Evaluation of Grade Engineering using Enterprise Optimization Michael Scott, Nick Redwood
Who we are Not for Profit Research Organization Site implementation of stepchange innovation Grade Engineering Integrated Extraction Simulator Mining innovation hub www.crcore.org.au Consulting professionals Holistic business optimization service for strategic mine planning Enterprise Optimization Money Mining Workshops www.whittleconsulting.com.au
Grade Engineering Grade Engineering applies coarse separation techniques to: remove uneconomic material from ore recover economic material from waste, or exchange high-value and low-value fractions between processing destinations enhance the quality of ore processed improve material allocation decisions increase the value of the asset reduce energy, emissions and water intensity of metal production Leach/Waste Concentrator
Strategic Planning Complexities Block Model Direct Feed Waste Lower Value Heap Leach Mining Grade Engineering Stockpile Metal and material tracking Capacity constraints Upstream/downstream impacts Higher Value Processing Plant
Enterprise Optimization Increasing the value of mining and mineral processing operations through better long-term planning decisions Holistic business optimization service for strategic mine planning Links strategic decisions (and impact) across operational components Key Benefits 1. Customizable process flowsheets 2. Activity based costing 3. Theory of constraints
Project Scope Demonstrate the ability of Enterprise Optimization to incorporate and evaluate the principles of Grade Engineering Case Study Marvin deposit; hypothetical but realistic case study Three Grade Engineering techniques: Test 1. Natural deportment 2. Differential blasting 3. Bulk sorting
Natural Deportment Certain mineralizations exhibit a natural tendency to concentrate valuable minerals in finer size fractions during blasting and crushing Cut-off
Differential Blasting Differential blasting adjusts the design within a blast to achieve finer fragmentation in high-grade and coarser fragmentation in low-grade.
Bulk Sorting Ore sorting uses quantitative or indicative sensor measurements of grade to decide whether to accept or divert material at transfer points within mining and mineral processing activities. Delivered grade heterogeneity, sensor performance and separation efficiency
Case Study: the Deposit Cu-Au porphyry Higher Au grades at shallow elevation Higher Cu grade at depth Six geometallurgical processing domains Hypothetical but realistic deposit Gold Grade Copper Grade Grade Au (g/t) Cu (%)
Case Study: the Operation Open pit mining method Processing plant (SAG, ball, flotation) 4 grind sizes (tph, recovery, grinding media costs) Heap leach Stockpiles Grade Engineering Screening Plant Cross belt analyzer (post primary crusher)
Process Flowsheet Direct Feed Waste Bulk Sorting 20% Accept 40% Accept Divert Heap Leach Tails Product 60% Accept 80% Accept Accept Stockpile Block Model Screening Plant Processing Plant Mining Differential Blasting Natural Deportment 30mm Screen 50mm Screen 75mm Screen Coarse Fines SAG Mill Ball Mill 75μm Grind 100μm Grind 150μm Grind 200μm Grind Tails Product 100mm Screen Flotation 150mm Screen
Scenarios $700 $690 Differential Blasting + Bulk Sorting All Differential Blasting -> Natural Deportment -> Bulk Sorting Net Present Value (US$ Millions) $680 $670 $660 $650 $640 $630 $620 Differential Blasting Base Case + 1 Grade Engineering Technique Scenario + 2 Grade Engineering Techniques + 3 Grade Engineering Techniques Differential Blasting -> Bulk Sorting -> Natural Deportment Natural Deportment -> Bulk Sorting -> Differential Blasting Natural Deportment -> Differential Blasting -> Bulk Sorting Bulk Sorting -> Natural Deportment -> Differential Blasting Bulk Sorting -> Differential Blasting -> Natural Deportment
Operational Impact Mining rate increased Mining finished 2 yrs earlier LOM not significantly reduced Increased use of the stockpile Ore (Mt) 16.0 12.0 8.0 4.0 Processing Plant 1.00 0.80 0.60 0.40 0.20 Cu Grade (%) Au Grade (g/t) Greater proportion of finer grind/ higher recovery Processing plant closed 1 yr earlier more metal recovered Cut-off grade Increased in earlier years Decreased in later years Energy intensity of metal production decreased by 7% Ore (Mt) 0.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0 Heap Leach 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Year 0.00 0.80 0.60 0.40 0.20 0.00 Cu Grade (%) Au Grade (g/t)
Value of Grade Engineering Coarse separation: Upgraded material improves the grade processed at bottlenecks Removing low-value material from bottlenecks increases capacity to treat higher value ore Supported by: Metal Exchange low-value fractions are exchanged with high-value fractions Increased mining rate higher proportion of mined material can be Grade Engineered Stockpiles defer the treatment of lower value material
Conclusion Enterprise Optimization was successfully demonstrated as an effective methodology to evaluate Grade Engineering strategies All coarse separation techniques improved the value of the operation Benefits of each technique were not cumulative Coarse separation techniques competed for treatment of the same material Grade Engineering produced greater value by increasing the cut-off grade in earlier years; accelerating metal recovery Decreasing the cut-off grade at the end of the operation; expanding reserves and improving resource utilization Supported by increased mining rate, stockpiling and metal exchange Further details: www.crcore.org.au or www.whittleconsulting.com.au
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