Abstract: Apparatus for calcining wet powdery gypsum which comprises:(A) a furnace which generates a hot gas having a temperature higher than 900.degree.

Abstract: Apparatus comprising means for dispersing comminuted limestone in a stream of hot gas and calcining it to form quicklime; a calcining chamber into which comminuted gypsum and the stream of hot gas containing the quicklime are introduced wherein the gypsum is calcined and thoroughly mixed with the quicklime; a gas-solids separator for separating the calcined gypsum and quicklime from the gas stream; and hydration means for hydrating the quicklime and gypsum whereby any phosphoric acid in the gypsum reacts with the hydrated quicklime to form insoluble calcium phosphate.

Abstract: This invention relates to an apparatus for calcining cement having a suspension preheater containing an auxiliary furnace in the preheater part, characterized in that said apparatus has an adjustable throttle positioned between a kiln and a mixing chamber where a combustion gas from the kiln and a combustion gas from the auxiliary furnace are joined and mixed with each other, said adjustable throttle comprising a quadrilateral flue where at least one of the walls is movable in order to control the amount of combustion gas from the kiln.

Abstract: A method and apparatus for thoroughly dispersing powdered material in a combustion chamber of a furnace in combination with a suspension preheater and a kiln to improve combustion efficiency. The material is introduced as a free falling stream in the upper zone of the combustion chamber and is contacted in the upper zone with recycled gases from a cooler and a second gas introduced at a higher velocity than said recycled gases, whereby the powdered material is thoroughly dispersed throughout said combustion chamber and heat exchange between the material and gases is enhanced.