Raises and ore passes were used to connect different vertical mines


Raises can be used to link different vertical mine elevations with each other (Figure 3.40) Raises are used for various purposes, such as ventilation, ore passes, and travelways. Ore passes are typically designed with an angle exceeding 55° to the vertical in order to allow the broken rock to flow.
Through gravitational means. Modern mechanical techniques for raising in open stopping include longhole drilling and raise boring.


Longhole drilling involves drilling holes in a suitable pattern through the full depth of the ground, up to 60 m in some cases. Drilling is usually carried out from the top using conventional longhole drilling equipment. In certain instances, such as during top-down bench extraction, uphole drilling may be employed. Downhole raises are blasted in sections of approximately 5-10 meters, whereas uphole raises are blasted across their entire length, typically less than 25 meters.

Raise-boring machines are capable of raising raises with a sufficient diameter and height to match any stopping or mining development requirements. Although the cost per cubic meter of rock removed is higher than conventional drill and blast methods, this type of development offers speed in advance. 

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For mine ventilation, raise boring is particularly important. Decline development can be undertaken blindly and with increasing depths owing to exhaust ventilation by raise-bored ventilation shafts. They have a smooth-walled finish, which reduces air resistance.

Fill infrastructure with infrastructure filling.

Fill masses are required to provide large-scale ground support and localized stability for pillar recovery. The key stages of a sublevel stop operation are material and stope preparation, fill delivery or reticulation, placement, and drainage. The development of fill delivery and reticulation is usually addressed during the stope block design. The alternatives may include fill delivery from a surface material station via raise holes or boreholes, truck delivery to stopes via ramp access, or from underground sources.

Underground fill reticulation is accomplished through gravity feed or pumping to areas that have been stopped out. Conveyor belts, pipeline distributions, or standard or ejection tray trucks may be employed. For large orebodies, fill reticulation usually requires long-term development within the crown of the orebody. Crown subsidence may, in such cases, threaten the stability of the development associated with a fill system above an orebody. In order to minimize this likelihood, progressive tight filling of stope voids is required, as the combined effect of unfilled stope crowns can result in regional subsidence. Geological and operational factors, such as delaying filling, can influence the rate of subsidence.

Large unfilled voids and progressive stopping may cause dilation of geological discontinuities, which in turn can be linked to rotation and sliding of large blocks within the crown of a deposit. This localized block behavior may result in significant variations in the relative elevations along the strike of an orebody. It is possible to obtain an understanding and manage subsidence through continued monitoring using precise level-surveying techniques.

The scheduling of long-term productions.

Production scheduling is the highest level of scheduling and focuses on issues such as ore grade, extraction sequences, and production quantities. Production schedules typically extend over a number of years and are expressed in terms of ore sources related to stopping blocks (Trout, 1997) These schedules have the potential to extend throughout the lifespan of a mine, contingent upon the preceding event. A scheduling exercise includes long-term production targets, fill, development, raising, and diamond drilling requirements. Annual estimations for equipment replacement, capital expenditure, and operating expenditure may also be determined. The most prevalent constraints imposed on scheduling may encompass capital availability, anticipated life of the mine, infrastructure, and equipment life.

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