Comprehensive utilization and purification method and purification system for waste salt of salt-sodium sulfate system

Abstract

The invention provides a comprehensive utilization and purification method and purification system for waste salt of a salt-sodium sulfate system, and relates to the technical field of chemical engineering. The method comprises the following steps: S1, cleaning solid waste salt with water, and performing centrifugal separation to obtain a cleaning solution and solid waste salt a; s2, mixing the solid waste salt a and water under the action of stirring to prepare a solution a, and then carrying out cooling crystallization and centrifugal separation on the solution a to obtain mirabilite and a cooling mother solution; s3, performing evaporative crystallization and centrifugal separation on the cooling mother liquor to obtain industrial salt and evaporation mother liquor, and condensing and recovering water vapor evaporated in the evaporation crystallization process of the cooling mother liquor to obtain condensed water; s4, mixing the evaporation mother liquor with the cleaning solution obtained in the step S1 to obtain a mixed solution, evaporating the mixed solution to dryness to obtain solid waste salt b, and condensing and recovering water vapor evaporated in the evaporation mother liquor evaporation process to obtain condensed water; and S5, repeating the steps, and using the condensate water obtained in the steps as a water source. The method has the effects of saving resources and protecting the environment.

Description

Technical Field

[0001] The present application relates to the field of chemical technology, and in particular to a comprehensive utilization and purification method and purification system for waste salt from a saltpeter system. Background Art

[0002] Industrial waste salt is the crystallized salt slag produced in the production process of the chemical industry. It has the characteristics of many types, complex ingredients, high content of toxic and harmful substances, wide sources, high treatment costs, great environmental hazards and great resource utilization potential.

[0003] Solid industrial waste salt produced by my country's coal chemical industry has sodium chloride and sodium sulfate as the main components, and other miscellaneous salts as the secondary components. When treating this solid industrial waste salt, the existing technology needs to consume a lot of water resources to wash away most of the sodium chloride and sodium sulfate in the industrial waste salt, and then send the remaining solid industrial waste salt to a qualified solid waste disposal center for treatment or landfill.

[0004] However, due to the fragile ecological environment in the areas where my country's coal resources are mainly concentrated, water resources are quite scarce, accounting for only about 20% of the country's total water reserves. Therefore, the treatment of high-salt wastewater from coal chemical industry and water recycling and reuse are extremely important.

[0005] In view of this, it is necessary to provide a comprehensive utilization and purification method and purification system for waste salt from a saltpeter system. Summary of the invention

[0006] In order to solve the problem of waste of water resources in the prior art when treating industrial waste salt generated by the coal chemical industry, the present application provides a comprehensive utilization and purification method and purification system for waste salt from a saltpeter system.

[0007] In a first aspect, the present application provides a method for comprehensive utilization and purification of waste salt from a salt-nitre system, comprising the following steps: S1, first wash the solid waste salt with water, and then centrifuge to obtain a washing liquid and solid waste salt a; S2, firstly mixing the solid waste salt a and water under stirring to prepare a solution a, then cooling the solution a for crystallization and centrifugation to obtain sodium sulfate and cooling mother liquor; S3, evaporating and crystallizing the cooling mother liquor and centrifugally separating the cooling mother liquor to obtain industrial salt and evaporation mother liquor, and condensing and recovering the water vapor evaporated during the evaporation and crystallization of the cooling mother liquor to obtain condensed water; S4, first mixing the evaporation mother liquor with the cleaning liquid obtained in step S1 to obtain a mixed liquor, then evaporating the mixed liquor to obtain solid waste salt b, and condensing and recovering the water vapor evaporated during the evaporation of the evaporation mother liquor to obtain condensed water; S5. Repeat steps S1 to S4, and use the condensed water obtained in steps S3 and S4 as the water source required for steps S1 and S2.

