Uranyl chloride refers to

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

s with the formula UO₂Cl₂(H₂O)_n where n = 0, 1, or 3. These are yellow-colored solids.

Synthesis and structures

The hydrates are obtained by dissolving

uranyl sulfate Uranyl sulfate describes a family of inorganic compounds with the formula UO2SO4(H2O)n. These salts consist of sulfate, the uranyl ion, and water. They are lemon-yellow solids. Uranyl sulfates are intermediates in some extraction methods used for ...

uranyl acetate Uranyl acetate is the acetate salt of uranium oxide, a toxic yellow-green powder useful in certain laboratory tests. Structurally, it is a coordination polymer with formula UO2(CH3CO2)2(H2O)·H2O. Structure In the polymer, uranyl (UO22+) ...

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

followed by crystallization from concentrated solutions. Depending on the method of drying, one obtains the mono- or the trihydrate. The monohydrate is described as a yellow, sulfur-like powder. It is very hygroscopic. The trihydrate is greenish-yellow. Both hydrates are fluorescent solids that are highly soluble in water. The anhydrous material can be obtained by the reaction of oxygen with

uranium tetrachloride Uranium tetrachloride is an inorganic compound, a salt of uranium and chlorine, with the formula UCl4. It is a hygroscopic olive-green solid. It was used in the electromagnetic isotope separation (EMIS) process of uranium enrichment. It is one o ...

: :UCl₄ + O₂ → UO₂Cl₂ + Cl₂ In terms of structures, all three of these compounds feature the

uranyl The uranyl ion is an oxycation of uranium in the oxidation state +6, with the chemical formula . It has a linear structure with short U–O bonds, indicative of the presence of multiple bonds between uranium and oxygen. Four or more ligands may ...

center (''trans''-UO₂²⁺) bound to five additional ligands, which can include (bridging) chloride, water, or another uranyl oxygen.

Reactions

The

aquo ligand In chemistry, metal aquo complexes are coordination compounds containing metal ions with only water as a ligand. These complexes are the predominant species in aqueous solutions of many metal salts, such as metal nitrates, sulfates, and perchlorat ...

s can be replaced by a variety of donors, e.g. THF.

Industrial importance

The company

Indian Rare Earths Limited IREL (India) Limited (Formally Indian Rare Earths Limited) is a government-owned corporation Mini-Ratna Category A, Schedule B Company, in India based in Mumbai, Maharashtra. It was incorporated as a public limited company in 1950, jointly own ...

(IREL) has developed a process to extract uranium from the Western and Eastern coastal dune sands of

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. After pre-processing with high-intensity magnetic separators and fine grinding, the mineral

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...

s (known as

monazite Monazite is a primarily reddish-brown phosphate mineral that contains rare-earth elements. Due to variability in composition, monazite is considered a group of minerals. The most common species of the group is monazite-(Ce), that is, the cerium- ...

), are digested with

caustic soda Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alka ...

at about and water. The hydroxide concentrate is further digested with concentrated

to solubilise all hydroxides to form a feed solution composed of chlorides of uranium and other

rare earth element The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides (yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous silv ...

s including

thorium Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high me ...

. The solution is subjected to

liquid–liquid extraction Liquid–liquid extraction (LLE), also known as solvent extraction and partitioning, is a method to separate compounds or metal complexes, based on their relative solubilities in two different immiscible liquids, usually water (polar) and an org ...

with dual solvent systems to produce uranyl chloride and

thorium oxalate Thorium oxalate is the inorganic compound with the formula Th(C2O4)2(H2O)4. It is a white insoluble solid prepared by the reaction of thorium(IV) salts with an oxalic acid. The material is a coordination polymer. Each Th(IV) center is bound t ...

. The crude uranyl chloride solution is subsequently refined to nuclear grade ammonium diuranate by a purification process involving

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...

and

solvent extraction A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

in a nitrate media.

References

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External links

* {{DEFAULTSORT:Uranyl Chloride Uranyl compounds Chlorides Metal halides Oxychlorides