Device and method for recycling zinc powder and iron powder in wastewater of hot-dip galvanizing skin pass mill

Abstract

The invention discloses a device for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill, which comprises a micro-electrolysis reactor, a Fenton reactor and a zinc-iron sedimentation tank connected in sequence. The micro-electrolysis reactor and the Fenton reactor adopt a fluidized bed form to improve the reaction efficiency. The invention also discloses a method for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill. The method mainly includes: simultaneously separating zinc powder and iron powder from the wastewater of the temper mill and dehydrating and drying them; making the dried zinc powder and iron powder into ternary micro-electrolysis fillers; putting the ternary micro-electrolysis fillers into the device for recycling zinc powder and iron powder in the wastewater of the hot-dip galvanizing temper mill for sewage treatment to obtain flocculent sludge containing zinc and iron; dehydrating the flocculent sludge to produce a desulfurizer product. The invention conducts secondary recycling on the zinc powder and iron powder in the wastewater of the temper mill, has a low treatment cost, realizes the purpose of saving resources, reduces the impact of pollutants on the environment, and improves the environmental and economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of recovering zinc powder and iron powder, and particularly to a device for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing skin pass mill, and also to a method for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing skin pass mill. Background Art

[0002] At present, hot-dip galvanized products are widely used, and the production technology of hot-dip galvanized steel sheets in the iron and steel industry has developed rapidly. The rapid development of hot-dip galvanizing technology makes the surface quality comparable to that of cold-rolled sheets and electro-galvanized sheets.

[0003] The basic production process flow of continuous hot-dip galvanizing of strip steel is: pickling > welding > cleaning > entrance loop > annealing > hot-dip galvanizing > skin pass rolling > tension leveling > passivation > exit loop > coiling.

[0004] Skin pass rolling is an important process in hot-dip galvanizing production and plays a very important role in ensuring the quality of hot-dip galvanized products. The function of skin pass rolling is to eliminate the yield plateau of the annealed strip steel, improve the mechanical properties and flatness of the strip steel, make the strip steel surface have a certain roughness, improve the adhesion of the paint film and the surface finish, and ensure the surface quality of the sheet.

[0005] When the existing skin pass mill skins hot-dip galvanized sheets, the zinc particles or other impurities adhered to the skin pass support rolls will also be replicated onto the work rolls. As the rolling force increases, it will be more and more difficult to eliminate the zinc particles or impurities that are more tightly combined with the roll surface, resulting in skin pass bright spots and skin pass roll marks. Therefore, high-pressure demineralized water is used to wash the roll gap and roll surface in time behind the skin pass mill during skin pass rolling.

[0006] At present, the wastewater of the skin pass mill is all discharged to the sewage treatment station for treatment. The wastewater of the skin pass mill contains a certain amount of zinc powder and iron powder. If these zinc powder and iron powder are not collected and treated, it will lead to sludge accumulation in the sewage tank, increase the maintenance cost, and also have an adverse impact on the subsequent treatment. The suspended matter components in the wastewater of the skin pass mill are mainly zinc powder, iron powder and other impurities, among which the zinc content is about 50 - 60%, the iron content is 10 - 20%, and other components are 20 - 30%.

[0007] One way to recycle zinc powder from the suspended matter in the wastewater of the skin pass mill is smelting. Zinc smelting methods are divided into two major categories: pyrometallurgical zinc smelting and hydrometallurgical zinc smelting. Among them, hydrometallurgical zinc smelting includes acid method zinc smelting and alkali method zinc smelting. At present, the main zinc smelting method in the world is hydrometallurgical zinc smelting, and more than 80% of the primary zinc ingots are produced by hydrometallurgical zinc smelting methods.

[0008] There are many problems in directly treating zinc secondary resources with the traditional sulfuric acid - electrolytic zinc process. The zinc powder contains more iron powder and other impurities, and the process of separating these impurities in the acid leaching solution is relatively complex and difficult to control.

[0009] Although the caustic soda method has the advantages of a wide range of raw material adaptability, less leached impurities, simple purification process, high current efficiency, low electrolysis energy consumption, and low capital investment, it is more suitable for treating low-grade zinc oxide waste. The recovery cost of high-content zinc powder is relatively high, and iron powder cannot be recovered simultaneously, resulting in a waste of iron powder resources.

[0010] In the pyrometallurgical zinc smelting process, to simultaneously recover zinc powder and iron powder, among the existing technologies, the two-stage reduction method is used. First, carbon is added to reduce iron oxide, and then the reduced metallic iron is used to continue reducing zinc oxide, enabling the direct recovery of metallic zinc and the secondary resource utilization of iron. This method requires precise control of temperature and the ratio of zinc to iron, and it cannot completely recover zinc powder and iron powder.

[0011] The micro-electrolysis technology is a pretreatment technology widely used in industrial water treatment. By making waste zinc powder, iron powder, and activated carbon into micro-electrolysis fillers, it has low cost and is of great significance in "treating waste with waste". Currently, the conventional micro-electrolysis technology is binary micro-electrolysis technology, and its efficiency still needs to be improved.

[0012] In addition, recycling waste zinc powder and iron powder alone as micro-electrolysis fillers is not as valuable as recycling and re-producing zinc powder. Therefore, it is necessary to conduct secondary recycling of waste zinc powder and iron powder to increase economic benefits. Summary of the Invention

[0013] The purpose of the present invention is to solve the problems in the current technology, and provide a device for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill. In addition, a method for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill is provided. Under the condition of low cost, through secondary recycling, zinc powder and iron powder in the temper mill wastewater can be simultaneously recycled, achieving the purpose of resource conservation, reducing the environmental impact of pollutants, and improving environmental and economic benefits.

[0014] To achieve the above purpose, the solution provided by the present invention is as follows:

[0015] Device for recycling zinc powder and iron powder from wastewater of hot-dip galvanizing temper mill, including a micro-electrolysis reactor, further including a Fenton reactor and a zinc-iron sedimentation tank. A micro-electrolysis reactor water inlet is arranged at the top of the micro-electrolysis cylinder body of the micro-electrolysis reactor. The lower port of the micro-electrolysis reactor water inlet extends downward to the lower part inside the micro-electrolysis cylinder body. An annular air inlet pipe is arranged at the lower part inside the micro-electrolysis cylinder body. The annular air inlet pipe is connected to the micro-electrolysis reactor air inlet main pipe arranged on the micro-electrolysis cylinder body. A plurality of micro-electrolysis reactor air inlet branch pipes are evenly distributed on the annular air inlet pipe. The outlet direction of the micro-electrolysis reactor air inlet branch pipe forms a set angle with the diameter direction of the annular air inlet pipe where the micro-electrolysis reactor air inlet branch pipe is located; A plurality of circulating water distribution pipe branch pipes are circumferentially arranged at the lower part of the micro-electrolysis cylinder body. The water outlet of the circulating water distribution pipe branch pipe extends into the micro-electrolysis cylinder body. The water outlet direction of the circulating water distribution pipe branch pipe forms a set angle with the diameter direction of the micro-electrolysis cylinder body where the circulating water distribution pipe branch pipe is located. A ring-shaped circulating water distribution pipe main pipe is sleeved at the lower part of the micro-electrolysis cylinder body. Each circulating water distribution pipe branch pipe is connected to the circulating water distribution pipe main pipe. The water inlet port of the circulating water distribution pipe main pipe is connected to the water outlet of the circulating pump. The water inlet of the circulating pump is connected to the circulating pump water inlet at the upper part of the side wall of the micro-electrolysis cylinder body; The height of the circulating pump water inlet is lower than the height of the micro-electrolysis reactor water outlet arranged on the side wall of the micro-electrolysis cylinder body.

