Glufosinate-ammonium is one of the large-tonnage pesticide varieties in the world. Compared with glyphosate, glufosinate-ammonium has a better effect on removing some perennial malignant weeds, and is more competitive in the field of high economic value crops. As an excellent herbicide, glufosinate-ammonium is very suitable as a resistance gene.
These genetically modified crops are not only commonly planted in North America, but also in some countries and regions such as Asia, Australia, and Europe in recent years. With the rapid development of transgenic technology, the market prospect of glufosinate-ammonium is very promising.
The existing purification process of the new herbicide glufosinate-ammonium
(1) Preparation of concentrate
After the 1-(methylethoxyphosphono)-butyronitrile solution is hydrochloric acid refluxed acidolysis, the glufosinate-ammonium hydrochloride reaction solution is obtained, and then the glufosinate-ammonium hydrochloride reaction solution is distilled off under reduced pressure to remove dilute hydrochloric acid to obtain Concentrated solution A; add ammonia water to the concentrated solution A, adjust the pH to 5-10, heat up and continue to heat and stir after dispersing evenly, and then distill under reduced pressure to remove water to obtain concentrated solution B;
(2) Crude crystallization and solid-liquid separation of glufosinate-ammonium
Add the flotation solvent alcohol to the concentrated solution B, heat up and disperse evenly, then cool down, and then continue to stir until the material is evenly dispersed; at the flotation temperature of 15-50°C, slowly put the evenly stirred material into the chute, and the material passes through After the chute, due to the difference in specific gravity between the main component and the secondary salt, 10% to 30% of the main component particles are brought to the collection tank with the flow of the flotation solvent alcohol, while 70% to 90% of the secondary salt particles are settled due to the specific gravity to the chute; the secondary salt on the chute is collected and separated from solid and liquid;
(3) Glufosinate-ammonium purification, filtration, washing and drying
The filter cake is washed twice with flotation solvent alcohol, and the filtrate is mixed with the alcohol solution containing the main component in the collection tank; the alcohol solution containing the main component in the collection tank is transferred to the recovery kettle for distillation and desolvation under reduced pressure, and then add water-containing methanol After the temperature rises and the dispersion is uniform, the pH is adjusted to be greater than or equal to 8 by passing ammonia, the temperature is lowered, the solid and liquid are separated, the filter cake is washed twice with aqueous methanol and then dried to obtain the final product glufosinate-ammonium.
Technical problems of existing synthesis and purification process of glufosinate-ammonium
The production process of glufosinate-ammonium is complicated. It takes more than half a month to produce the product through 13 reaction processes. It has the characteristics of large investment, complicated production process, high technical requirements, high safety pressure, and strict environmental protection requirements.
(1) The safety control of raw materials and process reactions is difficult
The existing synthesis process of glufosinate-ammonium involves more than ten kinds of chemical raw materials, most of which are flammable, explosive, and have low flash point chemical characteristics, especially sodium cyanide is a highly toxic substance, and a little carelessness will cause safety accidents . At the same time, multiple steps of the process need to be carried out in a strictly anhydrous and oxygen-free airtight environment.
(2) Large discharge of three wastes
The synthesis route is relatively long, subdivided into more than a dozen operating units such as distillation, rectification, and filtration, and each unit will produce corresponding three wastes, which are difficult to deal with and increase the pressure on environmental protection. For every ton of glufosinate-ammonium technical product produced, the amount of process wastewater produced is about 60 tons. Most of the wastewater needs to be evaporated to dryness to obtain waste residues. Some waste residues and crystallization leftovers are difficult to reuse.
(3) The product yield is low
Compared with Bayer in Germany, the cost of domestic production of glufosinate-ammonium is relatively high, and it has no price advantage in the international market.
(4) Failure to achieve continuous and automated production, high investment in production line equipment
Compared with foreign countries, there is a certain gap in the quality of glufosinate-ammonium technical products produced by domestic enterprises. They have higher requirements for production equipment and need to invest a lot of money in maintenance of equipment.
Key equipment for automatic production of new herbicide glufosinate-ammonium New type of cylinder cone filter washing two-in-one
The function of the filtration and washing equipment is to separate the solid-liquid separation of the crude glufosinate-ammonium slurry obtained by the reaction, and then use the washing liquid to wash the obtained glufosinate-ammonium filter cake to remove ammonium chloride and inorganic salts remaining in the filter cake , Other by-products. At present, most glufosinate-ammonium manufacturers use integrated filtration and washing equipment, mainly including filter presses, centrifuges, microporous filters, new cylinder-cone filtration and washing two-in-one equipment, etc.
