Ore reserves estimation of the Nam Nga coal deposit, Lao PDR, using geostatistical method

Abstract

This research study focuses on estimating the coal deposit quantity and qualities as CV and AC at Nam Nga coal deposit, Lao PDR using OK and SGS geostatistical methods. A total of 295 assays data from 51 exploration drill holes collected from LID Company were used. The results reveal that OK produces geological resource of 2.2 MT with an average CV of 3,733 kcal/kg and an average AC of 48.68 %. The mineable reserve computed from OK’s ultimate pit design and pit adjustment are 0.55 MT. The OK method produces 9.32 MT of wastes, yielding a stripping ratio of 10.4:1. The SGS method produces 2.2 MT of geological resource with an average CV of 3,769 kcal/kg, and an average AC of 46 %. The SGS’s ultimate pit design and pit adjustment generate 0.54 MT of mineable reserve. The SGS generates wastes 9.5 MT, yielding a stripping ratio of 10.1:1.

In comparison, the OK and SGS produce the very similar results for coal grades estimation, mineable reserve, and stripping ratio calculation. However, OK generates smoother maps when most of the estimated values moving toward the mean value. SGS method is better in preserving a local variation, as can be seen in the overall simulated variance closed to the original data variance. And SGS also provides a multiple realization maps which bring a benefit for accessing the risk involved.