United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-86/019 July 1986
&EFW Project Summary
Assessment of Solid Waste
Characteristics and Control
Technology for Oil Shale
Retorting
Ashok K. Agarwal
This work is a comprehensive study of
the characteristics of solid and liquid
wastes produced from various oil shale
processing technologies, and control
methods for environmentally safe dis-
posal of solid wastes. It also includes
results from an experimental study to
construct liners and covers for proper
disposal of spent shales. In addition the
autoignition potential of raw and spent
shales has been evaluated.
Oil shale deposits in the eastern and
western parts of the U.S., their geo-
logical subdivisions, locations, tonnage,
and physical and chemical characteris-
tics have been described. The solid and
liquid wastes generated from the vari-
ous oil shale technologies have been
compiled. Amounts of solid and liquid
wastes generated and their composition
depend, among other things, on the
technology used and on the type of
shale processed. Some of the wastes
may also be site specific. Available field
and laboratory leachate data are also
presented.
If only 50% of the planned production
comes on line, it would eventually
amount to about 600,000 barrels/day
(BPD)* of shale oil. This would lead to
about 740,000 tons/day (TPD) or 270
million tons/year of retorted oil shale,
along with lesser quantities of other
solid wastes, which would require envi-
ronmentally safe disposal. If not proper-
ly managed, these high volume wastes
•Readers more familiar with the metric system may
use the conversion factors at the back of this
Summary
are capable of producing leachates that
could contaminate the water supply for
millions of people. Surface disposal
sites covering many square miles in area
and hundreds of feet in depth would do
extensive property damage and threaten
lives should they ever suffer sudden
mass failure. An experimental program
was undertaken to establish the best
combination of spent shale with mate-
rials readily available at the disposal site
to construct liners and covers for the
spent shale disposal.
Also in this report available informa-
tion has been compiled to evaluate the
autoignition potential of raw and spent
shales from various oil shale processes.
The results indicate that raw shale fines
have a potential for spontaneous igni-
tion similar to bituminous coals, while
such potential for retorted shales ap-
pears to be less. Hence, there is a
potential that, if oil shale disposal sites
are not properly designed, they could
autoignite. It appears probable that
control technology employed by the
coal industry can be modified and
applied to oil shale disposal sites to
mitigate this hazard.
Control technologies to prevent seri-
ous adverse impacts from disposal of
billions of tons of oil shale wastes have
been proposed, but their application to
oil shale waste materials on the scale
required for commercial plants has not
been demonstrated. Furthermore, to be
effective, these control technologies
must be applied to highly technical and
integrated disposal designs that are site
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and process specific. There is no current
experience in disposal of wastes of
similar composition or of volumes ap-
proaching that which will result from
the oil shale industry.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Triangle
Park, NC. to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering in-
formation at back).
Introduction
1985 marks the start of the commercial
U.S. oil shale industry with the first
commercial plant (Union Oil's 10,000
BPD Long Ridge facility) coming on line.
Many additional and often much larger
plants are scheduled to start production
between 1987 and 1994, with many of
the early plants being subsidized by the
Federal Government through the U.S.
Synthetic Fuels Corporation. If only 50%
of the planned production comes on line,
then about 740,000 TPD or 270 million
TRY of retorted oil shale, along with lesser
quantities of other solid wastes, will
require environmentally safe disposal.
The types and quantities of solid waste
that will be produced from proposed oil
shale facilities are not yet well defined.
Although these projects are quite dif-
ferent in that they employ different retort-
ing technologies, retort different grades
of shale at different rates, produce differ-
ing amounts and types of final products
and, at times, employ differing control
technologies, the rates of solid wastes
can be compared when examined on a
common basis. The common bases used
are mined shale (tons of wastes per
thousand tons of mined shale, T/MT) and
hydrotreated oil (tons of waste per million
barrels of oil, T/106bbl).
Factors were determined on the basis
of shale mined and oil produced for 16
solid wastes. Using these factors, it is
possible to calculate probable rates of
various solid wastes produced based on
projected mining rates and product oil
production for the above-ground oil shale
retorting facilities.
Characteristics of U.S. Oil Shale
The location, geology, composition, and
physicochemical properties of oil shale
resources in the U.S. have been described.
These oil shale deposits occur in four
general locations: (a)theTertiary(Eocene)
deposits of the Green River formation in
Colorado, Utah, and Wyoming; (b)the late
Devonian and early Mississippian period
marine shales of the central and eastern
U.S., stretching from Michigan and
Pennsylvania south through Indiana and
Kentucky, to Texas; (c) the early Creta-
ceous and upper Triassic marine shales
in Alaska; and (d) the small Tertiary shale
deposits of Montana, Nevada, Idaho, and
California.
