Locations (Stockpiles) may be proportionally allocated one or more Depletion Models. Typically, the models that can be selected for a location are:
- FIFO (First in First Out )
- LIFO (Last In First Out)
- Weighted Average
Computing ore parcels
When material movements are processed as part of shift processing, ore parcelsare computed. An ore parcel is defined as material flow from one location to another during a shift. Shift processing computes the inventory, tonnes and grades, at the end of each shift. The computation gives a sequence number to each parcel at a location. The sequence number is used when depleting the stockpile.
In case of a Weighted Average location, the parcels are not retained. This reduces the amount of data and speeds up processing. Unless you are certain that FIFO or LIFO is appropriate, you should use a weighted average.
If FIFO or LIFO is chosen, the ore parcels are retained until a parcel is depleted entirely. In case of LIFO, the ore parcel with the largest sequence number is depleted first. In case of FIFO, the ore parcel with the lowest sequence number is depleted first.
An orepass is a good example of a FIFO location.
Configuring depletion models
Depletion Models can be configured using Reference Data.
Code
The Code field stores the code of the location you want to assign FIFO / LIFO factors to.
Period
The Period field stores the start date from which the specified FIFO / LIFO factors become active for that location. The stockpile management method for a location can change over time.
FIFO / LIFO
The figure you set for each of the FIFO/ LIFO settings is a percentage. If the percentage you enter for FIFO / LIFO does not add up to 100%, then the remainder is treated as weighted average grade .
If you enter a value for LIFO or FIFO, you must enter both values, even if those values are zero.