Primary Mining Method
Sub-Level Longhole retreat.
Information
1.5-m (5 ft) Split-set bolts and 4 rows of 2.7 m (9 ft) steel mats are installed on the back parallel to the development.
In case of bad brow, additional support is installed. Usually, 2.7-m (9 ft) Split-set bolts are added as well as steel mats installed perpendicularly to the ones already in place.
Primary Mining Method
Cut-and-Fill mining method.
Information
The ground support consists in 1.2-m (4ft) Split-set bolts or mechanical rockbolts with 10 cm x 10 cm (4 in x 4 in) steel plates. A 30 cm x 30 cm (12 in x 12 in) plywood is fixed under the steel plate in order to cover a larger area.
Support is systematically installed at the back and only as required on the walls.
EQUIPMENT:
Jackleg,
Gardener Denver.
Primary Mining Method
Sub-Level Longhole stoping.
Information
If the stope is larger than 11 m (35 ft): 5.2-m (17 ft) grouted rebars are added in the roe drift on a 2.4 m x 2.4 m (8 ft x 8 ft) pattern.
If the stope is larger than 15 m (50 ft): 8.2-m (27 ft) double bulged grouted cables are added in the ore drift; 2 cables per hole on a 2.4 m x 2.4 m (8 ft x 8 ft) pattern.
If a major joint is identified, the hanging wall is supported with grouted cables, but this is not a common situation.
The ground support is installed with a bolter or a scissor lift. For the installation of the rebars and cables, filling tubes and air tubes are installed in the hole and fixed with foam at the collar. The holes are then filled with cement.
Secondary Mining Method
Longhole transverse.
Information
If the stope is larger than 11 m (35 ft): 5.2-m (17 ft) grouted rebars are added in the roe drift on a 2.4 m x 2.4 m (8 ft x 8 ft) pattern.
If the stope is larger than 15 m (50 ft): 8.2-m (27 ft) double bulged grouted cables are added in the ore drift; 2 cables per hole on a 2.4 m x 2.4 m (8 ft x 8 ft) pattern.
If a major joint is identified, the hanging wall is supported with grouted cables, but this is not a common situation.
The ground support is installed with a bolter or a scissor lift. For the installation of the rebars and cables, filling tubes and air tubes are installed in the hole and fixed with foam at the collar. The holes are then filled with cement.
Primary Mining Method
Sequential grid down dip.
Information
- Scaling: Firstly, water jet machine are used to scale the stope. Afterwards, workers carry on and finish using scaling bars.
- Primary support: Steel props are installed at 1 m (3.28 ft) from the working face.
- Secondary support: As the mining progresses, steel props are replaced by timber poles that are fixed or cornered with an inflatable device commonly known as “Jackpot”. These Jackpots are placed between the pole and the roof of the stope, and inflated in order to exert pressure against the roof, approximately 22 t.
CEMENT PILLARS
In the stope, pillars made of cement blocks are erected at various places. In order to tightly press these pillars against the wall, pumped concrete is poured into a bag located in the middle of the pillar.
Attached Documents
Primary Mining Method
Overhand cut-and-fill.
Information
The ground support consists in 1.2-m (4 ft) Split-set bolts on a 1.2 m x 1.2 m (4 ft x 4 ft) pattern on the back. For every 2.4-m (8-ft) advance, a row of 4 resin anchored rockbolts, Dywidag, of 1.8 m (6 ft) long is installed. The wall support is secured by 0.9-m (3 ft) Split-set bolts. A chain link screen is installed to the back and the walls. A wooden board of 30 cm x 30 cm (12 in x12 in) with a 10 cm x 10 cm (4 in x 4 in) steel plate are used along with the Split-set bolts.
EQUIPMENT
Jackleg.
Attached Documents
Secondary Mining Method
Underhand cut-and-fill.
Information
The ground support for the underhand cut-and-fill method consists in supporting the paste fill that makes the back of the stope. After a breast has been blasted, 1.8-m (6 ft) resin anchored rockbolts, Dywidag, previously installed in the paste fill, are plated with square plywood board and 10 cm x 10 cm (4 in x 4 in) steel plates. The walls are supported with 0.9-m (3-ft) Split set bolts. A chain link is installed to the back and the walls of the stope. In the stope where screen is not required on the walls, it is installed on the floor prior to the backfilling and, therefore, is already in place for the next lift. Refer to Backfill section for more details.
EQUIPMENT
Jackleg
Attached Documents
Primary Mining Method
Mechanized Cut-and-Fill.
Information
The minimum ground support in the back consists of one bolt at each corner and one at the centre of a 1.8 m x 1.8 m (6 ft x 6 ft) pattern. If the drift is wider than 3 m (10 ft), then the centre bolt, in the 1.8 m x 1.8 m (6 ft x 6 ft) pattern, must have a length of 2.4 m (8 ft). Usually, Split-set bolts are used.
