Influencing parameters on the sintering process of steel slag-based ceramics for high-temperature thermal energy storage

Abstract

This paper presents an innovative approach of utilizing electric arc furnace (EAF) slags in value-added applications, particularly as storage media for high-temperature thermal energy storage (TES) systems, applied to next- generation of central receiver concentrated solar power (CSP) plants. EAF slag is a solid industrial waste produced in large quantities in metallurgy worldwide and commonly sent to dump sites. Due to steel slag's chemical composition of metal and non-metal oxides, advanced ceramic bodies can be prepared using thermally treated EAF slag powder. The crystallographic stability of oxidized EAF slag powder was confirmed by XRD analysis that revealed the absence of any crystal phase transformation at elevated temperatures up to 1200 °C. Advanced ceramic entirely recycled from locally UAE produced EAF slag was prepared following the method of cold compaction of ceramic powder. For sensible heat TES materials, a high density is desired to maximize the storage capacity. Therefore, the final product bulk density was examined by studying the influence of parameters such as (i) the applied compaction pressure, (ii) the firing temperature, (iii) the binder weight percentage, and (iv) the firing time. Findings showed that a compaction pressure of 186 MPa resulted in relatively dense green ceramic bodies. The firing of these bodies at 1200 °C with a dwell time of 3 hours resulted in ceramic products with a bulk density in the range of 2500 kg/m3 that could be potentially used as TES media.