THE OTHER PLAYERS

lThe Geco Mine

The Geco mine has been one of the mainstays of Noranda Inc.’s string of operating mines since 1957. This base metal “crown jewel” is a regular highlight for technical visitors from as far away as Australia and Sweden, says Douglas Sands, Geco’s supervisor of engineering services. (Sands provided the information for the bulk of this article.)

Geco employs two bulk mining methods. The first is a quarry fill blasthole in which broken ore is pulled from beneath quarried waste rock, which is introduced after the ore is blasted. The waste rock supports the stope walls. The second is open blasthole stoping. These stopes are generally the narrow stopes that are difficult to access with quarry fill raises because of depth or mining that has taken place around them. This method is employed below the 3050 level, west of the fill raise system and in 4/2 and 8/2 ore.

The quarry blasthole method was developed in the early 1960s and has been the primary production method. A surface quarry was started, and raises were driven from the top of each stoping area to surface so that waste rock could be dumped into the stopes. New raises have been put into the system as required. The last three driven to surface were bored raises. In 1986, a 1,492-ft, 8-ft-diameter raise was bored from the 1250 level to surface.

Transverse stopes are 70 ft along strike, 400 ft high and as wide as the ore width. Transverse pillars on each side of the stopes are 120 ft along strike and every third pillar, or “boundary” pillar, is 150 ft along strike. Transverse stopes and pillars are in the lower part of the ore where the thickness is greater than 30 ft. Ore that is narrower than this is generally mined with longitudinal stopes 100 ft to 150 ft along strike. Open stopes are generally longitudinal stopes ranging between 100 ft and 140 ft along strike, 200 ft high and as wide as the narrow ore width. This has proven to be the most competent dimension. Other dimensions have been used with varying success.

The transverse stope width supports a single scram with two sills, the standard pillar width supports two scrams and three sills and the boundary pillar width supports two scrams and four sills. The longitudinal stopes are generally a single scram and single sill because of the narrow width of the ore. Load-haul-dump machines are also used in these areas where the ore is narrow and a sill can be driven full width in the ore with drawpoints into the sill. Equipment and Blasting Agents Used

In drilling, Atlas Copco 3-wheel wagons are used with cop or bulroc hammers for 4 1/2-inch, down-hole drilling. Both mine air and high pressure are used. A Northwood double booster, an Atlas Copco double booster and an Atlas Copco single booster compressor are used. Mine air is nominally boosted to 250 lb per sq inch from 100 lb per sq inch at the workplace. Atlas Copco 3-wheel wagons with bbc120 longhole drills are used for 3-inch up holes, or 2 1/8-inch cable bolt holes. Some bar and arm drilling is still done with both size machines.

Mucking is accomplished by 125 hp slushers with 72-inch scrapers in 8-ft by 9-ft-scram drifts. This equipment accounts for about 70% of mine production. Some scrams have been very long, as much as 250 ft with 19 boxholes. ST-2B, JS220 Electric and ST-5 lhds are used in drawpoint drives. Most scrams and lhd drive mill holes are joined directly to the crusher via ore passes, but some tramming transfers ore from No. 1 shaft to No. 4 shaft crusher and in the lower areas of the mine where ore pass coverage is limited.

Standard mechanical bolts are installed in all development drifts as the crew is driving — 4 ft in walls, 6 ft and 8 ft in backs. A 2-ft by 2-ft pattern is used. Resin rebar bolts are used in scrams, boxholes and drawpoint drifts, 4 ft in walls and 6 ft in backs. Untensioned cable bolts 20 ft long are installed in stope walls; two 1/2-inch strands in a 2 1/8-inch h ole grouted full length with quick-setting Portland cement. A 10-ft ring spacing is used. Thirty-ft-long tensioned cable bolts are used in crown pillars and backs; three, 1/2-inch strands in a 2 1/8-inch hole, grouted at the end and tensioned to 15 tons. It is grouted full length after tensioning with quick-setting Portland. A 10-ft ring spacing is used.

ANFO in 4 1/2-inch downholes where water permits (usually not a problem) accounts for most blasting product. All holes are toe primed with water gel explosive and traced with booster cord. Non-electric caps initiate the booster cord. All non-electric caps are initiated with trunkline, while the electric caps are initiated from the surface transformer at shift change. Water gel cartridges, 1 inch by 12 inches, are pneumatically loaded into 3-inch upholes. All holes are traced with “Primacord” and initiated with non-electric caps. Either eti (formerly the explosives division of Du Pont Canada Inc.) or cil powder is used on the property in equal amounts. All blasting of longholes is done from surface after the mine is cleared of underground personnel. Drill pattern

Generally, 4 1/2-inch downholes are drilled with an 8-ft to 11-ft burden (less burden in slot areas) and 8 ft to 13 ft toe spacing. Ring drilling is incorporated in the stope drilling exclusive of slot areas. Geco tries to maintain vertical holes at the slot for void blasting, or parallel holes to the slot raise. Three-inch upholes are drilled with 4-ft to 6-ft burden on an undercut fan ring with a 5-ft to 8-ft toe spacing (though less at the slot raise).

