Method for making smooth surface gypsum fiberboard panels with dilute and calcined slurry deposited on pond, sprayed and pressed

摘要

Ground gypsum and host particles of a fibrous reinforcement material and liquid are mixed to form a slurry of at least 70% by weight liquid and the gypsum is calcined by heating the slurry under pressure to form acicular calcium sulfate hemihydrate crystals. The slurry is deposited on a surface to form a pond of slurry and a fluid spray is directed at the pond to impart energy to the slurry pond surface. The pond of slurry is then dewatered to form a filter cake which is pressed to form a board and additional water is removed. The board is then dried to remove any free water. The forming system 10 typically includes head box 12, vacuum boxes 14, fluid spray apparatus 50, a wet primary press 16 and a secondary press 18.