Geostatistical mineral reserve estimation - a case study at Ashanti Goldfields Company ( AGC)

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The Obuasi Mine of Ashanti Goldfields Company (AGC) exploits part of the Birimian auriferous deposit of Ghana by underground method. Knowledge of the quantity and quality of the orebody is obtained through extensive exploration, development and sampling. The grade and the tonnage of mining blocks are estimated using weighted average method. One of the issues which have been brought into focus by the current expansion programme of the company is the need to find an alternative mineral estimation method. The main objective of this thesis is to investigate the applicability of geostatistics as alternative mineral reserve estimation at AGC. Initially, the regional geology, sampling practice and the current estimation method in use at Ashanti Goldfields Company (AGC) were studied. Subsequently, geostatistical technique was applied to estimate the grade and tonnage of some chosen mining blocks at the George Cappendal Shaft (GCS) area of AGC. The results obtained by using the geostatistics correlated well with the results obtained from the weighted average method employed by the mine. It is suggested that geostatistical method is applicable at AGC and therefore can be adopted by the mine to give reliable estimates and to serve as a basis of comparison with the other methods.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirement for the award of Postgraduate Diploma in Mining Engineering, 1994