Sodium sulfate waste salt utilization and treatment system

Abstract

The utility model discloses a sodium sulfate waste salt utilization and treatment system which comprises a dissolving unit, a reaction unit and a recovery unit which are connected in sequence, the dissolving unit comprises a sodium sulfate dissolving device and a calcium hydroxide dissolving device which are respectively used for dissolving waste salt sodium sulfate and calcium hydroxide in a methanol solution; the reaction unit comprises a reaction device connected with the dissolving unit and a separation device used for enabling a sodium sulfate solution to react with a calcium hydroxide solution to generate a sodium hydroxide solution and a calcium sulfate precipitate, and further comprises a separation device connected with the reaction device and used for separating the calcium sulfate precipitate and a filtrate containing sodium hydroxide; the recovery unit comprises a filtrate circulating device, a distillation device and an evaporation device which are connected in sequence, and the evaporation device is used for evaporating and concentrating filtrate to obtain a sodium hydroxide product with target concentration. The sodium sulfate waste salt recycling device realizes effective recycling of sodium sulfate waste salt, has economic value and environmental protection significance, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This utility model relates to the field of solid waste salt treatment and resource utilization technology, and in particular to a sodium sulfate waste salt utilization and treatment system. Background Technology

[0002] Sodium sulfate is an abundant natural mineral resource, primarily derived from mirabilite and calcium mirabilite deposits in salt lakes. Global annual sodium sulfate production exceeds 20 million tons, and with the large amounts of sodium sulfate waste produced as a byproduct of many chemical production processes, the total amount of usable solid sodium sulfate continues to increase. However, the industrial applications of sodium sulfate are relatively limited, and the market's capacity to absorb it is also limited, leading to a year-on-year decline in sodium sulfate consumption. This results in a large accumulation and stockpiling of solid sodium sulfate, preventing the effective conversion of sodium sulfate resource advantages into economic advantages. Utility Model Content

[0003] The purpose of this invention is to provide a sodium sulfate waste salt utilization and treatment system to achieve the effective recycling and utilization of sodium sulfate, thereby transforming the resource advantage of sodium sulfate into an economic advantage.

[0004] To achieve the above objectives, this utility model provides a sodium sulfate waste salt utilization and treatment system, comprising a dissolution unit, a reaction unit, and a recovery unit connected in sequence.

[0005] The dissolution unit includes a sodium sulfate dissolution device and a calcium hydroxide dissolution device, which are used to dissolve waste sodium sulfate and calcium hydroxide in methanol solution, respectively.

[0006] The reaction unit includes a reaction device and a separation device; the reaction device is connected to the dissolving unit via a pipeline and is used to react sodium sulfate solution with calcium hydroxide solution to generate sodium hydroxide solution and calcium sulfate precipitate; the separation device is connected to the reaction device and is used to separate the calcium sulfate precipitate and the filtrate containing sodium hydroxide.

[0007] The recovery unit includes a filtrate circulation device, a distillation device, and an evaporation device connected in sequence. The filtrate circulation device is used to detect the sodium hydroxide concentration in the filtrate and reintroduce low-concentration filtrate into the reaction device for secondary reaction. The distillation device is used to distill the filtrate to recover the methanol solution and send it back to the dissolution unit. The evaporation device is used to evaporate and concentrate the filtrate to obtain sodium hydroxide product of the target concentration.

[0008] As a further improvement of the present invention, the filtrate circulation device includes a filtrate collection tank and a circulation pump, the circulation pump having a first outlet for returning the filtrate to the reaction device and a second outlet for conveying the filtrate to the distillation device.

[0009] As a further improvement of the present invention, the filtrate collection tank is equipped with a concentration detector to detect the concentration of sodium hydroxide in the filtrate. When the sodium hydroxide concentration is ≤1 mol / L, the filtrate is re-transported to the reaction device for secondary reaction through the first outlet of the circulation pump; when the sodium hydroxide concentration is >1 mol / L, the filtrate is transported to the distillation device through the second outlet of the circulation pump.

[0010] As a further improvement of the present invention, the reaction apparatus includes a reaction vessel, a stirrer extending into the reaction vessel, and a heat exchanger outside the reaction vessel; the heat exchanger is used to control the reaction temperature of the reaction vessel to be 40-50°C.

[0011] As a further improvement of the present invention, the reaction vessel is a stainless steel vessel body, with a feed port at the top for adding sodium sulfate solution and calcium hydroxide solution; and a discharge port at the bottom for discharging the calcium sulfate precipitate and sodium hydroxide-containing filtrate after the reaction.

[0012] As a further improvement of the present invention, the stirrer is an anchor stirrer and is equipped with a motor drive for speed adjustment.

