Atmospheric pressure aluminum phosphate production system
By designing an atmospheric pressure aluminum phosphate production system, using aluminum chloride and disodium hydrogen phosphate as raw materials to synthesize aluminum phosphate, the problem of handling sodium tetrachloroaluminate byproducts in glufosinate production was solved, achieving low-cost and high-efficiency aluminum phosphate production, and reducing environmental pollution and energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- FUHUA TONGDA CHEM CO LTD
- Filing Date
- 2025-05-29
- Publication Date
- 2026-05-19
AI Technical Summary
In existing technologies, the sodium tetrachloroaluminate byproduct generated during glufosinate production is difficult to treat, resulting in severe environmental pollution from aluminum chloride waste treatment methods or limited market access for polyaluminum chloride products. Furthermore, these methods are energy-intensive and lack economic value.
Design an atmospheric pressure aluminum phosphate production system that uses aluminum chloride and disodium hydrogen phosphate as raw materials. The system uses equipment such as a reaction vessel, filter, washing and drying machine to synthesize aluminum phosphate, reducing equipment and pipelines, controlling the raw material feed rate and temperature, integrating mother liquor recovery and waste gas treatment, and simplifying the process flow.
It has enabled low-cost and high-efficiency aluminum phosphate production, reduced environmental pollution, improved resource utilization, simplified process flow, and reduced energy consumption.
Smart Images
Figure CN224252804U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of aluminum phosphate synthesis equipment, specifically relating to an atmospheric pressure aluminum phosphate production system. Background Technology
[0002] During the synthesis of glufosinate, sodium tetrachloroaluminate is produced as a byproduct, with a yield of 1.40-1.45 tons per ton of glufosinate. In the development of subsequent processing technologies for sodium tetrachloroaluminate, crystalline aluminum chloride intermediates are obtained; approximately one ton of crystalline aluminum chloride is obtained by processing one ton of waste residue. Currently, there are two main methods for treating aluminum chloride waste residue: one is direct landfilling, which has a significant environmental impact and wastes materials; the other is developing new process products, such as polyaluminum chloride (PAC). However, the second method of preparing PAC involves complex post-processing, high energy consumption, and the downstream market for PAC itself is limited, with low demand and low price, lacking a competitive advantage.
[0003] Our company is considering using the aluminum chloride waste residue generated from the subsequent treatment process of sodium tetrachloroaluminate and the disodium hydrogen phosphate byproduct of glyphosate production to synthesize a more economically valuable aluminum phosphate product. This would also solve the problem of large amounts of byproducts generated during the production of glufosinate and glyphosate. Therefore, there is an urgent need to develop an aluminum phosphate production system suitable for this process to meet the production needs of aluminum phosphate. Utility Model Content
[0004] The present invention aims to propose an atmospheric pressure aluminum phosphate production system for use in the process of synthesizing aluminum phosphate using aluminum chloride and disodium hydrogen phosphate as raw materials. The system has a simple structure, involves relatively few equipment and pipelines, and has low equipment cost.
[0005] To achieve the above-mentioned objectives, the technical solution of this utility model is as follows:
[0006] An atmospheric pressure aluminum phosphate production system includes a reactor and a controller. The reactor is connected to an aluminum chloride feed pipeline, a disodium hydrogen phosphate feed pipeline, and an alkali feed pipeline. A valve I is installed on the alkali feed pipeline, and the controller is connected to valve I. The reactor is equipped with a jacket or has heat exchange tubes inside. The bottom of the reactor is equipped with a discharge port. The reactor is equipped with a stirring mechanism and a temperature sensor. The reactor is connected to a condenser and then to a storage tank via pipelines.
[0007] Furthermore, the jacket or heat exchange tube is provided with a medium inlet and a medium outlet. The medium inlet is connected to a medium supply pipe, and a valve II is provided on the medium supply pipe. The valve II is controlled and connected to a temperature sensor.
[0008] Furthermore, valves III and IV are respectively installed on the aluminum chloride feed line and the disodium hydrogen phosphate feed line, and the controller is connected to valves III and IV respectively.
[0009] Furthermore, the front end of the aluminum chloride feed pipeline connected to the reactor is connected to a transfer tank for dissolving aluminum chloride, and the transfer tank is equipped with a reagent inlet and a solvent supply pipeline.
