Mining in Manitoba
Raises
Mine Development
Raise Cycle
a) Timbered Raises
A stoper drill is commonly used for drilling in a raise. The V-cut type of round is popular. Before blasting down the round, the timber below must be protected and the blasted rock must be directed into an orepass or chute. A common procedure is to direct the ore into a slide, which keeps the broken ore from dropping down the manway. The timbers that are directly exposed to the blast are covered with lagging. The round is then loaded and blasted.
After the blast, the loose rock needs to be cleaned away and water is used to control the dust. The loose rock on the back and sides must be scaled down. After the raise has been made safe, the manway slide is removed, a floor is built on top of the timber set, and the timber for the next set is hoisted and set in place where it is aligned and blocked tightly into position. The cycle is then ready to start again.
b) Raise Machines
A recent development in driving raises is the mechanical raise-climbing machine, which runs on a track fastened to the sides of the raise. It includes a drilling platform and a means of hauling supplies up the raise.
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When the climber gets to the top of the raise, the miners climb onto the deck, scale down the loose rock, and are ready to drill. When drilling is complete, another section of track is added and the climber is moved down to a protected position.
On this track is a row of teeth, which meshes with the gear on the raise climber. Turning the gear directs the climber up or down the raise. The climber is driven by compressed air.
c) Raise Bore Machines
Hard rock can now be cut with various types of rotary bits so drilling or boring large diameter openings has become practical. A raise boring machine drills a pilot hole to the level below. A drill rod or shaft is extended through the hole to the level below where a large diameter bit is fastened on.
The raise bore machine lifts the bit and creates a high force or thrust of the bit against the face while rotating the bit. The finished section is smooth and often support is not required.
