Evaluation of ore transport options from Kwesi Mensah Shaft to the mill at the Obuasi mine

This article illustrates the application of the analytic hierarchy process (AHP) to evaluate surface ore transport options for the underground mine at AngloGold Ashanti's Obuasi mine in Ghana. The mine currently transports about 175,000 tpm of ore from four shafts to the mill using contractor trucking. The mine's current business plan requires the underground ore production to be increased from 175,000 to 220,000 tpm. The extra tonnage is to feed the new tailings sulphide plant, located adjacent to the existing mill. This change necessitated a review of ore transport options between the Kwesi Mensah Shaft and the mill. The four options that were considered are the continued use of contractor trucking, purchasing mine-owned trucks and using surface or underground conveyors. The evaluation criteria were categorised under the broad areas of economic, environmental and technical criteria. Since multiple options and criteria had to be evaluated simultaneously, it was appropriate to use the AHP for the selection process. Five experts on the mine participated in the evaluation exercise which revealed that surface conveyors were the most-favoured option. This is the first time that a more structured approach has been used successfully for equipment selection at Obuasi mine and there is adequate scope for future use of the AHP technique on the mine in mine planning or equipment selection.