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Kingsville Dome Plant, Kleberg County, Texas

This is not what most people picture when they hear about a mine, but this is the mine as it appears with in-situ technology. Green areas surrounding the plant are URI property; the darker fields in the distance are plowed fields waiting for crops to be planted by our farming neighbors.

The Ore Body: How It Forms

The original source of uranium is volcanic rock. Uranium enters an aquifer when rainwater, which contains oxygen and carbon dioxide from the air, percolates down from the soil surface, through uranium-bearing volcanic material and into the porous rock of the deeper aquifer. The uranium will stay dissolved in the groundwater, migrating through the rock, until it contacts something in the rock such as carbon, which takes away the oxygen. This process is called a “reduction” and causes the uranium to precipitate. Huge amounts of groundwater containing the dissolved uranium pass this reducing interface in the sandstone rock, and the uranium accumulates as it drops out of solution. It takes millions of years for a commercial-grade deposit to accumulate. The process is still continuing today.

Schematic of the Recovery Process

In-situ recovery (ISR) removes the uranium from the rock like nature does. We add oxygen and carbon dioxide (similar to the club soda that you drink) to the groundwater and circulate this water through a series of injection and extraction water wells until the uranium in the sand of the aquifer has been depleted. The original rock stays in place (in situ), and only the mineral is removed through the wells. These water wells are just like the water well used to supply water to an individual home.

Chemicals Used for In-Situ Recovery

These are the ingredients used during our mining process. We use a mild carbonate solution plus oxygen to wash the oxidized uranium from the sand grains. This carbonate solution is the same chemical composition as club soda, or as a dilute mixture of baking soda and water. We choose this type of solution because it has minimal impact on water quality.

Laboratory Technician at Work

In the lab, the technician carefully measures water quality as part of monitoring. The systematic monitoring continues throughout both production and restoration.

The Wellfield Is the Mine

This photo shows a completed in-situ wellfield with numerous injection and extraction wells. These wells are operated in balance, together as a mine unit to recover the uranium ore. In the foreground, monitor wells can be seen as they encircle the wellfield.

Conventional Mining Site

Compare this photo of a conventional mine with the previous one showing a solution mining operation. Uranium can be recovered by either method, but in-situ methods result in much less surface disturbance, less dust, less hazardous working conditions, and in-situ does not require de-watering the aquifer.

Former Wellfield at Benavides Location

After production has ended, the water used in mining is cleaned up, the wells are plugged and the tops removed, then the surface is reclaimed. This is a view of the reclaimed wellfield at our former Benavides location.

Separating Soil by Layers

During drilling, it is necessary to excavate pits to contain drilling fluids. The drilling fluid circulates within the well bore during drilling, acting as a lubricant for the drill bit, a conditioner for the well bore, and a flushing system that removes the rock cuttings from the well. We are very careful to separate the soil layers as we remove them. The difference in soil type is readily apparent from its color, as shown in this photo. Once drilling is complete, the soil layers are returned to the pit in their proper order with the rich topsoil at the surface.

Water Well Rotary Drill Rig

Drilling is done with a rig commonly used to drill water wells for home, farm, or ranch use. We use this rotary drill rig, whether we're doing exploration drilling or production drilling of wells that will be cased and cemented and then used as either extractors.

Full-Scale Drilling of a Wellfield

For a short period of time during wellfield development, a number of drill rigs are in operation at once. A typical wellfield has about 160-175 wells operating, so developing the wellfield is a labor-intensive effort. Here, development of PAA #1 at Kingsville Dome shows six rigs working and another getting set up.

Drill Core Split in Half and Opened Up

Drilling activities provide information that is evaluated by the staff of geologists and engineers. Sometimes we bring a “core” of rock up from the aquifer to study. This photo shows a core sample where rust-colored “oxidized” sand (on the right) meets gray-colored “reduced” sand (on the left). Core samples with this interface are a favorable indication that the uranium is producible by the ISR process.

Cuttings Samples

The drilling process provides valuable information to the geologists. “Cuttings” are the bits of rock washed out of the wellbore to the surface during the drilling process. These samples are collected at regular intervals during drilling for analysis by geologists. Here we see the obvious difference between the buff-colored “oxidized” sand and the gray-colored “reduced” sands.

