About Uranium

Uranium, metal that many associate with radioactivity, nuclear energy and industry, is more present in our environment than one might think. Different types of rock in the Earth’s crust naturally contain uranium minerals, which are mainly solid and do not usually pose a significant risk to the environment. However, human activity, especially mining, and the effects of rainwater can alter these minerals in such a way that uranium becomes soluble and can spread in the environment. Due to its radioactivity and chemical properties, soluble uranium can be harmful to both human health and ecosystems. What makes uranium important to EPSE is that our method can effectively precipitate soluble uranium from various waste streams into a stable, solid waste that does not cause harm to the environment.

The use and significance of uranium in energy production

Most of the processed uranium is used for nuclear energy production: according to the World Nuclear Association, 10% of all electricity worldwide is produced by nuclear reactors, and the largest users of uranium resources include the United States, China, France, and Russia. For several years, the demand for uranium has exceeded production, and the amount is only growing (Goehring & Rozencwajg, 2023). The use of uranium in the energy industry can be seen as a double-edged sword, as it is classified as a non-renewable raw material, but at the same time it can significantly help reduce carbon dioxide emissions from the energy industry. For example, when compared to natural gas and coal, the carbon dioxide equivalent (CO₂e) emissions from nuclear energy production are only a fraction of those from fossil fuels (London School of Economics Grantham Research Institute, 2019).

Uranium deposits and production processes

Uranium processing consists of several stages: the process begins with identifying mineral deposits and assessing their profitability. Uranium can be mined as the main product of the mine or as a by-product of other metals, for example in copper, nickel, and gold mines (Committee on Uranium Mining in Virginia et al., 2011). If the uranium deposit assessment proves to be positive, the process of starting mining and enrichment operations will begin. The world’s largest uranium mines are located in Canada, Kazakhstan, and Australia (World Nuclear Association, 2023). Other major producing countries include Uzbekistan, South Africa, Namibia, Brazil, the USA, and China (NEA & IAEA 2025).

Uranium is recovered from soil by leaching. Uranium can be separated either from mined ore or using the In Situ Leaching (ISL) method, in which uranium is leached and less invasively recovered directly from the soil using boreholes (IAEA, 2000). The dissolved uranium is precipitated, washed, and dried, resulting in uranium concentrate, also known as “yellowcake” (Orano, 2018). The dried uranium concentrate is sent for further processing, after which it can be used for purposes such as nuclear fuel.

Hazardous waste as the downside of mining

From the active excavation and production phase to the point when the ore reserves have been exhausted, the mining industry generates significant amounts of hazardous waste, known as tailings. Tailings contain waste from various mining processes, such as residues from the leaching process (waste acid), as well as waste rock from excavated soil, which may contain other harmful heavy metals (Pohjolainen, 2017). Radioactivity poses a particular challenge in the mining industry for uranium-containing ores: a large proportion of the daughter nuclides in the radioactive decay series of uranium, which include, for example, radium-226, radon-222, polonium-210, and thorium-230, remain in the tailings after the uranium has been recovered, making it a dangerous source of radiation (Brennan et al., 2014).

There are many ways to treat tailings and mine wastewater: one of the most common being chemical precipitation, in which the pH level of the fraction is raised from acidic to neutral (Dinis et al., 2021). The precipitated material is disposed of in large tailings ponds, which, at the end of mining operations, are covered with protective material, landscaped, and put to suitable reuse in accordance with the legislation of different countries.

Mining legacy

Legislation governing emissions and operations in the mining and uranium industries is becoming increasingly stringent, but unfortunately there are still many shortcomings. Reported cases of radioactive particles spreading as a result of poor closure management of mines have been observed in South Africa and Namibia (WISE Uranium Project, 2023 & Ihmig, 2023). Another well-known problem is the contaminated areas from the Soviet era, also known as “Uranium Legacy Sites”. According to a study conducted in Bishkek in 2009, a total of approximately one billion tons of waste from mining and the processing of radioactive ores has been stored in Central Asia in tailings areas at both operational and abandoned uranium mines.

Deficiencies in water and waste management in the mining industry as well as structural problems of tailings ponds pose a significant risk of environmental pollution. Since the 20th century, there have been reports of disasters around the world caused by negligence and natural conditions, in which radioactive and heavy metal-containing waste has been released into the environment as a result of tailings pond collapses (INARIS, 2022). Local people and nature are still paying a heavy price for these accidents decades later.

Soluble uranium and its effects to human and environmental health

Soluble uranium refers to uranium compounds that dissolve in water. In their soluble form, uranium compounds, like other heavy metals, can easily move around in the environment and be absorbed by living organisms, making them significantly more dangerous to health and the environment than insoluble forms (Keith et al, 2013). Exposure to soluble uranium can occur, for example, through contaminated drinking water or the food chain. The World Health Organization has set the maximum acceptable concentration of uranium in drinking water at 0.03 g/l. Exposure to uranium leads in particular to kidney dysfunction, but its effects and accumulation in the body can also lead to various liver, nervous system, reproductive, and bone damage (Keith et al., 2013).

Soluble uranium is found particularly in mining industry wastewater and uranium deposits, from which it can enter surrounding waterways via runoff, contaminating ecosystems for hundreds of years (Keith et al., 2013). Even small concentrations can poison fish, accumulate in the food chain, and cause deformities and reproductive problems in aquatic animals. In addition, the radioactivity of uranium compounds can accumulate in the kidneys, liver, and muscles, among other places (IAEA, 2018).

Risk elimination with the EPSE™ Method

EPSE’s solution for treating water containing uranium and heavy metals is not limited to producing clean water, but also takes into account the long-term storage of tailings waste from the mining industry. The re-solubility of the multi-metal sludge produced as the end product of the EPSE™ Method is very low. This means that the metals cannot redissolve during long-term storage or when conditions change, making the storage of the sludge safer.

Our goal is to create a zero-risk environment together with our partners by improving the quality of water treatment and developing digital solutions to ensure continuous monitoring of tailings ponds.

The article was written by Anna Kivimäki.

---

Sources in order of appearance: