The shovel’s dipper or bucket holds more than 100 tons (90.7 t) of material — three scoopfuls and a 320-ton haul truck is ready to roll.
Big.
That little word captures the essence of Rio Tinto Kennecott's Bingham Canyon open pit mine. Situated a few miles southwest of Salt Lake City in Utah, the mine is big…as in one of the largest man-made excavations in the entire world, a hole so vast that astronauts can spot it from space. Big… as in the world's top copper mine, 20 million tons produced to date and counting. A big mine with big equipment to match — including six-story-tall electric shovels loading 320-ton-capacity haul trucks.
Dave Meador has the big job of managing operations at the Bingham Canyon. The Virginia Tech engineering graduate brings to the task a continental perspective, the continent being Australia where Meador worked for Rio Tinto for five years in a variety of capacities before moving to Bingham Canyon in 2013.
His arrival came eight months after a rock avalanche that, in keeping with the monumental character of the mine, was the largest non-volcanic landslide on record in North America. Some 150 million tons of rock and dirt rushed down the northeast side of the mine at speeds of up to 100 mph. To put the enormity of the slide in perspective, mine publicists say 150 million tons of dirt would cover New York City's Central Park 64 feet deep.
Surprisingly, Rio Tinto restored production within days of the disruptive slide. No loss of life occurred because geotechnical engineers had been monitoring the slope for months in anticipation of a slide. They moved people, equipment, and supplies from the anticipated path of the landslide — or so they believed.
It turned out the massive dislocation of rock and earth did not behave as predicted. It ran out across the floor farther than anyone foresaw. It not only, as expected, obliterated mining benches and haul roads, it changed a whole face of the mine and littered most of the bottom of the pit. Thirteen of the huge haul trucks that were thought to be parked out of harm's way were buried, as were three gigantic shovels and three drills. Several of the trucks eventually were dug out and restored to service.
With recovery operations still under way, Meador came north from Down Under and two years later became Bingham Canyon's manager. But if you want to find him, don't look for him in an office.
“I spend most of my time in the mine and in the concentrator [a separate ore processing facility five miles north of the pit],” he said. “I'm on the front line with the truck drivers and supervisors and shovel operators.”
He acknowledges that his enormous workplace, which has been synonymous with Kennecott corporation for more than 90 years, is an iconic hole in the ground, a vast bowl with long, terraced and gently descending slopes.
“Personally, I feel privileged to work in a place like this with the strong brand and the history it has. It is amazing how long Kennecott has safely operated the mine.”
Safety is a core value of Kennecott's business. No fatalities have been recorded at the Bingham Canyon mine since 1989, almost 30 years now. Accidents happen, of course, including two years ago when an earthen embankment gave way and sent one of the trucks rolling 300 ft. down an embankment. The driver walked away with bruises, one of the more dramatic seat belt endorsements.
“Fatalities are not something we accept in doing business,” Meador said.
Copper ore was discovered in the Oquirrh Mountains canyon by two brothers named Bingham just a year after Mormons entered the Salt Lake Valley with Brigham Young. But mining wasn't seriously pursued for 15 years and an open pit wasn't started until the end of the century. By 1923, Kennecott held a majority interest in the mine. Finally, Rio Tinto absorbed Kennecott in 1989 and invested some $2 billion to modernize the operation.
The pit has grown to be 2.75 mi. wide at the top and three-quarters of a mi. deep. It's big, in a word. All of that missing rock and soil has been pried loose and carted away using increasingly sophisticated methods. Mining and processing have evolved from primitive picks and shovels and horses and carts to rugged if rudimentary trucks and narrow-gauge railroads and finally to monstrous machines, some of them autonomous, and miles-long conveyor belts.
Rio Tinto has been in the vanguard of autonomous and distance-controlled machines for a decade. After the slide, the company employed remote-controlled bulldozers and loaders to clear the way for manned equipment to return safely to work. It employed an autonomous excavator, drill, and hydraulic shovel in the year following the slide. While some remote-controlled equipment still is utilized when safety is an issue, Meador said no autonomous equipment is operated there “in this current market. We have operated it in the past. We have experience with it and would use it again in areas where there might be risk of geological instability.”
Instead, the company relies on experienced drivers to pilot its house-sized trucks and swivel its hill-sized shovels. Drilling units also have operators in cabs, systematically boring holes for explosive charges that produce the rubble for those shovels.
Rio Tinto Kennecott officials decline to talk in specifics about brands of equipment, only acknowledging they operate a “mix” of makes. But reports through the years give glimpses of that mix. For example, after all that earth crashed down into the mine, the company scurried around to acquire a massive amount of equipment, including shovels, haul trucks, drills, dozers, excavators, wheel loaders and graders — 180 pieces of equipment. They were needed to remediate the mine and concurrently restart production.
Twenty-two haul trucks previously budgeted were acquired — Komatsu 930E models. The machines are direct descendants of the R.G. LeTourneau Haulpak. Each rigid, two-axle truck stands 24 ft. (7.3 m) high and can carry 320 tons (290 t) of material on tires more than 12 ft. (3.7 m) tall. Engine size? Upwards of 2,500 hp depending upon configuration. A 16-cylinder diesel engine fueled from a 1,200-gal. (4,542 L) tank is paired with electric wheel motors to power the gigantic vehicle from the bottom of the pit to a rock crusher at the upper lip of the mine.
