Composition and general characteristics of limestone: Limestone is one of the most widely distributed minerals in the earth's crust. According to the different components contained in the ore, lime powder, limestone can be divided siliceous limestone, clay, limestone and dolomitic limestone three. Chinese limestone rich in mineral resources, as cement, solvents and chemicals for industrial use has reached eight hundred at the limestone deposit. Origin throughout the provinces, municipalities and autonomous regions can be found in the vicinity of the industrial area of ??local materials. In the selection of raw materials or the use of lime on many grade limestone (CaCO3 calcium carbonate), and Hebei lime powder, often CaO (calcium oxide) content greater than 54%, SiO2 (silicon dioxide), S (sulfur), P (phosphorus), MgO (magnesium oxide), Fe2O3 (iron oxide), Al2O3 (aluminum oxide) and other impurities in the low active lime calcination of limestone as a raw material. Physical and chemical properties of the primary guarantee because it is to achieve active lime product should have, and this is very important.