Spatial Modelling of Central Block Using Geostatistics, Pottangi Bauxite
Deposit, Koraput, Odisha
Abstract
The Koraput district is one of the most important centres for bauxite
mining in Odisha. Bauxite deposits of Pottangi are located In Navdapur
taluka going northwards towards Pottangi village which is a part of
Koraput district,Odisha,situated on ‘Sirimanda Parbat’. The mines at
Pottangi are under the charge of National Aluminium Company Limited
(NALCO). The present study deals with the geostatistical modelling of
the Central Block of the Pottangi bauxite deposit, Koraput district,
Odisha while taking into account the various lithological structural and
textural characteristics of the area. Exercises on population modelling
showed that Al2O3, SiO2 and TiO2 exhibited skewed distributions while
Fe2O3 displayed a symmetric distribution. Log-transformations were then
performed on geo-variables displaying skewed distributions. The
interrelationships and the degree of association among the variables
have been established through bivariate analysis.3-D omni-directional
experimental semi-variograms of Al2O3, SiO2, Fe2O3 and TiO2 were
constructed at 50m lag interval. For these experimental semi-variograms
spherical models were fitted through Point Kriging Cross-validation
techniques using GEXSYS software. The entire deposit was divided into a
number of blocks with optimum Selective Mining Unit. The result of block
kriging was used to compute an ore inventory and to establish grade
tonnage relationships estimating the quantity of bauxite ore and waste
material, average grade of the ore and waste to ore ratio following a
step-wise integration of the block grade frequency distribution of a
range of grades. The following work done represents advanced
geostatistical techniques for improved modelling of the Central Block of
Pottangi Bauxite deposit, Koraput, Odisha. The geostatistical techniques
used helps in a better evaluation of reserve estimates.