For most quarry equipment, the value of technological progress is measured in tons — the number of additional tph new machinery can load, haul, crush or classify. The criterion for judging the performance of new drilling equipment, however, is feet — additional feet drilled per shift, the drill's penetration rate in typical or tough conditions, and the number of feet drilled during the life of a drill bit.

As the industry demands higher drilling performance, manufacturers continue to develop crawler and truck-mounted rigs with increased compressor power, better mobility and improved ergonomic features. In addition to this, they have not ignored the bottom line: more efficient rock drills that take advantage of the rigs' capabilities to provide the additional footage expected from customers.

All of the major types of production drilling techniques — rotary, top hammer (TH) and down-the-hole (DTH) hammer — can and have been used in quarries. However, much of the current technological focus is on tweaking DTH and TH drill design to optimize performance in the medium-sized rig range normally used to sink 3½- to 7-in.-diameter blastholes.

Interestingly, much of the impetus for product improvement in the DTH sector has come from the gold mining industry, where high production demands, close attention to ore-grade control and stringent sampling requirements generally dictate smaller, tight blast patterns and shorter bench heights. These characteristics also are common in quarry blasting and can be accommodated by mid-range drill rigs. Meanwhile, top-hammer manufacturers are introducing products designed to maximize the economy and flexibility traditionally provided by TH drill rigs.

To satisfy the wide range of drilling conditions, production targets and equipment budgets, most major manufacturers now offer product lines for both DTH and TH operations.

Furukawa Rock Drill, for example, has developed two new drill-rig series: one for DTH and one for TH drilling. The company says these offer low cost-of-operation and a quiet, dust-free operator environment. Furukawa's DCR-23 DTH rig, designed for drilling 5½- to 6½-in. holes, is a fully self-contained, mobile crawler equipped with a high-performance compressor providing output capable of powering any DTH hammer. The drill's power pack is said to deliver low fuel consumption along with full 350-psi operating pressure, while operating on a highly mobile and stable crawler.

Furukawa's HCR-1500 hydraulic top-hammer rig features a new 700 series drifter drill capable of operating in the 4- to 5½-in.-hole range, using standard T-51 drill rods. This drill features a newly developed Dual-Dampened Wedge drifter design, which Furukawa says will lower drill-tool consumption and often can more than triple the life of T-51 shank rods. Also, the rig uses a new carousel-type rod changer and single-lever drilling controls to increase productivity. A drilling control system automatically adjusts the impact, feed, rotation and dampening pressures to match the rock conditions.

Both series come standard with sound-proofed, ergonomically designed operator cabs and maintenance-friendly access to lubrication points and filters. Gull-wing doors on the 700 series provide ease of entry.

The Reedrill Division of Metso Minerals recently made available its SD250 hydraulic track drill rig, fitted with a new HPR45 top-hammer drill that has undergone more than two years of field testing. The SD250 is designed to work in the 2½- to 3½-in.-diameter hole-size range. It is powered by a 174-bhp engine that consumes less than 6 gallons of fuel per hour, allowing more than 13 hours of operation without refueling. The SD250 is equipped with an air compressor rated at 250 cfm free air delivery. The coolers are mounted side-by-side for cooling efficiency and easy cleaning.

The drill's Duraquip dust control system consists of a power-operated pick-up pot, a precleaner with a dropout box and a dust collector. The collector fits within the profile of the machine, resulting in an operating and shipping width less than 8 ft; this allows the drill to be transported in a container. The collector is mounted on a swing post that can be moved for access to the hydraulic valves. The valves have built-in test ports for diagnostics in the field.

The HPR45 hydraulic rock drill, according to Reedrill, offers as much as 20 kW of power with fewer total parts than competing drills. The increased power, the company says, improves penetration rates and overall production. The drill's relatively simple design incorporates robust components that increase service life and provide easy service and maintenance; the drill can be serviced in the field. The HPR45 is mounted on a new feed system with a cylinder/cable feed arrangement for smooth operation and easy adjustment.

The SD250 is equipped with Reedrill's SmartDrill drilling system, featuring self-adjusting feed-force logic to extend the service life of consumables. The drill's cab offers high operator visibility, noise abatement to 78dBA and multi-function joystick controls. It can be equipped with remote tram and boom controls with extension cord for tramming in difficult terrain. This feature, combined with the drill's 23-in. ground clearance, makes it suitable for pioneering work. The SD 250 is available in cab and noncab versions.

