Grade Targets

Grade targets allow the user to specify a strict grade range, and place penalty multipliers on deviation from the Target.

Different Destinations may have different Grade targets.


Adding Grade Targets for Stockpiles and Crushers


Set the destination, grade field, and grade limits to apply and input targets and limits in the Calendar

Grade Fields

Grade specifications can be set to reference any field in the database:

In-situ Fields

Example Field Application Note
mining_grades_fe Insitu Grade/Head Grade Use these fields on Stockpiles and Crushers when targeting a head grade.

Process Streams Fields

Example Field Application Note
mining_ProcessStreams_dry_rail_SubProducts_fines_grades_fe Fines product grade, through the "dry" plant, at the "rail" point Use these fields to target product grades on Stockpiles.
mining_ProcessStreams_dry_rail_grades_fe Total (Lump + Fines) product grade, through the "dry" plant, at the "rail" point Since the software does not know what Crusher the Stockpile will feed into, the user is required to specify the Processing Stream of the quantity fields.

To configure the dry/wet, rail/ship, lump/fine process stream options, seeProcessing Paths.

Output Fields

Example Field Application Note
Output>rail_SubProducts_fines_grades_fe Fines product grade, through the (wildcard) plant, at the "rail" point Use these fields to target product grades through Crushers.

Since the software knows the Processing Stream for each Crusher, the “Output” fields act as a wildcard to automatically select the corresponding grade fields.

Grade Limits and Targets are explained in the table below.

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.

Blend Targets