How to determine yield load of longwall roof supports
Ever since the installation of the first powered supports in the US during the late sixties, longwall production has been increasing. The latest statistics show that longwall mining accounted for about 19.7% of the total US underground coal production in 1984/sup 1/. In 1985 and 1986 longwall equipment purchases reached a peak. There were 22 new faces in 1985/sup 1,2/. Preliminary data show that a similar purchase will occur in 1986 (Fig. 1). Following the improvement of production, the yield load of the shields continues to increase. As shown in Fig. 2, the shields installed in 1985 had an average yield load of 569.1 tons/unit, an increase of 61.6% over 1975. Since 1982 five mines have installed shields with yield load larger than 760 tons/unit, and since 1984 no shields with yield load less than 500 tons/unit have been ordered. Since shield weight and price depend largely on yield load, it is important to know how to determine the yield load for US mining conditions. Various researchers have proposed many methods to determine yield load, but these methods can seldom be practically applied to specific mines. Therefore, most engineers rely mainly on experience and on some simple but inaccurate rules of thumb. England and West Germany have each established a minimum standard for support load density. However, field investigations show that their standards are not suitable for US conditions.
- Research Organization:
- West Virginia Univ., Dept. of Mining Engineering, College of Mineral and Energy Resources, Morgantown, WV
- OSTI ID:
- 7015557
- Journal Information:
- Coal Min. Process.; (United States), Vol. 23:10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
42 ENGINEERING
LONGWALL MINING
SHIELD SUPPORTS
COST
LOADING
STANDARDS
STATIC LOADS
USA
COAL MINES
CALCULATION METHODS
FEDERAL REPUBLIC OF GERMANY
INSTALLATION
PRICES
PRODUCTION
RESEARCH PROGRAMS
UNITED KINGDOM
WEIGHT
WORKING FACES
EUROPE
MATERIALS HANDLING
MECHANICAL STRUCTURES
MINES
MINING
NORTH AMERICA
POWERED SUPPORTS
SUPPORTS
UNDERGROUND FACILITIES
UNDERGROUND MINING
WESTERN EUROPE
012030* - Coal
Lignite
& Peat- Underground Mining- (1987-)
420206 - Engineering- Mining & Drilling Equipment & Facilities- (1980-1989)