Extraction of Titanium

It is a transition metal.

Member of group four in periodic table.

it’s atomic number is 22.

It’s mass number is 47.87

It has 5 stable isotopes with mas number 46-50 respectively.

It also has 4 unstable isotopes with mass number 43,44,45 and 51.

Introduction Of Titanium

It was discovered by William Gregor 1791 in England .

He recognized it to be present to ilmenite (FeTio3) from black sand due to its

non-magnetic nature.

It is derived from Greek word titans.

In 1795 a German chemist martin klaproth is discovered it from rutile named

it titanium after titans.

In 1910 hunter prepared metal by heating TiCl4 with sodium.

It is 0.6% of the earth’s crust.

It is 9th in order of abundance after oxygen and other 7 metals.

It’s main ores are rutile(TiO2), ilmenite(FeTio3) and sphene (CaTiSiO5).

History And Occurrence

It’s color is silvery metallic .

It is solid at room temperature.

Its M.P is (1668°C) and B.P is (3287°C).

Its density is 4.506g/cm3.

Strength of pure Ti decreases by 50% by increasing temperature up to 200°C.

It is light weight, corrosive resistant and can withstand at very high

temperature.

It is less resistant to corrosion in strongly reducing media.

Properties

Extraction

The main source of Ti extraction is rutile.

Rutile is converted into Ti by following processes:

1. Chloride process

2. Reduction with Carbon

3. Electro winning

Chloride process

In this process rutile is converted into TiCl₄

Calcined coke is used as reducing agent as it has low ash content

Because of low volatile contents of coke no HCl will found

TiO₂ + 2Cl₂ +C = TiCl₄ + CO₂

Because of the rise in temperature CO will form from CO₂ and carbon from

coke.

So we should introduce oxygen with Cl to maintain temperature at 800-

1200°C.

Coke consumption per ton of TiO₂ is 250 to 300 Kg

Production of titanium sponge

Crude TiCl₄

Preheating

Distillation <136°C SiCl₄,SnCl₄

H₂S, Cu Agitation and precipitation 90°C VOCl₂

Distillation >136°C FeCl₃,AlCl₃

Pure TiCl₄

Purification of TiCl₄

As the ore contains different impurities they either may be elements or

dust.

The elements form chlorides and are solid at room temperature.

These chlorides & dust are removed from TiCl₄ by distillation.

Some chlorides like VCl₄,VOCl₃ can not be removed by distillation as

they have close boiling points.

They are reduced to form solid low value VCl₄ & VOCl₃

Reducing agents may be Cu,H₂S, hydrocarbons & amines

In TiCl₄ there should be V less than 5 ppm

Oxidation of TiCl₄ TiO2 used in chloride process is not pure so we form TiCl₄ for its

purification.

Now we have to make TiO₂ again

So we oxidize TiCl₄

TiCl₄ + O₂ = TiO₂ + 2Cl₂

It is a weakly exothermic reaction, temperature of reaction should be high

Temperature > 1000°C can be achieved by heating O₂

Hot TiCl₄ & O₂ are fed into a reaction chamber separately

They must be mixed rapidly & completely to give a high reaction rate

The Cl can be removed either by liquefaction or by flushing N₂ or air

Reduction of TiO₂:

The reduction of titanium dioxide by carbon is only possible above 6000°c.

A complete reduction of titanium dioxide is only possible with alkaline

earth metal.

By dissolution of excess ca and cao in Hcl at 600-1200°C in a vacuum o

content of 0.1-0.3% in Ti is obtained.

Reduction with CaH₂ at 600-700°C gives TiH₂, which decompose at 900°C

in to Ti and H₂.

Reduction of Ticl₄(Kroll process):

Reduction is as

TiCl₄+2Mg Ti+2MgCl₂

It is discovered by Kroll.

Mg boil at 1120°C and MgCl₂ melts at 711°C the resulting temperature range and

the high purity of Mg are advantages.