Depending on the area, steel mats of 2.7 m (9 ft) long and 3 m (10 ft) wide or expanded metal sheets are installed. If one of the walls is cut and bad ground conditions are anticipated, additional support (cemented cable bolts) is installed. The length of the cables can be as long as 18 m (60 ft).
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)
Attached Documents
Secondary Mining Method
Longhole open stoping.
Information
The ground support for sub-levels is installed during the development.
In order to prevent brow failure after a blast, cemented cables are installed. This cable bridge, as it is called, consists in two rows of cables of 6 m (20 ft) long. The cables are installed with a 1.5-m (5 ft) spacing.
Primary Mining Method
Sub-level long-hole retreat with backfill.
Information
6-m (20 ft) cables are installed on the hanging wall from the sub-levels.
Cable bolt holes are drilled by the Solo rig and the cables are installed by the service crew.
Primary Mining Method
Longwall.
Information
Refer to the standard plan attached.
Example of a prestressed elongate prop.
Attached Documents
Primary Mining Method
Open stope.
Information
When dykes are encountered, pillars are left to give support to the walls. No need for more ground support, since the quality of the walls is exceptional. Dilution problems occur occasionally and are related to geological structures.
Primary Mining Method
Retreating Longhole.
Information
Cables are installed in order to protect the access drift. When the stope is longer than 30 m (98 ft) and that backfilling is impossible, cables are installed on the hanging wall. In areas of shallow vein, the stope opening cannot be completely backfilled. For this reason, pillars are left every 30 m or 35 m (98 ft to 115 ft).
Primary Mining Method
Long-hole.
Information
Anchor cables were installed in the hanging wall from the sub-levels in three of the four stopes, so far. The cables are 6-m (20 ft) long, one cable every 1.5 m (5 ft). No difference was observed between these stopes and the one where no ground support was used.
EQUIPMENT
Long-hole drill Atlas Copco H104 (holes of 64 mm [2,5 po]).
Secondary Mining Method
Room-and-Pillar.
Information
1.5-m (5 ft) friction galvanized Split-set bolts of 33 mm (1.3 in) diameter.
EQUIPMENT
Jackleg.
Primary Mining Method
Long hole open stope.
Information
Cemented cables are used occasionally. To eliminate the support brought by the cables in the blasting areas, the cables are covered with plastic tubing.
Primary Mining Method
Long-hole sublevel retreat.
Information
The drifts will be supported with Split-set friction bolts of 2.1 m (7 ft) with a spacing of 1.2 m to 1.5 m (4 ft to 5 ft). Anchor cables of 6 m (20 ft) will be installed, 3 cables per row spaced every 2 m (7 ft).
Attached Documents
Primary Mining Method
Longhole modified Avoca.
Information
Corrosion of ground support elements caused by the presence of ground water is a great concern. Consequently, it has been estimated that Split-set bolts have a working life of 12 months. Full column grouted Gewi bars have a working life in excess of 24 months and are suitable for use in the 1A zone where production is completed within 24 months of development.
The minimum support consists in wiremesh and galvanised Split-set friction bolts of 2.4 m (8 ft) at the back and walls. When there is presence of ultramafic rock of 2 m to 3 m (6.6 ft to 10 ft) thick, cemented cables are installed and the bolts are cemented. All stoping areas to be drilled with upholes are sprayed with a fibrecete (backs, shoulders and ultramafic material on footwall) and cable bolted.
Primary Mining Method
Modified Avoca.
Information
The wall stability is secured by the backfill, stope dimensions and cable bolts installation. The maximum hydraulic radius for this material is 6.5 m (21 ft), which is equivalent to a 28-m (92 ft) stope length. The planned length per stope of 25 m (82 ft) should secure their stability. Single bulbed cable strand are used.
The cable bolt density for each block will be determined from geotechnical mapping of the associated development. Previous experience with similar orebodies indicate this will be in the range of 0.25 to 0.35 cable/square meter. Plating and tensioning of the cables shall be completed within one week of installation and not less than 24 hours after the installation. The plating will provide additional surface restraint to any unstable wedges that may loosen during long-hole production.
Attached Documents
Primary Mining Method
Mechanized cut-and-fill stoping.
Information
The ground support pattern consist of 2.4-m (8 ft) galvanized Split-set friction bolts. The bolts are installed on a same row with a 0.9-m (3 ft) spacing which helps to fix the metal straps. Each row is spaced at 1.5 m (5 ft).
When the stope width is exceeding 4 m (13 ft), the length of bolts is increased to 3 m (10 ft) by maintaining the bolt spacing. When the stope width is exceeding 6 m (20 ft), a geotechnical study is required.
EQUIPMENT
Single boom Jumbo for scaling and ground support installation.
Attached Documents