System and method for comprehensively treating zinc dross

Abstract

The present invention discloses a system and method for comprehensively treating zinc dross. Among them, the system for comprehensively treating zinc dross includes: a screening device, a ball mill, a powder-ash separation unit, a pickling device, a first solid-liquid separation device, and an evaporation and crystallization device. Using this system to comprehensively treat zinc dross enables thorough separation of each material component in the zinc dross, significantly improving the zinc recovery rate (the zinc recovery rate is as high as over 99%), and the process flow is simple, the operation is convenient, the energy consumption is low, and it is environmentally friendly; in addition, the impurity element chlorine in the zinc dross is well discharged, avoiding adverse effects on the hydrometallurgical zinc system, and the zinc chloride obtained by comprehensive treatment can also be sold as a product, having good economic benefits and environmental emission reduction benefits.

Description

Technical Field

[0001] The present invention belongs to the field of metallurgy, and particularly relates to a system and method for comprehensively treating zinc dross. Background Art

[0002] In the smelting process of zinc hydrometallurgy, due to the high temperature, the surface zinc liquid is easily oxidized by air, and a layer of zinc oxide dross is formed on the surface of the zinc melting pool. The dross generation rate is 3% - 5%. During the zinc smelting process, in order not to affect production, it is necessary to regularly remove part of the dross to maintain a certain thickness of the dross layer. Before dross removal, usually solid ammonium chloride needs to be sprinkled and fully stirred to react with zinc oxide to form zinc chloride. Because the melting point of zinc chloride (about 283°C) is lower than that of zinc (419.5°C), this reaction destroys the zinc oxide film in the dross, so that the zinc liquid wrapped in the dross layer flows out, reducing the zinc content in the dross and increasing the direct recovery rate of zinc. Therefore, zinc dross is a mixture of zinc oxide, zinc chloride, and metallic zinc, containing more than 80% zinc, and has high recycling value. Because the zinc dross contains part of zinc chloride, the chlorine content in the dross is 3% - 5%. When comprehensively recovering zinc, the impurity chlorine must be removed to reduce the impact on the zinc hydrometallurgy system.

[0003] The patent application with the application number 20111037769.6 discloses a method for extracting metallic zinc powder with different uses from zinc dross. The main process is that the dross is repeatedly ground by a ball mill and then screened to separate zinc powder and zinc ash with different particle sizes. This process has three deficiencies: first, massive zinc is not easily ground fine, the grinding efficiency is low, and repeated grinding increases energy consumption; second, the complete separation of zinc powder and zinc ash is not achieved, and the purity of zinc powder is low; third, the separation of zinc oxide and zinc chloride is not achieved, the zinc ash contains chlorine, and when it is returned to the fluidized bed furnace for batching, the flue gas contains high chlorine, which corrodes equipment and is not friendly to the environment.

[0004] Therefore, the existing methods for treating zinc dross need to be improved. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems in the related technologies to some extent. For this reason, an object of the present invention is to provide a system and method for comprehensively treating zinc dross. Using this system to separate the various material components in zinc dross, it has good separation effect, significantly improves the recovery rate of zinc, is easy to operate, environmentally friendly, and the impurity chlorine element is well removed, realizing resource utilization.

[0006] In the first aspect of the present invention, the present invention provides a system for comprehensively treating zinc dross. According to an embodiment of the present invention, the system for comprehensively treating zinc dross includes:

[0007] A screening device, the screening device having a zinc dross inlet, a massive zinc outlet, and an undersize outlet;

[0008] A ball mill, the ball mill having an undersize inlet, a zinc particle outlet, and a zinc powder ash outlet, the undersize inlet being connected to the undersize outlet;

[0009] A powder ash separation unit, the powder ash separation unit having a zinc powder ash inlet, a zinc powder outlet, and a zinc ash outlet, the zinc powder ash inlet being connected to the zinc powder ash outlet;

[0010] A pickling device, the pickling device having a zinc ash inlet, a hydrochloric acid pickling solution inlet, and a pickled solution outlet, the zinc ash inlet being connected to the zinc ash outlet;

[0011] A first solid-liquid separation device, the first solid-liquid separation device having a pickled solution inlet, a pickling filtrate outlet, and a pickling residue outlet, the pickled solution inlet being connected to the pickled solution outlet;

[0012] An evaporation crystallization device, the evaporation crystallization device having a pickling filtrate inlet, an evaporation water outlet, and a zinc chloride crystal outlet, the pickling filtrate inlet being connected to the pickling filtrate outlet.

[0013] A system for comprehensively treating zinc dross according to an embodiment of the present invention, by supplying the zinc dross to a screening device for preliminary screening to separate out massive zinc and undersize material containing zinc particles and zinc ash powder, so that the massive zinc can be first separated from the zinc dross. The undersize material containing zinc particles and zinc ash powder is supplied to a ball mill for ball milling under a negative pressure environment to separate out zinc particles and zinc powder ash, so that the zinc particles can be continuously separated from the zinc dross. Then the zinc powder ash is supplied to a powder ash separation unit to separate out zinc powder and zinc ash, and the zinc ash is supplied to a pickling device to contact with a hydrochloric acid pickling solution for pickling. The obtained pickled solution is supplied to a first solid-liquid separation device for first solid-liquid separation to obtain a pickling filtrate and a pickling residue. Finally, the pickling filtrate is supplied to an evaporation crystallization device for treatment to obtain evaporation water and zinc chloride crystals. Using this system to comprehensively treat zinc dross makes the separation of each material component in the zinc dross complete, significantly improves the zinc recovery rate (the zinc recovery rate is as high as over 99%), and has a simple process flow, easy operation, low energy consumption, and environmental friendliness. In addition, the impurity element chlorine in the zinc dross is well removed, avoiding adverse effects on the hydrometallurgical zinc system. The zinc chloride obtained by evaporation crystallization of the pickling filtrate can also be sold as a product, having good economic benefits and environmental emission reduction benefits.

