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Uranium What is Uranium Uranium Geology Uranium Deposits Uranium Resources Uranium Mining Uranium Logs

Uranium Mining


ISR mining

Mining is the removal of material for the purpose of extracting a commodity of interest (uranium, gold, aluminum, etc.). There are two methods used to mine uranium—conventional mining and the more modern alternative, in-situ recovery (ISR), described below. In Wyoming, uranium mining is primarily done by ISR. However, there are a few conventional mines planned for the future.

After mining, uranium ore is processed into yellowcake (U3O8), a type of uranium oxide concentrate powder obtained from leach solutions. Yellowcake then requires conversion to a gaseous form (UF6), followed by enrichment to fuel grade, and finally processing into fuel pellets, which are then used for electrical generation. In 2016, Wyoming produced more approximately 1.9 million pounds of yellowcake, ranking No. 1 in the nation.


Wyoming Uranium Mines

  • Comeco Resources, Smith Ranch-Highland, Converse County, North Butte operation in Pumpkin Buttes, Campbell County (mines with yellowcake processing)
  • Uranium One, Inc., Willow Creek, Johnson and Campbell Counties (mine and yellowcake processing plant)
  • Ur-Energy, Lost Creek mine, Sweetwater County (mine and yellowcake processing plant)
  • Uranerz Energy, Nichols Ranch, Johnson County (processing agreement with Cameco)
  • Strata Energy, Lance Project, Crook County

In-situ Recovery

ISR miningISR (also referred to as ISL or in-situ leach) is more economical and is considered to have a lower environmental impact than conventional mining. It is the preferred method of uranium mining if the uranium occurs in a shallow deposit hosted in porous and permeable sedimentary rocks. ISR dates back to the early 1960s in Wyoming’s Gas Hills and Shirley Basin uranium districts. The ISR method was developed on an industrial scale in Texas in the 1970s, and since 1993 has been the only uranium extraction method used in Wyoming.

ISR is essentially the reverse of the natural geologic processes that originally concentrated uranium in the ore deposit. Uranium deposits form through several steps: first, natural processes oxidize and leach uranium from source rocks, then surface water and groundwater transport the uranium to a reducing environment in a porous host rock where the uranium precipitates into mineral form. In the ISR process, the uranium minerals are oxidized, remobilized, and pumped to the surface. One of the advantages of this method is that there is very little surface disturbance other than the necessary infrastructure.

The ISR process removes uranium by pumping a mixture of water and oxidizing agents through the rock, including dissolved gases such as oxygen or carbon dioxide. The mixture, called a lixiviant, consists of water pumped from the orebody aquifer, plus the oxidizing agents added at the surface. In order to remove uranium from its location in the orebody, the lixiviant is pumped into the aquifer by injection wells, through the orebody, and back to the surface through extraction wells. The lixiviant frees the uranium from the orebody and into solution so that it can be removed at the surface by an ion exchange process. In addition to injection and production/extraction wells, ISR operations utilize monitoring wells, which continually sample the water at the margins of the orebody—laterally as well as above and below—to ensure that the injected water does not migrate away from the targeted ore zone and into adjacent aquifers.



Yellowcake

Conventional Mining

Conventional mining involves the physical removal of ore from the ground by surface (open pit) or underground mining. Surface mining requires removing overburden (topsoil, sand, gravel, etc.) down to the top of the orebody. Then the ore is removed by heavy equipment, loaded into haul trucks, and driven to the mill. Underground mining involves either adits (horizontal tunnels) or sinking a vertical shaft from the surface followed by driving adits at depth to reach the orebody. The main factors that determine whether to mine by open pit or underground are depth to the orebody and cost of production. Orebodies lying less than about 500 feet below the surface are typically surface mined as it is much cheaper than underground mining. After extraction, the uranium ore is transported to a processing plant where it is milled. This process involves crushing the ore, chemically extracting the uranium, and concentrating it into yellowcake.

Open Pit Surface Mine


Wyoming’s Uranium Drama: Risks, Rewards and Remorse - WyoHistory.org

The story of uranium in Wyoming is a high-stakes drama whose cast includes engineers and world-class mining companies. Uranium has been part of Wyoming’s economy since it was first discovered when the Cold War began and the U.S. government cornered the domestic uranium supply with a guaranteed price to producers. Read more...










Contact:
Robert Gregory (307) 766-2286 Ext. 237