By Lee Buchsbaum
Located in southeastern Montana just over the Wyoming border near the town of Decker, Cloud Peak Energy’s Spring Creek mine produced and shipped approximately 17.7 million tons coal in 2009, making it the largest coal producing mine in Montana. The calorific value for Spring Creek’s 80-ft thick contiguous non-parting coal seam averages 9,350 Btu/lb. That is slightly higher than the southern Powder River Basin (PRB) average of 8,400 to 8,800 Btu/lb and demand for it is greater. As a result, the mine’s customers have grown to include electric utilities, industrial customers and power plants throughout the U.S. and, increasingly, in Asia.
Conveniently located along BNSF’s transcontinental northern corridor, Spring Creek’s coal enjoys global reach. “We really are the most strategically placed mine in the PRB to breach Asian markets and, to date, the only one to really exploit any export potential. We ship significant export quantities to Westshore Terminals in Vancouver, B.C.,” said Bruce Jones, general manager, Spring Creek.
Even though it has been in operation for decades, Spring Creek has virtually re-invented itself since 2000. A progressive expansion project undertaken over the last few years has increased the mine’s production from 8.9 million tons in 2003 to 14.7 million tons in 2006. That year the expansion program entered another phase. Subsequently, production increased to almost 17.95 million tons in its highest level of production ever. In 2009, Spring Creek produced 17.6 million tons.” In 2008, when we mined just under 18 million tons, we were mining at a 19-million-ton per year clip until October when the bottom fell out of the worldwide economy. But, we recovered our pace by mid-March of 2009,” said Jones. With 238 employees, today the mine is producing at an annualized rate of 18 million tons.
Record Production & Growth
The end of 2009 marked the end phase of the mine’s aggressive three year expansion project including major changes to its haulage and loading programs. Today the mine can handle more trains and load them much more quickly. During those three years, the mine constructed a new state-of-the-art 8,000-tph load-out, expanded the rail loop, replaced its secondary coal crushers, doubled the capacity of its conveyor to the new load-out, constructed a new satellite near-pit coal dump facility, and upgraded the shop and added wash bay facilities.
To begin the changes, the mine built a new overland conveyor in July 2007. The new overland conveyor is just under a mile long. The first step of many major enhancements on throughput capacity was the doubling of the belt speed feeding the load-out.
The new load-out and the expanded loop track capacity allows the mine to host 150-car trains, though the maximum capacity has yet to be reached. “We’re only receiving 125-car trains, but we’re suited for longer. A few years ago the standard was 113 cars and it’s been creeping up since. We have three holding tracks or landing spots and can hold four trains up here at any one time,” said Jones.
After loading off conveyor scales for years, the mine started batch loading in 2007. Through controlled flood loading, the new batch load-out can fill a 115-car train in one hour and 40 minutes. The scales are so accurate they can load within 50 lb of the target weight. The old load-out had a maximum run rate of 5,200 tph. With the new load-out running at 8,000 tph “it’s a heck of a step change,” said Mike Mindham, plant manager, Spring Creek.
The mine also increased its direct run rate out of the pit, doubled the capacity of its Gundlach twin-roll secondary crushers. “We can rock and roll if we want to,” said Mindham.
The mine’s original near-pit truck dump features two 500-ton hoppers. There’s a feeder and single-roll crusher below each hopper and secondary crushers farther down the conveyor to reduce the coal to its final size. It is about one mile from the main pit to the main dump and crusher. Most of that trip is up-ramp though once rested, its only 1/2 a mile to the main crusher. It is a slightly shorter traverse for trips out of Pit 4 to the near-pit crusher which uses a Stamler feeder breaker to size coal. “The new near pit crusher also provides some redundancy for us. If there’s a repair required on one of the dumps, you can haul to the other crusher. You might be producing at a reduced rate, but your operations can continue either way while one system or the other is down,” said Keith Walters, manager of technical services, Spring Creek.
As Spring Creek prepared its pits, engineers matched the mine’s topographical and geo-technical requirements with the dragline parameters and production targets. This combination of factors required overburden pre-stripping down to a dragline mining height between 160- to 180-ft. Deeper areas are pre-stripped with a hydraulic rope shovel. “Though there’s probably less than 20% overburden that’s mined by truck and shovel,” said Gary Rivenes, executive vice president and COO, Cloud Peak Energy.
