How Uranium Mining Works


The Grand Canyon is gorgeous. It's also home to a whole lot of uranium, much of which is off-limits for at least 20 years, thanks to a U.S. ban enacted in 2012. See more nuclear power pictures.
Christer Fredriksson/Lonely Planet Images/Getty Images

Mining towns draw monikers from it. Political leaders keep close tabs on it. Others flat out disparage it.

Indeed, uranium owns its share of controversy.

For years, the element has been tied to talk of nuclear weapons and the birth of the atomic age. Today, however, the metal has taken on a different role -- in the form of energy. In fact, much of the enriched uranium stored in nuclear weapons from the arms race has been rededicated to fueling the world's nuclear power reactors, which provided the world with almost 14 percent of its electricity in 2010 [source: Nuclear Energy Institute].

And it's extremely powerful, too. One 7-gram pellet of uranium fuel produces as much energy as 3.5 barrels of oil and 807 kilograms (1,779 pounds) of coal [source: Newfoundland Labrador DNR].

Beyond lighting up homes and businesses through nuclear power, uranium makes radioisotopes that produce radiation, which can help diagnose and treat certain medical conditions. It's also used for shielding and, in its depleted form, as counterweights for aircraft, too.

But where does uranium come from and how is it gathered?

Like other metals, uranium occurs naturally in rocks on the Earth's surface and can be extracted through uranium mining. Miners originally discovered uranium alongside radium, another element that was used as glowing, decorative paint (at least until people realized its harmful, radioactive effects). Uranium hit the market as a decorative glaze before its nuclear properties were discovered.

This heavy metal comes in several isotopes, or forms of the element with different numbers of neutrons. Depending on the stability of an isotope, some can be more radioactive (likely to give off energetic particles) and fissile (likely to produce nuclear fission) than others. Uranium-238 measures as the most abundant isotope of the element on Earth and can be found in rocks and seawater. But it's not as radioactive as uranium-235, the best-known form of uranium used to create nuclear reactions.

In this article, we'll chart the uranium mining process, tracking the element as it transitions from ore to fuel pellets ready to be used by nuclear reactors. We'll also look at the wax and wane of uranium mining, as well as the risks for humans and the environment by following the contentious debate over mining uranium in the backyard of the U.S.'s most iconic canyon.

Dust off your doomsday clock as we revisit the origins of uranium mining and all things nuclear on the next page.

History of Uranium Mining: Race for the Yellowcake

July 1, 1947: Miners search for uranium in the mountains north of Adelaide, Australia.
July 1, 1947: Miners search for uranium in the mountains north of Adelaide, Australia.
Hulton Archive/Getty Images

"Fat Man," "Little Boy," "The Bomb," "nukes" -- whatever may come to mind, atomic weapons became deeply ingrained into the global psyche after World War II.

Uranium's debut as a nuclear element dates back to the top-secret Manhattan Project, through which scientists developed the first atomic bomb. In the United States, mines popped up out West in the Colorado Plateau, an area that unites the corners of Utah, Colorado, New Mexico and Arizona. This period also coincides with the Atomic Energy Act of 1946, which allowed uranium mining in the United States as long as the finished product ended up in government hands [source: Atomic Energy Commission].

One of America's natural wonders, the Grand Canyon, has also served as a battleground for uranium mining in Arizona, where parties debated the area's importance for its natural resources and tourism [source: Amundson]. In fact, amateur prospectors picked up on radioactive areas that would later be named the Orphan Mine in Grand Canyon National Park.

Certainly, World War II put uranium in the position to be a powerhouse element.

"Uranium went from being a weed to a weapon," said Michael Amundson, a historian, professor and expert on the Atomic Age. "Instead of serving as this useless pigment, it became a strategic element of the war."

But North America wasn't the only continent with an appetite for uranium. Global demand for the metal grew in the 1950s during the arms race between the United States and the Soviet Union, when the highly enriched forms of the element were used to create atomic weapons. Around the world, economic incentives and the promise of defending one's country and its allies became reasons to support the conquest for the "wonder metal."

