PROK’s HDPE rollers have provided the Australian mining industry with a lighter-weight alternative to steel. ABHR learns more about how the rollers are designed for long-lasting use in intense conditions.
Most mining conveyors are high-capacity and high-tonnage systems that put considerable load onto rollers.
In the iron ore sector, especially, rollers are often made from steel to ensure they are strong enough to handle the load.
However, the fact steel is a heavy material adds considerable strain to the manual handling process. The heavier a roller, the harder it is to manipulate by hand.
Ray Anderson, engineering manager at PROK, told ABHR that this can lead to increased chance of injuries on-site.
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“Changing a roller means someone needs to physically lift it into and out of position. The heavier it is, the harder it is,” he said.
“It can cause lower-back injuries associated with movement and rotation, as often the person will need to lean with the roller to get it into place.
“If the roller gets dropped, it can cause serious damage to anyone in its way, especially if it’s someone’s hand in a pinch point.”
PROK began working on a lighter roller that would still be strong enough to handle the intensive environment. The company undertook an extensive process, working with research institutions and the mining industry to find the right material and design that would work.
After years of development, PROK had developed a specially designed line of high-density polyethylene (HDPE) rollers that could support the changing mining industry.
Anderson said the plastic had proven itself in the market after having been in used for mining applications for years.
“HDPE can be UV-stabilised and can contain different additives to change its structural or mechanical properties,” he said.
“It’s stable, rigid and strong, a perfect mix for the mining industry.”
The rollers were released to the market around 2020, and have been installed all over Australia, particularly in the WA iron ore industry.
On average, the PROK HDPE rollers are around 40 per cent lighter than steel alternatives, allowing maintenance personnel to quickly and safely perform roller changeouts. The non-metallic tube also significantly reduces the likelihood of damage occurring to the belt in the event of a failure.
The rollers have now been operating in mines for two years, with miners praising the longevity of the rollers. One leading iron ore miner recently sought out PROK to help solve reliability issues with its existing composite rollers.
PROK replaced the rollers with its HDPE rollers, and after 12 months of continuous operation in a highly loaded conveyor, PROK HDPE has experienced zero failures.
Anderson said the rollers’ longevity was partially due to their high-quality sealing system.
“Roller failure often occurs when there is a failure due to contamination in the bearing housing,” he said.
“Once solid contaminants such dust enters the bearing, they can get caught between the raceway and the balls, creating micro indentations and small fragments. Over time, this promotes spalling and causes a chain event that cannot be reversed.
“Fluids entering the bearing will not only dilute the grease (reducing the effectiveness of the grease) but promote corrosion, again a chain event that cannot be reversed. Both solid and liquid forms of contaminant will result in a seized bearing days-months after entering.”
The bearing will become noisy, have increased vibration eventually seize and stop rotating, where it will either flog-out the bearing housing (ie the housing spins without the bearing rotating) or the shell will become fixed. These issues can cause unscheduled shutdowns to protect the belt from damage.
PROK’s HDPE rollers use a non-metallic housing and three-tiered sealing system with multi labyrinth and contact seals to protect the bearings from contaminants.
It also makes use of an internal seal moulded with a low-friction stainless steel running face that is positioned against a contact seal. This prevents the ingress of dirt into the bearing and optimises seal efficiency, resulting in a longer service life.
The rollers also include a unique method of monitoring wear.
“Mining companies can change out dozens of rollers on any given day, and sometimes this is done without knowing whether the roller has reached the point of potential failure,” Anderson said.
“Traditionally, it is hard to know how much and the type of wear a roller has experienced, especially when it comes to return rollers that are exposed to high levels of carry-back.
“That’s why PROK’s rollers include visual wear indicator technology to help mining companies plan their maintenance.”
A green inner layer is incorporated into the yellow rollers to act as a visual indicator for maintenance teams. This helps mining companies identify which idlers need to be replaced and can assist with implementing maintenance scheduling strategies or highlighting problematic areas.
Australian made
PROK is a proud Australian manufacturer, seeing it as a distinct advantage that complements its brand. The company manufactures its rollers at facilities around the country for use in local mines.
Wade Guelfi, the company’s general manager for WA and Southeast Asia, said PROK being on the doorstep of its major customer base creates greater opportunities for flexibility.
“Our local engineering and production capabilities are readily accessible to our customers,” he said.
“With new products coming online and continual changes in developing products, PROK’s excited to further invest in automated roller manufacturing to really complement the long-term contracts that our major mining companies have entrusted to our business.
“We’ve always been focused on Australian manufacturing because we believe it provides us with a distinct advantage. Having flexibility and local knowhow is a massive advantage.”