Polymer-modified tailings deposition – ongoing testing and potential storage efficiency opportunities

Abstract

After thickening most mineral tailings are transported as slurry to a designated storage area, usually a slimes dam, tailings pond or impoundment area. In some cases tailings are used as mine backfill or in the rehabilitation of a surface mine. Recent advances in tailings management have focussed on thickening the tailings prior to deposition. This approach is typically referred to as "thickened tailings" or "sloped deposition". These systems rely on thickened slurry being deposited in relatively thin layers on a sloped bed to allow consolidation via both gravity drainage and solar drying. Over the past decade significant advances have been made in the technology associated with thickening dilute slurries, thickeners have become more efficient and flocculants more effective and the production of high density pastes is now possible with the developments in the mechanical systems that can both produce and pump high density material, these advances have aided the development of thickened tailings making the whole process more affordable. Ciba Specialty Chemicals has developed a range of rheology modifiers, which could play an important role in this type of tailings management process. These products are added at a controlled dose, in line into the thickened slurry at a point determined through laboratory work and plant trials, but usually close to the discharge pipe or launder. The products modify the surface properties of the tailings producing a high yield stress material with controllable stacking and rapid water release and recovery. The application known as Ciba ® RHEOMAX™ ETD technology has been investigated on a range of mineral ore types in South Africa, South and North America, Australia and Europe at both laboratory and plant operational scale, amongst the benefits recorded were.  Maximisation of existing disposal areas.  Improved and rapid recovery of water or liquor.  Enhanced co-disposal of coarse and fine material.  No reworking of disposal areas.  Faster trafficable surfaces.  Better land rehabilitation and re-vegetation introduction.