Optimizing Mining Operations - Oversize Detection and Management

In mining operations, oversized rocks (sometimes called boulders) can significantly impact productivity. They cause crusher blockages, leading to downtime and reduced efficiency. This article explores practical solutions for detecting and managing oversized material to boost operational performance and how to plan for integrating these solutions into operations.

The Oversize Challenge

Oversized rocks are a common cause of production bottlenecks in hard rock mining operations. They typically result from:

1. Edges of blast patterns
2. Local hard pockets not individually targeted for increased blasting
3. Restrictions in drill-and-blast practices
4. Ore bodies having lower and more varied grades ?

The impact of this issue is substantial. Some sites report more than 25 hours of crusher downtime per month due to oversized rock blockages. This doesn't account for the additional wear and downtime associated with rock breakers used to manage oversized material or the additional wear oversized material causes on the crushers.

Traditional methods like grizzly screens help prevent oversized rocks from entering crushers, but they don't eliminate the problem. When blockages occur, manually operated rock breakers are often used to clear them, halting all throughput and contributing to significant crusher downtime. In the worst cases, crusher operations can be stopped for many hours due to a single event, with cranes and multi-person crews working inside the crusher, increasing the risk of harm required to clear the blockage.

You can find more information of the causes and impacts of oversized rocks in this post .

Oversize Detection Technologies

Visual detection methods range from low-tech to high-tech solutions:

1. Manual Spotting: Excavator operators identify oversized rocks during loading. While cost-effective, this method is prone to human error due to the demanding nature of the operator's role.
2. Camera-Based Systems: These technologies use machine vision and image processing to detect oversized rocks. Cameras can be mounted on gantry structures on haul roads to scan truck loads, or excavators to check every bucket movement.

Camera-Based Detection

Camera systems offer intuitive detection and can provide secondary benefits like truck tray and excavator bucket condition monitoring. However, their effectiveness is limited in low visibility conditions common in dusty mine environments.

Vibration-Based Detection

Vibration-based solutions offer an alternative approach that's less affected by environmental conditions:

• Smart sensors installed on haul truck trays use accelerometers and gyroscopes to capture truck movements during loading.
• These vibrations are analyzed to determine rock sizes within the load.

Advantages of this method include:

• Reliable operation in dusty conditions
• Ability to detect large rocks throughout the load, not just at the surface
• Protected sensor placement under the tray

Vibration-based systems require an initial tuning and calibration phase and are deployed on each individual truck. They can be complementary to existing visual detection methods, as their benefits counteract the disadvantages of visual methods.

See our previous post for a more detailed comparison of oversize detection solutions.

Effective Integration Strategies

As with most technology solutions, a well-planned integration strategy is vital to realising the value of oversize detection solutions. Implementing these technologies effectively requires careful consideration of several factors:

Stakeholder Alignment

The problem of crusher blockages due to oversized rocks sits at the intersection of two different domains of a site – mining operations and fixed plant. Effective implementation of an oversize detection solution requires alignment between these two groups of stakeholders in order to implement an effective truck re-routing or early warning strategy.

Reliable Decision Support

The system should allow operators to dynamically adjust sensitivity and specificity to match optimal detection action to observed operating conditions. For example, when truck queuing is high, it may be preferable to divert more trucks (higher sensitivity) even if it means accepting more false positives (lower specificity). The converse holds when there is less queuing at the crusher. For more details on the issue of sensitivity and specificity, see this post .

Timely Notifications

Early notifications are crucial for thorough decision-making and prompt action. If using gantry-mounted, camera-based methods, these must be positioned on haul roads to provide sufficient time for operators to react to alerts.

Network Management

Solutions must balance data transmission with network capacity. Edge processing capabilities are advantageous, reducing the strain on network bandwidth and ensuring critical systems (e.g. autonomous haulage) maintain priority.

Flexible Integration

Technologies should integrate with dispatch systems and fleet management systems as necessary. API-based access to the data from an oversize detection system can be critical to support integration with the mine’s existing data management and dispatch systems. This integration is particularly important for compatibility with auto-haul operations, and for minimizing the cognitive load on operators who are often already managing multiple screens and systems.

Conclusion

As the mining industry continues to face pressure to increase production efficiency, use decreasing ore grades, reduce costs, and minimize risks, addressing the challenge of oversized rocks becomes increasingly important. By implementing and properly integrating advanced detection technologies, mining operations can significantly reduce crusher downtime, improve overall productivity, and ultimately enhance their bottom line.

When deploying oversize detection solutions, mining operations should:

• Ensure buy-in from both mining and fixed plant
• Balance detection accuracy with operational efficiency
• Minimize additional cognitive load on operators
• Ensure the solution is adaptable to changing site conditions

?To learn more about a field-proven vibration-based oversize detection technology, check out the LoadWise website .

Beyond Oversize Detection

Furthermore, mine sites adopting the?LoadWise?system can benefit from more than oversize detection. A new aspect severely affecting mining is that the best ore grades have now been depleted, and lower grades are mined and concentrated.?The lower grades contain seams of softer soils like clay, increasing the incidence of chute and transfer blockages. The?LoadWise sensors can also be tuned to detect softer materials, a blockage precursor. In addition, AMOG's SensaWise sensors, added to the transfer points, detect natural frequency response change, which is a precursor for a blockage. This is but one example of many possible applications of edge sensor use for early detection that enables mine sites to manage ore processing to promote maximum production.?Follow us for more on this in the future.