Environ. Sci. Technol. 2009, 43, 3968
Comment on “Sustainability of Uranium Mining and Milling: Toward Quantifying Resources and Eco-Efficiency” Uranium mining can be a controversial public issue, and the potential for nuclear power to help mitigate climate change is now being discussed openly. The increasing availability of resources and environmental data in the public arena is assisting these considerations and allows attempts toward quantifying resources and eco-efficiency as provided by Mudd and Diesendorf (1). The Beverley Uranium Mine in South Australia is Australia’s first In Situ Recovery (ISR; also known as In Situ Leach, ISL). The Beverley uranium deposit is located in a series of isolated “bathtub” aquifers as demonstrated by pumping tests (2). Uranium is mined by drawing the naturally saline and radioactive groundwater from the Namba Formation (mining) aquifer, conditioning it with sulfuric acid and hydrogen peroxide, returning it to the orezone, and drawing it out again (3). Uranium is extracted from the groundwater, which is then conditioned again, and the process is repeated many times using the same water (typically 50-100 times). A neutral water balance is maintained in the mining aquifer, hence net consumption from this source is zero. The only net water use is sourced from the Great Artesian Basin (GAB) and is eventually lost as evaporation. Annual GAB water use and production of U3O8 for the last several years is given in Table 1. Mining areas are typically leached for 50-100 pore volumes before uranium recovery becomes uneconomic under current technology and prices. The actual normalized water consumption figures given in Table 1 are considerably more than an order of magnitude less than the 7800 ML/yr and 6300 kL/t U3O8 suggested by Mudd and Diesendorf (1).
TABLE 1. Annual Water Consumption and Uranium Production, Beverley Uranium Mine
year 2004 2005 2006 2007 total for period
3968
9
water consumption ML
annual production U3O8 equivalent
water consumption kL/tU3O8 equivalent
122 136 126 132
1084 977 825 748
113 139 153 176
516
3634
(average) 142
It appears that paper used the mine-plant wellfield circulation rate of 250 L/s to estimate water use. This is incorrect since this water is continually recirculated through the mine wellfields and processing plant. The values shown in Table 1 do illustrate the efficiencies of scale, in that while the water consumption has been relatively constant over the four years of data given, annual production has diminished and therefore water consumption per tonne of product increased. However, the lower production figures represent improved efficiency in another sense; they largely reflect the extraction of a greater proportion of uranium in the ground. This is achieved by mining wellfields for longer, extending the falling, quasi-exponential uranium extraction rate of individual wellfields. The length of time for which an individual wellfield is mined varies largely due to economics, i.e., when the sale price of uranium is higher wellfield life is extended, and vice versa. We also presume in Table 1 of Mudd and Diesendorf (1) that the “x%” twice next to the name of the Olympic Dam uranium project corresponds to the 100% and 20%, respectively, as per the figures and text. The inclusion of the 100% figures for Olympic Dam in that paper is inappropriate as the main product of that mine is copper which should be “assigned” the majority of the water use.
Literature Cited (1) Mudd, G. M.; Diesendorf, M. Sustainability of Uranium Mining and Milling: Toward Quantifying Resources and Eco-Efficiency. Environ. Sci. Technol. 2008, 42, 2624–2630. (2) Heathgate Resources Pty Ltd. Beverley Uranium Mine: Environmental Impact Statement-Main Report; Heathgate Resources Pty Ltd.: Adelaide, South Australia, June 1998. (3) Jeuken, B.; Ma¨rten, H.; Phillips, R., Uranium ISL Operation and Water Management under the Arid Climate Conditions at Beverley, Australia. In Mine Water and the Environment; Rapantova, N., Hrkal, Z., Eds.; VSB-Technical University of Ostrava: Karlsbad, Czech Republic, 2008; pp 487-490.
Peter H. Woods,* Susan D. Carter, and Ben M. Jeuken Heathgate Resources Pty Ltd, Suite 1, Level 4, 25 Grenfell Street, Adelaide SA 5000 Australia
Malcolm J. Wedd Quasar Resources Pty Ltd, Suite 2, Level 4, 25 Grenfell Street, Adelaide SA 5000 Australia * Corresponding author e-mail:
[email protected].
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 43, NO. 10, 2009
ES9002197
10.1021/es9002197 CCC: $40.75
2009 American Chemical Society
Published on Web 04/16/2009
