Nonlinear disjunctive kriging for the estimating and modeling of a vein copper deposit

ABSTRACT Estimation of mineral resources and reserves with low values of error is essential in mineral exploration. The aim of this study is to estimate and model a vein type deposit using disjunctive kriging method. Disjunctive Kriging (DK) as an appropriate nonlinear estimation method has been used for estimation of Cu values. For estimation of Cu values and modelling of the distribution of Cu in Chelkureh, samples have been taken from 48 drill holes in Chelkureh, and the values of Cu have been analyzed. Resulting data from analyzing Cu values were converted to standard normal values using Hermite polynomials. Variography has been done in the Chelkureh deposit. After studying of variograms in different directions, it was found out that the ore deposit has a mild anisotropy. The best-fitted variogram model was considered for disjunctive kriging estimation. The model consists of a pure nugget effect with 0.46 amplitude plus a spherical scheme with sill 1.20 and range 140 m. Consequently, a three-dimensional model of estimated value and error estimated value was provided by disjunctive kriging to divide the ore into an economic and uneconomic part. The models based on estimate of DK method in the study area exhibited an increasing trend of concentration from the centre to North. Finally, validation of the disjunctive kriging carried out by using cross validation. The result showed that the correlation of estimated values and real values was strong (63.4%).