[0016] A Fenton reactor water inlet is arranged at the top of the Fenton reaction cylinder body of the Fenton reactor. The water outlet of the micro-electrolysis reactor is connected to the upper port of the Fenton reactor water inlet. The lower port of the Fenton reactor water inlet extends downward to the lower part inside the Fenton reaction cylinder body; An air inlet ring is arranged at the bottom inside the Fenton reaction cylinder body. The air inlet ring is connected to the Fenton reactor air inlet main pipe arranged on the Fenton reaction cylinder body. A plurality of Fenton reactor air inlet branch pipes are evenly arranged on the air inlet ring. The outlet direction of the Fenton reactor air inlet branch pipe forms a set angle with the diameter direction of the air inlet ring where the Fenton reactor air inlet branch pipe is located.

[0017] Ternary micro-electrolysis filler is put into the micro-electrolysis reactor.

[0018] As described above, a micro-electrolysis reactor conical baffle and a micro-electrolysis reactor annular baffle are arranged on the bottom surface of the micro-electrolysis cylinder body. The micro-electrolysis reactor conical baffle is located inside the inner ring of the micro-electrolysis reactor annular baffle. The area surrounded by the inner ring surface of the micro-electrolysis reactor annular baffle is in the shape of an inverted frustum. The outer ring surface of the micro-electrolysis reactor annular baffle is connected to the inner wall of the micro-electrolysis cylinder body. The micro-electrolysis reactor conical baffle and the micro-electrolysis reactor annular baffle are both coaxial with the micro-electrolysis cylinder body; The height of the micro-electrolysis reactor annular baffle is lower than the height of the micro-electrolysis reactor air inlet branch pipe. The cone top of the micro-electrolysis reactor conical baffle is more than 20 cm higher than the micro-electrolysis reactor air inlet branch pipe.

[0019] The bottom surface of the Fenton reaction cylinder body is provided with a conical baffle of the Fenton reactor and an annular baffle of the Fenton reactor. The conical baffle of the Fenton reactor is located in the inner ring of the annular baffle of the Fenton reactor. The inner ring surface of the annular baffle of the Fenton reactor is in the shape of an inverted truncated cone. The outer ring surface of the annular baffle of the Fenton reactor is connected to the inner wall of the Fenton reaction cylinder body. Both the conical baffle of the Fenton reactor and the annular baffle of the Fenton reactor are coaxial with the Fenton reaction cylinder body. The height of the annular baffle of the Fenton reactor is lower than the height of the intake branch pipe of the Fenton reactor. The apex of the conical baffle of the Fenton reactor is more than 20 cm higher than the intake branch pipe of the Fenton reactor.

[0020] As described above, an exhaust pipe is provided at the top of the micro-electrolysis cylinder body, and a maintenance hole for the micro-electrolysis reactor is provided at the lower part of the side wall of the micro-electrolysis cylinder body; an overflow weir of the micro-electrolysis reactor is provided in the micro-electrolysis cylinder body above the water inlet of the circulation pump. The overflow weir of the micro-electrolysis reactor is connected to the water outlet of the micro-electrolysis reactor. A slant tube area of the micro-electrolysis reactor is provided in the micro-electrolysis cylinder body below the water inlet of the circulation pump. The slant tube area of the micro-electrolysis reactor includes multiple inclined pipes.

[0021] A chemical dosing port of the Fenton reactor is provided at the lower part of the side wall of the Fenton reaction cylinder body, and a maintenance hole for the Fenton reactor is also provided on the side wall of the Fenton reaction cylinder body; an overflow weir of the Fenton reactor is provided in the upper part of the Fenton reaction cylinder body. The overflow weir of the Fenton reactor is connected to the water outlet of the Fenton reactor.

[0022] As described above, the water outlet of the Fenton reactor is connected to the first inlet of the pipe mixer. The second inlet of the pipe mixer is connected to an external chemical dosing pipe. The outlet of the pipe mixer is connected to the top end of the central cylinder inlet pipe. The bottom end of the central cylinder inlet pipe extends to the bottom of the central cylinder. The top of the central cylinder is open and the bottom is closed. A stirrer is provided in the central cylinder. A water retaining cylinder that penetrates up and down is sleeved outside the central cylinder. A water passing gap is left between the inner walls of the central cylinder and the water retaining cylinder. The top of the side wall of the water retaining cylinder is connected to the top of the zinc-iron sedimentation tank. The top height of the central cylinder is lower than the top height of the water retaining cylinder; a conical baffle of the sedimentation tank is provided below the central cylinder, and the apex of the conical baffle of the sedimentation tank faces upward; a plurality of sedimentation tank sludge hoppers are provided at the bottom of the zinc-iron sedimentation tank; a sedimentation tank slant tube area is provided circumferentially between the inner wall of the zinc-iron sedimentation tank and the outer wall of the water retaining cylinder. An overflow weir of the sedimentation tank is provided in the zinc-iron sedimentation tank above the sedimentation tank slant tube area. The overflow weir of the sedimentation tank is connected to the water outlet of the sedimentation tank.

[0023] A method for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing skin pass mill, using the device for recycling zinc powder and iron powder in the wastewater of the hot-dip galvanizing skin pass mill as described above, the steps include:

[0024] Step S1: The pickling wastewater is first collected in a sump, and then the zinc powder and iron powder in the pickling wastewater are separated simultaneously by a solid-liquid separation device. The separated zinc powder and iron powder are collected in a storage tank, and the pickling wastewater after separating the zinc powder and iron powder is discharged into a sewage tank.

[0025] Step S2: The zinc powder and iron powder in the storage tank are first dehydrated by a first dehydration device. The wastewater after dehydration is discharged into the sewage tank described in Step S1, and the dehydrated zinc powder and iron powder enter a drying device for drying.

[0026] Step S3: Zinc powder, iron powder, clay, additives, and activated carbon are put into a first recovery device to make a ternary micro-electrolysis filler of iron-zinc-carbon.

[0027] Step S4: The ternary micro-electrolysis filler is put into a micro-electrolysis reactor, and at the same time, the wastewater to be treated is introduced into the micro-electrolysis reactor. Then the effluent of the micro-electrolysis reactor is transported to a Fenton reactor, and hydrogen peroxide is added to the Fenton reaction cylinder. The effluent of the Fenton reactor is mixed with an alkaline solution and then enters a zinc-iron sedimentation tank. Then a flocculant is added to the zinc-iron sedimentation tank. The obtained flocculent sludge containing zinc and iron enters a second dehydration device, and the effluent of the zinc-iron sedimentation tank is transported out to an external wastewater treatment device.

[0028] Step S5: The second dehydration device dehydrates the flocculent sludge. The obtained clear liquid is discharged into an external wastewater treatment device, and the flocculent sludge dehydrated by the second dehydration device enters a second recovery device.

[0029] Step S6: In the second recovery device, a binder and a pore-forming agent are first added to the flocculent sludge dehydrated by the second dehydration device, and then it is subjected to extrusion granulation and drying, and then high-temperature roasting. Finally, a desulfurizer product is obtained after cooling.

