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Sandvik enables efficient drilling

World Coal,

Conservation and productivity are issues everyone in the mining industry faces. How can we make operations safer and cleaner, while spending less time and money? These challenges are frequently seen as mutually exclusive. But a product has been developed to address both needs: reducing environmental impact and operating costs.

Sandvik’s compressor management system

The Sandvik compressor management system (CMS) tackles the two primary issues facing mines today: increasing productivity and reducing environmental impact. The CMS provides a solution to the inherent inefficiencies of rotary blasthole drills that have a direct connection between the engine and compressor. The system works by isolating the compressor and eliminating the need to maintain pressure when the machine is not drilling. This reduces the load on the engine, saving a significant amount of fuel and reducing wear and tear on the engine.

Sandvik initially tested the system at Drayton coal mine in the Hunter Valley in New South Wales, Australia. The CMS was retrofitted to a DR460 rotary drill and resulted in a fuel saving of 33%. The results were promising – but could they be replicated?

Case study: Cloud Peak Energy

Cloud Peak Energy Inc. is one of the largest coal producers in the US, supplying the country with about 4% of its electricity. The company operates three opencast coal mines in the Powder River Basin (PRB) in Montana and Wyoming and is the only company that mines exclusively in the PRB. Cloud Peak’s assets are comprised of properties acquired from several other companies and it specialises in the production of low sulfur, sub-bituminous coal.

“We consider ourselves leaders in our industry in conservation and environmental excellence,” said Mark Gilbertson, director of asset management for Cloud Peak. “There is a cost to that, but some of the resource conservation efforts wind up being positive financial decisions as well.”

Cloud Peak became Sandvik’s partner to prove its high pressure CMS in the US.

A one-time guarantee

Cloud Peak was interested in the proposed benefits but questioned if the system could really save 25 – 30% of fuel. Sandvik was confident the CMS would deliver, and so the company did something it never does: it offered Cloud Peak a one-time guarantee. If the system delivered 90% of projected savings, Cloud Peak would purchase the CMS at full price. If it underperformed, Sandvik would remove the system at no cost.

“That pretty much takes the risk away,” Gilbertson said. “We understood the science, so we believed the technology was going to work. We contacted our folks at the site, and they said: ‘If it really does what it is supposed to do, we want all of it’.”

Installation of the compressor management system

For the installation, Sandvik retrofitted the CMS onto a 14 year old D75KS rotary DTH drill. The companies chose this machine because it has been in full production for years, providing a solid reference point for the historic fuel consumption. And though the rig is approaching 60,000 hours, Cloud Peak expects to keep the machine in production for years to come, giving time to track the progress of the CMS.

Sandvik estimated that the CMS would save 23% of fuel. This was adjusted down from the original estimate due to the change in hole size from 10.63 in. (26.99 cm) to 11.25 in. (28.58 cm). The larger hole size increases the amount of air flow and thus fuel consumption while drilling.

Once the system was installed and calibrated, Sandvik technicians used the Engine Control Module (ECM) data as a reference point. After about 30 days they checked the drill’s performance.

Exceeding Cloud Peak’s expectations

Before the installation, the ECM showed that the D75KS used 22.9 gallon/hour of fuel. After running the Sandvik CMS for five weeks, the rig was only using 16.9 gallon/hour – a reduction of 26.2%. That translates to saving about 24,000 gallons of fuel, US$ 108,000 and more than 300 t of carbon emissions saved every year, based on 4500 hours of operation and US$ 4/gallon. Additional savings are expected from increasing the engine life. “If it had worked half that well, we still probably would have gone with it,” Gilbertson said.

Kelly Rice, the Cloud Peak drill mechanic operating the D75KS, offered his perspective: “Changing out steels is when it really makes a big difference,” Rice said. “And the tram times, it saves a lot of fuel. It also helps you start in cold weather. It makes a big difference. It takes a load off the engine. Once it fires, it is a lot easier to run.”

Gilbertson backed that up: “Kelly’s pretty excited thinking about not changing starters and batteries in the middle of the winter. “

A clear choice

According to Gilbertson, the choice to purchase the Sandvik CMS was clear: “The CMS saved about 500,000 gallons of fuel between overhauls,” Gilbertson said. “As part of our environmental stewardship programme, we work to reduce fuel use and emissions. The Sandvik CMS will help us do both.”

Cloud Peak purchased two new Sandvik rigs for 2013 with Sandvik CMS installed.

Ken Stapylton is the vice president of rotary drilling at Sandvik Mining. This article originally featured in the March 2013 issue of World Coal.

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