SU681609A1 - Method for crystallizing low-melting pesticides - Google Patents

Abstract

A METHOD OF CRYSTALLIZATION. LOWLY MELTING PESTICINES FROM MELTS by feeding the melt in a dispersed state into the flow of moving crystallized particles, characterized in that, in order to carry out the crystallization process of the pesticides, the low crystallization rate of the finished product due to the crystallization process has increased and the quality of the finished product increased due to the crystallization of the pesticides. the melt is fed to the stream (particles moving at a speed of 3-11 m / s.2. Method POP.1, characterized in that a pesticide is used as particles, or an iyert filler s, or mixtures thereof.

Description

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about 1 The invention relates to a method for the crystallization of low-melting pesticides with a low linear rate of crystallization from melts, for example chlorophos, isophene, benzophosphate, vinyl phosphate. A method of crystallization is now known, for example, chlorophos on roller molds, during which chlorophos is obtained in the form of flakes of various shapes. The main disadvantage of this method is the low productivity (10). In addition, a complex two-stage grinding system in an inert gas stream, during which a large amount of dust particles is formed, is required to prepare a flaky chlorophos formulation. Therefore, for toxic pesticides, it is required to organize a complex dust collection system and provide it with anti-spraying and neutralizing equipment. There is a method of crystallization of substances from melts of high-melting products, such as urea using a fluidized bed and blowing cold air. According to this method, the melt is fed by a spraying device directly into the fluidized bed of the finished granules. This method is difficult to granulate chlorophos and other pesticides that have low linear crystallization rates. A feature of the melts of chlorophos, isophene, benzophosphate, and vinyl phosphate is their very low linear crystallization rates and low melting points. Low linear crystallization rates make it difficult to carry out the crystallization process by known methods. During the crystallization of such pesticides in the first and second critical velocity range of 0.7–2 m / s, sticking and agglomeration of particles occur, which ultimately leads to undesirable phenomena, such as channeling and the formation of stagnant zones, deterioration of heat transfer, fluid bed heterogeneity . All this creates significant difficulties in the organization of the hydrodynamic regime. A gradual increase in the speed of the waiting agent to the second critical 2 causes a significant decrease in the heat transfer coefficient from the heat transfer surfaces of the apattate. The aim of the invention is to provide the possibility of crystallization of pesticides having a low linear crystallization rate and improving the quality of the finished product. In order to carry out the process according to the inventive method, the pesticide melt is continuously supplied by a spraying device at a certain speed into the apparatus onto a layer of particles moving at a speed of 3-11 m / s, which is created by the rotating device. The particle layer consists of an inert filler or a pre-crystallized pesticide or mixture thereof. The temperature of the bed is maintained in an interval that provides the maximum linear crystallization rate. The crystallization temperature and particle velocity are provided by a rotating mechanical device with an unfolded heat transfer surface, cooling of which is carried out by any suitable refrigerant. The proposed method has a simple technological design, the crystallization process is carried out in one apparatus, and due to the absence of entrainment of dust and explosive particles, complicated additional systems for collecting dust, cooling and neutralizing fluidizing agents and exhaust gases are not required. It should be particularly noted that the implementation of the proposed method provides a very high quality of the crystallized products, which are obtained in the form of homogeneous microgranules without the inclusion of agglomerated large cohesive particles. Products arrive immediately after crystallization on the packaging and are ready for use. An important advantage of the proposed method is to provide excellent sanitary conditions, which is very important when working with toxic organophosphorus pesticides, as well as safety conditions due to the absence of the danger of explosions. The proposed method also makes it possible to crystallize mixtures of low melting pesticides and, thus, to produce combined necTHijjifli with a wide spectrum of action.

Below are examples illustrating, but not limiting the use of the proposed method.

Example 1. In a 7 liter apparatus with a cooled stirring device and a jacket, 0.75 kg / h of aerosil and 7 kg / h of molten chlorophos are continuously fed to the bed of filler and crystallized chlorophos, which move at a speed of 3 m / s.

The heat of crystallization is completely removed through the heat transfer surfaces of the mixing device and the jacket of the apparatus, cooled with water at a temperature of 10-20 ° C. The temperature in the layer of particles is maintained at 30-40 ° C, while the melt of chlorophos has a maximum linear crystallization rate.

The obtained microgranular chlorophos and the form of round granules of the following composition:

less

0.93 kg

6.2 kg

0.62 kg

The ash fraction is completely absent.

Example 2: A 7-liter apparatus with a jacket and a mixing device on the sublayer of kaolin and isophene particles moving; at a speed of 9-11 m / s, 3 kg / h of isophene melt and 2.6 kg / h of cascina are supplied. The cooling water temperature at which iofen has a maximum crystallization rate, 10 C. The temperature in the layer is maintained through the heat transfer surfaces of the mixing device and the jacket of the apparatus. Capacity is 5.6 kg / h. The product had a crushing particle size distribution: particles with a diameter of 0.5-1 mm4.87 kg

1-2 mm 0.56 kg

2-3 mm0.17 kg

Claims (2)

METHOD OF CRYSTALLIZATION. LOW-MELTING PESTICIDES FROM MELTS by feeding the melt in a dispersed state to a stream of moving crystallized particles, characterized in that, with the aim of crystallizing pesticides having a low linear crystallization rate and improving the quality of the finished product by eliminating particle agglomeration, the melt is fed into the flow of particles moving at a speed of 3-11 m / s. 2. The method according to claim 1, characterized in that the particles used are a pesticide or an excipient filler, or mixtures thereof. 1 681609