OceanaGold has retired one of its massive Hitachi EX3600-5 excavators from its Macraes Gold Mine in Central Otago, but its lifetime of delivering exceptional reliability and productivity is not over yet.
The big orange machine was OceanaGold’s first foray into Hitachi excavators and was the number one production machine on the mine site until a second EX3600 was purchased by OceanaGold in 2010.
“From 2006 to 2010 it moved just over 20 million tonnes per year, which is a very high amount for a machine of that class,” says Pieter Doelman, the miner’s Technical Services and Projects manager.
“The EX3600-5 has been an integral part of the ongoing success at Macraes, and has been popular with our operators, who set several production records on it over its life. The machine was well matched with our truck fleet, which resulted in a low lifetime loading unit cost per tonne.”
The machine was deconstructed over a couple of weeks in the spring and then transported to Port Chalmers where it will be shipped to Hong Kong for use in barge operations.
During its lifetime, the excavator mined 214 million tonnes and clocked up around 74,000 hours at the mine. Five operators shifted more than nine million tonnes each on the machine, with Paul Barringer setting the record of 20.8 million tonnes overall.
Paul says it was an “honour and privilege” to drive such a massive machine. “I have a real passion for Hitachi diggers, and that machine was like my baby.”
As well as achieving the highest overall production on the EX3600-5, Paul regularly moved over 50,000 tonnes in a shift, and remembers hitting that milestone three nights in a row, which was “special” he says.
Although Paul is now retired (like the machine) he looks back fondly on the four years he spent with OceanaGold.
“It was more than a job to me. I’m so passionate about big gear and it was amazing to have the opportunity to drive the EX3600. I also loved the challenge of beating the younger fellas when it came to production, even though I was twice the age of quite a few of them.”
Another record breaking operator was Chris Cousins, who still holds the record for a 12 hour shift on the EX3600, moving 54,248 tonnes.
“I don’t remember too much about setting the record, but it was certainly a privilege to drive one of the biggest excavators in New Zealand on and off for eight years.
“I loved the comfort, power, and the view out of it was outstanding. This machine is a piece of history. I’m sad its days at OceanaGold have come to an end.”
Four other operators at OceanaGold moved more than 50,000 tonnes in one shift on the machine.
Mike ‘Moses’ Scurr, now the Mobile Fleet Maintenance foreman at OceanaGold, and Quentin ‘Soddy’ MacLeod (senior mechanic) have been part of the maintenance team since the EX3600-5 was delivered in 2005 (including a two-year stint as CablePrice employees working at the mine site).
They have both spent “a lot of hours” working on the excavator, says Mike.
“It has been an absolute workhorse, and a really good digger as far as reliability and productivity goes. It required a bit more maintenance to its structure as it got older but otherwise it’s been a great all-round machine.
“I’d much rather work on one of these diggers than a car, as you can walk around them, underneath them and beside the engine.”
He says the maintenance team was well supported by CablePrice during the machine’s lifetime, particularly when it came to big maintenance shutdowns.
“We’ve had CablePrice employees from Invercargill, Christchurch, and even Rotorua come to help us during the big shutdowns. We’d plan them carefully to try to get as much maintenance as we could done in a two-week period.”
Quentin ‘Soddy’ MacLeod remembers a few long nights working on the EX3600-5 to ensure it was ready to go for the operators.
“We had a few fun and interesting times, but overall it was a really reliable digger when you think about what we did with it at the mine.
“Moses and I did a lot of smart planning when it came to the maintenance, getting services done during wet periods, even if they were a bit ahead of schedule, so the digger could move dirt again as soon as the weather came fine.
“Tom Muirhead, who was our parts man used to shake his head and say we were experts at crisis management. We used to put the pressure on him to make things happen so we could keep the digger performing at a high level for the production team at OGL.”
Since the acquisition of the EX3600-5 in 2005, OceanaGold has exclusively purchased Hitachi when it comes to primary loading machines and the retired machine has been replaced by a new EX3600 that was built in February 2020, and is currently removing overburden almost 24/7 between four crews.
It has massive production, power, and toughness, with its Cummins engine producing a maximum 1944 gross horsepower and its fuel tank holding 7450 litres of diesel.
The machine can load a 181-tonne payload truck with ease, with five passes in just 2.5 minutes, says Pieter.
“Production is averaging about 2600 tonnes per hour, which is in line with our expectations. Like its predecessors, the new EX3600 is going really well so far.”