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. 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.
Summary of the conversion of titanium ore into useful products d Processing of titanium sponge 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.
An arc forms between the crucible and the electrode, causing the electrode to melt into the crucible where it is cooled and forms a large ingot. This may be repeated to produce a "second melt" ingot of higher quality. Titanium is corrosion resistant, very strong and has a high melting point. 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 because it is awkward to extract from its ores - for example, from rutile, TiO 2. 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. Both of these would, of course, first have to be extracted from their ores by expensive processes.
That means that you first have to convert the oxide into the chloride. That in turn means that you have the expense of the chlorine as well as the energy costs of the conversion. In the production of iron, for example, there is a continuous flow through the Blast Furnace. Iron ore and coke and limestone are added to the top, and iron and slag removed from the bottom. This is a very efficient way of making something. With titanium, however, you make it one batch at a time.
Titanium IV chloride is heated with sodium or magnesium to produce titanium. The titanium is then separated from the waste products, and an entirely new reaction is set up in the same reactor. This is a slow and inefficient way of doing things. Note: If you follow the link at the top of the page, you will find that there is now a continuous flow method involving sodium, and even a method of producing titanium electrolytically. If this is the first set of questions you have done, please read the introductory page before you start.
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