Foamed ceramsite derived from oil-based drilling cutting residue and fly ash: basic properties, risk assessment, and...

Oil-based drilling cuttings residue (OBDCR) and fly ash (FA) are hazardous industrial solid wastes whose safe and cost-effective disposal remains an environmental challenge. This study addresses this issue by developing a novel approach to transform OBDCR and FA into value-added foamed ceramsite, thereby contributing to sustainable waste management and resource recovery. The primary aim was to optimize the synthesis parameters to produce a lightweight, high-strength, and environmentally stable material. Using OBDCR and FA as the main raw materials and borax as a fluxing agent, a univariate experimental design was employed to systematically investigate the effects of calcination temperature, duration, and foaming agent content on the material's properties. The ceramsite was characterized in terms of porosity, water absorption, compressive strength, acid/alkali resistance, and heavy metal leaching potential. Results demonstrated that under optimal conditions (850 °C, 1 h, 6% foaming agent, and OBDCR:FA:Borax = 35:35:30), the foamed ceramsite exhibited superior performance: 65% porosity, 14.9% water absorption, 4.02 MPa compressive strength, and acid/alkali resistance exceeding 99%. Critically, the leaching concentrations of heavy metals were significantly below the limits of Chinese national standard GB/T 5085.3, and multiple ecological risk assessment methods confirmed negligible environmental hazards. Pilot-scale experiments further validated the feasibility and economic potential of this approach. This work presents a novel, efficient, and low-risk pathway for the utilization of hazardous solid wastes, offering a practical inorganic material solution for industrial waste recycling and environmental protection.