Perpustakaan Digital ITB

Mining industry is an industry with a high risk so that it needs an exploration activity which provides comprehensive information about mineral resources. The mineral resources of ore deposit are related to their distribution, concentration, and geometric conditions so that the planning and implementation of mining methods can work well. The deposition of nickel laterite is strongly influenced by the degree of weathering that causes the ore geometric and distribution become heterogeneous, additionally sometime it looks like the folded deposit. This folded deposit is expected to be modeled and analyzed using the unfolding transformation so that the transformed data become more homogeneous prior to kriging estimation. The unfolding method used in this study is affine transformation. This transformation can change the surface of an irregular plane into a flat one by determining connective points, i.e. initial coordinates and the coordinates of the projection, on the surface. From the connective points, the area of original surface in two-dimensional shapes can be found. The transformed data within this shape is then estimated by ordinary kriging method for each enrichment zone, and then be back transformed to get the original shape and distribution. The estimation results with unfolding techniques for estimated Ni grade provided error variance 0.036 %2 and 0.094 %2, and for estimated Fe grade is 38.49 %2 and - 25.30 %2 in limonite and saprolite zones respectively. While the error variance for folding (original) condition for estimated Ni grade is 0.037 %2 and 0.095 %2, and for estimated Fe grade is 42.03 %2 and 26.87 %2 in limonite and saprolite zones respectively. From these results, the study showed that kriging estimation using unfolding technique for laterite nickel deposit gives better results in term of producing the less error variance.