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Bureau of Mines / Minerals yearbook: Metals and minerals 1977
Year 1977, Volume 1 (1977)

Cooper, Franklin D.
Mining and quarrying trends in the metal and nonmetal industries,   pp. 37-60 PDF (2.0 MB)


Page 37

Mining and Quarrying Trends in the Metal and Nonmetal 
Industries 
By Franklin D. Cooper' 
 The value of nonfuel raw mineral production in the United States for 1977
increased over that of 1976 by 5%, from $16.7 billion to $17.5 billion. Metals
declined by 5% from $6.1 billion to $5.8 billion, chiefly because of strikes
in the iron ore industry and a depressed copper market. Subsidization of
mining industries in some foreign countries accounted in part for the excess
of copper and some other metals on world markets. Weak metal markets and
continued slowdowns in the world economy were the main reasons of the virtual
absence of new mine projects. 
 Increasing domestic governmental involvement affecting mineral industry
activities, such as pricing controls, public land withdrawals, and the Surface
Mirung Control and Reclamation Act, effective August 3, continued to be controversial
and to be criticized by various segments of the industry. 
 Large capital outlay and the long lead time to attain production from a
new facility were also of concern. Because of increasing costs and depletion
of higher-grade reserves, the mining industry relied heavily on technology
to develop more efficient mining and processing methods. 
 The use of raise- and shaft-boring was popular, compared with former development
practices, because less completion time was required. Mine ventilation was
improved and less maintenance was needed after the boring was completed.
Four U.S. companies produced raise-boring machines, one of which could produce
a 350,000-footpound torque and a 2-mfflion-pound thrust. One manufacturer
patented a "taper-lock" removable stem to eliminate the replace
ment of entire boring heads up to 20 feet in diameter when only the stem
is broken. 
 Although pneumatic drill rigs dominated in most underground mines, hydraulic
percussion drills with one single moving part gained favor because of faster
penetration and less noise while requiring less energy and maintenance. 
 A twin-boom tunneling jumbo equipped with a dry dust collector met the strict
requirements of environmental inspectors in an underground limestone mine.
 The Bureau's continuous spiral drill-andblast concept, when tested in the
White Pine Copper mine, indicated advance rates four times that of conventional
drill-andblast methods. 
 Explosives manufacturers introduced a new plastic connector, the Safe-T-Tube,
to prevent premature detonation of detonating cord. Two new explosives were
made available for underground blasting. 
 Diesel-powered haulage continued to increase in noncoal underground mines.
 A roof-support system using 14- to 18-footlong fiberglass beams permitted
a continuous mining operation, as demonstrated in a Pennsylvania mine, to
advance 20 feet farther than with steel beams previously used. The Bureau
of Mines developed an improved method for anchoring roof bolts, using a cartridge
containing quick-setting portland-gypsum cement and microencapsulated water.
 Tungsten-halogen lighting was initially introduced in underground mines
as were two new designs of roof bolts. 
 In the surface mining sector, trends in new equipment were diversified.
A 16-cubicyard hydraulic-type shovel was being tested 
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