This is the process by which
Titanium is extracted from its ore (usually
Rutile). The process was first performed by Kroll in
Luxembourg, in 1937.
Essentially TiCL4 is reacted with molten Magnesium in Argon.
A Briquette of TiO2, coal, tar and Chlorinate are heated to 800 degrees C. This gives the following reaction:-
TiO2 + 2Cl2 + 2C -> TiCl4 +2CO2
This is then fractionally distilled, to give TiCl4 on its own. The TiCl4 is then reduced by molten Magnesium or Sodium in Argon, to prevent oxidation of the Ti.
TiCl4 + 2Mg -> Ti +2MgCl2
The titanium above forms as a sponge around the walls of the reaction vessel and needs to be periodically removed. This must then be purified using HCl to drive off the MgCl2. Note, if Na is used, the leaching is more efficient and a granular material is formed, which is more useful.
The Titanium metal is then heated in a Copper crucible, which is cooled by Water to prevent melting. The heat is generated by a direct current arc between a Titanium electrode and a starting piece of material. The whole vessel is evacuated of air and Argon gas is introduced.