[0010] Furthermore, the discharge port of the reactor is connected to the feed port of the three-in-one filter washing and drying machine through pipeline I. The three-in-one filter washing and drying machine is connected to a rinsing liquid supply pipe. The bottom of the three-in-one filter washing and drying machine is equipped with a mother liquor outlet; the middle and lower part is equipped with a solid phase discharge port; the outside is equipped with a jacket through which heat exchange medium flows; the three-in-one filter washing and drying machine is equipped with a stirring mechanism and a temperature sensor.
[0011] Furthermore, a removable filter screen is provided below the solid phase outlet of the three-in-one filter washing and drying machine, and a spray pipeline is installed on the upper part of the three-in-one filter washing and drying machine, with the inlet of the spray pipeline connected to the rinsing liquid supply pipe.
[0012] Furthermore, the top of the three-in-one filter washing and drying machine is connected to an exhaust gas treatment system via pipeline.
[0013] Furthermore, the three-in-one filter washing and drying machine is connected to a mother liquor recovery system via a mother liquor outlet.
[0014] Furthermore, a transfer pump is installed on pipeline I.
[0015] Furthermore, the discharge port of the reactor is connected to the separator via pipeline II, the separator is connected to the feed port of the washing tower via pipeline III, the solid phase outlet of the separator is connected to the dryer via pipeline IV, and the material outlet of the washing tower is connected to the feed port of the separator via pipeline V.
[0016] The beneficial effects of this utility model are:
[0017] I. This utility model proposes a novel atmospheric pressure aluminum phosphate production system, which can be used in the synthesis of aluminum phosphate from aluminum chloride and disodium hydrogen phosphate. The system employs an atmospheric pressure reactor, involves relatively few devices and pipelines, and has low equipment costs. The aluminum chloride feed pipeline, disodium hydrogen phosphate feed pipeline, and alkali feed pipeline of the reactor are used to introduce the raw materials aluminum chloride, disodium hydrogen phosphate, and alkali solution, respectively. The alkali feed pipeline is equipped with valve I, which is connected to a controller. The feed rate of the alkali solution can be controlled by adjusting the opening degree of valve I to ensure the production of the target aluminum phosphate product.
[0018] II. In this utility model, the reactor of the atmospheric pressure aluminum phosphate production system is equipped with a jacket or heat exchange tube for introducing a heat exchange medium at a suitable temperature to heat the material in the reactor, thereby meeting the process requirements for aluminum phosphate production. Furthermore, a temperature sensor feeds back the temperature (change) of the material inside the reactor to the system controller, and the opening of valve II is then controlled to regulate the flow rate of the heat exchange medium, thus achieving temperature control.
[0019] Thirdly, this utility model proposes a preferred solution, namely, valves III and IV are respectively installed on the aluminum chloride feed pipeline and the disodium hydrogen phosphate feed pipeline, and the controller is connected to valves III and IV respectively. The controller controls the feeding speed of the raw materials in the aluminum chloride feed pipeline and the disodium hydrogen phosphate feed pipeline to achieve the purpose of controlling the reaction process.
[0020] IV. In this utility model, the front end of the aluminum chloride feed pipeline connected to the reaction vessel is connected to a transfer tank for dissolving aluminum chloride. The transfer tank is equipped with a reagent inlet and a solvent supply pipeline. The transfer tank is used to prepare an aluminum chloride solution of appropriate concentration first.
[0021] V. This utility model proposes a novel three-in-one filter, wash, and dryer that can perform the three functions of filtering, washing, and drying materials, avoiding material loss caused by material transfer and transportation, and reducing the risk of cross-contamination by reducing material transfer steps. Compared with separate filter + washing tower + dryer equipment, this three-in-one filter, wash, and dryer occupies less space and reduces the use of raw material pipelines.
[0022] VI. In this utility model, the top of the three-in-one filter washing and drying machine is connected to the exhaust gas treatment system via pipeline, allowing for timely delivery of exhaust gas to the system for centralized treatment. The mother liquor outlet of the three-in-one filter washing and drying machine is connected to the mother liquor recovery system via pipeline, facilitating centralized treatment of the mother liquor, maximizing material recycling, and reducing external emissions.
