System for separating zinc and iron in zinc hydrometallurgy

Abstract

The utility model discloses a system for separating zinc and iron in zinc hydrometallurgy, comprising: a first liquid phase treatment device for performing first heating treatment on a zinc-iron solution to obtain a heated zinc-iron solution; the reaction device is used for carrying out second heating treatment on the heated zinc-iron solution to obtain a ferrous sulfate suspension; the temperature of the second heating treatment is higher than that of the first heating treatment; the second liquid phase treatment device is used for carrying out sedimentation treatment on the ferrous sulfate suspension to obtain sedimentation liquid, and the sedimentation liquid comprises ferrous sulfate crystals. The first liquid phase treatment device can increase the temperature of the zinc-iron solution, so that the vibration of the reaction device caused by large temperature difference fluctuation is reduced; continuously heating the zinc-iron solution in the reaction device to separate out ferrous sulfate crystals; and in the second liquid phase treatment device, the ferrous sulfate suspension liquid is subjected to sedimentation treatment, sedimentation liquid containing ferrous sulfate is obtained, and the iron element in the zinc-iron solution is separated.

Description

Technical Field

[0001] This application relates to the field of metallurgical technology, and more specifically, to a system for separating zinc and iron in hydrometallurgical zinc refining. Background Technology

[0002] Hydrometallurgical refining is currently the main method for zinc smelting, and the process involves extracting zinc from zinc concentrate. Because iron and zinc ions have similar ionic radii, zinc concentrate inevitably contains iron. To obtain high-quality zinc, it is necessary to remove iron impurities from the zinc concentrate.

[0003] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Utility Model Content

[0004] In a first aspect, this application provides a system for separating zinc and iron in a hydrometallurgical zinc smelting process. The system includes: a first liquid-phase treatment device for subjecting a zinc-iron solution to a first heating treatment to obtain a heated zinc-iron solution; a reaction device for subjecting the heated zinc-iron solution to a second heating treatment to obtain a ferrous sulfate suspension; the temperature of the second heating treatment is higher than the temperature of the first heating treatment; and a second liquid-phase treatment device for subjecting the ferrous sulfate suspension to a sedimentation treatment to obtain a precipitate containing ferrous sulfate crystals. Thus, the first liquid-phase treatment device can increase the temperature of the zinc-iron solution to reduce the temperature difference between the zinc-iron solution and the reaction device, thereby reducing vibration of the reaction device caused by large temperature fluctuations; subsequently, in the reaction device, the zinc-iron solution continues to heat up to precipitate ferrous sulfate crystals; finally, in the second liquid-phase treatment device, the ferrous sulfate suspension is subjected to sedimentation treatment to obtain a precipitate containing ferrous sulfate, thereby separating the iron element from the zinc-iron solution.

[0005] In some embodiments, the reaction apparatus includes a horizontally oriented reaction vessel with multiple spaced overflow baffles within its interior cavity. These overflow baffles divide the interior cavity into multiple sub-chambers, with adjacent sub-chambers connected by notches in the overflow baffles. This division of the interior cavity into sub-chambers allows for segmented monitoring of the reaction temperature in each sub-chamber. Secondly, the overflow baffles increase the heat exchange area of ​​the zinc-iron solution, thereby improving heat exchange efficiency and increasing the rate of ferrous sulfate precipitation. Finally, the separated sub-chambers reduce the risk of sudden reactions, thus improving operational safety.

[0006] In some embodiments, the notches of the overflow baffle are symmetrically arranged with respect to the center of the sub-chamber. This symmetrical arrangement of the notches improves the uniformity of the zinc-iron solution flow within the horizontal reactor cavity, reducing dead zones or uneven flow phenomena during the process. Simultaneously, it reduces hydrodynamic instability as the zinc-iron solution flows from one sub-chamber to the next.

[0007] In some embodiments, the spacing between the overflow baffles is equal. This improves the consistency of hydrodynamic conditions within each sub-chamber, reducing localized overheating of the zinc-iron solution and ensuring a more uniform reaction.

[0008] In some embodiments, the overflow baffle is arranged perpendicular to the length of the horizontal reaction vessel. This optimizes the spatial layout of the sub-chambers and improves the effective volume utilization of the horizontal reactor.

