New method for preparing silicon dioxide by utilizing rice hull ash

Abstract

The invention discloses a new method for preparing silicon dioxide by utilizing rice hull ash, comprising the following steps: neutralizing and dissolving the soluble impurities in the rice hull ash by utilizing a sulfuric acid solution; adding an ammonium fluoride solution in proportion; heating and dissolving to generate ammonium fluosilicate and discharge ammonia; modulating the concentration of the ammonia water to be 10-30wt% by the ammonia generated in the water recovering reaction; placing into a seal stillpot; regulating the temperature to be 50-90 DEG C; adding the ammonium fluosilicate solution into the ammonia water in proportion; separating out the sedimentation; ageing for 0.5-3h; filtering and performing solid-liquid separation; returning the filter liquor to a silicon dissolving procedure for recycling after the filter liquor concentration is adjusted; and washing and drying the filter cakes to obtain the silicon dioxide. The method of the invention takes the regenerated resource rice hull ash as a silicon source, and adopts constant-voltage low-temperature liquid phase dissolving silicon; and the reactant ammonium fluoride and the by-product ammonia can be recycled, which not only saves the energy consumption and lowers the cost, but also has no other by-product generation and no greenhouse gas emission, thus belonging to a low-carbon green new process.

Description

technical field [0001] The invention relates to a new method for preparing silicon dioxide from rice husk ash, in particular to a new method for using rice husk ash as a silicon source and ammonium fluoride as a solvent to prepare silicon dioxide and to recycle the solvent ammonium fluoride and by-product ammonia gas . Background technique [0002] 1. The use of biomass resources to produce silica is the trend of using renewable plant resources as raw materials [0003] At present, the world's energy and resource crisis makes the development and utilization of renewable resources a hot spot. Plant / crop-based renewable resources are the trend of research and utilization at home and abroad, especially in developed countries. It will become a supplement and substitute for non-renewable resources in the future, and change the current dependence on dwindling non-renewable resources. The entry of renewable resources into the raw material market has become an important part of th...

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Problems solved by technology

[0009] The above methods have problems such as difficulty in dissolving silicon with silica sand as raw material, high temperature reaction, high energy consumption, and limited source of raw materials with fluorosilicic acid or ammonium fluorosilicate as raw material.

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