[0013] As a further improvement of the present invention, the reaction apparatus also includes a temperature sensor and a pressure sensor connected to the reaction vessel.

[0014] As a further improvement of the present invention, the concentration of the methanol solution is set to 40%-50%.

[0015] As a further improvement of the present invention, the separation device is a centrifuge, used to separate the calcium sulfate precipitate and the filtrate containing sodium hydroxide after the reaction, including a solid phase outlet and a liquid phase outlet, wherein the liquid phase outlet is connected to the filtrate circulation device through a pipeline.

[0016] As a further improvement of the present invention, the recovery unit further includes a methanol collection device, the distillation device having a distillation outlet connected to the methanol collection device and a filtrate outlet connected to the evaporation device, and the methanol collection device conveying the methanol solution to a sodium sulfate dissolving device and a calcium hydroxide dissolving device through pipelines.

[0017] The beneficial effects of this invention are as follows: The sodium sulfate waste salt utilization and treatment system provided by this invention integrates the sodium sulfate waste salt resource utilization process into a closed-loop process chain through a three-stage treatment system consisting of a dissolution unit, a reaction unit, and a recovery unit, achieving efficient treatment and resource utilization of sodium sulfate waste salt. The dissolution unit uses methanol solution as a solvent to effectively dissolve sodium sulfate and calcium hydroxide. The reaction unit controls the reaction conditions to allow the sodium sulfate solution and calcium hydroxide solution to react and generate sodium hydroxide solution and calcium sulfate precipitate, achieving effective conversion of the waste salt. The recovery unit further treats the filtrate, realizing the recovery and utilization of the methanol solution and obtaining sodium hydroxide product of the target concentration, which has high economic value. Attached Figure Description

[0018] Figure 1 This is a structural diagram of the sodium sulfate waste salt utilization and treatment system used in this utility model;

[0019] Figure 2 for Figure 1 Enlarged structural diagram of the dissolution unit of the sodium sulfate waste salt utilization and treatment system;

[0020] Figure 3 for Figure 1 A magnified structural diagram of the reaction unit in a sodium sulfate waste salt utilization and treatment system;

[0021] Figure 4 yes Figure 1 Enlarged structural diagram of the recovery unit of the sodium sulfate waste salt utilization and treatment system. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Please refer to them. Figures 1 to 4 The image shows one embodiment of this utility model.

[0023] In this utility model, unless otherwise explicitly specified and limited, the terms "set", "connect", "connect", "fixed" and other such terms should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means two or more, and at least two.

[0025] This invention provides a sodium sulfate waste salt utilization and treatment system. Figures 1 to 4 An embodiment according to the present invention is shown.

[0026] like Figure 1 As shown, the sodium sulfate waste salt utilization and treatment system includes a dissolution unit 1, a reaction unit 2, and a recovery unit 3 connected in sequence.

[0027] The dissolution unit 1 includes a sodium sulfate dissolution device 11 and a calcium hydroxide dissolution device 12, which are used to dissolve waste salt sodium sulfate and calcium hydroxide in methanol solution, respectively.

[0028] The reaction unit 2 includes a reaction device 21 and a separation device 22; the reaction device 21 is connected to the dissolution unit 1 through a pipe and is used to react sodium sulfate solution with calcium hydroxide solution to generate sodium hydroxide solution and calcium sulfate precipitate; the separation device 22 is connected to the reaction device 21 and is used to separate the calcium sulfate precipitate and the filtrate containing sodium hydroxide.

[0029] The recovery unit 3 includes a filtrate circulation device 31, a distillation device 32, and an evaporation device 33 connected in sequence. The filtrate circulation device 31 is used to detect the sodium hydroxide concentration in the filtrate and reintroduce the low-concentration filtrate into the reaction device 21 for a secondary reaction. The distillation device 32 is used to distill the filtrate to recover the methanol solution and send it back to the dissolution unit 1. The evaporation device 33 is used to evaporate and concentrate the filtrate to obtain a sodium hydroxide product of the target concentration.

[0030] This invention integrates the sodium sulfate waste salt resource utilization process into a closed-loop process chain through a three-stage treatment system consisting of a dissolution unit 1, a reaction unit 2, and a recovery unit 3, thereby achieving efficient treatment and resource utilization of sodium sulfate waste salt.

[0031] The dissolution unit 1 uses methanol solution as a solvent, which can more effectively dissolve sodium sulfate and calcium hydroxide. The reaction unit 2 controls the reaction conditions so that the sodium sulfate solution reacts with the calcium hydroxide solution to generate sodium hydroxide solution and calcium sulfate precipitate, thus realizing the effective conversion of waste salt.

