Research on the development and performance test of phosphogypsum filling materials for mines

In order to study the feasibility at preparing mine filling materials with solid waste phosphogypsum, the filling material was prepared by adding calcium carbide slag and phosphogypsum slag, respectively, as aggregate. The single-factor experiment and orthogonal experiments were conducted to explore the effects of calcium carbide mass fraction, slag mass fraction, material mass fraction and drying temperature on the compressive strength of filling materials. The micromorphology characteristics of these samples was analyzed by SEM as well. The results show that when the mass fraction of phosphogypsum, calcium carbide and slag is 65%, 5% and 30%, respectively, the strength and initial fluidity of the filling materials with the mass fraction of 65% is within the filling requirements. The strength of filling material peaked at 130 ℃ for 8 hours. Calcium carbide slag stimulates the activity of slag. Phosphogypsum and slag form needle-like ettringite, calcium aluminate hydrate gel and calcium silicate hydrate gel, both of which enhances the strength of the filling materials.