AAOM Handbook

[OFFICIAL]

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Step 2: Modelling the ‘Normalized Unconstrained’ valuable mineral: The normalized Unconstrained Output column exhibits the Unconstrained Total Output converted to a common measure at that specific stage in the process. Each ‘transform’ and ‘transfer’ process modelled has a normalized Unconstrained Output. All normalized Unconstrained Outputs have the same unit to the valuable mineral and can thus be used as the common measure to compare all ‘transform’ and ‘transfer’ processes against one another, allowing for the identification of the system constraint once the model has been fully calibrated. The histograms in a common metric ‘FGO’ are overlapped with each other on a single graph as depicted in Figure 2 in chapter 2. There are two types of constraints. The type of constraints that should be identified and dealt with first are those related to excessive variation and then capacity i.e. bottleneck. Reducing the effects of this variation typically yields several times the output benefit of trying to shift the process operating point without reducing the variation. When variation has been adequately dealt with, the capacity constraints in the process should be dealt with. Hence it is critical to follow the sections below to obtain the constrained and calibrated output for holistic analysisof constraints and opportunities. Product such as copper, coal, iron ore would refer to metric such as saleable tons. Platinum would refer to ounces or and diamonds would be carats etc. • The unconstrained column needs to be multiplied by the recovery, multiplied by the grade and divide by the percentage of product in concentrate. By performing this calculation, it is possible to determine the capability of the Mine process in terms of product. If the grade is 65%, the recovery is 85% and the percentage of product in concentrate is 30%, then the normalized unconstrained product column to be calculated as shown in Figure 14. It is important to note that process efficiency losses happen at many steps of the value stream, e.g when converting resources to reserves or mine design from reserve to mineable stocks. We need to measure and model recovery losses must be measured and modelled at each relevant stage in order to better identify value adding opportunities. An example converting copper Ore into Copper Product:

Figure 14 - Normalizing the Unconstrained Mine process Note that the grade, recovery and concentrate are all inputs that the accountable person could update or change as necessary, either for testing scenarios or because the operating level has changed. The process in the value stream determines the necessary conversion steps and factors.

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