Ore Misallocation: How Misrouted Ore Impacts Recovery

At NTWIST, we've witnessed it on site more times than we can count: a truck with a portion of a valuable parcel of ore is dumped on the wrong stockpile. Whether misrouted from blast misalignment, miscommunication, or static classification, the value of the ore is wasted on a pile that will never reach the mill. Every time high-grade ore is dumped in an unaccounting or low-grade pile, not only are you introducing inefficiency, but you've permanently diminished mill performance. In this article we'll discuss how ore ends up misallocated, the cost to your recovery, and how smart routing can reclaim that value for your mine.

How Ore Gets Misallocated

Ore misallocation is when material is put onto a stockpile that doesn't represent its true value or characteristics. This can occur for many different reasons, some of the most common include:

Uncorrected blast movement

If the blast moves material from one block to another, the blocks can be dug in the wrong order or without accounting for in situ movement.

Overgeneralized dig blocks

If classification bins are too broad, they don't account for the variability within the blocks.

Static routing rules

The routing logic for hauling trucks can be based on models or inputs that don't consider real world variables.

In a study on copper, researchers found that not accounting for blast movement can lead to up to a 20% misclassification of material (ResearchGate, 2018).

Why It Hurts Recovery

Once material has been misclassified and dumped on the wrong stockpile, the effects of that error can be seen all the way through the mill. Poor classification and stockpile variability can hurt recovery efficiency by up to 10% (AusIMM, 2021).

Having high grade material put into a marginal ore stockpile essentially removes that parcel of ore from being able to make it to the mill with the correct treatment. If a parcel has been overvalued, it has now been incorrectly used to optimize other parcels, without considering the true metallurgical characteristics. Not only does this introduce a degree of inaccuracy with your feed material, but it also adds unnecessary steps and energy to the re-handling process downstream.

An Example Scenario

Say that a truck has been classified as coming from Block 42, a 0.85% Cu parcel. However, due to blast misalignment, a 1.05% Cu portion of block 43 has been displaced and put into the truck. Due to the blast movement not being accounted for, and Block 43 being overgeneralized, the truck is routed to the marginal ore stockpile. After weeks of that stockpile being fed into the mill as part of a low-priority blend, the ore is processed at a lower energy with poor flotation recovery and overall decreased mill performance. Not only have you decreased your overall recovery, but you've skewed your reconciliation efforts from the incorrect grading of the misallocated parcel.

How To Stop Losing Value

To combat the loss of value, here are some steps we've seen work effectively in changing how a mine routes material and protects its high-grade parcels:

Modeling blast movement

Using vector offsets, or even AI, ensure that dig blocks account for blast misalignment.

Upgraded classification logic

Using sensor data or other inputs, ensure classification isn't relying on outdated drill logs.

Integration

Ensure that dispatch, ore control, and reconciliation all have access to updated grade information.

Feedback loops

Use mill performance as feedback to improve routing accuracy.

With these changes, we've seen improved recovery rates, stockpile blend consistency, and trust in the planning from technical teams at a number of different mines.

3 Strategic Takeaways

Ore routing is a value decision

Ensure its treated as such, and that the costs to other departments are considered when making those decisions.

Misallocation of compounds

One incorrect dump can skew multiple different variables. Ensure that your classification logic accounts for the variables that affect other departments.

Integration wins

You don't need to invest in new hardware, but ensuring your various systems are able to communicate can provide huge benefits.

Conclusion: You Can't Afford to Guess

Misallocation of ore is not a performance issue, but a failure of the system to protect the value of the material based on its characteristics. If your current stockpile routing practices are outdated, or rely on old data, it might be time to improve the communication and data flow between your geological, dispatching, and metallurgical departments. At NTWIST, we partner with mines to make sure that every truck is being utilized correctly, and that every piece of ore has a chance to meet its potential. After all, every tone counts when it comes to stockpile selection.

People Also Ask FAQs About ore misallocation

What is an ore misallocation?

Ore misallocation is when material is sent to the wrong stockpile or destination.

What causes ore misallocation?

Some of the most common causes of ore misallocation include blast movement, inaccurate classification, outdated models, and routing errors.

How does misrouted ore affect recovery?

Misrouted ore can negatively impact stockpile variability and affect blending, processing, and overall recovery efficiency.

How can mines prevent ore misrouting?

Mines can prevent ore misrouting by using updated models, ensuring accurate classification, and utilizing better data.

Can AI improve ore routing?

Yes, AI can be used to analyze geological, operational, and processing data to improve the accuracy of ore routing.

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