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Mining crew turns to combo screens in bid to strike pay dirt

 

Through a decade of a popular mining reality TV program, originally a team of amateur miners entertained audiences around the world with their feats in the US and abroad. Once they were back on home soil, they turned to a range of combined incline/horizontal screens to exploit their local knowledge.

From the wilds of Alaska, to the remote corners of the Canadian Klondike, to the jungles of Guyana, Dave Turin and Todd Hoffman have spent the best part of a decade travelling the globe in search of gold as part of the Discovery Channel’s TV show Gold Rush. But their toughest challenge was in none other than their home state of Oregon.

The pair were mining a parcel of dry desert ground in northeastern Oregon. Over seven seasons (December 2010 to early March 2017), longtime fans of the show witnessed a massive evolution of the crew that were once just a rag-tag group of inexperienced miners. Today, they are seasoned professionals capable of pulling in more than 3000 ounces (or 85kg) of gold worth more than $3.3 million in a single season.

After a record-breaking haul in season six and anxious to tackle a new mining challenge in season seven, Hoffman and Turin set up camp in Oregon, a location much closer to their families and a historically gold-rich area. They entered their new mining claim armed with a highly productive wet wash feed system, along with a combo screen from Johnson Crushers International (JCI) that Turin estimated could increase their operational efficiency by 20 per cent.

However, the 14-person crew faced enormous unseen challenges in season seven. Once they began excavating, their struggle to find the pockets of rich gold left behind by the previous dredge became so difficult that it only allowed them to sluice less than 6000m2 over the course of the season. That’s less than two per cent of the material they sluiced in season six.

Turin said, though, that is the risk of any new mining endeavour. “Each year, the biggest challenge for us has been trying to figure out how to mine the resource,” Turin said. “You can build the right plant and have the right tools that allow you to clean and sort and size your rock, but at the end of the day, it always comes back to the source. Here, we underestimated how successful the original dredge was at capturing the gold in the area, and that’s the reason we have such a small pay zone. But you never really know until you get right down in there and start digging.”

SETTING HIGH EXPECTATIONS

The Oregon claim they mined was a renowned placer deposit that was once a river channel that meandered through the valley. The secret to mining an area like that is finding the deepest channels in the mature river plaster ground, because that is where the deepest gold lies, Turin said. Finding those deep channels was key if the crew wanted to meet Hoffman’s ambitious season goal of 5000oz (or 142kg) – worth upwards of $USD5 million ($AUD7.6 million).

The bottom of the claim’s gold deposit consisted of one-metre boulders encased in mud, which could have had gold settled within the mud. That would make processing the rocks more challenging because the larger stones would have to be scrubbed clean to remove the gold.

The process started with a wet wash grizzly feeder, which shook the rocks down and began cleaning the bigger boulders. The larger rocks bounced across the top of the feeder, and the smaller rocks, dirt and gold that were washed off the boulders were transferred to a blademill. The blademill scrubbed the rock with spiral flights and broke the clay off with paddles.

Material was then fed to the combo screen, which separates based on size. Any material smaller than the minus 12.7-micron went into the sluice box, where the gold was trapped in the riffles and carpet. At the end of the day, the crew cleaned the sluice box and recovered the fine gold material.

It didn’t take long, however, before Hoffman and Turin realised that they were not hitting the pockets of rich gold they were hoping for.

“The challenge with this site is that the dredge went up the middle of this valley,” Turin said. “So we wanted to do two things: get underneath where the dredge went, and get the side pay that it left.

“What we found was that the dredge did a great job. We were chasing a pay zone where we thought we would be able to run about 12 hours a day. In the end, we didn’t find the pockets of rich gold that exist in the claim.”

The Gold Rush crew was initially optimistic that upon set-up on the mining claim, the combo screen could increase operational efficiency by 20 per cent.

SMOOTH SCREENING

Although Turin had plenty of experience with a variety of screens in his mining career, he rated the combo screen as one of the best screening tools he’d ever used.