In the 1970s, the focus on uranium shifted to its use as fuel for the growing nuclear power sector. But the glamor and promise of atomic culture wore off as free markets became the norm. Public fears surrounding the nuclear technology also grew. The Three Mile Island accident in 1979 made people even more fearful of nuclear power and dealt another blow to already struggling uranium mining operations in the United States. Today, some experts say uranium mining is on the rise again, as the global demand for the element grows [sources: Nuclear Energy Agency; Deery].

So where does the hunt for uranium begin? Hint: Probably not in your backyard.

The Hunt for Uranium

Before companies can even think about putting miners on the job, they need to find ore deposits. How did novice prospectors, uranium boom opportunists such as Charlie Steen and seasoned experts find uranium to begin with?

Most mining sites stem from larger deposits, which vary in size and depth. Australia's Olympic Dam, one of the largest sites in the world, has explored and mined roughly 6.5 million feet (2,000 kilometers) of land [source: World Nuclear Association]. In recent years, surveyors have established that 1.1 million acres of land near the Grand Canyon may be suitable for mining, although U.S. President Obama announced a 20-year ban on uranium mining on 1 million acres of land near the Grand Canyon in 2012 [source: U.S. Natural Resources Committee].

This preliminary stage of the mining process is called exploration, where geoscience experts figure out which areas would be economically feasible to mine. Companies compare the estimated number of recoverable ore tons with the cost of extracting them. Because of financial constraints, landscape and access to a mining site dictate whether companies will invest in mining there. Even then, successes are rare. Among all minerals and metals, around one in every 1,000 exploration projects transitions into the mining stage [source: British Columbia Crown Land Administration Division].

But uranium's radioactivity makes finding it a bit easier. Geiger counters and scintillometers pick up on radiation and help survey uranium hot spots [source: Hunter]. Surveyors use hand-held Geiger counters to detect radioactivity closer to the ground, while larger devices called scintillometers can pick up gamma rays at greater distances. Geologists will also sample the soil and rock to find out the ratios of uranium hidden beneath the ground's surface. Several uranium isotopes occur together, including U-234, U-235 and U-238. Methods to detect them usually don't discriminate which is more abundant in a sample, but some devices that pick up U-235 may become more widely used.

Uranium's decay process also gives rise to byproducts called daughter elements such as radium and radon, which are both radioactive as well. Surveyors measure radiation carefully to make sure they're not mistaking other elements for uranium.

Once a company knows it wants to give uranium mining a shot, it must apply for permits from the local and federal government. The process differs by country, but most permits ensure that companies uphold standards that help protect the health of miners, nearby communities and the environment. In the United States, obtaining permits for mining, getting investors onboard and conducting resource assessments can take anywhere between three and 10 years [sources: Deery; Hunter].

Now that we know a bit about uranium's history and exploration phase, let's dig into the details of mining. Read more on the next page.

Mining: Making the Most of Radioactive Caches

Pictured is an open-pit uranium mine in Gas Hills, Wyo., March 1978.
Pictured is an open-pit uranium mine in Gas Hills, Wyo., March 1978.
Photo courtesy DOE

After locating uranium deposits and obtaining appropriate permits, a company will begin to mine. There are a few ways to extract uranium from the ground: open-pit mining, underground mining and in-situ recovery.

Mining methods depend on the type of deposit, whether it's suspended in water and the geography of the area. For instance, if miners find a deposit sandwiched between layers of rock and water, in-situ recovery will be a more cost-effective option. If experts deal with dry ore, they'll most likely stick with a type of open-pit or underground mining.

