Our experience is that the mining process is inherently more variable than manufacturing; there are more environmental surprises, and the history of what happened in the previous production cycle can affect how well a department performs in this cycle. Interdependency is high. These considerations make Lean implementations harder (excluding those focussing on the processing plant), especially when attempts are made to optimise the performance of all departments in a balanced capacity chain. When optimising all parts of a balanced capacity chain, the interdependency and high variability result in significantly lower output than expected. This forces management to redouble efforts to meet operational targets, and it is not surprising that we find mining managers the busiest executives in any of the industries we deal with. The Theory of Constraints holds that the slowest steps in the production system control the performance of a production system. Usually, there is only one slowest step or bottleneck. This knowledge enables managers to focus their attention and efforts on the "bottleneck" and deliver leveraged production increase (Goldratt maintained that the essence of TOC is "FOCUS"). The famous "3 bottles experiment" video from my colleague, the late Arrie van Niekerk, demonstrates the effect of focusing on flow through the bottleneck on mining performance. Note how changing the rules of operation provide the first jump in performance, but that the most significant benefit arises when we also address the people side of the organisation.
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