Efficient blasthole drilling can lower the cost of blasting overburden and ore in open pit mines. Low drilling costs mean larger pits and higher strip ratios can be justified.
At least eight drill rig manufacturers supply blasthole drills to the Canadian market. All have made changes recently to designs that have evolved over the past 40 years.
Atlas Copco
Atlas Copco does not manufacture machines in the big-drill class of rotary drills. Howewer, it is a contender in the smaller drill hole field, where diameters reach a maximum 6-1/2 inches. The company offers three different series of rotary open pit drill rigs.
The first is the ROC722-HC series, which comes with or without cabs and with single booms, folding booms and extension booms. This series can drill holes as small as 1-7/8 inches and as large as four inches. The ROC 722HC series is crawler-mounted and equipped with Atlas Copco’s COP 1238 hydraulic rock drills.
Atlas Copco’s ROC 812HCS series of cab-outfitted, all-hydraulic drills can produce holes ranging from 2-1/2 to five inches. These compact rigs are noted for their quick setups and total independence, due to an on-board compressor.
Finally, the company offers its ROC936HC series drill for hole ranges of 4-1/2 to 6-1/2 inches. This single-model series is a fully independent, mechanized, diesel-hydraulic crawler rig designed for larger operations that require up to 12,000 tons per shift. The machine can be fitted with three different Altas Copco down-the-hole hammers. The unit is powered by a V12 Deutz diesel producing 316 kw at 2,300 r.p.m.
Bucyrus-Erie
Bucyrus-Erie built its first rotary drill in 1952 and has since placed 1,250 such machines in the field. In fact, that original 50-R is still drilling commercially today, company literature notes. All told, Bucyrus-Erie offers eight sizes of rotary blasthole drills, beginning with the 35-R (a 9-inch-diameter drill) and ending with the highly advanced 67-R (a crawler-mounted mammoth that drills up to 17-1/2-inch holes with a down pressure of 160,000 lb.). The 45-R, which drills holes of between 6-3/4 and 11 inches, is the company’s most popular make — more than 300 units have been sold since 1966.
Bucyrus-Erie’s drills feature rack-and-pinion pulldown for good penetration and long bit life. The operator’s cab is completely redesigned and enclosed. On its larger machines, Bucyrus-Erie has incorporated tubular plated masts that are tough and require little maintenance. The smaller machines have lattice-work masts.
Cubex Schramm
Schramm Inc. drills (marketed by Cubex Ltd.) have been on the market since 1900. Schramm is noted for being a pioneer in air flush drilling in the 1950s. The blasthole Rotadrills are designed for rapid setup, ease of operation, productivity and reliability, the company says.
Schramm blasthole rotary drills range in size from the 5-inch SC25M to the 8-5/8-inch SCH65M. The sc and sch lines are crawler-mounted. All models feature as standard equipment Cummins engines (with optional Caterpillar or Detroit diesel engines) and Caterpillar undercarriages. Modular, heavy-duty assemblies, accessories and components are engineered for long life.
Frame and mast weldments, tanks, platforms and supports are built in Schramm factories. Cubex also markets Schramm’s T685BH, a truck- mounted rig for hole sizes of up to eight inches.
Dresser Marion
Dresser Industries’ Marion Division rotary blast hole drills have been on job sites for the past 20 years. These drills can drill 9-to-15-inch holes 65 ft deep in a single pass. Dresser drills have been outfitted with an independent hydraulic propel system that provides quick response, manoeuvrability and accurate hole-spotting.
Other features include unitized construction and standard modular components for simplified erection and maintenance; common low-speed hydraulic motors; and pressurized main machinery house. Mast and drill-stem racks are made of h-beam chords and T-lacing with 100% full penetration welds. A simplified, single-reduction gear case minimizes rotating parts to reduce maintenance/repair problems on the rotary drive.
The drill control is automatic, run by electronic logic controls that set and monitor drill parameters. The hydraulics are modular and consist of independent main and auxiliary systems.