The narrow stopes are drilled with the same equipment, but a tighter pattern is required to allow full width blasting of ore. The ore is too narrow to drill fan rings, so holes are drilled to break through at the sub-level below. The toe spacing is reduced as well. Development at the sub-levels is ore width and is 10 ft to 20 ft. Dilution

Dilution is 15% to 20%, with some from the quarry fill and some from the stope walls. The dilution is generally at the end of the stope when Geco attempts to draw maximum recovery. Even when mining between consolidated quarry fill walls, the dilution from fill is minimal. Open stope dilution tends to be 20% from the stope walls. This may be attributed somewhat to the overbreak from blasting, as well as sloughing. The narrow ore width is diluted very quickly with minor sloughing or overbreak.

In quarry fill mining, eight stopes/ pillars are being mined. The uppermost stope is mucking out at the 850 level, about 900 ft from surface. The stope height is 300 ft. The lowest stope is being mucked out at the 2850 level, approximately 2,900 ft from surface. The stope height is 400 ft.

In open blasthole mining, five stopes are being mined. The uppermost stope is being mucked out at the 650 level, about 700 ft from surface. The stope is 200 ft high and is in Main ore. Three lower stopes are mucking on the 3450 level. One 8/2 ore stope is 200 ft in height and two 4/2 ore stopes are 400 ft in height. These stopes are 3,500 ft from surface. Geco is currently mining an additional open stope at surface.

All completed stope openings have been filled with mill tailings or cemented mill tailings at a 30:1 cement- to-tailing ratio. This method has proven reliable for pillar recovery with minimal dilution and in maintaining a competent mining environment. Lockerby Mine

Vertical retreat mining (VRM) is used exclusively at Falconbridge Ltd.’s Lockerby mine, in Sudbury, Ont. Previously, the company used both Avoca and vertical bench blasting but converted entirely to VRM last year.

Both longitudinal and transverse stoping methods are used, depending on the geometry of the orebody. Tranverse stopes are generally 36 ft wide, 40-80 ft long and 170 ft high. Pillars are about the same size. In longitudinal mining situations, where the orebody is narrow, stopes are 15-36 ft wide, 100 ft long and only 70 ft high.

The nickel/copper orebody at Lockerby varies in width anywhere from 10 to 80 ft over a strike length of 300-800 ft. The ore, a weak (18,000-lb- per-sq-inch) brecciated sulphide is sandwiched between strong (28,000- lb-
per-sq-inch) granites in the footwall and weak (16,000-lb-per-sq-inch) norites in the hangingwall. The zone dips anywhere from 50 degrees to the vertical position.

Blastholes measuring 6 1/2 inches across are drilled on 10×10-ft patterns with Atlas Copco, COP6 and Ingersoll- Rand CMM and CMM2 in-the-hole drills. Boart drills are used to drill 2 1/2-inch holes for cable bolts, used for ground support. These are drilled on 18-ft spacings, 30 ft long in the hanging and footwalls. Twenty-foot cables, installed on a 7×6-ft pattern, are used to support both the over and under cuts in the VRM stopes.

For blasting, the company uses products manufactured by eti (for- merly the explosives division of Du Pont of Canada). These include Tovan Extra, Nilite, MBL 339, Tonvan El., NONELS and Anoline.

Remote-controlled mucking is used in all stopes with 5- and 2-cu-yd load- haul-dump machines (js-500 and js-220) manufactured by Eimco Jarvis Clark.

Anywhere from 6 to 10 stopes are active at any given time on levels extending to the 3,400-ft level. The shallowest active ore is on the 1,500-ft level. The Sullivan Mine

One of the oldest large-scale mining operations in Canada is the Sullivan mine at Kimberley, B.C. In continuous operation for 79 years (with the occasional labor interruption), the Sullivan mine is one of Cominco Ltd.’s three major domestic metaliferous mines. The other two are Polaris in the Northwest Territories and the Highland Valley Copper mine in British Columbia (a partnership with Lornex Mining Corp. and Highmont Mining).

Shaped like an inverted saucer and measuring about 2 km along strike and about 1.6 km wide, the Sullivan orebody has proven to be one of the resource jewels of British Columbia. Mining is concentrated in an area measuring about 1 km long and 700 m wide. The orebody dips at a shallow angle of about 10 degrees to 30 degrees .

Reserves, reported as measured and indicated, stand at 24.7 million tonnes averaging 4.6% lead, 7.1% zinc and 32 g silver per tonne (0.93 oz per ton). What percentage of those reserves are proven is kept confidential by the company. Last year, a total of 1,264,300 tonnes of ore, grading 6.0% zinc, 6.3% lead and 66 g silver per tonne (1.9 oz silver per ton), were milled. Ore came mainly from pillars left behind to support the first pass at mining. Primary mining, which accounts for only 5% of production, has begun on the fringes of the orebody, using trackless room and pillar methods.