[0030] As described above, the solid-liquid separation device adopts a hydrocyclone or a sedimentation tank or a magnetic separation device, and the separation efficiency of zinc powder and iron powder is greater than 95%. The first dehydration device and the second dehydration device both adopt plate-and-frame filter presses, and the moisture content of the sludge after dehydration by the first dehydration device is lower than 75%, and the moisture content of the flocculent sludge after dehydration by the second dehydration device is lower than 70%.

[0031] As described above, in Step S3, the first recovery device mixes, granulates, dries, roasts, and cools zinc powder, iron powder, clay, additives, and activated carbon to obtain a ternary micro-electrolysis filler of iron-zinc-carbon, and the mass fractions of each raw material are as follows:

[0032]

[0033] The roasting temperature is 850 - 900 °C.

[0034] As described above, the particle size of the ternary micro-electrolysis filler is 10 - 20 mesh.

[0035] As described above, the hydraulic retention time of both the Fenton reactor and the micro-electrolysis reactor is 2 - 3 hours.

[0036] As described above, in step S6, the high-temperature calcination temperature is 350 - 550 °C, and the active components of the desulfurizer are iron oxide and zinc oxide.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0038] The present invention uses zinc powder and iron powder in the pickling wastewater of the skin pass mill to make a ternary micro-electrolysis filler, solves the pollution problem of zinc powder and iron powder, and at the same time obtains a highly efficient micro-electrolysis filler. When it is used in wastewater treatment, it has obvious environmental benefits. The iron sludge and zinc sludge generated after the use of the micro-electrolysis filler can be recycled to obtain desulfurizer products of iron oxide and zinc oxide, which are used in waste gas treatment, improving economic and environmental benefits, truly realizing the resource utilization of solid waste, saving resources and achieving low costs at the same time. Description of the Drawings

[0039] Figure 1 is the process flow diagram of the method for recycling zinc powder and iron powder in the pickling wastewater of the skin pass mill;

[0040] Figure 2 is the structural schematic diagram of the reaction tower and zinc-iron sedimentation tank for wastewater treatment;

[0041] Figure 3 is the bottom pipeline layout diagram of the micro-electrolysis reactor;

[0042] Figure 4 is the bottom pipeline layout diagram of the Fenton reactor;

[0043] Table 1 is the content table of zinc powder and iron powder in the pickling wastewater of the skin pass mill;

[0044] Table 2 is the comparison table of the treatment effects of phenolic wastewater before and after treatment;

[0045] Table 3 is the performance table of the desulfurizer;

[0046] In the figure: 1 - Inlet of the micro-electrolysis reactor; 2 - Exhaust pipe; 3 - Overflow weir of the micro-electrolysis reactor; 4 - Outlet of the micro-electrolysis reactor; 5 - Inlet of the circulation pump; 6 - Micro-electrolysis reactor; 7 - Inclined tube area of the micro-electrolysis reactor; 8 - Circulation pump; 9 - Main pipe of the circulation distribution pipe; 10 - Maintenance hole of the micro-electrolysis reactor; 11 - Branch pipe of the circulation distribution pipe; 12 - Main intake pipe of the micro-electrolysis reactor; 13 - Conical baffle of the micro-electrolysis reactor; 14 - Branch intake pipe of the micro-electrolysis reactor; 15 - Annular baffle of the micro-electrolysis reactor; 16 - Fenton reactor; 17 - Inlet of the Fenton reactor; 18 - Maintenance hole of the Fenton reactor; 19 - Overflow weir of the Fenton reactor; 20 - Outlet of the Fenton reactor; 21 - Main intake pipe of the Fenton reactor; 22 - Chemical dosing port of the Fenton reactor; 23 - Conical baffle of the Fenton reactor; 24 - Branch intake pipe of the Fenton reactor; 25 - Pipe mixer; 26 - Central cylinder; 27 - Outlet of the sedimentation tank; 28 - Inclined tube area of the sedimentation tank; 29 - Zinc-iron sedimentation tank; 30 - Hopper of the sedimentation tank; 31 - Mixer; 32 - Conical baffle of the sedimentation tank; 33 - Overflow weir of the sedimentation tank; 34 - Annular intake pipe; 35 - Intake ring; 36 - Annular baffle of the Fenton reactor. Specific implementation manner

[0047] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] Example 1

[0049] A device for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill. This device can use the iron-zinc-carbon ternary micro-electrolysis filler made from recycled zinc powder and iron powder for sewage treatment, and is suitable for purifying and treating wastewater containing refractory organic matter. It mainly removes pollutants such as COD, chromaticity and total phosphorus in the organic wastewater. The device includes a reaction tower and a zinc-iron sedimentation tank 29, wherein the reaction tower includes a micro-electrolysis reactor 6 and a Fenton reactor 16, and the micro-electrolysis reactor 6, the Fenton reactor 16 and the zinc-iron sedimentation tank 29 are connected in sequence.

[0050] The micro-electrolysis reactor 6 includes a micro-electrolysis cylinder body. An exhaust pipe 2 and a micro-electrolysis reactor water inlet 1 are arranged at the top of the micro-electrolysis cylinder body. The lower port of the micro-electrolysis reactor water inlet 1 extends downward to the lower part inside the micro-electrolysis cylinder body. An annular air inlet pipe 34 is arranged at the lower part inside the micro-electrolysis cylinder body. The annular air inlet pipe 34 is connected to a micro-electrolysis reactor air inlet main pipe 12 arranged on the micro-electrolysis cylinder body. A plurality of micro-electrolysis reactor air inlet branch pipes 14 are evenly distributed on the annular air inlet pipe 34. The air outlet direction of the micro-electrolysis reactor air inlet branch pipe 14 forms a set angle with the diameter direction of the annular air inlet pipe 34 where the micro-electrolysis reactor air inlet branch pipe 14 is located. A plurality of circulating water distribution pipe branch pipes 11 are circumferentially arranged at the lower part of the micro-electrolysis cylinder body. The water outlet of the circulating water distribution pipe branch pipe 11 extends into the micro-electrolysis cylinder body. The water outlet direction of the circulating water distribution pipe branch pipe 11 forms a set angle with the diameter direction of the micro-electrolysis cylinder body where the circulating water distribution pipe branch pipe 11 is located. A ring-shaped circulating water distribution pipe main pipe 9 is sleeved on the lower part of the micro-electrolysis cylinder body. Each circulating water distribution pipe branch pipe 11 is connected to the circulating water distribution pipe main pipe 9. The water inlet port of the circulating water distribution pipe main pipe 9 is connected to the water outlet of a circulating pump 8. The water inlet of the circulating pump 8 is connected to a circulating pump water inlet 5 on the upper part of the side wall of the micro-electrolysis cylinder body. The height of the circulating pump water inlet 5 is lower than the height of the micro-electrolysis reactor water outlet 4 arranged on the side wall of the micro-electrolysis cylinder body. The present invention uses a fluidized bed instead of a fixed bed, and makes the wastewater form a swirl inside the micro-electrolysis cylinder body through the circulating water distribution pipe branch pipes 11 and the micro-electrolysis reactor air inlet branch pipes 14 to ensure the efficient reaction between the wastewater and the ternary micro-electrolysis filler. A micro-electrolysis reactor conical baffle 13 and a micro-electrolysis reactor annular baffle 15 are arranged on the bottom surface of the micro-electrolysis cylinder body. The micro-electrolysis reactor conical baffle 13 is located inside the inner ring of the micro-electrolysis reactor annular baffle 15. The region surrounded by the inner ring surface of the micro-electrolysis reactor annular baffle 15 is in the shape of an inverted frustum. The outer ring surface of the micro-electrolysis reactor annular baffle 15 is connected to the inner wall of the micro-electrolysis cylinder body. The micro-electrolysis reactor conical baffle 13 and the micro-electrolysis reactor annular baffle 15 are both coaxial with the micro-electrolysis cylinder body. The height of the micro-electrolysis reactor annular baffle 15 is lower than the height of the micro-electrolysis reactor air inlet branch pipes 14. The apex of the micro-electrolysis reactor conical baffle 13 is more than 20 cm higher than the micro-electrolysis reactor air inlet branch pipes 14. The micro-electrolysis reactor conical baffle 13 is used to guide the water flow to form a swirl. The micro-electrolysis reactor annular baffle 15 is used to prevent dead angle sedimentation from occurring at the bottom periphery of the micro-electrolysis cylinder body and at the same time plays an auxiliary role in guiding the water flow. A micro-electrolysis reactor inspection hole 10 is arranged at the lower part of the side wall of the micro-electrolysis cylinder body. A micro-electrolysis reactor overflow weir 3 is arranged inside the micro-electrolysis cylinder body above the circulating pump water inlet 5. The micro-electrolysis reactor overflow weir 3 is connected to the micro-electrolysis reactor water outlet 4. A micro-electrolysis reactor inclined tube area 7 is arranged inside the micro-electrolysis cylinder body below the circulating pump water inlet 5. The micro-electrolysis reactor inclined tube area 7 includes a plurality of inclined pipes, so that suspended impurities and unreacted ternary micro-electrolysis filler particles in the wastewater are precipitated in the inclined tubes. The water flows upward along the inclined tubes, and the separated substances slide down along the inclined tubes to the bottom under the action of gravity to achieve the function of sedimentation separation.

