Efeito da adição de reagentes agregantes e de ligantes sobre a consistência em pastas minerais

Abstract

Current deposition of tailings from mineral processing operations is still based upon the sub aqueous disposal of tailings into tailings ponds, created by dams erected in natural valleys. On the other hand, surface disposal of tailings as mineral pastes has increasingly been seen as an advantageous alternative to conventional sub aqueous disposal forseveral reasons. Some of these advantages include improved water recovery, much smaller tailings areas footprints, and diminished environmental impacts, reduced overall costs and, for the case of cemented paste fill applied to underground works, increased orerecovery. The use of aggregants as polymeric flocculants and non-polymeric coagulants enhances solid-liquid separation techniques, eventually improving mineral paste production and transport operation.The addition of binders such as Portland cement, fly ash, meta-kaolin, silica fume, lime, and others can promote paste fill material with adequate resistance so it can be used as a filler of underground and surface cavities. Blends of cemented pastes, waste rocks and alltype of tailings (slimes, flotation tailings, etc) are possible. The objective of the current work is evaluating the different aggregants agents and binders performance for paste production to be used in the disposal of iron ore tailings. The basic methodology employed consisted of slump testing for paste consistency determination, rheological characterization and settling rate determination. As a support for the basic methodology, factorial design experiments were performed in order to assess response surfaces of the several parameters evaluated and their relationships throughout the current work. These parameters chiefly included the determination of the effects of aggregants (a coagulant and a polymeric flocculant) on the responses of consistency, settling rate and viscosity of the pastes prepared, and the influence of binders (metakaolin, fly ash and Portland cement) on the compression resistance of specimen. The effect of factors such as pH, solid concentration (as percent solids), content of fines (<37µm) on consistency (% of slump) and rheological parameters of the solid-liquid mixtures (apparent viscosity and rheological behavior) was also investigated.