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U.S. Department of Energy
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Direct utilization - recovery of minerals from coal fly ash. Fossil Energy Program. Technical progress report, 1 April 1984-30 June 1984

Technical Report ·
OSTI ID:6466353

Research progress is reported on two methods for extracting metal values from power plant fly ash. In the first method (the HiChlor process), a carbochlorination reaction is used to produce a mixture of volatile metal chlorides from the oxides in the ash. Developmental research is underway on a unique slurry reactor in which the ash is contacted by gaseous chlorine while suspended with finely divided carbon in a molten salt (NaCl + AlCl/sub 3/). Experimental apparatus is being tested and the necessary analytical procedures are being developed. In the second method, a lime-sinter solid state reaction is used to selectively convert the alumina in the ash to a soluble form. The alumina is recovered by leaching the finely divided clinker. This report deals with the effects of mineralizers on the sinter reaction as a means for increasing alumina yield and reducing the required temperature. Dissolved silica in the alumina-containing extract from the leaching of the lime-sinter clinker can result in an alumina product that fails to meet electrolytic cell feed specifications. Research has shown that the silica content can be reduced by digestion with a small amount of lime. The amount of lime addition, digestion temperatures required, and desilication reactions occurring are reported. New data are also presented on the recovery and purification of the alumina product. Preliminary research on the production of low-alumina, sulfate resistant cement from the extracted sinter residue has resulted in information on the need for such cement, estimated costs, and experimental work required. 5 references, 4 figures, 3 tables.

Research Organization:
Ames Lab., IA (USA)
DOE Contract Number:
W-7405-ENG-82
OSTI ID:
6466353
Report Number(s):
IS-4864; ON: DE85002672
Country of Publication:
United States
Language:
English