A raise borer is a machine used to create bores, or holes, between two existing levels of a mine. These holes are often referred to as raises, and are generally used for conveyance or ventilation purposes. The raise borer can be used to create vertical raises or bores along a slope or angle. Compared to traditional blasting techniques, raise boring provides many advantages in terms of safety and mining productivity.
In a standard boring application where a hole is being bored between two levels in a mine, the raise borer will be placed on the higher of the two levels. Using a hydraulic engine, the machine first drills a pilot hole down from the top to the bottom level. A boring unit known as a reamer is placed beneath this pilot hole on the lower level and connected to the raise borer using a series of cables. Using hydraulic pressure, the raise border raises the reamer to create a bore hole between the two levels, cutting through dirt and rock.
Sometimes, the uppermost of the two levels may be too small to accommodate the raise borer. In this application, a special boxhole raise boring machine is used. The boxhole is placed on the lower level, and used to drill a pilot hole up to the top level. The reamer is attached to the raise borer with hydraulic pistons, and the borer pushes the reamer up to the top level from below. While this device provides an effective method of boring in smaller mines, it also poses added risk to miners and equipment operators.
Raise boring serves as an alternate to traditional blasting, which relies on explosives to create raises and bore holes. While blasting tends to be unpredictable, raise boring allows for controlled boring. The position of the reamer protects workers from falling rocks or debris, and there is no risk of fire or fumes like those associated with blasting. Finally, raise boring allows for safe and effective shaft creation in areas where the land is too unstable for explosives.
In addition to its many safety benefits, raise boring also provides many other advantages to miners and mining companies. The walls of the bore created by a raise borer are smooth and consistent, and there is no need to add reinforcement or structural support in most cases. Raise boring also allows raises to be created much more quickly than blasting. Using different types of reamers, the size and shape of the bore is virtually unlimited, allowing for flexibility in mine design and operation.