Acquiring New Mobile Equipment: Draglines and Haul Trucks
Key to Spring Creek’s success are its two draglines, a Bucyrus-Erie 1570 and a Page 757. The BE 1570 has a 78-cubic-yard (cu yd) bucket, the Page has a 54-cu-yd bucket. The BE 1570 was purchased from the nearby Decker mine several years ago and walked over. “The BE 1570 is a bigger machine and so it’s one that is prioritized. We push the dragline performance pretty far here,” said Rivenes.
Almost all of the low sodium production is stripped by the Page 757 in Pit 4, but not all of the coal it uncovers is necessarily lower in sodium. Overall, the BE 1570 exposes about 14 million tons and the Page uncovers about 4 million. As a smaller machine with its full capacity not required at current sales volumes, it is only scheduled to run 50% of the time, whereas the BE 1570 is scheduled to operate 24/7.
For haulage, Spring Creek has a virtually new fleet of eight 240-ton Komatsu 830E AC drive trucks. Delivered from November 2007 through January 2008, “it’s a relatively new fleet, they probably have 10,000 average hours. Over the years, our preference has shifted to Komatsu. We’ve developed good maintenance practices on them over time, and they’re reliable. And the costs are pretty good,” said Rivenes. The Komatsu trucks are fitted with combo bodies and all of them are used to haul either dirt or coal depending on what’s needed and scheduled.
Spring Creek is very proud of its tire maintenance program. Spring Creek’s program rewards its employees for extending tire life. It has enabled the mine to extend the hours of these very valuable components and the company rewards employees for tire performance.
“You want to make sure operators do not run over rocks, so we have an emphasis on good road maintenance practices,” Rivenes said. “You also want to make sure they check the tire pressure before the start of each shift.
“Each truck also needs to have a good rotation management practice. The front tires wear quicker than the rear, so this is vital for them to wear evenly. Once you have good maintenance practices in place, you can approach the behavioral preferences of the operators,” Rivenes said. “I think we’ve increased our tire life by about 40%. We are firm believers that if you are taking care of the tires, you will have taken care of the vehicle.”
Spring Creek loads coal primarily with one of two relatively new P&H 2300 coal shovels, a LeTourneau L1850 front-end loader or a Cat 5230 excavator. Some of these are also used in pre-stripping if necessary. They are also involved in various blending operations too. Operation-ally with the 80-ft seam, Spring Creek mines it in two lifts with the P&H 2300 electric shovels.
Mine engineers design the ramp itself to come into the pit at a level that’s about mid-seam. This way the shovel just mines off the top 40 to 50 ft depending on the pit. After traversing one pit length, a second ramp is then constructed down to the pit floor at the bottom of the coal seam and shovels remove the remaining coal. For safety considerations, the P&H 2300 shovels have a 55- ft maximum dig face. “In the BE 1570 pit we take about 50 ft off at first and then come back for the remaining 30 ft because that larger dragline cycles so much faster. Once the coal is uncovered, if you take more on top and less on bottom it allows the pit to cycle faster and there’s less coal remaining on that second time-critical pass,” said Walters.
What’s That in Your Coal Barn?
Historically, Spring Creek has run about 40% of its coal through a covered coal storage barn. Now that the tonnage has increased quite a bit, there is even greater use of what is perhaps the company’s most unique machine, a rather gothic looking Thyssen Krupp built traveling coal stacker/reclaimer. In continuous use since 1979, it’s the largest of its design. From support to support, the reclaimer is more than 150-ft long. It has a rotating barrel with buckets staggered along it that pick coal off the ground and cascade it onto a 72-inch conveyor running through the middle of the barrel. From there the coal goes to load-out. It uses articulating rakes to maintain the coal’s angle of repose and prevent it from sloughing down the barrel. “When the operator is sitting in the cab, they are controlling the reclaimer while watching the conveyor scale. Generally 4,000 tons per hour is the target for feeding,” said Mindham.
Blending to Meet Quality Specs
Similar to most northern PRB deposits, Spring Creek’s coal is high in sodium. “It’s not a constraint for us. We blend our coal if called upon and most of our export customers blend from various mines and sources. We’re basically competing directly against Indonesian coal, though we feel we have a significantly better product,” said Jones.
Coal quality is pretty consistent from top to bottom, but different regions of the mine have pockets of lower sodium. “We are able to render some low sodium coal for blending, but our basic product is 8% to 8.5% sodium. We are able to limit the sodium through a variety of in-pit blending techniques. We strategically mine with one of the draglines to allow us to have continuous access to the low sodium side of the pit. That’s how we sequence the Page dragline. The Bucyrus dragline remains in the standard product of the pit. But by varying the amount of low sodium coal we mine, we can blend it to spec for our customers,” said Jones.
