenic removal, adding an oxidizing agent to oxidize the iron in the solution to trivalent and arsenic to pentavalent until all the arsenic in the solution precipitates, obtaining iron arsenate slag; S4. Neutralization for iron removal, adding a calcium hydroxide solution (20% water suspension) to obtain iron hydroxide; S5. Cadmium replacement precipitation, for the neutralized liquid, adding 1.2 times the zinc powder according to the cadmium content, reacting at a temperature of 60 - 80 °C for 2 - 3 h, and performing solid-liquid separation to obtain sponge cadmium; S6. The filtrate after cadmium removal is added to a concentration kettle for evaporation concentration, the prepared concentrated material is sent to a centrifuge for centrifugal separation, the separated liquid is returned to the concentration kettle, and the separated solid is subjected to flash evaporation and sieving treatment. The flash evaporation temperature is 180 °C to obtain zinc sulfate powder.

[0013] Preferably, in step S1, the reaction time is 2 - 3 h, the liquid-solid ratio is 4:1 (ml:g), and the reaction temperature is 70 - 90 °C.

[0014] Preferably, in step S2, reduced iron powder is used to replace and recover copper, adding 1.2 times the reduced iron powder of the copper content, and reacting at 50 - 60 °C for 60 min.

[0015] Preferably, after copper precipitation, zinc oxide is added to adjust the pH between 1 and 2, and 25% hydrogen peroxide with 1.2 times the divalent iron content is added to oxidize the iron in the solution to trivalent and arsenic to pentavalent, and reacting at 60 - 80 °C for 1 - 2 h.

[0016] Preferably, in step S4, the pH is controlled between 4 and 4.5, and reacting at 60 - 80 °C for 1 - 2 h.

[0017] Preferably, in step S6, the concentration temperature is maintained at 98 °C, the filtrate after cadmium removal is stirred, and while stirring, the filtrate after cadmium removal is continuously added until the zinc concentration in the concentrated liquid reaches 200 g / l, then the addition of the filtrate after cadmium removal is stopped, and evaporation concentration continues. When the concentration of the concentrated liquid is 300 g / l, discharging starts.

[0018] Preferably, in step S1, a flue gas dust settling and collecting device is used to settle and collect the soot in the flue gas; it includes a settling device, a smoke outlet and a smoke inlet. A settling channel for the flue gas to flow through is formed inside the settling device. An atomizing nozzle is arranged inside the settling channel, and a collecting device is arranged at the bottom of the settling channel. The collecting device includes a collecting cylinder and a collecting main body. Two collecting chambers are opened on the outside of the collecting main body. The collecting main body is sealed and rotatably connected to the collecting cylinder. After the first collecting chamber collects for a predetermined time, it deflects by a predetermined angle, and the second collecting chamber is controlled to rotate to the inside to achieve continuous collection.

[0019] Preferably, a partition is arranged inside the settling device, and a settling channel with a V-shaped cross-section is formed by the partition.

[0020] Preferably, an accommodation chamber is formed inside the partition, a dislocation chamber is formed between the collecting chamber on the inner side and the collecting cylinder, and a pumping device is arranged between the dislocation chamber and the accommodation chamber to control the directional pumping of liquid. A filtering device is arranged inside the pumping device.

[0021] The beneficial effects of the present invention are as follows:

[0022] Compared with the prior art, the method adopted by the invention can ensure that the purity of zinc sulfate reaches 99.5%, exceeding the industry standard. The purity of the zinc sulfate product of the invention is relatively high, which can meet the needs of different fields for high-quality zinc sulfate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flowchart of the method of the present invention.

[0024] Figure 2 It is a three-dimensional structural schematic diagram of the flue gas dust settling and collecting device of the present invention.

[0025] Figure 3 For the present invention Figure 1 is a front view structural schematic diagram.

[0026] Figure 4 For the present invention Figure 3 is a sectional structural schematic diagram taken along the A-A direction.

[0027] Figure 5 For the present invention Figure 4 is an enlarged structural schematic diagram at position B.

[0028] In the figure: 100, settling device; 110, settling channel; 120, accommodation chamber; 121, pumping device; 130, partition; 200, smoke outlet; 300, smoke inlet; 400, collecting device; 4001, dislocation chamber; 410, collecting cylinder; 411, sealing block; 420, collecting main body; 421, electric control rotating shaft; 4201, collecting chamber. Detailed implementation mode

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Refer to the attached Figure 1 - attached Figure 5 A method for preparing high-purity zinc sulfate from copper smelting dust in a side-blowing furnace. Step 1: Water leaching. Metal compounds that are easily soluble in water, especially zinc elements, are preferentially leached. The reaction time is 2 - 3h, the liquid-solid ratio is 4:1 (ml:g), and the reaction temperature is 70 - 90°C. Among them, lead, bismuth, and antimony are not leached, and lead-bismuth slag is formed.

