Insights into phase evolution, foaming behavior and heavy metal immobilization in the oil-based cutting pyrolysis residues based lightweight building ceramsite production: The role of SiC

To address persistent environmental pollution and achieve ecological cyclic utilization of industrial wastes, the lightweight building ceramsites were considered as a significant approach for the large-scale utilization of thermal pyrolysis oil-based drilling cutting residues (ODCPRs). Besides, the SiC foaming agent played a critical role in the performance of the ceramsite. In this work, the effects of varying SiC dosages on the physical properties, phase evolution, pore structure development, and heavy metal immobilization of the ceramsite were comprehensively examined. Additionally, the interrelationships among phase changes, pore structure, heavy metals immobilization as well as the coupled effects on the performance of the sintered ceramsite were also thoroughly elucidated. From the results, the physical properties of the ODCPRs-based ceramsite were significantly affected by the addition of SiC, demonstrating an effective foaming capability. Furthermore, a combined effect of the high-temperature reaction and the oxidation of SiC has led to abundant gas generation and increased formation of glassy phases, which effectively promoted the expansion of ODCPRs-based ceramsite during the sintering reaction. Thus, the geometry, density and the internal pore structure of the ceramsite were seriously altered, ultimately brought about notable changes in the performance of the ODCPRs-based ceramsite. Moreover, the immobilization of heavy metals was enhanced by promoting the rearrangement of the crystalline structure and facilitating the formation of a glassy phase upon SiC addition. Therefore, these findings from this work would provide a theoretical and experimental basis for the preparation and performance optimization of the oilfield-solid-waste-derived lightweight building ceramsite in applications.