Abstract: Method and apparatus to recover energy from waste by means of combustion of such waste in industrial furnaces, particularly of the rotary type, that has an external calciner, feeding such waste into the tertiary air duct of the calciner and burning the waste inside the duct itself, to efficiently make use of the energy produced by such combustion, as a contribution of the total cost of fuel necessary to operate the industrial furnace. The method and apparatus permit the elimination of hazardous wastes that are efficiently disassociated when burned sufficiently to produce effluents that are typically non-toxic, producing greatly reduced or even no atmospheric pollution nor environmental damage.

Abstract: A method of manufacturing cements based on calcium sulfoaluminate by forming a clinker through calcining a selection of typical cement precursor raw materials to temperatures of more than 1200.degree. C. in an industrial kiln, preferably with a preheater (typically of the cascading cyclone type) and precalciner, selected in such a manner that the clinker thus produced has a high content of calcium sulfoaluminate, tricalcium silicate and dicalcium silicate with no other calcium aluminates and, preferably during or prior to the grinding thereof, adding to the clinker thus produced (with the above recited basic components), effective amounts of calcium oxide or hydroxide and calcium sulfate, in order to activate said clinker. Upon said grinding, a temperature of about 100 to 125.degree. C.