METHOD FOR COATING LOW-GRADE COAL

PURPOSE:To prepare low grade coal which is prevented from spontaneous ignition and is dehydrated at low cost, by spray coating dried low-grade coal in granules or in powder with a paste consisting of pulverized anthracite and water-soluble starching material, followed by redrying. CONSTITUTION:A small amount of water is added to mined brown coal 1 to produce a 1:1 mixture and the mixture is crushed (18) by means of a wet crusher to the particle diameter of 1mm. or smaller. The aqueous slurry of crushed brown coal 1 is introduced into pipe line for shipment to consuming cities or shipping points (19). The slurry is dehydrated by screening, etc. (20) and is led into an inner cylinder of a rotary drum drier 2 by means of a screw feeder 10. The brown coal is dried in the first drying zone 7 and spray coated in the coating zone 8 with a paste 13 consisting of pulverized anthracite from a conditioning tank 12 and water-soluble starching material. The coated coal is dried in the second drying zone 9, fed into a hopper 11, carried to a stock point by belt conveyer, etc. and is stored in the open air or in silo, etc. (21).