AN ANALYSIS OF HOLE DEVIATION AND ITS EFFECT ON PRODUCTION

Oppong, M. N and Agyei, G.

Abstract

An analysis of hole deviation and its effect on production at Chirano Gold Mines Limited has been carried out. Chirano Gold Mines Limited employs sublevel stoping and open stoping methods where production holes are drilled in the form of rings. Complete control of borehole directions sometimes was not obtained during drilling. This problem caused shortfalls in the burden, spacing and hole depth parameters. The boretrak instrument was used to measure the drill hole deviations at the stopes during this study. The analysis was based on 29 holes in 5 rings which recorded total deviations of 4.4 m, 1.9 m and 16.8 m in the burden, spacing and hole depths parameters respectively. The result showed 31.2% deviation in the burden, 2.8% deviation in spacing and 3.2% deviation in the hole depth. The effect of the hole deviations on production was portrayed by an increased output of 1965.85 t of materials representing 23% deviation from the planned. This result also showed that there would be ore dilution which may decrease the mill head grade. This undoubtedly would increase the cost of production of the mine through extra energy requirement to blast and to process these waste materials. From the results obtained, it was recommended that more boretrak surveys should be carried out for informed decisions to be made by planners during the preparation of the charge plans. Also, deviations in the toe burden should be minimized by drillers using competent machines to drill accurately. Read full PDF

Keywords: hole deviation, production, burden, spacing, hole depth, boretrak instrument

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