Prima macinatura e seconda cottura. Il più grande vantaggio di questa tecnica, rispetto a quello di “prima macinatura e seconda cottura”, is energy consumption reduction. Large plaster stone shall be ground into powders with diameter less than 0.2mm, which increases the specific surface when calcining, enlarges the contact area with heat medium, improves calcination heat exchange efficiency and lowers energy consumption greatly. This equipment has small bulk, large production capacity, and simple structure and is hard to destroy.