Stope design optimisation

Maptek stope optimisation tools handled a complex underground mine design challenge, delivering accurate results in less time than ever before.

Dundee Precious Metals (DPM) owns the Shahumyan Mine in southeastern Armenia. The complex narrow vein deposit produces gold, copper, silver and zinc from highly variable widths which range between 0.2m and 3.5m. Veins are generally closely stacked en echelon and are found in swarms and networks.

The mine resource model is updated annually for long term planning. It is necessary to review and redo stope designs in order to keep the life of mine plan current.

Updating stope shapes for the complex deposit has been a complicated and completely manual process. A quicker solution was required to allow for more rapid and timely strategic evaluations.

DPM provided the block model for testing and evaluated the Vulcan™ Stope Optimiser in collaboration with Maptek.

The resource model is particularly large given the sub-blocking regime and narrow nature of mineralisation. Once the resource model was split into manageable partitions, Stope Optimiser easily handled the model with no requirement for reblocking.

The deposit has already been partially mined out, so the mined blocks were excluded from the optimisation run. Rotated block models are no problem, nor are variations in orebody strike.

Stopes were generated using Stope Optimiser. The main challenge in modelling was due to the shape of the narrow veins, requiring multiple stope heights. In addition, suitable space must be allowed for development activity on each level, and manual post-processing is also required to remove the small number of operationally unfeasible stopes.

The final stope design was produced much faster than traditional manual methods.

Inputs to the optimisation process are saved in a specification file for future use. Varying stope heights can be input honouring the sub-level constraints. Multiple height combinations are available via panel inputs and sub-units can be defined. Varying stope widths can be based on lower and upper constraints.

Footwall and hanging wall dilution can be accounted for. Upper and lower bounds for strike and dip can be input and varied by footwall and hanging wall locations.

A standoff distance from mined or exclusion zones can be defined. Optimisation can be performed using grade or value cutoffs with single or variable values.

Once data is entered, stope shapes are automatically produced to specification, in a repeatable and optimal way. Splitting, smoothing and merging options allow users to finetune the stope shapes.

Stope Optimiser allows users to generate a stope design which delivers the expected ore grade. It increases accuracy in mineral resource conversion and minimises manual design work. Individual designs take into account stope geometry along with geological constraints.

When Stope Optimiser is implemented, DPM expects that the mine planner will be able to quickly identify the mineralised portion of the mineral resource above a cutoff while also accounting for practical mining parameters. This will allow the mine planner to confidently proceed with development plans.

Thanks to
Dundee Precious Metals