Hm. Fernandes et al., Acid rock drainage and radiological environmental impacts. A study case ofthe Uranium mining and milling facilities at Pocos de Caldas, WASTE MAN, 18(3), 1998, pp. 169-181
Acid rock drainage generated as a result of sulphitic minerals oxidation is
a source of pollution in many mining sites all around the world. This is t
he case at the Uranium Mining Site of Pocos de Caldas, Brazil. The present
study was aimed at studying the geochemical mechanisms involved on the mobi
lization of radionuclides from the waste rocks that occurs along with the a
cid drainage. The environmental radiological impacts caused by these pollut
ants were also assessed. It has been shown that precipitation of Ra and Pb
as sulfates was the most important mechanism in the reduction of both radio
nuclides activity concentration in the acid drainage. A result of this stud
y was that uranium isotopes were the most important radionuclides in terms
of the exposure of the critical group. It has been suggested that the recov
ery of uranium from the acid drainage would be a feasible practice, economi
cal aspects taken into account. It has also been estimated that pyrite oxid
ation will occur for more than a thousand years. The long time scale involv
ed on the oxidation of the pyritic material implies the need for the adopti
on of permanent remedial actions. To assess applicable remediation strategi
es it has been suggested that oxygen and temperature profile determinations
should be carried out in the dump. (C) 1998 Elsevier Science Ltd. All righ
ts reserved.