Uranium is extracted from the earth using three primary methods: in-situ leaching (also called solution mining), open-pit mining, and underground mining. In-situ leaching accounted for nearly 60% of global uranium production in 2022, followed by underground mining at 18% and open-pit mining at 16%. The method chosen depends on how deep the ore is, how concentrated it is, and the geology of the surrounding rock.
Finding Uranium Deposits
Before any mining begins, geologists need to locate uranium-bearing rock. Uranium exploration relies heavily on detecting natural radiation. Airborne surveys fly aircraft equipped with gamma-ray detectors over large areas to identify zones with elevated radioactivity. These detectors use scintillation crystals, typically sodium iodide or cesium iodide, that flash with light when struck by gamma rays. The flashes are counted and mapped to highlight promising zones below.
Once airborne surveys narrow down a target area, ground-based teams move in. They drill boreholes and lower probes into them to measure natural gamma-ray activity, magnetic susceptibility, and other properties of the surrounding rock. Scintillation detectors and Geiger-Müller counters are the two standard sensor types used in borehole logging. These readings help geologists estimate the grade and extent of a deposit, which determines whether mining is economically viable and which extraction method makes sense.
In-Situ Leaching: The Dominant Method
In-situ leaching, sometimes called in-situ recovery (ISR), works by dissolving uranium directly out of the ground without removing the rock. It’s the most widely used technique worldwide and the only method used in Kazakhstan, the largest uranium-producing country at 43% of global output. Uzbekistan, the fifth-largest producer, also relies exclusively on this approach.
The process works like this: wells are drilled into the ore body, and a solution (called lixiviant) is injected through some wells and pumped back up through others. In Kazakhstan, the solution is water mixed with sulfuric acid, which dissolves the uranium as it passes through the porous rock. In other countries, an alkaline solution using oxygen and bicarbonate is more common. The uranium-rich liquid that comes back to the surface is sent to a processing plant, where the uranium is separated out and dried into a concentrate called yellowcake.
ISR only works where the geology cooperates. The uranium deposit needs to sit in a porous layer of sandstone or similar rock, sandwiched between impermeable layers above and below that prevent the leaching solution from migrating away. If those conditions aren’t met, conventional mining is the only option.
Open-Pit Mining
When uranium ore sits close to the surface, open-pit mining is the most practical approach. This involves stripping away layers of soil and rock (called overburden) to expose the ore body, then extracting the ore with conventional heavy equipment: excavators, haul trucks, and loaders. Namibia, the world’s third-largest uranium producer, relies primarily on this method. Its Husab mine is one of the largest open-pit uranium operations in the world.
The extracted ore is crushed and then processed at a mill, where it’s dissolved in acid or alkaline solutions to separate the uranium from the surrounding rock. What remains after milling is a sandy, radioactive waste material called tailings. These tailings still contain most of the original radioactivity of the ore, primarily from decay products like radium and thorium, so their long-term containment is a major part of any mining operation.
Underground Mining
For deeper deposits, underground mining is necessary. Canada, the world’s second-largest uranium producer, uses this method at its major mines. The McArthur River mine extracts ore using a technique called raise bore mining, where a rotating cutter head drills upward from one tunnel level to another, and the broken rock falls down for collection. The Cigar Lake mine uses an innovative jet bore method that mines the ore remotely with high-pressure water, minimizing the time workers spend near the highly radioactive ore. In both cases, concrete is pumped in as backfill to stabilize the mined-out spaces.
Australia’s Olympic Dam mine is another major underground operation, though uranium there is actually a byproduct of copper mining. The ore contains copper, gold, silver, and uranium together, all extracted from the same rock.
Processing Ore Into Yellowcake
Ore from open-pit and underground mines goes through a milling process to extract the uranium. The rock is first crushed into small pieces, then ground into a fine slurry. This slurry is mixed with sulfuric acid (or sometimes an alkaline solution) to dissolve the uranium out of the rock. The dissolved uranium is then concentrated through a series of chemical separation steps and precipitated into a solid. After drying, the result is yellowcake, a uranium oxide powder that typically contains about 80% uranium by weight. Yellowcake is packed into drums and shipped to conversion and enrichment facilities for further processing before it can be used as nuclear fuel.
Managing Radioactive Waste
The tailings left over from milling are the biggest environmental challenge in uranium mining. They contain long-lived radioactive elements and must be isolated for centuries. According to the U.S. Nuclear Regulatory Commission, tailings are placed in large piles, often in lined trenches or former mine pits. New storage sites are typically lined, covered, and monitored for leaks.
The design of a tailings pile must be submitted for regulatory review as part of the mining license application. Operators are required to set aside funds for decommissioning the site, properly closing the tailings pile, and maintaining long-term monitoring. Once a site meets cleanup standards and the tailings pile meets approved design criteria, the license can be terminated and the site transfers to the Department of Energy for ongoing surveillance and maintenance under a general license. This process can stretch decades beyond the end of active mining.
Radiation Safety for Workers
Uranium mining exposes workers to radiation, and the international dose limit is 20 millisieverts per year, averaged over five years. For context, the average person absorbs about 2 to 3 millisieverts annually from natural background radiation, so miners are permitted roughly seven to ten times that baseline.
The biggest radiation hazard, particularly in underground mines, is radon gas. Radon is a naturally occurring radioactive gas released as uranium decays in the rock. For underground miners, inhaling radon and its decay products accounts for about 69% of their total radiation dose. For open-pit miners working in ventilated outdoor conditions, radon drops to about 34% of total exposure. Ventilation systems in underground mines are designed to keep radon concentrations low by continuously pushing fresh air through the tunnels and work areas. Dust suppression, protective equipment, and regular monitoring of both air quality and individual worker doses are standard across the industry.
Where Uranium Is Mined Today
In 2022, 17 countries produced uranium, with a global total of about 49,490 metric tons. The industry is highly concentrated. Kazakhstan alone produced 43% of the world total, more than Canada, Namibia, Australia, and Uzbekistan combined. Those top five countries, plus Russia, Niger, China, and India, accounted for 99% of global production.
Each major producer favors different methods based on local geology. Kazakhstan and Uzbekistan use exclusively in-situ leaching. Canada relies on specialized underground techniques suited to its extremely high-grade deposits. Namibia mines primarily from open pits. Australia uses a mix of underground mining and in-situ recovery, depending on the deposit. This geographic and technical diversity means that disruptions in one country or with one mining method can significantly shift global supply dynamics.