[0008] By adopting the above technical scheme, since the solid waste salt is a mixture of sodium chloride, sodium sulfate and other various miscellaneous salts, step S1 can wash away most of the miscellaneous salts in the solid waste salt to obtain solid waste salt a with sodium chloride and sodium sulfate as main components; and since the solubility of sodium sulfate in water gradually decreases with decreasing temperature, the solubility of sodium chloride in water does not change significantly with temperature changes, step S2 can separate most of the sodium sulfate in the solid waste salt a to obtain Glauber's salt, and the entire process of separating sodium sulfate from the solid waste salt a does not involve phase change of water, which consumes less energy than the conventional evaporation crystallization separation method; S3 Step S4 can separate most of the sodium chloride in the solid waste salt a to obtain an industrial salt product, and step S5 can remix the remaining solid waste salt a (with various miscellaneous salts as the main components) with other miscellaneous salts washed out from the solid waste salt in step S1 to obtain solid waste salt b, so that the total mass of the solid waste salt b is greatly reduced compared with the original solid waste salt, thereby saving the cost of entrusting the solid waste salt to an external qualified solid waste disposal center for treatment; step S5 can cooperate with step S3 and step S4 to realize the water recycling of the entire salt nitrate system waste salt comprehensive utilization and purification method, thereby saving resources and protecting the environment.

[0009] Specifically, step S2 further includes: firstly recrystallizing the Glauber's salt obtained in step S2 to obtain Glauber's salt, and condensing and recovering the water vapor evaporated during the recrystallization of the Glauber's salt to obtain condensed water.

[0010] By adopting the above technical solution, the crystal water in the mirabilite (sodium sulfate decahydrate) can be recovered by recrystallization and condensation recovery.

[0011] Furthermore, step S5 also includes: using the condensed water obtained in steps S2, S3 and S4 as a water source required for steps S1 and S2.

[0012] By adopting the above technical solution, the crystal water recovered from Glauber's salt (sodium sulfate decahydrate) can continue to be used, thereby further realizing the water recycling of the entire salt-salt system waste salt comprehensive utilization and purification method.

[0013] Specifically, step S5 further includes: adding part of the solid waste salt b obtained in step S4 to the solution a.

[0014] By adopting the above technical scheme, since the solid waste salt b obtained in step S4 contains a higher content of sodium chloride and a lower content of sodium sulfate (compared to the content of sodium chloride), the user can add part of the solid waste salt b as a seed crystal into the solution a to be cooled and crystallized, which can not only promote the precipitation of sodium sulfate in the solution a by utilizing the common ion effect, but also further purify the solid waste salt b, thereby saving the cost of entrusting the solid waste salt to a qualified solid waste disposal center outside for treatment.

[0015] The second aspect of the present application provides a salt-nitre system waste salt comprehensive utilization and purification system, which adopts the following technical scheme: comprising a salt washing tank, a dissolving tank, a cooling crystallizer, an evaporator, a centrifuge, a mother liquor dryer and a condenser, wherein the salt washing tank can wash the solid waste salt and obtain a solid-liquid mixture of the washing liquid and the solid waste salt a; The dissolving tank can prepare the solid waste salt a with water to obtain the solution a; The cooling crystallizer is capable of cooling and crystallizing the solution a to obtain a solid-liquid mixture of the mirabilite and the cooling mother solution; The evaporator can evaporate and crystallize the cooled mother liquor to obtain a solid-liquid mixture of the industrial salt and the evaporated mother liquor; The centrifuge is capable of centrifugally separating the solid-liquid mixture of the cleaning liquid and the solid waste salt a, the solid-liquid mixture of the mirabilite and the cooling mother liquor, and the solid-liquid mixture of the industrial salt and the evaporation mother liquor; The mother liquor dryer can evaporate the mixed liquid to obtain the solid waste salt b; The condenser can condense and recover the cooling mother liquor and the water vapor evaporated during the evaporation and crystallization of the mixed liquor to obtain condensed water.

[0016] By adopting the above technical scheme, it is possible to realize the water recycling of the comprehensive utilization and purification method of waste salt in the entire salt nitrate system, thereby saving resources and protecting the environment; it is also possible to save the cost of entrusting the solid waste salt to an external qualified solid waste disposal center for treatment.

[0017] Specifically, the cooling crystallizer includes a tank body, a stirring unit and a cooling unit, the tank body is provided with a cooling chamber for containing the solution a, a liquid inlet is provided on the top wall of the cooling chamber, and a liquid outlet is provided on the bottom wall of the cooling chamber; The stirring unit is capable of stirring the solution a in the cooling chamber; The cooling unit can cool the solution a in the cooling chamber.

