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Uranium oxide is form of elemental uranium, a radioactive mineral found in nature. It appears as an oxide as a result of the mineral’s exposure to oxygen, often in the air but sometimes as a result of chemical manipulation in a laboratory. In its oxide form it is a rough powder with a crystalline structure, and it’s often black, grey, or yellowish-brown; a lot depends on the nature of the soil where it was mined and other environmental factors. It is sometimes also called uraninite, and is formally considered an “ore” of elemental uranium. It is the principal source for the commercial extraction of uranium, which has a number of uses as a fuel and also as an explosive. It 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.
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 element from the beads, creating a 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 oxide solution 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.
The compound can be further processed into enriched 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 its high density, 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 oxides can also be used as colorants in the glass and ceramic industries.
Raw uranium oxide is highly explosive as well as radioactive, which has traditionally made it useful as a component in certain bombs and other detonative devices. It is not always stable and great care must usually be used in handling it, which can make it a less attractive option than alternatives, many of which are more readily available today. During the Second World War, Nazi troops were alleged to have stockpiled the compound, apparently for use in atom bombs, and are also believed to have shipped vast quantities of the powder to their allies during this time.
Extensive exposure to any radioactive material poses certain health risks, and uranium and its ores are no exception. Breathing dust particulates and eating food that has come into contact with the oxide can cause a number of problems, the most immediate of which are breathing difficulties including lung collapse and organ failure. Scientists and researchers who regularly work with the substance are also usually encouraged to wear protective clothing and gear to avoid prolonged contact with the radioactive waves the chemical emits. The side effects of exposure aren’t usually immediate, but can include the development of advanced health problems including various cancers.
Uranium Oxide is bright yellow - uranium dioxide is black or brown.