In the days after the landslide, Rio Tinto diverted to the mine a new P&H 4100XPC electric rope shovel that originally was destined for another company operation. The shovel's dipper or bucket holds more than 100 tons (90.7 t) of material — three scoopfuls and a 320-ton haul truck is ready to roll. The 40-ft. (12 m)-tall machine's boom extends 70 ft. (21.3 m) in the air. Needless to say, the shovel was shipped to the mine in pieces and assembled in the pit.
The company also quickly acquired a Hitachi 5600 hydraulic shovel, a 590-ton (535 t) twin-engined machine. It also had to be assembled at the bottom of a secondary switch-back road, which became the primary access route for the pit after the slide. Trucking and sledding the shovel components to the lower assembly area was considered almost as big an achievement as procuring the machine. A Volvo A40 articulated truck was converted into a transport unit to haul some machine parts. Other new equipment bought and leased after the disaster included Caterpillar D11 bulldozers, the first of which was delivered three weeks after dust settled in the mine.
Today the mine has a fleet of 110 trucks, including Caterpillar and Komatsu haulers, most of them with Tier II engines. The trucks team up with eight electric and two hydraulic shovels. Each month, eight of the shovels trundle to a new location where rubble blasted from a 56-ft. (17 m)-high shelf awaits loading into trucks. The fractured rock is created from explosions triggered in 300 12-in. (30.5 cm)-diameter holes drilled daily along the shelf by a dozen drilling rigs. Some 500,000 tons (453,592 t) of ore and waste are hauled from the pit every 24 hours.
The mine operates 24/7, as conditions permit.
“It changes quite a bit, naturally, in winter time,” Meador said.
The Oquirrh Mountains mine site is, after all, across Salt Lake Valley from the Wasatch Range of the Rocky Mountains, where the Winter Olympics were held in 2002. The pit ranges from 8,000 ft. above sea level at the top to about 4,400 feet at the bottom. “So being at a high altitude, we have white-out conditions sometimes and our production profile looks a little bit different in winter. We are always doing the best we can, but there are times when we just need to pull back.”
Each shift, 100 of the trucks rumble up and down the 10-degree sloped roadway. The nearly 30-ft.-wide trucks pass one another on the 100-ft.-wide path. They travel at an average speed of 8 mph — a little faster than that coasting downhill when empty — with posted speed limits and engine governors dictating operational speeds.
“We limit the speed of the trucks for safety reasons,” Meador said.
Some 3,500 ft. of the roadway had to be rebuilt after the 2013 slide. From the shovel at the bottom to the crusher at the top, the journey is about 2 mi. long, a trip a haul truck can complete in 30 minutes or so. Not all the collected material is ore-bearing or otherwise of economic value, of course, so not all transported material ends up at the 200,000-tons-a-day crusher. Overburden is dumped in engineered and permitted locations.
The Rio Tinto Kennecott operation employs approximately 800 men and women at the mine, with 200 of them at work each shift along with a variable number of contractors, more than 100 in some cases. The company prides itself on the diversity of its workforce and the generational attachment of families to the operation. “If you go in the mine,” Meador said, “a number of team members can reach in their wallets and pull out photos of their grandfathers or great-grandfathers who worked here.”
Another 30 people are on the clock each shift maintaining equipment, either doing field maintenance or working in Kennecott's 19-bay truck shop. In 2011, a 100,000-ft. expansion updated the maintenance facility to accommodate a fleet of equipment that grows larger year by year.
“Our team does an excellent job from a maintenance standpoint. Our people have gotten really, really good at working efficiently,” Meador said. Augmenting the good shop work is the company's good working relationship with equipment-makers. “We are fortunate that we can go to manufacturers and talk about things we are experiencing with the equipment. We are able to prevent a lot of issues from developing.”
The open pit itself is the core of the operation, but it is only a starting place for Rio Tinto's Utah mining operation. Crushed rock carried from the pit leaves the mine on a conveyor system that carries basketball-sized rubble 5 mi. north — including 3 mi. through a tunnel — to a concentrator.
There, valuable minerals are separated out and ground into fine powder before being conveyed as a liquid concentrate 17 mi. farther north. In several subsequent steps, the copper ore is filtered and smelted — another monumental statistic: the smelter stack is the tallest structure in Utah, just shorter than the Empire State building — before being cast and refined. On an average day, ten rail cars, each containing 185,000 lbs. of virtually pure copper sheeting, roll away to customers.
The rest of the story is about the company's environmental efforts, including creation of a 3,000 acre Kennecott Inland Sea Shorebird Reserve, an area set aside to mitigate 1,000 acres of wetlands encroached upon by an expanded Kennecott tailing impoundment area. Also created by the company is Daybreak, a 4,100-acre master-planned community built on land impacted by the mine over the decades. It features open space, trails, energy-efficient homes and LEED-certified buildings, one of which is the Rio Tinto Kennecott headquarters. On another environmental front, the company reached an agreement last fall with Rocky Mountain Power to decommission the company's three coal-fired powerplants, though they were operated only during non-winter months.
Copper is the main product of the Bingham Canyon mine, of course, but gold, silver, molybdenum and sulfuric acid are produced as well. Commercial uses for the mine's production include computers, cell phones and solar panels.
“There is great pride here in how we are helping push human progress,” Meador said. “We are mining materials that at the end of the day are making a difference — and we are doing so safely and with respect for the environment.”
CEG
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