Abstract: Coal, oil shale and similar carbonaceous solids are beneficiated by subjecting the solids to electromagnetic radiation having a frequency between about 0.1 MHz and about 10.sup.5 MHz in the presence of an aqueous acid solution. The electromagnetic energy enables the acid to solubilize a substantial portion of the mineral matter contained in the solids at low temperatures and pressures, thereby producing beneficiated carbonaceous solids containing relatively small amounts of inorganic constituents.

Abstract: In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by treating them with electromagnetic radiation having a frequency between about 0.10 MHz and about 10.sup.5 MHz in the presence of water or other aqueous medium. During the treatment step, the electromagnetic radiation facilitates the extraction of alkali metal constituents from the water-insoluble alkali metal compounds comprising the alkali metal residues. The resultant aqueous solution enriched in water-soluble alkali metal constituents is then separated from the particles depleted in alkali metal constituents and recycled to the gasification process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst.