Pilot Point Optimization of Mining Boundaries for Lateritic Metal Deposits: Finding the Trade-off Between Dilution and Ore Loss

Abstract

Geological contacts in lateritic metal deposits (footwall topographies) often delineate the orebody boundaries. Spatial variations seen in such contacts are frequently higher than those for the metal grades of the deposit. Therefore, borehole spacing chosen based on the grade variations cannot adequately capture the geological contact variability. Consequently, models created using such boreholes cause high volumetric uncertainties in the actual and targeted ore extraction volumes, which, in turn, lead to high unplanned dilution and ore losses. In this paper, a method to design optimum ore/mining boundaries for lateritic metal deposits is presented. The proposed approach minimizes the dilution/ore losses and comprises two main steps. First, the uncertainty on the orebody boundary is represented using a set of stochastic realizations generated with a multiple-point statistics algorithm. Then, the optimal orebody boundary is determined using an optimization technique inspired by a model calibration method called Pilot Points. The pilot points represent synthetic elevation values and they are used to construct smooth mining boundaries using the multilevel B-Spline technique. The performance of a generated surface is evaluated using the expected sum of losses in each of the stochastic realizations. The Simulated Annealing algorithm is used to iteratively determine the pilot point values which minimize the expected losses. The results show a significant reduction in the dilution volume as compared to those obtained from the actual mining operation.

Digital Economy as a Factor in the Technological Development of the Mineral Sector

“…Contemporary research in minerals processing aims to improve the environmental economic and energy efficiency of technological processes, as energy and water requirements are very important in rock grinding and flotation processes (Dagasan et al 2019). Work is being carried out to replace environmentally hazardous extraction and enrichment technologies with cleaner alternatives.…”

“…The implementation of new processing technologies is leading to a 15-20% reduction in unit water consumption and a 30-50% reduction in unit electricity and reagent consumption. It is anticipated that productivity at processing and enrichment facilities will increase by 10-40% (Dagasan et al 2019).…”

Automatic Parameter Tuning of Multiple-Point Statistical Simulations for Lateritic Bauxite Deposits

“…The reason why MPS could be interesting in this particular case is that several sites have already been mined out, and the topographies of the footwall contact exposed after the mining operations can be considered as analogues to the footwall contact of a future mining area. In addition, the data sets collected from such mines usually include several variables such as exploration boreholes, exhaustive geophysical data, and production control boreholes [13][14][15]. In order to account for the multivariate nature of the modelling problem and the necessity to simulate a continuous variable, it was decided to use the Direct Sampling (DS) algorithm [10] in this work.…”

Modelling of bauxite seam attributes and quantifying in-situ ore volume uncertainty in the presence of geophysical information

“…Therefore, the geostatistical model for the ED bauxite top elevation data should be a nonstationary RF, and the UK approach should be used to generate its predicted values. Considering the UK system, splitting the residuals from the drift is critical, as it directly affects the accuracy of the final predicted values (Matheron 1971; Armstrong 1984; Dagasan et al 2018b). We have used maximum likelihood approach, which is a parametric method (Kitanidis 1983) to estimate the coefficients of a drift model.…”

“…Unlike the conditional simulation algorithms where the variogram model is a requirement, the structural information (in this case, a training image) required for the MPS simulation was obtained from the footwall topography of the adjacent mining area which was previously mined. Dagasan et al (2019b) and Dagasan et al (2018a) employed the direct sampling approach, which is an MPS algorithm to quantify the uncertainty in the bauxite footwall contact, and used this uncertainty to generate the optimum dig-lines for the ore extraction at Weipa.…”