Device for producing nanometer silicon dioxide through rice husk deep oxidation

Abstract

The invention discloses a device for producing nanometer silicon dioxide through rice husk temperature control complete oxidation. The device comprises an oxidation cylindrical shell, a particle selector, a group of high speed air nozzles, a material inlet and a material outlet. The upper end of the material inlet is provided with two pneumatic gate valves and is connected to a spiral conveyer. The material outlet is connected to an external cyclone separator, a filter and a high temperature induced draught fan. The high temperature-resistant oxidation cylindrical shell utilizes wear-resistant high temperature-resistant alloy steel, ceramic or silicon carbide as a lining and is provided with a heat preservation jacket at the outer part. The particle selector is installed at the upper end in the oxidation cylindrical shell, is tightly connected to the oxidation cylindrical shell through a transmission shaft and a mechanical seal and is driven through a high speed variable frequency motor. The high speed air nozzles are arranged at the lower part of the oxidation cylindrical shell, comprise odd number of nozzles and are installed at a small dip angle. The high speed air nozzles utilize high temperature high pressure compressed air. The produced silica has an amorphous nanometer structure, impurity carbon is completely oxidized and product purity is very high. The product is crushed to form very fine granules.

Description

technical field [0001] The invention relates to a temperature-controlled oxidative decarbonization device, in particular to a temperature-controlled oxidative decarbonization device for carbon-containing silicon dioxide, which is mainly suitable for the complete oxidative decarbonization of rice husk powder produced by carbonizing rice husk pyrolysis products. In the process of nano-silica. Background technique [0002] my country is a big rice producing country, with an annual output of about 200 million tons of rice, converted into about 40 million tons of rice husks. However, rice husk is not fully utilized as a by-product of rice processing, which not only wastes resources, but also brings great environmental pressure to the improvement of rural environment. In fact, rice husk contains about 15-20% amorphous silica, and the primary particle size of silica is about 50nm, and the distribution is uniform. It is a valuable renewable nano-mineral resource. Therefore, the ri...

AI Technical Summary

Problems solved by technology

However, there are many defects in this technical solution: First, when rice husk is piled up for carbonization and ashing, the heat in it is not timely and effectively exported, and the incineration temperature is still too high due to internal accumulation, reaching 700-750°C. Studies have shown that rice husk incineration When the temperature exceeds 600°C, the nanoparticles of silica have begun to agglomerate, and the nanostructure is destroyed; when the temperature exceeds 1000°C, the amorphous state of silica turns into a crystalline structure

The second is that the conical volume of the rice husk accumulation of the device cannot be too large, the production scale is limited, and the heat energy of the rice husk combustion is not effectively utilized, resulting in energy waste

Third, impurity carbon cannot be completely oxidized and removed

However, there are still many defects in this technical solution: first, the open flame burns, and the reaction time of temperature control is long, so precise temperature control cannot be achieved, and it is also easy to destroy the amorphous form of silica

Secondly, combustion produces a large amount of smoke and dust, which pollutes the environment and materials are entrained, resulting in serious losses

Furthermore, the design of the device itself determines that the rice husk cannot be completely burned, and the impurity carbon content of the final product will be very high. It is difficult and costly to produce high-purity nano-silica, which is not conducive to popularization.

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