Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
Print version ISSN 0038-223X
SARAVANAKUMAR, P.; BROWN, G.J. and VAN ECK, G.. Sample support size and spacing determination for resource development of a marine placer gold deposit. J. S. Afr. Inst. Min. Metall. [online]. 2014, vol.114, n.1, pp.7-18. ISSN 2411-9717.
Successful resource development for a marine placer gold deposit requires continuous sampling throughout the life of mine. The cost of sampling marine placer gold deposits is exponentially more expensive than for terrestrial placer and non-placer gold deposits and thus warrants a comprehensive cost-effective sampling strategy. The optimum sample support size depends on expected gold grade, desired confidence limit, and shape and size of the gold grains. The optimum sample spacing depends on the continuity of the deposit, required confidence limit, and cost-benefit analysis of a sampling programme. The current study combines sample support size and spacing determination for resource development of a marine placer gold deposit. The study used two methods to calculate the sample support size - modified Gy's formula and the approach pioneered by Clifton et al. (1969). Using historical drillhole data, a geostatistical simulation of a representative geological/mineralization domain was created on an extremely dense grid. The simulation realizations were validated using statistical, spatial, and graphical methods. Additional sample support sizes were then created by combining adjacent simulation nodes to form double, quadruple, and octuplet multiples of drill diameter sizes. The simulations were sampled at three different spacings: 100 m x 100 m; 50 m x 50 m; and 25 m x 25 m and then each sample set estimated into 50 m x 50 m blocks with ordinary kriging. A comparison between the actual and estimated block results was then carried out and the confidence of each sampling pattern (sample spacing and sample support size) determined. A cost-benefit analysis was then used to determine the optimum sampling strategy for the marine placer gold deposit.
Keywords : sampling; support size; spacing; marine placer gold.