Groundwater flow model for Konkola underground copper mine, Zambia

Synopsis

Konkola Underground Copper Mine is located in the Copperbelt Province of Zambia and has the largest known ore reserves of all the eight operating mines owned by Zambia Consolidated Copper Mines Limited. Konkola has long been recognised as one of the wettest, if not the wettest mine in the world. An average of 360,000m³/d is pumped from the mine, giving a ratio of 113:1 of water to ore hoisted. The large volumes of water encountered and expected during mining constitute a major cost in mine planning and development.

Mining has now reached a depth where management decisions concerning future production require as accurate an assessment as possible of groundwater inflows and a numerical model of groundwater flow to the mine has been developed, as outlined by Mulenga and de Freitas (1): this model is currently undergoing refinement. Many problems were faced in designing the model and this paper describes the decisions that had to be taken in order to build the model for simulating groundwater flow to and through the mine and predicting water level drawdown; and mine discharge.

The paper describes four aspects of this work:

• 1. The decisions required to represent the geology of the mine in the model.

• 2. The decisions required for the input parameters to be used.

• 3. The calibration of the model.

• 4. Preliminary results from the model. Relevant aspects of field geology, mining engineering and associated hydrogeological studies are described, their inter-relationship explained and the uncertainties associated with them demonstrated.