[0014] In addition, the system for comprehensively treating zinc dross according to the above embodiment of the present invention may further have the following additional technical features:

[0015] In some embodiments of the present invention, the zinc powder and ash separation unit includes a cyclone dust collector and a bag filter connected in sequence. Thus, after the zinc powder ash discharged from the ball mill is supplied to the zinc powder and ash separation unit, under the action of the cyclone dust collector, the zinc powder is collected in the cyclone dust collector, and the relatively light zinc ash finally enters the bag filter, thereby realizing the separation of zinc powder and zinc ash.

[0016] In some embodiments of the present invention, the above system further includes: a forming device having a bulk zinc inlet, a zinc particle inlet, and a pellet outlet, wherein the bulk zinc inlet is connected to the bulk zinc outlet, and the zinc particle inlet is connected to the zinc particle outlet. Thus, the bulk zinc and zinc particles can be pelletized and formed respectively and then returned to the zinc melting furnace, thereby improving the zinc recovery rate.

[0017] In some embodiments of the present invention, the above system further includes: a water washing device having a pickling filter residue inlet, a water washing liquid inlet, and a post-water washing liquid outlet, wherein the pickling filter residue inlet is connected to the pickling filter residue outlet; a second solid-liquid separation device having a post-water washing liquid inlet, a water washing filtrate outlet, and a water washing filter residue outlet, wherein the post-water washing liquid inlet is connected to the post-water washing liquid outlet, and the water washing filtrate outlet is connected to the hydrochloric acid washing liquid inlet. Thus, by washing the pickling filter residue, the obtained water washing filter residue is supplied as a zinc-containing raw material to the zinc leaching process of the hydrometallurgical system, thereby improving the zinc recovery rate, and performing a second solid-liquid separation on the post-water washing liquid and returning the obtained water washing filtrate to the pickling process, thereby saving the production cost.

[0018] In the second aspect of the present invention, the present invention provides a method for comprehensively treating zinc dross using the above system. According to the embodiments of the present invention, the method includes:

[0019] (1) Supplying the zinc dross to a screening device for screening treatment to separate bulk zinc and undersize materials containing zinc particles and zinc powder ash;

[0020] (2) Under a negative pressure environment, supplying the undersize materials containing zinc particles and zinc powder ash to a ball mill for ball milling to separate zinc particles and zinc powder ash;

[0021] (3) Supplying the zinc powder ash to the zinc powder and ash separation unit to obtain separated zinc powder and zinc ash;

[0022] (4) Supplying the zinc ash to a pickling device to contact with hydrochloric acid washing liquid to obtain post-pickling liquid;

[0023] (5) Supplying the post-pickling liquid to a first solid-liquid separation device for treatment to obtain pickling filtrate and pickling filter residue;

[0024] (6) Feed the pickling filtrate into an evaporation crystallization device for treatment to obtain evaporated water and zinc chloride crystals.

[0025] According to the method for comprehensively treating zinc dross using the above system according to an embodiment of the present invention, by feeding the zinc dross into a screening device for preliminary screening, massive zinc and undersize materials containing zinc particles and zinc ash powder are separated. Thus, the massive zinc can be separated from the zinc dross first. The undersize materials containing zinc particles and zinc ash powder are fed into a ball mill under a negative pressure environment for ball milling to separate zinc particles and zinc powder ash, so that the zinc particles can be continuously separated from the zinc dross. Then, the zinc powder ash is fed into a powder ash separation unit to separate zinc powder and zinc ash, and the zinc ash is fed into a pickling device to contact with hydrochloric acid pickling liquor for pickling. The pickled solution obtained is fed into a first solid-liquid separation device for first solid-liquid separation to obtain a pickling filtrate and pickling filter residue. Finally, the pickling filtrate is fed into an evaporation crystallization device for treatment to obtain evaporated water and zinc chloride crystals. Using this method to comprehensively treat zinc dross makes the separation of each material component in the zinc dross thorough, significantly improves the zinc recovery rate (the zinc recovery rate is as high as over 99%), and the process flow is simple, the operation is convenient, the energy consumption is low, and it is environmentally friendly. In addition, the impurity element chlorine in the zinc dross is well removed, avoiding adverse effects on the hydrometallurgical zinc system. The zinc chloride obtained by evaporation crystallization of the pickling filtrate can also be sold as a product, having good economic benefits and environmental emission reduction benefits.

[0026] In addition, the method for comprehensively treating zinc dross using the above system according to the above embodiment of the present invention may also have the following additional technical features:

[0027] In some embodiments of the present invention, in step (4), the pH of the hydrochloric acid pickling liquor is 1.0 - 4.5. Thus, the impurity element chlorine in the zinc ash can be dissolved into the liquid phase, making the impurity element chlorine in the zinc dross well removed and avoiding adverse effects on the hydrometallurgical zinc system.

[0028] In some embodiments of the present invention, in step (4), the solid-liquid ratio of the zinc ash to the hydrochloric acid pickling liquor is 1 g : (3 - 10) mL. Thus, on the one hand, it can ensure sufficient pickling of the zinc ash and make the impurity element chlorine well removed; on the other hand, it can avoid causing a large load on the subsequent first solid-liquid separation and evaporation crystallization processes.

