Silica fume We supply the undensitied silica fume which is a by-product during melting silicon metal or ferro silicon for long-term, silica fume, also referred to as microsilica or fumed silica, is a by-product material that is used as a pozzolan. This by-product is a result of the reduction of high-purity quartz with coal in an electric arc furnace in the manufacture of silicon or ferrosilicon Customs code: 28112200 Specifications and price: Sio2 contents >85%-92% I.L 90% min Density >600kg/m3 Packing - jumbo bags 900kg/packet or by buyerf+s request. Certificate : sgs certificate or others