Primary Mining Method
Sub-Level Longhole retreat.
Information
DRILLING PATTERN
Toe spacing: less than 2.4 m (8 ft).
Burden: 1.8 m (6 ft).
Hole diameter: 63 mm and 76 mm (2.5 in and 3 in).
If the stope is narrow, at least 4 holes are drilled on a section. The sections are drilled vertically upward.
DRILLING SEQUENCE
Ideally, if the stope is small, it is entirely drilled before blasting. Where many headings are available, it gives the flexibility to drill and blast by section. 4 sections have to be drilled in advance, and a minimum of 2 sections is required.
Planning: Hand drawn.
Dilution control: Generally, there is no dilution. Sometimes, part of dilution is included in the design due to the irregularities of the ore body.
DRILLING EQUIPMENT
Cubex drill (diesel hydraulic) and Boart BCI2 drill.
Primary Mining Method
Cut-and-Fill mining method.
Information
DRILLING PATTERN
Height: 2.7 m (9 ft).
Length: 1.8 m to 3 m (6 ft to 10 ft) breasts.
Under certain conditions, the top sill pillar is under high pressure and seismic activity occurs. In order to relieve the stress in the pillar, destress blast is performed. The technique is to drill a lift with 2.4-m (8 ft) upper holes with longer holes of 4.6 m to 9.1 m (15 ft to 30 ft) on a 1.2 m x 1.2 m (4 ft x 4 ft) pattern.
EQUIPMENT
Jackleg
Primary Mining Method
Sub-Level Longhole stoping.
Information
The drop raise has to be drilled first in order to create the initial cut for the stope. The initial cut is usually located 1.2 m (4 ft) from the last blasted section. This way, the cemented rockfill is not damaged during the blast. When this is completed, the drilling continues with the following specifications:
- Hole diameter: 92 mm (3 5/8 in).
- Burden: 2.4 m (8 ft).
- Spacing: 2.4 m (8 ft).
- Drilling productivity: 107 m/shift (350 ft/shift).
- Estimated drilling cost: $13.12/m ($4/ft).
In narrow area, 1.2-m (4 ft) trench pattern has been tried. Now, the pattern is used a dice five pattern.
EQUIPMENT
- Simba drill is tested. Expected production: 183 m to 213 m per shift (600 ft to 700 ft per shift).
- Cubex drill
- Retrac drill bit from Sandvik for a good drilling accuracy.
Retrac drill bit: The new Spool-Shape Design (SSD) provides for a frontal and rear support that keeps the bit lined up in the hole and makes the hole straight.
Secondary Mining Method
Longhole transverse.
Information
The drop raise has to be drilled first in order to create the initial cut for the stope. The initial cut is usually located 1.2 m (4 ft) from the last blasted section. This way, the cemented rockfill is not damaged during the blast. When this is completed, the drilling continues with the following specifications:
- Hole diameter: 92 mm (3 5/8 in).
- Burden: 2.4 m (8 ft).
- Spacing: 2.4 m (8 ft).
- Drilling productivity: 107 m/shift (350 ft/shift).
- Estimated drilling cost: $13.12/m ($4/ft).
In narrow area, 1.2-m (4 ft) trench pattern has been tried. Now, the pattern is used a dice five pattern.
EQUIPMENT
- Simba drill is tested. Expected production: 183 m to 213 m per shift (600 ft to 700 ft per shift).
- Cubex drill.
- Retrac drill bit from Sandvik for a good drilling accuracy.
Retrac drill bit: The new Spool-Shape Design (SSD) provides for a frontal and rear support that keeps the bit lined up in the hole and makes the hole straight.
Attached Documents
Primary Mining Method
Sequential grid down dip.
Information
In stopes, drilling is performed with hydraulic drill or hydropower drill rig.
Attached Documents
Primary Mining Method
Long-hole bench stoping with backfill.
Information
Historically, drilling has been achieved uphole, but it is planned to drill downhole in the future.
- Hole diameter: 64 mm (2.5 in).
- Burden: 400 mm to 500 mm (15.75 in to 20 in).
- Spacing: 400 mm to 500 mm (15.75 in to 20 in).
- Arrangement of the hole: varies from dice five to zigzag and in line depending on the stope.
EQUIPMENT
Atlas Copco Simba H104.
Primary Mining Method
Overhand cut-and-fill.
