Device for recycling mixed waste salt of sodium chloride and sodium sulfate

Abstract

The application provides a device for recycling mixed waste salt of sodium chloride and sodium sulfate, which comprises a mixed waste salt organic matter removal system, a low-chloride salt treatment system and a high-chloride salt treatment system connected to the discharge end of the mixed waste salt organic matter removal system respectively; the low-chloride salt treatment system comprises a low-chloride salt impurity removal system, a low-chloride salt evaporation crystallization system connected to the low-chloride salt solution outlet of the low-chloride salt impurity removal system, and a sodium sulfate refining system connected to the sodium sulfate crystal outlet of the low-chloride salt evaporation crystallization system. The application divides the mixed waste salt into low-chloride salt with high sodium sulfate content and high-chloride salt with low sodium sulfate content. The sodium sulfate refining system in the low-chloride salt treatment system can utilize the dissolution-crystallization balance principle and the physical entrainment balance principle of the sodium sulfate-sodium chloride-water ternary system to obtain high-quality sodium sulfate products, thereby simplifying the process, reducing the cost, improving the recovery rate of sodium sulfate, and obtaining relatively high-purity sodium sulfate products.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and more specifically, to a device for the resource recovery of mixed waste salt of sodium chloride and sodium sulfate. Background Technology

[0002] Industrial mixed waste salts, mainly composed of sodium chloride and sodium sulfate, have complex compositions and mostly originate from waste generated from end-of-pipe water treatment in industries such as coal chemical, hydrometallurgy, chlor-alkali, pharmaceutical, and printing and dyeing. Due to their high content of organic matter, heavy metals, and other pollutants, they are managed as hazardous waste.

[0003] Currently, the main technologies for the resource utilization of waste salt include thermal treatment, salt washing, alkali production, and oxidation. Salt washing is significantly affected by the composition of the waste salt and the content and type of organic matter; the use of organic solvents also poses a risk of secondary pollution. The quality of alkali-producing products is greatly influenced by the properties of the organic matter, making its application and promotion difficult.

[0004] Thermal treatment has attracted widespread attention due to its wide adaptability and good removal effect of organic matter. Literature reports that incinerating waste salt at 800℃ for 60 minutes essentially removes organic matter from chemical waste salt, and the salt melts and is produced as molten salt, with an organic matter content of 0.01wt%–0.02wt%, equivalent to (100–200) mg / kg. Jiang Haichao et al. used a fluidized bed to treat cyanide-containing sodium chloride waste salt at 700℃, and the total organic carbon (TOC), inorganic ammonium, and total ammonium of the treated product met the requirements for caustic soda feedstock. Yang Wenzhen et al. studied the treatment of typical pharmaceutical waste salt through a two-step process of low-temperature carbonization-high-temperature activation, recovering inorganic salts and activated carbon materials, achieving efficient removal of dissolved organic carbon (DOC) from the waste salt. However, the residual TOC content was still as high as 0.87 mg / g, and the recovered Na2SO4 product only met the Class III standard requirements of GB / T 6009-2014 "Industrial Anhydrous Sodium Sulfate".

[0005] When using thermal treatment to process waste salt containing organic matter, if the treatment temperature is too high, the waste salt will melt, which can easily lead to problems such as ring formation, agglomeration, and equipment corrosion during application. If the treatment temperature is too low, the organic matter may not be completely removed, leaving more residue and resulting in poor quality recovered salt products.

[0006] In addition, if organic matter is treated at high temperature and then purified to obtain a relatively clean mixed waste salt solution, and finally refined salt is obtained by evaporation and crystallization, sodium sulfate, sodium chloride, or mixed waste salt products of sodium sulfate and sodium chloride can be recovered, the quality of the products obtained by different purification levels and different treatment processes will be different.

[0007] Currently, the refining methods for mixed waste salts, mainly composed of sodium chloride and sodium sulfate, have the following main problems:

[0008] (1) The process cost is relatively high, and high-cost technologies such as sodium filter membranes are often used;

[0009] (2) It can obtain sodium sulfate, sodium chloride and mixed waste salts used in printing and dyeing auxiliaries, but the purity of the products is not high.