[0023] VII. This utility model also proposes an atmospheric pressure aluminum phosphate production system, in which a separator is connected to the rear end of the reactor, the separator is connected to the feed inlet of the washing tower through pipeline III, the solid phase outlet of the separator is connected to the dryer through pipeline IV, and the material outlet of the washing tower is connected to the feed inlet of the separator through pipeline V. It is not necessary to design a separate "three-in-one filter washing dryer". Traditional equipment such as separators, washing towers and dryers in industrial production can be used. Moreover, the three devices can work relatively independently. By reasonably planning the feeding ratio and feeding time, continuous production can be achieved. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the atmospheric pressure aluminum phosphate production system in Example 1.
[0025] Figure 2 This is a schematic diagram of one embodiment of the atmospheric pressure aluminum phosphate production system in Example 2.
[0026] Figure 3 This is a schematic diagram of one embodiment of the atmospheric pressure aluminum phosphate production system in Example 3.
[0027] Figure 4 This is a schematic diagram of one embodiment of the atmospheric pressure aluminum phosphate production system in Example 4.
[0028] Figure 5 This is a schematic diagram of another implementation of an aluminum phosphate production system under normal pressure.
[0029] Figure 6 This is a schematic diagram of another implementation of an atmospheric pressure aluminum phosphate production system.
[0030] Figure 7 This is a schematic diagram of one embodiment of the atmospheric pressure aluminum phosphate production system in Example 9.
[0031] Figure 8 This is a structural diagram of a three-in-one filter, wash, and dryer.
[0032] The components include: 1. Reactor; 2. Controller; 3. Aluminum chloride feed line; 4. Disodium hydrogen phosphate feed line; 5. Alkali feed line; 6. Valve I; 7. Jacket; 8. Stirring mechanism; 9. Temperature sensor; 10. Pressure sensor; 11. Medium supply pipe; 12. Valve II; 13. Valve III; 14. Valve IV; 15. Transfer tank; 16. Reagent inlet; 17. Solvent supply line; 18. Line I; 19. Three-in-one filter washing and drying machine; 20. Rinse solution. 21. Supply pipe; 22. Waste gas treatment system; 23. Mother liquor recovery system; 24. Transfer pump; 25. Pipeline II; 26. Separator; 27. Pipeline III; 28. Scrubber; 29. Pipeline IV; 30. Dryer; 31. Pipeline V; 32. Filter screen; 33. Spray pipeline; 34. Condenser; 15. Storage tank; 16.1. Discharge port; 7.1. Medium inlet; 7.2. Medium outlet; 19.1. Mother liquor outlet; 19.2. Solid phase discharge port; 27.1. Scrubber inlet. Detailed Implementation
[0033] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.
[0034] Example 1
[0035] An atmospheric pressure aluminum phosphate production system, belonging to the technical field of aluminum phosphate synthesis equipment, referenced. Figure 1The reactor includes a reactor 1 and a controller 2. The reactor 1 is connected to an aluminum chloride feed line 3, a disodium hydrogen phosphate feed line 4, and an alkali feed line 5. The alkali feed line 5 is equipped with a valve I6. The controller 2 is connected to the valve I6. The reactor 1 is equipped with a jacket 7 or has a heat exchange tube inside. The bottom of the reactor 1 is equipped with a discharge port 1.1. The reactor 1 is equipped with a stirring mechanism 8 and a temperature sensor 9. The reactor 1 is connected to a condenser 33 through a pipeline and then to a storage tank 34.
[0036] The most basic implementation method of this embodiment, when used:
[0037] First, aluminum chloride obtained during the development of the subsequent treatment process for sodium tetrachloroaluminate, a byproduct of glufosinate production, is prepared into a solution, and the aluminum chloride solution is added to the reactor 1 from the aluminum chloride feed line 3.
[0038] Then, disodium hydrogen phosphate, a byproduct of glyphosate production, is taken and added to the aluminum chloride solution from the disodium hydrogen phosphate feed line 4 in a certain proportion.
[0039] Finally, by introducing a heat exchange medium of appropriate temperature into the jacket 7 outside the reactor, the mixture in the reactor 1 is heated to the preset temperature. Then, alkali solution is added dropwise to the reactor 1 from the alkali solution feed line 5 in a certain proportion. When adding alkali solution, the opening of valve I6 is controlled by controller 2 to control the dripping rate of alkali solution. The temperature sensor 9 on the reactor 1 monitors the temperature inside the reactor, so that the reaction solution reacts within a certain temperature range for a period of time to obtain the reaction solution. The steam generated in the reactor 1 enters the condenser 33 through the pipeline and is cooled into liquid and temporarily stored in the storage tank 34.
