Abstract

HANSMANN, K.. When should uniform conditioning be applied?. J. S. Afr. Inst. Min. Metall. [online]. 2016, vol.116, n.7, pp.645-654. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2016/v116n7a6.

Blindly applying any methodology to estimate the recoverable resources of a mineral deposit without considering the suitability of the approach to the deposit being evaluated can render misleading results. While 'running the software' provides an answer, one should, amongst numerous other considerations, understand the impact the underlying distributions and assumptions have on the validity of the result. Uniform conditioning (UC) is a nonlinear estimation method that models the conditional distribution of smallest mining unit (SMU) block grades within panels, and localized uniform conditioning (LUC) places these SMU at plausible locations within a panel. The localization process does not improve the accuracy of the UC result, but rather presents the result in a more practical format; particularly for use in mine planning. A case study was carried out to compare the suitability of UC and LUC on two hypothetical data-sets. The data-sets are simulated realizations of a normal grade distribution and a highly skewed lognormal grade distribution which are akin to grade distributions found in mineral deposits. The estimation methods were applied to both data-sets, and the results compared with the actual grades of the simulated realizations. This paper presents an overview of UC and LUC, with discussions around the case study results.

Keywords : change of support; Gaussian anamorphosis; localized uniform conditioning; lognormal distribution; normal distribution; uniform conditioning.

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