Ceramics-Silikáty

Addressing the environmental pollution caused by the large-scale accumulation of magnesium-containing solid waste and the limitations imposed on its resource exploitation due to the availability of free magnesium, this study proposes and verifies a method that utilises steel slag and ferrochrome slag in a self-responsive, high-temperature environment of fire-flooding oil recovery, combined with a CO₂-rich hydrothermal environment. Through a coupling mechanism of "high-temperature reconstruction-carbonation and hydrothermal activation," magnesium-containing calcium carbonate, C-S-H, and M-S-H phases are generated and interwoven, with a highly stable magnesium-aluminium spinel phase filling the structure to construct a dense multiphase composite. This structure has a "self-healing" capacity to seal microcracks by expansion and achieves a high compressive strength of about 80 MPa in just 72 hours. This work transforms bulk solid waste into high-magnesium oil well cement with adaptive sealing, self-reinforcing, and carbon sequestration functions, providing a green and safe approach to heavy oil thermal recovery that combines resources and environmental benefits.