Rheological behavior of ultrafine-tailings cemented paste backfill in high-temperature mining conditions

Abstract

The ultrafine-tailings cemented paste backfill (UCPB) exhibits special rheological characteristics in the high-temperature underground mining environment, which has an important influence on the stability of pipeline transportation. This study examines the time- and temperature-dependent rheological behavior of UCPB that the d(av) of tailing is 9.41 µm, and the effects of high temperature, solid content, cement content, and binder type on rheological behavior. It is found that the UCPB is yield plastic fluid with significant time-dependent characteristics under high-temperature. The UCPB is a positive thixotropic fluid that the shear stress and apparent viscosity decrease rapidly and then keep stable under a constant shear rate, and the falling curve is lower than the rising curve in the thixotropic loops. Increasing temperature causes a significant decrease in yield stress, apparent viscosity, and thixotropy. The rheological model of UCPB changes with the change of solid content, and shear-thickening occurred after the rheological curve stabilizes for solids content at 57 wt% and 54 wt%. Fly ash can effectively improve the liquidity of UCPB and reduce thixotropic behavior, due to its lubrication and water reducing effects. The hysteresis loop is not suitable as a means of quantitative analysis of thixotropy.