“I love the combo screen,” he said. “I was a bit apprehensive initially with the added size and height and the fact that it looked to me like it was going to be out of balance, but once we fired it up, it ran so smoothly.”

“Since we turned it on, it’s the smoothest running screen we’ve ever used,” Hoffman said.

The combo screen from Johnson Crushers International (JCI), part of the Astec Industries group, combines the characteristics of both incline and horizontal screens, and delivers productivity, efficiency and flexibility in wet and dry applications. The combo screen also offers a sloped feed zone for quicker fines separation, and is the only sloped screen that provides the benefits of a triple-shaft vibrating mechanism. These advantages include anti-plugging/blinding, extended bearing life, application flexibility and stroke amplitude adjustment, according to Nick Hahn, JCI’s product development manager.

“The combo screen allows you to quickly get your oversized material out first, and then at the bottom you’re getting perfect fine screening,” Turin said. “At the beginning the material’s not just moving with the vibration, it’s rolling over itself, which then allows it to get into the opening.”

Turin was no stranger to JCI equipment. Long before joining Gold Rush, he earned his degree as a civil engineer and served as the vice president and quarry manager of his family’s aggregate business, Mt Hood Rock, just a couple of hours away from the Eugene, Oregon-based manufacturing facility.

“We’ve used JCI products for years,” Turin said. “Their equipment has always held up for us, and it’s always competitively priced. In my family business, we’ve always looked at long-term goals. We don’t do things on a short-term basis – we want to know how long something is going to last. We’re not interested in buying something and using it for a year. We’re interested in buying something and having it last 15 to 20 years.”

“The thing I especially like about JCI is that they’re not just sitting there making exactly the same product every single year,” he continued. “I like the fact that they’re trying new things, like this combo screen. They’re willing to take a chance, take a risk. That’s how you improve.”

As the 316 Mining crew raced against the clock to capture as much gold as they could before the season’s conclusion, there was no time to waste waiting for parts – which was a big reason why Turin appreciated being back in Oregon.

“When we were in the jungle, it would be weeks before getting parts,” he said. “When we were in the Yukon, it was literally five, six days before you could get a bearing. So being in Oregon is nice. JCI has all of their parts ready to go, you can just make one phone call and I’ve got a part by the next day.

“But I know that next year, wherever we may be, we’re still going to be taken care of when it comes to parts and service,” Turin continued. “All of the easy gold is gone, so now we have to go to the remotest parts of the planet to find gold. I’ve had to learn how to adapt and find people that can get me parts immediately, and JCI can do that. I don’t know where we’ll be next season, but I do know that I want to take that plant with me. As far as I’m concerned, that will go with us.”

Material is fed to the combo screen, which separates based on size.

FOCUSING ON THE FUTURE

While Hoffman and Turin did not find the golden payday they hoped for in Oregon, they were already thinking ahead to subsequent seasons. Though he never imagined himself a reality TV star, putting mining in the spotlight internationally is an important responsibility, Turin said.

“Worldwide, there are millions and millions of guys who mine for a living, and that’s how they pay the bills. And in a certain respect, I represent those guys that are sitting at home watching the show. And honestly, I want them to be happy with me. I want them to say, ‘Hey, that’s one of us!’ I want them to embrace what I’m doing and I want to show the positive aspects of mining.

“And for the most part I’m proud of what they show on TV,” he said. “We get to show how hard the work is, but then we also show how gratifying it is. There aren’t many jobs where you get the instant satisfaction after busting your butt and getting your hands dirty, but we get to walk up to the sluice box at the end of the day and see gold in it. In the past, I would crush for weeks and weeks and we would have a great big pile of rock and you’d think, ‘Wow, that’s a great pile of rock.’ But here, you can walk up to the sluice box and immediately see all that gold in the box. There’s no better feeling than that. That’s why we mine.”

The JCI combo screen is available through Astec Australia. 

Source: Astec Industries

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