[0031] Step 2: Displacement and copper precipitation. Reductive iron powder is used to displace and recover copper. A certain amount of leaching solution is taken, and according to the copper content in the solution, 1.2 times the amount of reductive iron powder is added, and the reaction is carried out at 50 - 60°C for 60 minutes. After solid-liquid separation, sponge copper products are obtained.

[0032] Step 3: Neutralization, oxidation, and arsenic removal. After copper precipitation, zinc oxide is added to the solution to adjust the pH to between 1 and 2, and 25% hydrogen peroxide with 1.2 times the content of divalent iron is added to oxidize the iron in the solution to trivalent and arsenic to pentavalent. The reaction is carried out at 60 - 80°C for 1 - 2 hours until all the arsenic in the solution precipitates, and iron arsenate slag is obtained.

[0033] Step 4: Neutralization and iron removal. Calcium hydroxide solution (20% water suspension) is added to control the pH between 4 and 4.5, and the reaction is carried out at 60 - 80°C for 1 - 2 hours to obtain iron hydroxide.

[0034] Step 5: Displacement and cadmium precipitation. For the neutralized liquid, 1.2 times the amount of zinc powder is added according to the cadmium content, and the reaction is carried out at 60 - 80°C for 2 - 3 hours. After solid-liquid separation, sponge cadmium is obtained.

[0035] Step 6: The filtrate after cadmium removal is added to a concentration kettle for evaporation and concentration. The concentration temperature is maintained at 98°C, and the filtrate after cadmium removal is stirred. While stirring, the filtrate after cadmium removal is continuously added until the zinc concentration in the concentrated liquid reaches 200g / l, then the addition of the filtrate after cadmium removal is stopped, and evaporation and concentration continue. When the concentration of the concentrated liquid is 300g / l, discharging starts. The prepared concentrated material is sent to a centrifuge for centrifugal separation. The separated liquid is returned to the concentration kettle, and the separated solid is subjected to flash evaporation and sieving treatment. The flash evaporation temperature is 180°C, and zinc sulfate powder is prepared.

[0036] 1. Water leaching process: Since the dust itself has weak acidity and there are differences in the solubility of metal elements and their compounds, zinc elements are more easily leached. By precisely controlling the water leaching time (2 - 3 hours), liquid-solid ratio (4:1, ml:g), and reaction temperature (70 - 90°C), it is ensured that metal compounds that are easily soluble in water, especially zinc elements, can be preferentially and efficiently leached. This step lays a solid foundation for the subsequent extraction and separation of metals.

[0037] 2. Preparation of sponge copper in the iron powder replacement process: Fe + CuSO 4 →FeSO 4 + Cu↓. Use reduced iron powder to replace and recover copper. By precise calculation and adding an appropriate amount of reduced iron powder (adding reduced iron powder with a content 1.2 times that of copper in the solution), efficient recovery of copper is achieved within a reaction time of 60 minutes. This step not only improves the recovery rate of copper but also reduces production costs.

[0038] 3. Neutralization, oxidation, and arsenic removal process:

[0039] ZnO + H 2 SO 4 →ZnSO 4 + H 2 O

[0040] 2FeSO 4 + H 3 AsO 3 + H 2 O 2 + H 2 SO 4 →Fe 2 (SO 4 ) 3 + H3AsO 4 + 2H 2 O

[0041] Fe 2 (SO4) 3 + 2H3AsO 4 →2FeAsO 4 ↓ + 3H 2 SO 4

[0042] By adding zinc oxide and hydrogen peroxide for treatment and controlling the pH value of the solution at 1 - 2, arsenic precipitation is achieved, and iron arsenate slag is generated; this step effectively removes harmful impurities in the solution and improves the purity of subsequent metal extraction.

[0043] 4. Neutralization and iron removal: Fe 2 (SO4) 3 + 3Ca(OH) 2 =2Fe(OH) 3 ↓ + 3CaSO 4 ↓

[0044] Calcium hydroxide (Ca(OH) 2 ) has strong alkalinity and can undergo a neutralization reaction with acidic substances in the wastewater, increasing the pH value of the solution.

