Word Count:
1504
Summary:
We talked to North America's leading In Situ Leach (ISL) uranium mining engineers, and had them explain exactly how ISL worked. Most of the significant ISL operations in the United States were designed and/or constructed by these engineers. They explained how ISL mining is really just reversing the process of Mother Nature.
CLEANING UP THE PROJECT
Not so fast. Shipping the uranium out of the ISL plant isn't the final step. The water has to be cleaned up, the property re...
Keywords:
uranium, uranium mining, energy, nuclear energy, electricity, ion exchange, ISL mining, utilities
Article Body:
We talked to North America's leading In Situ Leach (ISL) uranium mining engineers, and had them explain exactly how ISL worked. Most of the significant ISL operations in the United States were designed and/or constructed by these engineers. They explained how ISL mining is really just reversing the process of Mother Nature.
CLEANING UP THE PROJECT
Not so fast. Shipping the uranium out of the ISL plant isn't the final step. The water has to be cleaned up, the property returned to its original condition. If done properly, then the footprint of the ISL uranium operation should have been nearly erased. In an earlier article, "Wyoming Uranium: Now and the Future," we talked to Pat Drummond at Smith Ranch about this process:
The company is meticulous in restoring the landscape as well. Any restoration work on the surface is called "reclamation." That can involve farming. "When we start a well field, we have to, by license, remove the topsoil and store it somewhere," Drummond explained. "When we go back to reclaim the property, we take all the pipes out, we take the houses down, and cut our wells off. It's all identified. We put an ID marker on the well. In 50 years time, when Farmer Joe comes around and wonders what was there, the state can say, 'That was a uranium well.' From the time we've stopped mining, we put everything back to normal."
The one item we did not address at the time was cleaning up the water after the orebody has been mined out. Why is restoring the water back to background important? "In the mining process, you're basically elevating sulfate," explained Anthony. "You're also elevating calcium because you're lowering the pH a little bit, down to 6.5 to 7. Because you run it across the ion exchange circuits, you get a little leakage of chlorides into the lixiviant." Subsequently, the water will have sulfate, chloride, calcium and bicarbonate circulating within it. "When you add carbon dioxide, you're forming bicarbonate," Anthony noted. "These are the major ion groups you are elevating during the mining process." He also added that in some projects, you may get arsenic, vanadium and/or selenium. "They all go into the solution so that at the end of your mining process, these ions will be elevated above their baseline values." The water will need to undergo a purification process to return them back to a quality consistent with baseline values."
What does the ISL operator do with the water once the facility has mined out the uranium? There are three options, which we discussed with Glenn Catchpole, who has also set up previous ISL operations. In 1996, Catchpole was the General Manager and Managing Director of the Inkai uranium solution mining project in Kazakhstan. He is currently the Chief Executive of Uranerz Energy. "Here's my order of priority: If you have a receiver formation for deep disposal on your project, that's my first choice." Sometimes, a project may not have access to a deep disposal aquifer, warned Catchpole.
The water is sent down the receiver formation, down about 4000 feet. "You're usually sending this water to a formation that is very briny, a poorer quality than what you're sending down," Anthony pointed out. Another option, according to Catchpole, would be operations ponds, or evaporating ponds, where the water is evaporated. A third option is "land applied." Catchpole explained this was for land application. "You take your waste stream, you treat it to remove the certain level of impurities, according to the government requirement, and then you're allowed to disperse it on the land surface, as if you were irrigating." When applied to the land, it is soaking into the land. "It's growing grass, and it's going into the groundwater system," concluded Catchpole, "Whatever water quality standard they allow for you to put that water in the land, they want to ensure it doesn't accumulate some particular chemical over time that is going to build up and contaminate the land."
Generally, during the restoration process, the water is circulated through the barren orebody about eight times. It's another instance of pore volumes – eight more times through the sandstone formation. Anthony explained, "Normally, the first pore volume is evacuated and disposed of via a disposal well." But he warned, "This will cause an inflow of surrounding native water back into the mine zone. The resulting water is pumped to the surface and processed through a reverse osmosis unit." Anthony compared this to the desalination of seawater. "The reverse osmosis equipment acts like an 'ion filter,' allowing pure water to pass through a membrane and filtering out ions of sulfate, calcium, uranium, bicarbonate and so forth," Anthony explained.
Two streams of water are produced by the reverse osmosis unit. One stream is called "product water," and is normally consistent with drinking water quality. The smaller stream of water is called "brine." It contains, according to Anthony, "95 percent of all the dissolved ions that were in solution." He said, "The brine is disposed down a deep well into an underground formation, which is typically not suitable for any use."
CONCLUSION
For all the lip service and media attention paid to the environmental movement in terms of financial support, recognition and respect, it is the ISL miner who cares more about the environment, about preserving Mother Nature. Environmentalists remain ignorant of, or care not to publicize, the dangers of coal-fired electrical generation. Mining and burning coal to generate power for industry and residential electricity poses a greater threat to Mother Nature than ISL mining and nuclear power-generated electricity. No more evident a case in point is New Mexico, where the Navajo Nation "banned" uranium mining, because their president was misled by environmentalists in believing ISL uranium mining could pose a threat to groundwater. At the same time, the Navajo Nation enjoys over $100 million in coal royalties each year, as their air is polluted by carcinogens filling their air from coal mining in the San Juan Basin and coal-fired plants, which produce most of their electricity. It is time for the world's environmentalist movements to wake up and smell the air they are breathing.
Unfortunately, ISL uranium mining will not replace conventional uranium mining in many deposits across the world. According to the World Nuclear Association, ISL mining accounted for 21 percent of worldwide uranium mining in 2004. "The overriding constraint of ISL is the technology is only applicable to selected uranium deposits," Stover cautioned. "It's those deposits wherein the uranium ore resides in a permeable environment, where you can flow water through the deposit and where you can bring the dissolved oxygen and carbon dioxide into contact with the uranium." Stover explained that, during the evolution of ISL mining, a number of projects failed because the uranium was associated with organic material, was not accessible to the leaching solution, or the uranium was tied up in clays or shale-like material. "They were not able to flow fluid through it," explained Stover. "The key issue at the onset is a careful characterization of the host environment in which the uranium exists."
The key advantage to ISL is the far lower capital costs to start up a project, compared to the hundreds of millions required for a conventional mining and mill complex. For example, UR-Energy's William Boberg and Uranerz Energy's Glenn Catchpole both believe they can install an ISL operation on their Wyoming properties for as little as $10 million. Labor costs are also less. Doug Norris pointed out, "In its heyday, the Highland mine probably had 4,000 working in it." By comparison, Cameco's Smith-Highland ranch in Wyoming may soon ramp up to nearly 100 employees. "We're talking about installing a centralized water treatment plant supported by a large number of water wells, typically completed with PVC," Stover explained. "That's in contrast with conventional mining, where you have extensive earth moving, in the case of an open pit or extensive underground workings, and a more complicated, much larger processing plant."
In terms of environmental impact, ISL offers something sensible to the environmentalists. "ISL is much less intrusive, and it is short lived," Stover said, echoing the sentiments of all who have been involved in this type of uranium mining. "It's acceptance by the general public is much more favorable," he concluded.
What does the future hold for ISL uranium mining in the United States? "Up until 2004, prices were flat," Norris pointed out. "The economic picture has just now switched to where mines can start coming on again, but it does take years to properly define where the ore is. It takes a lot of geologic drilling and time to decipher it. Then there are the regulatory requirements, and that can take several years. Even if everybody reacted right now to what's out there, it would still be several years, upwards of five years, before production jumped from its existing rate to 10 to 20 million pounds at the most."
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