HEADGEAR STRUCTURE
It is a steel or concrete frame work on the shaft mouth.
The headgear consists of nearly, vertical columns which is two front legs columns, two main leg columns & two back legs columns. Which is inclined at 1 in 8 to 1 in 10. towards the winding engine room.
HEADGEAR PULLEY.
The angle of fleet which is the angle between the vertical plane of the pulley and the rope when the cage is at pit-top or pit-bottom, should not exceed 1.5 degree
The overturning or Kimberly skip has both positive and negative aspects associated with it.
It is able to handle large sized muck with low spillage.
 |
| HEADGEAR STRUCTURE |
It is a steel or concrete frame work on the shaft mouth.
The headgear consists of nearly, vertical columns which is two front legs columns, two main leg columns & two back legs columns. Which is inclined at 1 in 8 to 1 in 10. towards the winding engine room.
The vertical and inclined legs are joined by horizontal girder.
The top of the headgear has a steel platform, or plate & the bush bearing of the winding pulleys, rest on the vertical numbers of headgear frame.
Above the banking level, there is a detaching plate or detaching bell which is fixed in the headgear structure.
This detaching plate is fixed at the height of length of cage + length of cage suspension gear + 3 to 7 m.
This margin of 3 to 7 meter allows a cage to be lifted for materials, to be slung, beneath it.
Above the Detaching plate there is a headgear pulley which is fixed at the top of the structure and the winding rope is passed over the headgear pulley.
Where, the one end of the winding rope is connected to the winding drum which is situated in winding engine room. And another end of the rope is connected to the cage suspension gear.
The diameter of the headgear pulley should be 100 times more than the diameter of the winding rope.
The purpose of headgear is
To support the headgear pulleys.
To support the weight of hoisting ropes.
To support the cages & to rope guides.
To guide the cage to the banking level.
The height of the headgear is decided by considerations which are as follows:
1)Number of decks on the cage.
2)Banking level. (Banking level is the platform, where cage is rest in headgear structure.)
3)Pit-top layout.
4)Depth of shaft.
5)Diameter of shaft.
6)Size of the cage/skip.
7)Rate of acceleration & retardation.
8)Height of the cage.
9)Inspection platform.
10)Diameter of headgear pulley.HEADGEAR PULLEY.
 |
| Headgear Pulley |
It is made up of hard steel.
The headgear pulley’s diameter is such that it should minimize the bending stresses in the winding rope.
Generally its diameter is 100 to 120 times diameter of the rope.
The large size pulleys are made in two parts and bolted together.
The grove is made of renewable soft steel & its diameter should be 110% of the rope diameter for stranded ropes & 105% for locked coil ropes.
Its construction should be such that its weight is less.
 |
More fleet angle results in wear of the rope and wear of the pulley also.
CAGE
It is a lift like structure suspended from winding rope by means of suspension gear arrangement.
It is used for the transportation of men & materials.
It is made up of steel and very strong in construction.
A track is provided on the floor with catches to prevent the movement of the tubs.
It is open with two sides & provided with collapsible door.
Man travelling in cage provides a hand bar on the sided for holding.
Types of cage:-
a)Single deck single cage
A cage which can accommodate only a single tub is called a single cage.
b) Tandem cage
A cage which can accommodate two tubs or more in one cage is called tandem.
c) Double deck single cage
A cage which can accommodate one tub on each floor.
d) Double deck tandem cage.
A cage which can accommodate two or more tubs on each floor.
SKIP IN UNDERGROUND MINE
SKIPS are generally used for coal or minerals transport only, but in new construction type the men can also travel in the upper portion of the skip.
It does not accommodate tubs, but coal or mineral is directly filled in the skip through its top opening.
Skips travelling in the vertical plane have a discharge opening at the bottom for unloading the mineral content.
Its capacity is very high.
If the minerals is of different grade then mixing of mineral and degradation of mineral is a problem.
There are some different types of skips in mining which are depending on the requirements of the mine, which are
1)overturning or Kimberly. 2)swing out body or front dump.
3)bottom dump
Overturning or Kimberly.
 |
| Overturning or Kimberly. |
It is able to handle large sized muck with low spillage.
Some of the negative aspects are that is often has material that sticks to the bottom during the unloading of the ore or waste.
It is constructed with a large head frame because of the high stresses incurred. This often results in a small payload relative to the size of the skip.
Swing out body or front dump
 |
| Swing out body or front dump |
The swing out or front dump skip has both positive and negative aspects associated with it.
This type of skip has the ability to handle a large payload.
It has a relatively small head frame and is easy to empty.
Some problems that often arise with this type of skip are a build-up of muck at the hinge point and slimes drip out of the bottom.
Also the door mechanism is complex and occasionally makes maintenance issues difficult to fix in a timely manner
Bottom dump
 |
| Bottom dump |
The fixed bottom dump is the most versatile type of skip.
It easily can convert from a skip to a cage.
While in skip form it can carry a large payload and has a relatively small head frame.
In the dumping mechanism no scrolls are needed.
With this type of conveyance fixed guides or rope guides are often required
SKIP VS CAGE WINDING
Skip winding is best suitable for deep shafts where high output is desirable.
The ratio (𝑝𝑎𝑦𝑙𝑜𝑎𝑑 )/(𝑔𝑟𝑜𝑠𝑠 𝑙𝑜𝑎𝑑 𝑜𝑓 𝑙𝑜𝑎𝑑𝑒𝑑 𝑠𝑘𝑖𝑝) is high. Nearly 0.6 in skip winding but, with skip winding the ratio is only 0.35.
With a skip installation, the number of mine cars used underground is less as they are not raised to the surface moreover such mine cars are independent of the size of the shaft or skip.
Skip lends itself to automatic loading unloading and decking operation.
Less manpower required for skip installation.
Trackless mining is possible from the working face right up to the surface .
Skip winding has however the disadvantages that separate arrangements have to be made for winding for men and material.
With skip winding it is difficult to import dirt, washery refuse or mill tailings for underground packing of goaf or stope.
Degradation of mineral, particularly soft mineral like coal, takes place during loading and unloading of skip. And to prevent coal dust from entering the mine it is essential to install the skip in U.C shaft.
A higher headgear is essential and shaft has also to be sunk deeper than the level of the mineral bed, as compared to cage winding.
The ratio (𝑝𝑎𝑦𝑙𝑜𝑎𝑑 )/(𝑔𝑟𝑜𝑠𝑠 𝑙𝑜𝑎𝑑 𝑜𝑓 𝑙𝑜𝑎𝑑𝑒𝑑 𝑠𝑘𝑖𝑝) is high. Nearly 0.6 in skip winding but, with skip winding the ratio is only 0.35.
With a skip installation, the number of mine cars used underground is less as they are not raised to the surface moreover such mine cars are independent of the size of the shaft or skip.
Skip lends itself to automatic loading unloading and decking operation.
Less manpower required for skip installation.
Trackless mining is possible from the working face right up to the surface .
Skip winding has however the disadvantages that separate arrangements have to be made for winding for men and material.
With skip winding it is difficult to import dirt, washery refuse or mill tailings for underground packing of goaf or stope.
Degradation of mineral, particularly soft mineral like coal, takes place during loading and unloading of skip. And to prevent coal dust from entering the mine it is essential to install the skip in U.C shaft.
A higher headgear is essential and shaft has also to be sunk deeper than the level of the mineral bed, as compared to cage winding.
WATCH VIDEO
Skip And Cage in u/g mines
TO WATCH MORE MINING RELATED KNOWLEDGEABLE VIDEOS
CLICK ON BELOW LINK
Comments
Post a Comment