Method for producing crude 2B acid

Abstract

The invention discloses a crude product 2B acid production method, and relates to the technical field of 2B acid preparation, and the method comprises the following steps: S1, adding 2B oil and a D60 solvent into a sulfonation kettle according to a mass ratio of 1: 2-4, and carrying out a sulfonation reaction to obtain a sulfonation reactant; s2, the sulfonation reactant is moved into a baking kettle for baking transposition, and dried powder is obtained; s3, mechanically crushing the dried powder to obtain 2B acid crude fine powder; s4, adding the 2B acid crude fine powder and organic alcohol into extraction equipment according to the mass ratio of 1: (2-5) for extraction, and carrying out solid-liquid separation on extract liquor through a filter cloth dehydration device to obtain a preliminarily dehydrated wet solid; s5, carrying out flash evaporation drying on the preliminarily dehydrated wet solid to obtain a crude product 2B acid with high purity; according to the method disclosed by the invention, the step of extracting and washing with the organic alcohol is added after crushing, so that the 2B oil can be transferred to a liquid phase and is filtered and separated, the residual quantity of the 2B oil in the finally obtained crude product 2B acid is greatly reduced, and the purity is obviously improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic pigment intermediate preparation, and particularly relates to a production method of crude 2B acid. BACKGROUND

[0002] 2B acid (2-amino-5-chloro-4-methylbenzenesulfonic acid) as an important organic intermediate has irreplaceable application value in the fields of dyes, pigments, and pharmaceuticals. In industrial application scenarios, 2B acid is divided into 2B acid crude and 2B acid fine according to the complexity of the production process and the purity requirement. Among them, 2B acid crude is widely used due to the advantages of simplified production process, lower equipment investment, controllable energy consumption and raw material cost.

[0003] At present, 2B acid crude is produced by using 2B oil and sulfuric acid as main raw materials in the presence of a solvent, and then subjected to sulfonation and baking conversion, and then crushed into fine powder for packaging. Since the raw material is in liquid phase and the sulfonation product is in solid phase, the production reaction is a heterogeneous reaction, so the mixed solvent of D60, dichlorobenzene and trichlorobenzene is used as a dispersion phase to improve the uniformity of material mixing in the heterogeneous reaction system and to improve the reaction rate and raw material conversion rate.

[0004] However, even if the mixed solvent of D60, dichlorobenzene and trichlorobenzene is used as a dispersion phase, it is still difficult to avoid the phenomenon of small amount of agglomeration of solid materials in the baking conversion stage. The block-shaped material formed by agglomeration is easy to form a closed area inside, which causes the raw material in the area to be unable to fully contact with the sulfonating agent, resulting in incomplete reaction, and finally causing the residual unreacted 2B oil raw material in the finished 2B acid crude. The residual 2B oil raw material not only affects the color stability and coloring intensity of the downstream dye product, but also may generate by-products in the subsequent reaction, increasing the difficulty and cost of the downstream purification process. SUMMARY

[0005] The purpose of the present application is to provide a production method of crude 2B acid, which can improve the purity of 2B acid crude to solve the problems raised in the background.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] A production method of crude 2B acid, comprising the following steps:

[0008] S1, 2B oil and D60 solvent are added into a sulfonation kettle in a mass ratio of 1:2-4 for sulfonation reaction to obtain a sulfonation reaction product;

[0009] S2, the sulfonation reaction product is moved into a baking kettle for baking conversion to obtain a dried powder, wherein the solvent evaporated in the baking conversion is first cooled and stored in a circulating water column cooler, and then the stored solvent is returned to the sulfonation kettle.

[0010] S3, the dried powder is mechanically pulverized to obtain 2B acid crude powder;

[0011] S4, the 2B acid crude powder and organic alcohol are added into an extraction device in a mass ratio of 1:2-5 for extraction, and the extraction liquid is subjected to solid-liquid separation through a filter cloth dehydration device to obtain wet solid after preliminary dehydration;

[0012] S5, the wet solid after preliminary dehydration is subjected to flash drying to obtain crude 2B acid with high purity.