[0051] The ternary micro-electrolysis filler is put into the micro-electrolysis reactor 6 from the overhaul hole 10 of the micro-electrolysis reactor. The wastewater to be treated flows into the micro-electrolysis cylinder body from the water inlet 1 of the micro-electrolysis reactor. Under the action of the intake branch pipe 14 of the micro-electrolysis reactor, a swirl is formed to improve the efficiency of the micro-electrolysis reaction. At the same time, the wastewater in the micro-electrolysis cylinder body flows upward from the bottom. The unreacted ternary micro-electrolysis filler and suspended impurities rising to the inclined pipe area 7 of the micro-electrolysis reactor are intercepted by the inclined pipes in the inclined pipe area 7 of the micro-electrolysis reactor in the solution below the inclined pipe area 7 of the micro-electrolysis reactor. When the liquid level height of the wastewater in the micro-electrolysis cylinder body reaches the water inlet 5 of the circulation pump, the wastewater is pumped by the circulation pump 8 and then flows back to the lower part of the micro-electrolysis cylinder body from the main circulation water distribution pipe 9 and the branch circulation water distribution pipe 11 in sequence, so that the reaction between the wastewater and the ternary micro-electrolysis filler is more sufficient. When the liquid level height reaches the height of the overflow weir 3 of the micro-electrolysis reactor, the wastewater treated by micro-electrolysis flows out through the overflow weir 3 of the micro-electrolysis reactor to the water outlet 4 of the micro-electrolysis reactor.

[0052] In this embodiment, as Figure 3 shown, the bottom of the micro-electrolysis reactor 6 adopts annular water distribution. The outlet direction of the branch circulation water distribution pipe 11 forms a 60° angle with the diameter direction of the micro-electrolysis cylinder body where the branch circulation water distribution pipe 11 is located. At the same time, the outlet direction of the branch circulation water distribution pipe 11 is inclined downward at an angle of 15° with the horizontal plane. The number of the branch circulation water distribution pipes 11 is 4 - 8. The outlet flow rate of the branch circulation water distribution pipe 11 is 1.7 - 2.0 m / s. The outlet flow rate of the circulation pump 8 is 50% - 100% of the flow rate of the water inlet 1 of the micro-electrolysis reactor. The outlet direction of the intake branch pipe 14 of the micro-electrolysis reactor forms a 45° angle with the diameter direction of the annular intake pipe 34 where the intake branch pipe 14 of the micro-electrolysis reactor is located. At the same time, the outlet direction of the intake branch pipe 14 of the micro-electrolysis reactor is inclined downward and forms an angle of 15° with the horizontal plane. The number of the intake branch pipes 14 of the micro-electrolysis reactor is 6 - 8. The outlet flow rate is greater than 2 m / s. The total intake air volume is designed according to the area of the liquid level in the reactor, and the design value is 5 - 7 m 3 / (m 2 ·h). The gas source adopts compressed air, and the intake air pressure is 0.4 - 0.7 Mpa. The above method is used to form gas-water swirl stirring in the micro-electrolysis reactor 6. The hydraulic retention time in the micro-electrolysis reactor 6 is 2 - 3 hours. Among them, the hydraulic retention time (HRT) = the effective volume (V) of the reaction device) / the influent flow rate (Q). Here, the reaction device is the micro-electrolysis reactor 6. According to the hydraulic retention time calculation formula, the hydraulic retention time is controlled by controlling the influent flow rate.

[0053] The Fenton reactor 16 includes a Fenton reaction cylinder body. At the top of the Fenton reaction cylinder body, there is a Fenton reactor water inlet 17. The outlet of the micro-electrolysis reactor 4 is connected to the upper port of the Fenton reactor water inlet 17. The lower port of the Fenton reactor water inlet 17 extends downward to the lower part inside the Fenton reaction cylinder body. At the bottom inside the Fenton reaction cylinder body, there is an air inlet ring 35. The air inlet ring 35 is connected to the Fenton reactor main air inlet pipe 21 arranged on the Fenton reaction cylinder body. A plurality of Fenton reactor air inlet branch pipes 24 are evenly arranged on the air inlet ring 35. The air outlet direction of the Fenton reactor air inlet branch pipe 24 forms a set angle with the diameter direction of the air inlet ring 35 where the Fenton reactor air inlet branch pipe 24 is located. The liquid inside the Fenton reaction cylinder body forms a swirling flow through the Fenton reactor air inlet branch pipe 24 to ensure the efficient reaction of the liquid inside the Fenton reaction cylinder body. At the bottom of the Fenton reaction cylinder body, there are a Fenton reactor conical baffle 23 and a Fenton reactor annular baffle 36. The Fenton reactor conical baffle 23 is located inside the inner ring of the Fenton reactor annular baffle 36. The inner ring surface of the Fenton reactor annular baffle 36 is in the shape of an inverted truncated cone. The outer ring surface of the Fenton reactor annular baffle 36 is connected to the inner wall of the Fenton reaction cylinder body. Both the Fenton reactor conical baffle 23 and the Fenton reactor annular baffle 36 are coaxial with the Fenton reaction cylinder body. The height of the Fenton reactor annular baffle 36 is lower than the height of the Fenton reactor air inlet branch pipe 24. The cone top of the Fenton reactor conical baffle 23 is more than 20 cm higher than the Fenton reactor air inlet branch pipe 24. At the lower part of the side wall of the Fenton reaction cylinder body, there is a Fenton reactor chemical dosing port 22 for adding hydrogen peroxide. On the side wall of the Fenton reaction cylinder body, there is also a Fenton reactor maintenance hole 18. At the upper part inside the Fenton reaction cylinder body, there is a Fenton reactor overflow weir 19. The Fenton reactor overflow weir 19 is connected to the Fenton reactor water outlet 20.

