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Table of Contents

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Item

Description

Example

Specify Min

Limits minimum ratio of the material fed from the Source to the Destination.

Note

Crusher feed will be zero if it cannot satisfy a Minimum blend ratio. Make sure there is material available before setting a minimum feed ratio. 

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Specify Max

Limits maximum ratio of the material fed from the Source to the Destination.

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  • Minimum and Maximum are hard limits, “Actual” values cannot be outside of these boundaries.

    • If Minimum limit cannot be satisfied, the optimiser returns zero.

    • If Maximum limit is reached, no more material can be sent to the specified destination.

  • Note that when setting ratios for multiple plant components, their “Actual” values must add up to 1.

Specify Target

Specifying target also introduces “Content Deviation Penalty” input row in the Calendar.

The difference between the Actual and the Target blend is subject to this Penalty multiplier specified by the user.

The Penalty is summed with the Cash Flows to determine the reward or cost of blending materials into each Destination.

The higher the deviation penalty, the better the optimizer will try to meet the target, but it may not be achieved due to other cash flows and objectives.

Show Tram Lines

Displaying additional guidance rows for the optimisation rule in the Calendar.

Used for visual purposes only to change the color of values in the “Actuals” field, i.e. if it goes out of range by more than 0.0001 it goes red, less than orange, otherwise it's black.

Numerator and Denominator

Blend ratios are calculated using a Numerator and Denominator, as such the setup requires both to be populated.

Note

Never configure the Denominator in a way that could return a zero. If the ratio returns a "divide by zero", then crusher feed will be zero.

Destinations

The Destination(s) to which the blend target is applied.

Quantity Field

The field to which the blend target is applied.

Tip

As a general rule, the Numerator and Denominator should use the same units (either dry tonnes for the strict ratio, or wet tonnes for the weightometer ratio).

Sources

The Source(s) for Numerator and Denominator to which the blend target is applied.

View Database

Use the View Database button to open the Choose Records window, where you can graphically select and review the Sources.

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Input

Description

Notes

Grade Lower Limit

The final weighted average grade cannot be below this value.

  • Individual feed blocks can be lower than the minimum.

  • If multiple destinations are listed, individual destinations can be lower than the minimum.

Grade Limits applied to Product Specifications > StockpileGradeTarget are the weight average of the material added to the Stockpile over a Period. They are not equal to the grades of the stockpile closing balance.

Grade Upper Limit

The final weighted average grade cannot be above this value.

  • Individual feed blocks can be higher than the maximum.

  • If multiple destinations are listed, individual destinations can be higher than the maximum.

Grade Target

The difference between the Actual grade and the Target grade is subject to a penalty multiplier specified by the user.

Net grade penalty = |(Content Deviation Penalty) * (actual grade - target grade) * 100 * (total tonnes)|

The result of this formula is an absolute (always positive) value.

If Crusher A and Crusher B have different grade targets, then a single block will incur a different penalty depending on the destination. This penalty is summed with the Cash Flows to determine the reward or cost of blending materials into each destination.

Content Deviation Penalties

The value of the content deviation penalty should be considered relative to other grades, and relative to the Cash Flow values.

  • If the net grade penalty is greater than the crusher cash flow, then the crusher won't feed.

  • If the Fe grade penalty is greater than the Al grade penalty, then the optimiser may blow out Alumina to keep Iron on spec. This is because the penalty of dirtying Al is lower than the penalty of dirtying Fe.

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