[0013] Preferably, the sulfonation reaction process is as follows:

[0014] A1, D60 solvent is added into a sulfonation kettle, then 2B oil is added into the sulfonation kettle, and finally a sufficient amount of sulfuric acid with a concentration of 98% is prepared in a sulfuric acid high tank, and the amount of sulfuric acid is calculated according to 1:1 of the molar amount of 2B oil, and the weight is 0.762*2B oil weight;

[0015] A2, the raw materials in the sulfonation kettle are stirred at a speed not exceeding 90 rpm, and sulfuric acid is added dropwise into the sulfonation kettle at a speed not exceeding 10 kg / min, and the temperature is not higher than 120°C during dropwise addition;

[0016] A3, after the dropwise addition is completed, the temperature is raised to 120-140°C for dehydration, and the dehydration is continued until no water vapor is generated, and then the reaction is terminated.

[0017] Preferably, the reaction conditions during the baking and shifting are as follows: the temperature is 180-185°C, and the holding time is 5±0.2 hours, after the shifting reaction is completed, the baking kettle is vacuumized to -0.02 to -0.05 Mpa, and the solvent is evaporated at 180±2°C until no solvent is discharged.

[0018] Preferably, the circulating water column cooler uses industrial circulating water as the cooling medium, and the cooling water flow rate is 1-2 m / s.

[0019] Preferably, a hammer crusher is used for mechanical pulverization, and the screen mesh aperture of the hammer crusher is 0.1-0.3 mm.

[0020] Preferably, the organic alcohol is methanol or ethanol, and a paddle stirrer is used for stirring for 15 minutes during extraction to fully suspend the powder, and the gap between the stirring paddle of the paddle stirrer and the kettle wall is 5-10 mm.

[0021] Preferably, the filter cloth dehydration device includes a rack, a power shaft driven rubber belt with drainage holes, and filter cloth covering the rubber belt, and the alcohol is sucked away through the filter cloth and the rubber belt holes by vacuum suction to obtain wet solid.

[0022] Preferably, the wet solid is dried by rotary flash drying at 150 DEG C, the hot air inlet temperature of the flash dryer is 180-200 DEG C, and the outlet temperature is controlled at 80-100 DEG C.

[0023] Preferably, the alcohol containing 2B oil after extraction is subjected to alcohol recovery by distillation, the recovered alcohol can be recycled for extraction, the separated 2B oil can be reused as raw material, and the alcohol containing 2B oil is subjected to alcohol recovery by distillation under normal pressure, the number of plates of the distillation column is 15-20, and the reflux ratio is controlled at 1-2:1.

[0024] Preferably, the sulfonation kettle and the baking kettle are both made of 316L stainless steel, and the inner wall of the kettle is subjected to polishing treatment, and the polishing roughness Ra is less than or equal to 0.8 microns.

[0025] Compared with the prior art, the production method of the crude 2B acid has the following advantages:

[0026] 1. The D60 solvent used in the sulfonation stage is subjected to baking and conversion, and then is evaporated by vacuum distillation, and then is reused in the sulfonation process after cooling; the methanol or ethanol used for extraction is subjected to recovery by distillation, and then is reused for extraction, and the separated 2B oil can be reused as raw material, which not only reduces the waste of solvent and raw material, reduces the production cost, but also reduces the waste discharge, and meets the clean production requirement.

[0027] 2. The sulfonation, baking and conversion, extraction and filter cloth dehydration device combined with rotary flash drying ensure complete solid-liquid separation and uniform drying, effectively avoid the problem of material agglomeration, and improve the product uniformity.

[0028] 3. The organic alcohol extraction and washing step is added after crushing, the 2B oil is transferred to the liquid phase and separated by filtration, the residual amount of 2B oil in the crude 2B acid obtained finally is greatly reduced, and the purity is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The preparation flow chart of the present application is shown in the figure;

[0030] Figure 2 The structure schematic diagram of the sulfonation kettle of the present application is shown in the figure;

[0031] Figure 3 The structure schematic diagram of the baking kettle of the present application is shown in the figure;

[0032] Figure 4 The structure schematic diagram of the extraction equipment of the present application is shown in the figure;

[0033] Figure 5 The structure schematic diagram of the filter cloth dehydration device of the present application is shown in the figure;

[0034] In the diagram: 1. Sulfonation kettle; 2. High-level sulfuric acid tank; 3. Dropping control valve; 4. Baking kettle; 5. Receiving tank; 6. Circulating water tube cooler; 7. Extraction equipment; 8. Alcohol inlet; 9. Powder inlet; 10. Extraction liquid outlet; 11. Frame; 12. Conveyor belt; 13. Filter cloth; 14. Feed inlet; 15. Tail gas collection port; 16. Wet solids discharge port; 17. Drain port. Detailed Implementation

