It is important for mine planners to report numbers that are as accurate as possible when generating mining schedules. GEOVIA MineSched, as a planning software of choice, provides the user with an option to increase the level of accuracy in the volumes and tonnages through the partial percentages option when reporting quantities in either solids or polygons.
Why use partial percentage?
The use of partial percentage option is significant and necessary when working with massive deposits (e.g. igneous pipe deposits such as diamonds and copper) where the block sizes in the block model are fairly big, i.e. above 5m on the Northing and Easting. The below figure shows an open pit block of 25m by 50m with a mining polygon drawn in red.
In the above figure, the evaluation of the mining block as a location, with no partial percentages specified, will yield a volume of 25m x 50m x 10m = 12,500 cubic meters (assuming a 10m bench height).
This is because the centroid of the block model block is inside the mining block. This leads to an overestimation of what is available for mining. The reverse is true when the centroid is sitting outside the mining block, there will be underestimation of material available material (Figure 2)
The partial percentage creates additional ‘centroids’ by sub dividing the bigger block model block into smaller blocks using varying Precision (values 1 to 5 depending on level of accuracy needed and computer specs)
How do we resolve these challenges?
- In order to address the challenge specified above, you can select partial percentages and specify the level of accuracy. The partial percentage can be set on a Polygon, a Solid or a specific Constraint.
- Below is a mining block evaluated as a location with varying Partial Precision.Fig. 2: Mining block viewed in Minesched Graphical Sequencer
- The block in Figure 2 was evaluated using different levels of Precision and the values may be seen below on Figure 3, below.
It is clearly evident from the figure above that without the partial percentages; there is an underestimation of the material available for mining in the block.
Note that the user can decide which precision value is appropriate for their data depending on the variation obtained from change in precision values from 1, 2 through to 5. The higher the precision value, the longer it takes to evaluate the locations.