| Symbol: | U |
| Melting point: | 1,132'C |
| Electron configuration: | [Rn]5f36d17s2 |
| Atomic number: | 92 |
| Atomic mass: | 238.02891±0.00003u |
| Symbol: | Ra |
| Melting point: | 699.8'C |
| Electron configuration: | [Rn]7s2 |
| Atomic number: | 88 |
| Atomic mass: | 226 u |
| Ore | Common Name | Formula |
|---|---|---|
| Oxide | Pitchblende or Uraninite | UO2 |
| Hydrophosphates | Torbernite or Copper uranite | Cu[UO2][PO4]2,12H2O |
| Hydrophosphates | Autunite or Lime uranite | Ca[UO2]2[PO4]2,10-12 H2O |
| Hydrous vanadate | Carnotite | K2[UO2]2[VO4]2,3H2O |
| Hydrated sulphates | Zipperite | |
| Hydrated sulphates | Uraconite |
Uranium is a radioactive metal. It is white in color with a bluish tint. It has good lustre and takes high polish. It is very heavy, having a relative density of 18.7.
Pure uranium is malleable and ductile. It can be cast and fabricated by rolling or extrusion. It is chemically reactive and oxidizes at moderate temperature.
For atomic energy purposes uranium is melted in vacuum conditions in high frequency furnace. It is cast into 25 mm diameter rods. Metallic uranium is prepared by
reduction of its oxide with carbon in electric arc furnace. Uranium forms two oxides. From these oxides, complex group of uranium salts are prepared. Uranium oxides
and salts are used in glass staining, glazing, dyeing and in photography. It is mostly used in nuclear reactor for the production of plutonium. Plutonium is ultimately
used in nuclear reactor for production of power in nuclear based power plant.
Radium is another radioactive element found in association with uranium. It is used in treatment of cancer and x-ray machine. Its compounds are used in luminous paints.
The important minerals of uranium are pitchblende, torbernite, carnotite and autunite.
Major producers of Uranium are USA, Australia, Canada, South Africa, Namibia, Russia and China. Uranium is mostly used in nuclear energy production.
It is also used for production of special alloys. These alloys are used in gas discharge tubes. Uranium undergoes natural radioactive disintegration.
During disintegration, three types of radiation take place. These are alpha, beta, and gamma radiations. Due to continuous radiation, uranium gets transformed into
radium and ultimately to stable lead. By increasing the radiation faster, it is used in fast breeder reactor for production of plutonium. Plutonium is used in nuclear
reactor as nuclear fuel for production of power. It is also used for making atomic bombs and weapons.
Uranium can be extracted by electrolysis of uranium chloride and uranium fluoride. Two types of electrolysis processes are developed and followed for extraction of uranium.
a) Low Temperature Process
This process operates below the melting point of uranium. The melting temperature of uranium is 1132 'C.This method employs uranium chloride or uranium fluoride.
The anode is uranium or graphite. The cathode is of molybdenum metal.
Uranium chloride or fluoride is mixed with 80% calcium chloride and 20% sodium chloride.Maximum temperature may be 900' C. The cell is a graphite crucible. The process is started. The uranium is deposited on to the cathode. It may be removed from the cathode.
It may be removed from the cathode for further use. The solution is checked for its composition. More amount of uranium halides are added to the electrolytic solution.
In another method, uranium dichloride is electrolyzed in fused salt mixture of sodium chloride and potassium chloride.In some cases barium chloride is also added to the mixture.
Uranium dioxide is added to the fused chloride bath and the mixture is electrolyzed.
Chlorine gas is bubbled over the surface.
b) High temperature process
This process utilizes uranium oxide as a feed material. Uranium oxide is electrolyzed in a mixture of magnesium fluoride, barium fluoride
and uranium fluoride. This melt is an ideal choice because these fluorides are liquid at 1200'C.
Electrolysis is carried out in a graphite crucible. Graphite crucible serves as anode and uranium metal as cathode.
Electro refining of uranium used to be in small quantities. It produces pure uranium. The electrolysis is carried out at 400'C to 425'C under an atmosphere of argon and helium gas. Impure uranium serves as anode and cathode may be of molybdenum or tantalum. Electro refining is carried out on a small scale. It is carried out to avoid contamination of uranium and the left over electrolytes. Mostly the impurities are iron, copper, manganese, chromium and nickel.