Effects of carbide slag on the performance of phosphogypsum backfill paste

Phosphogypsum backfill technology is an important way of backfill mining. However, phosphogypsum has problems such as poor water resistance and low strength. Therefore, in this study, phosphogypsum and carbide slag (CS) were mixed to form the phosphogypsum backfill (PB). The effects of the CS content on the workability, mechanical properties, and microstructure of PB were studied by means of pH value, bleeding rate, fluidity, strength, water resistance, SEM, and XRD. The results showed that the incorporation of CS significantly improved the working performance. The softening coefficient initially climbed and subsequently declined. Peak stress and MOE of PB showed a trend of rise-fall, reaching the peak when CS content was 10%. The damage evolution process of PB was revealed. The process of energy dissipation of PB during uniaxial compression showed a law of increasing and then decreasing with increasing CS dosage. The test group composed of 90% phosphogypsum and 10% CS was the best experimental scheme. These results were hoped to provide guidance for the comprehensive utilization of phosphogypsum and CS and the theoretical basis for the application of PB in backfill mining.