[0010] In view of this, the present invention is proposed. Summary of the Invention

[0011] The present invention aims to provide, for example, an apparatus for the resource recovery of mixed waste salts of sodium chloride and sodium sulfate, which simplifies the process of resource recovery of mixed waste salts of sodium chloride and sodium sulfate and eliminates the need for high-cost technical means such as sodium filter membranes.

[0012] The embodiments of the present invention can be implemented as follows:

[0013] In a first aspect, the present invention provides a device for the resource utilization of mixed waste salt of sodium chloride and sodium sulfate, including a mixed waste salt organic matter removal system, wherein the discharge end of the mixed waste salt organic matter removal system is respectively connected to a low chloride salt treatment system and a high chloride salt treatment system.

[0014] The low-chlorine salt treatment system includes a low-chlorine salt impurity removal system. The low-chlorine salt solution outlet of the low-chlorine salt impurity removal system is connected to a low-chlorine salt evaporation and crystallization system. The sodium sulfate crystal outlet of the low-chlorine salt evaporation and crystallization system is connected to a sodium sulfate refining system. The sodium sulfate refining system is also connected to the low-chlorine salt solution outlet of the low-chlorine salt impurity removal system.

[0015] The high-chloride salt treatment system includes a high-chloride salt dissolving tank, a high-chloride salt impurity removal system, and a high-chloride salt evaporation and crystallization system connected in sequence. The high-chloride salt dissolving tank is connected to the crystallization mother liquor outlet of the low-chloride salt evaporation and crystallization system.

[0016] In an optional embodiment, the mixed waste salt organic matter removal system includes a pretreatment system, a mixer, a carbonization furnace, and a discharge device connected in sequence. The discharge device is connected to the low-chlorine salt treatment system, and the mixer is connected to a carbonization accelerator feeding port.

[0017] In an optional embodiment, the pretreatment system includes a feeding belt, a feed hopper, and a drying furnace connected in sequence, wherein the drying furnace is connected to a mixer via a discharge belt.

[0018] In an optional embodiment, the low-chloride salt treatment system includes a low-chloride salt dissolving tank, a first filter press, a low-chloride salt multi-stage impurity removal tank, a second filter press, and a low-chloride salt buffer tank connected in sequence, wherein the buffer tank is connected to a low-chloride salt evaporation and crystallization system.

[0019] In an optional embodiment, the low-chlorine salt multi-stage impurity removal tank includes a tank for removing water-insoluble matter, a tank for removing heavy metals, a tank for removing fluoride, a dehardening tank, a decolorizing tank, and a pH adjustment tank.

[0020] In an optional embodiment, the sodium sulfate crystal outlet of the low-chlorine salt evaporation crystallization system is also connected to a drying and packaging system.

[0021] In an optional embodiment, the sodium sulfate refining system includes an upgrading and dissolving tank, which is equipped with a stirring assembly.

[0022] In an optional embodiment, a centrifuge is also connected in sequence to the sodium sulfate refining system. The solid phase outlet of the centrifuge is connected to a drying and packaging system, and the liquid phase outlet of the centrifuge is connected to the sodium sulfate refining system and a low-chlorine salt multi-stage impurity removal tank, respectively.

[0023] In an optional embodiment, the high-chloride salt impurity removal system includes a high-chloride salt multi-stage impurity removal tank, a third filter press, a filter, a decolorizing column, and a dyeing and printing auxiliary agent buffer tank connected in sequence. The dyeing and printing auxiliary agent buffer tank is connected to the feed inlet of the high-chloride salt evaporation and crystallization system.

[0024] In an optional embodiment, a drying and packaging system is connected to the high-chlorine salt evaporation and crystallization system.

