The effect of particle shape on the behaviour of gold tailings

摘要

Gold tailings are (as far as can be determined) unbonded, and because of their origin contain very little clay, yet their fine fraction (the so-called 'slimes') is much more compressible than their coarse fraction (the 'sands'). The paper presents laboratory data for South African gold tailings that show this effect, and uses scanning electron microscopy to demonstrate the linkage between particle size and particle shape. Coarse particles are observed to be rotund, whilst fine particles are platy. Triaxial test results for reconstituted gold tailings are compared with similar data for Leighton Buzzard (coarse, rotund) sand containing different proportions of fine-sand sized (platy) mica. In these experiments no attempt was made to investigate the effects of different structures and fabrics. The triaxial specimens were prepared by spooning, and surface-stirred to remove fabric. Despite these limitations, a pattern of behaviour consistent with that of gold tailings was observed, suggesting that the high compressibility and other "clay-like" behaviour of slimes is a result of particle shape.