An operator stands outside the cabin of a large rotary blasthole drill. (Photo courtesy of Atlas Copco)

By Donna Schmidt, Field Editor

Drilling is a vital aspect of surface mine production that does not always get the same level of respect as the draglines, shovels and trucks moving the blasted overburden. The performance of a mine’s drilling and blasting program, however, affects the overall performance of the overburden removal process. Drilling also yields immediate clues about the rock formation and the precision with which the blastholes are drilled directly impacts the effectiveness of the blast. So it’s important that drillers understand their role in the process and new tools are allowing mine operators to examine the drill’s performance and better train operators.

Rotary blasthole drill rigs consume a lot of fuel. Punching 12-in. holes, 65 ft deep or more through rock requires power. The rotary action and the downward pressure on the bit consumes power and so does the compressor system, which is used to bail the cuttings from the hole. While the optimum amount of air pressure is an often debated question among drillers, running the compressor while tramming from hole-to-hole is a waste of energy. New tools have been developed to cut those energy requirements and save on fuel costs and large coal operations in the western U.S. are putting them to the test.

Similar to all aspects of mining, safety is a major concern around drilling operations. Most of those safety concerns arise from the rotating equipment involved in the drilling process. Many mines are working with original equipment manufacturers (OEMs), such as Atlas Copco and Sandvik, and other service providers to improve safety.

From a product technology and research perspective, it is clear that Atlas Copco has been quite productive at the research and development table, and much of this work has been focused on overall efficiency and, just as crucial, even greater safety for workers.

Many of the incidents with injury that occur to workers working with a surface drill rig involve, at least in some part, moving parts. Responding to that, the company introduced a protective guard to offer operators added protection.

“At Atlas Copco, safety is a priority issue and the company is committed to ensuring that its products are as safe as possible [and] in line with this policy, it has now taken steps to provide added protection for rock drillers by launching a protective guard for its surface drill rigs,” the company said. “This concept targets the potential risk of getting too close to the rotating drill rod while the drill rig is in operation.”

The slim line guard does not impair visibility, nor does it interfere with the drilling operation or the rig’s performance. When the unit is in need of service, the guard can be easily opened using a standard wrench, and the lower rubber portion of the guard provides flexibility when drilling in different positions or in difficult formations.

The guard incorporates an extension on one side of the boom to give extra protection to the operator while the rig booms for toe-hole drilling are in the horizontal position. Parallel with this, the boom systems have been strengthened to accommodate the extra weight the guard adds.

Atlas Copco has also had its eye on the equipment front over the last couple of years, introducing both the DM-M3 and the Pit Viper 311.

Tackling the need for deep drilling of overburden is the Atlas Copco DM-M3, a crawler-mounted, hydraulic tophead drive multipass rotary rig.

The unit has been designed for hole diameters between 9 7/8 in. and 12 7/32 in., and features the hydraulic tophead and variable displacement pumps to allow for an endless selection of rotation speeds and variable torque values. Single pass depth is 37 ft.

The DM-M3 also has a high-strength cable feed system with automatic cable tensioning, and hydraulic double-acting feed cylinders, with a tower that can be moved up or down quickly with a full complement of drill pipe in the carousel and under the rotary head.

Tower pinning and pipe changing on the unit can be performed remotely from the cab, and optional angle drilling package can permit tower positioning up to a maximum of 30˚ from the vertical.

The Atlas Copco DM-M3, weighing in at 230,000 lb, has an onboard depth capability of 200 ft using 10 3/4-in. diameter drill pipe and up to 240 ft using 8 5/8-in. diameter drill pipe with a five-rod carousel. Using a patented hydrostatic, closed-loop system that acts through twin, double-rod hydraulic cylinders and cable, the machine’s weight on bit is rated at 90,000 lbf.

Credited with the notable ability to drill a 65-ft clean hole of 9 in. to 12.25 in. in a single pass and add greater productivity for operations is Atlas Copco’s Pit Viper 311. The unit features a bit load capacity of 110,000 lb and the ability to yield a higher drilling efficiency — up to 25% when drilling in soft material, according to officials — by completely eliminating rod change time.

The newest addition to the Pit Viper lineup has incorporated new designs for ergonomics and visibility as well as cost savings, and also has the line’s Rig Control System (RCS) technology for greater accuracy and better serviceability.

“RCS provides a number of safety and interlock features, as well as a foundation to build in more technology options if desired in the future,” the company said, noting that while RCS is standard, there are three optional RCS packages available including AutoLevel, Auto-Drill, high precision GPS and teleremote control.

With the RCS system, an operation can add new functionality/options at a later point in time as needed, and without doing a major rebuild to the machine.