[0025] The beneficial effects of the embodiments of the present invention include, for example:

[0026] Based on the composition of the mixed waste salt, the waste salt is divided into low-chloride salt with high sodium sulfate content and high-chloride salt with low sodium sulfate content. The low-chloride salt and high-chloride salt are processed by separate low-chloride and high-chloride salt treatment systems. The sodium sulfate refining system within the low-chloride salt treatment system utilizes the dissolution-crystallization equilibrium principle and physical entrainment equilibrium principle of the sodium sulfate-sodium chloride-water ternary system to obtain high-quality sodium sulfate products. The high-chloride salt treatment system yields dyeing and printing auxiliaries. The equipment provided by this invention simplifies the process, reduces costs, improves the recovery rate of sodium sulfate, and simultaneously produces relatively high-purity sodium sulfate products. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the connection of the equipment for the resource utilization of mixed waste salts of sodium chloride and sodium sulfate in this application.

[0029] Icons: 1-Feeding belt; 2-Feeding hopper; 3-Drying oven; 4-Discharge belt; 5-Mixer; 6-Carbonization furnace; 7-Discharge device; 8-Low chloride salt dissolving tank; 9-First filter press; 10-Low chloride salt multi-stage impurity removal tank; 11-Second filter press; 12-Low chloride salt buffer tank; 13-Low chloride salt evaporation and crystallization system; 14-Sodium sulfate refining system; 15-Centrifuge; 16-High chloride salt dissolving tank; 17-High chloride salt multi-stage impurity removal tank; 18-Third filter press; 19-Filter; 20-Decolorization column; 21-Dyeing and printing auxiliary agent buffer tank; 22-High chloride salt evaporation and crystallization system; 23-Drying and packaging system. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0033] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0034] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0035] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0036] Please refer to Figure 1This embodiment provides a device for the resource utilization of mixed waste salt of sodium chloride and sodium sulfate, including a mixed waste salt organic matter removal system, wherein the discharge end of the mixed waste salt organic matter removal system is respectively connected to a low chloride salt treatment system and a high chloride salt treatment system;

[0037] The low-chlorine salt treatment system includes a low-chlorine salt impurity removal system. The low-chlorine salt solution outlet of the low-chlorine salt impurity removal system is connected to a low-chlorine salt evaporation and crystallization system 13. The sodium sulfate crystal outlet of the low-chlorine salt evaporation and crystallization system 13 is connected to a sodium sulfate purification system 14. The sodium sulfate purification system 14 is also connected to the low-chlorine salt solution outlet of the low-chlorine salt impurity removal system.

[0038] The high-chloride salt treatment system includes a high-chloride salt dissolving tank 16, a high-chloride salt impurity removal system, and a high-chloride salt evaporation and crystallization system 22 connected in sequence. The high-chloride salt dissolving tank 16 is connected to the crystallization mother liquor outlet of the low-chloride salt evaporation and crystallization system 13.

[0039] This device treats inorganic mixed waste salts with sodium chloride and sodium sulfate as the main components. The economic value of sodium sulfate in the mixed waste salts is higher than that of sodium chloride. In order to further increase the added value of the product and thus improve economic benefits, the inorganic mixed waste salts are divided into high-chloride salts and low-chloride salts according to the proportion of sodium sulfate in them. Generally, the mass fraction of sodium sulfate in low-chloride salts is ≥50wt%, and the mass fraction of sodium sulfate in high-chloride salts is <50wt%. The specific distinction criteria can also be adjusted by those skilled in the art according to the actual situation and needs.

[0040] In other words, the equipment for resource utilization of mixed waste salts of sodium chloride and sodium sulfate provided in this embodiment of the invention processes the materials to be treated with different sodium sulfate contents separately. The low-chloride salt removal system obtains sodium sulfate products, while the high-chloride salt removal system obtains high-quality sodium chloride and sodium sulfate as dyeing and printing auxiliaries.