[0054] The effluent of the micro-electrolysis reactor 6 (i.e., the wastewater treated by micro-electrolysis) flows from the outlet 4 of the micro-electrolysis reactor to the inlet 17 of the Fenton reactor, and then enters the Fenton reactor 16. At the same time, hydrogen peroxide is added to the chemical dosing port 22 of the Fenton reactor to remove pollutants in the wastewater and convert divalent iron into trivalent iron. Similar to the micro-electrolysis reactor 6, the Fenton reactor 16 also uses air swirl stirring. Through the intake branch pipe 24 of the Fenton reactor, the wastewater treated by micro-electrolysis forms a swirl in the Fenton reaction cylinder to improve the reaction efficiency. After the preset hydraulic retention time of the Fenton reaction, the wastewater treated by the Fenton reaction passes through the overflow weir 19 of the Fenton reactor and the outlet 20 of the Fenton reactor in sequence and is discharged to the zinc-iron sedimentation tank 29.

[0055] In this embodiment, the intake main pipe 21 and the intake branch pipe 24 of the Fenton reactor are arranged at the bottom of the Fenton reactor 16. The outlet direction of the intake branch pipe 24 of the Fenton reactor forms a 60° angle with the diameter direction of the intake ring 35 where the intake branch pipe 24 of the Fenton reactor is located. At the same time, the outlet direction of the intake branch pipe 24 of the Fenton reactor is inclined downward at an angle of 15° with the horizontal plane. The number of the intake branch pipes 24 of the Fenton reactor is 6 to 8, the outlet gas velocity is greater than 2 m / s, and the total intake air volume is designed according to the area of the liquid level in the reactor, and the design value is 1 to 3 m 3 / (m 2 ·h). The gas source uses compressed air, the intake pressure is 0.4 to 0.7 Mpa, and the hydraulic retention time in the Fenton reactor 16 is also 2 to 3 hours.

[0056] Such as Figure 2As shown, the outlet 20 of the Fenton reactor is connected to the first inlet of the pipe mixer 25. The second inlet of the pipe mixer 25 is connected to an external chemical dosing pipe. The outlet of the pipe mixer 25 is connected to the top end of the central cylinder inlet pipe. The bottom end of the central cylinder inlet pipe extends to the bottom of the central cylinder 26. The top of the central cylinder 26 is open and the bottom is closed. A stirrer 31 is arranged inside the central cylinder 26. A water retaining cylinder that penetrates up and down is sleeved outside the central cylinder 26. There is a water passing gap between the inner walls of the central cylinder 26 and the water retaining cylinder. The top of the side wall of the water retaining cylinder is connected to the top of the zinc-iron sedimentation tank 29. The top height of the central cylinder 26 is lower than the top height of the water retaining cylinder. Thus, the water flow inside the central cylinder 26 can overflow from the top of the central cylinder 26 and flow into the water passing gap between the central cylinder 26 and the water retaining cylinder. A sedimentation tank conical baffle 32 is arranged below the central cylinder 26. The cone top of the sedimentation tank conical baffle 32 faces upward to rectify the flowing water from the water passing gap between the central cylinder 26 and the water retaining cylinder and guide the water flow to flow around. A plurality of sedimentation tank sludge hoppers 30 are arranged at the bottom of the zinc-iron sedimentation tank 29. A sedimentation tank inclined tube area 28 is arranged circumferentially between the inner wall of the zinc-iron sedimentation tank 29 and the outer wall of the water retaining cylinder. A sedimentation tank overflow weir 33 is arranged above the sedimentation tank inclined tube area 28 inside the zinc-iron sedimentation tank 29. The sedimentation tank overflow weir 33 is connected to the sedimentation tank outlet 27.

[0057] The effluent of the Fenton reactor 16 is first mixed with the alkali solution dosed in the chemical dosing pipe in the pipe mixer 25. The alkali solution is generally NaOH solution, or can also be mixed alkali (such as one or more of Na2CO3, NaOH, KOH), so that the pH of the solution is about 8.0, ensuring that the iron ions and zinc ions in the solution form precipitates. At the same time, a flocculant is dosed in the central cylinder 26 to make the precipitates of iron ions and zinc ions form flocculent sludge. In the present invention, the flocculant uses anionic polyacrylamide in polyacrylamide (PAM). After being stirred and mixed by the stirrer 31, the mixed liquid containing flocculent sludge first flows out from the upper part of the central cylinder 26 and then flows into the middle part of the zinc-iron sedimentation tank 29 through the water passing gap between the central cylinder 26 and the water retaining cylinder. At the same time, under the rectifying action of the sedimentation tank conical baffle 32, the liquid is dispersed around and then flows upward into the sedimentation tank inclined tube area 28. The flocculent sludge formed by iron ions and zinc ions sinks into the sedimentation tank sludge hopper 30 for temporary storage. The effluent of the zinc-iron sedimentation tank 29 is transported to a subsequent wastewater treatment device outside the present invention through the sedimentation tank outlet 27. The flocculent sludge in the sedimentation tank sludge hopper 30 enters other recycling equipment. In the present invention, the flocculent sludge in the sedimentation tank sludge hopper 30 is transported to the second dehydration device.

[0058] Example 2

[0059] In specific implementation, the process flow of a method for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing skin pass mill of the present invention is as Figure 1 shown.

[0060] A method for recycling zinc powder and iron powder from the wastewater of a hot-dip galvanizing skin pass mill, using the device for recycling zinc powder and iron powder from the wastewater of a hot-dip galvanizing skin pass mill described in Example 1, includes the following steps:

[0061] Step S1: First, collect the wastewater of the skin pass mill in a collecting pool located below the skin pass mill. Then, simultaneously separate the zinc powder and iron powder in the wastewater of the skin pass mill through a solid-liquid separation device, ensuring that the separation efficiency of the zinc powder and iron powder is greater than 95%. Collect the separated zinc powder and iron powder in a storage tank. At the same time, the wastewater of the skin pass mill after separating the zinc powder and iron powder is discharged into a sewage pool and then enters the sewage treatment system of a large cold rolling mill outside the present invention for subsequent treatment. The solid-liquid separation device used in this embodiment is a hydrocyclone or a sedimentation tank or a magnetic separation device;

[0062] Step S2: The zinc powder and iron powder in the storage tank are first dehydrated by a first dehydration device. The wastewater after dehydration is discharged into the sewage pool described in Step S1. The dehydrated zinc powder and iron powder enter a drying device for drying, and then the dried zinc powder and iron powder are stored and transported outside to a first recovery device. The first dehydration device uses a plate and frame filter press; the drying device uses a fluidized bed dryer, which mainly includes a filter, a fluidized bed, a fluidized bed blower, and a cyclone separator; the dehydrated zinc powder and iron powder are added into the fluidized bed of the fluidized bed dryer by a feeder. The air filtered by the filter is heated and then sent into the bottom of the fluidized bed by the fluidized bed blower and contacts the dehydrated zinc powder and iron powder through a distribution plate to form a fluidized state to achieve heat and mass transfer between gas and solid. The zinc powder and iron powder are discharged from the discharge port of the fluidized bed dryer after drying, and the waste gas is discharged after the solid powder is recovered by the cyclone separator at the top of the fluidized bed dryer. After dehydration by the first dehydration device, the moisture content of the sludge is lower than 75%.

