Mill tailings

Mill tailings are another form of nuclear waste. The residue from uranium ore extraction contains radium, the precursor of short-Hved radon and its daughters. Piles of tailings must be properly covered. 

Mill Tailings. Recovery efficiency in ore processing is not 100%. Accumulated mill tailings contain tens of thousands of metric tons of uranium. Whereas improved techniques have been employed to recover some of this uranium, the recovery rate is still generally low, approximately 35—50%, owing to metallurgical problems and economic considerations (33). 

Classification of wastes may be according to purpose, distinguishing between defense waste related to military appHcations, and commercial waste related to civiUan appHcations. Classification may also be by the type of waste, ie, mill tailings, high level radioactive waste (HLW), spent fuel, low level radioactive waste (LLW), or transuranic waste (TRU). Alternatively, the radionucHdes and the degree of radioactivity can define the waste. Surveys of nuclear waste management (1,2) and more technical information (3—5) are available. 

Most uranium ore has a low, ca 1 part in 500, uranium content. Milling involves physical and chemical processing of the ore to extract the uranium. The mill tailings, which release gaseous radon-222 [13967-62-9] Ra, half-life 3.82 d, are placed in large piles and covered to prevent a local health problem. 

Blast furnace slag, concentrates, ore mill tailings, plating sludge... 

Control layers, such as those used to minimize animal intrusion, promote drainage, and control and collect landfill gas, are often included for conventional cover systems and may also be incorporated into ET cover system designs. For example, a proposed monolithic ET cover at Sandia National Laboratories in New Mexico will have a biointrusion fence with 1/4-in. squares between the topsoil layer and the native soil layer to prevent animals from creating preferential pathways, potentially resulting in percolation. The biointrusion layer, however, will not inhibit root growth to allow for transpiration. At another site, Monticello Uranium Mill Tailings Site in Utah, a capillary barrier ET design has a 12-in. soil/rock admixture as an animal intrusion layer located 44 in. below the surface, directly above the capillary barrier layer. 

Uranium Mill Tailings Repository, UT (ACAP project) Hazardous waste landfill Operational July 2000... 

Danse IHR, Garb LG, Moore RH. 1995. Blood lead surveys of communities in proximity to lead-containing mill tailings. Am Ind Hyg Assoc 56 384-393. 

A major objective in developing these risk estimation procedures was to provide a method capable of evaluating hundreds of properties in several communities within the DOE Uranium Mill Tailings Remedial Action Program in a timely manner. Therefore, we chose a calculation scheme that could be performed using commercially available database software (dBASE II, a trademark of Ashton-Tate, Culver City, CA), but that at the same time would be flexible enough that assessments for other contaminants could be readily incorporated. 

We have previously documented the methodology (Marks et al., 1985a) and presented a summary of the technique (Marks et al., 1985b) at the Maastricht, The Netherlands, Seminar on Exposure to Enhanced Natural Radiation and Its Regulatory Implications. This paper represents a synthesis of the work we have conducted to date on risk assessment at uranium mill tailings vicinity properties. 

Table II Range of Observed Radiation Levels and Radionuclide Concentrations at Uranium Mill Tailings Vicinity Properties...

Environmental Protection Agency, Environmental Surveys of the Uranium Mill Tailings Pile and Surrounding Areas, Salt Lake City, Report No. EPA-520/6-74-006, U.S. Environmental Protection Agency, Las Vegas, NV (1974). 

Gustin, M.S., G.E. Taylor, Jr., and T.L. Leonard. 1995. Atmospheric mercury concentrations above mercury contaminated mill tailings in the Carson River drainage basin, NV. Water Air Soil Pollut. 80 217-220. Gutenmann, W.H., J.G. Ebel, Jr., H.T. Kuntz, K.S. Yourstone, and D.J. Lisk. 1992. Residues of /J.//-DDE and mercury in lake trout as a function of age. Arch. Environ. Contam. Toxicol. 22 452-455. 

Blowes, D.W., Ptacek, C.J., Jambor, J.L 2003. Mill Tailings Hydrology and Geochemistry. Environmental aspects of Mine Waste. Mineralogical Association of Canada Short Course series 31, 95-116. Etcheverry, D.J. 2009. Spatial and Temporal Variations in the Ruttan Mine Tailings, Leaf Rapids, Manitoba, Canada. M.Sc. thesis, University of Manitoba, Winnipeg, Manitoba. 

Donahue, R., Hendry, M.J., Landine, P. 2000. Distribution of arsenic and nickel in uranium mill tailings, Rabbit Lake, Saskatchewan, Canada. Applied Geochemistry, 15, 1097-1119. 

H. Weiss, B. Daus, J. Mattusch (1999) Arsenic mobilization and precipitation from a tin mill tailings in the Erzgebirge, Germany.- Chron. Rech. Min. 534,13 - 19... 

Keywords phytoremediation, radionuclides, 137-caesium, 90-strontium, 125-iodine, uranium, radium, uranium mill tailings, biomonitoring... 

Radium, thorium, and other radionuclides accumulate in uranium mill tailings. The potential environmental effects of these radionuclides has become of increasing concern to the public. In the future, it may be necessary to modify existing uranium recovery processes to accommodate removal of radium and perhaps other radioactive decay products of uranium. 

Sill CW. 1977. Simultaneous determination of U-238, U-234, Th-230, Ra-226, and Pb-210 in uranium ores, dusts, and mill tailings. Health Phys 33 393-404. 

Mill tailings are wastes produced when uranium ore is mined and then processed. In 2003, there were 26 sites licensed to handle mill tailings in the United States. Most of the sites were no longer processing uranium ore. In addition, another 24 sites have been abandoned. The licensed sites contain about 220 million short tons (200 million metric tons) of mill tailings and the 24 abandoned sites, about 29 million short tons (26 million metric tons) of tailings. 

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