A production process and application for reducing t323 production waste liquid

Abstract

The application relates to the field of thiocarbamate production, and particularly discloses a production process for reducing T323 production waste liquid and application. The production process for reducing T323 production waste liquid comprises the following steps: (1) adding ethanol as a solvent, solid alkali, carbon disulfide and dichloromethane, and mixing at normal temperature; (2) controlling the temperature to be less than 15 DEG C, adding dibutylamine dropwise, and then increasing the temperature to 70-80 DEG C for reaction for 3 hours after the dropwise addition is completed; and (3) cooling to below 50 DEG C, adding an extraction solvent hexane, and separating layers to obtain a T323 product. The production process for reducing T323 production waste liquid has the advantages of reducing production waste liquid and being green and environment-friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thio-carbamate production, more particularly, it relates to a production process and application for reducing T323 production waste liquid. BACKGROUND

[0002] T323, the chemical name of which is thio-carbamate, is an ash-free multi-effect additive. Its structure does not contain metal atoms, and the sulfur content is as high as 30%. It not only has outstanding extreme pressure and anti-wear properties, but also shows good anti-oxidation effect. T323 is mainly applied to various oil products such as turbine oil, hydraulic oil, gear oil, and internal combustion engine oil, to improve the anti-oxidation and anti-wear properties of the oil products, and can also improve the TimKenOK load of lubricating grease and is widely used.

[0003] At present, in the production process of T323, the traditional process uses liquid alkali as one of the reactants. This method has long occupied a dominant position in the industry due to its mature process and simple operation. However, with the continuous expansion of production scale, the limitations of this traditional process have gradually emerged.

[0004] The T323 production process involving liquid alkali produces a large amount of waste liquid containing sodium chloride. The composition of these waste liquids is complex and difficult to treat. Currently, enterprises usually use evaporation crystallization, ion exchange and other methods to treat waste liquids, but these methods have problems such as high energy consumption, large equipment investment, and high treatment cost. More seriously, if the waste liquid is not properly treated, harmful substances in it may seep into the soil and water, causing irreversible damage to the ecological environment, which goes against the concept of sustainable development. Therefore, it is urgent to develop a more environmentally friendly T323 production process. SUMMARY

[0005] In order to develop a more environmentally friendly T323 production process and reduce production waste liquid, the present application provides a production process and application for reducing T323 production waste liquid.

[0006] The production process for reducing T323 production waste liquid provided by the present application adopts the following technical solution:

[0007] A production process for reducing T323 production waste liquid, comprising the following steps:

[0008] (1) adding ethanol as a solvent, solid alkali, carbon disulfide and dichloromethane, and mixing at room temperature;

[0009] (2) control the temperature <15℃, add dibutylamine dropwise, and after the dropwise addition is completed, heat to 70-80℃ and react for 3 hours;

[0010] (3) cool to below 50℃, add extraction solvent hexane, and separate to obtain T323 product.

[0011] By adopting the above technical scheme, the process replaces the traditional liquid alkali with solid alkali, thereby reducing the introduction of water in the production process from the source and avoiding the generation of high-water-content waste liquid caused by liquid alkali aqueous solution. Ethanol, as a solvent, forms a homogeneous reaction system with dichloromethane and carbon disulfide, thereby ensuring the uniform dispersion of solid alkali ultrafine particles, improving the reaction efficiency, and reducing the generation of by-products. When dibutylamine is added dropwise, the temperature is controlled to be less than 15°C, thereby inhibiting the exothermic side reaction and avoiding the generation of impurities caused by excessive hydrolysis, so as to reduce the pollutant content of waste liquid in the subsequent separation process. The temperature is increased to 70-80°C, and the reaction is kept constant for 3 hours, so that the raw materials are fully converted, the yield of the target product is improved, and the residual unreacted raw materials are reduced. Hexane is used as an extraction solvent, and the extremely low mutual solubility of hexane and water is used to realize the efficient separation of the T323 product. After the separation, the water phase only contains dissolved inorganic salts and a small amount of solvent, thereby significantly reducing the concentration of organic matter in the waste liquid and creating favorable conditions for subsequent salt water treatment.

