Confined yield stress lubrication flows for cement paste backfill in underground stopes

Abstract

Along with the increasing excavation of underground spaces, the mining industry has developed various techniques for refilling these voids. One of them is cemented paste backfill (CBP), coming from the mixing of tailings with water and a binder. These pastes are then transported to underground cavities through pipes and into voids, which they fill in a layering pattern. In this paper we explore the capabilities of a simplified thin-film model to describe the evolution of the paste shape within the stope. The mathematical difficulties are to include the yield stress behaviour of the paste and to deal with the walls in a consistent manner. We show the possible behaviours of the associated solutions to these problems, governed by 2 dimensionless parameters. Two regimes of filling are exhibited, when studying physical parameters typically used in CBP. Finally, we compare the simulations with physical experiments performed in a scaled lab setting using realistic tailings pastes from lead–zinc and nickel mines in North-West China. A good agreement is found between simulations and experiments.