Reduction of sintering energy by application of calcium fluoride as flux in lightweight aggregate sintering

This study sinters the mixture of CaF2 and dredged reservoir sediment into lightweight aggregate (LWA) at 1000-1100 degrees C, which is considerably lower than the temperature used by LWA manufacturing industry. The study is aimed to reduce energy demand and carbon emission, and to recycle waste. The sintering temperature is reduced approximately 200 degrees C by partial replacement of the reservoir sediment with CaF2. Furthermore, LWAs we made have relatively lower water sorption capacity and particle density than the requirement of present construction and civil engineering industries. In addition, F- leaching level from the LWAs is negligible. Using LWA as normal coarse aggregate to make lightweight concrete (LWC) meets the requirement of high-strength concrete. The LWC using our LWA is stronger than the LWCs using commercial LWAs in compressibility strength. Potentially, this study can be applied in the recycling of CaF2-containing sludges, discharged by wafer and liquid crystal display manufacturing plants, as a flux promoter for LWA manufacturing. (C) 2018 Elsevier Ltd. All rights reserved.