Vertical Slag Mill is the equipment to grind Ground Granulated Blast furnace Slag into small particles. In China, quality slag (fineness:4200-4500cm2/g) produced by vertical roller mills are being used to substitute clinker in conventional cement manufacturing as well as to partially replace OPC for ready-mixed concrete production, for which the percentage of GGBS usage is typically at 10-15% and 20-25% respectively.