Design Considerations for the Implementation of Tailings Based Wetcrete at Harmony's Target Mine

Abstract

The Target Mine orebody is situated approximately 2400 m below surface and is accessed via a vertical shaft and decline system, totalling approximately 6000 m in length. This requires that all modes of transport be optimised. As a result of the heavy burden on the mine's logistical transport system, the mine was unable to deliver sufficient quantities of wetcrete material to the underground batching plant. This resulted in a relatively large backlog of wetcrete work building up over a number of years. The mine utilises a system of batching wetcrete underground using conventional material such as sand, cement and chemical additives.Through creative thinking, a system was designed to replace the current wetcrete infrastructure with a surface batching plant where cycloned tailings are used to prepare a wetcrete mix on surface. This system promises not only to impact positively on the mine's logistical system, but also reduces the direct cost of supplying wetcrete material underground. This paper discusses the philosophy behind the design and implementation of tailings based wetcrete as well as the quality assurance requirements at Target Mine.