Development of extruded and fired bricks with steel industry byproduct towards circular economy

In the present research, the development of building bricks is examined, using steel industry electric arc furnace dust (EAFD) as admixture into standard clayey raw materials typically used by ceramic industries, and employing a pilot-plant simulation of industrial processes for red brick manufacturing,. The recycling of solid residues, which are derived in massive quantities from steel production plants, as alternative raw materials towards circular economy, is of increasing importance. In particular, steel dust recovered from EAF gas treatment, contains several oxides and, thus, can be considered as secondary material for substituting clays in traditional brick manufacturing. Possible economic benefits for the energy intensive industrial ceramic sector from energy savings upon firing along with a high potential for environmentally safe management of steel dust should be emphasized. For that purpose, various clay/EAFD mixtures were prepared and mixed with water to form a plastic mass for brick specimen shaping by extrusion. The green specimens were dried, and then fired at different peak temperatures (850, 950 and 1050 °C) in a controlled laboratory chamber furnace for sintering and consolidation. The effect of the by-product content (%) and of the firing temperature on brick shrinkage, bulk density, water absorption capability, mechanical strength and thermal conductivity was investigated. According to the results, the development of extruded and fired bricks with up to 15 wt% recycled steel industry byproduct is feasible without significant variations in their technological properties.