Method used for preparing light calcium silicate boards from waste silica fume

The invention provides a method used for preparing light calcium silicate boards from waste silica fume, production cost of calcium silicate boards is reduced, and both economic benefits and social benefits are achieved. The method comprises following steps: A, silica fume collected from different ferroalloy plants is subjected to component analysis, and mixing and combination are carried out based on analysis indexes so that indexes of silica fume obtained via mixing and combination are capable of satisfying production requirements; B, full decomposition of composite fiber is realized using a pulping machine, a thickening agent is dissolved in water so as to obtain an aqueous solution, decomposed fiber and the thickening agent aqueous solution are added into pulping water, an obtained mixed material is stirred to be uniform, weighed silica fume, quartz sand, slaked lime, cement, and coal ash microsphere are added, and a slurry needed by calcium silicate board production is prepared using a mixinghollander, wherein the coal ash microsphere is obtained via pre-wetted treatment; and C, the slurry is subjected to board preparation machine moulding, pressurization, maintenance and sizing, high pressure steaming, drying, sanding, and the like so as to obtain the light calcium silicate boards.