“The importance of blending can’t be understated. Our Btu value is a unique aspect. We’re not just 8,800 Btu/lb like most PRB mines. Because of that, we have dozens of customers worldwide,” said Rivenes. Virtually free of mercury or chlorine in its coal, Spring Creek’s salable product is somewhat high in sodium, sometimes ranging up to 11%. “But we also have the ability to blend it down to normal characteristics around 4%. We do a lot of custom blends, keeping the Btu value high and taking the sodium down to specs,” said Jones.
Export Bottlenecks & Growth Markets
“The export market for Spring Creek is one growth area for us,” said Jones. In 2009, the mine shipped more than 2.5 million tons through Westshore Terminals with coal destined for several Korean and Asian customers. Currently, the majority of the mines’ production ships east, though they have several long-term customers in the Pacific Northwest too. “But until some additional power stations are built within a region that we can market to from along the BNSF northern corridor, we’re fairly well tapped-out, the export market is our opportunity for increased production,” said Jones.
Of course, the biggest single limit on expanding U.S. exports is the lack of port space on the West Coast. Westshore Terminals is the only large-scale coal port serving the growing Pacific Rim markets that takes any steam or utility grade coal. “There’s a limit to Westshore Terminal’s capacity and capability. They’re located on an island and have only so much room,” said Jones. First preference for limited space continues to go toward metallurgical coals which are sold at a significant premium.
Though the export business is developing slowly, it is growing each year. “We expect it to continue to be a dependable, reliable customer base. About 15% of our current production is exported to Asian customers. We do export a little into Canada proper too. We already have orders for roughly the same amount next year as well,” said Jones.
With the largest dedicated port space of any U.S. producer, Spring Creek has a substantial footprint with term
contracts. Westshore Terminals loads cape size vessels, among the largest ocean going ships in the world. Spring Creek first started to sell into the export market in the second half of 2008. Now they export an average of four trains per week.
The Transition to Cloud Peak Energy
Cloud Peak recently completed the transition from a Rio Tinto subsidiary to a free standing publicly held company. Despite the change in company size and name, all of the mines retained the same management teams as before and they are managed in the same manner. “From an operational standpoint, we had good practices prior to the spin-off and we maintain them now,” said Rivenes.
One major difference, of course, is that Cloud Peak is now a stand-alone company—very different from when it was a part of a massive global behemoth. “True, we no longer enjoy the same economies of scale that we used to, we’re still pretty big. Also, historically Rio Tinto did a great job of building safety into each aspect of its business. We’ve worked hard to carry that over into Cloud Peak Energy and maintain and improve on safety as well. We have a great safety record and we’re pretty darn proud of that,” said Rivenes.
Spring Creek’s safety program is an employee driven process. The Take 5 risk assessment program relies on the mine’s hourly employees to drive the safety culture. Each Monday morning at 6:30 a.m. the mine has a full safety meeting. The employees pick and chose the topics throughout the year. These run from training issues, near misses and what can be learned from them and how employees can comply with evolving rules and regulations.
In an effort to go above and beyond current MSHA requirements, operate as safely as possible and prevent any violations from being assessed, Spring Creek conducts a regular series of zone inspections where each manager is responsible for inspecting their work area. “They have to create an MSHA style audit and evaluation while taking on the role of MSHA inspectors, working to meet all the regulatory requirements and looking to find all potential violations and making sure we maintain compliance,” said Jones.
The emphasis on safety has paid off. Last year Spring Creek was recognized as a runner up for the prestigious Sentinels of Safety award for a Large Surface Mine.
Cloud Peak has also won several national Office of Surface Mining (OSM) reclamation awards including one last year for the mine’s work restoring rare colonies of Physaria didymocarpa variety lanata or Wooly Twin Pod plants to the region. These plants, part of the mustard family, grow close to the ground in scoria outcrops, producing yellow flowers and occasionally seeds. This contributes to the plant’s rarity. Following concerns stated by Montana regulators, Spring Creek voluntarily stepped up efforts to help conserve and grow the Wooly Twin Pods. With the help of an environmental consultant, Spring Creek transported individual plants located in the path of where mining activities would occur to special plant nursery locations around the mine. Employees also began collecting seeds that were sent to a commercial nursery. The plant has been able to rebound and their numbers on the mine site are increasing. In October 2009, both the OSM and the National Mining Association recognized the mine’s efforts by bestowing an Excellence in Surface Mining and Reclamation Award to Spring Creek.
Buchsbaum is a Denver-based freelance writer and photographer specializing in industrial subjects. He can be reached through his Web site at www.lmbphotography.com or by phone at 303-746-8172.