  • Open-pit removal for uranium closely resembles what's done to mine other metal ore. Experts and miners will use machines and explosives to create a pit. Then, they'll remove the uranium ore in chunks to be transported for further processing. Miners are specially trained to separate ore from waste. Often, they keep this motto in mind: "A mine is a terrible thing to waste, and waste is a terrible thing to mine" [source: Hunter]. Open-pit differs from other types of surface mining, which remove topsoil in strips throughout the mining process.
  • Underground mining calls for venturing deeper into underground mine systems, where miners use shafts or adits (vertical and horizontal tunnels) to move equipment and position workers throughout the mine. As we'll discuss later, mining underground for uranium poses higher health risks than other methods.
  • In-situ recovery (previously called in-situ leaching) remains a popular way to mine for uranium, especially in the United States, where uranium deposits often lie between rock and aquifers. Rather than removing chunks of ore for processing, in-situ recovery requires using chemistry to separate the uranium from ore in the ground. By injecting baking soda and club-soda-like solutions into the ore through pipes, miners separate uranium from the rock and pump the solution to the surface. In the United States, this is the most common form of uranium mining for sandstone deposits [source: EPA]. Experts say in-situ recovery leaves a smaller footprint on the environment, as well as a smaller reclamation tab for mining companies [sources: Deery; Hunter].
  • Some operations use heap leaching, a process by which companies extract ore, break it into smaller pieces above ground and leach the pile with chemicals to separate the uranium. As the chemicals soak in, the uranium leaches into underground pipes that gather the solution. American uranium mines do not practice this method, mostly because of the environmental impacts of using acidic chemicals.

Uranium mines might appear expansive, but a relatively small number of workers perform duties at each site. Roughly 35 people help drill and place steel reinforcements into the ground to secure shafts with machines, 35 miners specialize in removing the uranium ore (in open-pit operations; 20 for underground) and about 25 individuals assist with the reclamation process in efforts to restore land back to its natural state [source: Deery].

Head over to the following page to find out how a slushy mixture of rock and uranium becomes nuclear fuel.

Milling and Processing

At the mill, uranium ore undergoes a variety of changes to turn it into a finished product: uranium powder, also known as yellowcake.

The milling process is so important that the U.S. Atomic Energy Commission has helped mines establish mills close by to make it easier to process uranium ore and quicken the production of yellowcake [source: Amundson].

For dry uranium ore, the rocks are milled up into smaller pieces before being placed in tanks. In-situ recovery solutions are usually ready to be placed in tanks as well. Depending on how the uranium was mined, chemical solutions are applied to the ore to strip other substances away. One part of the process will separate sand and debris gathered with the ore through ion technology, while another will use a series of solvents to pick the uranium away from other parts of the ore. Throughout the milling process, remnants of other rocks and radioactive elements from the ore -- also called tailings -- are gathered to be stored away. The product will continue to undergo chemical separation until all that's left is the desired amount of uranium.

The goal is to isolate uranium oxide (U3O8) to sell to companies for further enrichment. Most milling operations employ between 20 and 50 people [source: Hunter].

After milling, other companies will buy the uranium to enrich it, or increase the ratio of the isotope U-235 in a given sample. During enrichment, scientists convert the yellowcake (uranium oxide) to uranium hexafluoride gas, which is put in cylinders to become a solid when it cools [source: NRC]. To enrich uranium enough to be used as nuclear fuel, workers will increase the concentration of U-235 in the sample to usually between 2 and 5 percent [source: Nuclear Energy Institute]. Then, fuel fabricators will transform the substance into uranium oxide powder to be compressed into uranium fuel pellets. The enriching process is highly regulated and is often done by companies other than the ones that mined it.

The effects of uranium mining span beyond the mine. Learn more about the activity's impact on human health next.

A Dangerous Metal? Uranium's Health Concerns

Ever since the negative health effects surrounding uranium mining began to surface in the 1950s, public opinion about uranium mines has split into camps of support and opposition.

Both sides agree that uranium mining raises legitimate health concerns. The most dangerous aspects of uranium mining involve radon gas, radiation and toxicity hazards.

