There are several opencast mines on the Copperbelt in Zambia using large haul trucks to transport ore from the pit for crushing and processing, and extending the life of tyres plays a significant role in cutting costs and improving production, says on-site nitrogen gas generator supplier NitraLife.
Ensuring that the tyres on haul trucks are kept at an optimum pressure and temperature, extends the tyre life, and is one of the benefits of using high-purity nitrogen to maintain correct inflation.
NitraLife sales director Tom Sowry explains that oxygen and water vapour tend to degrade, oxidise or perish rubber over time, whereas nitrogen does not, as it is inert and moisture-free. In addition, over time, carbon dust builds up inside tyres during their working lives.
“Should the tyre overheat, owing to a mechanical fault on the truck, this carbon dust mixed with air can combust or explode with potentially catastrophic consequences for property and personnel. Filling off-the-road (OTR) tyres with nitrogen eliminates this potential risk factor and results in major cost savings,” explains Sowry.
A large OTR tyre can cost anything up to R400 000, Sowry points out, highlighting that most haul trucks have six tyres.
“Therefore, the cost of a NitraLife nitrogen generator is negligible if the cost and safety benefits are taken into account.”
In addition, Sowry notes that large OTR tyres have a long replacement lead time and have to be imported. “Transporting these tyres to Zambia calls for the use of abnormal load low-bed trucks, which further increases the cost of already expensive OTR tyres,” Sowry notes.
From a safety perspective, he further explains that, on some mines, the use of nitrogen in tyres is also a precaution against OTR vehicles’ tyres exploding when struck by lightning.
“If a haul truck with air-filled tyres is struck by lightning, there is a possibility that its tyres could explode, causing damage to the vehicle.”
Lightning storms are a common concern at a number of mines on the Copperbelt, Sowry points out, noting that, before nitrogen was introduced to inflate tyres, haul trucks on some of the mining sites would be parked during lightning storms.
“Now, with nitrogen tyre inflation, this hugely expensive downtime is also eliminated,” he says.
He further explains that from a safety perspective, it is important to avoid the risk of injury to people and damage to equipment.
“Should there be a lightning strike and subsequent tyre explosion, repercussions – in the form of potential loss of life or injury to personnel and damage to vehicles and equipment, as well as the obvious financial implications – would be severe.”
In terms of damage to vehicles, Sowry notes that if a mine – for example – operates 20 haul trucks and one of these is put out of commission, owing to a tyre explosion, the mine loses 5% of its production capability and, possibly, a similar percentage of revenue in the weeks while the vehicle is being repaired or replaced.
When weighing up the potential associated costs, the price of a NitraLife generator is minimal, he adds.
“While there have been a few tyre explosions on Southern African mines over the past few years, none of these were on mines where the NitraLife tyre inflation systems were in use,” Sowry mentions, adding that NitraLife has, therefore, proven – in practical terms – that nitrogen inflation does its job effectively.
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Meanwhile, Sowry tells Mining Weekly that the laser-cutting and fabrication sectors have sourced nitrogen in cylinders in the past, which is a “potentially costly system with some inherent challenges”.
However, with the signing of an agreement earlier this year between laser-cutting and fabrication capital equipment distributor First Cut and NitraLife, Sowry aims to change this.
In terms of the agreement, First Cut has exclusive distribution rights to NitraLife’s NitraCut generators.
“When we first saw a NitraLife NitraCut generator connected directly to a fibre laser we had recently sold, we were excited by the potential of being able to supply an uninterrupted, affordable supply of nitrogen – on-site and on-demand – to all our Bystronic laser customers,” says First Cut MD Andrew Poole.
Although the agreement does not have direct bearing on mining in Zambia, Sowry notes that the agreement stems from NitraLife being able to supply NitraCut nitrogen generators specifically to the laser cutting and fabrication sectors.
From a laser-cutting perspective, however, the agreement between NitraLife and First Cut means FirstCut could potentially supply a laser-cutting machine, for example, to a Zambian company.
“The Zambian operation could make use of the NitraCut generator, which would free it from the challenge of having to source nitrogen in cylinders from a logistically inaccessible or distant supplier,” Sowry enthuses.
NitraLife already supplies several large mines on the Copperbelt, he adds, noting that the largest operation is mining company First Quantum Minerals’ Kansanshi copper mine, in the North-Western province of Zambia.
“The mines in the north of Zambia and in the southern part of the Democratic Republic of the Congo represent a great concentration of opencast operations, with a considerable scope for growth for NitraLife,” he states.
A further advantage in these remote areas, Sowry adds, is that the maintenance needed to keep the NitraLife generator operational is minimal.
Maintenance consists of a six-monthly prefilter change, which NitraLife technicians carry out at the mine site. However, this maintenance can also be done by the mine’s technicians after training.
Once a year, as part of its quality assurance protocol, NitraLife carries out a filter change and simultaneously checks on gas purity and flow rates, among other operational aspects.
“NitraLife takes pride in training its customers, particularly those in remote areas, in the correct operation and maintenance of its nitrogen generators. NitraLife has an informal slogan – ‘we only sell what we can support’,” Sowry notes.
He adds that this strategy is intended to protect NitraLife’s “excellent” reputation for high-quality products, which are well supported.
“Although it has been operational for less than a year, NitraLife’s new NitraCut division is working overtime to keep up with the orders for its nitrogen generators,” Sowry enthuses.
NitraLife’s offering reflects “true value” when one considers that the larger the tyre is, the larger the cost of the tyre will be. Therefore, Sowry says, a significant sum will be saved by using nitrogen to inflate haul truck tyres.
“It makes sense for any opencast miner to fill its OTR tyres with nitrogen,” he concludes.