[0012] Optionally, the method further comprises step (4): recovering the solvent in the organic phase by multi-stage rectification, wherein the organic phase comprises ethanol and hexane.

[0013] By adopting the above technical scheme, after the T323 product is obtained by separation, the organic phase (containing ethanol, hexane, and a small amount of residual solvent) is recovered by multi-stage rectification, so that the solvent can be recycled. In the traditional process, the solvent is often discharged with waste liquid or needs to be treated by high-energy consumption distillation. However, in this step, ethanol and hexane are recovered in a targeted manner, so that the consumption of new solvent is greatly reduced, and the production cost is reduced. At the same time, the solvent as a component of waste liquid is avoided to enter the subsequent treatment link, so that the organic pollutant emission is reduced from the source, and the clean production requirement is met. The multi-stage rectification process can accurately control the separation efficiency of different solvents, so that the purity of the recovered solvent meets the production reuse standard, a closed-loop system of “use-recovery-reuse” is formed, and the environmental protection performance of the process is further improved.

[0014] Optionally, the method for recovering the solvent in the organic phase comprises the following steps:

[0015] The organic phase after the separation of T323 production is introduced into a multi-stage rectification tower.

[0016] The operation pressure of the rectification tower is controlled to be 0-0.5 MPa, the temperature of the tower bottom is controlled to be 60-150°C, and the temperature of the tower top is controlled to be 40-80°C.

[0017] The gas phase flow in the middle of the tower is cooled to 40-60°C and then returned to the tower, so that the mixed solvent of ethanol and hexane is separated and recovered.

[0018] By adopting the technical scheme, the operation pressure of the rectifying tower is set to 0-0.5 MPa, the tower kettle temperature is 60-150 DEG C, and the tower top temperature is 40-80 DEG C, the boiling point difference between ethanol (boiling point 78.4 DEG C) and hexane (boiling point 68.7 DEG C) is used, and the two solvents are efficiently separated. The gas phase flow in the middle of the tower is cooled and then returned to the tower, the rectification efficiency is improved by the gas-liquid equilibrium principle, the energy consumption is reduced, and the solvent recovery rate is improved (more than 95%). The process parameters ensure that the low-boiling-point solvent is separated under mild conditions, avoid the decomposition or polymerization of the solvent caused by high temperature, and ensure the stability of the recovered solvent quality. Compared with the traditional single-stage distillation, the multi-stage rectification significantly reduces the solvent loss, reduces the waste liquid treatment load caused by residual solvent, and reduces the pressure on subsequent inorganic salt wastewater treatment.

[0019] Optionally, it further comprises step (5): freezing crystallization-centrifugal separation of the layered inorganic salt aqueous phase, NaCl crystals are precipitated at-15 DEG C, and the water content of the crystals is less than or equal to 5%.

[0020] By adopting the technical scheme, the freezing crystallization-centrifugal separation process is used for the layered inorganic salt aqueous phase, at-15 DEG C, the solubility of NaCl significantly decreases with the decrease of temperature (the solubility of NaCl is 35.7 g / 100 g water at 0 DEG C, and further decreases at-15 DEG C), which promotes the precipitation of NaCl in the form of crystals. The water content of the crystals is controlled to be less than or equal to 5%, which ensures that the salt concentration in the mother liquor after centrifugal separation is greatly reduced, and the salt load of subsequent wastewater treatment is reduced. Compared with the traditional evaporation crystallization (which requires high-temperature evaporation of water and high energy consumption), the freezing crystallization operates at low temperature, and the energy consumption is reduced by more than 60%, and the corrosion of high temperature to the equipment is avoided. The high-purity NaCl crystals (purity≥98%) can be directly used in the recovery process, reducing the amount of solid waste, and achieving the goal of "reduction" of pollutants.

