METHOD OF PRODUCTION OF BUILDING GYPSUM Russian patent published in 2003 - IPC

FIELD: production of binding gypsum materials. SUBSTANCE: proposed method includes heating gypsum to temperature of 140-190 C followed by cooling and grinding; calcium sulfate dihydrate of 0-25 mm fraction is formed as vertically oriented parallel descending layers; filtration of heat-transfer agent in each layer is performed simultaneously in straight- flow, counter-flow and crossing flow; heat-transfer agent is fed to gypsum layer at two-stage heating at temperature ranging from 250 to 700 C. At first stage, hat-transfer agent is fed to layer at temperature of 450-700 C and at second stage, heat-transfer agent is fed at temperature of 350-450 C. Ratio of gypsum layer height at first stage to that at second stage is equal to 1: 1.5. Cooling is effected by supply of air to gypsum layer which is mixed with heat-transfer agent after heating and is fed to layer of second stage. EFFECT: smoothness of heat treatment; increased productivity; reduced power and heat requirements. 4 cl, 3 dwg, 3 ex