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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hod of mining. The waste should fill thegob sufficiently to allow the roof to come down graduallywithout breaking off short at the face of the pack walls, butshould not fill the gob so completely that it carries too muchof the roof and does not throw enough weight on the face ofthe coal. The better the gob is packed, the better the coalworks. The width of the pack wall, called building, neces-sary to prevent the walls from squeezing out and filling the MINING PRACTICE 103 roadway when the roof weight comes on them depends nponlocal conditions. The Third Vein District Agreement be-tween the Illinois Coal Operators Association and the UnitedMine Workers of America in Article 1 provides: Theminer shall build 4 yards of wall at each side of his road, andif he has more rock than is required therefor he shall notload any of it until he has filled his place therewith. In casethe miner has not rock enough to build his 4 yards he shall,at the request of the company, begin his wall 4 yards from
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Fig. 26. Chute in panel longwall mine in dipping seam (photo1 by H. I. Smith,U. S. Bureau of Mines) ■ the roadside; provided, that the above shall not prohibitthe miner, at his option, from beginning his wall at any great-er distance upon the request of the company. When somepart of the face has been allowed to lag behind and the work-ing face has squeezed, the area is not usually cleaned up, butthe face is diverted to pass around the squeezed area, some-times leaving a small block of coal in the gob. The effect of the subsidence of the roof upon the over-lying strata and upon the surface after the coal has been 104 COAL MINING INVESTIGATIONS removed has not been clearly determined. Surface subsi-dence has been the subject of extended litigation. While itis undoubtedly true that there is subsidence of the strata im-mediately overlying the coal, opinion is divided as to the ex-tent of this subsidence. There are not sufficient data avail-able from which to formulate a general rule for
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