[0041] Based on the composition of the mixed waste salt, the mixed waste salt is divided into low-chloride salt with high sodium sulfate content and high-chloride salt with low sodium sulfate content. The low-chloride salt and high-chloride salt are processed by the low-chloride salt treatment system and the high-chloride salt treatment system, respectively. The sodium sulfate refining system 14 in the low-chloride salt treatment system can utilize the dissolution-crystallization equilibrium principle and physical entrainment equilibrium principle of the sodium sulfate-sodium chloride-water ternary system to obtain high-quality sodium sulfate products. The high-chloride salt treatment system can obtain dyeing and printing auxiliary products. The equipment provided by this invention can improve the recovery rate of sodium sulfate while simplifying the process and reducing costs, and at the same time prepare relatively high-purity sodium sulfate products (Class I Grade I or above).

[0042] In some embodiments, the mixed waste salt organic matter removal system includes a pretreatment system, a mixer 5, a carbonization furnace 6, and a discharge device 7 connected in sequence. The discharge device 7 is connected to the low-chlorine salt treatment system, and the mixer 5 is connected to a carbonization accelerator feeding port.

[0043] Organic matter in mixed waste salts can negatively impact subsequent treatment, especially since some mixed waste salts have high TOC content. Therefore, organic matter needs to be removed before treating mixed waste salts. In this application, carbonization is used. The mixed waste salts are mixed with a carbonization accelerator and then transferred to a carbonization furnace 6 for carbonization to remove organic matter (reducing TOC to 0.01 wt%) before being transferred to a low-chloride salt treatment system or a high-chloride salt treatment system. In some embodiments, the pretreatment system includes a feeding belt 1, a feed hopper 2, and a drying furnace 3 connected in sequence. The drying furnace 3 is connected to a mixer 5 via a discharge belt 4. Before carbonization, the mixed waste salts are dried to remove most of the moisture.

[0044] In some embodiments, the low-chloride salt treatment system includes a low-chloride salt dissolving tank 8, a first filter press 9, a low-chloride salt multi-stage impurity removal tank 10, a second filter press 11, and a low-chloride salt buffer tank 12 connected in sequence, wherein the buffer tank is connected to a low-chloride salt evaporation and crystallization system 13.

[0045] In specific operation, the first mixed waste salt is mixed and dissolved with water in the low-chlorine salt dissolving tank 8. The solid content can be controlled to be above 20wt%, that is, the solid content is controlled to 20wt% to saturation. Then, after separating the insoluble residue, multi-stage impurity removal is carried out. The impurity-removed low-chlorine salt solution is temporarily stored in the low-chlorine salt buffer tank 12.

[0046] In some embodiments, the low-chlorine salt multi-stage impurity removal tank 10 includes a water-insoluble matter removal tank, a heavy metal removal tank, a fluoride removal tank, a hardening removal tank, a decolorization tank, and a pH adjustment tank.

[0047] Specifically, in the low-chloride salt multi-stage impurity removal tank 10, the low-chloride salt solution is subjected to the following processes: removal of water-insoluble matter, removal of heavy metals, removal of fluoride, dehardening, decolorization, and pH adjustment. The goal is to ensure that the solution leaving the low-chloride salt multi-stage impurity removal tank 10 after these steps meets the following requirements: solute content ≥20wt%, water-insoluble matter <0.005wt%, and Ca... 2+ and Mg 2+ The total content of CaCO3 is ≤100ppm, Cd is ≤2ppm, heavy metals such as Fe, Cu, Ni, Zn, Cr, Mn and Pb are all ≤5ppm, fluorine content is ≤10ppm, solution color value is ≤100 degrees, and solution pH is 6-9.

[0048] In some embodiments, the removal of water-insoluble matter may be achieved through filtration, including but not limited to final precision filtration, to ensure that the content of water-insoluble matter in the salt solution meets the requirements. Heavy metal removal is selected from at least one of neutralization precipitation and sulfide precipitation, and may be one or a combination of both, to ensure that the heavy metal content meets the requirements. Fluoride removal is selected from at least one of calcium fluoride precipitation, aluminum-based adsorption precipitation, and resin adsorption fluoride removal, and may be one or a combination of these methods, to ensure that the fluoride content meets the requirements. De-hardening is selected from at least one of pH adjustment for magnesium precipitation and sodium carbonate precipitation for calcium precipitation, and may be one or a combination of both, to ensure that the calcium and magnesium content meets the requirements.