The PV-311 also has a dual-feed system with dual hydraulic feed cylinders that raise and lower the rotary head smoothly and positively by way of cables for both pulldown and pullback. Also, large diameter sheaves are designed to further increase cable life.

“The PV-311 increases productivity through increased tramming, feed, and retract speeds, in addition to increasing the rates of the non-value added functions of the machine such as setting up,” Atlas Copco designers said. “We have reduced the amount of downtime for preventive maintenance by up to 50% with the introduction of the centralized filter rack and ground level service interface where all fluids can be filled, drained or sampled.”

Ask anyone in the surface mining sector, coal or otherwise, and both the environment and worker safety rank among the top everyday priorities at operations. With those benefits and more in mind, Sandvik released its Compressor Management System (CMS) and began placing it on its own blasthole drill rigs beginning in March 2011 and have since provided many add-on retrofit kits to enable other machines the biggest advantages of CMS.

What advantages, exactly? A reduction in energy, for one, as well as operating cost. The environmental impact is significantly reduced by the system’s engine load reductions when not drilling, as well as permitting the compressor to run at full volume only when it is needed.

A Sandvik DR580 simulator by ThoroughTec.
A Sandvik DR580 simulator by ThoroughTec.

This drastically cuts diesel consumption during setup, tramming and pipe handling, according to Sandvik Vice President of rotary and HP DTH drilling Ken Stapylton.

“Less than 40% of the energy given to a drill’s compressor is used for breaking rock, which is why a management system can have such a positive financial impact,” he said.

Also, machines without CMS have inherent issues at startup and shutdown. In the former, a starter motor cranks both engine and compressor and the compressor produces air immediately and builds to full pressure, stalling the engine, and engine startup can be difficult and require “bleeding” the receiver tank before trying again, and sometimes again after that.

With CMS, intelligent starting process minimizes startup compressor load and there is no air produced until the engine reaches idling speed (or 1,190 RPM). The unit also builds 3.5–4.5 bar/50-65 psig of pressure in the receiver tan, which activates the evacuation pump and off-loads the compressor. Air pressure in the receiver tank lubricates the compressor without a parasitic load.

At shutdown, without CMS, the rig’s compressor is loaded by pressure in the receiver and engine load is maintained at as much as 60%. Engine EGT does not drop (typically 600°C/1,112°F), and turbo chargers, piston crowns and engine oil do not cool down.

Post-CMS placement, the main compressor is evacuated by the secondary compressor and the compressor is isolated from the receiver tank; moreover, engine parasitic load drops to less than 10% and the unit’s inlet butterfly is held closed. EGT drops to less than 300°C /572°F and turbo chargers, piston crowns and oil all cool to below manufacturer recommendations.

When the company originally tested its system on a DR460 rotary drill at a coal mine in Australia’s Hunter Valley in 2010, the initial reported fuel savings totaled 33%.

It was that success that led it to team with Cloud Peak Energy just two years later, proposing the Powder River Basin producer with an offer that they could not refuse: a one-time performance guarantee that virtually eliminated the operator’s risk by testing a retrofit CMS on its then-14-year-old, 60,000-hour D75KS at the Cordero Rojo complex — the mine’s oldest drill.

The testing, it said, would reduce fuel consumption by an estimated 23%, which would tie in an increase in hole width to 11.25 in./28.6 cm.

According to Sandvik, the performance guarantee was simple — if the system delivered at least 90% of the fuel savings it proposed, Cloud Peak Energy would buy it. If the CMS underperformed, Sandvik would remove it from the unit at no cost.

“We were confident offering the guarantee, based on our experience and knowledge developed over the past few years with the CMS,” said Tab Siegrist, Sandvik product support manager for surface drilling.

In its testing, the Engine Control Module revealed the drill used 22.9 gallons of fuel per hour prior to the installation of the CMS. After running the system for five weeks, it used only 16.9 gallons per hour — a drop of 26%.

“Drill engines are loaded all the time,” said Mark Gilbertson, Cloud Peak Energy director of asset management. “We work on a lot of different kinds of machinery, and drills have always been something that sound like the engine is suffering because it just never gets unloaded. This CMS is a reasonable way to take that load off the engine.”

The system also enabled Cordero Rojo to shut down the D75KS when it didn’t need to be running, an option previously unavailable to the mine during Wyoming’s coldest winter months.

In addition to curbing fuel consumption, Sandvik said that the CMS offered the producer the added benefits related to a reduced engine load — including longer engine and compressor life, higher drill utilization and lower service costs from extended service intervals.

“We see Cloud Peak Energy’s investment in this new technology as a forward step to not only achieve improvements in the operational costs of drilling equipment but also to address the increasing concerns we all face about the environmental impact of mining operations,” Siegrist said, noting that in Cordero Rojo’s case, hundreds of metric tons of carbon emission can be saved on an annual basis.

