83
and the Denison Mines Ltd. (1957–1992) produced about 70 MT of waste (OECD
2014). By 1976, the entire Serpent River was badly contaminated with acid and
radioactive wastes. Alone in 1978, more than 30 tailing dam failures were reported.
Moreover in August 1993, 2 million litres of contaminated water spilled as a power
failure from a Rio Algom’s Stanleigh mine tailings.
Nevertheless with the passing of time and awareness for human health and the
environment, the uranium mining practices have also changed in Canada. The Key
Lake operation has set an example evolved over several decades of operation. A
sustainable management of water has remained a key issue for uranium mining.
Hence, the collection of radionuclide metal-contaminated water is treated within
mill effluent treatment system. The source of contaminated water can be used water
from reverse osmosis (RO) plant, runoff and seepage water from ore containment or
special waste containment areas and the runoff water from the mill terrace. The
environmental monitoring infers that the aquatic impacts do not extend beyond the
boundary of facilities and are within effect levels predicted. The raffinate obtained
after the solvent extraction (SX) operation of the pregnant leach liquor is also treated
with lime to adjust the pH and removal of heavy metals as their precipitates. BaCl 2
is used to precipitate Ra-226, while H 2 O 2 is used to control the organic contaminants that inadvertently carry over from the SX circuit. All the treated effluents are
first stocked in the monitoring ponds, and only after determining the water quality
it is released to the environment; otherwise it is sent back for retreatment. Recently
added low-pH thickening could significantly control the molybdenum and selenium
into the effluent. Notably, the environmental conditions have improved since the
open-pit mining operations ended to control the on-site activities of blasting, grinding and transportation that are not needed in present-day milling operation. In the
case of tailing management, Canada has better facility as well (Frey et al. 2010).
The McClean Lake operation operated by Areva (Canada) is a leading example
since 1999, treating the tailings generated by processing of five different ore deposits. Arsenic is the major contaminant therein the tailings in the range of 0.2–
20 mg g
−1
(Rinas et al. 2010).
The national regulatory body, Canadian Nuclear Safety Commission (CNSC
2010), extensively monitors the environmental effects by the activities of uranium
mining, milling and processing facilities, identifies their potential impacts on receiving environment and ensures that licensees are taking all reasonable measures to
control the contaminant releases. Effluent and environmental monitoring programmes have been imposed on a risk basis depending on the complexity contaminant released. In addition to regularly reporting the site-specific environmental
effects, the Canadian companies involved in uranium mining have instituted a
community- based environmental monitoring programme. The programme allows
local habitants to assist in identifying the sampling points, sample collections and
evaluation of the monitoring data. By the support of the provincial government, the
Environmental Quality Committees have been established to improve communication between the industry, government and local habitants. Such activities help to
establish the trust in local population that uranium mining does not pose a health or
environmental risk.
Environmental and Health Impact Due to Uranium Mining
and the Denison Mines Ltd. (1957–1992) produced about 70 MT of waste (OECD
2014). By 1976, the entire Serpent River was badly contaminated with acid and
radioactive wastes. Alone in 1978, more than 30 tailing dam failures were reported.
Moreover in August 1993, 2 million litres of contaminated water spilled as a power
failure from a Rio Algom’s Stanleigh mine tailings.
Nevertheless with the passing of time and awareness for human health and the
environment, the uranium mining practices have also changed in Canada. The Key
Lake operation has set an example evolved over several decades of operation. A
sustainable management of water has remained a key issue for uranium mining.
Hence, the collection of radionuclide metal-contaminated water is treated within
mill effluent treatment system. The source of contaminated water can be used water
from reverse osmosis (RO) plant, runoff and seepage water from ore containment or
special waste containment areas and the runoff water from the mill terrace. The
environmental monitoring infers that the aquatic impacts do not extend beyond the
boundary of facilities and are within effect levels predicted. The raffinate obtained
after the solvent extraction (SX) operation of the pregnant leach liquor is also treated
with lime to adjust the pH and removal of heavy metals as their precipitates. BaCl 2
is used to precipitate Ra-226, while H 2 O 2 is used to control the organic contaminants that inadvertently carry over from the SX circuit. All the treated effluents are
first stocked in the monitoring ponds, and only after determining the water quality
it is released to the environment; otherwise it is sent back for retreatment. Recently
added low-pH thickening could significantly control the molybdenum and selenium
into the effluent. Notably, the environmental conditions have improved since the
open-pit mining operations ended to control the on-site activities of blasting, grinding and transportation that are not needed in present-day milling operation. In the
case of tailing management, Canada has better facility as well (Frey et al. 2010).
The McClean Lake operation operated by Areva (Canada) is a leading example
since 1999, treating the tailings generated by processing of five different ore deposits. Arsenic is the major contaminant therein the tailings in the range of 0.2–
20 mg g
−1
(Rinas et al. 2010).
The national regulatory body, Canadian Nuclear Safety Commission (CNSC
2010), extensively monitors the environmental effects by the activities of uranium
mining, milling and processing facilities, identifies their potential impacts on receiving environment and ensures that licensees are taking all reasonable measures to
control the contaminant releases. Effluent and environmental monitoring programmes have been imposed on a risk basis depending on the complexity contaminant released. In addition to regularly reporting the site-specific environmental
effects, the Canadian companies involved in uranium mining have instituted a
community- based environmental monitoring programme. The programme allows
local habitants to assist in identifying the sampling points, sample collections and
evaluation of the monitoring data. By the support of the provincial government, the
Environmental Quality Committees have been established to improve communication between the industry, government and local habitants. Such activities help to
establish the trust in local population that uranium mining does not pose a health or
environmental risk.
Environmental and Health Impact Due to Uranium Mining