Information
The drilling is achieved by breasting. The breast size is usually 3 m (10 ft) high, 2.4 m to 3 m (8 to 10 ft) long and the width varies according to the vein. The minimum width is 1.8 m (6 ft) in the Lucky Friday zone and 2.1 m (7 ft) in the Gold Hunter zone. The minimum width is regulated by the size of the equipment.
EQUIPEMENT
Jumbo and jackleg.
Attached Documents
Secondary Mining Method
Underhand cut-and-fill.
Information
The drilling is done by breasting with the void being at the back instead of the floor. The breast is usually 3 m (10 ft) high, 2.4 m (8 ft) to 3 m (10 ft) long and excavated at the width of the vein. The minimum width for the Lucky Friday vein is 1.8 m (6 ft), and 2.1 m (7 ft) for the Gold Hunter vein. The minimum width is ruled by the equipment size.
The maximum spacing between holes is 61 cm (24 in). The first two rows are drilled with an ascending angle in order to allow the rock to come out. No cut is used in the drilling pattern. Instead, 0.3 m (1 ft) of waste rock is left under the backfill. This creates enough void for the blast.
EQUIPMENT
Jumbo and jackleg.
Primary Mining Method
Mechanized Cut-and-Fill.
Information
Generally, the drilling is achieved breasts of 3.6-m (12 ft) high and 3-m (10 ft) long. The width of the drilling pattern varies according to the ore width. If the stope is accessible in the centre or at an extremity, one or two faces are available.
EQUIPMENT
- Tamrock-Secoma electric-hydraulic single boom Jumbo. The boom is not paramatic (parallel holding), but it does not seem to reduce productivity.
- Tamrock-Secoma electric-hydraulic bolter.
- Elphinstone 3.5-yard Load-Haul-Dump (air-conditioned cabin).
Secondary Mining Method
Longhole open stoping.
Information
UPHOLE DRILLING
- Hole diameter: 64 mm (2.5 in).
- Burden: 1.2 m (4 ft).
- Spacing: 1.5 m (5ft).
DOWNHOLE DRILLING
- Hole diameter: 102 mm to 152 mm (4 to 6 in).
- Burden: 1.5 m (5 ft).
- Spacing: 1.5 m (5 ft).
Only 5% of the stopes are drilled with downholes. The holes are planned 60 cm to 90 cm (2 ft to 3 ft) inside the ore limit. In order to verify the drilling precision, 10% of the holes are planned to break through in the upper level. The other holes are 60 cm (2 ft) shorter.
EQUIPMENT
- Boart Stope master
- Boart BCI-21
Secoma long-hole drill. The Secoma is preferred because it is easy to move from one stope to another.
Primary Mining Method
Sub-level long-hole retreat with backfill.
Information
Depending on the width of the vein, 4 patterns may be used:
- alternative pattern;
- "dice five";
- staggered;
- in rows.
The burden and the spacing depend on the width of the vein. The minimum drilled width is 1.3 m (4 ft). It results in a broken stope size of 1.5 m (5 ft). When the vein is narrow, the base is opened at least 2 m (7 ft) to ensure the flow of the ore.
The drilling diameter is 76 mm (3 in) and the sections are drilled at 70 degrees. This practice, according to them, assures better breakings but increases the risks of borehole deviations. The bonus is paid according to the drilling accuracy.
EQUIPMENT
- Longhole drill: Tamrock Solo 1020 with a carousel with a maximum capacity of 50 m (164 ft) of steels.
- The purchase of a smaller drill is budgeted in order to reduce the drilling diameter for the narrow stopes as well as the required space for the raise drilling.
- Guide rods are used to ensure the drilling accuracy.
Attached Documents
Primary Mining Method
Longwall.
Information
Drilling is achieved using pneumatic hand-held machine. However, a new technology programme is aimed at developing and introducing new technologies to improve safety, health and productivity, and to provide the company with a sustainable competitive advantage based on continuous improvement in specific areas of focus. The strategy has two thrusts:
In the short term, drilling will be improved by using either pneumatic or hydro-powered hand-held machines or drill rigs and, where geology allows, using trackless equipment. Blasting will be by means of explosives with conventional initiation systems.
In the long term, drilling will be improved by continuously mining by means of mechanized cutting, in conjunction with non-explosive rock-breaking techniques.
