METHOD FOR THE UNDERGROUND GASIFICATION OF COAL OR BROWNCOAL

摘要

ABSTRACT OF THE DISCLOSUREA method for the underground gasification of coal or browncoal, usingtwo boreholes extending through a coal layer with the slope of saidlayer, for supplying oxygen to a combustion and gasification front insaid layer and discharging combustion gases respectively. a fillermaterial being intermittently supplied through one of said boreholesfor filling the cavity produced by burning away the coal layer.According to the invention, said filling is started at a moment beforethe combustion front has reached the discharge borehole, and in partic-ular before the overlaying formations will collapse to such a degreethat an inadmissible subsidence at the ground level would develop.Thereafter the combustion and gasification is restarted in the sameor the opposite sense as may be required for adjusting the orientationof the gasification front in the desired direction.