Scheduling Setup: Options

Stockpile type allows selecting between Warehouse Stockpiles and Mixed Stockpiles.

• Warehouse Stockpiles compute faster and are suitable for projects with large number of periods. With this option a stockpiled block is considered available to be reclaimed with its own grades without mixing with other stockpiled blocks.

  • Maximum periods to reclaim – Set the maximum number of periods a block can be stockpiled before being reclaimed.

• With Mixed Stockpiles, the grade of a stockpile is the weighted average of the blocks sent to the stockpile.

  Note: Using mixed stockpiles may increase the computation time. When this is a problem you should consider using the warehouse type.

Note: The Optimizer requires mixed stockpiles with initial tonnage to be empty at the end of the schedule. In rare cases when using mixed stockpiles with large initial tonnage, not enough periods to reclaim, or a low reclaim rate (processing capacity) the Optimizer will show the message "Problem has no solution". This can be avoided by adding more periods or decreasing the initial tonnage.

See Mixed & Warehouse Modes.

A Multipass heuristic will be used when the periods to optimize are greater than the user defined value (between 30 and 60). The default optimizer setting is to solve submitted problems globally to within a guaranteed optimality tolerance. The optimizer can be configured to run a “multipass” heuristic to obtain a solution, rather than to attempt to solve the problem globally.

Note: The principle of a multipass heuristic is to break up the problem into smaller problems, and to use these to obtain a feasible solution to the global problem, though at the cost of an optimality guarantee.

• Check Mine All to schedule all blocks even if they have negative contribution to the Net Present Value.

• If Mine All is unchecked, Maroma will not schedule these blocks potentially leaving some benches or a whole pushback unmined.

Solver timeout is useful when optimization runs take long time to complete. The default value 1440 minutes (24 hours) may need to be reduced if runs are expected to last long.

When the timeout limit has been reached and there is a sub-optimal solution found the results are displayed. Otherwise the message "Problem has no solution" displays.

Maroma can utilize multiple cores when obtaining an optimal solution. The Number of cores is set to four by default. Utilizing more cores may help finding a solution faster, but will use more system resources.

Note: Results obtained when processing with multiple cores compared to a single core may vary very slightly (Profit, NPV, Process Cost and Revenue).

See Scheduling Setup.