The advantages are:
- Removing people from high-risk areas;
- Developing the work environment in line with global trends and changing from the current arduous, labour-intensive work to a more skilled work profile that is less labour intensive;
- Improving productivity;
- Reducing unit costs.
Attached Documents
Primary Mining Method
Open stope.
Information
When Normandy acquired this operation, the hole diameter was 57 mm (2.25 in) and the dice five pattern (2-1) was used with burden and spacing of 1 m (3.3 ft). To increase precision of the drilling, the new operators increased the drilling diameter to 64 mm (2.5 in). The average length of the holes is 13 m (43 ft). The drilling pattern was also changed to two staggered holes, with a burden of 600 mm (24 in) and a spacing of 1 m (3.3 ft).
This pattern is used 90% of the time. When the vein is larger than 1 m (3.3 ft) or for the first drilling sections near open raises, two holes aligned on a same section are drilled. The burden then increased to 900 m (2953 ft) and the spacing increased up to the vein width.
EQUIPMENT
Longhole drill Quasar.
Steels of 1.8 m (6 ft).
Attached Documents
Primary Mining Method
Retreating Longhole.
Information
The drilling is mainly done upward from the lower drift.
A 64-mm (2.5 in) diameter was previously used. In order to increase the drilling accuracy, the diameter has been increased to 76 mm (3 in).
Drilling pattern: Dice 5.
Burden: 2 m (6.6 ft).
Spacing: 1.5 m (5 ft).
The minimum blasted width is 1.8 m (6 ft). Holes are drilled at a minimum distance of 0.5 m (1.6 ft) from the contacts. Sections are drilled vertically, unless there is no opening at the upper level.
EQUIPMENT
- Tamrock 1006 RA and Solo 620 drills.
- Steels T-45.
- Speed rods (precision of 1.2%).
- Guide rods (precision of 0.76%).
Guide rods obtain better precision results but frequently break and are expensive (approximately 800 Australian dollars per rod).
Actually, steels of 1.8 m (6 ft) with 2.4-m (8 ft) guides and Retract bits are used.
Primary Mining Method
Long-hole.
Information
Downhole drilling is preferred in order to obtain a better control of the deviation.
Hole diameter: 64 mm (2.5 in).
The first long-hole stope was blasted following a drilling pattern of 1.5 m x 1.5 m (5 ft x 5 ft) with upper holes. The blasting was done with 6 or 7 rows at a time. Some problems occurred by the formation of a bench within the stope. The dip was 35 degrees.
The drilling pattern was adjusted to 1.2 m x 1.2 m (4 ft x 4 ft) for the second stope. First, an opening 8 m to 9 m long (26-30 ft) was taken and the two rows were subsequently blasted at a once.
EQUIPMENT
- Atlas Copco drill H104.
- Boart Balistic bits.
- 1.8-m long (6 ft) steel rods.
- 2 guide rods are used.
Secondary Mining Method
Room-and-Pillar.
Information
The drilling is done manually with a jackleg.
EQUIPMENT
- Jackleg
- Balistic bits, "knock-on bit" type.
Primary Mining Method
Long hole open stope.
Information
The drilling is done with upholes.
Diameter of holes: 64 mm (2.5 in). Burden of 1.8 m (6 ft) if there is an upper level.
Burden of 1.6 m (5.25 ft) if there is no upper opening (blind drilling). The burden is reduced to ensure a good cutting since the sections are not inclined for a good precision drilling.
Spacing: 1.5 m (4.9 ft). The drilling is generally done 6 months in advance.
EQUIPMENT
Atlas Copco drill 104/157.
Primary Mining Method
Long-hole sublevel retreat.
Information
According to the diameter of the drill holes, the drilling patterns are as follows:
- Hole diameter of 89 mm (3.5 in): Burden of 2.0 m (5.5 ft) and spacing of 2.5 m (8.2 ft).
- Hole diameter of 76 mm (3 in): Burden of 1.8 m (6 ft) and spacing of 2.25 m (7.4ft). Commonly used.
- Hole diameter of 64 mm (2.5 in): Burden of 1.5 m (5 ft) and spacing of 1.5 m (5 ft).
- The drilling is done 2 or 3 rows in advance and blasted immediately.
Performance: approximately 120 m (394 ft) for a 10-hour shift.
EQUIPMENT
Tamrock longhole drill 1008 with carousel. Steel rods of 1.8 m (6 ft). Equipment requires a height of 4.2 m (13.7 pi) to operate.
