Many technical planning staff and executive decision makers in the mining industry do not realize how critical the selection of cut-off grades is to their company’s success. The goals implicit in the cut-off derivation are the de facto company’s goals, regardless of what the chairman or president might tell the shareholders! Yet commonly used cut-offs derived by break-even calculations are virtually guaranteed to not maximize, for example, profits or net cash flow measures. 

This “executive summary” course is designed to remove the mystique surrounding cut-off grades. It initially describes increasingly complex cut-off models that progressively account for costs and prices (break-even cut-offs stop here!), the grade distribution of the resource, and the capacities and capabilities of the mining equipment and treatment plants. It then demonstrates how the optimum cut-off policy and all other key value-driving decisions should together be based on the results of a comprehensive evaluation focussed on delivering the company’s and other stakeholders’ goals. Counter-intuitive to many is the common discovery that optimum cut-offs are often unaffected by cost and price assumptions or changes and may vary over time and from place to place within the deposit. Cut-offs are an output from the planning process, not a predetermined input into it. 

The techniques described also identify robust plans that manage the trade-offs between upside rewards and downside risks if the assumptions underlying the plan turn out to be wrong, as they inevitably will be! Misconceptions and objections are discussed and results from case studies presented.  

Short Course Objectives: 

The techniques described also identify robust plans that manage the trade-offs between upside rewards and downside risks if the assumptions underlying the plan turn out to be wrong, as they inevitably will be! Misconceptions and objections are discussed and results from case studies presented. 

Target Audience: 

Mining Engineers, Geologists, Processing Engineers 

About the Instructor:  

Brian Hall is a mining engineer with over 50 years’ experience in the mining industry. The first 20 years of his career were largely spent in mostly planning but also operating roles at large underground base metals operations in Australia and South Africa. The last 30 years have been with AMC Consultants in Australia, where he has worked on both open pit and underground projects around the world. Over the last 25 years he has developed a reputation as an expert in cut-off grade and mine strategy optimization and authored the 300-page text “Cut-off Grades and Optimising the Strategic Mine Plan”, published by The AusIMM in 2014.