Effect of flux components of lightweight aggregate on physical properties and heavy metal solidification performance

•The influence of flux components on the physical properties of LWA is fully analyzed.•Beneficial to the composition regulation of LWA for recycling solid waste.•The mechanism of flux components on solidification of Cr was revealed.•The valence state of Cr in LWA with different Fe content was tested by XPS. The preparation of lightweight aggregate (LWA) by high-temperature sintering is a promising method for recycling solid waste safely, especially for solidifying heavy metals effectively. The main aim of this research was to systematically evaluate the effects of the flux components on LWA, including Na2O, MgO, CaO, and Fe2O3. The physical properties and chromium solidification mechanism of LWA were characterized and analyzed. The results showed that the addition of Na facilitated LWA preparation and Cr solidification, whereas Ca, Mg, and Fe were deleterious to some extent. Further analysis indicated that increasing the Fe2O3 content was not conducive to the reduction of Cr because its decomposition reaction creates an oxygen-rich environment. The results of this research could provide a meaningful guide for regulating the composition of raw materials for the production of LWA to treat industrial Cr-containing solid waste.