Influence of Particle Size Composition of Tailings on Rheological Characteristics and Strength of Cemented Tailings Backfill
To investigate the correlation between the particle size distribution of tailings and the rheological properties and strength of cemented tailings backfill(CTB),five different types of CTBs were artificially prepared using full tailings,cyclone overflow,and underflow tailings.Rheological and strength tests were conducted on the CTBs,and changes in the internal pore structure of the tailings backfill were analyzed using mercury intrusion methods(MIP).The impact of the particle size distribution of tailings on the rheological properties,strength,and microstructural characteristics of CTBs were assessed.The findings indicate that an increase in fine tailings content by-38 μm results in higher rheological parameters(yield stress and plastic viscosity)of fresh CTBs,with a greater increase observed at higher fine tailings content levels.The variation in particle size distribution of tailings leads to noticeable differences in the thickness of water film of solid particles in the backfilling slurry.Specifically,an initial increase followed by a subsequent decrease in water film thickness is observed with increasing fine tailings content.The initial yield stress and plastic viscosity of backfilling slurry are influenced by the water film thickness and specific surface area of solid particles.An exponential relationship is observed between the initial yield stress and plastic viscosity of CTB when the fine tailings content exceeds 44.37%.The strength of CTB initially increases and then decreases as the fine tailings content increases.The fine tailings content of 44.37%represents the optimal particle size distribution of tailings.In this condition,the compactness of the skeleton structure of the CTB formed by the accumulation of tailings is at its maximum,resulting in the lowest values for total porosity,average pore size,and the percentage of harmful pores larger than 0.2 μm.
particle size composition of tailingscemented tailings backfillrheological characteristicswater film thicknessstrengthpore structure
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