Investigation on the fabrication of lightweight aggregate with acid-leaching tailings of vanadium-bearing stone coal minerals and red mud

Abstract Proper treatment of acid-leaching tailings (ALTs) of vanadium-bearing stone coal minerals is of great urgency. One approach is adding it into the raw materials during the preparation of lightweight aggregate (LWA). But clay is always needed. In this paper, another solid waste, red mud, was mixed with ALTs as a source of flux components instead of clay. Evaluation of the physical characteristics, morphological structures, as well as crystal phases during the sintering process were investigated. When their mixtures with a proper ratio were sintered at 1080 °C, a glassy phase with certain viscosity was formed, and the gases generated simultaneously were encapsulated by the melt. Finally, LWA with a one-hour water absorption as low as 1.46%, a bulk density as low as 728.76 kg·m-3 and a compressive strength as high as 10.77 MPa was fabricated.