Description of mining methods (step by step)

Apollo Gold Corporation - Diamond Hill mine (U.S.A)

Primary Mining Method

Sub-Level Longhole retreat.
Information

DEVELOPMENT SEQUENCE
The Diamond hill ore bodies and mine workings are in exceptionally solid unfractured rock and accordingly are amenable to low cost sublevel open stoping methods. Ore is transported to the Montana Tunnels mill facility by truck. There it is processed in a separate circuit designed for Diamond Hill ore. Most gold is recovered into a high grade pyrite concentrate and sold to Japanese smelters.

  1. An access is developed from the main ramp up to the stope. The ore is drifted out longitudinally from one limit to the other. The vertical interval between the ore drifts is 20 m (65 ft).
  2. A raise is driven at the extremity of the block to create the first cut.
  3. In order to precise the geological interpretation, long-holes are drilled upwards at specific locations indicated by the geologist. These holes are drilled with the production drill. The mud is then sampled in order to determine the ore limit.
  4. Once the ore limit has been determined, drilling section plans are generated and production drilling is done. The drilling is achieved upward.
  5. The breaking of the rock generally starts only when the entire block has been drilled. If there is more than one stope available for drilling, the blasting can start earlier using the flexibility created by the heading available.
  6. The mucking is achieved longitudinally. When the brow of the stope is open, the mucking is done remotely. The mining sequence progresses from top to bottom and the stopes are not backfilled.
Attached Documents

Coeur Silver Valley Inc. - Galena Mine (U.S.A)

Primary Mining Method

Cut-and-Fill mining method.
Information
  1. Development in the ore of the upper and lower drift. The distance between the levels is 91 m (300 ft).
  2. Development of the service raise.
  3. Excavation of the stope. Two options: the first option consists in starting the stope from the level. The second option is to develop a sub-drift of 6 m (20 ft) higher than the lower drift. In the first option, 3 lifts are taken to a maximum opening height of 7.3 m (24 ft). The drift is timbered and the chute is built. Once the timber is completed, burlap is installed over the cribbing to backfill the stope. The stope is backfilled to a height of 0.9 m (3 ft) from the back. In the second option, a sub-drift is driven 2.7 m (9 ft) high and the cut-and-fill sequence starts.
  4. The stope is excavated by breasting. If ground seismic activity occurs, a destress blast is performed.
  5. When the sill pillar is 6.4 m to 7.3 m (21 ft to 24 ft) high, its entire height is breasted with 1.8-m (6 ft) advance according to the following sequence.

SILL PILLAR RECOVERY

  1. Blast a 1.8-m (6 ft) advance breast to the total height of the pillar.
  2. As the muck is being pulled out, 25 cm x 25 cm (10 in x 10 in) timber is installed to support the walls and the level track. The timber is installed on an 2.4 m x 2.4 m (8 ft x 8 ft) spacing pattern.
  3. When the stope is completely excavated, it is backfilled and the top drift is accessible.
Attached Documents

Echo Bay Minerals Co.- K-2 Mine (U.S.A)

Primary Mining Method

Sub-Level Longhole stoping.
Information
  1. Development of the ramp up to the desired elevation for the stope, top or bottom.
  2. Development of the access drift to the ore.
  3. Development of the lower and upper ore drifts.
  4. Once the development is completed, the panel is separated in sections of 21 m to 37 m (70 ft to 120 ft) long.
  5. Long-hole drilling for the initial cut. The drop raise consists in 19 holes.
  6. The long-hole drilling is completed for the stope.
  7. The drop raise is blasted in a single-shot and mucked out.
  8. The rest of the stope is blasted, 1814 to 2722 tons (2000 to 3000 short tons) at the time. The broken ore is completely mucked out after each blast.
  9. When the stope is completely blasted and mucked out, it is backfilled.
  10. The drilling of the drop raise is completed and the process is repeated for each following section.
Attached Documents

Secondary Mining Method

Longhole transverse.
Information
  1. Development of the ramp up to the desired elevation for the stope, top or bottom.
  2. Development of the access drift to the ore.
  3. Development of the lower and upper ore drifts.
  4. Once the development is completed, the panel is separated in sections of 21 m to 37 m (70 ft to 120 ft) long.
  5. Long-hole drilling for the initial cut. The drop raise consists in 19 holes.
  6. The long-hole drilling is completed for the stope.
  7. The drop raise is blasted in a single-shot and mucked out.
  8. The rest of the stope is blasted, 1814 to 2722 tons (2000 to 3000 short tons) at the time. The broken ore is completely mucked out after each blast.
  9. When the stope is completely blasted and mucked out, it is backfilled.
  10. The drilling of the drop raise is completed and the process is repeated for each following section.
Attached Documents

