Impact of oxidation and reduction on the leaching potential of trace metals from spent oil shale. [Reducing and oxidizing environment]

Technical Report · Sun Dec 01 04:00:00 EST 1985

OSTI ID:6985012

Sullivan, P J; Carroll, R B

The long-term quality of water produced at spent oil shale disposal facilities is a critical concern. Understanding the release and mobility of trace elements as natural weathering of the disposal pile occurs is particularly important. Because spent oil shale leachates are highly alkaline, weathering reactions that increase leachate acidity, thus trace element release and mobility, must be characterized. In order to simulate weathering environments that would occur in a waste disposal pile (i.e., saturated and unsaturated groundwater environments), spent oil shale has been leached under saturated and unsaturated conditions. Unsaturated conditions (an oxidizing environment) allow the oxidation of iron sulfides and adsorption of carbon dioxide. Saturated leaching conditions (a reducing environment) should not allow the acid generation by oxidation or carbon dioxide adsorption. Both of these conditions generate hydrogen ions and should reduce pH in spent oil shale leachate. Spent oil shale was leached for six weeks and the leachate analyzed for pH, sulfates, arsenic, boron, cadimum, calcium, copper, lithium, magnesium, manganese, sodium, strontium, and zinc. The leaching studies indicate that the oxidizing simulation did not significantly decrease the leachate pH, and under reducing conditions the greatest concentration of trace elements were leached from the shale. The trace elements extracted from the spent oil shale in the greatest concentrations are all soluble in high pH solutions. These results indicate that spent oil shale disposal piles in arid to semiarid environments may maintain an alkaline pH because of an extremely high alkaline buffering capacity. These data also indicate that research on carbon dioxide absorption is needed to assess the long-term contribution of acidity to modify solution pH and trace element mobility. 15 refs., 2 tabs.

• Research Organization: Western Research Inst., Laramie, WY (USA)
• DOE Contract Number: FC21-83FE60177
• OSTI ID: 6985012
• Report Number(s): DOE/FE/60177-2303; ON: DE87008056
• Country of Publication: United States
• Language: English

Related Subjects

04 OIL SHALES AND TAR SANDS
040900* -- Oil Shales & Tar Sands-- Waste management
ALKALI METALS
ALKALINE EARTH METALS
ARSENIC
BORON
CADMIUM
CALCIUM
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
COPPER
DATA
DISPERSIONS
DISSOLUTION
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
LEACHATES
LEACHING
LITHIUM
MAGNESIUM
MANAGEMENT
MANGANESE
METALS
MIXTURES
NUMERICAL DATA
OXIDATION
OXYGEN COMPOUNDS
PH VALUE
REDUCTION
SEMIMETALS
SEPARATION PROCESSES
SODIUM
SOLUTIONS
SPENT SHALES
STRONTIUM
SULFATES
SULFUR COMPOUNDS
TRANSITION ELEMENTS
WASTE DISPOSAL
WASTE MANAGEMENT
WEATHERING
ZINC