Identifier: coalmininginilli13andr (find matches)
Title: Coal mining in Illinois
Year: 1915 (1910s)
Authors: Andros, S. O Illinois State Geological Survey University of Illinois (Urbana-Champaign campus). Dept. of Mining Engineering United States. Bureau of Mines
Subjects: Coal mines and mining
Publisher: Urbana, (Ill.) : University of Illinois
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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Text Appearing Before Image:
I I Fig. 15. Shearing the ribs in District VII at intervals of 500 to 600 feet along the cross-entries pairsof room-entries, often called panel entries, are tinned off at aright angle to the cross-entries. The solid pillar of coal be-tween the cross-entry and the first room, called the cross-barrier pillar, in Illinois varies in width from 20 to 150 feetand averages 56. The main barrier-pillar which is the coalleft between the main entry and the ends of the rooms turnedoff those room-entries which are nearest to the main entry,varies in width from 20 to 150 feet, averaging 68. The num-
Text Appearing After Image:
Fig. 16. Plan of panel mine MINING PRACTICE 85 ber of rooms on a room-entry varies in Illinois from 12 to 35and averages 23. The obvions advantage of a true panel system is thateach panel is surrounded on all sides by a pillar of solid coaland is a separate unit in operation. A squeeze occurring inany panel is confined by the barrier pillars, if large enough.The ventilating current can be regulated so as to supply airaccording to the needs of each panel and pillar-drawing canbe more advantageously practiced, thus giving a higher coal-recovery. In Illinois some of the newer mines were opened on thepanel system and some of the older mines which had beenunsuccessful in preventing squeezes under the unmodifiedroom-and-pillar system have changed their system to panel.There are, however, only a few mines operating on a truepanel system with proper barrier pillars. In many mines nopanel is maintained but rooms are driven to hole through,the main barrier pillar is gouged, and the cross barrie

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