MSO Block Models

A block model in MSO serves as the foundation for stope optimization. It defines the input block model, economic and physical parameters used during optimization, and critical filtering logic.

The Block Model controls which block model data is included in the analysis and how material types and reporting attributes are handled. This functionality is essential for tailoring the optimization to site-specific conditions such as multi-vein orebodies, complex zoning, and reporting requirements.

A block model must be specified in order to continue with the optimization scenario.

Note: MSO is not applicable for regularised block-models that use a percentage-populated field for contained metal (grade) or value (dollars). These models however can be converted by over-printing cells filled within the mineralization wireframe(s) over the regularised model to create a sub-celled model. The cell size and the level of sub-celling used in the block model will determine the precision of the orebody representation.

See MSO Block Models.

See MSO Materials.

MSO Block Model Guidelines

Consider the following when configuring a block model for an MSO run:

  • An input model can be regular or subcelled, and can be rotated.

  • Check the model to ensure that missing or absent data is identified and appropriate defaults are set. A default of zero for a value field is probably not appropriate because the missing blocks or values are probably intended to be treated as waste (e.g. have negative values due to processing cost). Flag areas in the model where stopes should not be optimised e.g. near the surface, close to infrastructure or in poor geotechnical ground. Use model fields like oretype or resource category to allow later classification of stopes.

  • Processing a model with waste cells adds a significant overhead, but this is necessary if creating full-stopes and sub-stopes. Remove barren waste cells from the input model if only full-stopes are required.

  • Models should ideally have an enclosing envelope of waste cells modelled around the mineralization. The surrounding waste is required for cases where a sub-stope may be mined adjacent to a full stope using waste pillar criteria (an MSO requirement). If sub-stopes are not required, then non-mineralized waste cells can be filtered from the block model to reduce run times.

  • Models should ideally avoid absent data (’-‘), especially for the DENSITY field, the cut-off evaluation field or any other reported field(s). For the situation where cells have “absent” values or where cells are missing from within the stope shape, the default value supplied for each field is applied. Careful consideration is required regarding the default values selected, especially regarding the optimization field.

    For example, if the optimization field is a metal grade field then zero may be appropriate, but if the optimization field is a value field (for example, the net smelter return dollar value) then a negative number representing the cost to mine (and process) waste may be more appropriate than a zero value.

  • The block model cell size should ideally correlate with the definition of the mineralized zone such that several cells define the stope width (XZ/YZ strike orientation) or stope height (XY/YX plan orientation). One or two cells representing the stope width and height would generally be too coarse to represent the orebody grade distribution.

  • The model must have definitions for the size and number of cells, origin and optional rotation (if applicable) and be able to be expressed with the Datamine Studio model definition conventions.

  • The model definitions used internally by MSO are the set of fields [IJK, XC, YC, ZC, XINC, YINC, ZINC, NX, NY, NZ, XMORIG, YMORIG, and ZMORIG], which coincide nicely with the default fields generated for a Datamine block model.

  • For rotated models, the optional rotation fields [X0, Y0, Z0, ANGLE1, ANGLE2, ANGLE3, ROTAXIS1, ROTAXIS2, and ROTAXIS3] are also used internally by MSO. The rotation point [X0, Y0, Z0] used is at the origin of the model. Again, these model fields are generated by default using Datamine products.

Summary

This part of the MSO workflow is used to:

  • Select the input block model.

  • Define economic fields, density, reporting attributes, and material exclusions.

  • Apply bounding solids if needed.