Crow Butte

Overview

Crow Butte was discovered in 1980 and began production in 1991. It is the first uranium mine in Nebraska, USA and is a significant contributor to the economy of northwest Nebraska.

Cameco acquired an initial interest in the operation in 1994 and became the sole owner in the year of 2000.

Crow Butte uses environment-friendly in situ recovery (ISR) mining technique to extract uranium and receives ISO 14001: 2004 Certification. The mine has proven and probable reserves total 3.7 million pounds U₃O₈ and annual production capacity of 1 million pounds U₃O_8.

The mine produced 0.8 million pounds U3O8 in 2011. It employs 69 people.

Location

Crow Butte mining operation is located 460 km northwest of Lincoln, Nebraska, USA.

Nebraska is an American state located on the Great Plains of the Midwestern United States. Its state capital is Lincoln. The state's economy is dominated by agriculture.

Geology & Mineralization

Uranium occurs in aquifers hosted by permeable and porous sandstone beds as coatings on the constituent sand grains.

The mechanism for deposit formation is dissolution of uranium from the formation or nearby strata and the transport of this soluble uranium into the host unit. When the fluids change redox state, generally in contact with carbon-rich organic matter, uranium precipitates to form a 'front' which is a crescent shape ore body that transects the host lithology.

Crow Butte mineral reserves were estimated at 1,282.6 kt grading 0.13% U3O8 for 3.7 Mlbs U3O8. (December 2011)

Mining & Operation

The Crow Butte operation uses the in situ recovery (ISR) mining method. ISR mining produces no waste rock or tailings and results in minimal disturbance to the surface and underground areas mined.

Uranium at Crow Butte occurs in sandstone aquifers as coatings on sand grains at up to 300 metres underground. Uranium is removed using a grid of injection and production wells.

The uranium is insoluble in the native groundwater. Small amounts of oxygen and bicarbonate (baking soda) are added to the injection stream to dissolve the uranium. 

Processing

The Crow Butte operation uses the in situ recovery (ISR) mining method that produces no waste rock or tailings and results in minimal surface disturbance.

The uranium solution, less than 1/10 of 1% uranium, is then pumped from a production well to a satellite facility where the uranium is transferred to ion exchange resin beads similar to the sand from which it was extracted. The uranium-bearing resin is then pumped to a processing plant where it is removed from the beads, precipitated and dried to become the final product, yellowcake.

This is essentially a closed-loop recirculation system. Water from the production wells is reintroduced in the injection wells. Slightly less water is injected than withdrawn to ensure the fluids are confined to the ore zones intended for extraction. Monitor wells are installed to allow testing of groundwater quality above, below and around the target zones to ensure fluids do not move outside those areas.

Environment & Community

Cameco's US operations employ the environment-friendly in situ recovery (ISR) mining method. 

The uranium at all three sites occurs in sandstone aquifers located up to 300 metres underground .It is extracted by pumping natural groundwater mixed with small amounts of oxygen and carbon dioxide into the ore zone to dissolve the uranium. Uranium-bearing solution is pumped to the surface and piped or trucked to processing plants where the uranium is recovered.

ISR mining produces no waster rock or tailing and results in minimal disturbance to the surface and underground areas being mined. It also minimizes workers' exposure to radiation. Water used in the process is recycled back into the operation.

Once operations are complete groundwater is restored to regulatory standards.