[0063] Step S3: The dried zinc powder and iron powder, as well as additional clay, additives, and activated carbon, are made into a ternary micro-electrolysis filler of iron-zinc-carbon (i.e., the first product of the present invention) in a first recovery device. The equipment used in the first recovery device mainly includes a mixer, a granulator, a dryer (such as a horizontal multi-chamber fluidized bed dryer, a belt dryer, a box dryer, a rotary dryer, etc.), a sintering furnace, and a cooler. In this process, the dried zinc powder and iron powder do not need to be screened. The process of preparing the ternary micro-electrolysis filler includes processes such as mixing, granulating, drying, roasting, and cooling. In the mixing process, the clay, additives, zinc powder, iron powder, and activated carbon are mixed, and the additive is sodium carboxymethyl cellulose, which not only plays a binding role but also a pore-forming role. The mass fractions of each raw material are as follows:

[0064]

[0065] According to the ratio of zinc and iron in the zinc powder and iron powder mixture after drying in step S2, iron powder is added to the zinc powder and iron powder mixture to control the mass mixing ratio of iron powder and zinc powder. The zinc powder, iron powder, clay, additive, and activated carbon are mixed and granulated using a granulator in the first recovery device. After granulation, it is first dried and then calcined at a high temperature. The calcination temperature is controlled at 850 - 900 °C, and finally a ternary micro-electrolysis filler product of iron-zinc-carbon with relatively high strength is obtained.

[0066] Step S4: The ternary micro-electrolysis filler obtained in step S3 is put into the micro-electrolysis reactor 6. At the same time, the wastewater to be treated is introduced into the micro-electrolysis reactor 6. The dosage of the added ternary micro-electrolysis filler is 0.05 - 0.2 kg / L. The ternary micro-electrolysis filler is initially put into the micro-electrolysis reactor 6 from the maintenance hole 10 of the micro-electrolysis reactor, and subsequently, granulated ternary micro-electrolysis filler can be supplemented and added from the water inlet 1 of the micro-electrolysis reactor. After that, the effluent of the micro-electrolysis reactor 6 is transported to the Fenton reactor 16, and hydrogen peroxide is added to the Fenton reaction cylinder at the same time. The effluent of the Fenton reactor 16 is mixed with the alkali solution and then enters the zinc-iron sedimentation tank 29. Then, a flocculant is added to the zinc-iron sedimentation tank 29. The flocculent sludge containing zinc and iron enters the second dehydration device, and the effluent of the zinc-iron sedimentation tank 29 is transported out to a wastewater treatment device outside the present invention. The micro-electrolysis reactor 6 and the Fenton reactor 16 together form a reaction tower. As Figure 2 shown, the reaction tower adopts a micro-electrolysis - Fenton coupling process, where the micro-electrolysis reaction device is the micro-electrolysis reactor 6, and the device for the Fenton coupling process is the Fenton reactor 16. The micro-electrolysis reaction device, the micro-electrolysis reactor 6, uses a fluidized bed instead of a conventional fixed bed to ensure efficient reaction. The reaction tower is suitable for purifying and treating wastewater containing refractory organic matter. The iron-zinc-carbon ternary micro-electrolysis filler is continuously consumed in the reaction tower. Through chemical reactions, pollutants such as COD, chromaticity, and total phosphorus in the organic wastewater are removed. At the same time, the iron-zinc-carbon ternary micro-electrolysis filler is converted into zinc ions and iron ions, and then the zinc ions and iron ions are precipitated by adding an alkali solution, so as to facilitate separation from the solution. The liquid discharged from the reaction tower enters the zinc-iron sedimentation tank 29. A flocculant is added to the zinc-iron sedimentation tank 29 to form flocculent sludge from the precipitation of iron ions and zinc ions, and then the flocculent sludge is transported to the second dehydration device; the effluent of the zinc-iron sedimentation tank 29 is transported out to a wastewater treatment device outside the present invention.

[0067] The ternary micro-electrolysis filler product prepared in step S3 is used in the wastewater pretreatment process of this step. To improve the reaction efficiency, the ternary micro-electrolysis filler particles are selected with a particle size of 10 - 20 mesh, and the micro-electrolysis reactor 6 uses a gas-water swirl mixing method to ensure efficient mass transfer efficiency.

[0068] The present invention adopts a ternary micro-electrolysis reaction system. Since a metal is added to the binary micro-electrolysis system, the number of primary batteries in the system increases, the electron transfer rate in the system speeds up, the number of receptors increases, and the mass transfer rate of pollutants to the electrode surface also significantly accelerates, thereby greatly improving the treatment efficiency. Further, the carbon element source used in the raw materials of the ternary micro-electrolysis technology in the present invention can be used waste powdered activated carbon, and the metal materials are recycled zinc powder and iron powder. The raw materials are simple and the cost is low. Starting from "treating waste with waste", compared with the existing zinc powder and iron powder recycling technologies, the present invention does not require the purification of zinc powder and iron powder, nor does it require the purity of zinc and iron in the product. Therefore, the production cost of the ternary micro-electrolysis filler product in the present invention is relatively low.

[0069] Step S5: The second dehydration device dehydrates the flocculent sludge. The second dehydration device uses a plate and frame filter press. After the flocculent sludge in the sedimentation tank hopper 30 is transported to the plate and frame filter press for dehydration treatment, the obtained clear liquid is discharged into the wastewater treatment device outside the present invention described in step S4, and the flocculent sludge dehydrated by the second dehydration device enters the second recovery device; the water content of the flocculent sludge dehydrated by the second dehydration device is lower than 70%.

[0070] Step S6: Manufacture a desulfurizer in the second recovery device. The equipment used in the second recovery device mainly includes a mixer, a granulator, a dryer, a sintering furnace, and a cooler. First, a binder and a pore-forming agent are added to the flocculent sludge dehydrated by the second dehydration device. The binder is selected from bentonite, diatomite, kaolin, refractory clay, etc., and the pore-forming agent is selected from starch, methyl cellulose, chemical paste, etc. Then, it is extruded into granules and dried, and finally subjected to high-temperature roasting. After cooling, the second product of the present invention, namely the desulfurizer product, is obtained. The pore-forming agent can decompose at high temperature to form a large number of voids inside the particles, increasing the specific surface area of the desulfurizer. The high-temperature roasting temperature is 350-550°C. The effective components of the desulfurizer are iron oxide and zinc oxide, which are used to remove H2S and some simple organic sulfides.

[0071] The removal of gas H2S generally can be divided into two categories: dry method and wet method. The wet method includes absorption method and wet oxidation method. Its desulfurization load is high, but it generally has disadvantages such as large power consumption, large equipment volume, high operation cost, and harsh control conditions. The dry method includes iron oxide method, zinc oxide method, activated carbon method, molecular sieve method, ion exchange method, membrane separation method, etc. The dry method is suitable for the treatment of low-sulfur-containing gases and is widely used because of its simple process, convenient operation, high desulfurization accuracy, and low energy consumption. The desulfurizer manufactured by the present invention can be used in the dry method for the removal of gas H2S. In addition, the desulfurizer product obtained by the present invention can be regenerated and reused multiple times, and another part of the desulfurizer that cannot be regenerated can also be used as zinc oxide waste as a raw material for producing zinc powder, realizing the recycling and regeneration of resources.

