ISL and processing
While ISL mining, water is pumped to the surface of production wells that contain uranium at very low concentrations, the order of parts per million concentrations. The next step in the process of ISL is to extract the uranium-dicarbonate. The extraction takes place through the exchange of ions in a chemical processing plant. "The ion exchange process is very similar to a home Culligan ® water softeners," says Anthony. "It removes the hardness orCalcium from the water, filling it with soda, with ion exchange resins. If you go to Lowes or Home Depot and buy a water softener, you have basically a home version of a uranium extraction plant. "The main difference is having your water softener is a cation exchanger." For a uranium plant properly, you need to clarify an anion exchange resin, which was designed to use uranium exposure, "Anthony.
And what this magical "ion exchange resin" is? The resin isconsisting of small polymer beads, the particles are charged anions with an affinity for uranium. "There are literally millions of these tiny resin beads in a jar, can absorb the low concentration of uranium in solution," said Anthony. Adsorption is when something else attracted by something or clinging to them, like static electricity.
Why should the uranium, because this process? "In essence, the ion exchange process is a treatment (reduction) process, focusesconcentrated large amounts of low-grade uranium solution in a volume much smaller with a much higher concentration of uranium, "said Anthony. In other words, the treatment is only the concentration of uranium from large amounts of water they are in a compact reduced form. The preferred method is to ion exchange.
Anthony gave an example from the practice of the treatment process: "Three million gallons of diluted solution Wellfield concentrations of uranium, the100 parts per million less than 0.10 grams / liter, is passed through a bed of ion exchange resin. This could rise to 24 hours when the solution flows to 2,500 gallons per minute. After this period, the resin is loaded with about 2,500 pounds of uranium. "
Stripping of uranium
Stripping of uranium, the process is called elution. This is done through chemical exchange of positive and negative ions. Resins are ranked by the charge on theactive centers. "The active sites on the resin for positive and negatively charged anion to cation resins," Norris enlightens us. "The resin is capable of extracting ions from a chemical solution, which is an active site is derived," he continued. "In our case, the chloride ions from the salt obtained by the usual narrative temporarily stabilize or neutralize the positively charged active site." The negatively charged chloride ion attaches to the side of positive charge,held in place, which Norris called "electrostatic forces." If negatively charged ions such as uranyl dicarbonate are brought into contact with the solution, which will kick off the Chloride and replace it with the uranyl dicarbonate.
This was the chemistry lesson. Anthony took in a few words "is enough to move. There is a higher affinity for chloride ions on the resin for uranium. Thus, the uranium is removed from the resin bed." Treatmentfacility chemically strips the loaded uranium from the resin by soaking the entire package of uranium-laden resin in a salt bath solution. "The volume of salt solution is on the order of 10,000 gallons resulting in a solution concentration of 30 grams/liter uranium," Anthony said, describing the process of how the uranium becomes concentrated. "The stripped uranium solution concentration is magnified 300 times more than the wellfield solution," he informed us. "The concentration level can now be economically processed for recovery: precipitation, dewatering, drying and drumming for a nuclear facility."
GETTING URANIUM INTO THE DRUM
After the uranium has been removed from the solution, it is precipitated. At this point in the processing stage, you have yellowcake slurry. Up close, it looks like a sort of yellowish and wet, runny cement mixture. The dewatering process does just that, it removes the water from the yellowcake mixture.
"I use a filter press, a device that is designed to separate solids from solutions," explained Anthony. Filter presses are extensively used in various types of food, chemical and drug processing across the world. "The uranium solids, now looking more like yellowcake, are retained in the filter press, where they can be washed and later air dried, before drying them to a powder with a low temperature vacuum dryer," said Anthony taking us step by step through this process.
So what is the filter press and how do you end up with the finished yellowcake when you're done? "It's a series of plates and hollow frames, or it could be a series of recessed chambers," Anthony answered. "Filter cloth is draped over the plates or chalked in the recessed chambers. The yellowcake slurry is pumped through the filter allowing the liquid phase to pass through the filter cloth, trapping the uranium oxide inside the device." Anthony likes to pack the filter press up with as much yellowcake as it can hold. "It is then washed with clean water to displace the chloride ions to a low level," Anthony explained. If you don't remove the chloride concentrations to the acceptable level required by an uranium enrichment facility, a fine is assessed against that shipment.
The final steps include conveying the yellowcake to the vacuum dryer. The uranium oxide's color depends on how high or low a temperature is used to dry the "yellowcake." Patrick Drummond, the Smith-Highland Ranch plant superintendent, showed us pure uranium oxide dried at high temperatures. It was nearly black. After the drying process is complete, the uranium is packaged up in DOE-approved 55 gallon drums and transported to an enrichment facility. It is then when the enriched uranium can finally be used to power a nuclear reactor and provide an inexpensive source of electricity.
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