Estimations of limestone resources using three dimension block kriging method, a case study: Limestone sediment at PT Semen Padang

Abstract

Making of block model was performed by geostatistic approach using kriging method to estimate and modeling of limestone source quality at Karang Putih Hill. Modeling and counting of source were based on three-dimension block model concept which was divided into block units with grid size 100 100 15 m which was appropriate with the size of mining block at location of the study. Variable used for limestone source estimation were CaO, SiO2and H2O levels, according to conditions of raw material quality which has been specified.The result from variogram analysis showed that spatial characteristic of CaO, SiO2 and H2O levels in limestone had nugget effect percentage of 47, 36%, 30, 92%, dan 33, 3% with range 145 - 230 m and range for vertical direction 21 - 40 m. Percentage (%) error of limestone estimation with confidence level 95% for CaO level were 54, 74% 0, 04%, SiO2: 0, 72% 0, 04% and H2O: 0, 36% ± 0, 007% respectively. Limestone resource quantity estimation at Karang Putih Hill up to elevation 214 meters above sea level which fulfilled the standard quality of CaO level ≥ 48 %, SiO2 level < 10%, and H2O level < 6 % was 158, 01 million ton, while tonnase in the form of 799, 94 thousand ton of silica and 1, 17 million ton of basalt.