EP 171 | Part 2 of 2: Managing Uncertainty - How Better Grade Control Leads to Better Decisions

In Part 2 of our Fresh Thinking by @SnowdenOptiro  two-part series, host Melanie Bully is joined by Senzeni Matondi to continue the discussion on why the most expensive mistake in grade control isn't necessarily mining low-grade material — it's making the wrong decision about whether material is ore or waste. Following on from Part 1, this episode explores how mining operations can make better grade control decisions by understanding and managing uncertainty. Melanie and Senzeni discuss why average grade alone doesn't tell the full story, how conditional bias and grade smoothing can affect ore and waste classification, and why local accuracy around the cut-off grade is so important. They also explore grade control as a complete value chain — from sampling, QA/QC and geological logging through to estimation, dig planning, mining execution, stockpile management and mine-to-mill reconciliation. The conversation then turns to modern approaches to uncertainty and risk, including conditional simulation, probability-based ore classification and risk-based digline optimisation. In this episode Melanie and Senzeni discuss: Why two models with similar average grades can deliver very different operational outcomes Conditional bias and the impact of grade smoothing The importance of local accuracy around the cut-off grade How ore loss and dilution result from misclassification • Why reconciliation reflects the performance of the entire grade control system Moving from deterministic estimates to risk-informed decision-making What best-practice grade control looks like at high-performing operations The key message from this two-part series is simple: grade control isn't about producing the perfect block model — it's about consistently making better mining decisions.