Manufacturing of ceramic lightweight aggregates from oil-based drill cutting pyrolysis residues

In this study, high-strength ceramic lightweight aggregates were prepared from oil-based drill cutting pyrolysis residues, and their formation mechanism and expansion during sintering were examined. It was found that the Al2O3 suppressed the melting process and increased the particle strength. In particular, Al atoms penetrated the liquid phase and formed a Si-Al-O crystal structure with four ligands, which reacted with CaO and BaO to produce aluminosilicate crystals, such as BaAl2Si2O8 and CaAl2Si2O8, which increased the compressive strength. Scanning electron microscope images revealed that the glass phase also contributed toward the high strength of ceramic materials by adhering to crystal grains and forming a concrete-like structure. Energy-dispersive X-ray spectroscopy data suggested that similar to Ca atoms, Ba atoms in pyrolysis residues played a critical role in the production of aluminosilicate, while transmission electron microscopy images confirmed that different phases were not well separated as Ba and Ca were stabilized in the same crystal grains. After SiC addition and increasing the sintering temperature, the product density significantly decreased while its porosity increased.