The chemistry of the process involves three main stages:ī) formation of hydrated titanium dioxideĬ) formation of anhydrous titanium dioxide (a) Dissolving the ore Table 1 Comparison of the two processes for the manufacture of titanium dioxide. Recovery and recycling of chlorine possible Small amounts of waste formed with toxicity problems: Cl 2 and TiCl 4 It is estimated that about 65% of the world's production is based on the Chloride Process. The Sulfate Process is run as a batch process the Chloride Process is run as a continuous process. Each produces the oxide in the rutile crystal form but the Sulfate Process can also produce another form of the oxide, anatase, which is softer and which is used for a small number of specialist applications. The ores are mined worldwide but most production is in Australia and South Africa.Įach large producer of titanium dioxide balances its production between the two processes. Ilmenite contains 45-60% TiO 2 and rutile contains up to 99% TiO 2. There are two main processes, the Sulfate Process and the Chloride Process (Table 1) which use the two principal ores, ilmenite and rutile, respectively. 2018 Elements of the Business of Chemistry, American Chemistry Council. Data for 2013, Merchant Research and Consulting, 2015Ģ. Annual production of titanium dioxide Worldġ.
It is also used to increase the acid resistance of vitreous enamels. The strong bonding between titanium and oxygen gives great thermal stability, melting at 2100 K. It also has a high dielectric constant and a high resistance and thus it is used to make capacitors. Much smaller amounts of titanium dioxide are used as a semi-conductor and to catalyse the photodecomposition of water into hydrogen and oxygen. It is also being used in novel nanotechnology applications.ĭata for 2013, Merchant Research and Consulting, 2015 It is resistant to UV radiation and thus does not discolour over a long period of time and ultra pure and fine crystal titanium dioxide grades are being increasingly used for sun screens. Titanium dioxide is the most used white pigment and provides whiteness and opacity for paints and coatings (including glazes), plastics and paper. It is these properties that underlie its most important uses. It is also a very stable compound and can be heated to over 2000 K before melting. Titanium dioxide has remarkable optical properties, with a very high refractive index close to that of diamond.