[0035] 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 specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention provides, for example Figures 1-5 The method for producing crude 2B acid shown includes the following steps:

[0037] S1. Add 2B oil and D60 solvent to sulfonation reactor 1 at a mass ratio of 1:2-4 to carry out sulfonation reaction and obtain sulfonated product;

[0038] The sulfonation reaction process is as follows:

[0039] A1. Add D60 solvent to sulfonation kettle 1, then add 2B oil to sulfonation kettle 1, and finally prepare sufficient sulfuric acid with a concentration of 98% in the high-level sulfuric acid tank. The amount of sulfuric acid added is calculated according to the molar amount of 2B oil at a 1:1 ratio, and the weight is 0.762 * the weight of 2B oil.

[0040] A2. Stir the raw materials in sulfonation kettle 1 at a speed not exceeding 90 rpm, and add sulfuric acid dropwise to sulfonation kettle 1 at a speed not exceeding 10 kg / min, with the temperature not exceeding 120℃ during the dropwise addition.

[0041] A3. After the addition is complete, heat to 120-140℃ for heat preservation and dehydration until almost no water evaporates, then end the heat preservation reaction.

[0042] like Figure 2 As shown, the upper end of the sulfonation reactor 1 is equipped with an oil inlet pipe and a solvent inlet pipe (2B), the lower end of the sulfonation reactor 1 is equipped with a transfer pipe, and the upper end of the sulfonation reactor 1 is connected to a high-level sulfuric acid tank 2 via a pipeline. A dripping control valve 3 is installed on the pipeline connecting the high-level sulfuric acid tank 2 and the sulfonation reactor 1. The dripping control valve 3 controls the flow rate of sulfuric acid dripping into the sulfonation tank. A stirrer is installed inside the sulfonation reactor 1.

[0043] The equation for the sulfonation reaction of oil 2B with sulfuric acid is as follows:

[0044] .

[0045] S2, the sulfonated reactant is moved into the baking kettle 4 for baking conversion, and a dried powder is obtained, wherein the solvent evaporated in the baking conversion is first cooled and stored in the circulating water column cooler 6, and then the stored solvent is returned to the sulfonation kettle 1;

[0046] As shown in Figure 3 , the upper end of the baking kettle 4 is communicated with the circulating water column cooler 6 through a pipeline, the lower end of the circulating water column cooler 6 is communicated with a receiving tank 5 for solvent storage, the upper end of the receiving tank 5 is provided with a vacuum extraction pipeline, the upper end of the baking kettle 4 is provided with a sulfonated material inlet pipe, and the lower end is provided with a powder outlet;

[0047] The reaction conditions during the baking conversion are as follows: temperature 180-185℃, holding time 5±0.2 hours, after the conversion reaction is completed, the baking kettle 4 is vacuumized to -0.02 to -0.05Mpa, and the solvent is evaporated at 180±2℃ until no solvent is discharged.

[0048] The circulating water column cooler 6 uses industrial circulating water as the cooling medium, and the flow rate of the cooling water is 1-2m / s;

[0049] The sulfonation kettle 1 and the baking kettle 4 are both made of 316L stainless steel, and the inner wall of the kettle is polished to a roughness Ra≤0.8μm to prevent the material from sticking to the kettle wall;

[0050] S3, the dried powder is mechanically pulverized to obtain 2B acid crude powder;

[0051] In the mechanical pulverization, a hammer crusher is used for pulverization, the screen mesh aperture of the hammer crusher is 0.1-0.3mm, and the particle size uniformity of the 2B acid crude powder after pulverization is ensured to be within ±0.05mm;

[0052] S4, the 2B acid crude powder and the organic alcohol are added into the extraction equipment 7 in a mass ratio of 1:2-5 for extraction, the extraction liquid is subjected to solid-liquid separation through a filter cloth 13 dehydration device to obtain a preliminarily dehydrated wet solid;

[0053] As shown in Figure 4 , the extraction equipment 7 includes an extraction tower, the upper end of the extraction tower is provided with an alcohol inlet 8 and a powder inlet 9 on both sides, the lower end of the extraction tower is provided with an extraction liquid outlet 10, and a paddle agitator is arranged in the extraction tower to improve the uniformity of the material mixing in the extraction tower;

