Steel slag is a by-product of the steelmaking process. It is composed of various oxides oxidized in the smelting process by impurities such as silicon, manganese, phosphorus and sulfur in pig iron and salts generated by the reaction of these oxides with solvents. The mineral composition of steel slag is mainly tricalcium silicate, followed by dicalcium silicate, RO phase, dicalcium ferrite and free calcium oxide.

Raw material (less than 350mm ) will be conveyed to vibrating feeder, grate of vibrating feeder is set to 100mm, material with size less than 100mm(from vibrating feeder) will be conveyed to cone crusher, material with size larger than 100mm will be conveyed to jaw crusher for primary crushing.