[0021] Optionally, the freezing crystallization temperature is-18 DEG C to-20 DEG C.

[0022] By adopting the technical scheme, the freezing crystallization temperature is optimized to-18 DEG C to-20 DEG C, further reducing the solubility of NaCl in water (the solubility decreases by about 10% in this temperature range compared with-15 DEG C), promoting more NaCl crystals to precipitate, and improving the crystallization efficiency (the single crystallization rate can be more than 85%). The NaCl crystal particles formed in the low-temperature environment are large, which is convenient for centrifugal separation, reduces the water content of the crystals, ensures that the water content is less than or equal to 5%, and reduces the subsequent drying treatment cost. At the same time, strictly controlling the temperature range can avoid the precipitation of other impurities (such as a small amount of KCl), ensure the purity of NaCl crystals, and lay a foundation for its secondary use. This improvement increases the salt removal rate of inorganic salt wastewater from 70% in the traditional process to more than 90%, significantly reducing the difficulty of wastewater treatment.

[0023] Optionally, the separated NaCl crystals are used for secondary utilization in the agricultural or chemical industry.

[0024] By adopting the above technical scheme, the separated NaCl crystals have high purity and low water content, and can be directly applied to the agricultural (such as adjusting pH value as a soil conditioner) or chemical industry (such as raw material of chlor-alkali industry), realizing the resource recycling of “waste to treasure”. The salt residue produced by treating the NaCl-containing waste liquid in the traditional process is often landfilled as solid waste, which has environmental risks such as heavy metal migration and soil salinization. However, by recycling the crystals, the environmental risks of solid waste landfill are completely eliminated, and additional economic value is created. According to estimates, about 0.8 tons of NaCl can be recovered per ton of T323 produced. According to the price of chemical raw materials, when the annual processing capacity is 50,000 tons, about 2 million yuan of cost can be saved, which has both environmental and economic benefits.

[0025] Optionally, the solid base is selected from sodium hydroxide or potassium hydroxide.

[0026] By adopting the above technical scheme, sodium hydroxide or potassium hydroxide is selected as the solid base, which can efficiently catalyze the synthesis reaction of thiocarbamate due to its strong alkalinity and good thermal stability. The solid form avoids the introduction of a large amount of water by liquid alkali (such as NaOH aqueous solution), reducing the amount of waste liquid from the source (the water content of the traditional liquid alkali process accounts for 40%-50% of the reaction system, and the water content of the process is reduced to less than 10%). At the same time, the cations (Na + , K + ) of the two solid bases combine with the Cl - generated by the reaction to form NaCl or KCl, which is convenient for subsequent freezing and crystallization separation (KCl can be recovered synchronously by adjusting the crystallization conditions), avoiding the separation difficulty caused by the mixture of complex salts, ensuring the single composition of inorganic salts, and improving the recovery efficiency.

[0027] Optionally, the solid base in step (1) is pretreated by ultrafine grinding, and the particle size is ≤20 μm.

[0028] By adopting the above technical scheme, the solid base is ultrafine ground to a particle size of ≤20 μm, which significantly improves its dispersibility and reactivity in ethanol solvent by increasing the specific surface area of the solid base (3-5 times larger than conventional ground particles). The micron-sized particles greatly increase the contact area of the solid base with carbon disulfide and dibutylamine, and the reaction rate is increased by about 30%, shortening the reaction induction period and ensuring that the utilization rate of alkali is increased from 85% in the traditional process to more than 95%, reducing the unreacted alkali entering the waste liquid. At the same time, the uniformly dispersed solid base can inhibit the side reactions (such as the hydrolysis of carbon disulfide to generate H2S) caused by local over-concentration, reduce the waste gas treatment load, and further improve the green level of the process. Ultrafine grinding pretreatment is a key technical link to realize efficient utilization of solid base and reduce alkali residue in waste liquid.

[0029] In a second aspect, the application provides a use of a product produced by a production process for reducing T323 production waste liquid, which uses the following technical solution:

[0030] The product produced by the production process for reducing T323 production waste liquid is applied to turbine oil, hydraulic oil, gear oil, internal combustion engine oil or grease.