[0049] In some embodiments, decolorization is selected from at least one of oxidative decolorization and physical adsorption decolorization, and can be performed using a single method or a combination thereof, to ensure that the color value of the solution meets the requirements. Specifically, the oxidant in oxidative decolorization is selected from at least one of hydrogen peroxide and sodium hypochlorite, and the adsorbent in physical adsorption decolorization is selected from at least one of activated carbon and macroporous decolorizing resin. Decolorization ensures that the whiteness of the product meets the requirements.

[0050] In some embodiments, the sodium sulfate crystal outlet of the low-chlorine salt evaporation crystallization system 13 is also connected to a drying and packaging system 23.

[0051] The low-chlorine salt evaporation crystallization system 13 can control the chlorine content in the mother liquor to ≤145g / L, the water content of the wet sodium sulfate crystals to ≤5wt%, and the chlorine content on a dry basis to ≤1wt%. By controlling the chlorine content in the mother liquor and wet sodium sulfate crystals, the recovery rate and purity of the product are ensured. In actual operation, controlling the chlorine content in the mother liquor is used as the operating standard. The chloride ion concentration in the raw solution can be measured first, and the chlorine content can be theoretically calculated by controlling the concentration ratio of evaporation. At the same time, samples are taken to measure the chloride ion concentration.

[0052] The low-chlorine salt evaporation crystallization system 13 can be selected from single-effect evaporation, multi-effect evaporation, and MVR evaporation, and can operate in any mode; no limitation is made here. Currently, multi-effect and MVR evaporation are the main methods. Multi-effect evaporation has a decompression effect, which can lower the boiling point of the salt solution. However, in general, evaporation can only be achieved if the boiling point of the salt solution is above the corresponding pressure. The evaporation time is determined by the design capacity of the evaporator and has no special requirements. Generally speaking, it is sufficient to control the crystallization temperature to ≥40℃. If the crystallization temperature is too low, sodium sulfate will crystallize out as sodium sulfate decahydrate, which will seriously affect the purity of the product.

[0053] In some embodiments, the sodium sulfate refining system 14 includes an upgrading and dissolving tank, which is equipped with a stirring assembly. The low-chlorine mixed waste salt solution, after impurity removal in the low-chlorine multi-stage impurity removal tank 10, is transferred to the upgrading and dissolving tank. The chloride ion concentration in the low-chlorine mixed waste salt solution is controlled to be ≤50g / L, and the solution is saturated or nearly saturated, with a solute content ≥20wt%. It should be noted that the inventors creatively utilize the dissolution-crystallization equilibrium principle and physical entrainment equilibrium principle of the sodium sulfate-sodium chloride-water ternary system. Through scientific chlorine control, the sodium sulfate crystals obtained from the low-chlorine evaporation and crystallization system 13 are upgraded and dissolved using a saturated or nearly saturated low-chlorine mixed waste salt solution. During this process, sodium chloride in the sodium sulfate crystals further dissolves into the low-chlorine mixed waste salt solution, while a small amount of sodium sulfate in the solution precipitates out, achieving the purpose of further purifying the primary wet sodium sulfate.

[0054] In practical operation, the volume of low-chlorine mixed waste salt solution corresponding to each ton of sodium sulfate crystals can be controlled to be 2m³. 3 -4m 3 For example, it can be 2m 3 2.5m 3 3m 3 3.5m 3 4m 3 The upgrading and dissolution temperature is 35℃-65℃, and the upgrading and dissolution time is 15min-60min, to further improve the purity of the sodium sulfate product. Specifically, the upgrading and dissolution temperature can be 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, etc., and the upgrading and dissolution time can be 15min, 20min, 30min, 40min, 50min, 60min, etc. Furthermore, mechanical stirring is performed during the upgrading and dissolution process to promote the upgrading and dissolution conversion.

