Influence of rheological characteristics on the fluidization catastrophe of tailings flows

Limited by mining technology,mineral exploitation can produce large amounts of tailings.Heavy summer rainfall or seasonal freeze-thaw can lead to physical and chemical modification of tailing material in mountainous areas,resulting in fluidized tailings flow and severe disaster losses.Therefore,aiming at the problem of tailings fluidization catastrophe,this paper tried to reveal the rheological mechanism of tailings fluidization transformation by combining rheological tests and theoretical analysis.The results show that the yield stress increases with decreasing temperature,and when the density of debris flow(ρ)is more than 1.9 g/cm~3,this behavior becomes more pronounced as the density increases.The storage modulus decreases by at least two orders of magnitude at the solid-fluid transition under amplitude test sweep.Storage and loss modulus in the linear viscoelastic range and yield stress have an exponential growth relationship with sediment concentration.In addition,a stress constitutive relation and a new exponential law describing the evolution of yield stress required for solid-liquid transformation were proposed,and the relationship is further strengthened through a comprehensive analysis of existing results,which expands the evaluation application of the rheological characteristics of tailings flow.This paper provides a new insight into the rheological properties of tailing and how they occur through solid-liquid transition under different environments,which is beneficial to geological hazard prevention and the ecological remediation of the mining area.

A column study of the hydro-mechanical behavior of mature fine tailings under atmospheric drying

In this paper, the hydro-mechanical behavior and physical properties of mature fine tailings(MFT) under atmospheric drying are investigated through a column study. In the study, evaporation takes place in the development of suction in the upper parts of the column and increasing suction leads to higher strength in the tailings. After 5 days, the suction in the first lift is around 17 k Pa in the upper part of the column.When a second lift is added, the first lift initially loses strength but over a 30 days' period, the strength is recovered to its prior value and suction in the second lift reaches 500 k Pa. The vane shear strength values show a substantial increase in the strength of the MFT after 30 days under atmospheric drying and drainage. The 90% strength found in the column exceeds the threshold(5 k Pa). The hydraulic-mechanical properties of the deposited tailings are closely coupled due to several mechanisms, such as evaporation,drainage, self-consolidation, suction and crack development. The findings of this study will provide a better understanding of the placement behavior of multiple lifts of MFT and thus contribute to reclamation design standards and reduce the use of dedicated disposal areas.