MgO: 65%--85% CaO : 3%max SiO2 : 5%max LOI: 5%max Size(mm) : 10-40mm 30-80mm The caustic calcined magnesite is made from calcined magnesite powder through Mixing, pressing spheroid. It is used for converter steel making, through the splashing cross to protect the furnace, which can raise the furnace life. 25kg/bag.