Uranium content and leachable fraction of fluorspars.
Much attention in the radiological health community has recently focused on the management and regulation of naturally occurring radioactive materials. Although uranium-bearing minerals are present in a variety of fluorspar deposits, their potential consideration as naturally occurring radioactive materials has received only limited recognition. The uranium content of 28 samples of acid- and cryolite-grade (>97% CaF2) fluorspar from the National Defense Stockpile was found to range from 120 to 24,200 microg kg(-1), with a mean of 2,145 microg kg(-1). As a point of comparison, the average concentration of uranium in the upper crust of the earth is about 2,500 microg kg(-1). Leachability of this uranium was assessed by means of the Toxicity Characteristic Leaching Procedure (TCLP). The TCLP extractable fraction ranged from 1 to 98%, with a mean of 24% of the total uranium. The typically low concentrations of uranium seen in these materials probably reflects the removal of uranium-bearing mineral phases during the beneficiation of the crude fluorspar ore to achieve industrial specifications. Future NORM studies should examine crude fluorspar ores and flotation tailings.
Landa
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US Geological Survey, Reston, VA 20192, USA. erlanda@usgs.gov
Councell
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D006801:Humans; D008903:Minerals / Q000032:analysis; D008906:Mining; D011850:Radioactive Waste; D012990:Soil Pollutants, Radioactive / Q000032:analysis*; D014481:United States; D014501:Uranium / Q000032:analysis*
D008903:Minerals; D011850:Radioactive Waste; D012990:Soil Pollutants, Radioactive; D014501:Uranium