[0031] By using the above technical solution, the T323 product produced by the process has a molecular structure consistent with that of the traditional process, and the sulfur content, extreme pressure and wear resistance, and oxidation resistance all meet the industry standards (such as GB / T3536, SH / T0202, etc.). Due to the reduction of impurity introduction and byproduct generation in the production process, the purity of the product is improved by 2%-3% compared with the traditional process, and when applied to oil products such as turbine oil and hydraulic oil, it can more stably play a role in wear resistance and oxidation resistance, extending the service life of the oil product by 5%-10%. At the same time, due to the realization of waste liquid reduction and solvent recovery in the production link, the environmental friendly characteristics of the product are significantly enhanced, meeting the current demand for "green additives" in the lubricating oil industry.

[0032] In summary, the application has the following beneficial effects:

[0033] 1. In the application, solid alkali is used to replace liquid alkali, and ultra-fine grinding is used to improve reaction efficiency, thereby reducing water introduction and byproduct generation from the source, and the concentration of organic matter and salt load in the waste liquid are significantly reduced; the energy consumption of the freezing crystallization process is reduced by more than 60% compared with the traditional evaporation crystallization, the recovery rate of inorganic salt is improved to 90%, and high-salt wastewater reduction treatment and low-cost control are realized.

[0034] 2. In the application, more than 95% of ethanol and hexane solvents are efficiently recovered and reused by multi-stage rectification, a "solvent use-recovery-reuse" closed loop system is constructed, and the consumption of new solvents is reduced by 40%; the separated high-purity NaCl crystals (purity ≥98%) are directly applied to the agricultural or chemical industry, and have both environmental benefits and economic value.

[0035] 3. The method of the application improves the purity of the product by 2%-3% without changing the molecular structure of T323, and the extreme pressure and wear resistance, and oxidation resistance performance are stable and meet the standards, and the service life of the oil product is extended by 5%-10%; the characteristics of no metal residue and low impurity meet the demand for green additives, help downstream industries to meet environmental standards, and enhance market competitiveness. DETAILED DESCRIPTION

[0036] The application will be further described in detail below in conjunction with the examples. It is particularly pointed out that: in the following examples, the specific conditions are not specified, and the conventional conditions or the conditions recommended by the manufacturer are used, and the raw materials used in the following examples can be obtained from ordinary market sources unless otherwise specified.

[0037] Example 1

[0038] A production process for reducing T323 production waste liquid, the specific steps are as follows:

[0039] Raw material preparation and mixing: 600L of industrial ethanol (water content ≤0.1%) is added as a solvent in a 1.5m³ stainless steel reactor, 160kg of solid sodium hydroxide is added, followed by the addition of 140kg of carbon disulfide (purity ≥99%) and 320L of dichloromethane (industrial grade). Start the anchor stirrer (speed 200r / min), mix at room temperature (20-25℃) for 30 minutes, and monitor the dispersion of solid alkali by online particle size analyzer to ensure uniform dispersion.

[0040] Dropwise reaction and temperature control: The reaction system is cooled to 10-12℃ by jacketed refrigerant, 112kg of dibutylamine (purity ≥99%) is added at a rate of 4.67kg / min by metering pump, and the temperature is controlled to be less than 15℃ throughout the process. After the addition is completed, switch the jacket to heating to 75±2℃, and keep the temperature constant for 3.5 hours, during which time take samples every 30 minutes (HPLC monitoring of raw material conversion rate ≥98.5%).

[0041] Product separation: After the reaction is completed, the jacket is cooled to 40-45℃ by circulating water, 480L of industrial hexane (water content ≤0.05%) is added through the pipeline, the shear stirring is started at a speed of 800r / min, and the mixture is stirred for 10 minutes, then it is transferred to a 1.2m³ separation kettle for static separation for 60 minutes. The separation of the lower water phase is detected by the interface instrument, and the upper organic phase is pumped into a distillation column. After recovering hexane under a vacuum of-0.08MPa, T323 product is obtained.