[0072] Taking the wastewater from the hot-dip galvanizing temper mill in a steel enterprise as the research object, the contents of zinc powder and iron powder in the wastewater are shown in Table 1. Among them, SS represents suspended solids.

[0073] Table 1 Contents of zinc powder and iron powder in the temper mill wastewater

[0074]

[0075] It can be seen from Table 1 that the contents of zinc powder and iron powder in the suspended solids of the temper mill wastewater are relatively high, and it has good recovery value.

[0076] Example 3

[0077] In this example, the raw materials and fractions in step S3 are selected as follows:

[0078]

[0079] The roasting temperature is controlled at 900 °C,

[0080] The high-temperature roasting temperature in step S6 is 450 °C,

[0081] Other steps and parameters are the same as those in Example 2.

[0082] In this example, 15-mesh ternary micro-electrolysis packing is obtained. A certain phenol-containing wastewater is selected as the treatment object of the present invention, and the water quality before and after treatment is monitored and analyzed. The specific results are shown in Table 2. Among them, COD represents chemical oxygen demand.

[0083] Table 2 Comparison of treatment effects of phenol-containing wastewater before and after treatment

[0084] Item COD (mg / L) Chromaticity (dilution multiple) Total phosphorus (mg / L) Before treatment 2350 30 1.5 After treatment 180 1 0.2

[0085] It can be seen from Table 2 that the ternary micro-electrolysis packing prepared by the present invention and its treatment process can effectively remove COD, chromaticity and total phosphorus. The removal rate of COD reaches more than 92%, and the treatment effect is good, with good environmental benefits.

[0086] The desulfurizer prepared in this example takes H2S as the treatment object, and the specific results are shown in Table 2.

[0087] Table 3 Performance of the desulfurizer

[0088] Item Working sulfur capacity (%) Pore volume (ml / g) Desulfurizer 30 0.3

[0089] It can be seen from Table 2 that the performance of the desulfurizer prepared by the present invention is good, meeting the usage requirements, and having good economic benefits.

[0090] The method of the present invention can recover zinc powder and iron powder simultaneously and has a higher recovery efficiency compared with the prior art, which is mainly reflected in: in step S1, zinc powder, iron powder and other impurities are separated from the wastewater together, without the need for other separation measures, and there will be no loss of materials. Almost all zinc powder and iron powder can be separated in the separation of the first step; in steps S2 and S3, the zinc powder and iron powder do not need to be screened and can be directly added with iron powder, activated carbon, additives, clay, etc. to be sintered into a ternary micro-electrolysis material. The materials do not need to be purified and there is almost no loss; in steps S4, S5 and S6, the zinc element and iron element in the ternary micro-electrolysis filler are first converted into ions and then become flocculent sludge through the chemical precipitation method. The loss of zinc ions and iron ions is very small. Finally, the flocculent sludge containing zinc and iron is used to make a desulfurizer. In the whole process, the loss of zinc element and iron element is small. Zinc and iron are recycled twice, and the finally used desulfurizer can still be used as the raw material of zinc and iron for further recycling.

[0091] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. Method for recycling zinc powder and iron powder in wastewater from hot-dip galvanizing temper mill, characterized in that the steps Including: Step S1: The pickling wastewater is first collected in a sump, and then the zinc powder and iron powder in the pickling wastewater are simultaneously separated by a solid-liquid separation device. The separated zinc powder and iron powder are collected in a storage tank, and the pickling wastewater after separating the zinc powder and iron powder is discharged into a sewage tank; Step S2: The zinc powder and iron powder in the storage tank are first dehydrated by a first dehydration device. The wastewater after dehydration is discharged into the sewage tank described in Step S1, and the zinc powder and iron powder after dehydration enter a drying device for drying; Step S3: Zinc powder, iron powder, clay, additives, and activated carbon are put into a first recovery device to make a ternary micro-electrolysis filler of iron-zinc-carbon; Step S4: The ternary micro-electrolysis filler is put into a micro-electrolysis reactor (6), and at the same time, the wastewater to be treated is introduced into the micro-electrolysis reactor (6); then the effluent of the micro-electrolysis reactor (6) is transported to a Fenton reactor (16), and hydrogen peroxide is added to the Fenton reaction cylinder; the effluent of the Fenton reactor (16) is mixed with an alkali solution and then enters a zinc-iron sedimentation tank (29), and then a flocculant is added to the zinc-iron sedimentation tank (29). The flocculent sludge containing zinc and iron enters a second dehydration device, and the effluent of the zinc-iron sedimentation tank (29) is transported out to an external wastewater treatment device; Step S5: The second dehydration device dehydrates the flocculent sludge. The obtained clear liquid is discharged into an external wastewater treatment device, and the flocculent sludge dehydrated by the second dehydration device enters a second recovery device; Step S6: In the second recovery device, a binder and a pore-forming agent are first added to the flocculent sludge dehydrated by the second dehydration device, then extrusion granulation and drying are carried out, and then high-temperature roasting is carried out. Finally, a desulfurizer product is obtained after cooling; 2. The method for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill according to claim 1, characterized in that, The solid-liquid separation device adopts a hydrocyclone or a sedimentation tank or a magnetic separation device. The separation efficiency of zinc powder and iron powder is greater than 95%. Both the first dehydration device and the second dehydration device adopt plate-and-frame filter presses. After dehydration by the first dehydration device, the moisture content of the sludge is lower than 75%. After dehydration by the second dehydration device, the moisture content of the flocculent sludge is lower than 70%.

3. The method for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill according to claim 1, characterized in that In Step S3, the first recovery device mixes, granulates, dries, roasts, and cools zinc powder, iron powder, clay, additives, and activated carbon to obtain a ternary micro-electrolysis filler, and the mass fractions of the respective raw materials are as follows: The roasting temperature is 850-900 °C.

4. The method for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill according to claim 1, characterized in that, The particle size of the ternary micro-electrolysis filler is 10-20 mesh.

5. The method for recycling zinc powder and iron powder from the wastewater of a hot-dip galvanizing temper mill according to claim 1, characterized in that, The hydraulic retention time of both the Fenton reactor (16) and the micro-electrolysis reactor (6) is 2-3 hours.

6. The method for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing skin pass mill according to claim 1, characterized in that, In Step S6, the high-temperature roasting temperature is 350-550 °C, and the effective components of the desulfurizer are iron oxide and zinc oxide.

