Open pit mine planning and design - a case study

Abstract

Mine planning and design facilitate the exploitation of mineral deposits at the lowest possible cost with the objective of maximising profit and optimising the life of a mine. Zone40 Mine is currently an existing small scale underground mine located at Bawku-West in the Upper East Region of Ghana. The current fall in gold price coupled with increased operational cost have necessitated mining only the high grade areas in order to make some profit. A potential gold resource (Ridge-2 Orebody), 40 km from the existing processing plant, exploitable by open pit mining method with less operating cost, has been identified to obtain more ore to feed the processing plant. The aim of this thesis is to design an optimal open pit and generate a production schedule for the extraction of the Ridge-2 Orebody. Geological, geotechnical and economic parameters, Whittle, Surpac and MineSched software were used for pit optimisation, final pit design and the generation of a production schedule, respectively. The results show that the Ridge-2 Orebody is economically viable. The optimal pit contains 1 145 425 tonnes of ore at an average grade of 2.17 g/t. The final pit contains 1 041 742 tonnes of ore at an average grade of 2.03 g/t. The production schedule generated 1 041 742 tonnes of ore at an average grade of 2.03 g/t, at a mining rate of 2 608 073 tonnes per annum, for a period of 4.9 years. It is therefore recommended that the final pit designed be used for the extraction of the Ridge-2 Orebody.