FIELD: chemistry.
SUBSTANCE: invention can be used in chemical industry. The method involves successive acid washing of rice husks, washing with water, drying, pyrolysis of the rice husks with air deficiency at temperature of 200-500°C, burning the pyrolysis carbon residue at temperature of 500-750°C and unloading the product. The pyrolysis carbon residue is burnt in two steps - a first step for preliminary burning in a mixture with an inert substance to residual carbon content in the ash of not more than 10%, and then a second step for burning the residual carbon in a counterflow reactor in an air current. At the second step of burning the carbon residue, air is fed into the reactor into the unloading zone, and gaseous combustion products are removed from the feeding zone while maintaining temperature of 500-750°C in the middle zone of the reactor.
EFFECT: invention enables to obtain amorphous silicon dioxide from rice husks having purity of up to 99,99% and specific surface area of at least 300 m2/g in a continuous, wasteless, energy-saving and ecologically clean process with simultaneous recycling of pyrolysis products and products of incomplete combustion of husks.
11 cl, 1 dwg
