Analytical and experimental investigation of the relationship between spread and yield stress in the mini-cone test for cemented tailings backfill

The slump test is used to characterize the flow properties of mine backfill. However, the slump is not as easy to measure as spread in the condition of high or low slurry concentration. Models relating the spread length to yield stress in mini-cone test is not well developed. Rheological tests are also often used to determine the yield stress and dynamic viscosity of mine backfill materials. But the rheological test is expensive and not practical in the mine site. This paper evaluates the relationship between spread and yield stress by analytical derivation and experimental tests. Mini-cone tests and rheological tests were performed on 146 cemented tailings backfill (CTB) samples from nine Chinese mines and one Indonesian mine. A significant exponential relationship was found between the spread value and yield stress. An empirical formula between spread and yield stress was proposed and validated by the experimental results. The analytical formula is suitable for CPB with a yield stress of 115-385 Pa, and the empirical formula is suitable for CPB with a yield stress of 2-115 Pa. Using these two formulas, the yield stress can be calculated easily and directly by the spread value in engineering. (C) 2020 Elsevier Ltd. All rights reserved.