[0032] The recovery unit 3 further processes the filtrate. The filtrate circulation device 31 monitors the concentration of sodium hydroxide in the filtrate in real time. When the concentration of sodium hydroxide in the filtrate is detected to be lower than the preset value, the filtrate circulation device 31 will reintroduce the low-concentration filtrate into the reaction device 21 through the pipeline to carry out a secondary reaction with the new sodium sulfate solution and calcium hydroxide solution, thereby improving the yield of sodium hydroxide and the resource utilization rate.

[0033] The distillation apparatus 32 is used to distill the high-concentration sodium hydroxide filtrate. Since methanol has a low boiling point, distillation allows for methanol recovery, enabling the recycling of the methanol solution and effectively reducing solvent costs. The evaporation apparatus 33 further concentrates the distilled sodium hydroxide solution to obtain a high-purity sodium hydroxide product. Through this processing system, this invention transforms waste sodium sulfate into high-value sodium hydroxide, achieving effective utilization of waste sodium sulfate and improving resource utilization and economic benefits.

[0034] Specifically, such as Figure 2 As shown, in the dissolution unit 1, the sodium sulfate dissolution device 11 is provided with a sodium sulfate inlet 13 and a methanol inlet 14, and the calcium hydroxide dissolution device 12 is provided with a calcium hydroxide inlet 15 and a methanol inlet 16.

[0035] Furthermore, the concentration of the methanol solution is set to 40%-50%. In a solution containing 40%-50% methanol, the forward reaction between sodium sulfate and calcium hydroxide can achieve the maximum sodium hydroxide yield. At the same time, the methanol solution is also easy to separate from the sodium hydroxide solution in the subsequent recovery unit 3, so as to realize the recovery and reuse of the solvent.

[0036] By adding solid sodium sulfate and a methanol solution with a concentration between 40% and 50% together into the sodium sulfate dissolving device 11, the solid sodium sulfate can be dissolved immediately to form a saturated sodium sulfate solution with a solubility of 28-30 g / L.

[0037] By adding solid calcium hydroxide and a methanol solution with a concentration between 40% and 50% into the calcium hydroxide dissolving device 12, the solid calcium hydroxide can be dissolved immediately to form a sodium hydroxide solution with an equimolar amount to the sodium sulfate solution.

[0038] The sodium sulfate dissolving device 11 and the calcium hydroxide dissolving device 12 are also equipped with a first stirrer 17 and a second stirrer 18, respectively, to promote the rapid dissolution of the raw material solids.

[0039] like Figure 3 As shown, a transfer pump 19 is provided between the reaction device 21 of the reaction unit 2 and the sodium sulfate dissolving device 11 and the calcium hydroxide dissolving device 12. The transfer pump controls the delivery of the dissolved sodium sulfate solution and calcium hydroxide solution to the reaction device 21 respectively.

[0040] The reaction apparatus 21 includes a reaction vessel 23, a third stirrer 24 extending into the reaction vessel 23, and a heat exchanger 25 outside the reaction vessel 23. The top of the reaction vessel 23 is provided with a feed inlet 28 for adding sodium sulfate solution and calcium hydroxide solution. In the reaction vessel 23, the sodium sulfate solution and calcium hydroxide solution undergo a forward reaction to generate sodium hydroxide solution and calcium sulfate precipitate. The bottom of the reaction vessel 23 is provided with a discharge outlet 29 for discharging the calcium sulfate precipitate and the filtrate containing sodium hydroxide after the reaction.

[0041] The reaction vessel 23 is made of a corrosion-resistant and high-temperature-resistant material. The material is selected from high-performance materials that are corrosion-resistant and high-temperature-resistant to adapt to corrosive substances and high-temperature environments that may be generated during the reaction process. In this embodiment, the reaction vessel 23 is preferably made of stainless steel.

[0042] To ensure the smooth progress of the reaction, the heat exchanger 25 is used to control the reaction temperature inside the reaction vessel 23, which is set between 40 and 50°C. The reaction time is controlled within 2 to 3 hours. Under these conditions, sodium sulfate and calcium hydroxide react in an equimolar ratio to produce sodium hydroxide and calcium sulfate. By optimizing the reaction conditions, the yield of sodium hydroxide can be increased.

[0043] The heat exchanger 25 is located outside the reactor body and can be supplied with a heating medium such as steam or hot water to control the reaction temperature.

[0044] The reaction apparatus 21 is also equipped with a third stirrer 24, which, through stirring, ensures that the two solutions are fully mixed and accelerates the reaction process.

