Greg Shapland, CRC ORE IES – Utilisation Manager, explains that CRC ORE’s Integrated Extraction Simulator (IES) is being used to help identify the throughput boost from Grade Engineering® for the San Cristobal mine. Sumitomo is using IES to help determine the most valuable strategy for the operation.

Grade Engineering is focussed on improving the quality of feed to mills through the early rejection of gangue. The most mature Grade Engineering technique is to exploit a natural or induced deportment of grade across particle sizes, typically with higher grade in the finer particles. The result is Grade Engineered ore that is higher in metal content and finer than ROM ore.

The study site typically processes a blend of hard and soft ore in a fixed ratio. Following grade by size test work, an opportunity arose that centred on Grade Engineering, working with the hard ore and continuing to blend with soft ore in the fixed ratio. IES’ mass simulation functionality was ideal for simulating different scenarios and determining the resulting throughput and grind size.

First the site’s baseline flowsheet was augmented to include models for Grade Engineering blasting and screens. Second, a spreadsheet was populated with scenario variables including blast intensity, screen size and % of hard ore to be Grade Engineered. Extra columns were added to include formulae to determine the % throughput improvement compared to the baseline. Lastly, the IES mass simulation tool was used to upload the spreadsheet, process the simulations and write the results back to the spreadsheet.

The study found the potential for significant improvements to throughput under some Grade Engineering strategies. When combined with Grade by Size test work and the mine plan, the results provided the strong basis for subsequent analysis of overall value generation.