[0040] Example 2
[0041] This embodiment is a further optimization of embodiment 1, the difference being that, as referenced... Figure 2 The jacket 7 or heat exchange tube is provided with a medium inlet 7.1 and a medium outlet 7.2. The medium inlet 7.1 is connected to a medium supply pipe 11, and a valve II 12 is provided on the medium supply pipe 11. The valve II 12 is controlled and connected to the temperature sensor 9.
[0042] Example 3
[0043] The difference between this embodiment and embodiments 1-2 is that, in reference to... Figure 3 Aluminum chloride feed line 3 and disodium hydrogen phosphate feed line 4 are respectively equipped with valve III13 and valve IV14, and controller 2 is connected to valve III13 and valve IV14 respectively.
[0044] Example 4
[0045] The difference between this embodiment and embodiments 1-3 is that, in reference... Figure 4The front end of the aluminum chloride feed line 3 connected to the reactor 1 is connected to a transfer tank 15 for dissolving aluminum chloride. The transfer tank 15 is equipped with a reagent inlet 16 and a solvent supply line 17.
[0046] Example 5
[0047] The difference between this embodiment and embodiments 1-4 is that, in reference to Figure 5 The discharge port 1.1 of the reactor 1 is connected to the feed port of the three-in-one filter washing dryer 19 through pipeline I18. The three-in-one filter washing dryer 19 is connected to the rinsing liquid supply pipe 20. The bottom of the three-in-one filter washing dryer 19 is provided with a mother liquor outlet 19.1; the middle and lower part is provided with a solid phase discharge outlet 19.2; the outside is provided with a jacket 7 through which heat exchange medium flows; the three-in-one filter washing dryer 19 is provided with a stirring mechanism 8 and a temperature sensor 9.
[0048] Preferably, a transfer pump 23 is installed on pipeline I18.
[0049] Example 6
[0050] The difference between this embodiment and embodiments 1-5 is that, in reference... Figure 8 The three-in-one filter washing and drying machine 19 has a detachable filter screen 31 below the solid phase outlet 19.2. The three-in-one filter washing and drying machine 19 is equipped with a spray pipeline 32 at the top. The inlet of the spray pipeline 32 is connected to the rinsing liquid supply pipe 20.
[0051] Example 7
[0052] The difference between this embodiment and embodiments 1-6 is that, in reference to... Figure 5 The top of the three-in-one filter washing and drying machine 19 is connected to the exhaust gas treatment system 21 via a pipeline.
[0053] Example 8
[0054] The difference between this embodiment and embodiments 1-7 is that, in reference to Figure 6 The three-in-one filter washing and drying machine 19 is connected to the mother liquor recovery system 22 through the mother liquor outlet 19.1.
[0055] Example 9
[0056] The difference between this embodiment and embodiments 1-8 is that, in reference to... Figure 7 The discharge port 1.1 of the reactor 1 is connected to the separator 25 through pipeline II 24. The separator 25 is connected to the feed port of the washing tower 27 through pipeline III 26. The solid phase outlet of the separator 25 is connected to the dryer 29 through pipeline IV 28. The material outlet of the washing tower 27 is connected to the feed port of the separator 25 through pipeline V 30.
[0057] In use, the reaction liquid obtained from reactor 1 is transferred to separator 25 for solid-liquid separation. The resulting mother liquor is sent to mother liquor recovery system 22 for unified collection and centralized processing. The crude aluminum phosphate product is sent to washing tower 27 through pipeline III 26 for soaking and washing. The material after washing is sent to separator 25 through pipeline V 30 for further processing. Washing tower 27 is replenished with washing liquid through washing liquid inlet 27.1. The soaking and separation operation is repeated 2 to 4 times. Finally, the solid product is sent to dryer 29 through pipeline IV 28 for drying.
[0058] Example 10
[0059] To facilitate public understanding of this solution, this embodiment uses the example of using the system to synthesize aluminum phosphate products from aluminum chloride waste residue generated by the subsequent treatment process of sodium tetrachloroaluminate and disodium hydrogen phosphate, a byproduct of glyphosate production, to further illustrate this solution.
