Coal Age

JUL-AUG 2018

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July/August 2018 21 monster wall continued for any advantage that will yield a lower cost per ton. And, that's especially im- portant in a region where coal competes directly with natural gas. "For coal com- panies to survive, they must continue to reinvent themselves," Yackuboskey said. "That's what this Monster Wall discussion is all about. It's about evolution, looking toward the future with a vision of pro- gressing to new possibilities." Longwall mining has advanced a great deal since his fifth-generation ancestors began the practice in Europe. Today's longwall systems employ automated roof supports (shields) and shearers and pro- duce massive amounts of coal. For sever- al years now, longwall mining in the U.S. has been the leading method for under- ground coal production with more than 50% of the underground tonnage. Some highly productive longwall faces average 3,500 tons per hour (tph) with coal re- covery rates between 80%-90%. Longwall systems represent a significant capital in- vestment and they usually offer good re- turns on that investment. CONSOL Energy has three longwall mines: Harvey, Bailey and Enlow Fork. Lo- cated in southwestern Pennsylvania, each of the three mines operate two longwall faces and all of the coal feeds into the Bai- ley Central prep plant. "The first longwalls at the Bailey Complex had 600-ft faces," Yackuboskey said. "Those faces grew to 750 ft and eventually to 1,100 ft in early 2000s. Now we run 1,500- to 1,600-ft long- wall faces." After explaining this line of evolu- tion, Yackuboskey introduced the 2,000- ft Monster Wall concept. "The longwall face would consist of 300 2-m shields," Yackuboskey said. "The panel would re- quire 50 blocks of development and it would hold 6 million clean tons of coal once its established." The preliminary CONSOL Energy de- sign was based on Cat 2-m shield. Yacku- boskey leans toward Cat equipment and he believes the company offers the tech- nology to accomplish the feat. His vision for the Monster Wall is one that produces consistently at more than 3,000 tph with a shearer that trams at speeds of 39 feet per minute (fpm) from the headgate to the tailgate and 33 fpm from the tailgate to the headgate. "The Monster Wall would generate a steady black river of coal," Yackuboskey said. Why 2,000 ft? CONSOL Energy's longwall panel lengths vary from 12,000 ft to 15,000 ft. Speaking in round figures, Popp explained that a 2,000-ft-long longwall face would pro- vide 33% more coal compared to a 1,500- ft face. "If an operation is averaging 4.5 million clean tons per panel, they could expect to produce 6 million clean tons on average per panel. The longer face would provide more time for the shearer to cut coal before it reverses direction." Popp doubted it would be much dif- ferent from making the leap from 750 ft to 1,100 or 1,100 ft or 1,500 ft, it would just have to be planned as well. "Three 2,000-ft longwall panels would replace four 1,500-ft faces, which means one less entire gate section would have to be developed over the course of three panels and there would be one less longwall move." Another consideration is district siz- es. If a coal company was only allowed six panels in one district, it would gain two 1,500-ft faces in the same district. "We could also spread the cost of the tailgate section and bleeders across 36 million cleans tons rather than 27 million tons," Popp said. "This is why we stretched the faces in the first place." For those gate sections, Popp esti- mated a development cost of at least $6 million every three years. "We can add 500 ft to the longwall for about $92,000 to go from 1,500 ft to 2,000 ft," Popp said. "To develop the start line, it would be an additional 500 ft across the face and bleeder entries. At 70 ft per shift for a three-entry bleeder system, that's an extra eight days of mining — that's a small cost for an additional 33% of coal. If we compare that to the cost of another Armored Face Conveyor Chain Size Wieght Tons for (lb/ft) 2,000 ft 48 mm 31 136 52 mm 36 144 56 mm 40 160 60 mm 44 176 Power Calculations Horsepower 3 Face Motors 2,600 Shearer 1,666 4 Kamat Pumps 0, 300 Stageloader 0, 460 Crusher 0, 460 ISE Pumps 0, 150 Total Horsepower 5,636 Amperage 350 MCM 0, 500 500 MCM 0, 630 1,500-ft face 0, 463 2,000-ft face 0, 544 Horsepower Calculations for 2,000-ft Longwall Face (3 x 2,600-hp, 0° grade and 56-mm AFC chain) Cutting Sequence BI-DI BI-DI BI-DI BI-DI Cutting Direction HG-TG TG-HG HG-TG TG-HG Shearer Speed (fpm) 39 33 47 38 Face Length 2,000 2,000 2,000 2,000 Total Mining Height 108 108 108 108 Base Web Depth 42 42 42 42 Coal Block Density (lb/cu ft) 89 89 89 89 Coal Broken Density (lb/cu ft) 57 57 57 57 Face Conveyor Discharge Rate (tph) 3,000 3,000 3,000 3,000 Required Cross-sectional Area 4.43 4.43 5.17 5.17 Conveyor Speed (fpm) 394 394 394 394 Total Applied Power 7,800 7,800 7,800 7,800 Full-length Load for Running Hp 7,593 7,181 9,152 8,529

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