Gold Fields Ltd - Kloof Mine (South Africa)

Primary Mining Method

Sequential grid down dip.
Information

To deal with ground pressures, a V-shaped mining sequence is utilized. The main advantages of the sequential down dip method are the very low energy release rates, which make backfilling unnecessary, and the allowance for the physical separation of rock transport from men and materials. However, this has serious implications for ventilation: very large volumes of air are required as it is difficult to keep the airflow close to the face in the absence of backfill; and the return airways have to be cooled as they are used as travelling ways and the air exiting the stope would have gained heat while passing through the worked out areas.

STEP BY STEP

  1. Stope access by the footwall.
  2. Service raise with a length of approximately 320 m (1050 ft) and width of 12 m (39.3 ft).
  3. Stope mining from top to bottom. Ore removal by ore chutes located in the middle of the stope.
Attached Documents

Goldfields Ltd - Kundana Gold Mine (Australia)

Primary Mining Method

Long-hole bench stoping with backfill.
Information

The ore between each ore drive horizon is stoped using long-hole benching. Traditionally, Kundana has used the long-hole open stope benching, this is a simple retreat method which uses 10 m to 12 m (33 ft to 39 ft) holes drilled between the levels to break the ore leaving a void behind.

Holes are drilled up the dip of the orebody from one level to the next level. A slot is developed between the levels at the end of the ore drive. A series of long holes is then charged with explosives and blasted. The broken material is then bogged and transported to the stockpile using remote controlled Toro 151 loaders. Each blast produces 150 to 200 tonnes. The process is repeated retreating back towards the crosscut.

To aid in local ground control, small sections of the orebody are left intact to act as pillars. With this stoping method, the completed stope is left as an empty void, which over time has created some regional ground control challenges.

More recently, Kundana has employed a long-hole bench stoping method, which incorporates backfill. The orebody is divided into panels three or four levels high, the stoping sequence starts at the end of the bottom ore level using a similar method to the traditional method described above. When a section has been stoped out, the void is backfilled using broken waste rock from the decline and crosscut development. The level above is then stoped working on top of the fill. This method has all the advantages of the tradition method without leaving large voids therefore reducing the future ground control challenges.

Attached Documents

Hecla Mining Company - Lucky Friday mine (U.S.A)

Primary Mining Method

Overhand cut-and-fill.
Information
  1. The ramp is developed further than the crosscut stope access elevation.
  2. Access to the orepass is excavated.
  3. The crosscut access to the ore advances at -20%.
  4. The first cut of the stope is excavated by high drifting in the ore. Since the stope is accessed from the hanging wall, two active faces are available, one on each side of the crosscut. In consequence of the ramp longitudinally developed to the ore, the stope access is not always at the same place. Therefore, most often, one side is shorter than the other. Once the shorter side is completely excavated, the worker in that heading transfers in the ramp and continues the development.
  5. The stope is backfilled up to a distance of 0.3 m (1 ft) from the back.
  6. The crosscut is backslashed in order to reach the next lift elevation and the process is repeated to a maximum grade of +20%. The number of lifts, generally 3, mined from one crosscut depends on its length. The length of the crosscut is regulated by the thickness of the shear zone. In order to limit ground control problems, the development has to be kept inside the shear zone. Where possible, 5 lifts are taken from the same crosscut.
Attached Documents

Secondary Mining Method

Underhand cut-and-fill.
Information
  1. The ramp access is developed beyond the slot elevation.
  2. The crosscut access to the ore is advanced at +20%.
  3. The stope is mined by high drifting in the ore. Since the stope is accessed from the hanging wall, two active faces are available, one on each side of the crosscut. Due to the location of the crosscut, one side is shorter than the other. When the shorter side is completely excavated, the workers assigned to that heading transfer in the ramp in order to continue the development.
  4. The stope preparation for the backfill is achieved: 30 cm (1 ft) of waste rock, Dywidag installation, pipe installation and wall construction.
  5. The stope is backfilled to a distance of 0.9 m (3 ft) from the back.
  6. The crosscut access is benched in order to reach the next lift elevation.
  7. The stope is mined by breasting upwards using the waste rock as a void.
  8. The steps 5 to 8 are repeated up to a dip of -20% for the crosscut access. The number of lifts mined from one crosscut depends on its length, but, generally, there are 3 lifts. The length of the crosscut is regulated by the thickness of the shear zone. In order to reduce ground control problems, the development has to be kept inside the shear zone. Where possible, 5 lifts are taken from the same crosscut.

