Method for preparing ultrafine high-purity SiO2 from volcanic ash

Abstract

The invention discloses a method for preparing ultrafine high-purity SiO2 from volcanic ash. The method comprises the following steps of: A, taking 100 weight parts of the volcanic ash of which the SiO2 content by weight is more than or equal to 50 percent, crushing the volcanic ash to ensure that the particle size is less than or equal to 1 mm; B, adding and dispersing the volcanic ash into acid solution of which the temperature is between 40 and 95 DEG C, stirring for 10 to 180 minutes, and filtering and washing; and C, transferring the volcanic ash processed in the step B into 300 weight parts of water of which the temperature is between 35 and 100 DEG C, adding NaOH or KOH of which the equivalent weight of the SiO2 is equal to that of the SiO2 in the volcanic ash with stirring to form a uniform sol system, then adding 0.5 to 5 weight parts of hydrophobic substances into the uniform sol system, introducing 500 to 1,500 weight parts of organic solvent which is immiscible with water, stirring at a high speed to form a micro-emulsion system, dropping an acidic substance to generate a deposit, filtering to obtain the deposit, and washing and drying the deposit to obtain the ultrafine high-purity SiO2. The method has the advantages of low raw material cost, simple preparation process and easy industrialization; and the prepared ultrafine high-purity SiO2 has uniform particle size distribution and high purity, and can be used as a functional filling material directly.

Description

Technical field: [0001] The invention relates to an ultrafine high-purity SiO 2 method of preparation. Background technique: [0002] Ultra-fine high-purity SiO 2 As a new type of functional material, due to its superior properties such as high dielectric, high heat resistance, high moisture resistance, high filling content, low expansion, low stress, low impurity, and low friction coefficient, it has great potential in many fields such as electronics, electrical appliances, and chemical industry. It has broad application prospects and is an ideal high-quality functional filler for electronics, electrical appliances, and chemical products. Since Stober invented the alkoxide hydrolysis process to prepare ultra-fine high-purity SiO 2 Since then, methods such as spray drying and template self-assembly have emerged one after another, and ultrafine high-purity SiO 2 The preparation method has been in continuous improvement and updating. Currently, ultrafine high-purity SiO ...

AI Technical Summary

Problems solved by technology

At present, ultrafine high-purity SiO 2 There are three main types of preparation methods: 1. The gas phase method using halosilane as raw material. The product has a narrow primary particle size distribution and good dispersion. 2 The main method, but the cost of the raw material halosilane is high, and the reaction is carried out in a high-temperature gasification environment, which has the disadvantages of complex process, strict requirements on equipment, easy loss of product, and low yield.

Two, the precipitation method using water glass as the basic raw material, although the method has a wide range of raw materials and relatively low prices, it directly prepares silica by water glass and alkali precipitation reaction, and the purity of water glass cannot be guaranteed, resulting in the prepared SiO 2 The purity is not high, because it is precipitated in an ordinary solution, and the length of the precipitation process varies, resulting in uneven particle size and difficult shape control

Its disadvantage is that the raw material cost of metal alkoxides such as orthoethyl silicate (TEOS) is high, and the supercritical drying process needs to use an autoclave, the yield is low, and it is not easy to industrialize

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