Boulder Detection Installation & Sensing Technology
Accurate oversized rock detection depends as much on where and how material is measured as on the detection algorithm itself. In bulk material handling systems, rock size is not static — it changes as material moves, spreads, and mixes. The choice of installation location and sensing technology determines whether the system produces a representative and reliable measurement.
This page explains the practical engineering behind the Boulder Detection System used for real-time primary crusher feed protection.
Why installation location matters
Oversized rocks rarely appear as isolated objects. They are mixed with fines, medium-size rock, and voids that change continuously as material moves.
If detection is performed at the wrong location, measurements become biased or incomplete.
The most representative measurement points are:
- Dump pockets and discharge points
- Transfer points and feeder inlets
- Conveyor belts
At these locations, material is:
- Spread out
- Moving in a controlled direction
- Not hidden inside a pile
This allows surface-based measurement systems to see and analyse individual rocks reliably before they reach the crusher.
Why surface-based measurement is used
Surface-based sensing is used for boulder detection because it is the most practical way to deploy reliable oversize monitoring in an operating plant.
Optical systems mounted above conveyors, feeders, or dump points are:
- Non-contact and non-destructive
- Simple to install without modifying equipment
- Cost-effective compared to full volumetric scanners
- Easier to maintain in harsh environments
Surface measurement does have a limitation: it only sees what is exposed. Rocks buried inside a pile or hidden beneath fines cannot be measured directly.
For this reason, surface-based boulder detection works best when installed at controlled flow points—such as conveyors, feeders, and discharge points—where material is spread out and individual rocks are visible. These locations provide the most representative and actionable view of what is actually about to enter the primary crusher.
2D and 3D sensing in boulder detection
Boulder detection systems use 2D cameras, 3D cameras, or both, depending on the application and where the measurement is taken.
For oversized rock detection, 2D surface-based measurement is usually enough. Large rocks are identified by how much surface area they occupy relative to the crusher opening. On conveyors, feeders, and discharge points, this gives a reliable picture of whether a rock can physically enter the crusher.
In practice, boulders are not always fully visible at the first measurement point. They can be partly covered by fines or other material and become exposed later as the material drops, spreads, or transfers. For this reason, installing cameras at more than one location increases the chance that an oversized rock will be detected before it reaches critical equipment.
3D sensing is used when height, volume, or load shape matters. This is typical on uneven truck loads, dump piles, or when volumetric information is required. In these cases, depth data adds useful information that a 2D image alone cannot provide.
In real plants, the choice of sensing technology is influenced not only by what needs to be measured but also by installation complexity, maintenance effort, and overall cost of ownership. How these factors affect downtime, maintenance, and return on investment is covered in Prevent Crusher Downtime.
Preferred installation points
Truck discharge and dump pockets
Detect oversized rocks as material leaves the truck, allowing problematic loads to be identified before they enter the plant.
Conveyors and transfer points
Provide stable, repeatable surfaces for measurement. As material spreads and moves, rocks that were partly hidden in the truck or dump pocket often become more visible here.
Feeder and crusher infeed
Acts as the final check before material enters critical equipment.
Using detection at more than one of these locations improves reliability. A boulder that is covered by fines or other material at one point may become exposed later as the material drops, spreads, or transfers.
Multi-camera system design
In plants with difficult or variable material flow, multiple cameras are installed at different locations and angles. This allows the same material stream to be observed as it changes shape and presentation, increasing the chance that oversized rocks are detected before they reach the crusher.
The number of cameras and their placement are chosen based on layout, dust conditions, and how consistently material is presented to the sensors.
FAQ — Installation & Sensing Technology
Where should a boulder detection system be installed?
The most effective locations are truck dump pockets, conveyor belts, transfer points, feeder inlets, and crusher infeed chutes. These are controlled flow points where individual rocks are visible and the measurement is representative of what is about to enter the crusher.
Is it better to detect boulders on trucks or on conveyors?
Both have value. Truck detection helps identify problematic loads early, while conveyor-based detection provides a stable, repeatable measurement just before material reaches the crusher. Many plants use both to improve detection reliability.
Why not measure boulders on stockpiles or static piles?
Stockpiles hide most of the material beneath the surface. Optical systems cannot see buried rocks, which makes measurements unreliable. Controlled flow points provide a far more representative view.
Is 2D camera detection accurate enough for oversize rocks?
Yes. For oversized rock detection, 2D surface-based measurement is often sufficient because large rocks can be identified by their projected size relative to the crusher opening. This is especially true on conveyors and feeders where material presentation is consistent.
When is 3D sensing needed?
3D sensing is used when height, volume, or load profiling is required, such as on uneven truck loads or dump piles where depth information adds value.
Why use multiple cameras instead of one 3D scanner?
Multiple cameras placed at different points or angles can detect oversized rocks that may be partly covered by fines at one location and exposed later as material drops, spreads, or transfers. This often improves detection reliability with lower cost and complexity than relying on a single 3D measurement.
Can detection be added later at more locations?
Yes. Additional cameras can be added at other dump points, conveyors, transfer points, or crusher infeed locations as operating needs change.