Mineral Facts and Problems: 1960 Edition Page: 83
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ASBESTOS
The Naval Research Laboratory conducted
experimental work on the possible use of a
paper-maker's Vortrap to remove iron minerals
from Canadian chrysotile. The Bureau of
Mines conducted similar experimental work
with its own equipment. The tests made indi-
cated that the magnetic iron content of ordinary
Quebec asbestos can be reduced to satisfy the
requirements of 2 percent or less stipulated in
the national stockpile specification for nonfer-
rous chrysotile.
The Naval Research Laboratory has devel-
oped a fiberglass gas mask filter said to be
superior to those made of Bolivian blue asbes-
tos. Bolivian crocidolite is, therefore, no longer
regarded as essential.
Considerable work has been done on the syn-
thesis of asbestos, but limited progress has been
made. The Bureau has synthesized amphibole
asbestos, but the fibers made are weak and
brittle. The Bureau also has synthesized as-bestiform compounds not found in nature that
have some of the properties of asbestos. Chrys-
otile, the type of asbestos most in demand, is
difficult to synthesize. Fibers of submicro-
scopic length only have been made (5, 9, 13,14).
Experimentation on materials that may be
substituted for asbestos indicate that fiberglass
can be used in place of asbestos for some types
of heat-insulating products. Cloth of good
quality is made using alternate strands of fiber-
glass and asbestos yarn. Such substitution
extends the supply of spinning-grade asbestos.
Fiberglass cannot be used successfully in fric-
tion materials such as brake band linings, nor in
some of the highly specialized electrical insula-
tion uses. Recent advances in the manufacture
of glass fibers offer opportunities for wider sub-
stitution. Organic plastics and silicone prod-
ucts are other materials that have limited
substitute applications.OUTLOOK
The trend in asbestos consumption follows
industrial production and building construc-
tion. In consonance with the current upward
trend in these activities, asbestos consumption
will probably increase. The overall demand in
the United States for all types and grades of
asbestos over a short-term as well as long-term
period will probably increase moderately in the
absence of a industrial recession. It may exceed
1 million tons a year within a 10-year period.
Domestic production probably will increase
gradually, but is unlikely to exceed 60,000 tons
a year from current sources over a 10-year
period. Accordingly, not more than 6 or 7 per-
cent of requirements are expected from do-
mestic sources.
Imports from Quebec will probably increase
beyond their present high levels in view of
the growing productin capacity in that Prov-
ince. British Columbia and Ontario have
become important supplementary sources.
Chrysotile supplies will apparently be adequate
for both short-term and long-term require-
ments. Production facilities are increasing for
all types of African asbestos, and larger sup-
plies will become available for importation year
byyear.
Supplementing a discussion of the overall
situation, it is desirable to consider conditions
surrounding the special types of asbestos that
are important to the economy of the United
States.
Requirements for low-iron chrysotile of spin-
ning grade suitable for electric insulation have
declined greatly during recent years. This is
due in part to a decline in new naval construc-tion, and partly to a wider use of substitute
materials in electric-cable construction and for
other nonferrous uses. It is probable that low-
iron requirements in the United States approxi-
mate 5,000 tons a year. Arizona production,
at least through 1960, will be a small factor in
industrial supply. Production for commercial
use may attain increasing importance, but there
is little prospect of a substantial growth in out-
put beyond its 1958 level until new markets
are developed. It would appear that not only
will adequate supplies of low-iron fiber from
British Columbia be imported, but a surplus
will be available for general-purpose uses.
Short-term requirements of Canadian and
similar high-iron spinning fibers are estimated
at about 20,000 tons annually, and for the long-
term period at about 25,000 tons a year. Ex-
cept for the small output in Vermont and small
quantities received from Africa and other over-
seas sources, the entire supply of high-iron
chrysotile of spinning grade originates in
Canada. It has been estimated that the Quebec
mills are capable of producing 54,000 tons annu-
ally of the spinning grades. As about 60 per-
cent of the supply is normally exported to the
United States it appears that approximately
32,000 tons annually would be available to U.S.
consumers if the Quebec mills were operating
at capacity. It is evident, therefore, that
Canada can supply all prospective short-term
or long-term needs of the United States.
U.S. requirements for amosite have been
increasing moderately. Because of its advan-
tages over chrysotile in making 85-percent-
magnesia and other light-weight insulating83
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United States. Bureau of Mines. Mineral Facts and Problems: 1960 Edition, report, 1960; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc38790/m1/91/?rotate=270: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.