[0045] At an appropriate pH value, iron ions (such as Fe 3+ ) in the wastewater will react with hydroxide ions (OH - ) to form iron hydroxide (Fe(OH) 3 ) precipitate; this step effectively removes harmful impurities in the solution and improves the purity of subsequent metal extraction.

[0046] 5. Preparation of sponge cadmium in the zinc powder replacement process: Zn + CdSO 4 →ZnSO 4 + Cd↓ Add 1.2 times of zinc powder according to the cadmium content, and through a reaction time of 2 - 3 hours, achieve efficient extraction of cadmium; this step not only improves the recovery rate of cadmium, but also ensures the purity and quality of the extracted cadmium.

[0047] 6. Evaporation and concentration technology: Continuously stir and add the filtrate after cadmium removal until the addition stops when the zinc concentration in the concentrated solution reaches 200 g / l. This step ensures that the zinc ion concentration in the concentrated solution reaches an appropriate level, providing a good basis for subsequent centrifugal separation and flash evaporation treatment; when the concentration of the concentrated solution further increases to 300 g / l, start discharging. The selection of this concentration ensures the quality and yield of the final product.

[0048] Currently, the industry standard requires the purity of high-purity zinc sulfate to exceed 99%, while the method adopted in the present invention can ensure that the purity of zinc sulfate reaches 99.5%, exceeding the industry standard.

[0049] By precisely controlling the conditions (time, liquid-solid ratio, reaction temperature) of the water leaching step, the present invention can efficiently leach metal compounds that are easily soluble in water, especially zinc element, providing a high-concentration metal solution for subsequent steps.

[0050] In the replacement and copper precipitation step, copper is recovered by using reduced iron powder for replacement, achieving efficient recovery of copper and obtaining a sponge copper product with relatively high purity.

[0051] In the neutralization, oxidation and arsenic-iron removal step, by adding hydrogen peroxide and controlling the pH value, sequential precipitation of arsenic and iron is achieved, effectively removing harmful impurities in the solution.

[0052] Adding zinc powder to the neutralized liquid can efficiently extract cadmium to obtain sponge cadmium. In the evaporation and concentration step, the present invention evaporates and concentrates the pure zinc sulfate solution. When the total zinc content in the solution reaches 200 g / L, cooling crystallization is carried out. By precisely controlling the cooling rate and time, zinc sulfate crystals are fully crystallized and precipitated, thus obtaining a high-quality zinc sulfate product.

[0053] The purity of the zinc sulfate product is relatively high, which can meet the requirements for high-quality zinc sulfate in different fields; the comparison chart of the standard content and the content of the present invention of zinc sulfate is as follows:

[0054] Comparison chart of the standard content of zinc sulfate and the content of the present invention.

[0055] Item Industry standard content Content of the present invention Zinc sulfate monohydrate w / % ≥ 98.0 99.5 Insoluble matter ≤ 0.020 0.010 PH (50g / L solution) ≥ 4.0 4.0 Chloride (calculated as Cl) w / % ≤ 0.20 0.15 Lead (Pb) w / % ≤ 0.001 0.001 Iron (Fe) w / % ≤ 0.005 0.001 Manganese (Mn) w / % ≤ 0.01 0.005 Cadmium (Cd) w / % ≤ 0.001 0.001 Chromium (Cr) w / % ≤ 0.0005 0.0003

[0056] Refer to the appendix Figure 1 - 5 Figure 1 - 5 , the present invention also uses a flue gas dust settling and collecting device for settling the soot in the flue gas and efficiently collecting and quickly water-soaking the settled soot; it includes a settling device 100. An outlet 200 is provided at the upper end of the settling device 100, and an inlet 300 is provided on the side wall. A partition 130 is fixed inside the settling device 100. The partition 130 forms a settling channel 110 inside the settling device 100. Through the settling channel 110, the inlet 300 and the outlet 200 can be connected to allow the flue gas containing soot to flow in a directed manner.

[0057] The cross-section of the settling channel 110 here is V-shaped, and the flue gas can bend and flow inside the settling channel 110. At the same time, there is also a spraying device inside the settling channel 110. The atomized water vapor sprayed inside the settling channel 110 can settle the soot in the flue gas. While purifying the flue gas, the soot is settled and collected, and finally the purified flue gas is discharged from the outlet 200.

[0058] A collecting device 400 is provided at the lower end of the settling channel 110. Through the collecting device 400, the settled soot and part of the atomized water can be centrally collected. The collecting device 400 is arranged at the lowest part of the settling channel 110. Under the action of gravity, the soot and the atomized water can automatically flow towards the collecting device 400.