Going to the show

The Sandvik Group, which acquired Austrian drillmaker BPI in May 2000, plans to introduce the Titon 500, a mid-range crawler drill, at this year's CONEXPO-CON/AGG exhibit. The drill will be built by BPI and marketed in North America through Sandvik's Tamrock division.

The Titon 500 is a diesel-powered, self-contained rig designed for DTH drilling in the mining, quarry and construction industries. The drill features a heated and air-conditioned operator's cabin, a robust boom with 31½ in. of telescopic movement, a dry dust collector with hydraulically controlled suction hood and fan, and a hydraulic pipe changer with six-pipe capacity.

Designed for drilling 4- to 6-in.-diameter holes as deep as 115 ft, it is powered by a 365-hp, six-cylinder Caterpillar C10 engine. It also is equipped with a GHH CF Series rotary screw-type air compressor that provides 776 cfm at 348 psi. Standard equipment includes compressor controls for hole collaring which, when activated, decrease air volume and pressure. Also standard is an air-line lubrication system for flushing the head, drill pipes and DTH hammer with system controls in the cabin.

The undercarriage comprises a heavy-duty excavator-type steel frame mounted on two track assemblies and a track oscillation shaft. The independently oscillating tracks are fitted with chain-linked, triple-bar grouser plates and chain guides. The track chains are tensioned by a hydraulic grease cylinder on the idler wheel.

Available accessories include a foam/water injection system, electric fuel and hydraulic fluid fill pumps, single grouser plates for rough terrain, electronic angle indicator, compressor anti-frost system and a tow coupling.

After introducing the 431-hp ROC L8 DTH crawler drill at MINExpo 2000, Atlas Copco followed up by showcasing the ROC L6 DTH drill at BAUMA 2001. The L6 is aimed at customers who require a heavy-duty unit to drill 3½- to 5½-in.-diameter holes. The company also began marketing the ROC L7, a hydraulic rig designed to work with Atlas Copco's 4050 top-hammer drill.

The ROC L8 is a flexible rig designed for presplitting and production drilling in hard rock, with hole capacity up to 6-in. diameter and 177 ft deep in quarries and open pit mines. The L8 is powered by a 431-hp, water-cooled and turbocharged Cat 3196 ATAAC engine. It is also equipped with an Atlas Copco compressor that provides free air delivery of 858 cfm to power a variety of DTH hammer sizes. A double drill-tube guide helps to achieve straight holes with easy collaring.

Like the larger L8, the ROC L6's high-capacity air compressor is capable of providing hole depths to 115 ft using Secoroc's COP 34, COP 44 and COP 54 hammers. According to the company, penetration rates during field-test drilling of the L6 have reached more than a yard per minute in basalt, using a 3½-in. ballistic bit.

From MINExpo

Ingersoll-Rand introduced two new 600 series crawler drills at MINExpo 2000. Its ECM-660 drill sinks holes from 3- to 4½-in. diameter and is equipped with a Montabert HC120 hydraulic drifter drill. Hole cleaning has been enhanced with a GHH-Rand air compressor that delivers 310 cfm at 140 psi and a high-vacuum dust collector.

A 237-hp, aftercooled and turbocharged Cummins 6CTA8.3 engine powers the ECM-660. The engine maintains fuel economy with an automatic throttle control that lowers rpm during non-drilling operations, saving as much as 15% in fuel costs. The drill's Strata-Sense Drilling Automatics constantly monitor and hydraulically adjust the drilling functions for hole straightness, accessory life and performance.

I-R's model ECM-680 crawler can drill 4- to 5-in. diameter holes and features a Montabert HC150 hydraulic drifter with a trapezoidal piston design that is said to deliver maximum impact energy to the rock. Higher oil flow and elevated drifter efficiency have increased drifter horsepower by 20% versus the previous model, according to the company. The ECM-680 is equipped with a compressor that delivers 370 cfm at 150 psi, and is powered by a 260-hp aftercooled, turbocharged Cummins 6CTA8.3 engine.

At the other end of the drilling application spectrum is Tramac Corp.'s line of excavator-mounted rock drills, designed for construction work or mine sites with light blasting requirements. Tramac's latest product is the CPA, a top-hammer unit offered in two versions. The basic CPA 225 has a Montabert HC40 drifter and can sink holes diameters from 1½- to 3-in. The larger Xtend model can be equipped with a greater selection of options including Montabert HC105 or HC150 drifters, capable of drilling 3-in. to 4½-in.-diameter holes.