[0018] By adopting the above technical solution, the user can promote the full dissolution of fixed waste salt a in water through the stirring unit to prepare solution a, and can also refrigerate solution a through the cooling unit to precipitate sodium sulfate.

[0019] Furthermore, the stirring unit includes a main shaft, a sub-shaft, a main driving member, a stirring member and a sub-driving member. The main shaft and the cooling chamber are coaxially arranged in the cooling chamber, the sub-shaft is rotationally connected to the main shaft, the main driving member is transmission-connected to the main shaft, and can drive the main shaft to rotate so as to drive the sub-shaft to rotate around the main shaft, the stirring member is arranged on the sub-shaft, and the sub-driving member is transmission-connected to the sub-shaft and can drive the sub-shaft to rotate.

[0020] By adopting the above technical solution, the user can start the main driving member and the sub-driving member to drive the stirring member to perform a planetary motion of self-rotation and revolution around the rotation axis of the main shaft, so that the stirring member can fully stir the solution a.

[0021] Furthermore, it also includes a cleaning unit, which includes a scraper and a connecting rope. A slide groove is provided on the inner wall of the cooling chamber along the length direction of the sub-axis. One end of the scraper is inserted into the slide groove and can slide along the slide groove. One end of the connecting rope is connected to the scraper, and the other end of the connecting rope passes through a through hole provided at the top of the cooling chamber and extends out of the cooling chamber. A waist-shaped hole is provided on the top of the tank body along the direction from close to away from the scraper, the main driving member is connected to the tank body and can slide along the length direction of the waist-shaped hole, the main shaft passes through the waist-shaped hole and is connected to the main driving member, the stirring member is an equidistant spiral, and a spiral groove is formed between the top spiral surface and the bottom spiral surface of the stirring member, when the main driving member drives the stirring member to approach the scraper along the waist-shaped hole, the end of the scraper away from the slide groove can be inserted into the spiral groove and abut against the groove wall of the spiral groove, and when the scraper abuts against the groove wall of the spiral groove, the sub-driving member can drive the stirring member to rotate by driving the sub-shaft to drive the scraper to slide up and down along the slide groove.

[0022] By adopting the above technical solution, after a cooling crystallization is completed, the user can first move the main driving member close to the scraper along the length direction of the waist-shaped hole, so that the scraper can be inserted into the spiral groove formed between the top spiral surface and the bottom spiral surface of the equidistant spiral stirring member, and then control the sub-driving member to drive the stirring member to rotate forward or reversely, so that the scraper moves back and forth along the slide groove and removes the crystals adhered to the top spiral surface and the bottom spiral surface of the stirring member.

[0023] Furthermore, an observation window for observing the cooling cavity is provided on the top of the tank body.

[0024] By adopting the above technical solution, the user can observe through the observation window whether the crystals adhering to the stirring member have been removed.

[0025] Furthermore, a hook is provided on the side wall of the tank body, and a hanging ring is provided on the end of the connecting rope away from the scraper, and the hanging ring can be hung on the hook.

[0026] By adopting the above technical solution, after cleaning the crystals on the stirring element, the user can pull the scraper out of the cooling chamber by pulling the connecting rope.

