Between a Rock and a Hard Place

As you read this story there is probably not a single idle exploration rig in the country. Flow-through financing and some excellent exploration results have made sure of that. But the uncertain future of flow-through means some contractors are thinking twice about buying new rigs, which, in some cases, can cost up to $250,000 fully equipped. Finding people to operate the rigs is probably an even bigger problem for today’s contractor.

In 1986 Craelius, a Swedish diamond drill manufacturer, celebrated 100 years in the business. The company was started by Per Anton Craelius and G. A. Granholm. In Canada the company’s drills, suited mainly for underground exploration work, are distributed by Unicorn Abrasives of Canada (Brockville, Ont.). In 1986 Craelius introduced into the Canadian market a new, small, compact diamond drill called the Diamec 230. Currently on an exhibition tour across the country, this one-man, skid- mounted hydraulic drill replaces the small, screw-fed machines. One man can drill BQ-size holes to a maximum depth of 1,000 ft and the rig can drill AQ-size holes up to 500 ft deep.

This year Craelius plans to bring to Canada another new machine — a big, hydraulic diamond drill — for drilling 5,000-ft, BQ-size holes from surface. A prototype of the drill, tentatively called the D4, is undergoing testing in France, says Eric Wickman, manager of Craelius’ Canadian division. A Quebec contract drilling company has expressed interest in the machine.

At Longyear Canada (North Bay, Ont.), marketing manager Bud Frair says his company has had no problem meeting the demands of the diamond drill contractors during the busy winter drilling period. Sales are good, he says, but not any heavier than usual.

In September, 1986, Longyear introduced its new line of wireline drill rods which are hardened by an induction heating process. Frair expects that once the flow-through activity settles down in the spring, contractors will report back to them on the performance of the new rods. They are expected to have twice the abrasion resistance of conventional, chrome- plated rods.

Business has been brisk at Toronto- based jks Boyles International. “In terms of sales we are having our best year since 1979,” says market manager William Baynton.

The BBS-75 drill, introduced this year, is rated for depths of 1,770 m for single-line units to 3,540 m for the double-line model. Both represent the deepest capacity available in this class of drill, the company says. “A new, heavy-duty, welded front end and hoist (with a capacity to lift 50,000 lb) provide the strength and durability needed for deep holes,” jks’s Gary Pidher says. Spindle speeds range from 66 to 1,100 rpms and a standard diesel engine is rated at 125 kW.

The company’s JKS-300 Super Drill has become a favorite with exploration companies and drill contractors, Pidher says. The modular hydraulic system can be diagnosed and serviced with ease.

For underground applications, jks has introduced a 92-kW electro- hydraulic unit that can drill holes up to 1,400 m deep. Called the 46 ugeh, it is also manufactured in modules for ease of transportation and maintenance. The unit can drill holes in any direction. The power unit is 2.05 m long and 1.42 m high while the drill unit is 1.89 m long and 1.75 m high.

An old way of drilling bedrock may make a comeback of sorts in the gold exploration camps of northwestern Quebec. Using a 6-in, Ingersoll Rand in-the-hole hammer and a tungsten carbide button bit on a dk 40 Drilltec rotary-percussion rig, Foratek International (Dorval, Que.) plans to put down a number of holes totalling 1,000 ft through solid bedrock on a gold property northeast of Amos. Like the reverse-circulation method used for drilling in glacial overburden, this method could prove an inexpensive way of getting a large-diameter sample (up to 10 in) of bedrock suitable for assays of previously discovered gold zones. It could become a relatively inexpensive way to take small bulk samples. Cuttings are 1/4 in or smaller and drilling rates are 20 ft-35 ft per hour at a cost of about $16 per ft. Foratek plans to drill holes 115 ft-50 ft deep to intersect a gold-bearing zone. But diamond drillers need not fret. Drill core will always be needed to map geological structure and lithology — information which leads geologists to the major discoveries. Drilling Overburden

One drilling method that has become an industry standard for locating gold deposits under overburden has been perfected by Overburden Drilling Management. Last year odm expanded its exploration drilling activities by opening a commercial heavy minerals concentrating lab in Rouyn, Que., in the heart of the Abitibi greenstone belt. The expansion doubles the company’s capacity to analyse samples of glacial overburden in this major gold exploration area of northern Quebec.

Odm, founded in 1971 by former Ontario Geological Survey geologist Stuart Averill to provide expertise in using glacial overburden as an exploration tool, has grown steadly over the years. Today the company has 30 employees and accounts for about half of the total Canadian deep overburden experience, general manager Nancy Averill says.