The reactor constructed of plain c steel and (Cr- Ni) steel and interior was clean

by brushing or a (Ti) coated.

The reactor is charged with oxide free lumps of Mg and filled with (Ar) and (Mg) is

melted at 651°C.

Continued

When temperature reaches 700°C, purified TiCl₄ is run in slowly

form above or blown in as a vapour, such that a reaction

temperature of 850-950°C.

The Ti sponge is deposited in the reactor walls and form the solid

cake above the molten Mg.

The molten MgCl₂ collects beneath Mg and is drown of.

The Mg raises through the pours cake to it surface by capillary

action and reacts their gaseous TiCl₄.

Continued

Temperature must not exceed 1025°C to prevent the reaction between Ti

and Fe of reactor.

The amount of Ticl₄ reacted are 10-50% as some of Mg and Mgcl₂ in the Ti

sponge .

Excess of Ticl₄ leads to the formation of lower Ti chlorides and FE

chloride.

Generally temp ranges 850-950°C the lower temp give large reaction

time and pure sponge.

And removing Mgcl₂ and when temp falls to 200°C the vessel is opened in

dry room because Mgcl₂ and Ticl₄ are hygroscopic.

Crude sponge is purified by vacuum distillation and rarely leaching is used.

Leaching solution is H₂o Hcl and HNO₃.

Thermal decomposition of Ti halide:

The old process of VAN Arkel and DEBORE in which TiI₄ is decomposed on

electrically heated tungsten wise at 1000˚C.

If wires of single Ti are used then high purity can be obtained.

Librated I₂ reacted with corrode Ti to regenerate TiI₄.In same vessel

below 200˚C Over above 500˚Cabove 200˚C

Lower Ti iodized are formed witch only act as Ti carries above 500c

because of low volatility. Highest purity Ti is produced by crud Ti or Ti

scrap.

Continued

Very high purity Ti there also be obtained by thermal disproportionation

of Ti chloride and bromide.

by passing TaCl₄ vapor over Ti containing material at 950-1500˚C

Ti chloride is formed.

Ticl₂ vapor is condensed and is decomposed at 100O˚C

2TiCl₂ Ti+TiCl₄

TiCl₄ is fed back to the process .

Electro wining

High affinity of Ti for O₂ and H₂ prevents its deposition from aqueous

solution hence molten salt electrolyses can be used .

Only halides are suitable for electrolyses Ti tetraflouride combine with

alkali metal and alkaline earth metal fluoride to form complex hexafloro

titanates and these compound decomposed below there melting point

with the removal Ti tetrachloride .

These compound can be used in molten salt electrolyses as a component

of molten salt bath .

We add oxide to salt bath, oxygen pick up by the titanium metal must be

prevented by using low temperature by separating the anode to cathode

and by turbulence in electrolyte.

Processing of scrap metal

For mass production of Ti , Ti scrap should be used

This scrap is produced during the production of semi finished products, their

processing to finish products

This scrap may be mixed with sponge & compressed.

It may also be welded with sponge.

This scrap can also be added to the melt in small pieces along with sponge.

The scrap may also be used to produce Ti instead of mixing it with Ti sponge.

Untreated scrap can be added to steel, Ni, Al, Cu & Zn alloys.

Uses

Titanium alloys are used in aircraft.

These are also being used in naval ships, space crafts & missiles.

In steel alloys to reduce grain size and as a deoxidizer.

In stainless steel to reduce carbon content.

Because it is considered to be physiologically inert, the metal is used in joint

replacement implants such as hip ball.

Uses

Since titanium is non-ferromagnetic, it is used for long term implants & surgical

instruments for use in image-guided surgery.

95% of titanium is consumed for the production of TiO₂ which is used in paint, rubber,

paper and many other materials.

TiO₂ is also used heat exchangers, airplane motors, bone pins and other things requiring

light weight metals or metals that resist corrosion or high temperatures.

Due to excellent resistance to sea water, TiO₂ is used to make propeller shafts.