Section 9. OIL AND GAS FIELD WASTES
SORPTION/DESORPTION OF VARIOUS INORGANIC AGENTS
ON OIL SHALE
Donna M. Cowher, Graduate Research Assistant
Gregory D. Boardman, Associate Professor
Adil N. Godrej, Graduate Research Assistant
Department of Civil Engineering
Virginia Polytechnic Institute and State University
Blacksburg, Virginia 24061
INTRODUCTION
Since the "energy crisis" of the early seventies, the United States has been striving to better
manage and develop the nation's natural resources of coal, gas and oil. There has also been increased
interest in producing synthetic fuels (synfuels) from coal, plants, and other materials containing hydrocarbons. Among these are oil shales, one of the largest and least used fossil fuel resources in the
United States. Operations associated with processing shales, however, may create some environmental
problems that must be considered before shale oil can be produced commercially. Two of the major
waste problems associated with the production of shale oil are the management and disposal of large
amounts of spent (or retorted) shale and wastewaters from the retorting processes.
It is envisioned that spent shales will be disposed of in an area managed and designed similar to
a common landfill. It is therefore imperative that an appreciation for the types and amounts of
materials which will elute from the shales be gained. This type of information can then be used to
evaluate the hazards associated with the land disposal of shales.
Various disposal and reuse alternatives have been suggested in an attempt to alleviate the spent
shale disposal problems. Shale might be used as an adsorbent as is activated carbon; e.g., shale might
be integrated into a treatment scheme for retort waters. Another suggestion, which is currently under
great scrutiny, is to co-dispose spent shale and process waters in a landfill-type disposal system. The
process water would serve to moisten the shale, thereby preventing dust problems, and the costs
associated with treating process wastewaters would be eliminated. However, under current Resource
Conservation and Recovery Act (RCRA) policy, co-disposal is not permitted. The major concern is
that the two separate waste problems might combine to create a more serious problem.
Aqueous solutions in most natural systems contain mixtures of many organic and inorganic agents.
In a landfill where co-disposal is practiced, shale will come into contact with many solutes, some
produced by the leaching of constituents from the shale itself and others introduced by the process
waters. Some materials might be adsorbed and/or precipitated, thereby reducing the concern for
potential contamination of surface waters or aquifers. On the other hand, solutes in process waters
might pass through the shale readily, cause elution of other substances from the shale, or interact
with shale constituents to produce even more hazardous substances. There are a number of different
scenarios for the sorption/desorption (S/D) of substances which makes it very difficult to predict
how solutes alone and in mixtures will behave. The research presented herein was undertaken to
provide some insights into the S/D behavior of various inorganic substances on four shales.
METHODS AND MATERIALS
Both batch and continuous-flow, column trials were performed in this study with four shales
obtained from the Department of Energy. The four types of shales considered were: 1) a medium
rich raw shale from Anvil Points, Colorado; 2) Oxy 6 spent shale, retorted by Occidental Oil Shale,
Inc.; 3) Antrim spent shale (an eastern shale); and 4) Run 16 spent shale (a Colorado shale), retorted
at Laramie, Wyoming.
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