[0029] In some embodiments of the present invention, in step (4), the temperature of the hydrochloric acid pickling liquor is 50 - 80 °C, and the pickling time is 0.5 - 5 h. Thus, a certain pickling efficiency and pickling effect can be ensured.

[0030] In some embodiments of the present invention, the above method further includes: (7) supplying the massive zinc obtained in step (1) and the zinc particles obtained in step (2) to a forming device to obtain pellets, and supplying the pellets to a zinc melting furnace for zinc recovery. Thereby, it facilitates storage and transportation, reduces losses during the recycling process, and improves the zinc recovery rate.

[0031] In some embodiments of the present invention, the above method further includes: (8) supplying the pickling filter residue to contact with a washing liquid in a washing device to obtain a post-washing liquid; (9) supplying the post-washing liquid to a second solid-liquid separation device for treatment to obtain a washing filtrate and a washing filter residue, supplying the washing filtrate to step (4) as the hydrochloric acid washing liquid, and supplying the washing filter residue to the zinc leaching process of the wet process system as a zinc chloride raw material. Thereby, the production cost is saved and the zinc recovery rate is improved.

[0032] In some embodiments of the present invention, in step (8), the solid-liquid ratio of the pickling filter residue to the washing liquid is 1 g : (3 - 10) mL. Thereby, on the one hand, it can ensure sufficient washing of the pickling filter residue; on the other hand, it can avoid causing a large load on the subsequent second solid-liquid separation process.

[0033] In some embodiments of the present invention, in step (8), the temperature of the washing liquid is 50 - 80 °C and the washing time is 0.5 - 5 h. Thereby, a certain washing efficiency and washing effect can be ensured.

[0034] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Description of the Drawings

[0035] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0036] Figure 1 is a schematic structural diagram of a system for comprehensively treating zinc dross according to an embodiment of the present invention;

[0037] Figure 2 is a schematic structural diagram of a system for comprehensively treating zinc dross according to another embodiment of the present invention;

[0038] Figure 3 is a schematic structural diagram of a system for comprehensively treating zinc dross according to another embodiment of the present invention;

[0039] Figure 4 is a schematic structural diagram of a system for comprehensively treating zinc dross according to another embodiment of the present invention;

[0040] Figure 5 It is a schematic flow diagram of a method for comprehensively treating zinc dross by using the above system according to an embodiment of the present invention;

[0041] Figure 6 It is a schematic flow diagram of a method for comprehensively treating zinc dross by using the above system according to another embodiment of the present invention;

[0042] Figure 7 It is a schematic process flow diagram of a method for comprehensively treating zinc dross by using the above system according to an embodiment of the present invention. Detailed implementation manners

[0043] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation of the present invention.

[0044] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0045] In the present invention, unless otherwise clearly specified and defined, the terms "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In one aspect of the present invention, the present invention provides a system for comprehensively treating zinc dross. According to an embodiment of the present invention, referring to Figure 1 , the system includes: a screening device 100, a ball mill 200, a powder-ash separation unit 300, a pickling device 400, a first solid-liquid separation device 500, and an evaporation crystallization device 600.

[0047] According to an embodiment of the present invention, the screening device 100 has a zinc dross inlet 11, a massive zinc outlet 12 and an undersize outlet 13, and is adapted to supply zinc dross into the screening device 100 for screening treatment to separate massive zinc and undersize containing zinc particles and zinc powder ash. Specifically, the separation principle of the screening device 100 is as follows: by utilizing the relative movement between the granular material and the screen surface, zinc particles and zinc powder ash smaller than the screen hole size pass through the screen holes, while massive zinc larger than the screen hole size is continuously discharged from the massive zinc outlet, so that the massive zinc is first separated from the zinc dross. It should be noted that those skilled in the art can select the specific type of the screening device 100 according to actual needs as long as the above functions can be achieved.

[0048] According to an embodiment of the present invention, the ball mill 200 has an undersize inlet 21, a zinc particle outlet 22 and a zinc powder ash outlet 23. The undersize inlet 21 is connected to the undersize outlet 13 and is adapted to supply zinc particles and zinc powder ash into the ball mill 200 for ball milling under a suitable negative pressure environment, and perform air separation according to the mass difference between the zinc particles and the zinc powder ash to separate the zinc particles and the zinc powder ash, and discharge the zinc particles from the zinc particle outlet, so that the zinc particles are separated from the zinc dross. Preferably, the above suitable negative pressure environment is achieved by adjusting the frequency of a centrifugal fan (not shown). It should be noted that those skilled in the art can select the specific types of the ball mill 200 and the centrifugal fan according to actual needs as long as the above functions can be achieved.

[0049] According to an embodiment of the present invention, the powder ash separation unit 300 has a zinc powder ash inlet 31, a zinc powder outlet 32 and a zinc ash outlet 33. The zinc powder ash inlet 31 is connected to the zinc powder ash outlet 23 and is adapted to supply zinc powder ash into the powder ash separation unit 300 to separate zinc powder and zinc ash. It should be noted that those skilled in the art can select the specific type of the powder ash separation unit 300 according to actual needs as long as the above functions can be achieved.

[0050] Further, referring to Figure 2 , the powder ash separation unit 300 includes a cyclone dust collector 301 and a bag filter 302 connected in sequence. Under the action of the cyclone dust collector 301, zinc powder is collected in the cyclone dust collector 301, while the lighter zinc ash finally enters the bag filter 302. It should be noted that those skilled in the art can select the specific types of the cyclone dust collector 301 and the bag filter 302 according to actual needs as long as the above functions can be achieved.

