Critical path management of the mining value chain using a probabilistic approach

Abstract

The mining value chain is described as a system of interacting processes impacted by variability. Variability causes schedule time slippage during execution and if not managed prevents mine plan delivery. The impact of variability on time slippage is described mathematically for simple value chains using a probabilistic approach, and extended to complex value chains using numerical and simulation modelling. The concept of Conservation of Variance is established and demonstrates the mathematical relationship between variability and time slippage. Variability injected into a value chain is preserved until rejected through time slippage. This reinforces the need to manage variability in the mine plan and during execution. This management applies three risk controls of reducing variability, buffering residual variability within buffer control limits, and mitigating residual variability beyond these limits. Synchronisation is described as a method for managing variability through these risk controls within the planning process. The value chain is described as a set of parallel production streams, each represented by a sequence of mining ‘projects’. Each production stream contains a critical path of processes to deliver valuable material. A case study is presented to demonstrate application of critical path management using an approach that integrates probabilistic mine planning and operational project management.