Washing Section
Sized Raw Coal from the existing Crushing and Screening Facilities shall be transported to a Surge Bunker. From the Surge Bunker, Coal [(-) 50 mm] shall be delivered into a Coal Wetting Launder where water shall be added to the Coal. The slurry then shall flow through Launder to a set of Desliming Sieve Bend and Screen
to remove minus 1 mm coal fines from the coal. The coal slurry collected from Desliming Sieve Bend and Screen under pan shall gravitate through pipes to a Fine Coal Tank.
The Deslimed Coal [Coarser fraction of (-) 50 to (+) 1 mm] shall go from Screen Discharge Chute to the Launder. The Magnetite media of required specific gravity shall be added at the back of the launder to get mixed with the coal and simultaneously to push the mixture of Magnetite & Coal Slurry into the Central
column provided in the centre of the Heavy Media Tank.
The Coal & Magnetite mixture from the Centre Column shall be pumped by a Heavy Media Cyclone Feed Pump to feed Heavy Media Cyclone. The Cyclone shall have Overflow and Underflow. The Clean Coal, along with magnetite media, shall be received as overflow from the Cyclone and be fed to a set of Clean Coal Sieve Bend and Clean Coal Drain & Rinsing Screen. The Magnetite media shall be drained through sieve bend and first part of the screen and be collected in the dense under catch pan of the screen. The same shall be re-circulated back to the washing system. The carried away Magnetite with the Coal Particles shall be removed by Water Spraying in the discharge part of the Clean Coal Drain & Rinsing Screen. The
Magnetite removed from coal by water spraying shall be collected in the dilute catch pan of the screen as dilute media and be taken to Dilute Media Tank. The overflow of this screen shall be dried in a Horizontal Basket Centrifuge and then collected as Clean Coal by Belt Conveyors and transported to a set of Product Bunkers. A Sizing Screen mounted on the Product Bunkers shall separate [(-) 50 (+) 25 mm] and [(-) 25
mm] fractions of the Clean Coal for separate storage in the Product Bunkers from where the same shall be transported to the respective customers.
The underflow of Heavy Media Cyclone treated as discard shall be fed to a set of Reject Sieve Bend and Reject Drain & Rinsing Screen. The magnetite media drained through sieve bend and first part of screen and be collected in the dense under catch pan of the screen. The same shall be re-circulated back to the washing system. The carried away Magnetite shall be removed by Water Spraying in the discharge part ofthe Reject Drain & Rinsing Screen. The Magnetite removed from rejects by water spraying shall be collected in the dilute catch pan of the screen as dilute media and be taken to Dilute Media Tank. The overflow of this screen shall be collected as Rejects by Belt Conveyor and transported for ground storage and weather drying.
The Fine Coal Slurry collected in the Fine Coal Tank shall be pumped into a set of Classifying Cyclones. The underflow of classifying cyclones shall be dewatered in High Frequency Screen. The underflow of High Frequency Screen shall be transported back to the Fine Coal Tank while the overflow of the High Frequency
Screen shall be collected and mixed with Clean Coal and transported to the ground
storage. The overflow from classifying cyclones shall be fed to a High Rate Thickener. Flocculants shall be used in Thickener to facilitate Settling process. The thickened slurry from Thickener shall be pumped to a Multi Roll Filter Belt Press for recovery of coal fines. Alternatively, during breakdown of Thickener, the
thickened slurry may be transported to a series of Emergency Settling Ponds.
Clarified water from the Settling Ponds shall be pumped back to the Clarified Water Tank adjacent to the Thickener wherein Make Up Water shall also be added for circulation into the system.