[0051] According to an embodiment of the present invention, the pickling device 400 has a zinc ash inlet 41, a hydrochloric acid pickling solution inlet 42, and a pickled solution outlet 43. The zinc ash inlet 41 is connected to the zinc ash outlet 33 and is adapted to supply zinc ash to the pickling device 400 to contact with the hydrochloric acid pickling solution for pickling to obtain a pickled solution. The inventor found that in zinc ash, zinc is mainly zinc oxide, and the impurity element chlorine exists in the form of Zn 5 (OH) 8 Cl 2 ·2H 2 O. Almost all of the Zn 5 (OH) 8 Cl 2 ·2H 2 O and part of zinc oxide can react with the hydrochloric acid pickling solution to form zinc chloride and enter the liquid phase, so that the impurity element chlorine is well removed, avoiding adverse effects on the hydrometallurgical zinc system. It should be noted that those skilled in the art can select the specific type of the pickling device 400 according to actual needs as long as the above functions can be achieved. Preferably, the pH of the hydrochloric acid pickling solution is 1.0 - 4.5; the solid-liquid ratio of zinc ash to the hydrochloric acid pickling solution is 1 g:(3 - 10) mL; the temperature of the hydrochloric acid pickling solution is 50 - 80 °C, and the pickling time is 0.5 - 5 h.

[0052] According to an embodiment of the present invention, the first solid-liquid separation device 500 has a pickled solution inlet 51, a pickling filtrate outlet 53, and a pickling filter residue outlet 52. The pickled solution inlet 51 is connected to the pickled solution outlet 43 and is adapted to supply the pickled solution to the first solid-liquid separation device 500 for solid-liquid separation to obtain a pickling filtrate and a pickling filter residue. It should be noted that those skilled in the art can select the specific type of the first solid-liquid separation device 500 according to actual needs as long as the above functions can be achieved.

[0053] According to an embodiment of the present invention, the evaporation crystallization device 600 has a pickling filtrate inlet 61, an evaporated water outlet 63, and a zinc chloride crystal outlet 62. The pickling filtrate inlet 61 is connected to the pickling filtrate outlet 53 and is adapted to supply the pickling filtrate to the evaporation crystallization device 600 for evaporation, concentration, and drying to obtain evaporated water and zinc chloride crystals. It should be noted that those skilled in the art can select the specific type of the evaporation crystallization device 600 according to actual needs as long as the above functions can be achieved.

[0054] The inventors found that by feeding zinc dross to a screening device for preliminary screening, massive zinc and undersize materials containing zinc particles and zinc ash powder are separated, so that massive zinc can be separated from the zinc dross first. The undersize materials containing zinc particles and zinc ash powder are fed to a ball mill under a negative pressure environment for ball milling to separate zinc particles and zinc powder ash, so that zinc particles can be continuously separated from the zinc dross. Then, the zinc powder ash is fed to a powder ash separation unit to separate zinc powder and zinc ash, and the zinc ash is fed to a pickling device to contact with hydrochloric acid pickling solution for pickling. The pickled solution obtained is fed to a first solid-liquid separation device for first solid-liquid separation to obtain pickling filtrate and pickling filter residue. Finally, the pickling filtrate is fed to an evaporation crystallization device for treatment to obtain evaporated water and zinc chloride crystals. Using this system to comprehensively treat zinc dross can thoroughly separate each material component in the zinc dross, significantly improve the zinc recovery rate (the zinc recovery rate is as high as over 99%), and has a simple process flow, convenient operation, low energy consumption, and environmental friendliness. In addition, the impurity element chlorine in the zinc dross is well removed, avoiding adverse effects on the hydrometallurgical zinc system. The zinc chloride obtained by evaporation crystallization of the pickling filtrate can also be sold as a product, having good economic benefits and environmental emission reduction benefits.

[0055] Further, referring to Figures 3-4 , the above-mentioned system for comprehensively treating zinc dross further includes a forming device 700, a water washing device 800, and a second solid-liquid separation device 900.

[0056] According to an embodiment of the present invention, referring to Figure 3 , the forming device 700 has a massive zinc inlet 71, a zinc particle inlet 72, and a pellet outlet 73. The massive zinc inlet 71 is connected to the massive zinc outlet 12, and the zinc particle inlet 72 is connected to the zinc particle outlet 22, and is adapted to feed massive zinc and zinc particles to the forming device 700 respectively for pellet forming and then return to the zinc melting furnace to recover zinc, thereby improving the zinc recovery rate. It should be noted that those skilled in the art can select the specific type of the forming device 700 according to actual needs as long as the above functions can be achieved.

[0057] According to an embodiment of the present invention, referring to Figure 4 , the water washing device 800 has a pickling filter residue inlet 81, a water washing liquid inlet 82, and a post-water washing liquid outlet 83. The pickling filter residue inlet 81 is connected to the pickling filter residue outlet 52, and is adapted to feed the pickling filter residue to the water washing device 800 for water washing. The water-washed filter residue is fed to the zinc leaching process of the hydrometallurgical system as a zinc-containing raw material, thereby improving the zinc recovery rate. It should be noted that those skilled in the art can select the specific type of the water washing device 800 according to actual needs as long as the above functions can be achieved. Preferably, the temperature of the water washing liquid is 50 - 80 °C, and the water washing time is 0.5 - 5 h.

