Eco-friendly rock fracturing: Enhancing SREMA with calcium sulfate for sustainable mineral recovery

The study investigates the impact of calcium sulfate (CaSO 4 ) on the performance of Slow-Releasing Energy Material Agents (SREMAs) for in-situ mineral recovery (IMR). Comprehensive experimental analyses were conducted, including expansive pressure measurement, isothermal calorimetry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Results revealed that incorporating 1% CaSO 4 into SREMA formulations optimally enhances portlandite and ettringite formation, achieving a 15.3% increase in expansive pressure (28.67 MPa) compared to the control mix. Rheological tests indicated improved workability and cohesiveness at this concentration, balancing flowability and washout resistance in water-saturated conditions. Excessive CaSO 4 (>1%) reduced performance by disrupting hydration dynamics and forming secondary phases. The findings underscore the synergistic role of CaSO 4 in promoting hydration efficiency and volumetric expansion, which could have implications for improving the performance of SREMAs in IMR applications. Future research is recommended to further optimize the system to increase the expansive pressure generation potential in SREMA through additive enhancements and nanoparticle integration for deep subterranean applications.