The technology for drilling in overburden (two methods are used: reverse circulation and sonic drilling) and the heavy metals classification techniques developed by odm have become industry standards in gold exploration from coast to coast. The methods are based on the principle that soils derived from subcropping bedrock mineralization was incorporated into the ice of overriding glaciers that covered most of the country as recently as 15,000 years ago and was later deposited as a mineralized dispersion train in the “down ice” direction from the source.

By screening 8-kg samples of glacial overburden to 10 mesh and preconcentrating it on a shaking table, odm can remove almost all gold and other heavy minerals from the sample. Then, by examining these mineral grains under a microscope, odm geologists pick out significant dispersion trains (those samples with more than 10 gold particles) and estimate how far the gold grains have been transported by the glaciers (100 m or less for delicate grains and up to one km for abraded grains).

Odm has successfully identified gold dispersion trains associated with several significant gold deposits in northern Saskatchewan, on the McCool property in Ontario and on the Golden Pond properties in Quebec. Every new overburden hole drilled in these areas adds to odm’s knowledge of the Quaternary stratigraphy of these gold belts, which could lead to further gold discoveries. Reverse Circulation (Tricone)

Almost all of the reverse circulation drills now used by contractors in eastern Canada are the mp Mark iv — an all-hydraulic, rotary drill manufactured by Acker Drill (Scranton, Penn.), says Jules LaRocque of LaRocque Drilling Supplies (Laval, Que.). LaRocque imports, modifies and distributes the drills to Canadian contractors. In western Canada Acker drills are distributed by Canada Wide Diamond Drilling in Vancouver. Originally designed as an auger drill, the Acker unit has an 11-ft stroke compared to only 24 in on other units. A high torque capacity of 5,036 ft-lb is another feature that adds to the popularity of this drill, LaRocque says. The drill, powered by a 73-hp diesel engine, can be mounted on a trailer, truck or crawler unit. With crawler pads 12 in wide, ground pressures are 4.7 lb per sq in, which permits access in wet, boggy terrains. Although the unit has a hefty price tag, LaRocque says some contractors are ordering additional rigs.

It wasn’t a mineral exploration project that was, perhaps, the largest, single, reverse circulation drilling project in the country (some 150,000 ft). Rather, it was an engineering project, carried out by Pitts Engineering Construction of Edmonton, Alta., last year along a 2.3-km section of the cp Rail grade reduction project in the Rogers Pass of British Columbia. Using the Atlas Copco Odex system on six crawler-mounted drills, 40-ft holes, 5 1/2 inches in diameter, were drilled throu
gh overburden at about 60degrees inclination to solid rock. Then 5 1/2 -in casing, in 10-ft lengths, was installed in each hole followed by steel rock bolts to support the rock and soil slopes. Casings were filled with grout, placed at 150-lb-per-sq in pressure, as they were withdrawn.

“The Odex system worked quite well in the difficult ground,” says Peter Bradley, project engineer for Pitts Engineering. “And there was a general tendency to underestimate consumables on this project.” Sonic Drilling

Borros, a drill manufacturer based in Sweden, has developed a very compact, light, rotary, percussion drill rated at 24 kW. Measuring just three m long and about two m high, this crawler-mounted drill, weighing just 1.6 tonnes, is very mobile and can poke holes through glacial overburden to take relatively undisturbed samples from up to 100 m below the surface. Powered by either a gas or diesel engine it can deliver up to 1,100 blows per minute at 160 J per blow. The unit is called the Polhydrill.

John Archibald, vice-president of operations for Sonic Soil Sample and operations manager for Toronto-based Borros Canada, says there are two Polhydrills in Canada. Their first machine has drilled in the order of 2,000 ft-3,000 ft for Sherritt Gordon, Echo Bay Mines, Pamour Inc. and the Ontario Geological Survey, among others, in all types of overburden including glacial tills and unconsolidated soils, silts and clays.

Relatively undisturbed samples up to two m long and anywhere from 2 1/2 -6 inches in diameter can be extracted continuously using the wireline principle up through the centre of the dual tube system. “We’ve been using a hollowed-out, tungsten carbide cross bit with good success,” Archibald says. Costs so far have ranged from $5 to $8 per foot.

Another drill that has proven itself in the field is the Wink Vibra-Corer Drill, marketed by Sonic Soil Sampling. Developed by Fred Wink, this light, compact unit operates on the principle of drill string oscillation. Drilling in glacial overburden in the Matheson area of northeastern Ontario averaged 6.4 ft per hour in holes averaging 45 ft deep, Archibald says.

Schramm Inc. of West Chester, Penn., manufacturers five much larger rotary, hydraulic drill rigs suitable for sonic overburden exploration drilling. Their power ratings range from 208 kW to 372.5 kW. They are marketed in Canada by Cubex in Winnipeg, Man.