Project Details

Project Details:

Caving has a very different risk profile than open pit mining and other underground methods with one of the critical areas being ROM grades that are delivered to the mill.  Though caving can match pits in terms of operating cost per tonne, it suffers from limited grade selectivity with ROM grades trending toward the orebody average due to consequences of mixing in cave columns.  Research and subsequent operational trials have demonstrated that bulk sorting can manage this lack of selectivity by “pre-concentrating” the ROM ore, providing the mill with a more consistent and higher grade feed.

The potential for bulk sorting is dependent on the heterogeneity of the ore and the ability of sensors to detect the heterogeneity. Sorting system design involves the integration of sensors into the material handling equipment to allow classification and diversion of the material for downstream handling and processing between the mine and the concentrator. The system design can then be evaluated based on operational objectives such as overall mine productivity, energy savings and profitability.

Figure 1. Simplified flowsheet of the mine and sorting systems (Nadolski et al, 2017)

The main objective of this project is to develop approaches to evaluate sensor-based sorting systems for cave mines.  The research builds off previous investigations at the New Afton Mine (BC, Canada) where in-situ heterogeneity was characterized from drill core data and related to heterogeneity at the draw points. Heterogeneity characterization includes assessing grade distributions and determining metal distribution and grade versus mass relationships. An example of outcomes from heterogeneity analyses of in situ material intersecting a cave footprint is shown in Figure 2.

Figure 2. Recovery and grade versus mass pull curves based on drill core data (Erdenebat, 2017)

The research will also focus on developing methods to measure the variation in metal content that is delivered from drawpoints through the use of sensors at various points in the ore flow system. The work will be used to assess the practical implementation of sensing systems in cave mines for real-time ore and waste diversion. Figure 3 shows the key components of a sorting analysis that are addressed by this project scope.

Figure 3. Components of sortability analysis