[0058] According to an embodiment of the present invention, with reference to Figure 4 , the second solid-liquid separation device 900 has a post-washing liquid inlet 91, a post-washing filtrate outlet 93 and a post-washing filter residue outlet 92. The post-washing liquid inlet 91 is connected to the post-washing liquid outlet 83, and the post-washing filtrate outlet 93 is connected to the hydrochloric acid washing liquid inlet 42. It is adapted to supply the post-washing liquid into the second solid-liquid separation device 900 for the second solid-liquid separation, and return the obtained post-washing filtrate to the pickling process, thereby saving the production cost. It should be noted that those skilled in the art can select the specific type of the second solid-liquid separation device 900 according to actual needs as long as the above functions can be achieved.

[0059] In the second aspect of the present invention, the present invention proposes a method for comprehensively treating zinc dross by using the above system, with reference to Figure 5 , the method includes:

[0060] S100: Supply the zinc dross to a screening device for screening

[0061] In this step, by supplying the zinc dross to a screening device for screening, massive zinc and the undersize material containing zinc particles and zinc powder ash can be separated. Specifically, the separation principle of this screening device is: by using the relative movement between the granular material and the screen surface, the zinc particles and zinc powder ash smaller than the screen hole size pass through the screen holes, while the massive zinc larger than the screen hole size is continuously discharged from the massive zinc outlet, so that the massive zinc is first separated from the zinc dross.

[0062] S200: Under a negative pressure environment, supply the undersize material containing zinc particles and zinc powder ash to a ball mill for ball milling

[0063] In this step, by supplying the undersize material containing zinc particles and zinc powder ash to a ball mill for ball milling under a suitable negative pressure environment, air separation is carried out according to the mass difference between the zinc particles and zinc powder ash, the zinc particles and zinc powder ash are separated, and the zinc particles are discharged from the zinc particle outlet, so that the zinc particles are separated from the zinc dross. Preferably, the above suitable negative pressure environment is achieved by adjusting the frequency of the centrifugal fan.

[0064] S300: Supply the zinc powder ash to the powder-ash separation unit

[0065] In this step, by supplying the zinc powder ash to the powder-ash separation unit, zinc powder and zinc ash can be separated. Specifically, the powder-ash separation unit includes a cyclone dust collector and a bag filter connected in sequence. Under the action of the cyclone dust collector, the zinc powder is collected in the cyclone dust collector, and the lighter zinc ash finally enters the bag filter. Further, the zinc powder is supplied to the purification process of the main system as an auxiliary material.

[0066] S400: Supply the zinc ash to the pickling device to contact with the hydrochloric acid washing liquid

[0067] In this step, pickling is carried out by supplying zinc ash to a pickling device to contact with hydrochloric acid pickling solution, and pickled solution can be obtained. The inventor found that in zinc ash, zinc is mainly zinc oxide, and the impurity element chlorine exists in the form of Zn 5 (OH) 8 Cl 2 ·2H 2 O. Almost all of the Zn 5 (OH) 8 Cl 2 ·2H 2 O and part of zinc oxide can react with hydrochloric acid pickling solution to generate zinc chloride and enter the liquid phase, so that the impurity element chlorine is well removed, avoiding adverse effects on the hydrometallurgical zinc system.

[0068] Furthermore, the pH of the hydrochloric acid pickling solution is 1.0 - 4.5, preferably 3.5 - 4.5. The inventor found that the greater the acidity of the hydrochloric acid pickling solution, the higher the removal rate of chlorine in zinc ash. However, too high acidity may dissolve a large amount of zinc oxide, reducing the zinc recovery rate. At the same time, it will also corrode the equipment, cause crystallization and block the pipeline.

[0069] Furthermore, the solid-liquid ratio of the zinc ash to the hydrochloric acid pickling solution is 1g:(3 - 10)mL, preferably 1g:(3 - 4)mL. The inventor found that if the solid-liquid ratio is too large, the zinc ash and the hydrochloric acid pickling solution cannot be fully contacted, resulting in more impurity element chlorine remaining in the zinc ash and unable to dissolve into the liquid phase. The zinc ash contains chlorine and returns to the fluidized bed furnace for batching. The flue gas contains high chlorine, corrodes the equipment and is not friendly to the environment. If the solid-liquid ratio is too small, it will cause a large load on the subsequent first solid-liquid separation and evaporation crystallization processes, and increase the production cost.

[0070] Furthermore, the temperature of the hydrochloric acid pickling solution is 50 - 80°C, preferably 60 - 70°C, and the pickling time is 0.5 - 5h, preferably 2 - 3h. The inventor found that if the temperature of the hydrochloric acid pickling solution is too low, the pickling efficiency will be reduced; if the temperature of the hydrochloric acid pickling solution is too high, the energy consumption will increase. If the pickling time is too short, the zinc ash cannot be fully pickled, resulting in more impurity element chlorine remaining in the zinc ash and unable to dissolve into the liquid phase. The zinc ash contains chlorine and returns to the fluidized bed furnace for batching. The flue gas contains high chlorine, corrodes the equipment and is not friendly to the environment. If the pickling time is too long, the production efficiency will be reduced.

[0071] S500: Supply the pickled solution to a first solid-liquid separation device for treatment

[0072] In this step, by supplying the pickled solution to a first solid-liquid separation device for solid-liquid separation, pickled filtrate and pickled filter residue can be obtained.

[0073] S600: Supply the pickling filtrate to an evaporation crystallization device for treatment

[0074] In this step, by supplying the pickling filtrate to the evaporation crystallization device for evaporation, concentration, and drying, evaporation water and zinc chloride crystals can be obtained, and the prepared zinc chloride can be sold as a product externally.

