SU1472444A1 - Method of producing finely particulate silicon dioxide - Google Patents

Abstract

The invention relates to the preparation of pyrogenic silicon dioxide, used as a filler in polymeric materials, a thickening agent for liquid phase compositions, in the preparation of adsorbents and catalyst carriers, and reduces the energy intensity of the process. The products of the hydrolysis reaction of silicon halide in an air-hydrogen flame after exiting the reactor with a temperature of 450 ° C and above enter the first separation stage, where, at a temperature of at least 400 ° C, the main part of SIO _{2 is} captured, which does not require further purification. The remaining part of SIO ₂ together with the gaseous products of the hydrolysis reaction enters the stage of cooling and coagulation of SIO ₂ particles. The temperature of the aerosol mixture after the cooling and coagulation step is 120-175 ° C. The final separation of the aerosol mixture is carried out in a second separation stage in cyclones at a temperature of 100-150 ° C. The silica caught in the second separation stage is purified from adsorbed chlorine and hydrogen chloride impurities at elevated temperatures (400-700 ° C), and gaseous products enter the hydrogen chloride and chlorine absorption stage. 1 tab.

Description

445 ° C. The mixture then enters the cyclone in the first separation stage. The temperature of the mixture in the cyclone. As a result, in the first stage of separation, 29.9 kg / h (80.1% of the total amount) of highly dispersed silicon dioxide, which meets the requirements of GOST 14922-77 and does not require additional costs for the removal of adsorbed impurities HC1 and Cl ( j.

The gaseous products of the hydrolysis reaction and silicon dioxide not captured in the cyclone pass through the coagulation and cooling phase of the mixture to 105 ° C. At this temperature, the second stage of decomposition is carried out in a cyclone. As a result, 7.5 kg / h of 19.9% of the total amount of highly dispersed silicon dioxide is obtained, which is further subjected to additional purification from adsorbed impurities of hydrogen chloride and chlorine by heat treatment at 500 ° C.

Gaseous products of hydrolysis (nitrogen, oxygen, hydrogen chloride, chlorine, water vapor) are fed to the - stage

adsorption of hydrogen chloride and chlorine,

The specific energy consumption is 3.68 kWh / kg Si02, including the energy consumption for heat treatment — 0.25 kWh / kg Bi02.

Claims (1)

The table shows the conditions for the implementation of the proposed and well-known methods for producing highly dispersed silicon dioxide and the value of specific energy consumption according to the examples given. Invention Formula The method of obtaining highly dispersed silicon dioxide, including burning a mixture containing silicon tetrachloride vapors, hydrogen and oxygen-containing gases, in a flare, cooling, separating the resulting silicon dioxide in a cyclone p: Pu 100-15Q JC .. and purifying it, distinguishing so that, in order to reduce energy consumption, to the cooling stage, the formed silicon dioxide is preliminarily separated at a temperature of at least. The conditions for the implementation and characteristics of the production of highly dispersed silicon dioxide, proposed in the Service. Offering- wow J100 3085350 100 28.7 84.3 5.4 13.7 ", 15 2 / PO 3490400 105 29.9 80.1 7.5 19.53.68 150 45 250 75 250 72 120 500 115 39.2 76.9 11.8 23,13,26 210 700 150 59.6 70.6 24.9 29.43.19 220 150 84, 6 100.0 4.03 13.7 ", 15 19.53,68 23,13,26 29,43,19 100.0 4.03 Required dopolv. Thermal Piping Vetka after the separation stage B of the stage requires thermal treatment 1) after stage I of the pai division. Also P The first stage of sleep is not available.