[0042] Example 2

[0043] A production process for reducing T323 production waste liquid, which is different from Example 1 in that the organic phase after separation is subjected to multi-stage rectification to recover the solvent. The organic phase (containing ethanol, hexane and residual dichloromethane) after separation is pumped into a φ800mm stainless steel multi-stage rectification column (filler height 6m, Pall ring filler), the operating pressure is controlled at 0.3MPa (nitrogen pressure stabilization), the column bottom is electrically heated to 90-95℃, and the column top temperature is adjusted to 65±2℃ (corresponding to the ethanol-hexane azeotropic temperature) by a condenser, and the gas phase in the middle of the column is cooled to 50℃ by a plate heat exchanger and then returned (reflux ratio 4:1). The rectification process lasts for 8 hours, and ethanol (recovery rate 96.2%, purity ≥99.5%) and hexane (recovery rate 95.5%, purity ≥98.5%) are separated. After being detected by an online chromatograph to meet the standards, the solvent is returned to the production through a solvent storage tank.

[0044] Example 3

[0045] A production process for reducing T323 production waste liquid differs from Example 1 in that potassium hydroxide is used instead of sodium hydroxide.

[0046] Example 4

[0047] A production process for reducing T323 production waste liquid differs from Example 1 in that the layered aqueous phase is pumped into a 5m3refrigeration crystallizer (inner lining of polytetrafluoroethylene), a screw refrigeration unit is turned on, and crystallization is carried out at -15±1℃ for 24 hours (stirring rate 30r / min). After crystallization is completed, separation is carried out by a siphon centrifuge (drum volume 1.5m3, rotation speed 2500r / min) to obtain NaCl crystals (water content 4.0%, purity 98.8%). The crystals are dried in a vibrating fluidized bed (50℃, air volume 2000m3 / h) and then transported by pneumatic conveying to a chemical raw material storage tank (for the electrolysis process in the chlor-alkali industry), and the mother liquor (salt content <6g / L) is sent to the biochemical system of the plant area sewage treatment station.

[0048] Example 5

[0049] A production process for reducing T323 production waste liquid differs from Example 4 in that the refrigeration crystallization temperature is -19℃.

[0050] Example 6

[0051] A production process for reducing T323 production waste liquid differs from Example 1 in that the solid alkali is pretreated by ultrafine grinding, with a particle size ≤20μm.

[0052] Comparative Example 1

[0053] A production process for reducing T323 production waste liquid differs from Example 1 in that solid sodium hydroxide (particle size ≤20μm) is replaced by a 40% sodium hydroxide aqueous solution.

[0054] Comparative Example 2

[0055] A production process for reducing T323 production waste liquid differs from Example 1 in that ethanol is replaced by toluene (industrial grade, water content ≤0.05%).

[0056] Comparative Example 3

[0057] A production process for reducing T323 production waste liquid differs from Example 1 in that the temperature-controlled <15℃ dropwise addition of dibutylamine is replaced by direct dropwise addition at room temperature (25℃).

[0058] Performance detection test

[0059] Yield calculation: The mass of target product T323 was calculated by gravimetric method based on dibutylamine, and the percentage of the theoretical yield was calculated according to the reaction equation stoichiometry.

[0060] Purity detection: Gas chromatography (GC-FID) was used, with an HP-5 capillary column (30 m x 0.32 mm x 0.25 μm), column temperature program: initial 50°C for 2 min, 10°C / min to 280°C for 5 min, injection port temperature 250°C, detector temperature 280°C, split ratio 10:1, and external standard method was used to calculate the purity (impurities including thiourea, thiocarbonate and other by-products).

[0061] Waste liquid volume: The volume of the aqueous phase was directly measured after separation (accurate to ± 5 L).

[0062] COD concentration: Potassium dichromate method (HJ828-2017), 100 mL of aqueous phase was sampled, acidified with sulfuric acid, and heated to reflux for 2 hours, and the chemical oxygen demand was calculated by titration method.

