A short post to remind mine planning engineers that grade is just a proxy for value. You need to prove to yourself that it is a good proxy to use. Years ago, I used to present a value creation and #CutOffGrade seminar. I would start the seminar with the following three questions as a thinking exercise: Q1: Consider two blocks of ore (everything else being equal), which block has higher value: (a) 100 tonnes @ 2.0% Cu. (b) 100 tonnes @ 2.5% Cu. The obvious answer would be (b), as it contains 2.5 tonnes of copper, versus (a) with 2.0 tonnes of contained copper Q2: Consider the same two blocks of ore, but now with recovery information (and again everything else being equal), which block has higher value:: (a) 100 tonnes @ 2.0% Cu - with 80% recovery. (b) 100 tonnes @ 2.5% Cu – with 85% recovery. Again, the obvious answer would be (b), as it has 2.1 tonnes of recovered copper versus (a) with 1.6 tonnes of recovered copper. Q3: Now consider the same two blocks of ore, with recovery information and throughput information (and again everything else being equal), which block has higher value: (a) 100 tonnes @ 2.0% Cu - with 80% recovery, and SAG mill throughput of 100 tph (so soft ore, and/ore well fragmented). (b) 100 tonnes @ 2.5% Cu – with 85% recovery, and SAG mill throughput of 70 tph (so hard ore, and/or poorly fragmented). Now, the answer flips to (a), as (a) has a recovered copper per hour ‘value’ of 1.6 tonnes Cu per hour, and (b) has a ‘value’ of 1.49 tonnes Cu per hour. So, in this third situation, the lower grade, lower recovery ore provides 7% greater ‘value’ in time – and it is what we produce in time that ultimately determines the value (NPV is after-all a measure of ‘$s in time’). This leads to the ‘cash flow grade’ concept, quite well described by Dr Brett King in a paper he write back in 1999. (I loved this paper when I first read it, as I was ~90% there myself - and felt frustration that Brett had written it first!) The concept also leads to the necessary identification of system bottlenecks that need to be exploited (#TheoryOfConstraints) to increase the ‘value flow’. These concepts are effectively what Gerald Whittle has effectively based his business on: the cash flow grade concept – combined with TOC – and using software to solve complex systems that can result. So – grade is just a proxy for value. Sometimes it can be a good proxy. Other times it can be a poor proxy. I have only ever once seen a feasibility study use a cash flow grade for the mine schedule. And I will be first to acknowledge it is not an easy thing to use. It can’t be directly measured like a grade. It must be calculated from multiple factors – of which grade is just one factor. And we usually often don’t have reliable models for those other relevant factors. My advice: do as much economic value modelling of your ore value as you can, and find some approach to cut-off value that is practical and makes sense, AND captures some of that time value. References King, B. 1999, “Cash Flow Grades - Scheduling Rocks with Different Throughput Characteristics”, Proc. Conf. Optimising with Whittle, Perth 1999.

Reviewing mining projects from discovery through to operations, there’s one issue that comes up time and time again: resource classification. Teams spend countless hours on estimation methods and geological interpretation, only to fall short when it comes to correctly classifying the resource. Why does it happen? Optimism bias (often driven by board or funding expectations) Time pressure at the end of a study Inexperience with classification standards Or simply underestimating how critical classification really is As an external reviewer, here are a few practical principles that consistently separate robust resource models from risky ones: 🔹 Let drill spacing lead the classification Be strict. If there are spacing gaps, classify them accordingly. No “spotted dogs”. 🔹 Avoid circles around drill holes Resources aren’t radial. Use orebody knowledge and geological controls to define realistic shapes. 🔹 Data integrity matters QAQC results, core recovery, and missing samples must be reflected in the classification. Confidence in tonnes starts with confidence in data. 🔹 Respect the limits of your estimation parameters Search radii, variography, and interpolation choices should cap — not inflate — classification confidence. 🔹 Classify waste properly If the drill spacing supports a measured ore classification, the same logic applies to internal waste. Mining companies want to know where measured waste is — ironically, we mine far more waste than ore. Resource classification isn’t a tick-box exercise. It’s a risk statement, and decision-makers rely on it more than we often acknowledge. Get it right early, and everything downstream — mine design, scheduling, economics — becomes stronger. Happy to discuss or hear how others approach this challenge in their projects.

Géologie, Exploration, Exploitation et Traitement, Lungu Maina Le tantale, le tungstène et l'étain ne sont pas seulement des minéraux... ce sont les fondations invisibles de la technologie moderne. 📱 Dans vos smartphones ✈️ Dans les avions 🔧 Dans les équipements médicaux ⚡ Dans les technologies de pointe Pourtant, leur extraction et leur traitement restent complexes et controversés. Entre défis géologiques, enjeux environnementaux et problématiques de minéraux de conflit, l'industrie minière doit se réinventer. J'ai préparé une présentation complète sur : ✓ La géologie et les gisements mondiaux ✓ Les méthodes d'exploration et d'exploitation ✓ Les processus de traitement avancés ✓ Les perspectives durables de l'industrie La géologie minière n'est pas seulement une science, c'est une responsabilité envers les générations futures. 🌱Intéressé par les ressources naturelles et l'industrie minière ? Partagez vos perspectives ! #Géologie #Minéraux3T #Tantale #Tungstène #Étain #IndustrieMinière #MineraisDeConflit #Technologie #DéveloppementDurable

🎬 What is Mining Engineering? Dive into the world beneath our feet and discover how Mining Engineering transforms raw geology into the materials that power our lives. From exploration and extraction to processing, safety and sustainability — this animation walks you through the full engineering journey of modern mining operations. 🔍 In this video, you’ll learn: The key roles of a Mining Engineer — geologist, planner, technician, environmental steward. How mines are designed, operated, and rehabilitated responsibly. Why safety, technology and sustainable practices are central to the discipline. How this field connects with energy, infrastructure, communities and global resources. The future‑shaping skills and opportunities in Mining Engineering today. 🌍 Whether you’re a student exploring career options, a professional in the industry seeking a refresher, or simply curious about how the things around us really get made — this animation distills complex engineering into clear, engaging visuals and insights. 👉 Tap the link to watch the full animation and join the conversation on Zvenia. Let’s explore the layers of Earth — and the layers of innovation — together.