IN-SITU RECOVERY MINING (ISR)

Uranium has been produced in Texas for more than 50 years. (See Texas State Historical Association article.) But long before any uranium mining activity can begin, a lease with the landowner must first be negotiated. After a lease is signed, a drilling permit, outlining the details of the target area, must be obtained from the Surface Mining Division of the Railroad Commission of Texas, which has regulatory oversight of all uranium exploration drilling in this state. Monthly reports are filed with this agency updating the regulators on the progress of the exploration. In addition, agency inspectors make regular, unannounced site visits to verify compliance.  Their monthly reports confirm that the company consistently meets or exceeds all operational requirements.

A pattern of wells are drilled in the target area. Well logging equipment, along with core samples from the well, are used to identify the presence and concentration of uranium. In addition, the entire underground geological structure is thoroughly examined. Once the drilling program is complete, the information is analyzed. If sufficient uranium ore is not present, the wells are plugged and the lease is allowed to expire.

PERMIT APPLICATION

However, if an ore body is identified, the next step is to develop a permit application. Detailed information is gathered for the application, including weather data, underground conditions for both water and geological formations, an archeological survey, environmental assessment to determine what types of plants and animals are found in the area and a socio-economic analysis is done to project the economic impacts on the local economy. The information is included in a Mining Permit Application submitted to the Texas Commission on Environmental Quality (TCEQ).

Once submitted, the TCEQ staff will confirm the application has all the required information. Professional staff members will examine and evaluate the information provided. Ultimately, the staff will make a recommendation to the TCEQ Commissioners to grant or deny the production permit.


PRODUCTION


In Situ Recovery (ISR) is a mining technique that dissolves uranium from porous sandstone aquifers by reversing the natural processes which originally deposited it. ISR is noninvasive and has a much smaller environmental impact than traditional open pit mining.

Based on the dimensions of the underground ore body, a series of production and injection wells are drilled and completed. A recovery solution, consisting of native ground water enhanced with oxygen and carbon dioxide, is pumped into the injection wells. Alternating production wells extract slightly more water than is pumped through the injection wells, drawing the water through the underground ore body and washing the uranium out of the sandstone and into solution, where it is pumped to the surface. This insures that all underground migration of ground water is towards and through the ore body. As an added protection, monitor wells are strategically located outside the production area and are checked regularly.

The uranium-bearing water that is pumped out of the formation is processed through an ion exchange column (similar to a home water softener, only much bigger) that strips the uranium from the water. Additional processing dries the uranium into a product referred to as “yellow cake,” which is packed in 55-gallon drums. It is important to note that at this point, the yellow cake contains less than one percent U235, the component required to make fuel pellets for a nuclear power plant. Much like crude oil, it has to be refined into a beneficial fuel product.

RESTORATION

When recovery operations have been completed, the quality of the aquifer must be restored to a baseline standard determined before the start of the operation, so that any prior use can be resumed. The existing facilities are used to restore the affected ground water. Some of the wells draw water from outside the production area. The water that is pumped out of the formation during restoration is treated and filtered, and the clean water is reinjected. Groundwater restoration continues until regulatory agency officials determine that quality standards have been achieved. Once that determination is made, wells are closed, process facilities are removed, any disturbed surface areas are revegetated and the land returns to its previous uses.

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