Study of Raise Drivage Methods (UMM- Practical No.1)

1.     STUDY OF RAISE DRIVAGE METHODS.

Raise is an underground opening driven upward from lower level to upper level or one level to a higher level or to the surface; a raise may be either vertical or inclined. Raising is a regular operation in the development of underground metalliferous mines.

(a)   COMPARTMENT METHOD

Introduction

Initial excavation made from the lower level in the direction of the raise for 2 m, and then the raise is divided into Two or Three compartments.

Application: Vertical or very steep raise, Up to 15-20 m

RAISING WITH 2-COMPARTMENT METHOD:

            Raising with shallow holes is started by cutting out a recess at the bottom level, from which subsequent operations are performed. Work is done from stage sited 1.8-2.0 m from the face. After firing a round of holes the stage is advanced towards the face. The working stage rests on two or three stull temporarily set into holes made in the walls of the raise. It consists of wooden planks laid over the stulls. Holes are drilled from the stage by means of stopers. After the drilling is completed the drilling equipment and the tools are removed from the face and the holes are charged with explosives. Before firing/blasting, the ladder way of the raise is covered by inclined thick wooden planks which guide the broken rock away into rock compartment. After blasting, the face is cleared of smoke and the miners inspect it and dress down loose pieces of rock, while standing under protection of the stage. Then the timber sets are erected and the working stage is transferred closer to the face. As the face advances, the rope ladder connects the upper ladder sollar with the working stage.

Cycle of Operation:

Inspection and dressing down the loose rocks, timbering, extending the ladder way, construction of working stage and drilling, removing the working stage, charging, firing/blasting, and clearing the smoke

RAISING WITH 3-COMPARTMENT METHOD:

This method is same as two compartment method. In this method initially the area is divided in two. One area is used as ore pass. The second half area is further divided in two parts. One part is used as ladder way and other used for conducting the pipe lines and cable. The drilling-blasting and removal of the blasted material of the raise are carried in the same way.