Municipal solid waste incineration fly ash (MSWIFA) is the residue from burning municipal solid waste. It contains high levels of heavy metals and, if untreated, may cause serious harm to ecosystems and public health. This study explores the use of Basic Magnesium Sulfate Cement (BMSC) to solidify MSWIFA and promote solid waste utilization. Different MSWIFA dosages were tested for their effects on the compressive strength and leaching toxicity of BMSC. X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) were used to elucidate phase evolution and microstructural characteristics. The results show that when the MSWIFA content increased from 0% to 15%, the 28-day compressive strength decreased significantly from 68.96 MPa to 40.69 MPa, a reduction of 41.0%. The 28-day compressive strength exhibited a declining trend with the increase of MSWIFA content, dropping from 68.96 MPa to 40.69 MPa as the content rose from 0% to 15%. However, BMSC exhibits excellent heavy metal immobilization performance: the leaching concentrations of Zn 2+ , Cr 2+ , and Pb 2+ dropped significantly below the standard limit. The main hydration products in the MSWIFA-BMSC material are the 5Mg(OH) 2 ·MgSO 4 ·7H 2 O (5·1·7 phase) and Mg(OH) 2 . As more MSWIFA was added, the diffraction peak intensity related to these crystals gradually weakened, although the types of phases did not change. MSWIFA with a dosage of 15% also reduced the total porosity of BMSC from 20.05% to 8.56%, while the harmless pores (less than 20 nm) decreased from 39.73% to 24.19%, indicating an improvement in the material’s microstructure. These findings demonstrate that BMSC can safely treat MSWIFA, offering a practical method for recycling this hazardous waste.
Luo et al. (Wed,) studied this question.