Inside a Geophysical Logging Truck

In the field, a geophysical log is needed for every well. A specialized logging tool is run down each well, and the data is recorded on a continuous graph. These logs were originally developed for the oilfield. Valuable scientific information is acquired about the subsurface rock, which allows geologists and engineers to evaluate the formation at the drill site.

Geologist Compares Geophysical Logs

A geologist analyzes geophysical logs from many wells. The geological staff works day and night, reviewing the results of the drilling activity. Every day, the geologists provide drillers with new drill locations.

Future Production Wells are Cased and Cemented

Monitor wells and wells that are used during “mining” (either as an injector or an extractor) have casing cemented into the wellbore, which will later be opened through the mineralized interval. We use special plastic or fiberglass casing; the oxygen added to our mining fluids would rust steel casing.

Geologist and Wellfield Foreman

After evaluating data from geophysical logs, the exact location of the mineral is determined. The geologist will then give detailed instructions to the wellfield foreman so the casing is properly installed.

Graded Drill Site

Once drilling work has finished, the process of returning the area to its natural state begins. First, the piles of soil that were carefully separated during excavation are returned in their proper sequence, so that the rich topsoil is at the surface, and the area is contoured, graded, and seeded.

No Sign of Drilling Remains

Once the reseeded plants have become established, there is no sign of the drilling activity that took place, except for the wellhead (the white pipe) which is visible above the surface of the soil.

Proving a Well Can Produce Water

After a well is cased, it is tested to be sure it will produce water properly. Water from this test is sampled and carefully analyzed by an independent lab before ISR operations begin. It will be sampled again and again during production.

Monitor Well in a Corn Field

Monitor wells, drilled into the mine zone, ring the in-situ wellfield at a distance of about 400 feet. There are additional monitor wells in zones above the ore zone, and, if needed, below the ore zone. Here the well is surrounded by a corn crop during the growing season. Agricultural activities - farming and ranching - coexist with in-situ activities because there is very little impact on the surface soil or neighboring properties.

After the Drilling

After drilling activity is complete and the wellfield is operating, the wellfield is a quiet and pleasant place to be.

Wellfield Piping

Production wells (extractors) feed into a network of wellfield pipes that deliver water carrying dissolved uranium to the ion exchange plant. A separate pipeline returns water to the wellfield after the uranium has been removed, and the water is recycled into injector wells to continue the mining process.

Oxygen Injection Equipment at a Mine Site

Oxygen is added to the injection water to oxidize or “rust” the uranium ore. When oxidized, the uranium is mobile and will move with the water to the extraction well. Then it can be pumped to the surface, where it is recovered and concentrated.

Completed Injection Well

After the casing is installed and cemented into place, it is used for either injection or extraction. This well will be used for injection. The blue hose that goes into the well bubbles oxygen into the water, which will oxidize or “rust” the uranium so it will dissolve into the water, flow through the formation, and be removed through the extraction well.

Reservoir Engineers Use Computer Simulations

The engineering staff is responsible for the wellfield. They maintain detailed records and run simulation software to verify that the injection and extraction wells work together in proper balance. Coupled with regular sampling from the wells themselves, this assures a safe operation.

Pathline Simulation

This Pathline Simulation Map shows the injection and extraction wells have been carefully placed across the ore. Monitor wells surround the zone, aligned with the ore body. The size and shape of the ore body determine the number and location of wells; 168 wells are shown on this example, average for a roll-front ore body.

The looping lines on this map show the path of water movement through the ground as time passes. The model tracks the flow of fluids within the mine zone, demonstrating how fluids are confined to the area. Pathlines from the monitor wells track flow into the active zone, due to the “pressure sink” that is intentionally created by extracting slightly more water than is injected.

Rosita Process Facility

The Rosita Plant was successful in producing ore during the 1990s and will be used again in the future. As with the Kingsville Dome site, neighboring land owners can continue with their farming or ranching activities with confidence that they will be unharmed by the mining operations. Here the land owner grazes cattle just outside the plant site.

Ion Exchange System

These are the ion exchange columns at our Kingsville Dome location. These columns are filled with resin beads that remove uranium from water in the same way a water softener in a home removes minerals that cause hard water. The facility is really just a giant-sized water softener.

