Measuring the onset of mine tailings erosion

The present study gives details of a methodology for estimating the critical shear stress for erosion of mine tailings and other naturally occurring cohesive sediments. Erosion of a cohesive sediments bed occurs when the critical shear stress is exceeded to break the interparticle bond. Experiments were conducted in a 30 cm diameter laboratory column and calibrated using laser Doppler anemometry. The results showed that the erosion pattern of mine tailings particles was similar to those of fine-grained cohesive sediments. A power-law relation of the form E = alpha[(tau - tau(cr))/tau(cr)](n) is suggested for mine tailings, where E is the erosion rate, alpha is a coefficient, tau is the shear stress, tau(cr) is the critical shear stress, and n is an exponent. The computed values of alpha, n, and tau(cr) in the power-law equation were found to be comparable to values derived from experiments in a rotating circular flume. The derived expression for rate of erosion may be incorporated in resuspension and transport models for fine mine tailings of a similar nature.