[0059] It should be noted that the flow of the soot and the atomized water in the settling channel 110 can be accelerated by increasing the inclination inside the settling channel 110, increasing the flow rate of the atomized water, or by setting a special scraper structure, accelerating their flow towards the collecting device 400 and improving the collection efficiency of the two.

[0060] The collecting device 400 here includes a collecting cylinder 410. A collecting main body 420 is rotatably connected inside the collecting cylinder 410. The collecting main body 420 is rotationally controlled through an electric control rotating shaft 421 in the middle. Concave collecting chambers 4201 are formed on both sides of the collecting main body 420. Through the collecting chambers 4201, the soot and the atomized water can be collected; by rotating the collecting main body 420 to different positions, different collecting chambers 4201 can be made to face the settling channel 110. By setting the above structure, after the soot is collected for a certain time, the collecting main body 420 can be rotated and switched to ensure continuous collection effect.

[0061] An arc-shaped sealing block 411 is fixed inside the collection cylinder 410. The sealing block 411 here can seal the collection main body 420 from the outside. When the collection main body 420 is relatively fixed, the collection cylinder 410 fits against the outer surface of the collection main body 420 to prevent flue gas leakage.

[0062] A high-pressure pump gas device or a cleaning device can be arranged inside the sealing block 411 to clean the gap between the sealing block 411 and the collection main body 420, preventing soot from entering the gap and ensuring the normal rotation of the collection main body 420.

[0063] The sealing block 411 here can also divert the mixed medium of soot and atomized water so that the two can flow into the collection chamber 4201 for centralized collection.

[0064] It should be noted that the collection chamber 4201 can form a larger misaligned chamber 4001 with the inside of the collection cylinder 410, and the rotation of the collection main body 420 will not be affected during the rotation process.

[0065] An accommodation chamber 120 for accommodating atomized liquid is formed inside the partition plate 130. The accommodation chamber 120 is communicated with the atomizing nozzles inside the sedimentation channel 110. The liquid in the accommodation chamber 120 can also absorb the heat in the flue gas, realizing the cooling of the flue gas and the efficient recycling of resources at the same time.

[0066] A pumping device 121 is arranged between the misaligned chamber 4001 and the accommodation chamber 120. Through the pumping device 121, the liquid in the misaligned chamber 4001 can be pumped into the accommodation chamber 120 in a directed manner to supplement the liquid in the accommodation chamber 120; it should be noted that a filtering device is arranged on the side of the pumping device 121 close to the misaligned chamber 4001 to prevent the soot settled in the misaligned chamber 4001 from being sucked into the accommodation chamber 120.

[0067] Through the above method, in the initial stage of soot sedimentation, the amount of soot and atomized water collected in the collection device 400 is small. By increasing the amount of atomized water and the water pumped by the pumping device 121, the sedimentation rate of soot can be increased, and the atomized water and soot can quickly flow into the collection device 400 for collection in a short time, realizing rapid circulation.

[0068] In the later stage of soot settlement, the amount of soot and atomized water collected in the collection device 400 is relatively large. At this time, the amount of atomized water and the water pumped by the pumping device 121 are adjusted, and the ratio between the soot and the atomized water in the smoke inlet 300 is adjusted to ensure that the ratio of the two meets the requirements, saving the consumption of atomized water, streamlining the subsequent process, and improving the processing efficiency. For example, the liquid-solid ratio between the soot and the atomized water can be controlled to be 4:1 (ml:g), which can adjust the ratio of the final soot and atomized water mixed medium in the collection device 400 to a predetermined required state, accelerating the subsequent processing.

[0069] After the soot and atomized water mixed medium is collected in the first collection chamber 4201 of the collection device 400, the collection main body 420 is controlled to rotate, and the first collection chamber 4201 rotates to the bottom position to realize the discharging of the mixed medium; another collection chamber 4201 rotates to the inside to realize the continuous collection of soot.

[0070] It should also be noted here that a transfer mechanism and a cleaning device are provided at the lower end of the collection device 400 for collecting the soot in the collection chamber 4201 and cleaning the inside of the collection chamber 4201.

[0071] A liquid level gauge and a mass detection device can be provided in the dislocation chamber 4001 to detect the liquid level height and the total mass in the collection chamber 4201, roughly estimate the ratio of the soot and the atomized water, and serve as an indication signal for controlling the rotation of the collection main body 420 to achieve automatic control.