[0009] In some embodiments, a stirring device is provided in the sub-chamber. This can increase the reaction rate.

[0010] In some embodiments, heating devices are independently provided on the inner walls of the corresponding housings of the first liquid phase treatment device, the reaction device, and the second liquid phase treatment device, and the heating devices include steam heating pipes. This allows the zinc-iron solution to be heated.

[0011] In some embodiments, the system satisfies at least one of the following conditions: (i) the heating temperature of the first heat treatment is 120°C-130°C; (ii) the operating pressure of the reaction apparatus is 0.5 MPa-1.0 MPa; and (iii) the heating temperature of the second heat treatment is 160°C-175°C. Therefore, by controlling the temperature and pressure parameters in the system, the rate of ferrous sulfate crystal precipitation can be increased, thereby improving the system's operating efficiency.

[0012] In some embodiments, the system further includes a solid-liquid separation device for performing solid-liquid separation treatment on the sediment to obtain ferrous sulfate crystals.

[0013] In some embodiments, the sedimentation process further includes obtaining a supernatant, and the system further includes a heat exchanger for recovering waste heat from the supernatant. This allows for the reuse of thermal energy, thereby reducing energy consumption.

[0014] In some embodiments, the first liquid phase treatment device and the second liquid phase treatment device have the same structure. After a period of use, ferrous sulfate crystals gradually adhere to the inner wall of the system, forming scale. This scale reduces the system's low heat exchange efficiency and reaction rate. The first and second liquid phase treatment devices of this application are interchangeable. Thus, the zinc-iron solution enters the system from the second liquid phase treatment device; that is, the lower-temperature zinc-iron solution enters the second liquid phase treatment device, causing the ferrous sulfate deposited on the inner wall of the second liquid phase treatment device to redissolve in the low-temperature zinc-iron solution. This solves the problem of poor system operation and reduced reaction rate caused by scaling. Attached Figure Description

[0015] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0016] Figure 1 This is a schematic diagram of the system for separating zinc and iron in a hydrometallurgical zinc refining process according to one embodiment of this application.

[0017] Explanation of reference numerals in the attached figures:

[0018] 1. Liquid inlet buffer vessel; 11. First liquid inlet pipe; 12. Third shut-off valve; 13. Fourth shut-off valve; 2. Horizontal reactor; 21. First pipeline; 22. Overflow baffle; 23. Notch; 24. Sub-chamber; 25. Stirring device; 26. Second pipeline; 3. Liquid-solid settling vessel; 31. Second liquid inlet pipe; 32. First shut-off valve; 33. Second shut-off valve; 4. Pressure filtration device; 41. First bottom drain pipe; 42. First pressure reducing valve; 43. Second bottom drain pipe; 44. Second pressure reducing valve; 5. Flash evaporator; 51. First top drain pipe; 52. Flash valve; 53. Second top drain pipe. Detailed Implementation

[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein 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 only used to explain this application, and should not be construed as limiting this application.

[0020] Hydrometallurgical zinc refining mainly includes five key stages: roasting, leaching, purification, electrowinning, and casting. In the leaching stage, based on different methods, it can be divided into three main categories: conventional leaching, hot acid leaching, and direct leaching. For the treatment of iron ore roasting, neutral leaching is the first step in both conventional and hot acid leaching methods. In the neutral leaching stage, ZnO in the zinc concentrate reacts with H₂SO₄, causing zinc to be converted to ZnO. 2+Iron ions are free in the leachate in the form of free radicals; however, other impurity ions also enter the leachate during this process. To improve the quality of the leachate, hydrolysis precipitation is required to convert iron ions and other impurity ions into precipitates, allowing these impurity elements to enter the intermediate leaching residue. However, during the hydrolysis precipitation process, some zinc elements also enter the intermediate leaching residue, resulting in a zinc content in the residue that is still as high as 15%-20% by mass.

[0021] To recover zinc from intermediate leaching residue, pyrometallurgical or hydrometallurgical processes are typically employed. A representative pyrometallurgical process is the rotary kiln volatilization method, which effectively recovers zinc. It utilizes the high-temperature volatility of zinc, using a reduction reaction to release zinc from dust, followed by enrichment and recovery. However, the rotary kiln volatilization method generates low-concentration sulfur dioxide flue gas, requiring additional flue gas treatment measures and significantly increasing production costs.