[0060] For details, please refer to Figure 6 The atmospheric pressure aluminum phosphate production system includes a reactor 1, a three-in-one filter washing and drying machine 19, and a controller 2. The reactor 1 is connected to an aluminum chloride feed line 3, a disodium hydrogen phosphate feed line 4, and an alkali feed line 5. The alkali feed line 5 is equipped with a valve I6. The controller 2 is connected to the valve I6. The bottom of the reactor 1 is equipped with a discharge port 1.1. The reactor 1 is connected to a condenser 33 via a pipeline and then to a storage tank 34.
[0061] The discharge port 1.1 of the reactor 1 is connected to the inlet of the three-in-one filter washing and drying machine 19 via pipeline I 18. The three-in-one filter washing and drying machine 19 is connected to a rinsing liquid supply pipe 20. The bottom of the three-in-one filter washing and drying machine 19 is equipped with a mother liquor outlet 19.1; the middle and lower part is equipped with a solid phase discharge outlet 19.2. A transfer pump 23 is installed on pipeline I 18.
[0062] Both the reactor 1 and the three-in-one filter washing and drying machine 19 are equipped with a stirring mechanism 8 and a temperature sensor 9. Both the reactor 1 and the three-in-one filter washing and drying machine 19 are equipped with jackets 7 through which heat exchange medium flows.
[0063] In this embodiment, the jacket 7 is provided with a medium inlet 7.1 and a medium outlet 7.2. The medium inlet 7.1 is connected to a medium supply pipe 11, and a valve II 12 is provided on the medium supply pipe 11. The valve II 12 is controlled and connected to the temperature sensor 9.
[0064] In this embodiment, valves III13 and IV14 are respectively installed on aluminum chloride feed line 3 and disodium hydrogen phosphate feed line 4, and controller 2 is connected to valves III13 and IV14 respectively.
[0065] In this embodiment, the front end of the aluminum chloride feed line 3 connected to the reactor 1 is connected to a transfer tank 15 for dissolving aluminum chloride. The transfer tank 15 is equipped with a reagent inlet 16 and a solvent supply line 17.
[0066] In this embodiment, a removable filter screen 31 is provided below the solid phase outlet 19.2 of the three-in-one filter washing and drying machine 19, and a spray pipeline 32 is installed on the upper part of the three-in-one filter washing and drying machine 19. The inlet of the spray pipeline 32 is connected to the rinsing liquid supply pipe 20.
[0067] In this embodiment, the top of the three-in-one filter washing and drying machine 19 is connected to the exhaust gas treatment system 21 via a pipeline, and the mother liquor outlet 19.1 of the three-in-one filter washing and drying machine 19 is connected to the mother liquor recovery system 22 via a pipeline.
[0068] When using it, the specific steps are as follows:
[0069] S1. Take aluminum chloride obtained during the development of the subsequent treatment process of sodium tetrachloroaluminate, a by-product of glufosinate production, and add it into the transfer tank 15 through reagent inlet 16. Add water through solvent supply line 17 to dissolve the aluminum chloride to the preset concentration. The resulting aluminum chloride solution is then added into the reactor 1 through aluminum chloride feed line 3.
[0070] S2. Take disodium hydrogen phosphate, a byproduct of glyphosate production, and add it from the disodium hydrogen phosphate feed line 4 to the aluminum chloride solution in step S1 in a certain proportion.
[0071] S3. By introducing a heat exchange medium of appropriate temperature into the jacket 7 outside the reactor, the mixture in the reactor 1 is heated to the preset temperature. The steam generated in the reactor 1 enters the condenser 33 through the pipeline and is cooled into liquid and temporarily stored in the storage tank 34.
[0072] S4. Add alkali solution to the reactor 1 dropwise from the alkali solution feed line 5 at a certain ratio. When adding alkali solution, control the opening of valve I6 through controller 2 to control the dripping speed of alkali solution. Temperature sensor 9 on reactor 1 monitors the temperature inside the reactor, so that the reaction solution reacts within a certain temperature range for a period of time to obtain the reaction solution.
