minéraux et minerais jun. 2013 | Page 5

ALL ABOUT TITANIUM

Atomic number: 22

Atomic mass: 63.546 g.mol

Density: 4.507 g.cm

Melting point: 1668

Boiling point: 3287

Electron configuration: 2 8 10 2

Is a light, strong, white-metallic, lustrous, corrosion-resistant transition metal, titanium is used in strong lightweight alloys and in white pigments.

Titanium is a metallic element which is well known for it’s excellent corrosion resistant and for it’s high strength-to-weight ratio. It is light, strong, easily fabricated metal with low density that, when pure, is lustrous, and metallic-white.

Titanium is as strong as steel, but 45% lighter and 60% heavier than aluminum, but twice as strong.

Titanium is the only element that burns in nitrogen.

*Corrosion: The process of corroding (destroy or damage) metals, stone, or other materials.

Uses of Titanium:

Titanium is corrosion resistant, very strong and has a high melting point. It has a relatively low density (about 60% that of iron). It is also the tenth most commonly occurring element in the Earth's crust. That all means that titanium should be a really important metal for all sorts of engineering applications.

Titanium is very expensive and only used for rather specialised purposes.

Used for...

- In the aerospace industry: aircraft engines and airframes

- for replacement hip joints

-for pipes, etc, in the nuclear, oil and chemical industries where corrosion is likely to occur.

Extraction of Titanium

Titanium comes at about the same level as Aluminum in the reactivity series. Of the titanium ores only rutile (TiO2) and ilmenite (FeTiO3) have economic importances.

The metals react with oxygen at high temperatures it can’t be produced by reduction of it’s dioxide. Titanium metal is therefore produced commercially by the Kroll process.

Kroll process developed by William Justin Kroll in 1946:

• Concentrating - separation of titanium dioxide from the gangue (the commercially valueless material in which ore is found) and iron oxide (in ilmenite).

• Carbochlorination - chemical treatment of titanium dioxide in fluid bed reactor with chlorine and (petroleum) coke at the temperature 1650°F (900°C) resulted in formation of impure titanium tetrachloride:

TiO2 + Cl2 + C = TiCl4 + CO2

Further process:

Purification of the liquid impure titanium tetrachloride using fractional distillation and precipitation to remove iron chloride and other impurities.

Titanium sponge production – reaction of pure titanium tetrachloride with magnesium in a stainless retort at 2010°F (1100°C) under argon atmosphere:

TiCl4 + 2Mg = Ti + 2MgCl2

The resulted magnesium chloride is liquid and it is separated from the solid titanium which is obtained in form of porous sponge.