Assessment of uranium release to the environment from a disabled uranium mine in Brazil

The Ore Treatment Unit (in Portuguese Unidade de Tratamento de Minérios - UTM) located in Caldas, MG, Brazil is a disabled uranium mine. Environmental conditions generate acid drainage leaching metals and radionuclides from the waste rock pile. This drainage is treated to remove the heavy metals and...

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Bibliographic Details
Published in:	Journal of environmental radioactivity Vol. 188; pp. 18 - 22
Main Authors:	Pereira, Wagner de Souza, Kelecom, Alphonse Germaine Albert Charles, da Silva, Ademir Xavier, do Carmo, Alessander Sá, Py Júnior, Delcy de Azavedo
Format:	Journal Article
Language:	English
Published:	England Elsevier Ltd 01-08-2018
Subjects:	Acid mine drainage Brazil Environmental impact assessment Mining Radiation Monitoring - methods Radioactive Pollutants - analysis Uranium Uranium - analysis Uranium mining Environmental impact assessment Uranium Uranium mining Acid mine drainage
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Summary:	The Ore Treatment Unit (in Portuguese Unidade de Tratamento de Minérios - UTM) located in Caldas, MG, Brazil is a disabled uranium mine. Environmental conditions generate acid drainage leaching metals and radionuclides from the waste rock pile. This drainage is treated to remove the heavy metals and radionuclides, before allowing the release of the effluent to the environment. To validate the treatment, samples of the released effluents were collected at the interface of the installation with the environment. Sampling was carried out from 2010 to 2015, and the activity concentration (AC, in Bq·l−1) of uranium in the liquid effluent was analyzed by arzenazo UV-Vis spectrophotometry of the soluble and particulate fractions, and of the sum of both fractions. Descriptive statistics, Z test and Pearson R2 correlation among the fractions were performed. Then, the data were organized by year and both ANOVA and Tukey test were carried out to group the means by magnitude of AC. The annual mean ranged from 0.02 Bq·l−1 in 2015 to 0.11 Bq·l−1 in 2010. The soluble fraction showed a higher AC mean when compared to the mean of the particulate fraction and no correlation of the data could be observed. Concerning the magnitude of the release, the ANOVA associated with the Tukey test, identified three groups of annual means (AC2010> AC2011 = AC2012 = AC2013 = AC2014 > AC2015). The mean values of uranium release at the interface installation-environment checking point (point 014) were within the Authorized Annual Limit (AAL) set by the regulator (0.2 Bq·l−1) indicating compliance of treatment with the licensing established for the unit. Finally, the data showed a decreasing tendency of U release. •The studied area (mine) suffers acid drainage that releases uranium from the sterile piles to the environment.•Before release, the effluent is treated with calcium hydroxide to adjust uranium concentration to the legislation.•An assessment of this release was made to certify compliance with radiological standards.•The releases of uranium were within the authorized values and suited the Brazilian and international reference levels.•There was a trend towards decreasing of uranium releases along the studied period (2010–2015).
ISSN:	0265-931X 1879-1700
DOI:	10.1016/j.jenvrad.2017.11.012