Congo’s Hidden Uranium Exports

The Katanga region in the southeast Democratic Republic of Congo has for decades been known as the Copper Belt. But in recent years, in addition to copper, its mines have become focused on the extraction of cobalt, a critical metal used to make lithium-ion batteries for electric vehicles and AI chips, as well as alloys for use in aerospace and other high-tech manufacturing industries.

Overwhelmingly, cobalt ores mined in Katanga are sent to China to be refined into the pure metal. Historically, there is also a third mineral in Katanga’s rich deposits – uranium. Much of the uranium acquired for the Manhattan Project came from the region’s Shinkolobwe mine. But exports of uranium from the DRC are supposed to be banned.

Lighthouse’s reporting on hidden exports of uranium from the DRC began with a leaked memo from the International Atomic Energy Agency that we obtained in 2024. The previously unreported document was dated 2009 and cited credible information indicating that uranium was present in “significant quantities” in most cobalt ore from Katanga. The uranium was “actually exported as a by-product of cobalt,” the memo stated.

Since that document was written, cobalt mining in the DRC has scaled up dramatically and those mines have overwhelmingly sent their ore to China. By 2023, China was responsible for refining 80 percent of the global supply of cobalt, with the vast majority of the ore coming from mines operated by Chinese companies in the DRC. According to recent estimates 95 percent of Congolese cobalt goes to China.

In September 2024, Lighthouse teamed up with Sébastien Philippe, now assistant professor of nuclear engineering at the University of Wisconsin-Madison, then a senior researcher at Princeton University’s Program on Science & Global Security, to ask how much uranium could be making its way to China in exports of cobalt ore.

If the situation described in the IAEA memo had continued unabated, uranium extracted from Congolese cobalt ore could be strategically significant to China. In the past decade, China’s nuclear weapons stockpile has doubled to around 600 warheads and is expected to reach 1,000 warheads by 2030, according to estimates from the Pentagon. China’s known imports and domestic production of uranium do not come close to accounting for the scale of this expansion. China’s Ministry of Defence has previously objected to US reports on the size of its nuclear arsenal and accusation of a non-transparent buildup.

METHODS

Confirming the previously unreported supply of Congolese uranium required a combination of rigorous scientific assessment of the potential supply chain and traditional reporting from human sources as well as any leaked documents they could provide.

Philippe was joined by Princeton postdoctoral researcher Ryan Manzuk, a geologist whose interests span from geochemical modelling to advanced remote sensing. He set upper and lower bounds for the amount of uranium exported from each mine from 2000 to 2024, based on prior analyses of the concentration of uranium ores at sites across the Katanga region, extrapolated to each mine by geochemical modelling. That involved a trip to Europe in January 2025 to gather data and consult with other experts — most importantly at the AfricaMuseum in Tervuren, Belgium, which holds a large collection of geological samples collected from Katanga.

As evidence of the scale of uranium distribution across the cobalt deposits became clearer, we focused on understanding whether the uranium was being separated from the cobalt ore at mines in the DRC. Our partners at the Financial Times provided input on ore production figures for each mine and scoured trade databases for data on the supply of chemicals — notably phosphoric acid — that would be required to extract uranium from cobalt ores before export.

The data on chemicals supplied to mines in the DRC aligned well with insights gained from source reporting with industry insiders and leaked documents on processes at key Katanga mines. This allowed Manzuk to account for the separation of uranium before export of cobalt ore at some mines, refining the model’s estimates for total unreported uranium exports.

While the chemicals trade data indicated that separation of uranium in the DRC was not happening at the required scale, Manzuk explored the cutting edge of remote sensing to examine the chemical composition of tailings piles and ponds—the waste materials and slurry left behind after initial processing of mined ore. We hoped this would reveal the presence or absence of attempts to separate uranium from cobalt ore at the mines.

In January 2025, we approached the company Planet Labs about data from its Tanager satellite, which delivers “hyperspectral” imagery with images containing 424 separate bands at different wavelengths. In theory, it should be possible to obtain from these images detailed spectra quantifying the presence of particular minerals in a mine tailings pile or ponds.

Planet provided images for several of our target mine sites but we were frustrated in this effort, for two main reasons.

First, we were interested in spectra reflecting from the Earth’s surface, while Tanager had so far focused on the upper atmosphere to detect plumes of methane leaking from oil and gas facilities. This means that Planet’s engineers had not yet operationalized methods to correct surface images for the scattering and absorption of light caused by water vapour, aerosols of microscopic particles, and other components of the atmosphere. Second, there was a shortage of reference spectra for uranium-rich minerals such as autunite that we wanted to detect, making any comparisons difficult.

