Abstract: A process for the selective removal or chemical modification of minerals contained in carbonaceous materials, comprising treating with an aqueous solution of a compound selected from ammonium salts, polyhydroxy alcohols, organic acids, organic complexing agents and polysaccharides. The process may be used to increase coal recovery, improve coal quality and enhance coal ash fusion characteristics.

Abstract: The invention concerns a process for the preparation of demineralized coal, comprising the steps of:(a) forming a slurry of coal particles, preferably at least 50% by weight of which particles have a maximum dimension of at least 0.5 mm, with an aqueous solution of an alkali, which solution has an alkali content of from 5 to 30% by weight, such that the slurry has an alkali solution to coal ratio on a weight basis of at least 1:1;(b) maintaining the slurry at a temperature of from 150.degree. to 300.degree. C., preferably 170.degree. C. to 230.degree. C., for a period of from 2 to 20 minutes substantially under autogenous hydrothermal pressure and rapidly cooling the slurry to a temperature of less than 100.degree. C.