Abstract: A method of cement clinker manufacture comprises feeding a clinker feed material containing a source of calcium carbonate into a feed end of a cement kiln, the feed material is heat processed in the kiln to produce cement clinker with emission of carbon dioxide from thermal decomposition of said source of calcium carbonate and discharge of the carbon dioxide from the kiln, and cement clinker is discharged from a discharge end of the kiln; a coal ash derived from burning pulverized lignite or sub-bituminous coal is included in the feed material fed into the feed end to replace a portion of the source of calcium carbonate, and provides a source of calcium as well as other components notably silicon and aluminum, in the formation of the cement clinker, with a lowering of the emission of carbon dioxide in the kiln, per unit weight of cement clinker produced.

Abstract: A method of cement clinker manufacture comprises feeding a clinker feed material containing a source of calcium carbonate into a feed end of a cement kiln, the feed material is heat processed in the kiln to produce cement clinker with emission of carbon dioxide from thermal decomposition of said source of calcium carbonate and discharge of the carbon dioxide from the kiln, and cement clinker is discharged from a discharge end of the kiln; a coal ash derived from burning pulverized lignite or sub-bituminous coal is included in the feed material fed into the feed end to replace a portion of the source of calcium carbonate, and provides a source of calcium as well as other components notably silicon and aluminium, in the formation of the cement clinker, with a lowering of the emission of carbon dioxide in the kiln, per unit weight of cement clinker produced.

Abstract: Coal ash, which also consists of fly ash, is a very fine granular solid residue obtained as a by-product of coal combustion. The invention relates to the surprising result that a fuel can be obtained from coal ash. The process involves a pneumatic separation of the coal ash at relatively low temperatures. The coal ash is separated into at least two size fractions. The size fractions obtained by the process of this invention include at least one with lower carbon and another containing increased levels of carbon in the range of 50% by weight and a heating value in the range of 4000 to 6000 Btu/lb.