Stockpile Algorithm Modelling
Reconcilor supports multiple algorithms to model stockpiles and predict the grades of reclaimed material. Choosing the correct algorithm ensures that grade predictions accurately reflect how stockpiles are built and reclaimed at your site.
In most cases, simple algorithms such as Average or FIFO provide the best results. However, some operations—such as ore passes, ROM fingers, or stockpiles with specific build strategies—may benefit from more advanced options.
Reconcilor supports the following grade modelling algorithms:
• Average (default)
• First In First Out (FIFO)
• Last In First Out (LIFO)
• LIFO Average
• LIFO Configured
Important: Select the algorithm that best represents your site’s real-world stockpile management practices.
Average (Default)
The Average algorithm assumes that all material within a stockpile is evenly blended. Individual parcels of material are not tracked, and composition is not calculated.
When material is reclaimed:
- It is assigned the average grade of the stockpile at that time.
- If an Average-modelled stockpile delivers material to a stockpile using another algorithm, that material will be recorded as Unknown grade.
Tip: Best used for stockpiles where blending is consistent and parcel tracking is not required.
First In First Out (FIFO)
The FIFO algorithm models material flow such that the first material delivered is the first material reclaimed. It depends on the order and accuracy of transactions to and from the stockpile. As material is reclaimed, it takes on the grade of the oldest parcels remaining in the stockpile.
Example: FIFO Algorithm
| Step | Action | Stockpile Contents (tonnes) | Notes |
|---|---|---|---|
| 1 |
Opening balance |
A 100, B 5 |
|
| 2 |
Add 100 t of Block C |
A 100, B 50, C 100 |
|
| 3 |
Remove 50 t (Block A) |
A 50, B 50, C 100 |
Removes oldest material first |
| 4 |
Add 100 t of Block A |
A 50, B 50, C 100, A 100 |
Adds new parcel |
At the end of the shift, the mass-weighted average of the remaining components is used to calculate the stockpile’s grade balance.
Tip: FIFO is suited to stockpiles reclaimed in the same order they are built.
Last In First Out (LIFO)
The LIFO algorithm models material flow such that the last material delivered is the first material reclaimed. It also relies on accurate sequencing of stockpile transactions. As material is reclaimed, it takes on the grade of the most recently added parcels.
Example: LIFO Algorithm
|
Step |
Action |
Stockpile Contents (tonnes) |
Notes |
|---|---|---|---|
|
1 |
Opening balance |
A 100, B 50 |
|
|
2 |
Add 100 t of Block C |
A 100, B 50, C 100 |
|
|
3 |
Remove 50 t (Block C) |
A 100, B 50, C 50 |
Removes newest material first |
|
4 |
Add 100 t of Block A |
A 100, B 50, C 50, A 100 |
Adds new parcel |
At the end of the shift, the mass-weighted average of all remaining parcels determines the stockpile’s grade balance.
Tip: LIFO is ideal for ROM fingers or ore passes where reclaim follows a “last in, first out” pattern.
LIFO Average
The LIFO Average algorithm applies the LIFO model to grades for the most recent shift, then reverts to average weighting for subsequent shifts. This approach smooths short-term grade fluctuations while maintaining realistic reclaim behaviour.
LIFO Configured
The LIFO Configured algorithm applies LIFO modelling for a defined period (in days), after which it reverts to the Average algorithm.
The configured period should match your site’s stockpile activity frequency.
Tip: Set the configured period longer than the interval between additions. For example, if material is added every two days, configure LIFO Configured > 2 days to prevent incorrect depletion grade calculations.
Behaviour and Calculation Rules
Negative balances – Reclaim grades will always be NULL if the closing balance for that shift is negative — even if deliveries during the same shift match or exceed the reclaimed tonnes. Example: If a stockpile opens at –5000 t, receives 3000 t, and reclaims 2000 t, the reclaim grade will be NULL because the closing balance is –4000 t.
Deliveries with NULL grades – If a delivery with NULL grades is received, that parcel is automatically assigned the current weighted average grade of the stockpile. When later reclaimed, the movement grade will be based on this previously assigned weighted average.
Summary
Stockpile algorithm modelling allows Reconcilor to simulate how material is added to and reclaimed from stockpiles. Selecting the algorithm that best matches your site’s operational practices ensures that grades, tonnes, and balances reflect real-world behaviour — improving reconciliation accuracy and confidence in reported results.
