Retorting above-ground

Above-Ground Retorting. AGR processes can be grouped into DH or IH processes. Numerous design configurations as well as a variety of heat-transport mediums have been used in the indirect heated processes (Table 7). 

The extraction of oil from mined shale by retorting is an established technology. The major above ground retorting processes have been under development intermittently for over 50 years. A variety of processes are presently candidates for full scale commercialization. 

A Fischer assay simulates the conversion of oil shale to usable fuels in an above-ground retort. The results of an extensive program of chemical analysis of major and trace elements in spent shale, oil, and water collected from the Fischer assay of a standard oil shale are presented. The concentration of major elements in raw and spent shale can be determined only to 10% in this study. Two criteria show that fluorine and zinc may have been mobilized during the assays. The concentrations of arsenic and selenium in the Fischer assay retort water exceed the maximum permissible concentrations for drinking water. 

In summary, it appears that oil-shale retorting is a reasonably clean process with regard to trace element loss from above-ground retorts. Careful control of the fate of the process water should be established. Possible releases will depend on how the trace elements are contained in the raw and spent shale and the temperature and reducing conditions under which the retort is operated. Further studies on raw and spent shale should address these questions. How the retort conditions could affect the emission of trace elements can begin to be seen in the results of the mass balance studies performed by the Berkeley group (J). 

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