[0063] NaCl content: Silver nitrate titration method (GB / T11896-1989), 50 mL of aqueous phase was sampled, potassium chromate was used as indicator, and 0.1 mol / L AgNO3 standard solution was used for titration until brick red precipitate appeared.

[0064] Solvent recovery rate: The mass of recovered solvent was calculated by gravimetric method, and the purity was detected by GC (ethanol purity ≥ 99% was considered to meet the standard, and hexane purity ≥ 98%).

[0065] Table 1 detection data

[0066] Product yield (%) Purity (GC, %) Waste liquid volume (L) COD (mg / L) NaCl recovery rate (%) Solvent recovery rate (%) Example 1 92.3 97.8 200 6500 90 95.8 Example 2 92.3 97.8 200 6500 90 96.2 Example 3 93.1 98.0 210 6800 88 95.5 Example 4 92.3 97.8 200 6500 85 95.8 Example 5 92.3 97.8 200 6500 92 95.8 Example 6 92.3 97.8 200 6500 90 95.8 Comparative Example 1 85.2 95.3 520 18000 70 80 Comparative Example 2 88.6 94.8 280 11000 82 85 Comparative Example 3 88.6 94.1 250 12000 85 92

[0067] It can be seen from Example 1 and Comparative Example 1 and Table 1 that when solid sodium hydroxide is replaced by 40% sodium hydroxide aqueous solution, the product yield decreases from 92.3% to 85.2%, the purity decreases from 97.8% to 95.3%, the waste liquid volume increases from 200 L to 520 L, the COD concentration increases from 6500 mg / L to 18000 mg / L, the NaCl recovery rate decreases from 90% to 70%, and the solvent recovery rate decreases from 95.8% to 80%. This shows that the traditional liquid alkali process introduces a large amount of water, which not only reduces the reaction efficiency and increases the generation of by-products, but also significantly increases the waste liquid volume and pollutant concentration. The solid alkali process effectively reduces the introduction of water from the source, improves the product yield and purity, and reduces the waste liquid treatment load.

[0068] It can be seen from Example 1 and Comparative Example 2 in combination with Table 1 that after replacing the solvent ethanol with toluene, the product yield is reduced to 88.6%, the purity is reduced to 94.8%, the waste liquid volume is increased to 280 L, the COD concentration is increased to 11000 mg / L, and the solvent recovery rate is reduced to 85%. This shows that when ethanol is used as a solvent, the homogeneous system formed with dichloromethane and carbon disulfide is more conducive to the dispersion of solid alkali and the progress of the reaction, while toluene has poor compatibility with the reaction system, resulting in a decrease in reaction efficiency, an increase in by-products, and an increase in the difficulty of solvent recovery, further confirming the advantages of ethanol in improving reaction efficiency and environmental friendliness.

[0069] It can be seen from Example 1 and Comparative Example 3 in combination with Table 1 that when the dibutylamine is added without controlling the temperature (at room temperature 25℃), the product yield is reduced to 88.6%, the purity is reduced to 94.1%, the waste liquid volume is increased to 250 L, and the COD concentration is increased to 12000 mg / L. This is because the exothermic side reaction is intensified at room temperature, resulting in excessive hydrolysis of carbon disulfide to form impurities, which not only reduces the purity of the target product, but also increases the content of organic matter in the waste liquid, indicating that the low-temperature dropping process can effectively inhibit side reactions, reduce the generation of pollutants, and improve the cleanliness of the process.

[0070] It can be seen from Example 1 and Comparative Example 2 in combination with Table 1 that after the multi-stage rectification of the organic phase to recover the solvent in Example 2, the solvent recovery rate is increased from 95.8% to 96.2%, while the product yield, purity and waste liquid indicators are consistent with Example 1. This shows that the multi-stage rectification process can achieve efficient recovery of solvents such as ethanol and hexane (recovery rate over 95%) without affecting the core indicators of the reaction, and by building a "solvent recycling" closed-loop system, the consumption of new solvents is greatly reduced, while avoiding the entry of solvents as pollutants into the waste liquid, further strengthening the economic and environmental friendliness of the process.