[0075] The inventor found that by supplying zinc dross to a screening device for preliminary screening, massive zinc and undersize materials containing zinc particles and zinc ash powder are separated, so that the massive zinc can be separated from the zinc dross first. The undersize materials containing zinc particles and zinc ash powder are supplied to a ball mill under a negative pressure environment for ball milling to separate zinc particles and zinc powder ash, so that the zinc particles can be continuously separated from the zinc dross. Then, the zinc powder ash is supplied to a powder ash separation unit to separate zinc powder and zinc ash, and the zinc ash is supplied to a pickling device to contact with a hydrochloric acid washing solution for pickling. The pickled solution obtained is supplied to a first solid-liquid separation device for first solid-liquid separation to obtain a pickling filtrate and pickling filter residue. Finally, the pickling filtrate is supplied to an evaporation crystallization device for treatment to obtain evaporation water and zinc chloride crystals. Using this method for comprehensive treatment of zinc dross enables thorough separation of each material component in the zinc dross, significantly improves the zinc recovery rate (the zinc recovery rate is as high as over 99%), and has a simple process flow, is easy to operate, has low energy consumption, and is environmentally friendly. In addition, the impurity element chlorine in the zinc dross is well removed, avoiding adverse effects on the hydrometallurgical zinc system. The zinc chloride obtained by evaporation crystallization of the pickling filtrate can also be sold as a product externally, having good economic benefits and environmental emission reduction benefits.

[0076] Furthermore, referring to Figures 6-7 , the method for comprehensively treating zinc dross using the above system further includes:

[0077] S700: Supply the massive zinc obtained in step S100 and the zinc particles obtained in step S200 to a forming device, and supply the obtained pellets to a zinc melting furnace to recover zinc

[0078] In this step, by supplying the massive zinc obtained in step S100 and the zinc particles obtained in step S200 to a forming device, the massive zinc or zinc particles can be pressed into pellets to facilitate storage, transportation, and reduce losses during the recycling process; and the obtained pellets are supplied to a zinc melting furnace to recover zinc, thereby improving the zinc recovery rate.

[0079] S800: Supply the pickling filter residue to a water washing device to contact with a water washing solution

[0080] In this step, by supplying the pickling filter residue obtained in step S500 to a water washing device to contact with a water washing solution for water washing, a post-washing solution is obtained. The inventor found that the chlorine removal rate can be further improved through the water washing process.

[0081] Further, the solid-liquid ratio of the pickling filter residue to the water washing liquid is 1 g:(3-10) mL, preferably 1 g:(6-8) mL. The inventors found that if the solid-liquid ratio is too high, the water washing will be insufficient, and the pickling filter residue still contains a certain amount of impurity element chlorine. When it is returned to the boiling furnace for batching, the flue gas contains a high amount of chlorine, which corrodes the equipment and is not environmentally friendly. If the solid-liquid ratio is too small, it will cause a large load on the subsequent second solid-liquid separation process and increase the production cost.

[0082] Further, the temperature of the water washing liquid is 50-80 °C, preferably 50-60 °C, and the water washing time is 0.5-5 h, preferably 0.5-1 h. The inventors found that if the water washing temperature is too low, the water washing efficiency will be reduced; if the water washing temperature is too high, the energy consumption will increase. If the water washing time is too short, the water washing will be insufficient; if the water washing time is too long, the production efficiency will be reduced.

[0083] S900: Supply the post-water washing liquid to a second solid-liquid separation device for treatment, supply the obtained water washing filtrate to step S400 as the hydrochloric acid washing liquid, and supply the obtained water washing filter residue to the zinc leaching process of the hydrometallurgical system as the zinc chloride raw material.

[0084] In this step, by supplying the post-water washing liquid to a second solid-liquid separation device for treatment, the water washing filtrate and the water washing filter residue can be separated. The obtained water washing filtrate is supplied to step S400 as the hydrochloric acid washing liquid, so that the water washing filtrate is recycled, saving the production cost; the obtained water washing filter residue is supplied to the zinc leaching process of the hydrometallurgical system as the zinc chloride raw material, thereby improving the zinc recovery rate.

[0085] Next, the solution of the present invention will be explained with reference to the examples. Those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. For those not specified in the examples regarding specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For the reagents or instruments not specified as the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0086] Example 1

[0087] Step 1: Take 5000 Kg of zinc dross (the larger lumps of zinc have been picked out), naturally cool it to below 60 °C, turn on the centrifugal fan of the bag filter, adjust the air volume to 25000-30000 Nm 3 / h, and slowly and evenly add the zinc dross to the silo. After screening by a linear vibrating screen, lumpy zinc and the undersize containing zinc particles and zinc powder ash are obtained. The lumpy zinc enters the slag hopper from the chute.

[0088] Step 2: Feed the screen undersize containing zinc particles and zinc powder ash to a ball mill for grinding, and separate to obtain zinc particles and zinc powder ash. The zinc particles are discharged from the zinc particle outlet of the ball mill and enter the slag hopper.

[0089] Step 3: Discharge the zinc powder and zinc ash from the zinc powder ash outlet of the ball mill into the dust collection pipeline. Due to the difference in mass, the zinc powder enters the cyclone dust collector for collection, and the zinc ash enters the bag filter for collection. Finally, 265 Kg of lumpy zinc (50 mm < particle size ≤ 200 mm), 747 Kg of zinc particles (80 mesh < particle size ≤ 50 mm), 310 Kg of zinc powder (particle size ≤ 80 mesh), and 3670 Kg of zinc ash (particle size ≤ 100 mesh) are produced.