Homestake Mining Co - Homestake Mine (U.S.A)

Primary Mining Method

Mechanized Cut-and-Fill.
Information
  1. The access ramp is developed up to the desired elevation.
  2. The stope access is developed with a gradient of -18%. If the stope is narrow, the access is generally located at one extremity. This arrangement, in comparison with an access perpendicular to the stope, reduces the dilution caused by an over-excavation required for the equipment to travel. On the other hand, if a stope is well defined and long enough, the access is developed in the middle of the ore block, perpendicular to it. This way, two mining faces are available.
  3. Once the ore is reached, a first cut is excavated by sub-drifting up to the width of the ore.
  4. The next step is to backfill the opening. Depending on the availability, rockfill or hydraulic fill is used.
  5. The stope access is backslashed to the next lift elevation.
  6. Once the initial stope opening is created, the ore is blasted by breasting over the fill.
  7. The steps 4 to 6 are repeated until the stope access has reached a gradient of +18%. Then, the mining of the stope continues from a higher access.

Secondary Mining Method

Longhole open stoping.
Information
  1. Development of top and bottom sub-levels.
  2. Drilling and blasting of the slot raise. The slot raise dimensions are 1.8 m x 1.8 m (6 x 6ft). The upward raise is blasted in one shot.
  3. Cemented cable bridges are installed where brows are anticipated. A curing period of three days is required before blasting.
  4. The production drilling is done for the ore block. The maximum length for one block is generally 30 m (100 ft). A vertical pillar of 6 m (20 ft) is left before starting another block.
  5. The stope is blasted and mucked out. Most of the mucking is done using remote control equipment.
  6. A barricade is built under the pillar location and the stope is backfilled with hydraulic fill. The fill is poured into the stope through a fill hole and a breathing hole drilled directly in the open stope.

Homestake Mining Co. - Darlot Mine (Australia)

Primary Mining Method

Sub-level long-hole retreat with backfill.
Information

The narrow mining from the Walters zone represents only a small part of the production and is rather recent. The technical services are still working to calibrate the ideal dimension of a stope. Some stopes are opened more than two levels high thus creating dilution problems.

The common practice now involves the recovery of one level at a time retreating from the ends towards the centre. A maximum length does not seem to be established for the stopes. Some stopes were mined 110-m long (361 ft) before backfilling. This zone is mined from bottom to top and has not progressed much. More important stability problems are expected in the stopes to come.

The mining is relatively simple. First, the zone is accessed at the centre by crosscuts spaced every 20 m (66 ft). Drifts are then excavated in the ore from the crosscut up to the limits of the zone. The mining blocks are determined with geological information obtained from the development.

The long-hole mining begins by the excavation of an open raise. The drilling is done from the lower level and the blasting from the upper level.

When the raise is completed, the production drilling starts from the lower level. Then, the blasting sequence and the mucking begin and continue throughout the entire stope. When the excavation is completed, the backfill is brought to the stope.

Attached Documents

Normandy Mining Ltd - Bronzewing mine (Australia)

Primary Mining Method

Open stope.
Information

The particularity of this operation is definitely the exceptional quality of the walls. The mine is able to maintain an acceptable dilution even if mining narrow stopes leave longs holes open on several levels. The mining is relatively simple and progresses from top to bottom, leaving the stopes open.

THE DEVELOPMENT OF THE TWO ZONES IS DONE AS FOLLOWS:

  1. Two access ramps are developed, separating the deposit in two, 500 m (1640 ft) longitudinally per ramp.
  2. Crosscuts access the zone every 20 m (66 ft).
  3. Drifts are then developed along the vein.
  4. Reserve blocks are then identified and an open raise is developed for each block. When the development is completed, the production mining begins with a sequence of drilling, blasting and mucking.
Attached Documents

Normandy Mining Ltd - Jundee mine (Australia)

Primary Mining Method

Retreating Longhole.
Information

Up to now, the longhole mining for this mine was relatively simple, from retreating backfilled sub-level. The mine is developed from top to bottom and sub-levels were developed every 20 m (66 ft). Forward-looking challenge is to gain the same successful results for the gently dipping areas which are less than 40 degrees to obtain the reserves in the future levels.

