A historical perspective of diamond mine dewatering design and guidelines for modern diamond mine (2021)

Dr Kym L Morton
KLM Consulting Services Pty Ltd, PO Box 119, Lanseria, 1748, South Africa.

Abstract
Diamond mining in hard rock has been practiced since the late 1800’s. Mine dewatering design has been an important consideration in the mining of kimberlites.
The mining of kimberlites tends to follow a specific methodology. Diamonds are mined open pit to about 350m below ground level, then, when the cost of driving tonnes up roadways to the plant becomes uneconomic a shaft is sunk and methods such as blast hole open stoping, sub level caving, block caving or a combination is used.
Each mining method has a specific effect on the groundwater surrounding the pipe. The hydrogeology of typical kimberlite mines is detailed and the methods of keeping water away from the mine workings are described. Early underground mines used water tunnels, connected by water passes to divert rainwater and near surface groundwater from the mine workings. Shafts with multi-stage pumping levels were used to pump water from the deepest sections of the mine. At Finsch mine a decline, 650m deep water ring-tunnel (combined with a conveyor belt level) and deep pumping boreholes were used to dry the initial block cave to 720m below surface.
Using experience gained on the deep mines, modern dewatering techniques have been developed and managed using monitoring networks to enable accurate management of underground water including the reduction in mud rush risk.
This paper summarises the techniques used to manage pit and underground water, its links with mud rush occurrence and lessons learnt over the last 120 years. It concludes with a good practice dewatering design and water management strategy for modern mines.
Keywords: Monitoring, Groundwater, Feasibility Studies, Environment, Optimisation.

Morton, K.L. (2021) ‘A historical perspective of diamond mine dewatering design and guidelines for modern diamond mine’, SAIMM, 2021.