[0022] Hydrometallurgical processes, such as reductive leaching, can also effectively dissolve zinc from the intermediate leaching residue. Hydrometallurgical processes typically do not produce harmful gas emissions, making them more environmentally friendly. However, during this process, iron in the intermediate leaching residue is also leached out again, leading to an increase in the iron content in the leachate, ultimately resulting in a solution containing Zn. 2+ and Fe 2+ The zinc-iron solution requires further processing to separate and recover the iron and zinc.

[0023] In a first aspect of this application, a system for separating zinc and iron in a hydrometallurgical zinc smelting process is provided. The system includes: a first liquid phase treatment device for subjecting a zinc-iron solution to a first heating treatment to obtain a heated zinc-iron solution; a reaction device for subjecting the heated zinc-iron solution to a second heating treatment to obtain a ferrous sulfate suspension; the temperature of the second heating treatment is higher than the temperature of the first heating treatment; and a second liquid phase treatment device for subjecting the ferrous sulfate suspension to a sedimentation treatment to obtain a precipitate containing ferrous sulfate crystals.

[0024] Therefore, the first liquid phase treatment device can increase the temperature of the zinc-iron solution to reduce the temperature difference between the zinc-iron solution and the reaction device, thereby reducing the vibration of the reaction device caused by large temperature fluctuations; then, in the reaction device, the zinc-iron solution continues to be heated to precipitate ferrous sulfate crystals; finally, in the second liquid phase treatment device, the ferrous sulfate suspension is subjected to sedimentation treatment to obtain a precipitate containing ferrous sulfate, so as to separate the iron element in the zinc-iron solution.

[0025] As an example, combined Figure 1 The first liquid phase treatment device includes a liquid inlet buffer vessel 1. A first liquid inlet pipe 11 is provided on the wall of the liquid inlet buffer vessel 1, which is used to introduce zinc-iron solution into the liquid inlet buffer vessel 1.

[0026] In some embodiments, the zinc-iron solution includes free Zn. 2+ and Fe 2+ .

[0027] In some embodiments, a heating device is provided on the inner wall of the housing corresponding to the first liquid phase processing device. As an example, a steam heating pipe is provided on the inner wall of the inlet buffer vessel 1. The steam heating pipe is used to heat the zinc-iron solution.

[0028] In some embodiments, the heating temperature of the first heat treatment is 120°C-130°C.

[0029] As an example, the heating temperature of the first heating treatment can be 120℃, 121℃, 122℃, 123℃, 124℃, 125℃, 126℃, 127℃, 128℃, 129℃ or 130℃.

[0030] In some implementations, the reaction apparatus includes a horizontal reaction vessel with multiple spaced overflow baffles 22 within its interior cavity. These baffles divide the cavity into multiple sub-chambers 24, with adjacent sub-chambers 24 connected by notches 23 in the overflow baffles 22. This division of the cavity into sub-chambers 24 by the overflow baffles 22 allows for segmented monitoring of the reaction temperature in each sub-chamber 24. Furthermore, the overflow baffles 22 increase the heat exchange area of ​​the zinc-iron solution, thereby improving heat exchange efficiency and increasing the rate of ferrous sulfate precipitation. Finally, the separated sub-chambers 24 reduce the risk of sudden reactions, improving operational safety. It is understood that the number of sub-chambers 24 can be increased or decreased depending on the actual reaction conditions.

[0031] As an example, combined Figure 1 The horizontal reaction vessel includes a horizontal reactor 2, which is connected to a liquid inlet buffer vessel 1 via a first pipe 21. One end of the first pipe 21 is connected to the head of the horizontal reactor 2, and the other end is connected to the wall of the liquid inlet buffer vessel 1. The heated zinc-iron solution enters the horizontal reactor 2 through the first pipe 21.

[0032] Combination Figure 1 The horizontal reactor 2 has multiple overflow baffles 22 arranged at intervals inside its cavity. In this embodiment, there are 6 overflow baffles 22. Correspondingly, the horizontal reactor 2 has 7 sub-chambers 24.