Considering this, the technical services had prepared a mining sequence which is described in the attached document. The modified Avoca method with unconsolidated rock fill was selected. The spacing between sub-levels is 10 m (32.8 ft) vertically. Some interrogations remain about the mining method, particularly on the vein positioning during development, the stope mucking and backfilling. A scraper and water gun for the mucking cycle are expected to be used.

Attached Documents

Normandy Mining Ltd - Wiluna mine (Australia)

Primary Mining Method

Long-hole.
Information

The gently dipping veins (average of 40 degrees) represent the singularity of this mine. In addition to the gently dipping, the vein is cut by several faults, and consequently is discontinuous.

The retreating long-hole sub-level method is being tested in order to mechanize the mining operation. This method is quite simple. Initially, the lower and higher sublevels are developed. An open raise is excavated by conventional method. The anchor cables are installed in the hanging wall into holes previously drilled with a long-hole rig. Then, the production drilling is performed from the higher level as much as possible.

The problems occur during blasting and mucking.

The gently dipping veins cause difficult flow of the ore. To minimize the problems, the blasting is done with a maximum of 2 rows at once and the ore is entirely mucked out before the next blast. This approach gives good results. It is also possible to wash the ore from the higher level, but considering the height of the stope and the water pressure availability, only a small part of the stope can be covered.

The rock mass quality eliminates the requirement for backfill. Nevertheless, when the stope length reaches 20 to 25 m (66 to 82 ft), a vertical pillar of 3 to 5 m (10 to 16.4 ft) is kept in order to ensure wall stability.

Attached Documents

Secondary Mining Method

Room-and-Pillar.
Information

The room-and-pillar mining method is predominantly used since it allows the adjustment for sudden changes in direction of the vein. However, the management is endeavouring to introduce the long-hole mining method since the manpower for conventional mining is extremely rare.

First, the lower and upper sub-levels are developed at 17-m (56 ft) interval. Then, a raise is excavated, from one level to the next, to establish a ventilation system. The mining then starts by blasting the rooms of 6-m (20 ft) width. Pillars are left to stabilize the back. Usually, the ore recovery with this method is 80%.

Attached Documents

Sons of Gwalia Ltd - Golden Pig mine (Australia)

Primary Mining Method

Long hole open stope.
Information

The mine planning at the Golden Pig is very complex due to the variable geometry of the veins. It consists in developing a drift in the lower and upper points of curvature. The objective is to well-define the position and the geometry of the vein since diamond drilling does not give a precise interpretation. Sometimes, the spacing of sub-drifts can be as less as 6 m (20 ft). A maximum spacing of 15 m (49 ft) between the sub-levels is used, but usually the spacing is lower so that the average ore development represents 45% of the tons.

Further to a geological evaluation done from a borehole, the deposit is accessed by the main ramp. Then, for a same level, many ore drifts are developed to delineate the vein. When the definition is completed, the geological model is revised and planning of the production drilling is done.

Longhole drilling is performed with upholes. Usually, the upper level is developed but, occasionally, blind drilling is done.

The mining progresses retreating towards the access. Almost 100% of the mucking is done with a remote controlled scooptram. The broken rocks are sent to a muck bay from where it is taken to be loaded into trucks and brought to the surface.

Attached Documents

Sons of Gwalia Ltd - Yilgarn Star Mine (Australia)

Primary Mining Method

Long-hole sublevel retreat.
Information
  1. At first, the ramp will be developed to access the inferior limit of the zone.
  2. Four drifts are developed in the hanging wall. These drifts will allow to establish a ventilation circuit and to proceed with diamond drilling.
  3. Depending on the results of the drilling, sub-levels will be developed at intervals of 15 m (49 ft) or of 20 m (66 ft), intervals proposed in study.
  4. Raises will be developed in order to connect, at each extremity, the drifts of the hanging wall.
  5. The mining will be done from the bottom towards the top. A 20-m (66 ft) panel will be entirely mined and mucked before proceeding with the upper panel. The mining will retreat from both sides towards the centre where the access is located.

