Preparation of Lightweight and High-Strength Ceramsite from High-Silicon Lead-Zinc Tailings: A Sustainable Method for Waste Recycling

This study proposes a sustainable method to convert high-silicon lead-zinc tailings (HS-LZT) into lightweight and high-strength ceramsite, aiming to address the issues of solid waste management and resource efficiency by using HS-LZT and kaolin as the main raw materials and silicon carbide (SiC) as the pore-forming agent. A sintering process was employed to prepare lightweight, high-strength ceramsite. X-ray diffraction (XRD), X-ray fluorescence (XRF), Thermogravimetric-differential scanning calorimetry (TG-DSC), and inductively coupled plasma optical emission spectrometer (ICP-OES) were used to analyze the physical composition and physical and chemical properties of the raw materials. The influence of raw material ratios, SiC content, sintering temperature, and sintering time on ceramsite properties was investigated, and the microstructure of the optimal finished ceramsite was analyzed. The results show that under optimal preparation conditions (70% [by mass percentage] of HS-LZT, 30% [by mass percentage] of kaolin, with an addition of 0.5% [by mass percentage] of SiC, a sintering temperature of 1200 °C, and a sintering time of 20 min), the LZT ceramsite achieved a compressive strength of 11.39 MPa, a bulk density of 724 kg/m3, and a 1 h water absorption rate of 4.82%. The leaching content of Pb and Zn of the sintered ceramsite samples is far less than the limit values of hazardous components in the leachate specified in the relevant standard. This study provides a potential pathway for the reduction, recycling, and environmentally sound utilization of HS-LZT, which is in line with the sustainable development concept of “treating waste with waste.”