Abstract: A method of mining a seam of rigid hydrocarbonaceous containing mineral such as oil shale or coal whereby essentially complete recovery of the mineral deposit is possible. This method comprises the steps of apportioning the seam into one or more working horizons and extracting from about 15 to about 85 percent of the mineral in a horizon using a room and pillar mining technique. The void areas resulting from the above mining operation are then filled with concrete, which is formed from cement made from spent residue and aggregate comprised of additional spent material. After the void areas are filled the remaining mineral is removed and additional concrete is deposited. Subsequently, an adjacent horizon, either above or below the initial horizon, is excavated by repeating the above steps until essentially all of the mineral deposit is recovered.

Abstract: Disclosed is a manufacturing process for converting coal ash slag from a slagging coal gasifier into a marketable cement product having the characteristics and qualities of portland cement. This process comprises the steps of transferring molten slag from a slagging coal gasifier to a melt chamber and reacting it with a mineral containing lime, for example: calcium oxide, calcium hydroxide or calcium carbonate, to form a homogeneous cement product. This cement product is then transferred to a quench chamber where it is allowed to cool and solidify in the form of clinkers, which are later reduced to powder form.This process also provides an efficient means to conserve energy when producing a portland cement and provides an effective and economical way to dispose of a waste product while increasing the cost efficiency of a slagging coal gasifier.