Even without this analysis, the modeling work progressed well. A peer-reviewed paper authored by Manzuk and Philippe, now published in the academic journal Nature Communications, concludes that a range of between 2,000 and 5,000 tonnes of uranium were exported from the DRC to China in shipments of cobalt hydroxide ore between 2000 and 2024. Even on the lower end of the range, that is enough uranium to fuel a gigawatt nuclear reactor for a decade or more. Our reporting does not indicate whether and how this uranium has been used in China.

Despite the scientific case, much of the cobalt mining industry continues to deny that it has a problem with uranium in the DRC. On paper there are strict national and international limits on the safe parts per million (ppm) of uranium present in cobalt exports and measures in place to test for radioactivity. In practice there have been a number of contamination incidents throughout the supply chain.

Interviews with dozens of industry sources including mining executives, traders, apnd metallurgists, revealed the lack of systematic checks on uranium contamination in the cobalt ore. Collaborating with the Financial Times, we obtained trade data indicated that mining companies import phosphoric acid, used to remove uranium from ore, in large quantities only after major incidents where contaminated exports were flagged.

“It’s when you have an issue that you’re monitoring where the uranium is,” said a senior metallurgical engineer who worked in the Katanga region.

Some experts, including Doug Alexander, former head of metallurgy at the Eurasian Resources Group, a company that mines in Katanga, suggested that there were, in effect, two different supply chains: one where efforts were made to contain uranium contamination once it was flagged; and one where lower cobalt quality products with higher impurities, including uranium, were headed to China.

A stream of leaked documents and spreadsheets, coming from Tenke Fungurume Mining (TFM), one of the largest cobalt mines in the DRC, reinforced the conclusions from the scientific modelling. TFM was formerly owned by the US company Freeport-McMoRan, but acquired by the Chinese company CMOC in 2016.

Internal TFM memos and spreadsheets confirmed the production of cobalt samples rich in uranium, with the maximum level reaching 1,100 ppm in December 2016, or 15 times the level that should be allowed for export.

The documents described experiments in the removal of uranium from cobalt ore at TFM towards the end of its period under US ownership. But according to three informed sources, comprehensive removal was not implemented. Indeed, a second batch of leaked TFM documents we obtained confirmed that significant quantities of uranium were present in batches of cobalt ore from TFM as late as June 2021.

Other key documents came from STUK, the Finnish Radiation and Nuclear Safety Authority, describing the separation of uranium from shipments of cobalt at Freeport-McMoRan’s Kokkola refinery in Finland. One 2014 permit gave the refinery a 10-year authorisation to produce and hold uranium separated from cobalt ore as long as the quantity remained below 10,000 kilograms per calendar year — the level at which it would have become subject to safeguarding protocols for nuclear materials overseen by the IAEA.

Faced with the evidence gathered in the investigation, officials in the DRC told journalists we worked with at the Financial Times that uranium contamination of cobalt ores was a real concern, both from the perspective of the health of miners and those living near the mines, and for the safeguarding of nuclear materials.

Steve Muanza, the head of the DRC’s nuclear energy agency, said it is “technically possible” and even “likely” that Chinese companies are extracting uranium from cobalt ore exported from the DRC. He said his agency had requested funding to install radiation monitors for trucks leaving the DRC for Zambia along the DRC’s National Highway One.

In a nation riven by war and with a long and porous border, however, shutting down covert exports of uranium will be extremely challenging. Assessing the full extent of risks to the communities living near mine sites will also need urgent attention.

Responses from relevant companies:

Cmoc denied any uranium contamination of its cobalt ore. “There are no instances of uranium levels exceeding applicable limits,” the company said. Cmoc added that all the Tenke cobalt hydroxide “complies with local regulatory requirements” and that it is “not aware of the source of the historical data” used in this investigation.

Freeport Mc Moran, the previous owner of Tenke operation, declined to comment.

Umicore, the current owner of the Kokkola refinery in Finland, said in a statement that “uranium is treated as an incidental impurity, not as a co-product or value stream”, and that the company follows “strict regulatory and contractual acceptance criteria”. Both Orano and Glencore did not comment on our findings, when ERG said that the company follows “all applicable regulatory requirements” regarding uranium at its Metalkol mine.

China’s Ministry of Industry and Information Technology did not respond to a request for comment. In the past, China’s Ministry of Defense objected to American reports on the size of its nuclear arsenal, and recently accused the US of “peddling the narrative of China’s massive and non-transparent nuclear build-up”.

An IAEA expert said the agency believed that the DRC was meeting its safeguarding obligations and that most of the time, the uranium, contained in cobalt “ends up in the tailings” they added, referring to mining waste.

Read full response from relevant companies here.

CO-PUBLICATIONS

• Financial Times: DR Congo’s cobalt boom carries an unwanted cargo: uranium
• Nature Communications: Uranium in cobalt-hydroxide exports from the Democratic Republic of the Congo