[0071] It can be seen from Example 1 and Comparative Example 3 in combination with Table 1 that when potassium hydroxide is used instead of sodium hydroxide as a solid alkali, the product yield is slightly increased to 93.1%, the purity is slightly increased to 98.0%, the waste liquid volume is increased to 210 L, the COD concentration is increased to 6800 mg / L, and the NaCl recovery rate is reduced to 88%. This shows that both types of solid alkali can effectively catalyze the reaction, but the generation of potassium salt in the reaction system due to the difference in cations of potassium hydroxide causes a slight decrease in the NaCl recovery efficiency due to the solubility characteristics. However, the overall yield and purity remain at a high level, confirming the flexibility of solid alkali selection, which can be optimized according to the subsequent salt recovery requirements.

[0072] As can be seen from Examples 1, 4, 5 and Table 1, after the freezing crystallization temperature is reduced from -15℃ to -19℃, the NaCl recovery rate is increased from 85% to 92%, while the waste liquid volume, COD and other indicators are consistent with Example 1. This is because a lower temperature further reduces the solubility of NaCl, causing more crystals to precipitate (single crystallization rate is more than 85%), and the crystal particles are larger and have lower water content (≤5%) at low temperature, facilitating centrifugal separation. Compared with traditional evaporation crystallization, the energy consumption is reduced by more than 60%, realizing efficient reduction and resource recovery of inorganic salt wastewater.

[0073] As can be seen from Examples 1, 6 and Table 1, after the solid alkali is pretreated by ultrafine grinding (particle size ≤20μm), the product yield, purity and waste liquid indicators are consistent with Example 1, but from the reaction mechanism, ultrafine grinding increases the specific surface area of solid alkali (3-5 times larger than conventional particles), improves its dispersibility and reactivity in ethanol, and increases the alkali utilization rate from 85% to more than 95%. Although the experimental conditions limit the data in the table to not reflect significant differences, this pretreatment process lays the foundation for inhibiting side reactions and reducing unreacted alkali entering the waste liquid, and is a key link to realize efficient and clean production.

[0074] The specific embodiments are merely an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A process for reducing the production of waste liquor in the production of T323, characterized by, The method comprises the following steps: (1) adding ethanol as a solvent, solid alkali, carbon disulfide and dichloromethane, and mixing at room temperature; (2) controlling the temperature to be less than 15 ℃, adding dibutylamine dropwise, and then increasing the temperature to 70-80 ℃ for reaction for 3 hours; (3) cooling to below 50 ℃, adding an extraction solvent hexane, and separating to obtain T323 products; (4) introducing the organic phase after separation of T323 into a multi-stage rectifying tower, controlling the operation pressure of the rectifying tower to be 0-0.5 MPa, the column bottom temperature to be 60-150 ℃, and the column top temperature to be 40-80 ℃, cooling the gas phase flow in the middle of the tower to 40-60 ℃, and returning the gas phase flow into the tower to separate and recover ethanol and hexane mixed solvents; (5) performing freeze crystallization-centrifugal separation on the inorganic salt aqueous phase after separation, precipitating NaCl crystals at-15 ℃, and the water content of the crystals being less than or equal to 5%; the freeze crystallization temperature is-18 ℃ to-20 ℃.

2. The process for reducing production of T323 production waste liquor according to claim 1, characterized in that: The separated NaCl crystals are used for secondary use in the fields of agriculture or chemical industry.

3. The process for reducing production of T323 production waste liquor according to claim 1, characterized in that: The solid alkali is selected from sodium hydroxide or potassium hydroxide.

4. The process for reducing production of T323 production waste liquor according to claim 1, characterized in that: The solid alkali in step (1) is pretreated by ultrafine grinding, and the particle size is less than or equal to 20 μm.