PROCESS FOR MANUFACTURING ULTRA LOW CONSISTENCY .ALPHA.- AND.BETA.- BLEND STUCCO

摘要

A process is disclosed for making a blend of alpha- and beta-stucco inclu ding a slurry calcination step to produce alpha calcium sulfate hemihydrate followed by a fluidized bed calcination step to produce beta calcium sulfate hemihydrate. The process starts with 50-75% gypsum-containing solids slurry , and then steam calcines the slurry in a first reactor to form partially ca lcined gypsum slurry which contains calcium sulfate dihydrate and alpha calc ium sulfate hemihydrate. The partially calcined slurry is then dewatered. Th en the filter cake is fed into a kettle to complete the calcination process by converting the calcium sulfate dihydrate of the filter cake material into beta calcium sulfate hemihydrate.