RELIABILITY ANALYSIS OF THE DILUTION GRAPH METHOD FOR OPEN STOPE DESIGN: A CASE STUDY OF MALEYEVSKY MINE

Abstract

The open stope mining method is characterized by a large extraction rate and mostly unsupported walls, making it very susceptible to unplanned dilution. Unplanned dilution leads to low profitability of the mining operations. Therefore, it is essential to develop design methods that facilitate minimizing dilution. One of the most popular (commonly used in practice) stope design methods is the empirical dilution graph ELOS. However, this method does not consider the inherent variability of the design input parameters, such as the rock mass properties, due to the various difficulties of field measurements. Consequently, the performance of the stopes designed with this method is not consistent. If a reliability index for desirable stope design could be determined, valuable information on the probability of meeting the targeted dilution level could be found. This thesis uses the First-Order Reliability Method to determine the reliability index associated with open stope design through the dilution graph design approach. To this end, the Maleyevsky mine, located in northeast Kazakhstan, is used as a case study. The parameters used for the reliability analysis are the Modified Stability Number (N’), Hydraulic Radius (HR), and the Actual dilution (Dc). The results indicated that reliability indices vary between 0.1-4.63 depending on the rock domains pertaining to the study area, while the corresponding probability of unplanned dilution values range from 0.0001% to 51.22%, respectively. Performance thresholds for each level of dilution were suggested. It is concluded that the reliability-based design method could serve as a powerful tool in the design of the open stope in connection with minimizing unplanned dilution at the Maleyevsky mine.