[0033] In some embodiments, the notch 23 of the overflow baffle 22 is symmetrically arranged with respect to the center of the sub-chamber 24. This symmetrical arrangement of the notch 23 improves the uniformity of the zinc-iron solution flow within the horizontal reactor 2, reducing dead zones or uneven flow phenomena during the process. Simultaneously, it reduces hydrodynamic instability as the zinc-iron solution flows from one sub-chamber 24 to the next. As an example, combined with… Figure 1 The overflow baffle 22 closest to the liquid inlet buffer vessel 1 is the first overflow baffle. The notch 23 of the first overflow baffle is located near the support of the horizontal reactor 2, and the notch 23 of the overflow baffle 22 adjacent to it is located away from the support of the horizontal reactor 2.

[0034] In some embodiments, the spacing between the overflow baffles 22 is equal. This improves the consistency of the hydrodynamic conditions within each sub-chamber 24, thereby reducing localized overheating of the zinc-iron solution and ensuring a more uniform reaction.

[0035] In some embodiments, the overflow baffle 22 is arranged perpendicular to the length of the horizontal reaction vessel. This optimizes the spatial layout of each sub-chamber 24 and improves the effective volume utilization of the horizontal reactor 2.

[0036] In some embodiments, a stirring device 25 is provided inside the sub-chamber 24. This can increase the reaction rate.

[0037] In some embodiments, a heating device is provided on the inner wall of the corresponding shell of the reaction apparatus. As an example, a steam heating pipe is provided on the inner wall of the horizontal reaction vessel 2. The steam heating pipe is used to reheat the zinc-iron solution to cause ferrous sulfate crystals to precipitate from the zinc-iron solution.

[0038] In some embodiments, the heating temperature of the second heat treatment is 160°C-175°C. Therefore, by controlling the temperature of the second heat treatment, the rate of ferrous sulfate crystal precipitation can be increased, thereby improving the system's operating efficiency.

[0039] As an example, the heating temperature of the second heating treatment can be 160℃, 161℃, 162℃, 163℃, 164℃, 165℃, 166℃, 167℃, 168℃, 169℃, 170℃, 171℃, 172℃, 173℃, 174℃ or 175℃.

[0040] In some embodiments, the operating pressure of the reaction apparatus is 0.5 MPa-1.0 MPa. Therefore, by controlling the operating pressure of the reaction apparatus, the rate of ferrous sulfate crystal precipitation can be increased, thereby improving the system's operating efficiency.

[0041] As an example, the operating pressure of the reaction device can be 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa or 1.0 MPa.

[0042] As an example, combined Figure 1 The second liquid-phase treatment device includes a liquid-solid settling tank 3. The horizontal reactor 2 and the liquid-solid settling tank 3 are connected by a second pipeline 26. One end of the second pipeline 26 is connected to the head of the horizontal reactor 2, and the other end is connected to the wall of the liquid-solid settling tank 3. Ferrous sulfate suspension enters the liquid-solid settling tank 3 through the second pipeline 26. The ferrous sulfate suspension undergoes settling treatment to obtain a supernatant and a precipitate containing ferrous sulfate crystals.

[0043] In some embodiments, the system of this application further includes a solid-liquid separation device for performing solid-liquid separation treatment on the sediment to obtain ferrous sulfate crystals.

[0044] As an example, combined Figure 1 The solid-liquid separation device includes a pressure filtration device 4, which is connected to the liquid-solid settling tank 3 via a first bottom drain pipe 41. One end of the first bottom drain pipe 41 is connected to the bottom of the liquid-solid settling tank 3, and the other end is connected to the pressure filtration device 4. In the embodiments of this application, the pressure filtration device 4 does not require a drive device and can operate using the large pressure difference between the external environment and the system, thus reducing energy consumption. A first pressure reducing valve 42 is also provided on the first bottom drain pipe 41. Opening or closing the first pressure reducing valve 42 controls whether the settled liquid in the liquid-solid settling tank 3 flows into the pressure filtration device 4.

[0045] In some embodiments, the system of this application further includes a heat exchange device for recovering waste heat from the supernatant.