[0027] In summary, the present application includes at least one of the following beneficial technical effects: 1. The method comprises the following steps: S1, washing the solid waste salt with water, and then centrifuging to obtain a washing liquid and solid waste salt a; S2, mixing the solid waste salt a with water under stirring to prepare a solution a, and then cooling and crystallizing the solution a and centrifuging to obtain sodium sulfate and a cooling mother liquor; S3, evaporating and crystallizing the cooling mother liquor and centrifuging to obtain industrial salt and an evaporation mother liquor, and condensing and recovering the water vapor evaporated during the evaporation and crystallization of the cooling mother liquor to obtain condensed water; S4, mixing the evaporation mother liquor with the washing liquid obtained in step S1 to obtain a mixed liquid, and then evaporating the mixed liquid to obtain solid waste salt b, and condensing and recovering the water vapor evaporated during the evaporation of the evaporation mother liquor to obtain condensed water; S5, repeating steps S1 to S4, and using the condensed water obtained in steps S3 and S4 as the water source required for steps S1 and S2. Since the solid waste salt is a mixture of sodium chloride, sodium sulfate and other various miscellaneous salts, step S1 can wash away most of the miscellaneous salts in the solid waste salt to obtain a solid waste salt with sodium chloride and sodium sulfate as the main components. a; and since the solubility of sodium sulfate in water gradually decreases with decreasing temperature, while the solubility of sodium chloride in water does not change significantly with temperature, step S2 can separate most of the sodium sulfate in solid waste salt a to obtain Glauber's salt, and the entire process of separating sodium sulfate from solid waste salt a does not involve phase change of water, which consumes less energy than conventional evaporation and crystallization separation methods; step S3 can separate most of the sodium chloride in solid waste salt a to obtain industrial salt products, and step S4 can remix the remaining solid waste salt a (with various impurities as the main components) with other impurities washed out from the solid waste salt in step S1 to obtain solid waste salt b, so that the total mass of solid waste salt b is greatly reduced compared to the original solid waste salt, thereby saving the cost of entrusting the solid waste salt to an external qualified solid waste disposal center for treatment; step S5 can cooperate with step S3 and step S4 to realize the water recycling of the entire salt nitrate system waste salt comprehensive utilization and purification method, thereby saving resources and protecting the environment; 2. It also includes a cleaning unit, which includes a scraper and a connecting rope. A sliding groove is provided on the inner wall of the cooling chamber along the length direction of the sub-axis. One end of the scraper is inserted into the sliding groove and can slide along the sliding groove. One end of the connecting rope is connected to the scraper, and the other end of the connecting rope extends out of the cooling chamber through a through hole provided at the top of the cooling chamber. A waist-shaped hole is provided on the top of the tank body along the direction from close to away from the scraper. The main driving part is connected to the tank body and can slide along the length direction of the waist-shaped hole. The main shaft passes through the waist-shaped hole and is connected to the main driving part. The stirring part is an equidistant spiral, and a spiral groove is formed between the top spiral surface and the bottom spiral surface of the stirring part. When the main driving part drives the stirring part along the waist-shaped hole When approaching the scraper, the end of the scraper away from the slide groove can be inserted into the spiral groove and abut against the groove wall of the spiral groove. When the scraper abuts against the groove wall of the spiral groove, the sub-drive component can drive the stirring element to rotate via the drive sub-shaft to drive the scraper to slide up and down along the slide groove. After one cooling crystallization is completed, the user can first move the main drive component close to the scraper along the length direction of the waist-shaped hole, so that the scraper can be inserted into the spiral groove formed between the top spiral surface and the bottom spiral surface of the equidistant spiral stirring element, and then control the sub-drive component to drive the stirring element to rotate forward or reversely, so that the scraper moves back and forth along the slide groove and removes the crystals adhered to the top spiral surface and the bottom spiral surface of the stirring element. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of a comprehensive utilization and purification method of waste salt from a salt-nitre system of the present application; Figure 2 It is a stereoscopic diagram of a cooling crystallizer in a second embodiment of a salt-nitrate system waste salt comprehensive utilization and purification system of the present application; Figure 3 It is a top view of a cooling crystallizer in a second embodiment of a salt-nitre system waste salt comprehensive utilization and purification system of the present application; Figure 4 is along Figure 3 A schematic cross-sectional view taken along the AA direction; Figure 5 is along Figure 3 A schematic cross-sectional view taken along the BB direction, in which only a portion of the tank body is shown.

[0029] Figure numerals: 1. tank body; 11. liquid inlet; 12. liquid outlet; 13. slide; 14. observation window; 15. hook; 16. slide rail; 17. cover plate; 2. stirring unit; 21. main shaft; 22. sub-shaft; 23. main drive member; 231. slider; 232. locking bolt; 24. stirring member; 25. sub-drive member; 3. cooling unit; 31. outer jacket; 311. cold inlet; 312. cold outlet; 4. cleaning unit; 41. scraper; 411. cleaning sleeve; 42. connecting rope; 421. hanging ring. DETAILED DESCRIPTION

[0030] The following is combined with Figure 1-5 For further explanation: See also Figure 1 A method for comprehensive utilization and purification of waste salt from a salt-nitre system, comprising the following steps: S1. First, wash the solid waste salt with water, and then centrifuge to obtain a washing liquid and solid waste salt a. Since the solid waste salt is a mixture of sodium chloride, sodium sulfate and other various miscellaneous salts, step S1 can wash away most of the miscellaneous salts in the solid waste salt to obtain a solid waste salt a with sodium chloride and sodium sulfate as the main components.

