How is titanium extracted

Geological Survey, Mineral Commodity Summaries, Titanium comprises 0. Titanium deposits that can be mined economically are found throughout the world. The main ores are rutile TiO 2 and ilmenite FeTiO 3 in beach sand deposits Western Australia , ilmenite-haematite Canada , and ilmenite-magnetite Ukraine in hard rock deposits Figure 5. Although rutile is scarcer and more expensive than ilmenite, it is more commonly used because it does not contain iron compounds and can therefore be more readily processed.

However, ilmenite is sometimes processed to remove the iron and make 'synthetic' rutile. Figure 5 Stockpiling heavy mineral concentrate which contains rutile, ilmenite and zircon, and other heavy minerals that are not valuable.

It will then be further processed to separate the rutile prior to beginning the process for the extraction of the titanium. By kind permission of Iluka Resources. Most titanium is manufactured from ores containing titanium dioxide using a lengthy four-stage process: a chlorination of the ore to titanium IV chloride b purification of titanium IV chloride c reduction of titanium IV chloride to titanium sponge d processing of titanium sponge.

Titanium dioxide is thermally stable and very resistant to chemical attack. It cannot be reduced using carbon, carbon monoxide or hydrogen, and reduction by more electropositive metals is incomplete.

If the oxide is converted into titanium IV chloride, however, a route to titanium becomes viable, as the chloride is more readily reduced. The dry ore is fed into a chlorinator together with coke forming a fluid bed. Once the bed has been preheated, the heat of reaction with chlorine is sufficient to maintain the temperature at K:.

The crude titanium IV chloride is purified by distillation, after chemical treatment with hydrogen sulfide or mineral oil to remove vanadium oxychloride, VOCl 3 , which boils at the same temperature as titanium IV chloride. Storage tanks must be totally dry as the product undergoes rapid hydrolysis in the presence of water, generating dense white fumes of hydrogen chloride:.

Titanium IV chloride is a volatile liquid. It is heated to produce a vapour which is passed into a stainless steel reactor containing molten magnesium in excess , preheated to about K in an atmosphere of argon.

Exothermic reactions giving titanium lll and titanium ll chlorides cause a rapid temperature rise to about K. These chlorides undergo reduction slowly, so the temperature is raised to K to complete the reduction process. Even so, it is a lengthy process:. After hours the reactor is removed from the furnace and allowed to cool for at least four days. In an alternative method, used in Japan, magnesium chloride, together with unreacted magnesium, is removed from the titanium by high temperature vacuum distillation.

The magnesium chloride is electrolysed to generate magnesium for the reduction stage and the chlorine is recycled for the ore chlorination stage. The titanium is purified by high temperature vacuum distillation. The metal is in the form of a porous granule which is called sponge.

This may be processed on site, or sold on to other companies for conversion to titanium products. Figure 6 Summary of the conversion of titanium ore into useful products. As titanium sponge reacts readily with nitrogen and oxygen at high temperatures, the sponge must be processed in a vacuum or an inert atmosphere such as argon.

At this stage scrap titanium may be included, and other metals may be added if a titanium alloy is required. A common method is to compress the materials together to create a large block which then becomes an electrode in an electric arc melting crucible. Note: Titanium IV chloride is a typical covalent chloride. It is a colourless liquid which fumes in moist air due to reaction with water to give titanium IV oxide and fumes of hydrogen chloride.

Everything has to be kept very dry to prevent this happening. TiCl 4 can be reduced using either magnesium or sodium. AQA will accept either, and so I am just giving the magnesium one. The reduction process is very slow, taking about 2 days, followed by several more days of cooling. When it is cool, the reaction mixture is crushed, and dilute hydrochloric acid is added to react with any excess magnesium to form more magnesium chloride. All the magnesium chloride dissolves in the water present, and the remaining titanium is processed further to purify it.

Titanium can't be extracted by reducing the ore using carbon as a cheap reducing agent. The problem is that titanium forms a carbide, TiC, if it is heated with carbon, so you don't get the pure metal that you need. The presence of the carbide makes the metal very brittle. That means that you have to use an alternative reducing agent. In the case of titanium, the reducing agent is either sodium or magnesium.

Workable deposits are found all over the planet, and yet it remains more expensive than any of those other metals. Extracting the Titanium Most titanium mining is done by open pit, meaning that the soil is taken from the ground and sent to factories where the ore can be removed. This process is usually done with a suction bucket wheel on a floating dredge. Mineral-rich sand is sent through its screens, called trammels, which starts filtering out the unwanted or unnecessary elements.

The separation is usually gravity powered, and the waste can be removed with a wet spiral concentrator. At this point, the separated material can be sent through some electrostatic, magnetic, and other gravity-fed equipment to further refine the materials into something useful. Processing the Material. So far, this process is not too far removed from other mining and extraction operations.