INNOVATIONS Revolutionary Reamer

Most mine engineers have heard, one way or another, about the development in Quebec of a new way to drive raises in underground mines. Tests have shown the method is faster and less expensive than conventional reaming and safer than the conventional, manual Alimak method. The new technique involves the use of a new reaming machine called the Roger Drill — named after inventor Roger Masse. The first generation prototype of the machine had been tested at Noranda’s Chadbourne mine in 1983, the El Coco mine in 1984, Muscocho Explorations’ Montauban mine in 1983 and 1986, and at Lac Minerals’ Bousquet mine this summer. The prototype consists of a reaming head fitted with three conventional, pneumantic in-the-hole hammers (manufactured by Mission Drilling Products of Houston, Tex., and distributed in Canada by Cubex Ltd. of Winnipeg, Man.) and equipped with conventional 8-inch-diameter button-bits (also manufactured by Mission). It was used to drive relatively short raises (100-300 ft long) ranging from 42 to 52 inches in diameter. Only two were driven at angles of less than 90 degrees and the longest was 300 ft long. The machine is now at the Belmoral mine in Val d’Or, Que.

Results have been so successful that a commercial model of the patented drill should be available for purchase by mining companies by February, 1988, says Louis Marcoux, an engineer for the Quebec Centre for Mineral Research (qcmr) in Ste-Foy, Que. The model is capable of driving circular raises ranging from one to five ft in diameter, suitable for ore and waste passes, ventilation raises and slot raises in stopes. The qcmr helped fund the 4-year research-and-development project. The manufacturer of the reaming heads will be Machines Roger International of Val d’Or.

An even larger-diameter, horizontal model of this revolutionary drill is in the planning stages. Such a scaled-up machine, it is hoped, would be used to drive horizontal or slightly inclined tunnels in much the same manner as the heavier, more expensive full-face tunnel boring machines, which are used worldwide. These machines are put to work mostly on civil engineering projects such as long highway tunnels, hydroelectric projects and railway tunnels.

So far, though, the Roger Drill has excavated relatively short, circular raises measuring only 2-5 ft in diameter and inclined at angles only as flat as 63 degrees from the horizontal. Much work is yet required to perfect a machine that can drill horizontal tunnels. However, what makes the Roger Drill unique is the way it excavates the opening, Marcoux says. 2000

Instead of bringing the cutting part of a drill tool into contact with the full face of the excavation, the drill cuts just two concentric circles in the rock. As the head of the reamer rotates, the ith hammers cut two circular rings, eight inches wide, in the rock. The ridge of un-drilled rock between the circular cuts simply breaks off as energy from the drill is transmitted indirectly through the rock while the machine advances. The result is a full- face opening. Broken rock falls into the the opening below. This method of rock removal results in larger chunks of rock — making it easier than fine cuttings to muck out at the bottom of the raise.

Since the amount of rock actually drilled by the button bits is relatively small, compared to full-face machines, bit costs are greatly reduced, Marcoux says. The cost of reaming bits on conventional raise boring machines often represents more than half of the over- all cost of driving the raise.

By mounting each hammer on the reaming head in such a way as to allow complete freedom to turn in its sprocket, the Roger Drill ensures uniform wear on the bits.

At the Montauban mine in 1986, a 42-inch-diameter raise was drilled in a biotite, garnet gnieiss with a high silica content and a uniaxial compressive strength ranging from 7,000 lb to 27,000 lb per sq inch. Carbide button bits were used. Penetration rates were excellent at 72-84 inches per hour, with peaks of 100 inches per hour.

“We estimate that, with recent improvements, the reamer will be able to drill a 5-ft diameter hole about 40 ft in one work shift,” Marcoux says. For short raises, one shift is normally required to drill the pilot hole necessary to hold the drill string from which the reamer is suspended.

The pull force required to drill a large-diameter raise is greatly reduced as well with the new drill. Only 6,000 lb of force are required.