[0073] S5. The reaction solution from step S4 is then fed into the three-in-one filter washing and drying machine 19. The reaction solution undergoes preliminary filtration in the three-in-one filter washing and drying machine 19, and the resulting mother liquor is sent to the mother liquor recovery system 22 for centralized processing. Then, washing liquid is added to the three-in-one filter washing and drying machine 19 through the washing liquid supply pipe 20 to soak and wash the retained crude aluminum phosphate product. The washing and filtration operations are repeated 2 to 4 times to obtain purified aluminum phosphate product. Then, a high-temperature medium is introduced into the jacket 7 of the three-in-one filter washing and drying machine 19 to dry the solid and obtain aluminum phosphate powder.
Claims
1. An atmospheric pressure aluminum phosphate production system, characterized in that: The reactor includes a reactor (1) and a controller (2). The reactor (1) is connected to an aluminum chloride feed line (3), a disodium hydrogen phosphate feed line (4), and an alkaline feed line (5). The alkaline feed line (5) is equipped with a valve I (6). The controller (2) is connected to the valve I (6). The reactor (1) is equipped with a jacket (7) or a heat exchange tube. The reactor (1) is equipped with a discharge port (1.1) at the bottom. The reactor (1) is equipped with a stirring mechanism (8) and a temperature sensor (9). The reactor (1) is connected to a condenser (33) via a pipeline and then to a storage tank (34).
2. The atmospheric pressure aluminum phosphate production system according to claim 1, characterized in that: The jacket (7) or heat exchange tube is provided with a medium inlet (7.1) and a medium outlet (7.2). The medium inlet (7.1) is connected to a medium supply pipe (11). The medium supply pipe (11) is provided with a valve II (12). The valve II (12) is controlled and connected to a temperature sensor (9).
3. The atmospheric pressure aluminum phosphate production system according to claim 1, characterized in that: Aluminum chloride feed line (3) and disodium hydrogen phosphate feed line (4) are respectively equipped with valve III (13) and valve IV (14), and controller (2) is connected to valve III (13) and valve IV (14) respectively.
4. The atmospheric pressure aluminum phosphate production system according to claim 1, characterized in that: The front end of the aluminum chloride feed line (3) connected to the reactor (1) is connected to a transfer tank (15) for dissolving aluminum chloride. The transfer tank (15) is equipped with a reagent inlet (16) and a solvent supply line (17).
5. The atmospheric pressure aluminum phosphate production system according to claim 1, characterized in that: The discharge port (1.1) of the reactor (1) is connected to the feed port of the three-in-one filter washing dryer (19) through pipeline I (18). The three-in-one filter washing dryer (19) is connected to the rinsing liquid supply pipe (20). The bottom of the three-in-one filter washing dryer (19) is provided with a mother liquor outlet (19.1); the middle and lower part is provided with a solid phase discharge outlet (19.2); the outside is provided with a jacket (7) through which heat exchange medium flows; the three-in-one filter washing dryer (19) is provided with a stirring mechanism (8) and a temperature sensor (9).
6. The atmospheric pressure aluminum phosphate production system according to claim 5, characterized in that: The three-in-one filter washing and drying machine (19) has a removable filter screen (31) below the solid phase outlet (19.2) and a spray line (32) installed on the upper part of the three-in-one filter washing and drying machine (19). The inlet of the spray line (32) is connected to the rinsing liquid supply pipe (20).
7. The atmospheric pressure aluminum phosphate production system according to claim 5, characterized in that: The top of the three-in-one filter washing and drying machine (19) is connected to the exhaust gas treatment system (21) via a pipeline.
8. The atmospheric pressure aluminum phosphate production system according to claim 5, characterized in that: The three-in-one filter washing and drying machine (19) is connected to the mother liquor recovery system (22) through the mother liquor outlet (19.1).
9. The atmospheric pressure aluminum phosphate production system according to claim 5, characterized in that: A transfer pump (23) is installed on pipeline I (18).
10. The atmospheric pressure aluminum phosphate production system according to claim 1, characterized in that: The discharge port (1.1) of the reactor (1) is connected to the separator (25) through pipeline II (24). The separator (25) is connected to the feed port of the washing tower (27) through pipeline III (26). The solid phase outlet of the separator (25) is connected to the dryer (29) through pipeline IV (28). The material outlet of the washing tower (27) is connected to the feed port of the separator (25) through pipeline V (30).