[0090] Step 4: Feed the zinc ash to an acid pickling tank for pulping and acid pickling. The pH of the hydrochloric acid washing solution is 4.5, the liquid-solid ratio is controlled at 4 m 3 / t, the acid pickling temperature is 60 °C. After acid pickling for 1 h, the pickled solution is obtained.

[0091] Step 5: Filter press the pickled solution to obtain pickled filtrate and pickled filter residue. Among them, the pickled filtrate contains 2.55 g / L of zinc, 3.16 g / L of chlorine, and pH ~ 5.0.

[0092] Step 6: Evaporate, concentrate, and dry the pickled filtrate to produce 72.45 Kg of zinc chloride with a purity of 99.65%.

[0093] Step 7: Feed the lumpy zinc obtained in step (1) and the zinc particles obtained in step (2) to a cake press for briquetting and then to a zinc melting furnace.

[0094] Step 8: Feed the pickled filter residue obtained in step (5) to a water washing tank for pulping and water washing. The liquid-solid ratio is controlled at 4 m 3 / t, the water washing temperature is 60 °C. After water washing for 1 h, the washed solution is obtained.

[0095] Step 9: Filter press the washed solution to obtain washed filtrate and washed filter residue, and return the washed filtrate to the acid pickling process. The washed filter residue is pulped with a leaching agent and then enters the zinc leaching process of the hydrometallurgical system. The washed zinc oxide contains 0.0055% of chlorine.

[0096] Example 2

[0097] Step 1: Take 5000 Kg of zinc dross (the larger lumpy zinc has been picked out), naturally cool it to below 60 °C, start the centrifugal fan of the bag filter, adjust the air volume to 25000 - 30000 Nm 3 / h, and slowly and evenly add the zinc dross to the bunker. After screening by a linear vibrating screen, lumpy zinc and screen undersize containing zinc particles and zinc powder ash are obtained. The lumpy zinc enters the slag hopper through the chute.

[0098] Step 2: Feed the screen undersize containing zinc particles and zinc powder ash to a ball mill for grinding, separate to obtain zinc particles and zinc powder ash, and discharge the zinc particles from the zinc particle outlet of the ball mill into a slag hopper;

[0099] Step 3: Discharge the zinc powder and zinc ash from the zinc powder ash outlet of the ball mill into a dust collection pipeline. Due to the mass difference, the zinc powder enters a cyclone dust collector for collection, and the zinc ash enters a bag filter for collection. Finally, 186 Kg of massive zinc (50 mm < particle size ≤ 200 mm), 803 Kg of zinc particles (80 mesh < particle size ≤ 50 mm), 361 Kg of zinc powder (particle size ≤ 80 mesh), and 3635 Kg of zinc ash (particle size ≤ 100 mesh) are produced;

[0100] Step 4: Feed the zinc ash to a pickling tank for pulping and pickling. The pH of the hydrochloric acid pickling solution is 3.5, control the liquid-solid ratio to be 3 m 3 / t, the pickling temperature is 70 °C. After pickling for 0.5 h, pickled solution is obtained;

[0101] Step 5: Filter press the pickled solution to obtain pickled filtrate and pickled filter residue. Among them, the pickled filtrate contains 4.85 g / L of zinc, 6.24 g / L of chlorine, and pH ~ 5.0;

[0102] Step 6: Evaporate, concentrate, and dry the pickled filtrate to produce 101.17 Kg of zinc chloride with a purity of 99.83%;

[0103] Step 7: Feed the massive zinc obtained in step (1) and the zinc particles obtained in step (2) to a cake press to form pellets and then feed them to a zinc melting furnace;

[0104] Step 8: Feed the pickled filter residue obtained in step (5) to a water washing tank for pulping and water washing. Control the liquid-solid ratio to be 5 m 3 / t, the water washing temperature is 60 °C. After water washing for 1 h, water washed solution is obtained;

[0105] Step 9: Filter press the water washed solution to obtain water washed filtrate and water washed filter residue, and return the water washed filtrate to the pickling process. Pulp the water washed filter residue with a leaching agent and then enter the zinc leaching process of the hydrometallurgical system. The zinc oxide after water washing contains 0.0063% of chlorine.

[0106] Example 3

[0107] Step 1: Take 5000 Kg of zinc dross (the larger massive zinc has been picked out), naturally cool it to below 60 °C, start the centrifugal fan of the bag filter, adjust the air volume to 25000 - 30000 Nm 3 / h, and uniformly and slowly add the zinc dross to the silo. After screening by a linear vibrating screen, massive zinc and screen undersize containing zinc particles and zinc powder ash are obtained. The massive zinc enters the slag hopper through a chute;

[0108] Step 2: Feed the undersize material containing zinc particles and zinc powder ash to a ball mill for grinding, and separate to obtain zinc particles and zinc powder ash. The zinc particles are discharged from the zinc particle outlet of the ball mill and enter the slag hopper.

[0109] Step 3: Discharge the zinc powder and zinc ash from the zinc powder ash outlet of the ball mill into the dust collection pipeline. Due to the mass difference, the zinc powder enters the cyclone dust collector for collection, and the zinc ash enters the bag filter for collection. Finally, 220 Kg of massive zinc (50 mm < particle size ≤ 200 mm), 659 Kg of zinc particles (80 mesh < particle size ≤ 50 mm), 382 Kg of zinc powder (particle size ≤ 80 mesh), and 3728 Kg of zinc ash (particle size ≤ 100 mesh) are produced.