[0031] S2, firstly mix the solid waste salt a and water in a mass ratio of 1:3, and prepare solution a under stirring, then cool and crystallize the solution a (the solution a can be cooled to 0°C by using a refrigerant), and centrifuge to obtain Glauber's salt and cooling mother liquor, then recrystallize the Glauber's salt obtained in step S2 to obtain Sodium Sulfate, and condense and recover the water vapor evaporated in the recrystallization process of the Glauber's salt to obtain condensed water; since the solubility of sodium sulfate in water gradually decreases with decreasing temperature, and the solubility of sodium chloride in water does not change significantly with temperature changes, step S2 can separate most of the sodium sulfate in the solid waste salt a to obtain Glauber's salt, and the entire process of separating sodium sulfate from the solid waste salt a does not involve phase change of water, which consumes less energy than conventional evaporation and crystallization separation methods.

[0032] S3, evaporating and crystallizing the cooling mother liquor and centrifugally separating it to obtain industrial salt and evaporation mother liquor, and condensing and recovering the water vapor evaporated during the evaporation and crystallization of the cooling mother liquor to obtain condensed water; so that most of the sodium chloride in the solid waste salt a can be separated through step S3 to obtain an industrial salt product.

[0033] S4, firstly mix the evaporation mother liquor with the cleaning liquid obtained in step S1 to obtain a mixed liquor, then evaporate the mixed liquor to obtain solid waste salt b, and condense and recover the water vapor evaporated in the evaporation process of the evaporation mother liquor to obtain condensed water; so that the remaining solid waste salt a (with various impurity salts as the main components) can be mixed with other impurity salts washed out from the solid waste salt in step S1 through step S4 to obtain solid waste salt b, so that the total mass of solid waste salt b is greatly reduced compared with the original solid waste salt, thereby saving the cost required for entrusting the solid waste salt to an external qualified solid waste disposal center for treatment.

[0034] S5, repeating steps S1 to S4, and using the condensed water obtained in steps S2, S3 and S4 as the water source required for steps S1 and S2, and adding part of the solid waste salt b obtained in step S4 to solution a; by cooperating with steps S2, S3 and S4 to recover the evaporated water vapor and the crystal water in the mirabilite (sodium sulfate decahydrate), step S5 can realize the water recycling of the whole salt nitrate system waste salt comprehensive utilization and purification method, thereby saving resources and protecting the environment; since the predecessor evaporation mother liquor of the solid waste salt a is a saturated solution of sodium chloride and an unsaturated solution of sodium sulfate under high temperature conditions, the solid waste salt b contains a higher content of sodium chloride and a lower content of sodium sulfate (compared to the content of sodium chloride), the user can add part of the solid waste salt b as a seed to the solution a to be cooled and crystallized, which can not only promote the precipitation of sodium sulfate in the solution a by utilizing the common ion effect, but also realize the further purification of the solid waste salt b, thereby saving the cost required for entrusting the solid waste salt to a qualified solid waste disposal center for treatment.

[0035] Based on the above-mentioned method for comprehensive utilization and purification of waste salt from a salt-nitre system, the second aspect of the present application further provides a system for comprehensive utilization and purification of waste salt from a salt-nitre system. The system utilizes the above-mentioned method for comprehensive utilization and purification of waste salt from a salt-nitre system. In a first embodiment, the system specifically includes: a salt washing tank, a dissolving tank, a cooling crystallizer, an evaporator, a centrifuge, a mother liquor dryer and a condenser. The salt washing tank can wash the solid waste salt and obtain a solid-liquid mixture of a washing liquid and solid waste salt a. The dissolving tank can prepare a solution a by mixing the solid waste salt a with water. Both the salt washing tank and the dissolving tank can be stirring tanks with stirring devices. The crystallizer can be an OSLO crystallizer, so that the OSLO crystallizer can be used to cool and crystallize solution A to obtain a solid-liquid mixture of Glauber's salt and cooling mother liquor; the evaporator can evaporate and crystallize the cooling mother liquor to obtain a solid-liquid mixture of industrial salt and evaporation mother liquor; the centrifuge can centrifuge the solid-liquid mixture of cleaning liquid and solid waste salt a, the solid-liquid mixture of Glauber's salt and cooling mother liquor, and the solid-liquid mixture of industrial salt and evaporation mother liquor; the mother liquor dryer can evaporate the mixed liquor to obtain solid waste salt B; the condenser can condense and recover the cooling mother liquor and the water vapor evaporated during the evaporation and crystallization of the mixed liquor to obtain condensed water.

