Titanium was discovered in 1791, but the first pure titanium was produced in 1910, and it took more than a hundred years. The reason is: titanium is very active at high temperatures, and it is easy to combine with oxygen, nitrogen, carbon, and other elements. It needs very harsh conditions to extract pure titanium.
In industry, sulfuric acid is commonly used to decompose ilmenite to produce titanium dioxide, and then to produce titanium metal from titanium dioxide. Concentrated sulfuric acid treats ground ilmenite (concentrate), and the following chemical reactions occur:
FeTiO3+3H2SO4 == Ti(SO4)2+FeSO4+3H2O
FeTiO3+2H2SO4 == TiOSO4+FeSO4+2H2O
FeO+H2SO4 == FeSO4+H2O
Fe2O3+3H2SO4 == Fe2(SO4)3+3H2O
In order to remove impurity Fe2(SO4)3, iron filings are added, Fe3+ is reduced to Fe2+, and then the solution is cooled to below 273K so that FeSO4·7H2O (green vitriol) crystallizes out as a by-product.
Ti(SO4)2 and TiOSO4 are separated into white metatitanic acid precipitation by water, and the reaction is:
Ti(SO4)2+H2O == TiOSO4+H2SO4
TiOSO4+2H2O == H2TiO3+H2SO4
Titanium dioxide is obtained by calcining metatitanic acid:
H2TiO3 == TiO2+H2O
Titanium metal is produced industrially by the metallothermic reduction method to reduce titanium tetrachloride. Mix and heat TiO2 (or natural rutile) and carbon powder to 1000-1100K for chlorination treatment, and condense the generated TiCl4 vapor.
TiO2+2C+2Cl2=TiCl4+2CO-
Reduction of TiCl4 with molten magnesium in argon at 1070K yields a porous titanium sponge:
TiCl4+2Mg=2MgC12+Ti
This sponge titanium is crushed, melted in a vacuum electric arc furnace, and finally made into various titanium materials.
It can also be reacted: Ti+2I2=TiI4
The obtained TiI4 is decomposed at a high temperature (about 1250 degrees Celsius):
TiI4=Ti+2I2
Thus a pure titanium rod is obtained.
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