Not all of these deposits are sufficiently
rich in organic matter to be considered
commercially attractive. Estimates place
total known U.S. oil shale resources for
oil shales yielding 1 0 gal. of oil per ton of
shale at well over 2 x 10'2 bbl. The Green
River formation oil shales in Colorado,
Utah, and Wyoming account for an esti-
mated 90% of this total resource and are
therefore regarded as being the most
important commercially.
Solid Wastes and Their
Characteristics for Oil Shale
Retorting Processes
Solid wastes, amounts generated, and
their characteristics for various oil shale
retorting processes were studied. The
following oil shale retorting processes
were considered: Lurgi-Ruhrgas, TOSCO
II, Paraho direct heating mode, Paraho
indirect heating mode. Occidental modi-
fied in situ, T3 retorting, Hytort, Geo-
kinetics horizontal in situ, Superior cir-
cular grate, Union Oil A, Union Oil B,
Union Oil SGR, Chevron STB, Allis
Chalmers, and Dravo. The available in-
formation on solid wastes for these
retorting technologies was gathered, and
the best available information for each
technology is presented in the main
report. The extent of data availability
varies substantially from process to pro-
cess. The composition of solid wastes and
their physicochemical properties, along
with leachate data, are presented in a
systematic format.
Potential Dangers to Human
Health and the Environment
from the Disposal and
Reuse of the Wastes
Although oil shale facilities will produce
huge volumes of solid wastes, the poten-
tial for reuse of the wastes is small. Some
wastes such as spent catalysts could
potentially be reclaimed and recycled
back into the process. Elemental sulfur,
removed by some air pollution control
technologies, has a limited market poten-
tial; however, it remains to be demon-
strated on a commercial scale that there
are no trace impurities that would con-
strain its use. It is expected that hazardous
wastes such as spent catalysts and some
sludges will be disposed of in licensed ,
hazardous waste facilities. However, one
catalyst (unique to shale oil upgrading) is
of particular concern: the arsenic guard
bed catalyst, which contains 20% or more
arsenic. No facilities exist to reprocess
this spent catalyst, and environmentally
safe disposal may be difficult to achieve.
Other than the arsenic guard bed catalyst,
the major unique dangers to health or the
environment posed by oil shale facilities
may be from the long term effects of on
site disposal of millions of tons of retorted
oil shale, raw oil shale waste, and other
process wastes. Principal concerns in
this regard may be summarized as:
1. Autooxidation/autoignition may be a
serious problem if raw shale fines
and/or carbonaceous spent shales
are not disposed of in a manner to
minimize this risk.
2. High inorganic salt loading and pos-
sibly organics in leachates from raw
shale fines or spent shale could
potentially have significant impacts
on groundwater supplies in the area
and on surface waters that supply
millions of people (Colorado River). A
related issue is the extent to which
process wastewaters should be
treated prior to codisposal with the
retorted shale. Codisposal of spent
catalysts and treatment sludges may
also significantly impact the nature
of leachates from disposal sites.
3. Infiltration of moisture into disposal
sites from precipitation or from sur-
face or groundwater intrusion could
lead to sudden pile failure. Such
failure could cause extensive property
damage, threaten lives, and contam-
inate the drinking water supply for
millions of people.
Present/ Proposed
Disposal Practices
The slate of solid wastes to be disposed
and their chemical nature will vary in
response to the nature of the raw shale
feed, the retorting process employed, the
plant design (including pollution control
technologies), and whether raw shale oil
is upgraded on site. The design of the
solid waste disposal site as well as the
selection and application of appropriate
control technologies must be tailored to
accommodate not only the quantities and
nature of the wastes but also the char-
acteristics of the disposal site. Alternative
disposal practices and control technol-
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ogies are generally well known. All have
been proposed or considered by one
developer or another though no developer
has yet proposed a plan incorporating all
the control features that might be desired
into a design for solid waste disposal.
Key features for handling solid wastes
produced by a surface retorting process
are presented in the full report, with a
discussion of the control technologies
applicable to the disposal alternatives.
Use of Spent OH Shale as a
Liner Material at Spent Shale
Disposal Sites
This study has considered the possibil-
ity of using a spent oil shale itself as a
water barrier or "liner" beneath a spent
oil shale waste embankment. Pertinent
properties of unburned TOSCO II spent
shale and an average mixture of Lurgi
spent shale have been measured. Mate-
rials consisting of 10, 20, and 30% burned
spent TOSCO shale admixed into un-
burned TOSCO II shale have also been
considered. Two autoclave mellowed
materials admixed into their respective
unmellowed spent shales have also been
studied.
