Preparation of high-strength bricks by synergistic densification treatment of phosphogypsum and calcium carbide slag

Abstract

Phosphogypsum(PG) and calcium carbide slag(CCS) are quintessential bulk solid wastes in the chemical and energy industries. Characterized by their substantial production volumes, low resource utilization rates, and significant environmental pollution risks, these waste streams necessitate an expansion in their utilization horizons. To improve the utilization rate of PG and CCS, the densification technology was put forward to produce high-strength densified bricks. After 5 days of natural curing, the densification pressure is 300 MPa, the densified bricks containing 10 % PG and 90 % CCS demonstrated optimal mechanical and waterproof performance. The compressive strength, flexural strength, water absorption and softening coefficient of the densified bricks were approximately 105 MPa, 4 MPa, 3.2 % and 0.99, respectively. SiO₂, Al₂O₃ and Ca^2 + in the solid waste contribute to the production of cementitious substances (C-S-H), which contribute to the compressive strength and heavy metals stabilization of the densified bricks. This simple process has the potential to economically and efficiently co-process solid waste and solve its environmental problems. At the same time, it can broaden the channels for solid waste resource utilization, and the high-performance bricks prepared by densification can be used for other special functional purposes, improving their economic value and facilitating their large-scale promotion and application.