How does in situ leach mining work?
In situ leach (ISL) mining of uranium involves the drilling thousands of boreholes spaced between 20 and 30 m apart, into the ore body in the underground aquifer.
Approximately two-thirds of the boreholes are for injection of a leach solution into the ore body and one-third for recovery of the pregnant mine-solution.
The leach solution consists of ground water to which a little sulphuric acid and oxidising chemicals are added. This takes 1-2 months to dissolve the uranium and is then pumped to surface by the recovery boreholes.
In the processing plant, only uranium is removed from the mine-solution. The remaining water is recharged with a little acid and oxidant and repeatedly recycled back into the ore body. As a result, the aquifer in the mine area becomes contaminated with high-grade dissolved uranium, dissolved radionuclides and dissolved heavy metals.
Large-scale use of the aquifer water by farming makes the likelihood of escape of the toxic mine solution beyond the mine area into the rest of the aquifer, high.
Approximately two-thirds of the boreholes are for injection of a leach solution into the ore body and one-third for recovery of the pregnant mine-solution.
The leach solution consists of ground water to which a little sulphuric acid and oxidising chemicals are added. This takes 1-2 months to dissolve the uranium and is then pumped to surface by the recovery boreholes.
In the processing plant, only uranium is removed from the mine-solution. The remaining water is recharged with a little acid and oxidant and repeatedly recycled back into the ore body. As a result, the aquifer in the mine area becomes contaminated with high-grade dissolved uranium, dissolved radionuclides and dissolved heavy metals.
Large-scale use of the aquifer water by farming makes the likelihood of escape of the toxic mine solution beyond the mine area into the rest of the aquifer, high.
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