Sulfonylurea herbicide reaction filtration washing and drying machine

Sulfonylurea herbicides are mainly a type of highly efficient herbicides that developed in the 1980s. This type of herbicide features high herbicidal activity and low dosage (2 to 100g/hm2). Currently, there are over 30 commercialized varieties. In 2003 alone, the annual sales of this type of herbicide reached 1.63 billion US dollars, accounting for 12.2% of the total global sales of herbicides.

In the production of sulfonylurea herbicides, 2-amino-4, 6-dimethoxylpyrimidine is an important intermediate for their synthesis. There are many varieties of herbicide raw materials synthesized from it, such as mesotrione, benzylmesotrione, pyrimetrione, pyrimetrione, almetrione, ethoxymesotrione, and phthalmetrione, etc.

Analysis of the Post-treatment Process for sulfonylurea Herbicide intermediates

Among the mainstream preparation methods of ADMP at present, the process route using malonitrile as the raw material has always been a key focus. In the aromatization cyclization reaction step, a solvent-free method is adopted. The crude product obtained is then subjected to high vacuum distillation, followed by the introduction of organic solvents as dispersants for crystallization and granulation, thereby obtaining the pure product. This scheme has low cost and simple operation, and has played a practical role in promoting the industrial implementation of existing processes. The selection of dispersants mainly focuses on common organic solvents such as toluene and xylene. However, during the industrial implementation process, the following drawbacks were still found:

(1) Increase production costs. The dispersant has a certain solubility for the product, resulting in product loss. At the same time, it needs to be recycled and reused, generating operating costs.

(2) There are potential safety hazards. During the filtration and drying processes of toluene-based organic solvents, due to their inherent flammability and low flash point, there are hidden concerns such as potential fire hazards.

(3) There are certain environmental protection pressure issues. Due to the large amount of toluene-based dispersants used, during the application process (such as product filtration, dispersant recovery and mother liquor treatment, etc.), their volatilization and leakage will occur, increasing the pollution of volatile organic compounds (VOC, volatile organic compounds) to the factory environment and affecting the health of the workers.

The cylindrical and conical reaction filtration and drying multi-functional machine developed by Wuxi Srui is multi-functional. It can complete various operations such as reaction, extraction and crystallization, filtration, repeated filtration and washing, and drying in one machine, and directly obtain finished products. Its unique superiority meets the post-treatment process requirements for obtaining pure 2-amino-4, 6-dimethoxylpyrimidine with simple operation, zero pollution, high yield and high quality.

The process flow of sulfonylurea herbicide reaction, filtration, washing and drying machine

(1) Stirring reaction: This machine adopts a cylindrical and conical structure, allowing for constant-temperature and timed reactions of heating or cooling materials within the machine. After distillation and cooling, pure water and stabilizer are added to the product, and it is heated to 75℃ - 95℃ to melt. Then, while stirring, it is slowly cooled to 30℃ - 50℃

(2) Pressure filtration or vacuum filtration: After the reaction is completed, the filtrate is filtered through pressure filtration or vacuum suction filtration. During the filtration stage, due to the good adhesion and scraping effect between the helical ribbon and the filter medium, the material can be filtered under the condition of a thin filter cake, with high filtration efficiency.

(3) Multiple washing and filtration are possible: After the material is filtered and dried, washing liquid can be added and it can undergo multiple automatic reactions and mixes with the material inside the machine before washing. After the washing and filtration meet the washing requirements, it can be filtered and dried again.

(4) Vacuum drying and discharging: After the material is filtered and dried, it is heated simultaneously in the jacket of the drying section cylinder, the hollow shaft and the screw ribbon. A vacuum is then applied at the top for vacuum low-temperature sealed drying of the material. The dried material is automatically sealed and discharged. After the filter cake is dried, a pure white granular product of 2-amino-4, 6-dimethoxypyrimidine is obtained.

The multi-functional equipment for reaction, filtration, washing and drying of sulfonylurea herbicide intermediates has improved the preparation effect of ADMP by enhancing the equipment structure and optimizing the process flow. It occupies less space, has a low cost, is convenient for production and processing, reduces labor intensity and greatly reduces material loss. Moreover, it is particularly suitable for operations that are toxic, flammable, explosive or have extremely high sealing requirements, and has almost no impact on workers' health or the surrounding environment.