In situ solution mining of coal

A method according to claim 4 wherein the catalyst is iron oxide.

A method of liquefying coal is situ in an underground coal seam by hydrogenation thereof comprising the steps of sequentially and repeatedly fracturing the underground strata around and in the coal seam with hydrogenated coal that is a fluid at a temperature maintained in the coal seam and settable at a temperature in the strata around the coal seam to seal the boundary of the coal seam to contain a hydrostatic pressure in the coal seam of from about 100 to about 500 atmospheres and to provide a gas and fluid-tight, overstressed cavity when the coal in the coal seam is liquefied, supplying an hydrogenating solvent for the coal to the coal seam and maintaining the hydrogenating solvent in the coal seam at a temperature of from about 300 to about 500.degree. centigrade and a pressure of from about 100 to about 500 atmospheres.

A method of liquefying coal in situ in an underground coal seam by hydrogenation thereof comprising the steps of stressing the underground strata around and in the coal seam with a settable cement to seal the boundary of the coal seam to contain a hydrostatic pressure in the coal seam of from about 100 to about 500 atmospheres, supplying an hydrogenating solvent for the coal to the coal seam, maintaining the hydrogenating solvent in the coal seam at a temperature of from about 300 to about 500.degree. centigrade and a pressure of from about 100 to about 500 atmospheres and fracturing further the underground strata around and in the coal seam with hydrogenated coal that is a fluid at a temperature maintained in the coal seam and is settable at a temperature in the strata around the coal seam to increase the stress of the underground strata.

A method of liquefying coal in situ in an underground coal seam by hydrogenation thereof comprising the steps of supplying an hydrogenating solvent for the coal to the coal seam, maintaining the hydrogenating solvent in the coal seam at a pressure below the overburden stress of the underground strata and a temperature sufficiently high and a time sufficiently long to hydrogenate a selected volume of the coal in the coal seam and fracturing the underground strata around and in the coal seam with said selected volume of hydrogenated coal, said hydrogenated coal being a fluid at a temperature maintained in the coal seam and settable at a temperature in the strata around the coal seam, thereby to seal the boundary of the coal seam to contain a hydrostatic pressure in the coal seam in excess of the overburden stress.