Drilling to the core with Atlas Copco’s TH60DHNovember 20th, 2012 | Posted by in gray-four | TH60 | Waterwell Drills
Western Kentucky is known for its ample supply of coal. Although it might seem unusual to see an Atlas Copco TH60 water well rig at work in a coal mine, Armstrong Coal Company has found it valuable in starting up its two new mines.
Classified as a water well drill, Atlas Copco’s TH60DH (deep hole) can do much more. In fact, Atlas Copco’s entire range of water well products can be used in various applications, including geothermal, dewatering, degassing, uranium, leaching, coring, reverse circulation, potash drilling and exploration.
Armstrong Coal controls more than 300 million tons of proven and probable coal reserves in western Kentucky where they operate five mines, surface and underground.
The company became interested in the exploration and core drilling capabilities of the TH60DH drill rig when it started the expansion in 2011. Armstrong uses both rotation motors with a speed of 145 rpm to get their core samples and has found that is fast enough to get the quality they’re looking for.
Armstrong Director of Engineering Keith Brown said, “We’re doing exploration drilling to look for strata, normal mining strata, and we target some areas where we’re looking for strip faults—anomalies where there wouldn’t be good drilling.”
Core drilling and the exploration process are imperative to understanding different types of rock conditions, faults and abnormalities that will affect the design of the mine. Armstrong uses Atlas Copco core bits and drill steel.
Executive Vice President of Operations for Armstrong Coal Kenneth (Kenny) E. Allen described what they’re looking for in underground mines: “We look for the strata to determine the integrity and competency of the roof, and the quality of the coal seam.
“We analyze the coal for ash, sulfur, moisture and BTU content as well as perform a trace element analysis. It is important to know the constituents of the coal for marketing purposes,” Allen said. “We evaluate the floor material to help us size the pillars that support the mine—the softer the floor, the bigger the pillars. It’s all part of underground mining.”
Mining in the Bluegrass state
Sandstone, shale, and limestone are the most common rock formations in western Kentucky.
Approximately one month after the TH60DH arrived on site, Armstrong Coal drilled a continuous core for the new mine shaft with the TH60DH in Union County, Kentucky. Once completed, drillers will use the TH60DH to drill seven to eight water monitoring wells. This process involves drilling both shallow and deep wells and monitoring both surface water and deep water for at least six months prior to filing an application for a permit to mine.
Armstrong Coal also initiated exploratory drilling to target depths that could be used for the roof, floor, and seams at different localities around the location of their future mine. So far, drillers have been drilling to depths ranging between 270 feet to 1,500 feet, depending on the coal seam or slopes being analyzed.
As of August 2012, the TH60DH drilled more than 20,000 feet in Union County and logged more than 1,800 hours of drill time. According to Project Manager/Coordinator Steve Kane, the TH60DH is running at 95 to 96 percent availability and has had no major issues since it arrived.
Armstrong Coal was pleased with the versatility of the TH60DH. “The biggest benefit of having this rig is flexibility of doing things that we used to have to contract, which cost us a lot of money,” said Kane. “That drill has saved this company a bunch of money just from that standpoint. I’m very comfortable we can do anything we’re asked to do with it—monitor wells, holes for safe rooms, core drilling for underground, travel way and belt slopes. We can do it all.”
Using Atlas Copco PDC or tricone bits, the size of the holes varies from 9 to 12 ¼ inches, with consistent use of 3 ½-inch (89 mm) drill pipe. Armstrong Coal also used bits ranging from 5 ⅞ to 6 ⅛ inches for grouting once the casing was set. They drill through the casing, concrete, and then use a 4 5/8-inch (117 mm) bit to finish drilling the hole. They case with PVC mostly, but use steel when deeper than 1,000 feet.
Allen said the decision-making process to purchase an Atlas Copco TH60DH for use in a coal mine was simple: “We might be a little biased because we’ve had good results with our blasthole drills. We get good service. Atlas Copco has worked with us on issues that have come along on the drills.”
In fact, Armstrong Coal owns three Pit Viper 275 rotary blasthole drill rigs, three DML blasthole rigs and two ROC F9 top hammer drills. The company also uses Atlas Copco bits for a number of projects. “Everything we’ve got in our drilling stable, so to speak, is an Atlas Copco drill. Since we evaluated the deep hole drills, Atlas Copco seemed to have everything in the TH60 that we were looking for,” said Allen. “So it made sense to stay with the same group of people and the same company.”
The capabilities of the TH60DH had Armstrong Coal interested in more than brand loyalty. Allen said, “Many claimed they had the capabilities of doing what we wanted them to do and the TH60 seemed to stand out to us. We’re really pretty deep, taking core at 1,500 feet (460 m), and it’s pretty important to be able to get those cores where we need them.”
Armstrong Coal doesn’t need auxiliary air, even at those depths.
Kane and Atlas Copco salesman Paul Haynes worked closely together during the sales process. When Haynes visited Armstrong Coal in early 2011 to present the deep hole product range, Kane was adamant about having at least 50,000 lbf (220 kN) of pullback capacity. “We wanted something that had a lot of pullback power and with the TH60DH, of course we’ve got
70,000 lbf (310 kN) of pullback in case we get in trouble, and a lot of these other drills we looked at don’t have this capability,” said Kane. “We just felt that with the versatility, we could make the TH60 do what we needed to do with everything we were involved in.”
Haynes and fellow Atlas Copco Product Manager Frank Chickey were the two that led the training of the TH60DH. Kane said, “We got it in July, but these drillers had to go through a training process. Paul [Haynes] and Frank Chickey had a class for the drillers, and then we took the drill back in the parking lot and spent two, maybe three days of hands-on training.” According to Kane, the drill was unlike anything his two drillers had ever used, but they quickly caught on.
As of September 2012, the Armstrong West project has no definitive timeline. Drilling of exploratory holes continues to determine the best locale and structure for the new underground mine. Once all exploratory holes are completed for this project, the TH60DH will begin drilling safe-room holes, which are required for underground mines in case of disaster.
“We have to provide so many days of water, so many days of food, oxygen tanks, but also you have to have a surface hole coming all the way down and into that room so you can use it to drop communications, more food, more water,” said Kane. “As soon as the undergrounds get progressed enough to need those, then we’ll be putting those in, too.” Kane said it’s likely the TH60DH will be drilling a 10 ⅝-inch (270 mm) hole and setting 8-inch (203 mm) casing.
Kane is confident the TH60DH can handle the job no matter what project comes up for Armstrong Coal.
He said, “You can do so many things with it. You’re not handicapped. I’ve talked to different people around the country and we’ve been talking about equipment, primarily core drills and blasthole drills. And when I would tell them that we had a TH60DH water well drill, they said, ‘Well what are you going to do with it?’ And I said, ‘You don’t understand. This is what we have set this thing up to do—what we need it to do. We don’t call it a water well drill. It’s our multipurpose machine.’”