[0036] Since the salt-nitrate system waste salt comprehensive utilization and purification system of the present application utilizes the above-mentioned salt-nitrate system waste salt comprehensive utilization and purification method, it can also have all the technical effects of the above-mentioned salt-nitrate system waste salt comprehensive utilization and purification method, especially it can realize the water recycling utilization of the entire salt-nitrate system waste salt comprehensive utilization and purification method, thereby saving resources and protecting the environment; it can also save the cost required for entrusting the solid waste salt to an external qualified solid waste disposal center for treatment.

[0037] See also Figure 2and Figure 3 In the second embodiment, the cooling crystallizer includes a tank body 1, a stirring unit 2, a cooling unit 3 and a cleaning unit 4. A cooling chamber for containing solution a is provided inside the tank body 1. The cooling chamber can be an inverted cone. A liquid inlet 11 is provided on the top wall of the cooling chamber, and a liquid outlet 12 is provided on the bottom wall of the cooling chamber; the cooling unit 3 includes a jacket 31, which is provided outside the tank body 1 and forms a refrigerant chamber for accommodating refrigerant between the jacket 31 and the outer wall of the tank body 1. A cold inlet 311 and a cold outlet 312 are provided on the side wall of the refrigerant chamber, so that a user can connect a refrigerant circulation device with the cold inlet 311 and the cold outlet 312 to form a circulating cold flow that continuously enters and exits the refrigerant chamber, thereby cooling the solution a in the cooling chamber, and the cooling temperature can be zero degrees.

[0038] See also Figure 2 and Figure 3 The stirring unit 2 includes a main driving member 23, a main shaft 21, two sub-shafts 22, two stirring members 24 and two sub-driving members 25. A chute 13 with a T-shaped cross section is provided on the inner wall of the cooling chamber along the length direction of the sub-shaft 22. The top of the chute 13 extends to the top of the tank body 1 and forms an opening. The top of the tank body 1 is also provided with a slide rail 16 with a T-shaped cross section and a waist-shaped hole in a direction from close to away from the opening. The opening of the chute 13 and the top of the waist-shaped hole are A cover plate 17 is provided, each cover plate 17 is screwed to the tank body 1 through bolts and can block the waist-shaped hole and the opening of the slide groove 13. The main driving member 23 is slidably connected to the slide rail 16 through a slider 231 adapted to the slide rail 16. A locking bolt 232 is also screwed on the slider 231. After the locking bolt 232 is tightened, it can abut against the slide rail 16 and limit the movement of the slider 231 along the slide rail 16; a waist-shaped hole is opened at the top of the tank body 1 along the length direction of the slide rail 16. The output shaft of the main driving member 23 passes through the waist-shaped hole and is connected to the main shaft 21. The main shaft 21 and the cooling chamber are coaxially arranged in the cooling chamber. The two sub-shafts 22 are connected to the main shaft 21 with the main shaft 21 as the center and rotate relative to each other. The main driving member 23 can be a motor, so that the main shaft 21 can be driven to rotate by the main driving member 23. Each sub-shaft 22 is provided with a stirring member 24, which is an equidistant spiral, and a spiral groove is formed between the top spiral surface and the bottom spiral surface of the stirring member 24. The sub-driving member 25 corresponds to the sub-shafts 22 one by one, and each sub-driving member 25 is connected to a corresponding sub-shaft 22 in a transmission manner. The sub-driving member 25 can also be a motor, so that the sub-shaft 22 can be driven to rotate, so that the user can drive the stirring member 24 to rotate around the rotating axis of the main shaft 21 by starting the main driving member 23 and the sub-driving member 25, so that the stirring member 24 can fully stir the solution a.