Drillex REICHdrill
Drillex’s reichdrill marketing program includes a multi-million- dollar spare parts inventory, an emergency breakdown program, and a trained technical services staff. Reichdrill’s machines range in size from the C-450-C, with a pulldown strength of 25,000 lb., to the T-750-C, a 60,000-lb. pulldown machine. The C-450-C rotary percussion drill is only eight feet, six inches wide and is powered by a Detroit 4-71T 180-hp engine. The mast is a heavy-duty, rectangular steel structure with a total length of 28 ft.
The company says its T-750-C model is the largest single-deck engine machine available. With a down pressure of 60,000 lb. and a standard twin screw air compressor producing 900 cubic feet per minute at 10 lb. per square inch, this machine is a heavyweight. Reichdrill also offers the C-750-C; at 70,000 lb. of down pressure, it is a slightly bigger machine. The unit drills up to 12-1/4-inch-diameter holes.
Gardner-Denver
Gardner-Denver likes to note on its promotional literature that its “Drillforce” rotary/percussive blasthole drills are the “most experienced blasthole drills in the world.” They could add that Gardner-Denver’s machines are well-travelled. The company’s drills are working in remote areas of such countries as Norway, Africa, Australia and Canada (in our western coalfields and eastern iron mines, for example).
The machines range in sizes from the RDC-16B, a 3-to-5-1/8-inch drill with 16,000 lb. of pulldown force, to the GD-120, which drills up to 22-inch holes from a 150,000-lb pulldown force. The GD-120 is the world’s biggest, most powerful rotary drill rig, the company says. Gardner-Denver’s bigger drills feature modular construction.
Certain models have optional electric or hydraulic rotary power, high speed or high torque. The company says innovations include electric pulldown, drill-through piperacks and automatic power tongs on the GD100.
Ingersoll-Rand
Ingersoll-Rand, an 80-year veteran of the drill business, has more than 3,000 rotary drills in service worldwide. The company says it focuses on quality manufacturing and worldwide service and parts support to maintain its share in a competitive market. It offers its own line of air compressors and down-the-hole drills.
For example, the DM45E, a 7-7/8-inch blasthole drill, features a Caterpillar tram system and Ingersoll-Rand compressors, such as the HR-2 over/under compressor. A pressure-balanced feed system provides precise bit weight control.
The DM-M Drillmaster, delivering holes of up to 10-5/8 inches, features a standard 525-hp engine for a 1,200-cu-ft-per-min compressor and 600 hp for the 1,400-cu-ft-per-min model. The rotary head is powered by a 160-hp engine. The company has also patented a system that permits angle drilling without reducing dust control efficiency.
The DM-H Drillmaster is a big blasthole machine capable of drilling 12-1/4-inch holes to 225 ft. Non-drilling time is cut significantly because the rig moves fast, climbs 30% grades and can turn on its own length.
Tamrock Driltech
The Tamrock Driltech line of blasthole drills ranges from the D25K (hole diameters between 4-3/4 and 6-3/4 inches, with 25,000 lb. of down pressure) to the R110 (9-7/8 to 17 inches with 110,000 lb.). The D25 K is crawler-mounted and can be equipped for either rotary or percussion drilling.
The D35K, D40K, D60K and D80K are all truck-mounted machines for manoeuvrability. The D80K is the largest truck-mounted production blasthole drill in the world, capable of drilling up to 12-1/4-inch holes in hard rock, a Tamrock Driltech brochure states.
The R110 features a variable-frequency a.c. electric motor for rotation. All other machines incorporate Cummins or Caterpillar engines.
For extremely hard rock conditions, Tamrock Driltech makes top-hammer blasthole drills: the 2000 (a 5-3/4-to-7-inch drill with a down pressure of 5,500 lb.) and the 4000 (an electric- powered or diesel-powered rig that drill holes up to nine inches in diameter with a down pressure of 11,000 lb.). Tamrock also features a complete series of hydraulilc, top-hammer drilling rigs called the DHA series, which can drill holes up to six inches.
And finally, Tamrock has come out with a line of drills known as the S-Series. The company says five models in this series feature new Caterpillar undercarriages, bigger and quieter cabs, a new chip-removal and dust-collection system, better serviceability and improved access to stacker valves. The S-Series runs from the smallest (a D40KS 5-to-8-inch machine) to the D75Ks (a 9-to-11-inch drill with a pulldown of 75,000 lb.).
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