[0054] The organic alcohol is methanol or ethanol, and a paddle stirrer is used to stir for 15 minutes during extraction to fully suspend the powder, the gap between the stirring paddle of the paddle stirrer and the wall of the kettle is 5-10 mm to avoid accumulation of the powder on the wall of the kettle;

[0055] As shown in Figure 5 Fig. 1, the filter cloth 13 dewatering device includes a rack 11, a power shaft driven belt conveyor 12 with drainage holes and a filter cloth 13 covering the belt conveyor 12, the rack 11 is provided with a feeding port 14, one side of the feeding port 14 is provided with a tail gas collecting port 15, a liquid discharge port 17 is arranged below the upper belt conveyor 12, and one end of the rack 11 is provided with a wet solid discharging port 16. The alcohol is extracted through the filter cloth 13 and the holes of the rubber belt by vacuum suction, and the wet solid is obtained. The filter cloth 13 of the filter cloth 13 dewatering device is made of polyester, the pore size of the filter cloth 13 is 5-10 μm, and the filter cloth 13 can be regularly disassembled and cleaned, and the cleaning cycle is once every 8 hours of continuous operation.

[0056] S5, the wet solid after primary dewatering is flash dried to obtain a high-purity crude 2B acid;

[0057] The wet solid is dried by rotary flash drying at 150°C to obtain the crude 2B acid. The hot air inlet temperature of the flash dryer is 180-200°C, and the outlet temperature is controlled at 80-100°C to ensure that the water content of the dried crude 2B acid is less than 0.5%. The alcohol containing 2B oil after extraction is distilled to recover the alcohol, the recovered alcohol can be recycled for extraction, and the separated 2B oil can be reused as raw material. When the alcohol of the 2B oil is distilled and recovered, atmospheric distillation is used, the number of plates of the distillation column is 15-20, and the reflux ratio is controlled at 1-2:1 to make the purity of the recovered alcohol not less than 95%.

[0058] The D60 solvent used in the sulfonation stage is baked and converted after being used, and can be distilled by vacuum distillation, and then reused in the sulfonation process after cooling. The methanol or ethanol used for extraction can be repeatedly used for extraction after being recovered by distillation, and the separated 2B oil can also be reused as raw material, which not only reduces the waste of solvent and raw material, reduces production cost, but also reduces waste emissions, meets the requirements of clean production, and through sulfonation, baking and conversion, extraction and the use of filter cloth 13 dewatering device combined with rotary flash drying, it ensures that the solid-liquid separation is complete and the drying is uniform, effectively avoids the problem of material agglomeration, and improves the product uniformity. After crushing, the organic alcohol extraction and washing step can transfer the 2B oil to the liquid phase and separate it by filtration, and the residual amount of 2B oil in the final crude 2B acid is greatly reduced, and the purity is significantly improved.

[0059] To verify the purity of the crude 2B acid prepared by the above provided crude 2B acid production method, the following specific examples are provided:

[0060] Example 1

[0061] A method for producing crude 2B acid, comprising the following steps:

[0062] Sulfonation reaction step

[0063] A 316L stainless steel sulfonation kettle with a specification of 1000L is prepared, the inner wall of the kettle is polished, the roughness Ra=0.6μm, first, 2 times the weight of 2B oil is added to the kettle D60 solvent, if 200kg of 2B oil is added subsequently, 400kg of D60 solvent is added, the stirring device is started, the stirring paddle is paddle type, the gap between the paddle and the kettle wall is 8mm, and the stirring speed is controlled at 80rpm;

[0064] 200kg of 2B oil with a purity of ≥98% is added to the sulfonation kettle, and 98% sulfuric acid with a concentration of 98% is prepared in the sulfuric acid high tank, and the weight of sulfuric acid is 0.762×200kg=152.4kg according to the molar ratio of 2B oil to sulfuric acid 1:1;

[0065] Sulfuric acid is added to the sulfonation kettle through the sulfuric acid dropping pipeline, the dropping rate is controlled at 8kg / min, and the temperature is monitored in real time through the temperature sensor in the kettle during the dropping process, if the temperature approaches 120℃, the dropping rate is appropriately reduced to ensure that the dropping temperature does not exceed 120℃;

