An analysis of the size of gold grains in the Offin Placer Deposit of Dunkwa Goldfields Limited and its effect on the dredge plant recovery

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The size of gold grains in the Offin placer deposit and its effect on the treatment plant of Dunkwa Goldfields Limited, Dunkwa-on-Offin, were investigated. Samples were taken from Dredges 5 (Middle Offin), 6 (Lower Offin) and 7 (Upper Offin). These samples were treated and the gold grains recovered for further analysis. Microscopic and sieve analyses were the sizing techniques employed in analyzing the sizes of the gold grains. Statistical methods were used in analyzing the distribution of gold grains in the deposit. The analyses revealed that, the average grain size shows little variation from Upper Off in (250μm) down the Offin River to the Lower section of the Offin (185μm). The Dredge treatment plants on Dredges 7 and 5 were found to be suitable. Dredge 6 showed some inconsistencies. Mineralogical study on the deposit showed that the associated minerals in the three sections were the same the only difference being that, the sizes of the mineral grains decrease from the Upper to the Lower Offin sections. Quartz formed the bulk of the gangue minerals in the deposit. The shapes of the minerals in the deposit were found to be angular to sub-angular.
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