[0055] In some embodiments, a centrifuge 15 is also connected in sequence to the sodium sulfate refining system 14. The solid phase outlet of the centrifuge 15 is connected to a drying and packaging system 23, and the liquid phase outlet of the centrifuge 15 is connected to the sodium sulfate refining system 14 and the low-chlorine salt multi-stage impurity removal tank 10, respectively.

[0056] After the sodium sulfate crystals are upgraded and dissolved in the sodium sulfate refining system 14, solid-liquid separation is performed. The solid is dried to obtain sodium sulfate product that meets the requirements of Class I Grade 1. The liquid can be transferred to the sodium sulfate refining system 14 or the low-chlorine salt evaporation and crystallization system 13 to improve the recovery rate of sodium sulfate.

[0057] In some embodiments, the high-chloride salt impurity removal system includes a high-chloride salt multi-stage impurity removal tank 17, a third filter press 18, a filter 19, a decolorizing column 20, and a dyeing and printing auxiliary agent buffer tank 21 connected in sequence. The dyeing and printing auxiliary agent buffer tank 21 is connected to the feed inlet of the high-chloride salt evaporation and crystallization system 22.

[0058] The specific setup of the high-chloride multi-stage impurity removal tank 17 can refer to that of the low-chloride multi-stage impurity removal tank 10. It can include operational steps for removing water-insoluble matter, heavy metals, fluoride, hardening, decolorization, and pH adjustment. The salt solution treated by the high-chloride impurity removal system can meet the following requirements: solute content ≥20wt%, water-insoluble matter <0.005wt%, and Ca... 2+ and Mg 2+ The total content of CaCO3 is ≤100ppm, Cd is ≤2ppm, heavy metals such as Fe, Cu, Ni, Zn, Cr, Mn and Pb are all ≤5ppm, fluorine content is ≤10ppm, solution color value is ≤100 degrees, and solution pH is 6-9.

[0059] In some embodiments, a drying and packaging system 23 is connected to the high-chloride salt evaporation and crystallization system 22.

[0060] The high-chloride salt evaporation crystallization system 22 can be selected from single-effect evaporation, multi-effect evaporation, and MVR evaporation, and can operate in any mode; no limitation is made here. Currently, multi-effect and MVR evaporation are generally preferred. Multi-effect evaporation has a decompression effect, which can lower the boiling point of the salt solution. However, generally speaking, evaporation can only be achieved when the boiling point of the salt solution is above the corresponding pressure. The evaporation time is determined by the design capacity of the evaporator and has no special requirements. The crystallization temperature is controlled at ≥40℃, such as 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 95℃, etc.

[0061] The method for treating mixed waste salt using the equipment of this application is as follows: the organic matter in the mixed waste salt is removed by carbonization, and the specific composition of the carbonized mixed waste salt is: sodium chloride mass fraction of about 10 wt% and sodium sulfate mass fraction of 90 wt%, which is a low-chloride salt. It is then treated by a low-chloride salt treatment system.

[0062] The processing procedure includes the following steps:

[0063] (1) Mix and dissolve low-chlorine salt with water, control the solid content to 20wt%, and purify and remove impurities to obtain a saturated or nearly saturated low-chlorine mixed waste salt solution.

[0064] (2) The low-chlorine mixed waste salt solution was placed in an MVR evaporator for evaporation and crystallization at a crystallization temperature of 50℃, and the chlorine concentration of the mother liquor was controlled to be ≤145g / L. After cooling crystallization and centrifugation, sodium sulfate crystals and mother liquor were obtained. The water content of the sodium sulfate crystals was ≤5wt%, and the chlorine content on a dry basis was ≤1wt%.