[0110] Step 4: Feed the zinc ash to an acid pickling tank for pulping and pickling. The pH of the hydrochloric acid pickling solution is 4.0, the liquid-solid ratio is controlled at 5 m 3 / t, the pickling temperature is 50 °C. After pickling for 1.5 h, pickled solution is obtained.

[0111] Step 5: Filter press the pickled solution to obtain pickled filtrate and pickled filter residue. Among them, the pickled filtrate contains 3.25 g / L of zinc, 4.07 g / L of chlorine, and pH ~ 5.0.

[0112] Step 6: Evaporate, concentrate, and dry the pickled filtrate to produce 116.24 Kg of zinc chloride with a purity of 99.70%.

[0113] Step 7: Feed the massive zinc obtained in step (1) and the zinc particles obtained in step (2) to a briquetting machine for briquetting and then to a zinc melting furnace.

[0114] Step 8: Feed the pickled filter residue obtained in step (5) to a water washing tank for pulping and water washing. The liquid-solid ratio is controlled at 4 m 3 / t, the water washing temperature is 65 °C. After water washing for 0.5 h, water washed solution is obtained.

[0115] Step 9: Filter press the water washed solution to obtain water washed filtrate and water washed filter residue, and return the water washed filtrate to the pickling process. The water washed filter residue is pulped with a leaching agent and then enters the zinc leaching process of the hydrometallurgical system. The zinc oxide after water washing contains 0.0085% of chlorine.

[0116] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0117] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for comprehensively treating zinc dross by using a system for comprehensively treating zinc dross, characterized in that, the system for comprehensively treating zinc dross includes: a screening device, which has a zinc dross inlet, a massive zinc outlet and an undersize outlet; a ball mill, which has an undersize inlet, a zinc particle outlet and a zinc powder ash outlet, and the undersize inlet is connected to the undersize outlet; a powder ash separation unit, which has a zinc powder ash inlet, a zinc powder outlet and a zinc ash outlet, and the zinc powder ash inlet is connected to the zinc powder ash outlet; a pickling device, which has a zinc ash inlet, a hydrochloric acid washing solution inlet and a pickled solution outlet, and the zinc ash inlet is connected to the zinc ash outlet; a first solid-liquid separation device, which has a pickled solution inlet, a pickled filtrate outlet and a pickled residue outlet, and the pickled solution inlet is connected to the pickled solution outlet; an evaporation crystallization device, which has a pickled filtrate inlet, an evaporated water outlet and a zinc chloride crystal outlet, and the pickled filtrate inlet is connected to the pickled filtrate outlet; a water washing device, which has a pickled residue inlet, a water washing solution inlet and a water washed solution outlet, and the pickled residue inlet is connected to the pickled residue outlet; a second solid-liquid separation device, which has a water washed solution inlet, a water washed filtrate outlet and a water washed residue outlet, and the water washed solution inlet is connected to the water washed solution outlet, the method includes: (1) Feeding the zinc dross to the screening device for screening treatment to separate massive zinc and undersize containing zinc particles and zinc powder ash; (2) Under a negative pressure environment, feeding the undersize containing zinc particles and zinc powder ash to the ball mill for ball milling to separate zinc particles and zinc powder ash; (3) Feeding the zinc powder ash to the powder ash separation unit to obtain separated zinc powder and zinc ash; (4) Feeding the zinc ash to the pickling device to contact with the hydrochloric acid washing solution to obtain a pickled solution; (5) Feeding the pickled solution to the first solid-liquid separation device for treatment to obtain a pickled filtrate and a pickled residue; (6) Feeding the pickled filtrate to the evaporation crystallization device for treatment to obtain evaporated water and zinc chloride crystals; (7) Feeding the pickled residue to the water washing device to contact with the water washing solution to obtain a water washed solution; (8) Feeding the water washed solution to the second solid-liquid separation device for treatment to obtain a water washed filtrate and a water washed residue, and feeding the water washed residue as a zinc-containing raw material to the zinc leaching process of the hydrometallurgical zinc system, in step (4), the pH of the hydrochloric acid washing solution is 1.0 - 4.5; in step (4), the solid-liquid ratio of the zinc ash to the hydrochloric acid washing solution is 1 g:(3 - 10) mL; in step (4), the temperature of the hydrochloric acid washing solution is 50 - 80 °C, and the pickling time is 0.5 - 5 h.

2. The method according to claim 1, characterized in that, the powder ash separation unit includes a cyclone dust collector and a bag filter connected in sequence.

3. The method according to claim 1 or 2, characterized in that, further includes: A forming device, the forming device having a bulk zinc inlet, a zinc particle inlet, and a pellet outlet, the bulk zinc inlet being connected to the bulk zinc outlet, and the zinc particle inlet being connected to the zinc particle outlet.

4. The method according to claim 1, wherein, the water washing filtrate outlet is connected to the hydrochloric acid washing solution inlet.

5. The method according to claim 1, wherein, further comprising: (9) Supplying the bulk zinc obtained in step (1) and the zinc particles obtained in step (2) to a forming device to obtain pellets, and supplying the pellets to a zinc melting furnace to recover zinc.

6. The method according to claim 1, wherein, step (8) further comprises: Supplying the water washing filtrate to step (4) as the hydrochloric acid washing solution.

7. The method according to claim 6, wherein, in step (8), the solid-liquid ratio of the pickling filter residue to the water washing solution is 1 g:(3 - 10) mL.

8. The method according to claim 6, wherein, in step (8), the temperature of the water washing solution is 50 - 80 °C, and the water washing time is 0.5 - 5 h.

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