SOURCE: RAWLINS DAILY TIMES
DATE: OCTOBER 2, 1997
SWEETWATER URANIUM MILL READY TO PICK UP WHERE IT LEFT OFF
Sweetwater uranium mill ready to pick up where it left off
By Tori Adams
Times staff writer
RAWLINS - When the Sweetwater Mill resumes processing uranium, it still will be a state-of-the-art facility despite being mothballed for 14 years.
Foreman George Palochak said the Sweetwater Mill "is a very modem mill. It was state-of-the-art when it was put in operation in the early 1980s and milling techniques haven't changed much since then."
The mill northwest of Rawlins is the only conventional uranium mill in Wyoming and one of six operational conventional mills in the United States. The others are in Utah, Colorado, New Mexico and Washington State.
The Sweetwater Mill can process about 4,000 tons of ore per day into about 3,000 pounds of concentrated uranium called yellowcake per day, he said.
It was placed on standby in 1983 and may resume operating as soon as next fall if Kennecott Uranium Company's application for an operating license is granted by the Nuclear Regulatory Commission.
Palochak said uranium ore enters the huge plant in the form of chunks of sandstone at one end for chemical processing and yellowcake comes out the other end.
The yellowcake is packed in barrels and sent to plants that extract the form of uranium used in nuclear reactors and shape it into fuel rods, he explained.
The sandstone that contains uranium is ground as fine as beach sand and placed in vats containing hot water, sulfuric acid and sodium chlorate. The sulfuric acid is a byproduct of Kennecott's copper smelter in Salt Lake City.
"Chemically, we make a kind of soup out of it," Palochak said of the uranium leaching process during a tour of the inactive facility Monday.
After about 16 hours of being stirred around in the acid soup, the water, which now contains 95 percent of the uranium that was 'in the sandstone, is decanted off the top of the vats, he said.
The sand, which is now barren o uranium, settles, the water is drained off and the sand is dumped into tailings impoundments near the plant.
Mill Manager Oscar Paulson said much of the water used in the process is recycled because evaporating water in tailings ponds is much more expensive than reusing it.
The design and proper maintenance of the tailings ponds may be the most complex and expensive part of the entire mining and milling operation, he added.
Palochak, who has many years of experience in the uranium industry, said the acidic water that contains the uranium is pumped to a special building where kerosene and alcohol are used to remove the uranium from the water.
The special building is needed because the solvents are flammable and potentially explosive, he explained.
A chemical called an amine that attracts uranium is dissolved in the kerosene and the solution is agitated to mix it with the water so the uranium is exposed to the amine, he said.
The water and any contaminants it still contains sinks under the thin layer of kerosene so it can be drained off and much of it can be filtered and reused in the process.
Neutralizing this acidic solution causes the uranium to settle out of the solution so the ammonium sulfate can be drained off, he explained.
The resulting yellowcake powder is dried and packed in barrels for shipment to plant that process it into fuel rods used in nuclear power reactors.
Because the uranium is processed in water or kerosene until it is ready to be packed, Palochak said there are no safety hazards from airborne uranium dust or radon.
The packing is done by remotely controlled machinery in a sealed environment and operators who occasionally need to enter the packing room wear respirators, he added.
Mill workers, and even guests touring the facility, sign in and out and must check themselves with a meter that measures alpha radiation emitted by uranium every time they leave the mill building.