Supplying concrete to shore up mine tunnels several kilometres under ground isn’t a job for the faint-heated. It also needs a tough truck that has to carry a lot of safety gear.
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As General Manger of Assets for Barminco, Peter Campain is responsible for supply, maintenance and capital acquisitions for all of Barminco’s contract operations. With contracts right across the country producing copper, gold, lead, zinc and nickel, one of the site activities is supplying concrete to the shotcreting operations underground with a fleet of 21 Metro-Liners.
“Shotcreting involves spraying concrete on to the walls to support the tunnel,” says Peter, “and it’s a 24x7 operation, so these trucks are working pretty hard.”
In a typical site the Metro-Liners have to negotiate a seven-kilometre tunnel with a 1-in-7 grade.
“There’s only room for one truck at a time,” says Peter “so if they meet something coming the other way there’s a pecking order – the bigger vehicle or the one going down gets priority, the others have to pull off to give way.”
Peter’s Metro-Liners are a long way from the ones you see every day on the street.
”There’s a bit of resistance to road trucks being used underground because of the risk of brake failures on the constant grade, so we’ve got these ones fitted with a retarder and an emergency brake on the front rear axle.”
Other safety features include a roll over canopy and a fire system, and, as you’d expect, bolting on all this extra gear takes a bit of customising.
“We were doing all these modifications ourselves,” says Peter, “then the Mack engineers came and had a look at what we were doing and told us they could deliver them with a lot of it already done. They re-arrange the back of the truck for us in the factory now, and not having to relocate and remount parts of the truck every time probably saves us something like $20,000 per truck.”
Where most trucks have 8mm chassis rails, the Metro-Liners come with 11mm rails and a GVM upgrade so they can carry 6 cubic metres of concrete.
“A lot of work goes into these trucks,” says Peter, “we have to take them to three different workshops to get all the parts fitted, and our local Mack dealer does that for us with their trade plates, then take it back and get it registered if required.”
The water underground is intensely salty, ten times that of seawater, so the trucks are under constant assault, but salt is the least of their problems.
“In the base-metal mines, they’re extracting a sulphide ore that creates sulphuric acid when it gets wet,” says Peter, “so after a while the bodywork on these trucks doesn’t look too pretty, but we still get about five years out of them.”
Peter’s fleet is a perfect example of Mack providing the truck to suit the application, so it’s no surprise that he’s buying six more Metro-Liners this year.
“With us every truck is a factory order,” says Peter, “Mack have spent the time getting to know our business and they’ve stepped up to meet our requirements. Another brand tried to convince us to change last year, but they didn’t give us enough incentive. Ours is a specialised business, but Mack know what exactly we need and they deliver it.”