[0046] As an example, combined Figure 1 The heat exchange device includes a flash evaporator 5, which is connected to the liquid-solid settling tank 3 via a first upper drain pipe 51. One end of the first upper drain pipe 51 is connected to the top of the liquid-solid settling tank 3, and the other end is connected to the flash evaporator 5. A flash valve 52 is also provided on the first upper drain pipe 51. By opening or closing the flash valve 52, the flow of the supernatant in the liquid-solid settling tank 3 into the flash evaporator 5 can be controlled.

[0047] In some embodiments, the first and second liquid phase treatment devices have identical structures. After a period of use, ferrous sulfate crystals gradually adhere to the inner wall of the system, forming scale, which reduces the system's low heat exchange efficiency and reaction rate. The first and second liquid phase treatment devices of this application are interchangeable. Thus, the zinc-iron solution enters the system from the second liquid phase treatment device; that is, the lower-temperature zinc-iron solution enters the second liquid phase treatment device, causing the ferrous sulfate crystals deposited on the inner wall of the second liquid phase treatment device to redissolve in the low-temperature zinc-iron solution.

[0048] As an example, refer to Figure 1 A second inlet pipe 31 is provided on the wall of the liquid-solid settling vessel 3. The second inlet pipe 31 is used to introduce zinc-iron solution into the liquid-solid settling vessel 3.

[0049] In some embodiments, a heating device is provided on the inner wall of the housing corresponding to the second liquid phase treatment device. As an example, a steam heating pipe is provided on the inner wall of the liquid-solid settling vessel 3. The steam heating pipe is used to heat the zinc-iron solution.

[0050] As an example, refer to Figure 1 The liquid-solid settling tank 3 is used to introduce zinc-iron solution, and correspondingly, the inlet buffer tank 1 is used to settle the ferrous sulfate suspension. The pressure filter device 4 is connected to the inlet buffer tank 1 via a second bottom drain pipe 43. One end of the second bottom drain pipe 43 is connected to the bottom of the inlet buffer tank 1, and the other end is connected to the pressure filter device 4. A second pressure reducing valve 44 is also installed on the second bottom drain pipe 43. Opening or closing the second pressure reducing valve 44 controls whether the settled liquid in the inlet buffer tank 1 flows into the pressure filter device 4.

[0051] Combination Figure 1 The flash evaporator 5 and the inlet buffer tank 1 are connected by a second upper drain pipe 53. One end of the second upper drain pipe 53 is connected to the top of the inlet buffer tank 1, and the other end is connected to the flash evaporator 5. The flash valve 52 can also control whether the supernatant in the inlet buffer tank 1 flows into the flash evaporator 5.

[0052] As an example, combined Figure 1 To more conveniently control the flow of supernatant and / or sediment in the inlet buffer tank 1 and / or liquid-solid settling tank 3, a first shut-off valve 32 is installed on the first bottom drain pipe 41 near the bottom of the liquid-solid settling tank 3, and a second shut-off valve 33 is installed on the first top drain pipe 51 near the top of the liquid-solid settling tank 3; a third shut-off valve 12 is installed on the second bottom drain pipe 43 near the bottom of the inlet buffer tank 1, and a fourth shut-off valve 13 is installed on the second top drain pipe 53 near the top of the inlet buffer tank 1.

[0053] In summary, the system of this application utilizes the inlet buffer vessel 1 to reduce the temperature difference between the zinc-iron solution and the horizontal reactor 2, thereby reducing the vibration of the horizontal reactor 2 caused by large temperature fluctuations. A liquid-solid settling vessel 3 is installed at the outlet end of the horizontal reactor 2 to settle the ferrous sulfate suspension, and a pressure filter device 4 is used for liquid-solid separation to obtain pure ferrous sulfate crystals. The pressure filter device 4 does not require a drive device and can operate using the large pressure difference between the external environment and the system, which can reduce energy consumption. More importantly, by interchangeding the inlet and outlet ends of the horizontal reactor 2, the lower-temperature zinc-iron solution can be used to dissolve the scale deposited on the walls of the horizontal reactor 2 and the liquid-solid settling vessel 3, which can complete the automatic cleaning of scale inside the vessel, thereby solving the problems of poor system operation and reduced reaction rate caused by scaling.

