Computer aided geostatistical modelling and resource evaluation of Durgamanwadi bauxite deposit, Kolhapur District, India

摘要

The eastern plateau of Durgamanwadi bauxite deposit, Kolhapur district, India corresponds to the regional geology of Deccan traps between Upper Cretaceous and Lower Eocene. The deposit is residual concentration type formed by prolonged chemical weathering of Deccan trap basalt at or near the surface under tropical to sub-tropical climatic conditions. Sample value compositing in respect of percent Al_2O_3, percent TiO_2, percent Fe_2O_3 and percent SiO_2 has been carried out considering the average of the entire weighted lengths of samples with Al_2O_3 content more than 45 percent and SiO_2 content less than 10 percent. Classical statistical modelling revealed a normal distribution fit for Al_2O_3, TiO_2, Fe_2O_3 variables and a two-parameter lognormal fit for SiO_2. The geostatistical resource evaluation of the bauxite deposit includes spatial structural modelling, mineralized block boundary delineation, block kriging, calculation of ore inventory and establishment of grade-tonnage relations. The global mean kriged estimate and kriging variance for Al_2O_3, SiO_2, Fe_2O_3 and TiO_2 contents are determined to be 50.90 percent and 2.17(percent)~2; 4.30 percent and 1.00(percent)~2,. 14.56 percent and 2.14(percent)~2; 4.36 percent and 0.048(percent)~2 respectively. An ore inventory and a series of grade-tonnage relations at various probabilistic cutoff grades have estimated a total tonnage of 3.13 million tonnes of bauxite at a cutoff grade of 45.6 percent Al_2O_3.