Primary Mining Method
Longhole modified Avoca.
Information
The planning of drilling sections varies depending on the width of the mineralized zone. For operational reasons, the minimum width is fixed at 2 m (6.6 ft).
DRILLING PATTERN
- Burden: 2 m (6.6 ft).
- Spacing: 1 m to 1.8 m (3.3 ft to 6 ft).
- Drilling diameter: 76 mm (3 in).
- Inclination of ring: 90 to 60 degrees (recommended 80 degrees).
Generally, two holes are drilled on a same section along each walls. A third hole is drilled between drilling sections according to a dice five pattern.
The majority of drilling is performed by down holes to minimize personnel exposure to the brow. Where upholes are required to be drilled, additional support (shotcrete and cable bolts) is installed in the drive backs.
EQUIPMENT
The drilling equipment for the 1A zone was not yet purchased. However, the following equipment is considered:
- Tamrock Mercury 1LC10
- Tamrock Mercury 1LC22 (preferred option)
- Tamrock Solo 720 ZRF
- Atlas Copco Simba H254
The required parameters for the selection of a drill for 1A zone are the following:
- Leasing 3 to 6 months (with option to buy).
- Narrow vein drilling, 2 m to 2.5 m (6.6 ft - 8 ft).
- Drift dimensions of 4 m x 4.5 m (13 ft x 14.7 ft).
- Drill holes of 20 m (66 ft) long upward or downward.
- Drilling diameter of 76 mm (3 in).
- Electric/hydraulic drill.
- Required productivity of 2500 m (8202 ft) monthly.
Attached Documents
Primary Mining Method
Modified Avoca.
Information
The drilling is done from the upper drift. This downhole drilling provides a safer environment and allows parallel holes to be drilled.
On a typical stope width of 2.1 m (7 ft), the blast holes are 64-mm (2.5 in) in diameter, drilled on a "dice five" pattern. This will consist of a hanging wall and footwall hole on each row followed by a third hole located in the middle of the vein and drilled between each row.
The footwall hole is drilled 0.2 m (8 in) into the basalt to ensure complete extraction of the high grade massive ore that tends to sit on the footwall contact.To prevent unplanned dilution, the hanging wall hole will not be drilled closer than 0.6 m (24 in) from the contact. The burden is 1.5 m (5 ft) and the spacing is 1.6 m to 1.9 m (5.2 ft to 6.2 ft) depending upon the width of ore. The first mined stope with parameters mentioned above will be under close monitoring. This will allow the adjustment of the pattern and even eliminate the centre hole for stopes with widths less than 1.6 m (5.2 ft).
EQUIPMENT
It is planned to use either an Atlas Copco Simba H-157 or a Tamrock Quasar NV.
Attached Documents
Primary Mining Method
Mechanized cut-and-fill stoping.
Information
The stopes are designed to allow for profiling of the hanging wall to a minimum angle of 65 degrees. Usually, a dilution is assumed on the footwall to provide adequate clearance for the equipment. The minimum width is 3.3 m (11 ft).
A lift is 4.3-m (14 pi) high, corresponding to 1-m (3.3 ft) brow (free face) and 3.3 m (11 ft) of rock to break. Since there is a brow, no burn cut is required. The drilling pattern consists of 4 rows of holes, plus floor holes. The burden between holes is approximately 800 mm (31.5 po). The advance is done by rounds of 2.8 m (9.2 ft). Additionally, 2 lifters and a knee hole are drilled in the footwall to maintain the minimum mining width creating a ledge in the basalt footwall. Where the ore is wider, it is critical that the footwall holes are drilled on the basalt contact to ensure complete extraction of the high grade massive ore that sits on the footwall contact. Likewise, to prevent unplanned dilution, the hanging wall holes will not be drilled closer to 0.5 m (1.64 ft) from the contact.
Grade pins are surveyed on the walls and from these grades, lines are extended to the face to guide the jumbo operator whilst drilling.
Two cimented pillars are left for the mining. When the mining approaches cemented pillars, only 4 lifts are taken, leaving a 3.3 m (11 ft) crown pillar of ore. The pillar is recovered by upper holes, drilled by the jumbo retreating to the access.
EQUIPMENT
- Single boom Jumbo
- Bit of 45 mm (1.75 in) in diameter.
Attached Documents