Abstract: A method of calcining mineral components such as bituminous limestone in which heat is recovered from the calcining process and is used to liberate volatilizable substances within the mineral matter before the latter is subjected to calcination. The volatilized and pyrolytically decomposed substances form a fuel which is burned to produce the calcining gas mixture.

Abstract: A method of and an apparatus for cooling white cement clinker from a rotary kiln wherein the clinker is classified into at least two and preferably more particle-size fractions which are quenched with water with residence times staggered so as to increase as the particle size range increases. The cooling is effected to a temperature of below 1200.degree. C. but without excessively cooling the clinker so that all fractions retain sufficient sensible heat to drive off water picked up during the quenching process and resulting in completely dry clinker.

Abstract: A method of firing granular carbonate minerals, for example a cement-calcine-forming meal, in which the comminuted solids are preheated in a fluidized bed or by like entrainment in a hot gas and then subjected to decarbonation in a precalcinator before entering a rotary kiln from which the cement clinker is discharged into a cooler for heat exchange between the hot clinker and air. According to the invention, the meal is suspended in the precalcinator, which forms an upright shaft at the inlet end of the kiln, so that the particles do not pass into the kiln directly from the precalcinator but rather can be entrained by the gases in the precalcinator, separated therefrom in a cyclone and delivered to the kiln. Fuel is mixed with the kiln exhaust gases just ahead of the zone at which the meal is suspended so that the sensible heat of the exhaust gas vaporizes the fuel or gasifies the latter.