Geomin Conference 2017

Event: GEOMIN 2017

Date: 23 August 2017

Location: Santiago, Chile

Paper: Evaluation of Grade Engineering® using the Enterprise Optimisation Framework



Evaluation of Grade Engineering® using the Enterprise Optimisation Framework


Grade Engineering




Dr Michael Scott1, Nick Redwood2




1.         CRC ORE
2.         Whittle Consulting Pty Ltd



Abstract text:

Grade Engineering® involves the use of coarse-separation techniques to remove uneconomic material prior to energy, water and cost-intensive mineral processing activities.  Evaluation of Grade Engineering techniques include the characterisation of coarse-separation responses within the deposit, identification of value maximising strategies for operation and the development of a business case within existing and re-optimised strategic mine plans.

The Enterprise Optimisation framework applies advanced business modelling and optimisation techniques to make strategic decisions for all elements of the mining and mineral processing value chain to produce an optimal holistic solution for strategic mine planning.

This paper demonstrates the evaluation of three Grade Engineering techniques using the Enterprise Optimisation framework at a hypothetical, but realistic case study.

The implementation of all Grade Engineering techniques yielded a net improvement of 9.9% in NPV over the optimised Base Case.  However, the value realised by adding multiple Grade Engineering techniques to an operation is not cumulative due to competition for the same material.

The results show that when the operation is not limited by the quality and quantity of ore being mined, the separation of lower and higher-value streams using Grade Engineering will raise the head grade to the processing facilities and accelerate the rate at which metal is recovered.  This generally occurs early in the life of a mine when discounted cash flows have a higher weighting on NPV. At the end of the mine’s life, Grade Engineering allows the economic processing of the higher-value component of low-grade material that would otherwise be classified as waste. Therefore, the minimum economic cut-off grade is ultimately lower in a mine with Grade Engineering and ore reserves and resource utilisation are higher.




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