Effects of different factors on the fluidity, strength and microstructure of superfine tailings cemented paste backfill

To achieve efficient utilization of superfine tailings, a series of experiments were carried out to investigate the effects of different factors on the fluidity, strength and microstructure of the superfine tailing cemented paste backfill (SCPB). Firstly, the effects of cyclone feed pressure and sinker diameter on the concentration and yield of superfine tailings were explored and the settling characteristics of superfine tailings investigated, respectively. Then, the SCPB was investigated by uniaxial compressive strength tests, slump and rheological tests and scanning electron microscopy. The results show that the diameter of the sand settling port and the feed pressure significantly affect the bottom flow yield and concentration of tailings. The dosage of flocculant has a greater effect on the settling rate of tailings, and a less significant effect on the final concentration. The greater the mass concentration, the poorer the flowability of the slurry, which becomes significantly worse when the mass concentration is above 72%. Curing temperature, curing time and mix proportion will all affect the strength of SCPB. The slow hydration of the filler at low temperatures results in low hydration products, a loose structure and a high number of fissures, which is the underlying cause of the reduction of filler strength.