The Use of Geostatistical Simulation to Optimize the Homogenization and Blending Strategies

Abstract

Homogenization piles are largely used in the mining industry for variability reduction in the head grades feeding the processing plants. Various methods are found for homogenization piles design and most fail to incorporate the in situ grade variability intrinsic of a mineral deposit. The methodology proposed combines longitudinal piles and geostatistical simulation to emulate the in situ and the pile reclaimed grade variability. Variability reduction in large piles is based on the volume-variance relationship, i.e. the larger is the support the smaller is the variability. Based on a pre-defined mining sequence to select the blocks that will form each pile for each simulated block model, the statistical fluctuation of the grades derived from real piles can be simulated. These piles are characterized by their form, size (length and height) and number of layers. Using this methodology, one can evaluate within a certain time period the expected grade variability for various pile size and also the internal grade variability when a given pile is reclaimed. Results from a case study at two large iron mines operated by Vale proved the adequacy and functionality of the method. It is demonstrated the rate of variability decrease as the pile size increases and the internal grade variability to a given pile size, with different numbers of layers.