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|Title: ||A Geostatistical Approach to the Optimization of Grade Control Sampling at Sansu mines|
|Authors: ||Adofo, Richard Amoako|
|Issue Date: ||27-Sep-1994|
|Series/Report no.: ||2091;|
|Abstract: ||The Sansu Mines of the Ashanti Goldfields Company Ltd. (AGC), Obuasi in the Ashanti Region, comprises 5 pits which are currently in operation whilst resource estimations however have been prepared for 6 other pits which are to be mined in the near future.
Most of the pits are within low grade mineralization from which more and more mining will occur in and around marginal areas. Quality and quantity of sampling for grade control would therefore have to be reassessed to increase company’s profitability margins.
The current study is aimed at using geostatistical approach to optimize grade control ripline sampling within three of the pits which have varying lithological characteristics. These pits are (1) the Nhyiaso orebody - a granitic intrusive body, (2) 4 & 5 lodes of the Anyinam pit located largely within Birimian metasediments, and (3) the Sansu Pit, located within the metavolcanics of the Birimian.
The study involved statistical and geostatistical analysis of the ripline sampling assay values taking cognisance of the geological characteristics of the pits to determine whether the current sampling density is adequate to support ore estimation.
The variography and precision estimation showed that the current sampling interval of 10 m along strike for the Nhyiaso and Anyinam are adequate. Sampling interval across strike could be maintained at 2 m for Nhyiaso, however, the presence of pegmatitic type granitoids would call for a sampling interval of 1 m across strike, to obtain a better grade control. Within the 4 & 5 orebody sampling interval could be increased from 1 m to 2 m since there is not much difference in precision between the two intervals. Geostatistical analysis on the assay grades from the Sansu Pit was inconclusive.
Steps to improve grade controlling practices within the open pits are suggested.|
|Description: ||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 the Degree of Master of Science in Mineral Exploration, 1994|
|Appears in Collections:||College of Engineering|
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