ferroslag

Ferroslag is the non-metallic byproduct produced during iron and steelmaking. It forms when molten iron combines with fluxes such as lime and silica and is separated from the molten metal in furnaces like basic oxygen furnaces and electric arc furnaces. The exact composition varies with the feed materials and process, but ferroslag typically contains calcium oxide, silicon dioxide, aluminum oxide, magnesium oxide, iron oxides, and various glassy silicate phases.

Physically, ferroslag is a dense, glassy material that can range from coarse to fine in particle size. It may contain iron-rich phases and sometimes requires processing to remove metals or reduce lumpiness. Depending on its treatment, ferroslag can be transformed into granulated slag or ground slag that is suitable for reuse in industrial applications.

Uses of ferroslag are determined by its chemical composition and local standards. Processed ferroslag can be used as a construction material, for example as a coarse aggregate in road bases or as a supplementary cementitious material in concrete. In some regions products marketed as ferroslag cement or pozzolanic cement use ferroslag components after processing. Additional applications have included refractory materials and, in certain cases, raw materials for ceramics or mineral wool, depending on the slag’s properties.

Environmental and regulatory aspects are important in ferroslag reuse. Recycling reduces steelmaking waste and can conserve natural aggregates, but leaching of trace metals and contaminants must be controlled through appropriate processing and testing to meet environmental and safety standards. Regulations and permitted uses vary by country and region. See also slag, steelmaking, and cement.