CONTINUOUS MINER

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INTRODUCTION Continuous miner is a machine designed

to remove coal or other soft minerals from the face and to load it into cars or conveyors continuously, without the use of cutting machines, drills, or explosives.

Hence It produces a constant flow of ore from the working face of the mine.

It can mine as much as five tons of coal a minute – more than a miner of the 1920s would produce in an entire day. Continuous miners account for about 45% of underground coal production.

APPLICATION Majorly continuous miners are used in

coal mines for extraction of coal. They are typically used when board and pillar type of mining method is followed. They are used for production of coal as well as for depillaring purpose in board and pillar mining of coal.

Apart from coal these machines are successfully operating in Trona (trisodium hydrogendicarbonate dihydrate), gypsum, potash and salt mines around the world.

COMPONENTS The main components of a continuous miner are-

• Cutting Drum• Boom• Hydraulic cylinder for boom actuation• Gathering arm loader• Chain conveyor• Apron • Crawler unit• Electric Motors• Leveling jacks• Body/Frame

A WORKING CONTINUOUS MINER

THE CUTTING DRUM

THE CUTTING DRUM The cutting drum faces the coal face.

The drum is rotated by electric motors. The drum is responsible for the cutting of coal. It consists of –

o Cutting picks- made of tungsten carbide.o Cutting tool holders-to hold the picks.o Water spray-The continuous miner may

consist of water spray behind the picks.

BIT/PICK HOLDER

WATER SPRAY

The continuous miner may have a fine spray behind each cutting bit on the cutter drum which potentially removes friction ignition occurrence and maintains respirable dust levels. The water spray acts as both cooling and wetting agent in order to control both problem at one time. The spray also provides lubrication hence increasing bit life.

SPRAY MAY HAVE THE FOLLOWING FEATURES AND CORRESPONDING BENEFITS

THE BOOM The boom contains the drum. It can be

moved up and down by hydraulic actuators.The coal face is cut from top to bottom. The boom is made up of high strength alloy steel.

THE GATHERING ARM LOADER Continuous miner consists of loader

featured two arms attached to the front of a short conveyor belt. The arms moves in a wide sweep, gathering loose coal and scooping it onto the conveyor belt, which then deposits the load into a shuttle car.

CHAIN CONVEYOR Continuous miner consists of a central

chain conveyor which conveys the gathered coal of the gathering arm loader to the shuttle car.

CRAWLER UNIT Continuous miner consists of crawlers

for its movement. The crawlers are also driven by electric motors.

MOTORS The continuous miners use individual

motors with direct drive transmissions to power the cutter, traction, gathering and hydraulic systems.

TOP VIEW OF CONTINUOUS MINER

SIDE VIEW OF CONTINUOUS MINER

TYPES OF CONTINUOUS MINERS Auger head continuous miner Borer-type continuous miner Drum head type continuous miner Oscillating head ripper miner Remote-controlled or robotic miner Ripper-type continuous miner

LEADING MANUFACTURERS Bucyrus International Joy Mining Machinery Siemens Sandvik

PRODUCTIVITY/AVAILABILITY The economics of operation in parts cost

per ton of material produced is an essential factor in the selection of miner

TODAY’S REMOTE-CONTROLLED AND ROBOTIC MINERS Today’s miner can extract at least 38

tons of coal per minute, depending on the thickness of the seam, although manufacturers are constantly beating the record.

Modern day continuous miners are remote-controlled and customized for different mining conditions. The number of robotic miners operated via computer controls is increasing, eliminating the need for an operator in this sometimes dangerous task.

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ON BOARD DUST COLLECTORS An electrically driven fan connected to

machine mounted ducting system picks up the dust at the cutter head. It is then exhausted and collected on a filter screen. Downstream, a de-mister mounted in the ductwork separates the water from the air, allowing clean dry air to be exhausted at the rear of the miner.