[0045] The third agitator 24 is installed at the center of the top of the vessel and is an anchor-type agitator, which allows for more thorough mixing of materials within the vessel and improves reaction efficiency. The third agitator 24 can also be driven by a motor, with the stirring speed adjusted via a frequency converter.

[0046] In addition, the reaction apparatus 21 in this embodiment also includes a temperature sensor 26 and a pressure sensor 27 connected to the reaction vessel 23 to monitor the pressure and temperature during the reaction process in real time, so as to ensure the safety and stability of the entire reaction process.

[0047] The separation device 22 can use centrifugal separation or filtration to effectively separate the calcium sulfate precipitate from the filtrate containing sodium hydroxide. Optionally, the separation device 22 is a centrifuge, including a solid phase outlet 5 and a liquid phase outlet 6. The solid phase outlet 5 is connected to a calcium sulfate collection device, and the liquid phase outlet 6 is connected to the filtrate circulation device 31 through a pipeline.

[0048] When reaction unit 2 is operating, sodium sulfate solution and calcium hydroxide solution enter reaction vessel 23 through inlet 28 and are thoroughly mixed under the action of third stirrer 24. Heat exchanger 25 regulates the temperature to meet the reaction requirements, thereby promoting the smooth progress of the reaction. The heat required for the reaction is transferred to reaction vessel 23 through heat exchanger 25. As the reaction progresses, the generated calcium sulfate precipitate and sodium hydroxide solution are evenly distributed within reaction vessel 23. When the reaction reaches a predetermined time or a specific extent, the product will be discharged from outlet 29.

[0049] Reference Figure 3 and Figure 4 The filtrate circulation device 31 of the recovery unit 3 includes a filtrate collection tank 34 and a circulation pump 35. The circulation pump 35 has a first outlet 36 for returning the filtrate to the reaction device 21 and a second outlet 37 for conveying the filtrate to the distillation device 32.

[0050] The filtrate collection tank 34 is equipped with a concentration detector to detect the concentration of sodium hydroxide in the filtrate. When the sodium hydroxide concentration is ≤1 mol / L, the filtrate is re-transported to the reaction device 21 through the first outlet 36 of the circulation pump 35 for secondary reaction. When the sodium hydroxide concentration is >1 mol / L, the filtrate is transported to the distillation device 32 through the second outlet 37 of the circulation pump 35.

[0051] The filtrate circulation device 31 uses a circulation pump 35 to reintroduce the low-concentration filtrate into the reaction device 21 for a secondary reaction, thereby increasing the yield of sodium hydroxide.

[0052] The filtrate collection tank 34 is equipped with a fourth stirrer 38 to ensure that the filtrate is mixed evenly in the collection tank and to avoid uneven distribution of sodium hydroxide concentration, which would lead to a decrease in the circulation treatment effect.

[0053] The distillation apparatus 32 employs high-efficiency distillation technology to distill the filtrate to recover the methanol solution, achieving resource recycling. The recovery unit 3 also includes a methanol collection device 9, designed to receive the methanol solution distilled from the distillation apparatus 32. The distillation apparatus 32 has a distillation outlet 7 connected to the methanol collection device 9 and a filtrate outlet 8 connected to the evaporation apparatus 33. The filtrate outlet 8 of the distillation apparatus 32 is connected to the evaporation apparatus 33, transporting the remaining filtrate after distillation to the evaporation apparatus 33 for further processing.

[0054] A condenser may be provided between the methanol collection device 9 and the distillation device 32 to ensure that the methanol vapor discharged from the distillation outlet 7 can be effectively condensed into a liquid form for subsequent collection and storage.

[0055] The methanol collection device 9 uses pipelines and pumps to re-transport the recovered methanol solution to the sodium sulfate dissolving device 11 and the calcium hydroxide dissolving device 12 for the next round of sodium sulfate waste salt utilization. This effectively reduces methanol waste, maximizes resource utilization in the entire treatment system, lowers production costs, and plays a positive role in environmental protection.

[0056] The evaporation device 33 employs evaporation and concentration technology to evaporate and concentrate the filtrate to obtain sodium hydroxide product of the target concentration. Preferably, the sodium hydroxide concentration is controlled to be greater than 40% to meet the requirements of industrial-grade products and market demand.

[0057] The recovery unit 3 also includes a final product tank 10 connected to the evaporator to collect the concentrated sodium hydroxide after evaporation in the evaporator into the final product tank 10.