[0039] See also Figure 3 and Figure 4The cleaning unit 4 includes a scraper 41 and a connecting rope 42. One end of the scraper 41 is a T-shaped block adapted to the slide groove 13, and the end of the scraper 41 is inserted into the slide groove 13 and can slide along the slide groove 13. A cleaning sleeve 411 can be set on the other end of the scraper 41, and the cleaning sleeve 411 can be a sponge sleeve soaked with cleaning liquid; one end of the connecting rope 42 is connected to the top of the scraper 41, and the other end of the connecting rope 42 passes through the through hole opened at the top of the cooling chamber and extends to the outside of the cooling chamber and is provided with a hanging ring 421. A hook 15 is provided on the outer wall of the tank body 1, and the hanging ring 421 can be hung on the hook 15.

[0040] The cleaning process of the cooling crystallizer of the salt-nitre system waste salt comprehensive utilization and purification system described in the present application is as follows: After one cooling crystallization is completed, the user can first rotate the main shaft 21 to align the stirring member 24 on any one of the sub-shafts 22 with the scraper 41, and then move the main driving member 23 along the slide rail 16 close to the scraper 41, so that the scraper 41 can be inserted into the spiral groove formed between the top spiral surface and the bottom spiral surface of the equidistant spiral stirring member 24, and then control the sub-driving member 25 to drive the stirring member 24 to rotate forward or reverse, so that the scraper 41 reciprocates along the slide groove 13 and removes the crystals adhered to the top spiral surface and the bottom spiral surface of the stirring member 24; after the cleaning of the sub-shaft 22 is completed, the user can first move the main driving member 23 away from the scraper 41 along the slide rail 16, and then align the stirring member 24 on another sub-shaft 22 with the scraper 41 by rotating the main shaft 21, and then repeat the above operation for cleaning; after the cleaning is completed, the user can lift the scraper 41 out of the tank body 1 through the connecting rope 42, so that the cleaning sleeve 411 on the scraper 41 can be replaced, and the scraper 41 will not hinder the cooling crystallization of the liquid in the cooling chamber.

[0041] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for comprehensive utilization and purification of waste salt from a salt-nitre system, characterized in that: The following steps are involved: S1, first wash the solid waste salt with water, and then centrifuge to obtain a washing liquid and solid waste salt a; S2, firstly mixing the solid waste salt a and water under stirring to prepare a solution a, then cooling the solution a for crystallization and centrifugation to obtain sodium sulfate and cooling mother liquor; S3, evaporating and crystallizing the cooling mother liquor and centrifugally separating the cooling mother liquor to obtain industrial salt and evaporation mother liquor, and condensing and recovering the water vapor evaporated during the evaporation and crystallization of the cooling mother liquor to obtain condensed water; S4, first mixing the evaporation mother liquor with the cleaning liquid obtained in step S1 to obtain a mixed liquor, then evaporating the mixed liquor to obtain solid waste salt b, and condensing and recovering the water vapor evaporated during the evaporation of the evaporation mother liquor to obtain condensed water; S5. Repeat steps S1 to S4, and use the condensed water obtained in steps S3 and S4 as the water source required for steps S1 and S2.

2. The method for comprehensive utilization and purification of waste salt from a salt-nitre system according to claim 1, characterized in that: Step S2 also includes: firstly recrystallizing the Glauber's salt obtained in step S2 to obtain Glauber's salt, and condensing and recovering the water vapor evaporated during the recrystallization process of the Glauber's salt to obtain condensed water.

3. The method for comprehensive utilization and purification of waste salt from a salt-nitre system according to claim 2, characterized in that: Step S5 further includes: using the condensed water obtained in steps S2, S3 and S4 as a water source required for steps S1 and S2.

4. The method for comprehensive utilization and purification of waste salt from a salt-nitre system according to claim 1, characterized in that: Step S5 also includes: adding part of the solid waste salt b obtained in step S4 into the solution a.