Tramac claims that, with the CPA's onboard hydraulics and controls, the drill can be attached and operating on an excavator fitted with a quick-attach bucket system and quick-disconnect hydraulic lines in less than 10 minutes. The Montabert drifter, featuring Drilling Automatics and Rock Reader Technology, senses rock conditions as the hole advances, and automatically makes the necessary corrections to rotation, feed and percussion pressure, and feed speed forward and backward. A Rebound Energy Recovery Valve matches blow energy to the rock hardness.

The CPA also has a reverse percussion option that assists in extracting drill strings in fractured and unconsolidated rock.

According to Tramac, all drilling functions are monitored and adjusted hydraulically. Flow and pressure adjustments are automatic, progressive, and stepless, and the unit's patented drilling system operates without need of microprocessors. The CPA also has a choice of feed sizes in 24-ft and 14-ft pipe configurations, rod changing by carousel or single-rod adder, and remote control capability for operation in or out of the excavator cab.

With pressure on rock producers to crush more stone for less dollars, drill vendors will be looking to go the extra mile. But for producers, sometimes a few extra feet is good enough.

Pushing the Drill Technology Envelope

One of the most effective advances in drill technology has been the introduction of onboard intelligent drilling systems to the medium-sized rock drills commonly used in quarry operations.

All of the new drills described in the accompanying article provide some form of automatic control. These controls adjust drill operating parameters for current rock conditions by changing feed pressure, feed/rotation speed and other functions to reduce stress and wear on drill components and improve penetration rates.

The importance of efficient drilling is such that drill suppliers and rock producers will continue to evaluate new ideas to improve performance and reduce costs. Rock-breaking methods ranging from high-pressure waterjets to high-intensity electrical impulses have been investigated during the past 20 to 30 years as possible alternatives to mechanical drilling. But these remain largely an interesting footnote on the drill technology time line due to their uneconomically high energy requirements.

On a more practical basis, however, drill companies are focusing on certain basic elements of drill design and application that hold the potential for cost savings and higher efficiency. These concepts range from a search for a more efficient power source for drills to more effective operator training using equipment simulators.

Hilti Corp. says it is testing what is described as the “first electric rock drill to be used in mining” at a South African mine. Hilti, which produces hand-held drills for construction and demolition jobs, says the new rotary hammer drill is undergoing field tests after a three-year study of the potential market for such a unit in North and South America, Australia and South Africa. Hilti will test the drills at a South African mine during the first half of this year.

Although technical details of the drill weren't available, a Hilti spokesman says that an electric drill can provide several advantages over pneumatic drills:

• Quieter operation and less vibration;
• Reduced energy consumption because electricity is a more efficient power source than compressed air; and
• Cost savings from eliminating compressed air systems.

Earlier this year, Atlas Copco Construction and Mining North America partnered with Simlog, a Montreal-based simulator developer, to offer customers after-market, simulator-based training for Atlas Copco drilling equipment. Although this simulator was developed specifically to train operators on multi-boom jumbo rigs typically used in underground mining and tunneling, the simulation software and hardware systems can be applied to develop almost any type of drill simulator required.

The simulator, which incorporates standard drill controls and three-dimensional graphics showing the boom components and drill face, provides a means to measure operator performance criteria necessary for efficient drilling operations.

Blaine Vatcher, technical services and training manager for Atlas Copco, says “this type of training tool is needed because the level of technology being used [in drill jumbos] demands a higher level of knowledge and quality control from operators. With the simulator we can control the situation and monitor performance, then provide feedback to improve the operator performance.”

There are certain obvious advantages to simulator training — for example, vital production equipment doesn't have to be taken out of service for training sessions.

But as Paul Freedman of Simlog points out, acceptance of simulator-based training has been hindered by the difficulty in quantifying the financial benefits of such training. Although the jumbo simulator has not been in service long enough to measure actual training benefits, he says that Simlog previously developed a logging-machine simulator. In a year of simulator-based training involving about 50 students, the trainees were estimated to be 10% to 15% more productive as a result of their simulator-based preparation. Equipment maintenance attributed to training activities dropped by 25%.
— Russell A. Carter