Ore reserve estimation for mine planning at Ghana Consolidated Diamonds Limited, Akwatia

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At Ghana Consolidated Diamonds Limited (GCD), production figures for the past four years indicate that there is a significant difference between the estimated ore reserve and what is actually obtained at the end of a mining programme. While other unit operations like the mining method and the efficiency of the treatment plants may be contributing to this disparity, one of the major reasons could be that the current estimation method is not adequately reliable. The objective of this thesis is to assess the current method of ore reserve estimation on the mine and to investigate other estimation method that may be applicable. The standard arithmetic method, which is the current estimation method on the mine, has been used to estimate reserves in a selected area of the GCD concession. The triangular and geostatistical methods were used to estimate the reserves within the selected area. The justification for choosing the triangular method has been outlined. The applicability of geostatistical method has also been justified by the fact that the grade distribution of the different geological regions within the selected area could be fitted with the spherical semi-variogram models. It is suggested that the current estimation is good since the tonnages estimated using this method 1ie in between those of the other two methods However, the estimated grades and the variances were least in the case of geostatistical method. If the drilling programme could be intensified to produce adequate samples, geostatistics could serve as a tool to narrow the observed disparity between estimated and mined grades at Ghana Consolidated Diamonds Limited.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology, Kumasi, in partial fulfilment of the requirements for the award of Postgraduate Professional Diploma in Mining Engineering, 1990