5. A system for comprehensive utilization and purification of waste salt from a salt-nitrate system, which is realized by the method for comprehensive utilization and purification of waste salt from a salt-nitrate system according to claim 1, characterized in that: include: A salt washing tank, a dissolving tank, a cooling crystallizer, an evaporator, a centrifuge, a mother liquor dryer and a condenser, wherein the salt washing tank is capable of washing the solid waste salt and obtaining a solid-liquid mixture of the washing liquid and the solid waste salt a; The dissolving tank can prepare the solid waste salt a with water to obtain the solution a; The cooling crystallizer is capable of cooling and crystallizing the solution a to obtain a solid-liquid mixture of the mirabilite and the cooling mother solution; The evaporator can evaporate and crystallize the cooled mother liquor to obtain a solid-liquid mixture of the industrial salt and the evaporated mother liquor; The centrifuge is capable of centrifugally separating the solid-liquid mixture of the cleaning liquid and the solid waste salt a, the solid-liquid mixture of the mirabilite and the cooling mother liquor, and the solid-liquid mixture of the industrial salt and the evaporation mother liquor; The mother liquor dryer can evaporate the mixed liquid to obtain the solid waste salt b; The condenser can condense and recover the cooling mother liquor and the water vapor evaporated during the evaporation and crystallization of the mixed liquor to obtain condensed water.

6. A salt-nitre system waste salt comprehensive utilization and purification system according to claim 5, characterized in that: The cooling crystallizer comprises a tank body (1), a stirring unit (2) and a cooling unit (3); a cooling chamber for containing the solution a is provided inside the tank body (1); a liquid inlet (11) is provided on the top wall of the cooling chamber, and a liquid outlet (12) is provided on the bottom wall of the cooling chamber; The stirring unit (2) is capable of stirring the solution a in the cooling chamber; The cooling unit (3) is capable of cooling the solution a in the cooling chamber.

7. A salt-nitre system waste salt comprehensive utilization and purification system according to claim 6, characterized in that: The stirring unit (2) comprises a main shaft (21), a sub-shaft (22), a main driving member (23), a stirring member (24) and a sub-driving member (25); the main shaft (21) and the cooling chamber are coaxially arranged in the cooling chamber; the sub-shaft (22) is rotatably connected to the main shaft (21); the main driving member (23) is transmission-connected to the main shaft (21) and can drive the main shaft (21) to rotate so as to drive the sub-shaft (22) to rotate around the main shaft (21); the stirring member (24) is arranged on the sub-shaft (22); the sub-driving member (25) is transmission-connected to the sub-shaft (22) and can drive the sub-shaft (22) to rotate.

8. A salt-nitre system waste salt comprehensive utilization and purification system according to claim 7, characterized in that: It also includes a cleaning unit (4), the cleaning unit (4) including a scraper (41) and a connecting rope (42), a slide groove (13) is provided on the inner wall of the cooling chamber along the length direction of the branch shaft (22), one end of the scraper (41) is inserted into the slide groove (13) and can slide along the slide groove (13), one end of the connecting rope (42) is connected to the scraper (41), and the other end of the connecting rope (42) passes through a through hole provided at the top of the cooling chamber and extends out of the cooling chamber; A waist-shaped hole is provided on the top of the tank body (1) in a direction from close to far away from the scraper (41); the main driving member (23) is connected to the tank body (1) and can slide along the length direction of the waist-shaped hole; the main shaft (21) passes through the waist-shaped hole and is connected to the main driving member (23); the stirring member (24) is an equidistant spiral, and a spiral groove is formed between the top spiral surface and the bottom spiral surface of the stirring member (24); when the main driving member (23) drives the stirring member (24) to approach the scraper (41) along the waist-shaped hole, the end of the scraper (41) away from the slide groove (13) can be inserted into the spiral groove and abut against the groove wall of the spiral groove; when the scraper (41) abuts against the groove wall of the spiral groove, the sub-driving member (25) can drive the stirring member (24) to rotate by driving the sub-shaft (22) to drive the scraper (41) to slide up and down along the slide groove (13).

9. A salt-nitre system waste salt comprehensive utilization and purification system according to claim 8, characterized in that: The top of the tank body (1) is provided with an observation window (14) for observing the cooling chamber.

10. A salt-nitre system waste salt comprehensive utilization and purification system according to claim 8, characterized in that: A hook (15) is provided on the side wall of the tank body (1), and a hanging ring (421) is provided on the end of the connecting rope (42) away from the scraper (41), and the hanging ring (421) can be hung on the hook (15).

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