ADVANTAGES OF THE METHOD

  • The ore recovery is good since no crown pillar is required. Furthermore, the crown pillars originally planned every 25 m (82 ft) could be even more spaced or even eliminated if the conditions allow it.
  • The backfill serves as support.
  • The mined stopes are found in zones of active mining.
  • It is possible to drill with sufficient advance on the mining.
  • Production drilling could be done either towards the top or the bottom.
  • The mining activities and development are concentrated in the same sector.
  • The extraction sequence is simple and represents little risk

DISADVANTAGES OF THE METHOD

  • There is a delay in production during the development of the ramp to the inferior limit of the zone.
  • The stope must be backfilled before the production of the upper level may start.
  • A lot of the mucking has to be done with remote control equipment.
  • Constant supply of waste rock is required.
  • The production and backfilling are recurring operations.
Attached Documents

WMC Resources Ltd - Leinster Nickel Operations (Australia)

Primary Mining Method

Longhole modified Avoca.
Information

SLUDGE HOLE DRILLING
To enable greater delineation of the orebody, additional sludge drilling is undertaken. After each development drive has been completed, a comprehensive sludge drilling program is undertaken before any production model can be released for stope designs.

The sludge drilling is performed by a Solomatic drill rig. A ring of 3 vertical holes is drilled every 10 m (33 ft) along the development drive and the data is collected by a geologist.

The holes are between 5 to 15 m (16.4 ft to 49 ft) long. The holes are aimed to intersect the orebody contact, halfway between two levels. One hole targets the hanging wall, another hole targets the footwall and the third hole is driven up the centre of the massive sulphide orebody. The final hole design is left up to the geologist as the orebody can be variable.

Each sludge hole is also surveyed by a geological tool. This enables the geologists to accurately locate the rock types and thus provide a far superior geological production model.

MODIFIED AVOCA METHOD
The modified Avoca mining method was chosen for zone 1A. This method eliminates the requirement for a pillar when mining from bottom to top of the zone. Once mining has commenced in a level, mining will follow a typical cycle until that level is completely mined out. This method requires a lot of development prior to production. When the lower sublevels are developed, mining begins. First, open raises located at each extremities of the stope are excavated. Afterwards, the mining cycle involves the following activities:

  1. Drilling three downhole rings: 3.5 holes/ring, 65 m (213 ft) per ring, 195 m (640 ft) total drilling.
  2. Load and blast row 1.
  3. Muck row 1 (approximately 250 tons/section).
  4. Load and blast row 2.
  5. Muck row 2.
  6. Load and blast row 3.
  7. Muck row 3.

This 3-row cycle is repeated three times, resulting in an open stope of 18 m (59 ft) long, producing approximately 2250 tons. The length of this stope is established according to conception criteria and is less than the proposed length by the geotechnic department that suggests a maximum length of 25 m (82 ft). As mining proceeds, there are areas where the mining panel will be determined by the geology. Where the ground conditions remain good after the 18-m (59-ft) long mining panel has been extracted, further rings will be fired until geological and geotechnical conditions dictate otherwise.

Once the stope is completely excavated, the backfill cycle commences and involves the following activities:

  1. Install illumination light.
  2. Install wheel stop secured by resin bar Gewi bolts to floor, 2 m (6.6 ft) from crest.
  3. Backfill mining panel until the waste material has reached the crest (approximately 360 tonnes based on a 33 degrees rill angle).
  4. Remove steel bund.
  5. Create dirt bund.
  6. Recommence backfilling of mining panel over dirt bund (3000 tonnes of waste rock).
  7. Advance dirt bund forward as the mining panel is backfilled, keeping bund height at the minimum wheel height.
  8. Secure rolled conveyor belt to backfill.
  9. Crack the brow (1 ring, approximately 250 tonnes), ready for drilling next downholes.

Mucking the ore over a floor made of rock fill as well as blasting against the fill of the previous block causes a certain dilution evaluated at 13% on average. In a typical cycle, dilution is evaluated as follows:

  • Row 1: Dilution factor of 40% due to the blast against backfill.
  •  Row 2: Dilution factor of 30% due to the blast against backfill.
  •  Row 3: Dilution factor of 20% due to the blast against backfill.
  •  Rows 4 to 9: Dilution factor of 5% due to mucking on a backfilled floor.

The mining sequence and the extraction sequence are well illustrated with sketches (refer to attached documents).

