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.

Continuous Miner

CONTINUOUS MINER

Powerpoint Presentation

        



Continuous Miner - Video

Categories: Mining Machinery II

Bord and Pillar Coal Cutting Machine

COAL CUTTING MACHINE

Introduction:
Coal cutting machine is used in bord and pillar mining method of underground coal mining to make Undercut, Overcut or Middlecut to provide free face for the blasting operation.

Development by CCM:
The headings are Undercut, Overcut or Middle Cut by a coal cutting machine and shot holes are then drilled and charged with explosives and blasted. Blasted coal is hand loaded on to scraper chain conveyors which transport the coal from the face to a central belt conveyor.

Construction:
Coal cutting machine may be under-cutting, over-cutting or middle-cutting types. Commonly, undercutting chain type coal cutting machines are used. In watery mines middle-cutting or over cutting machines are preferred. Where roof is to be a formed overcutting machine are employed. Normally a machine gives an undercut in a heading of 4.2 m width in about 15 minutes. But, their overall performance depends on the organization to secure higher utilization. In India, the average output per coal cutter per month in 1980 was of the order of 2500 tonnes.

Coal cutting machines are powered by electric or air motors. The electric motors may be operated by A.C. supply or by D.C. supply at 550 volts. The power is supplied through 4/5 core trailing cable of 91.44 m length which is carried in the body of the machine. Air motors are run by compressed air at 3.51 kg/cm¬2 at the face requiring 0.7079 m3 of air per B.H.P. The rpm of the air turbine is between 1500 to 2000 and the hp developed is 40-60 hp.

FIGURE 1

The other types of coal cutting machine especially designed for bord and pillar working are: (1) Arc-Shearing (Arcwall-and-shearing) coal cutters and (2) Arcwall coal cutter.

ARCWALL AND SHEARING COAL CUTTERS

FIGURE 2

The Arcwall and Shearing coal cutters (Figure 2) are designed to give cut on the face in any direction. They can undercut, overcut or make vertical or oblique shearing cut. They are normally used for driving narrow working but under suitable conditions they can take slabbing cuts off the side of pillars.
The Arc-shearing machines may be track mounted or crawler mounted.


ARCWALL COAL CUTTERS
The arcwall coal cutters (figure 3) make their cut in a plane parallel to the rails they stand on or the floors their crawlers rest on. The machines can also sump in or out, keeping the jib at a constant angle.

FIGURE 3

-------------------------------------------------------------------------------------------------------------------

COAL CUTTING MACHINE POWERPOINT PRESENTATION

            


HOW TO DOWANLOAD PPT

Click on the setting button    in ppt and Download as PPTX.

Categories: Mining Machinery II