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COAL
associated techno-economic studies. British
Coal has undertaken an extensive study compar
ing
several IGCC and partial gasification
combined-cycle systems based on a number of
gasification technologies and utilizing various
biomass/sewage sludge/coal co-firing ratios.
Future Research Prospects
The European Commission has drafted the basis
for the Fourth Framework Program. In effect, this
is the next 5-year plan covering a wide range of
issues including coal utilization research, develop
ment and demonstration. This program, which is
likely to commence in 1996, aims to build on the
ongoing initiatives. Thus there will be more op
portunities to study
co-utilization of coal with
either biomass or waste. In particular, there will
be an examination of the use of advanced coal
technologies for enhanced disposal of chemical
wastes and associated toxic compounds.
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FOSSIL RESIN IS A POTENTIAL
VALUE-ADDED PRODUCT FROM WESTERN
U.S. COALS
The University of Utah has established a
Coal/Fossil Resin Surface Chemistry Laboratory
to study the fossil resin (resinite) found in certain
coals in the Western United States. Such
resinous coals are found, for example in the
States of Arizona, Colorado, New Mexico, Utah,
Washington, and Wyoming. Among these, the
Wasatch Plateau coal field in central Utah is of
great value because of its particularly
high con
tent of macroscopic fossil resin. Many seams in
this coal field have been reported to contain as
much as 5 percent resin by weight. Fossil resin
liberated from other coal
is friable and easily
macerals. Consequently, the resin particles tend
to concentrate into the fine sizes during coal
preparation and handling. Because of this
property, it is not unusual to find that the minus
28-mesh coal streams in a coal preparation plant
contain more than 10 percent hexane-soluble
4-28
resin, even when the run-of-mine coal contains
only 3 percent resin.
Research on the fossil resin has been described
by
J. Miller et al. in papers published in Enerpeia
and at the 11th Annual Pittsburgh Coal Con
ference.
According to Miller et al. fossil resin from Utah
coal generally exhibits low density, a range of
colors, and good solubility in hexane and/or hep
tane. It has been recovered intermittently from
the Utah coal field since 1929 by gravity and/or
flotation processes. The production, neverthe
less, has been on a very small scale and the tech
nologies used have limited the development of a
viable fossil resin industry. Of the four coal
preparation plants in the Wasatch Plateau coal
field (King, Plateau, Beaver Creek, and Price
River), resin has been recovered only intermit
tently from the U.S. Fuel plant, where a small
amount of this valuable resource was separated
by flotation (50 percent recovery from the fines)
as an impure concentrate containing about
50 percent resin. However, operations at the
U.S. Fuel plant have been terminated. The resin
flotation concentrates thus produced are refined
by
solvent extraction. Solvent-purified resins
from the Wasatch Plateau coal field typically have
a molecular weight of about 1 ,200 and a soften
ing point of about 170C.
This product, at the present time, has a market
value of at least $1 .00 per kilogram as a chemical
commodity and can be used in the adhesives,
rubber, varnish, paints, coatings, and thermoplas
tics industries, and particularly in the ink industry.
Selective flotation of resin from coal is difficult
with conventional flotation reagents and a multi
stage flotation process is usually required to
produce a resin concentrate of modest quality.
Unfortunately, process technology for the
recovery
and utilization of fossil resins from coal
has not received much attention. Because of the
lack of technology and the competition from syn
thetic resins, the valuable fossil resin resource
THE SYNTHETIC FUELS REPORT, JANUARY 1995