[0054] As an example, combined Figure 1 In this embodiment, the horizontal reactor 2 is equipped with seven consecutive sub-chambers 24. The specific working process of this embodiment is as follows: the zinc-iron solution is added to the inlet buffer vessel 1 through the first inlet pipe 11 (i.e., Figure 1 (On side A of the system), at this time, the third shut-off valve 12, the fourth shut-off valve 13, the second pressure reducing valve 44, and the second inlet pipe 31 are closed. The zinc-iron solution in the inlet buffer tank 1 is dissolved and heated to 120°C, then introduced into the horizontal reactor 2; subsequently, the zinc-iron solution is heated to 170°C in the horizontal reactor 2 and maintained at this temperature, while the working pressure of the horizontal reactor 2 is 1.0 MPa; after ferrous sulfate crystals precipitate from the zinc-iron solution in the horizontal reactor 2, the ferrous sulfate suspension is introduced into the liquid-solid settling tank 3 for settling treatment. The supernatant after settling enters the flash evaporator 5 through the first upper drain pipe 51, and after waste heat recovery treatment in the flash evaporator 5, the supernatant is returned to the wet zinc smelting system for reuse. The settling liquid enters the pressure filter device 4 through the first bottom drain pipe 41 to obtain ferrous sulfate crystals. After the system in this embodiment has been running for a period of time, the inlet end of the horizontal reactor 2 is switched to the liquid-solid settling tank 3 (i.e., Figure 1 (on side B of the reactor), at this time, the first shut-off valve 32, the second shut-off valve 33, the first pressure reducing valve 42, and the first inlet pipe 11 are closed. Interchanging the inlet and outlet ends of the horizontal reactor 2 can reduce the scaling of ferrous sulfate crystals on the inner wall of the system. After continuing operation for a period of time, it was found that only a small amount of ferrous sulfate crystals adhered to the inner wall of the liquid-solid settling tank 3 in this embodiment.

[0055] In the description of this application, "first feature" and "second feature" may include one or more of the features.

[0056] In the description of this application, "multiple" means two or more.

[0057] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A system for separating zinc and iron in a hydrometallurgical zinc smelting process, characterized in that, The system includes: A first liquid phase treatment device is used to perform a first heating treatment on a zinc-iron solution to obtain a heated zinc-iron solution. A reaction apparatus is used to subject the heated zinc-iron solution to a second heating treatment to obtain a ferrous sulfate suspension; the temperature of the second heating treatment is higher than the temperature of the first heating treatment. The second liquid phase treatment device is used to perform sedimentation treatment on the ferrous sulfate suspension to obtain a sediment, wherein the sediment includes ferrous sulfate crystals.

2. The system according to claim 1, characterized in that, The reaction apparatus includes a horizontal reaction vessel with multiple overflow baffles arranged at intervals in the inner cavity of the horizontal reaction vessel. The multiple overflow baffles divide the inner cavity into multiple sub-chambers, and two adjacent sub-chambers are connected through gaps in the overflow baffles.

3. The system according to claim 2, characterized in that, The notch in the overflow baffle is symmetrically arranged with the center of the sub-chamber as the center.

4. The system according to claim 3, characterized in that, The spacing between the overflow baffles is equal; and / or, The overflow baffle is arranged perpendicular to the length direction of the horizontal reaction vessel.

5. The system according to any one of claims 2-4, characterized in that, A stirring device is installed in the sub-chamber.

6. The system according to claim 1, characterized in that, Each of the first liquid phase treatment device, the reaction device, and the second liquid phase treatment device has a heating device independently installed on the inner wall of its corresponding housing. The heating device includes a steam heating pipe.

7. The system according to claim 1, characterized in that, The system satisfies at least one of the following conditions: (i) The heating temperature of the first heat treatment is 120℃-130℃; (ii) The operating pressure of the reaction device is 0.5 MPa-1.0 MPa; (iii) The heating temperature of the second heat treatment is 160℃-175℃.

8. The system according to claim 1, characterized in that, It also includes a solid-liquid separation device, which is used to perform solid-liquid separation treatment on the sediment to obtain ferrous sulfate crystals.

9. The system according to claim 1, characterized in that, The sedimentation process further includes obtaining a supernatant, and the system further includes a heat exchange device for recovering the waste heat from the supernatant.

10. The system according to claim 1, characterized in that, The first liquid phase processing device and the second liquid phase processing device have the same structure.

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