[0065] (3) Add sodium sulfate crystals to the upgrading and dissolving tank, add purified low-chlorine mixed waste salt solution, control the mixed waste salt solution to be close to saturation, and control the chloride ion concentration to be 21.8 g / L, control the low-chlorine mixed waste salt solution / sodium sulfate crystal ratio to be 3 (m3 / t), the upgrading and dissolving temperature to be 40℃, and the upgrading and dissolving time to be 30 min, using mechanical stirring to promote upgrading and dissolving conversion. After the time requirement is met, centrifuge and filter it, and dry the obtained solid to obtain the product sodium sulfate (meeting Class I Grade 1); the obtained liquid is transferred to a multi-stage impurity removal tank or a low-chlorine salt evaporation crystallization system 13.

[0066] The obtained sodium sulfate product meets the requirements of Class I Grade 1 in GB / T 6009-2014, with whiteness ≥85, TOC content ≤50mg / kg, and leaching toxicity meets the standard.

[0067] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A device for recycling mixed waste salt resources of sodium chloride and sodium sulfate, characterized in that, The mixed waste salt organic matter removal system is connected with a low-chloride salt treatment system and a high-chloride salt treatment system at an outlet end respectively. The low-chloride salt treatment system comprises a low-chloride salt impurity removal system, a low-chloride salt evaporation crystallization system connected with a sodium sulfate crystal outlet of the low-chloride salt evaporation crystallization system, and a sodium sulfate refining system connected with a low-chloride salt solution outlet of the low-chloride salt impurity removal system. The low-chloride salt treatment system comprises a low-chloride salt dissolution tank, a first filter press, a low-chloride salt multi-stage impurity removal tank, a second filter press and a low-chloride salt buffer pool connected in sequence.

2. The device for recycling mixed waste salt of sodium chloride and sodium sulfate according to claim 1, characterized in that, The sodium sulfate refining system comprises a quality-improving dissolution tank provided with a stirring assembly.

3. The device for recycling mixed waste salt of sodium chloride and sodium sulfate according to claim 2, characterized in that, The low-chloride mixed waste salt solution after impurity removal in the low-chloride salt multi-stage impurity removal tank is transferred to the quality-improving dissolution tank, the concentration of chloride ions in the low-chloride mixed waste salt solution is controlled to be less than or equal to 50 g / L, and the salt solution is saturated or nearly saturated and has a solute content of more than or equal to 20 wt%.

4. The device for recycling mixed waste salt of sodium chloride and sodium sulfate according to claim 1, characterized in that, The high-chloride salt treatment system comprises a high-chloride salt dissolution tank, a high-chloride salt impurity removal system and a high-chloride salt evaporation crystallization system connected in sequence.

5. The device for recycling mixed waste salt of sodium chloride and sodium sulfate according to claim 1, characterized in that, The mixed waste salt organic matter removal system comprises a pretreatment system, a mixer, a carbonization furnace and a discharge device connected in sequence.

6. The device for recycling mixed waste salt of sodium chloride and sodium sulfate according to claim 1, characterized in that, The pretreatment system comprises a feeding belt, a feeding hopper and a drying furnace connected in sequence.

7. The device for recycling mixed waste salt of sodium chloride and sodium sulfate according to claim 1, characterized in that, The low-chloride salt multi-stage impurity removal tank comprises a water-insoluble impurity removal tank, a heavy metal removal tank, a fluorine removal tank, a hardening removal tank, a decolorization tank and a pH value adjustment tank. 8.The device for recycling mixed waste salt of sodium chloride and sodium sulfate according to claim 1, characterized in that, The sodium sulfate crystal outlet of the low-chloride salt evaporation crystallization system is further connected with a drying and packaging system. The sodium sulfate refining system is further connected with a centrifuge in sequence. The centrifuge is connected with a drying and packaging system at a solid phase outlet and connected with the sodium sulfate refining system and the low-chloride salt multi-stage impurity removal tank at a liquid phase outlet respectively. The high-chloride salt impurity removal system comprises a high-chloride salt multi-stage impurity removal tank, a third filter press, a filter, a decolorization column and a printing and dyeing auxiliary buffer pool connected in sequence. The high-chloride salt evaporation crystallization system is connected with a drying and packaging system.

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