“There is often a cost to being leaders in conservation and environmental excellence, but some of the efforts wind up being positive financial decisions as well,” Gilbertson said of the teaming, calling the move a “a pretty easy decision” to benefit the environment while also paying for itself quickly.

In the time since, Cloud Peak Energy purchased two new Sandvik drills with CMS installed: a D75KS for Cordero Rojo and a D90KS for its Spring Creek operation in Montana to replace its retired Sandvik Driltech D40KS and D45KS machines.

Gilbertson said the trial’s success “was a significant factor” in its decision to purchase.

“The CMS on the trial drill continues to be consistently in the range of 25 to 27%,” he said. “We’re quite pleased with it.”

Sandvik has also continued its commitment to safety; in November of last year, it announced it had partnered with Barrick to improve drill safety in a collaboration that brought them together at a gold operation in Nevada.

The teaming involved the testing of a prototype of the Sandvik DR461i rotary drill rig at Barrick Gold’s Cortez mine. As part of the testing process, Sandvik Mining engineers collaborated with Barrick Gold equipment operators to evaluate the new drill’s safety features and recommend enhancements before the product launches globally.

The results of this process, formally known as EMESRT Design Evaluation for EME Procurement (EDEEP), were then presented to the industry at the recently held Global Health and Safety Excellence in Mining Forum in Las Vegas.

“Safety is our top priority at Sandvik, and we want to ensure all individuals who operate or maintain our equipment are safe at all times,” said Darlene Dutcher, product safety manager for surface drills.

“The EDEEP program is instrumental in allowing us to see through the eyes of our customers to identify potential risks that are either environmentally based or related to personnel safety. It is a critical step in our product development and testing process and a practice we’ll continue to implement with our customers.”

As part of the EDEEP program, Barrick Gold operators and maintenance personnel conducted a risk-assessment of tasks required of the Sandvik DR461i rig. They ran the drill in day-to-day operations and as each step of the drilling process was completed, they identified potential hazards from their perspective. This two-way communication enhances current drilling operations as well as new product

“During the EDEEP activities, our operators found a lot of value in the direct interaction with the Sandvik engineers and being able to ask them why certain components were designed the way they were,” said Kevin White, Barrick Gold Cortez drill and blast supervisor. “At the end of the day, we were grateful to have the opportunity to share our feedback with Sandvik and to see their commitment to delivering the best product possible.”

Of course, the results of the collaboration are broad to the greater surface mining industry; in fact, the surface drilling team at Sandvik used the results to make changes to the drill before it launches and is also using the information in new product development activities.

In many cases, finding the benefits of efficient blasthole drilling practices comes simply from determining the inefficiencies — not just at the point of drilling but all stages of the process.

According to Leica Geosystems’ Dr. Brandon Lilly, mines across all of the industry’s commodities do not place sufficient emphasis on generating an efficient drill-and-blast process. As a result, downstream complications can, and at times do, occur.

There are several different areas that contribute to blasting inefficiencies, including irregular hole placement that can cause poor fragmentation, resulting in difficult digging for the loading equipment, and inaccurate depths resulting in uneven benches.

Leica’s J2drill provides feedback to the operator and mine staff in real time via an onboard cabin computer and also at the mine’s command center.
Leica’s J2drill provides feedback to the operator and mine staff in real time via an onboard cabin computer and also at the mine’s command center.

Additionally, holes that are over-drilled into the coal seam can result in dilution of material into the coal, and a misunderstanding of how hard the ground is can lead to a poor choice of explosive product for a particular blast.

While many varying approaches have been attempted to improve this, in many cases while also reining in costs, Leica said all aspects of the comprehensive process — from design accuracy to accurate positioning, increased safety, tracking consumables, proper time utilization, optimizing blasting methods and more — should be looked at to determine where benefits can be gained.

Now part of the Hexagon Group, Leica — with origins dating back nearly two centuries — has significantly evolved. The company’s growth over the last several years reflects that, from the acquisitions of Mintec and SAFEmine just last year to Surveyors Service Co. in 2008 and Loyola Enterprises and Technodigit the following year. In fact, in the time since the last MINExpo in 2012, a total of 17 global companies have come under its wing.

Central to that all-encompassing effort to help mines improve all faces of blasting operations, Leica developed the high-precision guidance product Leica J2drill, which provides feedback to the operator and mine staff in real time via an onboard cabin computer and system at the mine’s command center.

In addition to the more obvious advantages of such technology, primarily navigation, J2drill can also provide data on detected coal seams and thicknesses as well as track the use of consumables, such as bits, which in turn help the user save money and unnecessary downtime.

For mines going deeper with more complex orebodies — which today can account for a lot of operations — there is JPS, or Jigsaw Positioning System. It offers satellite augmentation when satellite availability is poor or diluted, much in the way a signal booster might do for a cell phone, but in a much larger and grander scale.

