Industrial Experiment of Goaf Filling Using the Filling Materials Based on Hemihydrate Phosphogypsum

The surface stockpiling of phosphogypsum not only occupies a large amount of land, but also seriously harms the surrounding ecological environment. The preparation of phosphogypsum into filling materials for mine filling can not only maintain the stability of surrounding rock, reduce surface subsidence, enhance the recovery of resources, but it can also completely solve the problem of phosphogypsum stockpiling. Under certain activation conditions, hemihydrate phosphogypsum has a strong cementing property. It is an important way to reduce the filling cost by using hemihydrate phosphogypsum instead of cement as a cementing material. Through laboratory experiments, the filling materials based on hemihydrate phosphogypsum were developed. In order to further verify its feasibility in practical filling engineering, the industrial experiment of goaf filling was carried out in a phosphorus mine. The results show that the filling system was simple, reliable, and easy to operate and manage. The strength of the filling body basically reached the expected strength target of 2.5 MPa in 3 days. The consolidation speed of the filling materials was faster, which is beneficial to the safe underground construction of the mine. The results of the industrial experiment of goaf filling indicate that the filling materials based on hemihydrate phosphogypsum are suitable for mine filling engineering practice, the work amount is small, and the filling cost is low.