METHOD OF ECOLOGICALLY CLEAN UNDERGROUND GASIFICATION OF COAL Russian patent published in 2009 - IPC E21B43/295 

FIELD: mining.

SUBSTANCE: method of ecologically clean underground gasification of coal consists in preparing underground gas-generator to operation and in performing gasification of coal. Also during gasification there is performed control over pressure in the underground gas-generator and correcting of hydraulic modes of blow and gas withdrawing boreholes, control over hydro-static level of underground water and over concentration of chemical impurities in underground water by means of hydro-observed and draining boreholes. Process of gasification is carried out successively in two stages - a pressurising stage at increased pressure in the underground gas-generator equal approximately to pressure of existing hydro-static column of underground water on the section of gasification and a pressurising-suction stage at minimal pressure in the underground gas-generator. Notably, at raised concentration of chemical impurities in underground water in the first stage of the gasification process in hydro-observed and/or draining boreholes the hydro-static level of underground water is raised by means of shutting-off the water withdrawing and draining boreholes, while at the second stage of the gasification process output of the water withdrawing and draining boreholes and smoke exhausts on gas withdrawing boreholes is increased. Further, underground water withdrawn with water withdrawing and draining boreholes is subject to purification from chemical impurities in a surface complex.

EFFECT: preventing ecological pollution of underground water with products of thermal decomposition of coal due to minimisation of gasification products migration from underground gas-generator.

5 cl, 2 dwg