Oct 24, 2019

Top gun goes deep at Pajingo

Top gun goes deep at Pajingo Pit N Portal Australian operations manager Paul Twine.

There’s another top gun in the Queensland hardrock mining industry.

Pit N Portal is venturing into Queensland underground mining on the back of expansion investment at Minjar Gold’s Pajingo operation near Charters Towers.

The company has an existing relationship with Minjar Gold at its Marvel Loch operation in Western Australia. 

The foray into underground mining in Queensland is on the back of Pit N Portal’s Townsville-based equipment hire operations that has been in place since 2002.

They had broken new ground both literally at the decline and metaphorically, by using an excavator with a row header to build the decline, said Pit N Portal Australian operations manager Paul Twine. 

Industry-first approach

“That’s the first time it’s ever been done in the industry, sending an excavator with a row header underground in mining,” said Mr Twine. 

“It’s done in tunnels, but not in mining. This is the first time that it’s actually gone underground. 

“Usually you cut the first 5m, and then pull out and start blasting. But because of the ground, we wanted to push it as far as we could and we went in 18m, and then we started blasting from there.

“So (the ground) it’s very clayey. Which brings the same challenges, keeping a tight profile, as you see there, and being able to control, I suppose, the over-break (outside the design profile). 

“The whole job to the 30m mark has been two per cent over-break, which is excellent in clay. Okay, so that’s a big milestone in the mining industry.”

The excavator was 17m from the surface and the crew was reverting to conventional boring and firing methodology in line with the risk profile, Mr Twine said.

Pit N Portal have a 36-month contract in which time they aim to recover 63,000 oz/gold  over six levels using a modified Avoca, bottom-up mining technique.    

While labour shortage was an issue across the industry, Mr Twine said they have managed to secure most of the skilled staff for the eight-man crews from Charters Towers.

Meanwhile, the efforts of the Pit N Portal crews have been recognised by Minjar Gold.

They had done a fantastic job in a very short space of time to mobilize drillers and equipment and start getting their area set up, said project manager Rob Baker.

Project manager Rob Baker.

“They have done very well in a very short space of time that bodes to the future,” said Mr Baker. “They are competent, they have done this before. 

“What you saw today, just little things like the pipe work going down the side of the box cut into the portal, we said we wanted all the pipe work to be as straight and as clinical as possible because that sets the scene. 

“So whenever a new person comes to the mine and they go over the crest into the box cut, they see this and they think good standard has been set from the get-go and I want to maintain that standard.”