Room Pillar Mining

Room Pillar mining is a method of mining that uses a room and pillar mining system.  The removal of coal in Room Pillar Mining is the method described to remove the coal in a series of wide areas, leaving pillars to support the roof.  It is possible to recover the pillars at a later stage to get the maximum benefit of extracting coal.

The Room Pillar mining equipment extracts the coal which is then transported by conveyer belts or other similar haulage equipment to transport the coal to the surface.  For a variety of seams Room Pillar equipment is highly productive, remote controlled and designed to accommodate different seams and mining conditions.

This diagram is a typical illustration of underground mining using Room Pillar Mining equipment.

The drying machine is a rotary metal drum, which is set atan angle of about 3-5 degrees and rotates at a speed of 2-8R/Min. the coal remains in the drum for 8-12min. The coal drum is uniflow which means the hot fuel gas and coal are fed in at one end and discharged at the other. The heat exchange takes place during the process of gas-solids concurrent flow in the drum.

Benefits of a Drum Coal Drying System

1. The process is simple and operation reliable.  If the factory is reasonably and compactly laid out as a whole with combination of feeding, crushing, drying and discharging, the total investment will be low and service life long.
2. The drying thermal efficiency is high compared with other drying systems.
3. The feeding quantity is adjustable with the sealed coal feeder. The coal flows fluent and unblocked.
4. Measures are adopted to collect the dust and prevent smoke at the drying drum, hot blast furnace and system transfer point. You will not see the air rebounded with dust and smoke.
5. Automatic monitoring system can monitor temperature and pressure at four points: furnace, dryer inlet, dryer outlet and inlet of induced draft fans which guarantee normal and safe production.
6. Big volume drum dryers are adopted to shorten the residence time of coal in the dryer to prevent coal burning and pulverization. In designing the drum dryer, we consider reliable performance, high capacity, high thermal efficiency, avoidance of caking, etc.
7. In designing the furnace, we consider easy ignition, quick heating, etc. In designing the dust collector, we chose deducting cyclone, which is high temperature resistant and without moving components, and high efficient pulse bag filter.

Coal Drying System Process Flow

Coal (Wet Basis) from Coal storage yard or coal mine is loaded onto belt conveyor and conveyed to sealing feeder for a direct feed into the JNG energy saving drum dryer.  After undergoing a process of medium heat exchange drying, the coal is loaded onto the discharging conveyor belt from the discharging box.  The coal is then conveyed to the storage yard.

Hot to medium (hot fuel gas) for coal drying is produced and prepared in a coal-fired hot blast heater.  The environment air, which is sucked into the flue pipe with an air blower and hot fuel gas from the hot blast furnace, is sent to the drum dryer after temperature adjustment where it heats the wet coal and absorbs the water vapour. The mixture of hot gas and water vapour go through a discharging box and flue pipe and is sent to dust collecting cyclone for powdered coal recovery. The preliminary purified gas is sent to the bag filter for further purification. Then the waste gas goes through the exhaust funnel and is discharged to the atmosphere by the induced draft fan.

The powdered coal collected by the First Stage dust collector is loaded onto the discharging conveyor by discharging spiral and sealed coal discharger, then mixed with the dried coal. The powder coal collected from the second stage bag filter, is loading onto the discharging conveyor by the discharging spiral.