This work indicated the difficulty of
having both easy self-healing and low
permeability of the unmellowed TOSCO
materials and mixtures and perhaps also
of the unmellowed Lurgi spent shale.
Autoclave mellowing of the burned
TOSCO material, however, produced a
high plasticity index material that may be
blended with the silty unburned TOSCO II
spent shale to produce a liner having (at
least in the short term) both low perme-
ability and good self-healing possibilities.
A similar attempt with the Lurgi spent
shale was not successful due to the high
permeability produced in the short term
aging experiments.
impacts of Disposal
Alternatives on the
Use of Oil Shale and
Other Natural Resources
Due to the volume of solid wastes
produced by an oil shale facility, these
wastes must be disposed of on or near the
plant site. In the case of open pit mines,
huge amounts of overburden and sub-
grade oil shale will also require disposal.
These wastes could be disposed of entire-
ly on the surface as piles or canyon fills or
could partially be returned to the mine.
Either way the leaching potential of these
wastes must be carefully controlled or
leachates will seriously impair the quality
and use of surface and groundwater
supplies. Depending on the placement of
these wastes they could also impair
future access to other oil shale resources.
Returning some of the retorted oil shale
to an underground mine would be expen-
sive and technically difficult but could
actually increase the potential for re-
source recovery by facilitating mining of
the support pillars.
Potential Utilization of Oil
Shale Solid Waste
Oil shale solid wastes having some
potential for utilization include retorted
oil shale, raw shale fines, spent catalysts,
elemental sulfur, and biological treatment
sludges. Retorted oil shales, particularly
decarbonized shales, have some limited
potential for utilization on site. Decar-
bonized western oil shales possess a
significant capacity to cement similar to
low grade commercial cement. Hence a
very limited amount of retorted shale may
be used locally as a low grade cement
substitute. Raw shale rejects and fines,
from mining and raw shale preparation,
could be processed in specially designed
retorts or possibly formed into briquettes
and processed in the regular plant facil-
ities. Spent catalysts could potentially be
reclaimed and reused in the upgrading
process, though facilities to reclaim them
do not presently exist. Some air pollution
control technologies remove elemental
sulfur which, if not contaminated by
impurities, should have at least a limited
market for agricultural use. Biological
treatment sludges may be useful on site
as soil conditioners for revegetation if
they do not contain significant quantities
of harmful contaminants. However, even
if all the above wastes are utilized to the
maximum extent possible, it will not make
a significant impact on the amount of
solid waste to be disposed of.
Conclusions
1. The oil shale industry will produce
unprecedented volumes of solid
waste consisting mostly of retorted
oil shales, raw oil shale fines, over-
burden and subgrade ore, codisposed
wastewater, and much smaller quan-
tities of known hazardous wastes.
Although the known hazardous
wastes will be sent to licensed dis-
posal or recycling facilities, the high
volume solid wastes will be disposed
of on or near the plant site. If not
properly managed these high volume
wastes are capable of producing
leachates that could contaminate the
water supply for millions of people.
Some of the waste may also pose the
hazard of autoignition unless proper
controls are employed. Surface dis-
posal sites covering square miles in
area and hundreds of feet in thick-
ness would do extensive property
damage and threaten lives should
they ever suffer sudden mass failure.
2. Control technologies to prevent seri-
ous adverse impacts from disposal of
billions of tons of oil shale wastes
have been proposed, but their appli-
cation to oil shale waste materials
and on the scale required has not
been demonstrated. Further, to be
effective, these technologies must be
applied in highly technical and inte-
grated disposal designs that are site
and process specific. There is no
current experience in disposal of
wastes of similar composition or of
volumes approaching that which will
result from the oil shale industry.
Metric Conversions
Although EPA's policy is to use metric
units in all its documents, certain non-
metric units have been used in this
Summary for the reader's convenience.
Readers more familiar with the metric
system may use the following conversion
factors.
Nonmetric Times Yields Metric
bbl
°F
ft
ft3
in.
mi2
psi
ton
158.98
5/9(°F-32)
0.3048
28.316
2.54
2.59
70.307
0.9072
L
°C
m
L
cm
km2
g/cm2
tonne
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Ashok K. Agarwal is with Monsanto Co., Dayton, OH 45418.
Edward R. Bates is the EPA Project Officer (see below}.
The complete report, entitled "Assessment of Solid Waste Characteristics and
Control Technology for Oil Shale Retorting." fOrder No. PB 86-198 371/AS;
Cost: $28.95, subject to change} will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S7-86/019
0000329 PS
U S ENVIR PROTECTION AGENCY
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