Attached Documents

WMC Resources Ltd - Miitel Mine (Australia)

Primary Mining Method

Modified Avoca.
Information

GENERAL INFORMATION
The Miitel mine is actually in a development stage. The higher part of the orebody has been mined by the conventional cut-and-fill method. The lower part, the longhole modified Avoca method has been selected. A 17-m (55.7 ft) spacing between sub-levels is planned. However, part of the orebody was already developed at 25-m (82 ft) intervals between sub-levels. In these cases, three lifts will be mined with cut-and-fill method in order to obtain a 15-m (49 ft) spacing.

For the undeveloped part of the mine, the development and the mining are planned as follows:

The mining approach is to fully develop the known reserve and extract the orebody from the bottom up. This eliminates the need for leaving crown pillars and prevents the problems of possible stress concentration. The orebody has been divided into four blocks in order to create eight working faces. The accesses to these blocks are planned by limiting the retreat distance to 125 m (410 ft).

The majority of the orebody is being accessed via a main single ramp with a 1:7 gradient (-14.3%). This decline is designed to provide all access and ore haulage. The main entrance is located on the eastern flank of a 18-m (59 ft) high hill in order to take advantage of the local shallow base of oxidation and to limit environmental impact.

DEVELOPMENT

  1. Ramp: The ramp is located 60 m to 80 m (197 ft to 262 ft) of the mineralized orebody in the footwall.
  2. Muck bay for waste: Muck bays are developed off the main ramp at every 100 m (328 ft).
  3. Stope access: The access drifts are excavated from the main ramp in order to break into the mineralized orebody at 17-m (55.7 ft) intervals vertically. A muck bay is developed in each access.
  4. Ore drift: The orebody is open up to its limits on either side of the access.
  5. Ground support of walls: Prior to production works, cable bolts are installed in the hanging wall from the lower level.
  6. Slot raise excavation: A slot raise is required for each block located at the extremities of the orebody. Raisebores are sometimes used.

STOPE MINING
Blocks of 25-m (82 ft) maximum length are planned to be mined before backfilling.

Drilling: The drilling is performed from the top level.

Blasting: For blocks located at the extremities of the orebody, a raise is used as the initial opening. The subsequent blocks are blasted against the unconsolidated fill in order to create a free space. Part of the waste is drawn out, which allows to start the unwinding of a conveyor belt, placed after the backfilling, over the waste pile.

Mucking: A remote controlled scooptram allows the ore drawing in stope. The drawing stops when the conveyor belt is reached, which determines the limit between the ore and the waste. The ore is brought to a muck bay located in the access. It is then loaded into trucks by a higher capacity scooptram.

Backfill: The backfill is directly dumped in the stope from the upper level. When the opening is full, a conveyor belt is rewound and fixed to the back of the stope. The way the belt is positioned, it will unwind over the muck pile when part of the waste rock will be drawn out to create the required opening for blasting. This cycle is repeated until the level is completed. Then, the next level up is commenced working off the fill of the previous level. To obtain a flexibility and an acceptable production profile, a minimum of three levels needs to be developed.

Attached Documents

WMC Resources Ltd - Wannaway mine (Australia)

Primary Mining Method

Mechanized cut-and-fill stoping.
Information

The mechanized cut-and-fill stoping was selected to meet the following factors:

  • gently dipping
  • proper selectivity
  • poor quality of the hanging wall
  • narrowness of the zone
  • relatively short and irregular strike length.

DEVELOPMENT

  1. The decline (ramp) is located approximately 60 m (197 ft) in the footwall from the mineralization.
  2. Muck bays for waste rocks are developed off the main ramp every 100 m (328 ft).
  3. The stope access are located closest to the lens centre at 21-m (69 ft) interval vertically. A muck bay is excavated from the access adjacent to the main ramp. This first part of the access keeps a low dipping. To mine the block, the access is excavated with a ±1:7 gradient.

STOPE DESIGN EXCAVATION
Stope extraction commences from the central access working out to the boundary of the orebody. Following each blast, all the broken ore is mucked by a scooptram to the access stockpile. It is then loaded into trucks by a scooptram of higher capacity.

BACKFILL
Once the lift is completely extracted, a backfill line is surveyed and painted on the walls to indicate the required height. A scooptram is used for the waste rock placement from the extremities working back to the access. Where cement fill is required, broken rocks and cement are mixed in the adjacent muck bay which is excavated with a down gradient of 1:8.