Risk reduction in Sechahun iron ore deposit by geological boundary modification using multiple indicator Kriging

Abstract

Uncertainty on the geological contacts and the block volumes of the models along boundaries is often a major part of the global uncertainty of reserve estimation. This work introduces a geostatistical technique that has been developed and tested in an iron ore deposit at Bafq mining district, in central Iran, and that, based on a probability criterion, helps to objectively model the geometry of this iron ore deposit. The main problem in reserve estimation of this ore body is its geometrical modeling and uncertainty in geological boundaries. This work deals with the geostatistical method of multiple indicator kriging, which is used to determine the real boundaries of ore body in different categories. This approach has potential to improve project performance and decrease operational risk. For this purpose, the ore body is separated into two categories including rich iron zone (w(Fe)>45%) and poor iron zone (20%<w(Fe)<45%). It significantly benefits to decrease the risk of reserve evaluation in the deposit. This case study also highlights the value of multiple indicator kriging as a tool for estimates the position of grade boundaries within the deposit. Comparison of the resultant probability maps with the real ore/waste contacts on the extracted levels shows that the first indicator model could separate the whole ore body (poor plus rich) from the waste zone by probability of more than 0.35, which concludes the total reserve of 53 million tons. The second indicator model applied to separate the rich and poor domains and the results show that the blocks with the estimated probability of equal to or more than 0.4 lay within the rich ore zone consisting of 15.8 million tons reserve.