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, University of Alberta, Edmonton, and Australian Centre for Geomechanics, Perth, pp. 244-256, https://doi.org/10.36487/ACG_repo/2355_18
The number of paste operations has grown since the early application of thickened tailings for backfill in the 1970s. Backfilling underground void stopes with paste is often a competitive backfill option compared to alternatives. Therefore, having suitable tailings is critical for paste backfill. Ideally, a paste system delivers a homogeneous, non-settling fluid with good flowability. Once placed, the paste should generate little bleed water and develop the required strength using the least amount of binder possible. The paste’s quality depends on the tailings’ properties, like mineralogical composition, related to the ore deposits’ geological evolution and formation. For example, epithermal gold systems are formed in a proximal volcanic setting and are triggered by an intense, hot, fluid migration process. This type of deposit has a different mineralogical footprint and alteration surrounding than an orogenic gold deposit, which experienced a different alteration and ore formation history, being formed along major fault zones. These differences, in addition to the required ore comminution processes, are reflected in the tailings produced from a given ore body and, therefore, impact the characteristics of the available tailings material to make a paste backfill product. Modern, state-of-the-art paste backfill admixtures are increasingly used to optimise paste backfill mix designs and to manage problematic tailings properties. This paper outlines the impact of using water-reducing admixtures on the solid content increase and strength gain of paste. Data from 13 different mine sites for three common deposit types – orogenic gold Iodes, VMS-SEDEX deposits, and epithermal deposits – have been collected for this study. Special attention is given to the impact of their particle size and their phyllosilicate content on the water-reducing potential and strength.
Keywords: paste backfill, particle size distribution, mineralogy, admixtures, optimisation
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