Effect of chemical constituents of oxytetracycline mycelia residue and dredged sediments on characteristics of ultra-lightweight ceramsite

In order to solve disposal problems of hazardous solid wastes, oxytetracycline mycelia residue (OMR) and dredged heavy metal-contaminated sediments (DS) from Tai Lake were utilized as raw materials to produce ultra-lightweight ceramsite (ULC). Effects of mass ratios of organic matters/SiO 2 +Al 2 O 3 (O/SA) and MgO+Fe 2 O 3 +CaO/SiO 2 +Al 2 O 3 (MFC/SA) on characteristics of the ceramsite were investigated to optimize the ULC production process. Our results show that OMR and DS were suitable materials for ULC production, while the optimal mass ratios of O/SA and MFC/SA were 0.180–0.296 and 0.115–0.185, respectively. The addition of MFC lowered down the softening temperature and the viscosity of glass phase in ceramsite, promoting the crystallization in the glass phase. A proper MFC/SA ratio of 0.105–0.165 promoted the glass phase and increased the porosity of ceramsite. Al 2 O 3 and SiO 2 played a significant role in the formation process of crystals. However, the varying O/SA ratios only slightly impacted the variation of major crystalline phases and the viscosity of the glass phase. High MFC/SA ratios (≥0.205) decreased the crystallization of quartz, mullite and kyanite, but increased more complex crystalline phases. Additionally, the sintering process immobilized the heavy metals and could be a promising technology to control OMR pollution.