With a smart conveyor redesign, the team at one of BHP’s iron ore mines increased their material-handling capacity by 11% without altering operating conditions. Since reducing the total weight of their boom conveyor system by over 5 tons, the mine now has capacity to move an extra 1,800 tons per hour.
Finding a production bottleneck
The Projects team at this Western Australian iron ore operation identified a production bottleneck around their bucket wheel stacker-reclaimer. They realized their heavy-duty boom conveyor had reached its weight capacity, effectively capping production output and preventing upgrades to a more energy-efficient belt.
They wanted to use a low rolling resistance belt to improve energy efficiency but couldn’t without solving the weight limitations.
It was a typical conveyor system setup with standard steel rollers and steel frames: a default design found at most iron ore operations.
“Every mine site has at least five to ten conveyors and nearly 100% of them have this old-style design. It’s just the standard default design for all greenfields projects,” says Brayden Kubala, Principal Engineer – Idlers at PROK.
While these work fine in standard conditions, they are difficult to upgrade once they reach their capacity. Our technical specialists were invited to site to see if we could recommend any viable upgrade paths.
Our technical analysis
The boom conveyor on the site stretches approximately 165 yards (150 meters) as part of a stacker-reclaimer system. Reclaimers are weight sensitive so there are limits on how much weight they can hold and this ultimately impacts throughput.
We identified two key areas where they could significantly reduce weight with no compromise to structural integrity or performance:
- Oversized traditional frames
Their standard iron ore frame design, while robust, carried unnecessary weight. Each frame weighed 282 lb (128 kg), making the entire system extremely heavy.
- Heavy steel rollers
Conventional steel rollers, though durable, also added a lot of weight. With their specific load profile, we knew that lighter roller alternatives would perform the same while massively reducing overall weight.
Our engineers realized that addressing these two components would reduce the static weight of the conveyor structure, and free up capacity to transport more materials.
Our recommendations
We proposed two simple design improvements to reduce the static structural weight:
- Lightweight Carry Frame redesign
Re-engineering the carry frames with a custom lightweight design would cut the weight in half, from 282 lb (128 kg) down to 132 lb (60 kg) per frame. Modelled in Finite Element Method (FEM), we showed them how the new structures would respond to different loading conditions for the mine’s CV111 Boom Conveyor. At flooded condition, the frame satisfied the 1:350 deflection ratio; averaging 3.0 mm (of an allowable 6.1 mm).
The proposed new design used a ‘bent pipe structure’ rather than the traditional flat base member design.
“The design leverages a bent CHS profile with an increased second moment of inertia to increase resistance to bending. This allows us to satisfy the same design criteria for significantly less weight,” explains Brayden, who worked on the engineering re-design. This new design maintained the structure’s strength while significantly decreasing the static weight.
- HDPE roller replacement for load distribution
We recommended they replace standard steel rollers with HDPE rollers to reduce the carry roller set weight by 43%. “By adjusting the rollers from steel to HDPE, you can reduce some weight and then further reduce the weight by changing the frames from the old style to the newer style,” notes Kubala.
We also included hollow-shaft rollers — using two stubs and a tube — to further reduce weight while maintaining performance standards.
The overall weight reductions from the carry roller sets, carry frames, and return rollers – based on the respective quantities – are shown in the table below.
Smooth & fast installation
The mine’s asset maintenance and reliability teams agreed with our recommendations and developed a phased implementation plan to minimize operational disruption.
They began the project in April 2023, and completed installation within three months. PROK’s manufacturing team built the frames to exact specifications and installed them during scheduled maintenance windows. Our lightweight PROK HDPE rollers were installed into the conveyor system, with careful attention to load distribution requirements.
This approach provided a huge weight reduction with no major structural modifications to the boom conveyor itself.
Measurable results for BHP’s iron ore mine
Two years later, the reclaimer has seen significant operational improvements:
Huge weight reduction
A total weight reduction of 5.18 tons (4,700 kg) across the boom conveyor system, without major structural modifications. This allowed the team to upgrade the conveyor to a new low rolling resistance belt to improve energy efficiency.
Opportunity to increase tonnage
The new energy efficient belt led to an 11% increase in material-handling capacity without altering operating conditions, giving the team more production flexibility.
Improved safety and efficiency
The lightweight conveyor components reduced manual handling risks from installation through maintenance. As Brayden notes: “In the past 5-6 years, there’s been a major push to reduce manual-handling-related injuries. And that’s essentially what’s driven the HDPE roller to be so popular.”
The reduced component weight makes it easier for workers to safely handle parts during removal, transport and install. “Because of the lightweight benefits, everything from removing it from the crate to installing it makes it easier for a more diverse workforce to do the job and this is hugely important to companies like BHP,” explains Brayden.
Better energy efficiency
The weight reduction enabled the mine to install their planned low-rolling resistance belt, reducing energy consumption.
Brayden added “boom conveyors are often limited by weight and you always want to reduce that weight. There’s a number of benefits to doing it, but there’s not many negatives.”
“Extremely happy,” is how Brayden describes the client’s reaction two years on. “We’ve had a lot of interest from other iron ore sites as well and we’re delivering those projects now.”
This redesign shows that lightening your conveyor components lets you boost production capacity without major structural changes, while also making maintenance work safer.