Rheological and thixotropic properties of cemented ultrafine tailings backfill with cold-bonded lightweight aggregates

Abstract

To combine the coarse aggregates into cemented paste backfill provides a feasible method to improve workability performance. In this study, two types of cold-bonded tailings lightweight aggregates (CBTLWAs) with the discrete (uniform particle size d = 2–8 mm) and continuous (Talbot coefficient n = 0.2–0.8) gradations at different dosages (15–40 wt%) were prepared and their influence on rheological as well as thixotropic behavior of cemented ultrafine tailings backfill (CUFTB) was explored accordingly. The obtained results illuminate that CUFTB incorporating CBTLWAs exhibits behavior of Bingham fluid irrespective of particle size gradations and dosages. With the increase of CBTLWAs dosage from 15 wt% to 40 wt%, both yield stress and plastic viscosity show a continuous decrease. For a fixed CBTLWAs dosage, the minimum values of yield stress and plastic viscosity are observed when d is 2 mm and n is 0.6. As a partial replacement for tailings, the addition of CBTLWAs reduces formation of floc structures and promote more release of free water, thus enhancing flowability of CUFTB. The thixotropic performance of CUFTB is weakened with addition of CBTLWAs. As the CBTLWAs dosage increases, the slump flow exhibits a linear increase trend. An exponential model is established to quantify the relationship between yield stress and slump flow values. The findings provide a guidance for the application of CBTLWAs in mine filling and contribute significant insights into sustainable mine tailings management.