Resin Beads Fill the Columns

This photo shows the resin beads that fill the columns at the operating plants. They look like tiny red or amber beads. The beads in a home water softener will look very similar, although they are usually sealed in a tank and the home owner doesn't see them.

Washing the Uranium Off the Resin Beads

After the ion exchange resin is loaded with uranium, it will be washed with salt water to remove and concentrate the mineral. The salt water is then treated with hydrogen peroxide (just like you buy in the drug store) to precipitate the uranium out of the solution. Uranium in solution turns the water a yellow color.

Large Water Softener as Nest Structure

The scaffolding allows access for work on the top of the column. At our Longoria location, this scaffolding provided a solid base for nesting Scissor-tailed Flycatchers, who built a nest on one of the steps. Workers carefully stepped around the nesting birds, and a clutch successfully fledged from the nest. The nest was so successful that the birds returned for several more years, and always reared young from the nest on the step.

Quality Control and Safety

We maintain full-service wet laboratory capabilities at our production locations. The laboratory facility is an important factor in maintaining quality control for production. Detailed procedures are carefully followed for analysis of production fluids.

Reverse Osmosis Equipment

After in-situ recovery is complete, the wellfield water is processed through a reverse osmosis filter. This filter removes dissolved minerals that have become elevated during the mining process and returns the ground water to pre-mining quality. Reverse osmosis is a proven technology that is used for most of the bottled water that is sold as “drinking water,” and small units are sold for use within a home to improve drinking water quality.

Reverse Osmosis Maintenance

The Reverse Osmosis (RO) unit is carefully maintained and monitored during operations. Once the unit has been inspected and adjusted, if needed, the operator will take a water sample to the lab for quality control testing. Small units that are used in the home probably only need maintenance work once or twice a year, but large commercial units have more frequent maintenance scheduled.

Safety Is Our First Concern

Each employee has an individual dosimeter, which is worn while they are at work to document their radiation exposure. The exposure is so low that we are not required to wear dosimeters by regulation.

Yellowcake on Filter Cloths

Once the uranium has been precipitated, the salt water is filtered through fine cloths, and the solid uranium is removed.

Filter Press Operator

Although the uranium is very low in radioactivity, we still follow extremely strict safety procedures to protect our employees. The operator shown above is suited in protective clothing while working with the filter press. Texas regulations require that dosimeters be worn if exposure is over 500 millirems/year. However, our employees are exposed to less than 2 millirems/year; yet we require all employees to wear dosimeters so that we can document their very minimal exposure. This very low level is surprising to many people with concerns about radiation exposure.

Vacuum Dryer

We use a vacuum dryer to remove remaining water from the filtered uranium. There are no emissions to the environment from such a dryer due to the vacuum that is maintained. This type of dryer is also used by the food industry because it keeps environmental impurities out of food during processing. The protective suits worn by workers at this stage of processing are similar to those used in the food industry, as well. The suit is a thin layer of tightly woven fabric, which keeps fine dust particles off the worker's clothing or skin.

Uranium in Drums

The dried uranium is packaged into drums, ready for shipping. The drums will be delivered to our customers, who further process it. It is then used to generate low-cost and environmentally friendly electricity, without producing greenhouse gases which are by-products of other fuels.

Deep Disposal Well

Waste water is generated from our precipitation process, as well as a small quantity from the Reverse Osmosis Unit. This waste is injected deep into the earth, below any usable ground water formations. Like all aspects of our operation, the disposal well is operated under license from regulatory agencies and is monitored by them. Unlike the disposal wells used by the chemical industry, our disposal wells are nonhazardous.

Disposal Well Records

Some waste liquids are pumped into a deep disposal well, as approved by license. The waste wells used in ISR are nonhazardous. This is different from wells used by the chemical industry for similar disposal, which are considered hazardous.

Records of disposal are permanently recorded on charts, such as the one shown here. These charts are used to verify that the well operated within the limits specified by regulatory agencies.

The Final Product

Our final product is yellowcake, a dry yellow powder, low in radioactivity. It must be enriched before it can be used to produce electricity.

Reclaimed Wellfield at Longoria

Once the operation is complete, the wellfield is restored and completely decommissioned. This was once the wellfield at our Longoria Plant.