(1) filter press
Filter press is a commonly used filtering and washing equipment. Traditional filter presses generally require manual operation of the entire filtration process, including feeding, pressing, air blowing, and unloading. Especially unloading is labor-intensive, the filter cake is difficult to remove, the entire filter press cycle is long, the processing capacity is small, dehydration and The washing effect is poor, and the material is usually cast iron, which is heavy and easy to wear.
In recent years, the technical level of the filter press has been greatly improved, and the automatic filter press has been well applied. The entire filter press process is automatically controlled. The material is made of stainless steel or synthetic materials, and the filter chamber is enlarged and enlarged in structure. Diaphragm design, and increased filtration pressure, large processing capacity, short filter press cycle, high dehydration efficiency, good washing effect, can meet the production requirements of glufosinate-ammonium purification.
(2) Centrifuge
A centrifuge is a machine that uses centrifugal force to separate liquid and solid particles or different components in a liquid mixture. The core component of a centrifuge is the bowl, a cylinder that rotates at high speed around its own axis, usually driven by an electric motor. After the solid-liquid mixture enters the drum, it is quickly driven to rotate at the same speed as the drum, and the solid and liquid are separated under the centrifugal force, the solid particles are intercepted on the inner wall of the drum, and the liquid is discharged from the centrifuge.
Commonly used types of centrifuges include three-legged centrifuges, plate centrifuges, horizontal screw centrifuges, disc separators, tube separators, etc. Among them, three-legged centrifuges and flat centrifuges are suitable for the synthesis of glufosinate-ammonium and purified production.
(3) Microporous filter
Microporous filter is a new type of solid-liquid separation equipment, which has the characteristics of high operating efficiency and high filtration precision. The structure of the microporous filter is to hang special polymer PE and PA microporous tubes in the vertical airtight body, and the filtrate is discharged through the microporous tubes.
In recent years, the filtration and washing processes in the production of ultrafine powders have been better applied. Zhang Youxin et al. used a microporous filter to filter and wash the ultra-fine cobalt carbonate powder with small particle size and high viscosity in production. The final washing water consumption is 4.0t/h, which can make the Na content less than 0.005%, and metal recovery The rate is above 99.7%, the content of metal cobalt in the mother liquor is 20mg/L, and the water content of the filter cake is about 20%.
(4) A new type of cylinder cone filter washing two-in-one
The "two-in-one" equipment for filtering and washing is a simplified product based on the "three-in-one" equipment for filtering, washing and drying.
Complete the two processes of filtration and washing in a closed container, mainly used in the pharmaceutical industry, solve the continuous production of flammable, explosive and toxic products, especially suitable for materials with high washing effect requirements, and can reduce the labor in the operation process Strength, reducing the loss of finished products.
Advantages
(1) The new cylinder-cone filtration and washing combo can complete the reaction, extraction, filtration, repeated filtration, washing, drying and other operations on a single machine, and directly obtain the finished product.
(2) The operation is flexible, and the operation cycle can be adjusted by adjusting the filter pressure difference, rotation speed, screw extrusion guide rail, etc., to adapt to changes in process conditions.
(3) This machine can form a thin filter cake on the surface of the filter medium, without filter cake filtration, high filtration speed per unit filtration area, and compact equipment structure.
(4) A fully enclosed system with a good operating environment, especially suitable for handling toxic, flammable, explosive dangerous products and fresh food biological products that do not allow pollution.
(5) It can be washed and filtered.
Especially when the material needs to be rinsed, it is thoroughly cleaned in a suspended state, and finally filtered to reduce the material transfer process, reduce pollution and waste, so the processed products are of high quality.
(6) It can be used for three operations of reaction, filtration and drying, and completes the functions of three unit equipment, greatly reducing equipment cost, floor space, labor intensity, energy consumption, etc.
(7) The power consumption of this machine is low, and the extruded cake has lower water content than the ordinary three-group flat type, and it is easy to operate.
The purification of the new herbicide glufosinate-ammonium is an indispensable link in the production process of the preparation of glufosinate-ammonium, and the selection of its key equipment is crucial to the performance of the material. As a new method for solid-liquid separation, refining and purification of glufosinate-ammonium, the new cylinder-cone filtration and washing combo developed and produced by Wuxi ZhangHua Machinery can effectively reduce the three wastes in the purification process of glufosinate-ammonium, prolong the service life of the equipment, and simplify the purification operation. The product purity is improved, the purification cost is reduced, and the method has a good application prospect.
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