In fact, Leica noted, JPS has offered mines 100% satellite availability right up to the pit highwalls.

Also integrating well with the company’s other systems is MineSight Axis, which manages grade control, drill and blast and reconciliation for the optimization of material classification.

The software, highly scalable, can save up to three hours daily for operations and offers blasthole information from various data sources that can be manipulated with compositing, coding, interpolation or user calculations.

Blast patterns can also be designed in MineSight 3D along with stored blasthole geometry from MineSight Torque, where it can be attributed with explosive, drilling, mining cut and as-drilled information.

Scripting background is not needed; the software possesses an intuitive user interface and easy-to-follow workflow process. It also offers a streamlined method for calculating reserves for daily and monthly reconciliation.

According to MineSight, when Freeport-McMoRan-Morenci invested in MineSight Axis for its imaging and drill fleet management technology improvements, the system helped it to manage and analyze data and save more than $120 million in horizontal accuracy over three years.

Looking ahead, the company is looking to make that wheel even bigger; it is currently polishing its Hexagon Mining Athena business intelligence software. Slated for release in the near future, the larger system will allow remote access of data while also adding much greater versatility.

One official called their approach to the blasthole drilling a “holistic perspective,” noting that while no operation is required to incorporate its entire line of products, each plays a role in key areas for mining operations. From the hub to the spokes of the company’s wheel, it has the needed solution for every drilling issue from mine to mill.

“There are many opportunities to improve the efficiency of the drill-and-blast process using technology,” Lilly said. “By using high-precision guidance systems, drill-and-blast engineers are able to carry out tasks to plan, making sure they make the correct decisions at the first time of asking.”

With the vitality and complexity of blasthole drill rigs in the surface mining space, training simulator provider ThoroughTec Simulation has understandably been responding to a growing demand for its Cybermine operation simulation technology.

“With mine site safety and productivity being of paramount importance, these training simulators are vital tools in ensuring that operators know exactly how to operate the rig safely and efficiently without the mine having to take an actual rig out of production for too long,” the company said, noting that the increased availability of the drill is vital, as it aids cost efficiencies.

F2 4 CYBERMINE-4-Surface-Base-Unit
Inside a ThoroughTec Cybermine simulator unit.

According to Vice President of Research and Development Richard Bellengère, it is crucial to have a skilled operator on these complex units to ensure safety and efficiency.

“Besides learning how to accurately position the rig and the mast, the operator needs to know how to change rods on the carousel and drill at the right angle and pressure so the rods and drill bit don’t burn up or break,” adding that controlling the load on the rod and bit is vital.

Additionally, because blasthole drill rig operators often must work with an outside assistant, ThoroughTec said it has considered this by creating an artificially intelligent mine worker that works in the 3-D virtual world while the operator is training in the simulated cab.

Over the last year, ThoroughTec has developed a significant number of Cybermine simulator cabs for blasthole drill rigs globally. These include five different models from three different OEMs: Atlas Copco, CAT and Sandvik. Some of these were for two very large clients, such as Kazakhstan’s biggest copper miner, which ordered a Sandvik D55SP simulator, and a major manganese producer in South Africa, which ordered two drill simulators for the Atlas Copco Pit Viper 271 and Sandvik DR580.

“When in the market for a blasthole drill rig training simulator, it’s important to consider the supplier’s experience in building reliable systems, which ThoroughTec has been doing for years,” Bellengère said. “Our first blasthole drill rig simulator was a P&H 250XPC for a diamond mine in South Africa nearly 10 years ago.”

Since that time, the company has made significant progress with their in-house blasthole rig simulator development and, of course, providing the results to mines worldwide.

One currently on its way to the operator client: a Cat MD-6290 simulator to Swakop Uranium’s Husab mine in Namibia, one of the biggest uranium mining projects in the world, which will pair well with its recently obtained Cat MD-6640 simulator.

According to the mine’s training manager, Ferdy Schwartz, the project needs to train many novice operators for dozers, haul trucks, shovels and, of course, blasthole drill rigs. Their plan is to provide five weeks on a simulator, five weeks in the field, and five additional weeks on the simulator; annual refreshers using their new technology is also on the agenda.

“[ThoroughTec] got all the drill basics right along with accurately simulating the finer details such as percussion and drill length,” Schwartz said. “They did their homework.”

Simulated cabs from various OEMs that have been or are in the process of being developed include ADTs, bolters (including meshing and scaling), continuous miners, dozers, draglines, excavators, graders, haul trucks, LHDs, locomotives, personnel carriers, scalers, shotcrete sprayers, shovels, shuttle cars, surface and underground drill rigs, and wheel loaders.