Most production, however, comes from 15 or 20 rib pillars that measure 60 ft across and dip at an angle of about 24 degrees . Active pillars occur at depths ranging from 200 to 1,500 ft. In-the-hole drills (both CMM2 and Cubex rigs), equipped with bits 4 inches in diameter, are used for production drilling in the pillars. Upholes measuring 130 ft in length and 4 inches in diameter are drilled on 8-ft burdens. Spacing at the toe of the holes is about 14 ft.

An ammonium nitrate and fuel oil mixture (ANFO) and a slurry blasting agent both manufactured by Cominco at Kimberley, are used to charge the holes. NONEL delays and explosive bridge wires initiate the charge. Mass blasts are normally about 100,000 tons, so the Sullivan mine is still a bulk mining operation in all respects.

Partly because the original blasthole stopes were filled with either unconsolidated or weakly-cemented waste rock dilution in the pillars is very high — about 60%. There are three types of dilution, according to Mine Superintendent David McMurdo — footwall waste which has to be mined with the ore, adjacent stope fill and waste rock from the caving hanging wall. The ore has an unconfined compressive strength of about 24,000 lb per sq inch. Swellex bolts, manufactured by Atlas Copco; Split Sets, manufactured by Ingersoll-Rand; and cable bolts and shotcrete provide ground support.

Mucking equipment include 60- and 75-HP slushers and load-haul- dump machines with 5- and 8-cu-yd capacity buckets. The LHDs are of Eimco Jarvis Clark and Wagner manufacture. Ore is crushed in two stages underground and hauled to the mill by rail, which exits the underground through a portal.

About 9,000 tonnes of ore are mined each day, but 1987 production was affected by a 17-week shutdown as the result of a strike. About 2 million tonnes are to be mined in 1988. Myra Falls mine

Westmin Resources’ mining complex at Myra Falls, B.C. is in the midst of an expansion. An average of 3,327 tons of gold, silver, copper, lead, and zinc ore was milled each day in 1987 and rates should increase this year to 4,400 tons per day.

Proven and probable reserves total 12.4 million tons grading 0.07 oz gold and 1.14 oz silver per ton, 2.5% copper, 5.33% zinc and 0.38% lead.

Sublevel retreat and longhole mining are the two bulk mining methods used at both the Lynx and H-W mines, which are about a mile apart. Longhole is used in three of the five ore lenses on the properties and sublevel retreat is used in two.

The ore lenses range in width from 12 m to 130 m and strike for various lengths from 45 m to 200 m. All dip at between 40 degrees and 50 degrees .

A total of 13 stopes are active at depths which vary from 350 m to 600 m.

A Solo A 405 longhole drill, manufactured by Tamrock, is used to drill rings with a burden of 1.5 m. The distance between the toes of the holes is about 1.8 m.

AMEX and TOVEX are used as blasting agents and NONELs are used for initiation, coupled to a central blasting system.

Dilution is about 7% except in the C-390 lens, where it is about 10%.

Load-haul-dump machines, equipped with 5-cu-yd buckets are used for mucking. Remote controls are used where required. The LHDs are manufactured by Wagner Mining Equipment of Portland, Ore. The Thompson Mine

Underground bulk mining in northern Manitoba has been used for 31 years now at the Thompson mine. With a new open pit well into the removal of the surface crown pillar, the cost of producing a pound of nickel and copper in Inco Ltd.’s Manitoba Division was been reduced significantly. Underground, costs have also declined, now that vertical retreat mining (VRM) is used in almost all stopes and pillars.

The Thompson nickel/copper orebody is 2 3/4 miles along strike, averages 8-15 ft in width and is steeply- dipping at about 65 degrees -70 degrees .

Reserves are not made public by Inco, but current mining grades are about 2.85% nickel and 0.19% copper, according to George Stewart, mine engineer.

This year will see about 20 production stopes and pillars, averaging about 50-60 ft long (along strike). The active stopes are at depths ranging from 800 ft to more than a kilometre (3,600 ft). The mine has 12 in-the-hole drills — five Mission 6200 units, four Continuous Mining CD 360 units and three Mission 4150 units. The 6200 and CD 360 drills are equipped with 6 1/2-inch bits and the 4150 unit drills 4 1/2-inch holes. Drilling patterns vary from 8×9 ft for the 6 1/2-inch holes to a tighter 4×5 ft for the smaller, 4 1/2-inch holes. Blasthole lengths range from 50 to 200 ft, depending on the location of the stope in the orebody.

AMEX is used in dry holes and AQUAMEX in wet holes. Electric blasting wires and NONEL caps are used to initiate the blasts. Dilution is consistently about 20%. — 30 —