Preparation and Characterization of Thermal Storage Ceramics from Iron-Containing Solid Waste.

Copper slag and red mud with high iron contents were discharged with an annual global amount of 37.7 and 175 million tons but had low utilization rates due to wide reuse difficulties. Studies on their large-scale utilization have become urgent. Thermal storage ceramic is a kind of energy storage material with high-added value and a potentially large market. In this study, a method to convert copper slag and red mud into thermal storage ceramics through a ceramic fabrication process was proposed. Four samples were prepared and characterized by XRD and SEM-EDS, as well as physical and thermal property tests. The relationships among phase composition, microstructure, and properties were further discussed. The results showed the thermal storage ceramic from copper slag had the best properties with a flexural strength of 68.02 MPa and a thermal storage density of 1238.25 J/g, both equal and nearly twice those of traditional heat storage materials like Magnesia Fire Bricks and corundum. The grain sizes of mineral phases in the prepared thermal storage ceramics have significant impacts on the performance of the material. Increasing the proportion of copper slag in thermal storage ceramics from red mud could enhance their performance. This study provides a new perspective on the low-cost preparation of thermal storage ceramics and large-scale utilization of iron-containing solid waste.