Radium in uranium mill tailings - Some observations on retention and removal

Scientific Basis for Risk Assessment and Management of Uranium Mill Tailings

“…Stieff's work, using nuclear emulsion techniques, indicates that these radium-alkaline earth coprecipitates are difficult to dissolve but are fine enough (the radiocolloids are too small to resolve at 1000 times magnification) to remain suspended once they become windborne until they are redeposited by turbulent fluctuations or washed out by rain. Radium is also, to some degree, adsorbed on silica particles, on metal hydroxides, on clays, and in the pores of larger solid particles (Nirdosh et al, 1984). Studies by Landa (1980Landa ( , 1982b and generally support these findings.…”

“…Landa (1980, 198213) and Nirdosh et al (1984) have inferred, on the basis of chemical investigations, that radium in the tailings is present primarily as sulfate coprecipitates, e.g., bariumradium sulfates and jarosite-SEM (scanning electron microscope) studies are desirable to validate this inference. Seeley (1977) and Ryon et al (1977), among others, have suggested that coprecipitates with other alkaline earths, such as calcium and strontium, may also be important.…”

“…Most of the radium is associated with the slime fraction in the tailings (Nirdosh et al, 1984); hence, it may only be necessary to treat the slimes provided that the sands have acceptably low radium content.…”

“…While small-scale experiments by Nirdosh et al (1984Nirdosh et al ( , 1985 have demonstrated the feasibility of the process, pilot-scale studies would be required before implementation. Cost factors, particularly with regard to EDTA consumption, would also have to be evaluated carefully.…”

Leaching of uranium and 226ra from low‐level radioactive waste from port hope, ontario

“…However, they had found that a portion of radium behaved as an "unextractable fraction" and could not be leached even at infinite liquidisolid ratio. Nirdosh et al (1984) found that the "unextractable fraction" was in fact the quantity of radium either adsorbed on silica or adsorbed and bound in hydroxide matrices of hydrated oxides of metals and < 1. Thus, by reducing Fe3+ to Fe2+, the iron hydroxide is dissolved in EDTA and so is radium associated with it.…”