Synergistic Sintering of Multi-Source Petrochemical Wastes for High-Strength Ceramsite: Process Optimization and Environmental Safety

The sustainable management of typical petrochemical hazardous wastes, such as oil sludge (OS), spent fluid catalytic cracking catalysts (SFCCs), and petrochemical-contaminated soil (PCS), poses a significant challenge. This study developed a synergistic sintering strategy that utilizes the complementary properties of these materials, with OS serving as an organic source, SFCCs and PCS providing an aluminosilicate framework, and waste glass powder (GP) acting as a fluxing agent to produce an environmentally friendly, high-strength ceramsite (OSPG-Opt). Single-factor experiments were first conducted to investigate the effects of OS content, sintering temperature, and duration. Subsequently, the Box-Behnken design was employed to optimize the process for maximizing aggregate strength. The optimal conditions were determined to be 30.5% OS content, a sintering temperature of 1142 °C, and a sintering time of 32 min. Under these conditions, the resulting ceramsite demonstrated a compressive strength of 23.12 MPa, along with a bulk density of 1012.50 kg/m³ and low water absorption of 1.61%, meeting the requirements of the Chinese standard T/CSTM 00548-2022 for structural materials. Microstructural analysis identified the presence of quartz, anorthite solid solution, hematite, and albite. The remarkable mechanical strength is attributed to an interlocking structure of anorthite solid solution within a glassy matrix, which also contributes to effective heavy metal immobilization, ensuring the excellent environmental performance of the final product.