[0066] After the dropping is completed, the temperature in the kettle is raised to 130℃ by the heating device, and dehydration is carried out; during the dehydration process, the water vapor is collected through the gas phase outlet pipeline, the amount of water vapor is observed, and when the amount of water vapor is continuously less than 0.1kg / h for 30min, it is determined that there is basically no water vapor, and the sulfonation reaction is ended, at this time, the sulfonation product 2 is obtained in the kettle;

[0067] Baking and indexing step

[0068] The sulfonation product is moved into a 316L stainless steel baking kettle with a specification of 1000L through a conveying pump, the inner wall of the baking kettle is polished, the roughness Ra=0.6μm, the heating device of the baking kettle is started, the temperature is raised to 182℃, and the indexing reaction is carried out for 5h;

[0069] After the indexing reaction is completed, the vacuum system of the baking kettle is started, the vacuum degree in the kettle is extracted to-0.03MPa, the temperature in the kettle is maintained at 180℃, and the D60 solvent in the kettle is evaporated; the evaporated D60 solvent is introduced into a circulating water column cooler through a solvent outlet pipeline, industrial circulating water is introduced into the cooler, the flow rate is 1.5m / s, the solvent is cooled to below 45℃, and then stored in a solvent receiving tank for subsequent sulfonation process; when the amount of solvent collected in the solvent receiving tank does not increase continuously for 30min, it is determined that there is no solvent distillation, and the vacuum distillation is stopped, at this time, the dried powder material is obtained in the baking kettle;

[0070] Pulverization treatment step

[0071] The powder material in the baking kettle is moved into a hammer crusher, the screen aperture is 0.2 mm, the crusher is started to mechanically crush, the particle size of the powder is monitored in real time by a particle size detector during the crushing process, the uniformity of the particle size of the 2B acid crude powder after crushing is ensured to be within ±0.05 mm, and the fine powder is collected after crushing for later use.

[0072] Extraction, washing and separation and drying steps

[0073] 100 kg of the crushed 2B acid crude powder is added into an extraction kettle with a specification of 500 L, and 3 times the weight of the fine powder, i.e. 300 kg of methanol, is added, the stirring device is started, the stirring paddle is a paddle type, the gap between the paddle and the kettle wall is 8 mm, the stirring speed is controlled at 100 rpm, and the powder is fully suspended in the methanol after stirring for 15 min;

[0074] The discharge valve at the bottom of the extraction kettle is opened, and the solid-liquid mixture is transported to a filter cloth dewatering device; the device is provided with a power shaft driven rubber conveyor belt with a thickness of 2 cm and a drainage hole with a diameter of 5 mm at the center, and the conveyor belt is covered with polyester filter cloth with a pore size of 8 μm; the vacuum system of the device is started, and the methanol is pumped away through the filter cloth and the drainage hole of the rubber belt by vacuum suction, the pumped methanol is stored in an intermediate storage tank, and the wet solid in the kettle is preliminarily dewatered; the filter cloth is disassembled and cleaned every 8 h of continuous operation to ensure the filtering effect;

[0075] The wet solid is sent into a rotary flash drying machine, the hot air inlet temperature of the flash drying machine is set to 190 ℃, the outlet temperature is 90 ℃, and the drying temperature is controlled at 150 ℃, and the wet solid is dried; after drying, sampling detection is performed to ensure that the water content of the crude 2B acid after drying is less than 0.5%, and then the finished product is packaged;

[0076] The methanol containing 2B oil in the intermediate storage tank is sent into an atmospheric distillation column, the column plate number is 18, and the reflux ratio is controlled at 1.5:1, and distillation recovery is performed; after distillation, the purity of the recovered methanol is 96%, which can be reused in the extraction process; the 2B oil with a purity of ≥97% collected at the bottom of the distillation column is stored in a raw material storage tank as the 2B oil raw material for subsequent production.

[0077] Example 2

[0078] The same parts are not repeated, and the difference from Example 1 is that ethanol is used instead of methanol in the extraction and washing step, specifically: 400 kg of ethanol is added to 100 kg of 2B acid crude powder, which is 4 times the weight of the fine powder, and the solid-liquid separation is performed after stirring for 15 min; the ethanol containing 2B oil is recovered by atmospheric distillation, the column plate number of the distillation column is 16, the reflux ratio is 1:1, the purity of the recovered ethanol is 95.5%, and the remaining sulfonation, baking, transposition, crushing and drying steps are consistent with Example 1. The water content of the crude 2B acid obtained is 0.45%, and the residual amount of 2B oil is less than 0.05%.

