Scheduling in Scheduler
Material Movement Constraints
To have smooth equipment utilization, or to ramp up production on a new project or expansion you can use the material movement constraints. This lets you constrain the minimum and/or maximum total material movement for any time period. If you wish to be more specific and drop down to the level of material movement from individual pits, it is simply a matter of typing in minimum and/or maximum movements for individual pits in given time periods. This enables you to force mining from certain pits at certain times or to prevent mining in certain areas. Although this may not be optimal from a purely financial point of view, it gives you the control to represent issues which may not be entirely financially quantifiable.
Processing Constraints
Processing constraints allow you to model capacity constraints of processing nodes in your material flow. In the simple case this would be a milling process, but can be more complex to control down-stream processes such as metal refining, beneficiation, and final product shipment (e.g. rail or truck).
Series and Parallel Material Flow
Any number of processing constraints can be applied. For each process defined, when you go through the mine configuration wizard, you have the option of controlling the minimum and maximum amount of that process in any time period. If all of your processes are in series, then all material will flow through all processes. However, your mine may be configured such that a certain process (e.g. beneficiation) is an optional route. This can easily be modeled and controlled as a parallel process.
Blending Constraints
Blending constraints have been at the core of Minemax Scheduler since its inception. Blending can be in terms of ore type, grades or anything else you wish to model as an attribute. You can specify upper and lower bounds on any attribute or ratio of attributes, and have any number of blending constraints active. Unlike some other scheduling packages, Minemax Scheduler can treat blending constraints as hard constraints instead of just as preferences.
Pit Precedences with Bench Lag
Pit precedences are set at the click of a button. You can specify that a pit cannot be mined until all of another pit has been mined out. Alternatively, if your pits represent a series of stages within a larger pit you can say that a pit is preceded by another pit by a certain minimum and/or maximum bench lag.
Maximum Number of Active Pits
If you have a relatively large number of mining areas and wish to reduce the movement of equipment across these areas, you can use the Maximum Number of Active Pits constraint. For example, some of the lateritic deposits may have 30, 40 or many more possible mining areas which are all relatively small. With the Maximum Number of Active Pits constraint, you could restrict mining to at most 6 areas in each time period. This constraint leads to schedules that are optimal in the context of practicality.
Seam Precedence Constraints
With a gridded seam model, you can control mining by specifying the distance an upper seam must advance before mining begins at a lower seam. This seam precedence constraint is applied on a block by block basis for advance in the east-west and/or north-south directions.
Maximum Bench Turnover
To produce practical schedules, the maximum bench turnover constraint can be used to constrain the vertical advance per pit per time period.
Block Dependent Mining and Processing Costs
In the financial model, if you have the information available, you can specify block dependent mining and processing costs. The variability in mining cost may be due to the location of the block (deeper in the pit or further from the crusher is more expensive) whereas often the processing cost depends on the grade of the block. Mining and processing cost are actually introduced as attributes in the model to accurately model them on a block by block basis.