[0058] In summary, the sodium sulfate waste salt utilization and treatment system provided by this invention integrates the sodium sulfate waste salt resource utilization process into a closed-loop process chain through a three-stage treatment system consisting of a dissolution unit, a reaction unit, and a recovery unit, achieving efficient treatment and resource utilization of sodium sulfate waste salt. The dissolution unit uses methanol solution as a solvent to effectively dissolve sodium sulfate and calcium hydroxide. The reaction unit controls the reaction conditions to allow the sodium sulfate solution and calcium hydroxide solution to react and generate sodium hydroxide solution and calcium sulfate precipitate, achieving effective conversion of waste salt. The recovery unit further treats the filtrate, realizing the recovery and utilization of the methanol solution and obtaining sodium hydroxide product of the target concentration. This transforms low-value-added sodium sulfate waste salt into high-value-added sodium hydroxide product, improving resource utilization and possessing high economic value.

[0059] In the embodiments provided by this utility model, it should be understood that the above-described implementation of the structure is merely illustrative. For example, the division of the modules is merely a logical functional division. In actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0060] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A sodium sulfate waste salt utilization and treatment system, characterized in that, It includes a dissolution unit, a reaction unit, and a recovery unit connected in sequence; The dissolution unit includes a sodium sulfate dissolution device and a calcium hydroxide dissolution device, which are used to dissolve waste sodium sulfate and calcium hydroxide in methanol solution, respectively. The reaction unit includes a reaction device and a separation device; The reaction device is connected to the dissolving unit via a pipeline and is used to react sodium sulfate solution with calcium hydroxide solution to generate sodium hydroxide solution and calcium sulfate precipitate; the separation device is connected to the reaction device and is used to separate the calcium sulfate precipitate and the filtrate containing sodium hydroxide. The recovery unit includes a filtrate circulation device, a distillation device, and an evaporation device connected in sequence. The filtrate circulation device is used to detect the sodium hydroxide concentration in the filtrate and reintroduce low-concentration filtrate into the reaction device for secondary reaction. The distillation device is used to distill the filtrate to recover the methanol solution and send it back to the dissolution unit. The evaporation device is used to evaporate and concentrate the filtrate to obtain sodium hydroxide product of the target concentration.

2. The sodium sulfate waste salt utilization and treatment system according to claim 1, characterized in that, The filtrate circulation device includes a filtrate collection tank and a circulation pump, the circulation pump having a first outlet for returning the filtrate to the reaction apparatus and a second outlet for conveying the filtrate to the distillation apparatus.

3. The sodium sulfate waste salt utilization and treatment system according to claim 2, characterized in that, The filtrate collection tank is equipped with a concentration detector to detect the concentration of sodium hydroxide in the filtrate. When the sodium hydroxide concentration is ≤1 mol / L, the filtrate is returned to the reaction device for secondary reaction through the first outlet of the circulation pump; when the sodium hydroxide concentration is >1 mol / L, the filtrate is sent to the distillation device through the second outlet of the circulation pump.

4. The sodium sulfate waste salt utilization and treatment system according to any one of claims 1-3, characterized in that, The reaction apparatus includes a reaction vessel, a stirrer extending into the reaction vessel, and a heat exchanger outside the reaction vessel; the heat exchanger is used to control the reaction temperature of the reaction vessel to 40-50°C.

5. The sodium sulfate waste salt utilization and treatment system according to claim 4, characterized in that, The reaction vessel is made of corrosion-resistant and high-temperature-resistant material. It has a feed inlet at the top for adding sodium sulfate solution and calcium hydroxide solution, and a discharge outlet at the bottom for discharging the calcium sulfate precipitate and sodium hydroxide-containing filtrate after the reaction.

6. The sodium sulfate waste salt utilization and treatment system according to claim 4, characterized in that, The agitator is an anchor-type agitator and is equipped with a motor drive for speed adjustment.

7. The sodium sulfate waste salt utilization and treatment system according to claim 4, characterized in that, The reaction apparatus also includes a temperature sensor and a pressure sensor connected to the reaction vessel.

8. The sodium sulfate waste salt utilization and treatment system according to claim 1, characterized in that, The concentration of the methanol solution is set to 40%–50%.

9. The sodium sulfate waste salt utilization and treatment system according to claim 3, characterized in that, The separation device is a centrifuge used to separate the calcium sulfate precipitate and the sodium hydroxide-containing filtrate after the reaction. It includes a solid phase outlet and a liquid phase outlet, and the liquid phase outlet is connected to the filtrate circulation device through a pipeline.

10. The sodium sulfate waste salt utilization and treatment system according to claim 1, characterized in that, The recovery unit also includes a methanol collection device. The distillation device has a distillation outlet connected to the methanol collection device and a filtrate outlet connected to the evaporation device. The methanol collection device transports the methanol solution to a sodium sulfate dissolving device and a calcium hydroxide dissolving device through pipelines.

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