Symbol:Th
Melting point:1,755'C
Electronic Configuration:[Rn]6d27s2
Atomic number:90
Atomic Mass:232.03810.00002u
OreCommon NameFormula
PhosphateMonazite[Ca,La,Th]PO4

Thorium

Thorium is a rare earth element. Other important rare earth elements are Cerium, Yitrium, Gadolinium, Samarium and Neodymium. The uses of these elements vary from petroleum to metallurgical industries. These are also used in cathode ray and color television tubes. Some rare earth elements are also used in atomic reactors for production of atomic energy. Thorium is important as an alternative to uranium for use in the fast breeder reactors. The energy created is used for production of power. The major producers of rare earth minerals and metals are USA, China, Australia, Brazil, India, Canada and Malaysia.

Thorium is a metal related to titanium. Its specific gravity is 11. It is used as an alloying element. Thorium is radioactive in nature. Thorium compounds are used in medicines. Thorium is added as an alloying element to magnesium along with manganese and zirconium to produce light structural alloys. These are mostly used in aircraft wings and auto mobile body parts.

Extraction of Thorium

The monazite mineral contains 7 to 10 percent of thorium. The monazite mineral is reduced to metal concentrate in a rotary kiln in the presence of coal. The metal concentrate may contains impurities like cerium, manganese, nickel and phosphorous. These impurities may be separated from thorium by electrolysis. The monazite mineral concentrate is reduced and the metal concentrate is added to the melt of Sodium chloride and Potassium chloride. The cell is composed of a graphite crucible. The graphite crucible acts as anode. The cathode is of molybdenum rod. Purified argon gas is supplied into the bath. Potassium fluoride is added to help in precipitation of thorium. The temperature level is kept below 800 'C. The current is passed through the electrolyte. There is slow deposition of thorium on the cathode point. After the electrolysis is over the cathode is removed and leached in hot water and dilute hydrochloric acid. The precipitate is dried for further use.

Electrorefining of Thorium

Electro-refining of thorium is carried out by electrolysis of potassium and lithium chloride. Impure thorium metal forms the anode and molybdenum strips form the cathodes. After, electrolysis the pure thorium metal is deposited on the molybdenum strips. These are scrapped and removed for further use. The cell crucible is graphite. The purity of metal in this process of electro-refining is very high.