Metallurgical Properties of Blast Furnace Extruded Briquettes (BREX) Based on Hematite Concentrate

The metallurgical properties of blast-furnace ore and ore-coal extrusion briquettes (BREX) based on hematite iron ore concentrate are studied. With respect to values of hot strength brex occupy an intermediate position between sinter and pellets. The reduction capacity for brex is significantly reduced with simultaneous addition of flux and solid fuel, which may be associated with a reduction in porosity (due to clogging of pores and the formation of a surface metal crust). Brex softening temperature range is largely dependent on composition and varies widely (130–330°C). The temperature range for onset of softening for all samples tested is 860–960°C. Prior softening of brex compared with sinter and pellets occurs due to a reduction in brex mechanical strength after loss of cement bonding properties (700–750°C) caused by loss of chemically bonded water and decomposition in the solid state of ferroakermanite (cement clinker component) at 775°C. It is necessary to take into account the difference in temperatures for the onset of softening of brex, sinter and pellets when selecting a multicomponent blast furnace charge. This makes it possible to avoid an increase in temperature in the cohesion zone and to reduce the zone for indirect reduction of oxides in the process of combined smelting with pellets and sinter. The data obtained make it possible to consider hematite ore based brex as a suitable blast furnace charge component.