[0079] From the above examples, it can be seen that the production method of the present application can stably produce high-purity crude 2B acid, and the solvent and raw materials can be recycled.

[0080] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the scope of the present application should be included in the protection scope of the present application.

Claims

1. A process for the production of crude 2B acid, characterized by: Comprise the following steps: S1, 2B oil and D60 solvent are added into a sulfonation kettle in a mass ratio of 1:2-4 for sulfonation reaction to obtain a sulfonation reactant; S2, the sulfonation reactant is moved into a baking kettle for baking and transposition to obtain a dried powder, wherein the solvent evaporated in the baking and transposition is first cooled and stored in a circulating water column cooler, and then the stored solvent is returned to the sulfonation kettle; S3, the dried powder is mechanically pulverized to obtain a 2B acid crude powder; S4, the 2B acid crude powder and an organic alcohol are added into an extraction device in a mass ratio of 1:2-5 for extraction, and the extraction liquid is subjected to solid-liquid separation through a filter cloth dehydration device to obtain a preliminarily dehydrated wet solid; S5, the preliminarily dehydrated wet solid is subjected to flash drying to obtain a high-purity 2B acid crude product.

2. The method for producing crude 2B acid according to claim 1, characterized by: The sulfonation reaction process is as follows: A1, the D60 solvent is added into the sulfonation kettle, then the 2B oil is added into the sulfonation kettle, and finally a sufficient amount of sulfuric acid with a concentration of 98% is prepared in a sulfuric acid high tank, and the amount of the sulfuric acid is converted at a ratio of 1:1 based on the molar amount of the 2B oil, and the weight is 0.762*2B oil weight; A2, the raw materials in the sulfonation kettle are stirred at a stirring speed of not more than 90 rpm, and the sulfuric acid is added dropwise into the sulfonation kettle at a speed of not more than 10 kg / min, and the temperature is not more than 120°C during the dropping; A3, after the dropping is completed, the temperature is raised to 120-140°C for heat preservation and dehydration, and the heat preservation reaction is ended until no water vapor is evaporated.

3. The method for producing crude 2B acid according to claim 2, characterized by: The reaction conditions in the baking and transposition are as follows: the temperature is 180-185°C, the heat preservation time is 5±0.2 hours, after the transposition reaction is completed, the baking kettle is vacuumized to-0.02 to-0.05 Mpa, and the solvent is evaporated at 180±2°C until no solvent is outflowed.

4. The method for producing crude 2B acid according to claim 3, characterized by: The circulating water column cooler uses industrial circulating water as the cooling medium, and the cooling water flow rate is 1-2 m / s.

5. The method for producing crude 2B acid according to claim 4, wherein: In the mechanical pulverization, a hammer crusher is used, and the screen mesh aperture of the hammer crusher is 0.1-0.3 mm.

6. The method for producing crude 2B acid according to claim 5, wherein: The organic alcohol is methanol or ethanol, and in the extraction, a paddle stirrer is used to stir for 15 minutes to make the powder fully suspended, and the gap between the stirring paddle of the paddle stirrer and the kettle wall is 5-10 mm.

7. The method for producing crude 2B acid according to claim 6, wherein: The filter cloth dehydration device comprises a rack, a power shaft driven rubber conveyor belt with drainage holes and filter cloth covering the conveyor belt, and the alcohol is sucked away through the filter cloth and the rubber belt holes by a vacuum suction method to obtain a wet solid.

8. The method for producing crude 2B acid according to claim 7, wherein: The wet solid is subjected to rotary flash drying at 150°C to obtain a 2B acid crude product, the hot air inlet temperature of the flash drying machine is 180-200°C, and the outlet temperature is controlled at 80-100°C.

9. The method for producing crude 2B acid according to claim 8, wherein: After the extraction, the alcohol containing 2B oil is subjected to alcohol distillation recovery, the recovered alcohol can be recycled for extraction, the separated 2B oil can be reused as a raw material, and in the alcohol distillation recovery of the 2B oil, atmospheric distillation is used, the number of plates of the distillation column is 15-20, and the reflux ratio is controlled at 1-2:

1.

10. The method for producing crude 2B acid according to claim 1, wherein: The sulfonation kettle and the baking kettle are made of 316L stainless steel, and the inner wall of the kettle is polished, and the polishing roughness Ra is ≤0.8 μm.

Images