[0072] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing high-purity zinc sulfate from copper smelting dust in a side-blown furnace, characterized in that: The steps include: S1, water leaching, zinc element and metal compounds soluble in water are leached out first, lead, bismuth and antimony are not leached out, and lead-bismuth slag is generated; S2, replace the copper precipitation, transfer a certain amount of leachate, add a reducing agent according to the copper content in the solution, and obtain a sponge copper product after solid-liquid separation; S3, neutralization oxidation dearsenification, adding an oxidant to oxidize the iron in the solution to trivalent iron and arsenic to pentavalent iron, until all the arsenic in the solution is precipitated to obtain arsenic acid iron slag; S4, neutralize and remove iron, add calcium hydroxide solution (20% aqueous suspension) to obtain iron hydroxide; S5, replace the cadmium precipitation, add 1.2 times of zinc powder according to the cadmium content in the neutralized liquid, react at a temperature of 60-80° for 2-3h, and separate the solid and liquid to obtain sponge cadmium; S6. After cadmium removal, the filtrate is added to a concentration kettle for evaporation and concentration. The obtained concentrated material is sent to a centrifuge for centrifugal separation. The separated liquid is returned to the concentration kettle. The separated solid is flash-evaporated and sieved at a flash evaporation temperature of 180° C. to obtain zinc sulfate powder.

2. The method for preparing high-purity zinc sulfate from side-blown furnace copper smelting dust according to claim 1, characterized in that: In step S1, the reaction time is 2-3 hours, the liquid-to-solid ratio is 4:1 (ml:g), and the reaction temperature is 70-90°C.

3. The method for preparing high-purity zinc sulfate from side-blown furnace copper smelting dust according to claim 1, characterized in that: In step S2, reduced iron powder is used to replace and recover copper, and reduced iron powder with a copper content of 1.2 times is added, and the reaction is carried out at 50-60° C. for 60 minutes.

4. The method for preparing high-purity zinc sulfate from side-blown furnace copper smelting dust according to claim 1, characterized in that: After copper deposition, zinc oxide is added to adjust the pH to between 1 and 2, and 25% hydrogen peroxide with 1.2 times the content of divalent iron is added to oxidize the iron in the solution to trivalent and the arsenic to pentavalent, and react at 60-80°C for 1-2 hours.

5. The method for preparing high-purity zinc sulfate from side-blown furnace copper smelting dust according to claim 1, characterized in that: In step S4, the pH is controlled between 4 and 4.5, and the reaction is carried out at 60-80° C. for 1-2 hours.

6. The method for preparing high-purity zinc sulfate from side-blown furnace copper smelting dust according to claim 1, characterized in that: In step S6, the concentration temperature is maintained at 98° C., the filtrate after cadmium removal is stirred, and the filtrate after cadmium removal is continuously added while stirring until the zinc concentration of the concentrated solution reaches 200 g / l, then the addition of the filtrate after cadmium removal is stopped, and evaporation and concentration are continued. When the concentration of the concentrated solution reaches 300 g / l, discharge is started.

7. The method for preparing high-purity zinc sulfate from side-blown furnace copper smelting dust according to claim 1, characterized in that: In step S1, a flue gas dust collection device is used to collect and settle the smoke in the smoke; the device comprises a settling device (100), a smoke outlet (200) and a smoke inlet (300); a settling channel (110) for smoke circulation is formed inside the settling device (100); an atomizing nozzle is arranged inside the settling channel (110); a collecting device (400) is arranged at the bottom of the settling channel (110); the collecting device (400) comprises a collecting barrel (410) and a collecting body (420); two collecting chambers (4201) are arranged on the outside of the collecting body (420); the collecting body (420) is sealed and rotatably connected to the collecting barrel (410); the first collecting chamber (4201) deflects to a predetermined angle after collecting for a predetermined time; and the second collecting chamber (4201) is controlled to rotate to the inside to achieve continuous collection.

8. The method for preparing high-purity zinc sulfate from side-blown furnace copper smelting dust according to claim 7, characterized in that: A partition (130) is arranged inside the sedimentation device (100), and a sedimentation channel (110) with a V-shaped cross section is formed by the partition (130).

9. The method for preparing high-purity zinc sulfate from side-blown furnace copper smelting dust according to claim 8, characterized in that: A accommodating chamber (120) is formed inside the partition (130), and an offset chamber (4001) is formed between the collecting chamber (4201) located inside and the collecting tube (410). A pumping device (121) is provided between the offset chamber (4001) and the accommodating chamber (120) for controlling directional pumping of the liquid, and a filtering device is provided inside the pumping device (121).

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