Radon gas, a direct product of radium-226, which stems from uranium-238 decay, is known to cause lung cancer [source: New Hampshire Department of Environmental Services]. Although radon may frequent all types of mines, tobacco smokers have an increased risk of developing cancer [sources: Nuclear Energy Institute; Hunter] About halfway through the 20th century, mining regulations tightened to make conditions safer. Mines now require complex ventilation systems and protective gear for miners working in conditions with radon, especially for underground mining projects. Work areas, including break rooms and small buildings on-site, are routinely tested for radon gas in the United States.

There's also the problem of ionizing radiation, which is caused more by the elements commonly found with uranium such as radium. Some radiation can travel through skin, but the type involved with extracting uranium causes the most problems when it's accidentally ingested or inhaled. Several studies have linked these radioactive elements to an increased risk of cancer [source: New Hampshire Department of Environmental Services].

Uranium itself poses more risk as a toxic substance than a radioactive element. Ingesting uranium can cause kidney problems [source: Argonne National Laboratory]. Its radioactive cousin, radium, often integrates itself into a person's bones, which can degrade a person's health and even cause death. Because of certain risks, physical demands and skills involved in all types of mining, individuals working in this industry make salaries that are usually higher than the national average [sources: Deery; Hunter]. In 2010, U.S. miners, including those who mine for uranium, made $67,000 on average -- more than $20,000 more than other U.S. workers [source: National Mining Association].

For nearby communities, the largest health risk may be contaminated drinking water from mining, which can contain radioactive particles and heavy metals. One expert estimates that it normally takes around 40 years to remediate groundwater from mining sites back to safe levels [source: Deery].

Uranium mining's effects aren't limited to humans. Next, we'll look at uranium mining's impact on the environment.

Uranium Mining: Hazards for the Environment

As you can imagine, uranium mining requires physically manipulating the ground in some way.

So how do companies and governments ensure mining practices don't negatively affect local ecosystems and wildlife? How do businesses and citizens share public land, especially if it's a natural landmark such as the Grand Canyon?

The environmental effects of uranium mining remain a controversial talking point. Tailings, which are leftover pieces of ore and byproducts from mills, can contain radon, radium, thorium, polonium and sometimes arsenic.

Perhaps the most serious concern is water quality. U.S. mines abandoned before the mid-1970s are deemed the most dangerous because tailings were left on site and were never properly disposed of [source: EPA]. There's also the risk of toxic and radioactive material being carried by rain and wind.

Both the mining process and abandoned mines have had negative effects on the health and land quality of nearby communities, particularly throughout Navajo lands in the United States [sources: Frosch; Amundson].

Balancing human and environmental interests lies at the heart of the uranium mining debate. On average, uranium mining sites last roughly 30 years, providing locals with jobs and economic opportunity. Individual mines last approximately seven years before becoming depleted [source: Deery].

The short-term economic benefits of mining for small towns become apparent as well.

"It brings 35 and 40 people into town with above average salaries," said Rick Deery, a geologist and mining law leader at the U.S. Bureau of Land Management. "They're going to buy stuff ... they're going to support indirect jobs."

Other people don't think the long-term effects on the environment justify uranium mining, while supporters of the practice say uranium represents a cleaner form of energy than coal or oil [source: Hunter].

Still, tighter regulations and Superfund projects have sought to clean up uranium mines. Companies usually commit to reclamation bonds, or a type of collateral that ensures enough money will be put toward to cleanup efforts after the mining process ends [source: Office of Service Mining Reclamation and Enforcement]. Remediation typically involves cleaning up waste from a site, while reclamation seeks to restore the area back to its natural state.

Violating land management rules established by the government can result in a hefty fine -- upward of $200,000. "For the most part, the mining industry has got too much invested in these operations to screw up," said Deery " ... If they get put out of business, nobody's ever going to hire them again."

Prospectors and novices alike: Check out the resources on the next page for more on uranium mining.

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More Great Links

Sources

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