Sink Rate
The Sink Rate is the mining duration per bench. It is determined based on the total tonnes available for mining on a bench and the corresponding dig rate. This information is provided using the Sink Rate constraint user interface.
The sink rate constraint is a hard constraint
Evolution must obey this constraint when generating a schedule..
This constraint allows for variable dig or production rates based on your definitions. For example, a bench may have just enough area and therefore tonnes for 1 dig unit. You will define this and reference a dig rate for the single unit. However, if the tonnes on a bench are more than this specified range, Strategy will check the constraint set up and use the appropriate mining rate defined by the larger bench tonnage.
You can also specify if the constraint is applied globally or not by ticking the Global Sink Rate checkbox. When the checkbox is selected, the total duration for mining all benches in all stages in a single period cannot be more than that period. If the checkbox is unselected, the total duration of all benches mined in a particular stage cannot be more than a period (year).
When using the Sink Rates constraint, Evolution calculates the end of period (1 year) by utilising the rates entered by the user.
Evolution analyses the available tonnes on a particular bench and cross references the rates entered. It then divides the tonnes on the bench by the given rate (tonnes/year) for the corresponding range. This result creates a fraction, which represents the amount of a year it takes to mine that particular bench. Evolution continues this process whilst adding these fractions together until the total is equal to one (or one year).
Using the example above, if there were 6,000,000 tonnes on a bench, then the 12,000,000 rate would apply:
6,000,000 / 12,000,000 = 0.5
Therefore it would take half a year to mine one bench and one year to mine 2.
If no other constraints are required, the Strategic setup is now ready to be saved and validated before being scheduled.
Sink rates can also be defined per stage using the Stage Sink Rate constraint. If the global checkbox is selected, the sum of all stages cannot be more than one.