The Greenwich Collieries Co. is a subsidiary of the Pennsylvania Mines Corporation, and a wholly owned subsidiary of the PP&L Co. which serves the northeastern portion of Pa. PP&L annually consumes about 11 million tons of coal per year and is the largest consumer of both bituminous and anthracite coal on the eastern seaboard.
Sulphur content of Greenwich coals are all high in pyrite (average 85%) and low in organic-sulphate sulphur (average 15%). The high concentration of pyritic sulphur is found in rather large particles, partings and discontinuous lenses throughout the seam mass.
The +4 inch material is scalped off to refuse, on two 8′ x 20′ AC screens. The 4″ x 0 material is fed to the screenhouse on two 54″ belts and reports to five 250 ton raw coal bunkers or to the 12000 ton emergency raw coal open storage. Coal is evenly distributed to the five bunkers by a traversing 54″ chain driven tripper.
The fine ¾” x 0 raw coal is conveyed to a transfer point via a 48″ transfer belt. At the transfer point the 1200 tons per hour flow passes through a splitter gate where all or any part of the total flow can be diverted to the new plant or bypass to the clean coal loadout area. The amount of coal, bypassed to loadout or conveyed to the new plant depends on the quality of the raw coal fines.
From the 100-ton, two-compartment surge bin, raw coal is fed into the five meter wide (16.5 ft.) “Batac” jig via two general kinematic 6′ x 6′ adjustable rate 350 ton/hour remotely controlled stainless steel lined feeders.
At this point the raw coal is wetted with water sprays that add about 1200 GPM to the raw coal feed. The thoroughly wetted ¾” x 0 coal is fed into the “Batac” jig at a nominal rate of 600 tons/hour (750 ton/hour has been fed with only a slight decrease in operating efficiency). It should be noted that the jigs were originally designed to process ½” x 0 raw coal, however, our deteriorating ROM product required a change to ¾” x 0.
The jigs are 5000 millimeters (16.5 ft.) wide x 6200 millimeters (20.5 ft.) long with a jigging surface of 30 square meters (326 sq. ft.). The “Batac” jig is a 6 cell 2 compartment machine with the last cell in each compartment equipped with a feldspar bed to increase the cleaning efficiency of the finer particles. The jig rejects from both the primary and secondary refuse elevators are dewatered in vibrating centrifuges.
The plant is equipped with two Heyl-Patterson model 170 fluid flow thermal dryers containing Research Gottrell high energy scrubbers. Each dryer has the versatility of operating independently on either circuit. Each of these dryers has an evaporation rate of 50 tons of water per hour. Nominal coal flow is 535 to 550 tons per hour..
Both jigs have required a minimum of maintenance during this first year of operation. We have frequently fed at an average rate of 700 TPH (750 TPH max) to each jig without any noticeable difference in performance.