7. Device for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing skin pass mill, for implementing the method for recycling zinc powder and iron powder in the wastewater of the hot-dip galvanizing skin pass mill according to claim 1, comprising a micro-electrolysis reactor (6), characterized in that, It also includes a Fenton reactor (16) and a zinc-iron sedimentation tank (29). A micro-electrolysis reactor water inlet (1) is provided at the top of the micro-electrolysis cylinder of the micro-electrolysis reactor (6). The lower port of the micro-electrolysis reactor water inlet (1) extends downward to the lower part inside the micro-electrolysis cylinder. An annular air inlet pipe (34) is provided in the lower part inside the micro-electrolysis cylinder. The annular air inlet pipe (34) is connected to a micro-electrolysis reactor air inlet main pipe (12) provided on the micro-electrolysis cylinder. A plurality of micro-electrolysis reactor air inlet branch pipes (14) are evenly distributed on the annular air inlet pipe (34). The outlet direction of the micro-electrolysis reactor air inlet branch pipe (14) forms a set angle with the diameter direction of the annular air inlet pipe (34) where the micro-electrolysis reactor air inlet branch pipe (14) is located. A plurality of circulating water distribution pipe branch pipes (11) are circumferentially provided at the lower part of the micro-electrolysis cylinder. The water outlet of the circulating water distribution pipe branch pipe (11) extends into the micro-electrolysis cylinder. The water outlet direction of the circulating water distribution pipe branch pipe (11) forms a set angle with the diameter direction of the micro-electrolysis cylinder where the circulating water distribution pipe branch pipe (11) is located. A circular circulating water distribution pipe main pipe (9) is sleeved at the lower part of the micro-electrolysis cylinder. Each circulating water distribution pipe branch pipe (11) is connected to the circulating water distribution pipe main pipe (9). The water inlet port of the circulating water distribution pipe main pipe (9) is connected to the water outlet of a circulating pump (8). The water inlet of the circulating pump (8) is connected to a circulating pump water inlet (5) at the upper part of the side wall of the micro-electrolysis cylinder. The height of the circulating pump water inlet (5) is lower than the height of the micro-electrolysis reactor water outlet (4) provided on the side wall of the micro-electrolysis cylinder. A Fenton reactor water inlet (17) is provided at the top of the Fenton reaction cylinder of the Fenton reactor (16). The micro-electrolysis reactor water outlet (4) is connected to the upper port of the Fenton reactor water inlet (17). The lower port of the Fenton reactor water inlet (17) extends downward to the lower part inside the Fenton reaction cylinder. An air inlet ring (35) is provided at the bottom inside the Fenton reaction cylinder. The air inlet ring (35) is connected to a Fenton reactor air inlet main pipe (21) provided on the Fenton reaction cylinder. A plurality of Fenton reactor air inlet branch pipes (24) are evenly provided on the air inlet ring (35). The outlet direction of the Fenton reactor air inlet branch pipe (24) forms a set angle with the diameter direction of the air inlet ring (35) where the Fenton reactor air inlet branch pipe (24) is located. Ternary micro-electrolysis fillers are put into the micro-electrolysis reactor (6).

8. The device for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill according to claim 7, characterized in that, The bottom surface of the micro-electrolysis cylinder body is provided with a conical baffle (13) of the micro-electrolysis reactor and an annular baffle (15) of the micro-electrolysis reactor. The conical baffle (13) of the micro-electrolysis reactor is located in the inner ring of the annular baffle (15) of the micro-electrolysis reactor. The area surrounded by the inner ring surface of the annular baffle (15) of the micro-electrolysis reactor is in the shape of an inverted frustum. The outer ring surface of the annular baffle (15) of the micro-electrolysis reactor is connected to the inner wall of the micro-electrolysis cylinder body. Both the conical baffle (13) of the micro-electrolysis reactor and the annular baffle (15) of the micro-electrolysis reactor are coaxial with the micro-electrolysis cylinder body. The height of the annular baffle (15) of the micro-electrolysis reactor is lower than the height of the air inlet branch pipe (14) of the micro-electrolysis reactor. The apex of the conical baffle (13) of the micro-electrolysis reactor is more than 20 cm higher than the air inlet branch pipe (14) of the micro-electrolysis reactor. The bottom surface of the Fenton reaction cylinder body is provided with a conical baffle (23) of the Fenton reactor and an annular baffle (36) of the Fenton reactor. The conical baffle (23) of the Fenton reactor is located in the inner ring of the annular baffle (36) of the Fenton reactor. The inner ring surface of the annular baffle (36) of the Fenton reactor is in the shape of an inverted frustum. The outer ring surface of the annular baffle (36) of the Fenton reactor is connected to the inner wall of the Fenton reaction cylinder body. Both the conical baffle (23) of the Fenton reactor and the annular baffle (36) of the Fenton reactor are coaxial with the Fenton reaction cylinder body. The height of the annular baffle (36) of the Fenton reactor is lower than the height of the air inlet branch pipe (24) of the Fenton reactor. The apex of the conical baffle (23) of the Fenton reactor is more than 20 cm higher than the air inlet branch pipe (24) of the Fenton reactor.

9. The device for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill according to claim 8, characterized in that, The top of the micro-electrolysis cylinder body is provided with an exhaust pipe (2). A maintenance hole (10) of the micro-electrolysis reactor is provided at the lower part of the side wall of the micro-electrolysis cylinder body. Above the water inlet of the circulation pump (5) in the micro-electrolysis cylinder body, an overflow weir (3) of the micro-electrolysis reactor is provided. The overflow weir (3) of the micro-electrolysis reactor is connected to the water outlet (4) of the micro-electrolysis reactor. Below the water inlet of the circulation pump (5) in the micro-electrolysis cylinder body, an inclined pipe area (7) of the micro-electrolysis reactor is provided. The inclined pipe area (7) of the micro-electrolysis reactor includes a plurality of inclined pipes. A chemical dosing port (22) of the Fenton reactor is provided at the lower part of the side wall of the Fenton reaction cylinder body. A maintenance hole (18) of the Fenton reactor is also provided on the side wall of the Fenton reaction cylinder body. An overflow weir (19) of the Fenton reactor is provided in the upper part of the Fenton reaction cylinder body. The overflow weir (19) of the Fenton reactor is connected to the water outlet (20) of the Fenton reactor.

10. The device for recycling zinc powder and iron powder in the wastewater of a hot-dip galvanizing temper mill according to claim 9, characterized in that, The outlet (20) of the Fenton reactor is connected to the first inlet of the pipe mixer (25). The second inlet of the pipe mixer (25) is connected to an external chemical dosing pipe. The outlet of the pipe mixer (25) is connected to the top end of the central cylinder inlet pipe. The bottom end of the central cylinder inlet pipe extends to the bottom of the central cylinder (26). The top of the central cylinder (26) is open and the bottom is closed. A stirrer (31) is arranged inside the central cylinder (26). A water retaining cylinder that penetrates up and down is sleeved outside the central cylinder (26). A water passing gap is left between the inner wall of the central cylinder (26) and the water retaining cylinder. The top of the side wall of the water retaining cylinder is connected to the top of the zinc-iron sedimentation tank (29). The top height of the central cylinder (26) is lower than the top height of the water retaining cylinder. A sedimentation tank conical baffle (32) is arranged below the central cylinder (26), and the cone top of the sedimentation tank conical baffle (32) faces upward. A plurality of sedimentation tank sludge hoppers (30) are arranged at the bottom of the zinc-iron sedimentation tank (29). A sedimentation tank inclined tube area (28) is arranged circumferentially between the inner wall of the zinc-iron sedimentation tank (29) and the outer wall of the water retaining cylinder. A sedimentation tank overflow weir (33) is arranged in the zinc-iron sedimentation tank (29) above the sedimentation tank inclined tube area (28). The sedimentation tank overflow weir (33) is connected to the sedimentation tank outlet (27).

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