Nickel Laterite Resource Estimation Using Inverse Distance Weighted (IDW) and Ordinary Kriging (OK) Methods in East Luwu Regency, South Sulawesi, Indonesia

Abstract

Nickel is a major mining commodity in Indonesia with abundant reserves, especially in Sulawesi which contributes to the national economy through the stainless steel and electric vehicle sectors. This study aims to analyze the estimation of nickel laterite resources in East Luwu Regency using the Inverse Distance Weighted (IDW) and Ordinary Kriging (OK) methods to analyze the quality and effective methods for estimating nickel laterite resources. The data used were 2.616-grade samples for each borehole interval and analyzed through descriptive statistics, variogram fitting, estimation model building, and laterite nickel resource estimation analysis. The estimation results of the IDW method with Cut-off Grade (COG) showed the volume and tonnage acquisition in the limonite zone of 4.593.710 m3, 5.896.667 tons, while in the saprolite zone of 5.058.249 m3, 6.317.770 tons. The Ordinary Kriging (OK) method shows the acquisition of volume and tonnage in the limonite zone of 4.602.227 m3, 6.203.349 tons, while in the saprolite zone of 5.674.171 m3, 6.647.641 tons. Based on the estimation results, the OK method obtains larger volume and tonnage results than the IDW method. This happens because the OK method uses the principle of spatial correlation of data. It not only focuses on the closest