Utilization of mill tailings, fly ash and slag as mine paste backfill material: Review and future perspective

An enormous amount of waste materials (tailings, fly ash and slag) are generated during mineral processing, power generation and metallurgical processes. A vast literature on utilising mill tailings for paste backfilling, fly ash and slag as partial replacement to cement is available. However, a detailed review on the application of mill tailings, fly ash and slag as mine paste backfill material has been lacking. This article provides a critical review of these industrial wastes’ utilisation as paste backfill material for backfilling of the underground mine voids. The properties of backfill materials affecting the paste backfill performance, advancements made in geomechanical, microstructural properties, strength prediction, leaching and economic aspects are scientifically reviewed. In addition to the above, the effect of alternative binders, specifically fly ash and slag, modification of paste backfill using alkali activator, superplasticizer, admixture and fibre reinforcement are comprehensively reviewed. The review ended with some future research directions in mine paste backfilling, especially applying natural and artificial additives for early strength development, strength and flowability prediction using statistical and artificial intelligence tools, leachates stabilization and geochemical modeling of leaching. Hence, this review would help in further application of such industrial waste materials for mine paste backfilling.