What Is Uranium Oxide?
Uranium oxide is a radioactive mineral made up of black, grey, or brown crystals that are generally opaque and have a greasy luster. It is also known as uraninite. This ore is the principle source for the commercial extraction of uranium, as it has a relatively high concentration of this element. Uraninite is usually mined from hydrothermal vein deposits and sedimentary rocks, such as sandstone, and can also be recovered as a by-product of gold and silver mining.
Uranium is a metallic chemical element that is weakly radioactive and has the highest atomic weight of all naturally occurring elements. It is approximately 70% more dense than lead, but has a lower density compared to gold. Uranium has a wide range of both military and civilian applications, most notably in nuclear technology due to its capacity to produce a sustained nuclear chain reaction.
Uranium ore is generally processed at its point of extraction into yellowcake, which can be transported for further processing. Yellowcake is often referred to as uranium oxide, but its complete name is uranium oxide concentrate, and it has the chemical formula U3O8. It is an insoluble yellow powder which contains approximately 80% of this oxide.
The first stage of processing involves grinding the uranium ore and adding water, until it reaches the consistency of mud. Ferric sulphate is used to oxidize the uranium ore, which is dissolved into sulphuric acid. This uranium-rich liquid is separated and placed in contact with special resin beads that absorb the uranium ions. An acid wash is used to removed the uranium from the beads, creating a uranium solution that is very concentrated.
An organic solvent is combined with the uranium solution, which is then mixed with ammonium sulphate. This leads to the precipitation of a substance known as ammonium diuranate, in essence a mix of uranium oxides and ammonia. The ammonium diuranate is then thickened and removed from the solution using rotating filters as a yellow paste. This paste is then roasted to remove any traces of ammonia, leaving behind uranium oxide.
Uranium oxide can be further processed into enriched uranium oxide fuel, which is sealed in the metal fuel rods that are fitted into nuclear reactors to produce the heat and steam required to generate electricity. A by-product of this enrichment process is depleted uranium oxide, which is no longer radioactive. Due to the high density of uranium oxide, once depleted it can be used in applications where large masses must fit in small spaces, such as helicopter counterweights and yacht keels, and is also used in the construction of radiation shielding, being much more effective than lead. Depleted uranium oxides can also be used as colorants in the glass and ceramic industries.
Written by Anne Morgan
