Uranyl chloride
Encyclopedia
Uranyl chloride, UO2Cl2 is an unstable, bright yellow coloured chemical compound of uranium
. It forms large sand-like crystals which are highly soluble in water
, alcohol
s and ether
s. Uranyl chloride, and its two hydrate
s (UO2Cl2·H2O and UO2Cl2·3H2O) decomposes in the presence of light, a fact discovered by Adolph Gehlen in 1804, This photosensitivity periodically attracted scientific curiosity and various unsuccessful attempts to develop photographic
applications using the salts. As with most other uranic species this compound also exhibits fluorescence
.
Uranyl chloride is formed when chlorine
gas is passed over uranium dioxide
at a red heat. However it is more usually obtained by dissolving uranium oxide
in hydrochloric acid
and evaporating.
(IREL) has developed a process to extract uranium from the Western and Eastern coastal dune sands of India
. After pre-processing with high intensity magnetic separators and fine grinding, the mineral sand
s (known as monazite
), are digested with caustic soda at about 120C and water. The hydroxide concentrate is further digested with concentrated hydrochloric acid
to solubilise all hydroxides to form a feed solution composed of chlorides of uranium and other rare earth element
s including thorium
. The solution is subjected to solvent extraction with dual solvent systems to produce uranyl chloride and thorium oxalate. The crude uranyl chloride solution is subsequently refined to nuclear grade ammonium diuranate
by a purification process involving precipitation
and solvent extraction in a nitrate media.
and kidney
s. It is toxic to aquatic organisms, and may cause long-term adverse effects in the aquatic environment. As with all compounds of uranium it is radioactive to a degree dependent on its isotopic ratio
s.
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
. It forms large sand-like crystals which are highly soluble in water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
, alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
s and ether
Ether
Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...
s. Uranyl chloride, and its two hydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
s (UO2Cl2·H2O and UO2Cl2·3H2O) decomposes in the presence of light, a fact discovered by Adolph Gehlen in 1804, This photosensitivity periodically attracted scientific curiosity and various unsuccessful attempts to develop photographic
Photography
Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...
applications using the salts. As with most other uranic species this compound also exhibits fluorescence
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...
.
Uranyl chloride is formed when chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
gas is passed over uranium dioxide
Uranium dioxide
Uranium dioxide or uranium oxide , also known as urania or uranous oxide, is an oxide of uranium, and is a black, radioactive, crystalline powder that naturally occurs in the mineral uraninite. It is used in nuclear fuel rods in nuclear reactors. A mixture of uranium and plutonium dioxides is used...
at a red heat. However it is more usually obtained by dissolving uranium oxide
Uranium oxide
Uranium oxide is an oxide of the element uranium.The metal uranium forms several oxides:* Uranium dioxide or uranium oxide * Uranium trioxide or uranium oxide...
in hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
and evaporating.
Industrial importance
The company Indian Rare Earths LimitedIndian Rare Earths Limited
Indian Rare Earths Limited ' is a government-owned corporation in India based in Mumbai. It was incorporated as a private limited company and jointly owned by the Government of India and Government of Travancore Cochin. Government of India took control of IREL in 1963 under the administrative...
(IREL) has developed a process to extract uranium from the Western and Eastern coastal dune sands of India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
. After pre-processing with high intensity magnetic separators and fine grinding, the mineral sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
s (known as monazite
Monazite
Monazite is a reddish-brown phosphate mineral containing rare earth metals. It occurs usually in small isolated crystals. There are actually at least four different kinds of monazite, depending on relative elemental composition of the mineral:...
), are digested with caustic soda at about 120C and water. The hydroxide concentrate is further digested with concentrated hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
to solubilise all hydroxides to form a feed solution composed of chlorides of uranium and other rare earth element
Rare earth element
As defined by IUPAC, rare earth elements or rare earth metals are a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides plus scandium and yttrium...
s including thorium
Thorium
Thorium is a natural radioactive chemical element with the symbol Th and atomic number 90. It was discovered in 1828 and named after Thor, the Norse god of thunder....
. The solution is subjected to solvent extraction with dual solvent systems to produce uranyl chloride and thorium oxalate. The crude uranyl chloride solution is subsequently refined to nuclear grade ammonium diuranate
Ammonium diuranate
Ammonium diuranate or ' , is one of the intermediate chemical forms of uranium produced during yellowcake production. The name 'yellowcake' originally given to this bright yellow substance, now applies to mixtures of uranium oxides which are actually hardly ever yellow...
by a purification process involving precipitation
Precipitation (chemistry)
Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...
and solvent extraction in a nitrate media.
Health and environmental
Uranyl chloride is spectacularly toxic by inhalation and if swallowed. There is also a danger of cumulative effects. The target organs are the liverLiver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
and kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
s. It is toxic to aquatic organisms, and may cause long-term adverse effects in the aquatic environment. As with all compounds of uranium it is radioactive to a degree dependent on its isotopic ratio
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s.