Grade
On the Grade tab of the Stope Design and Generation form, configure the extractions identified by the optimiser included in stopes.
Exclude all slices with values below
(Optional.) Enter the minimum optimisation value for slices to be included in stopes. If this field is left blank, no restriction will be applied.
Slices with optimisation values below this number will not be included in stopes and will be consigned to the separations between the identified stopes.
Applying this constraint is likely to reduce the total value of the extractions identified by the optimiser.
Head Grade Optimisation Options
(These options are enabled when the Optimisation Value parameter is set to Use head grade on the Stope Optimiser > Mine > Definition > Model > Block Model page of the Mine Setup form.)
These settings affect the slices that may be included in stopes and where those slices may be placed within the identified stopes. Applying any of these settings is likely to reduce the total value of the extractions identified by the optimiser.
Waste cutoff
Specify the grade below which material is considered to be waste. The default ([Auto]) indicates that the head grade should be used for this purpose.
Allow waste at
These options control whether waste material may be included as required on the ends of the stopes to satisfy design requirements. However, you will also need to consider how those decisions might impact the inclusion of the “planned” dilution as specified by the Near Dilution and Far Dilution fields.
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Near end. Select this option to indicate that slices with optimisation values between Exclude all slices with values below and Waste cutoff may also be included at the near ends of the stopes.
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Far end. Select this option to indicate that slices with optimisation values between Exclude all slices with values below and Waste cutoff may also be included at the far ends of the stopes.
If you have chosen to allow waste at the near end and/or the far end of stopes, choose whether dilution will be added to the stope ends:
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To maximise contained metal, or
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Only to satisfy minimum stope length
Reject stopes with mineable waste
Select this option to indicate that stopes with mineable portions of waste (i.e. sub-stopes with head grades below Waste cutoff) should be prevented from being included in the set of stopes identified by the optimiser.
This option prevents seemingly readily identified waste portions from being included in stopes. Although this sounds like a good idea, the option should be used with care because it may prevent the optimiser from selecting some stopes that would otherwise satisfy the design criteria for size and head grade.
In effect, the option changes the behaviour of the optimiser from (1) maximising the mass of potential ore that is made available for processing, to (2) excluding all of the perceived waste and then maximising the mass of potential ore that is made available for processing from the remainder. The disadvantage of this approach is that it restricts the optimiser's ability to mix low grade ore with higher grade ore to create a larger combined mass with a (head) grade that would still be suitable for processing.
On the Grade tab of the Underground Design > Stopes (Tubes and Slices Method) form, additional options for optimising for head grade have been added.
Note: These settings are enabled when the Optimisation Value parameter is set to Use head grade on the Stope Optimiser > Mine > Definition > Model > Block Model page of the Mine Setup form.