Hydrolysis of titanium tetrachloride with water vapor at 25-75 C in air leads to the formation of a viscous liquid, solidifying the Slow the white mass. Vapor phase hydrolysis at 1000-1200 C produces titanium dioxide pigment properties, so it can be use, subject to finding an effective method of recycling the hydrogen chloride. Burning of titanium tetrachloride with oxygen flows through the reaction: TiCl4 + O2 = TiO2 + 2S12. Liberated chlorine can be returned to production for titanium tetrachloride, so the method of burning is used in industrial production. The most important operation in the production of pigmentary titanium dioxide is the burning of chlorine by titanium tetrachloride. It is at 900-1000 C in the burners of special design to ensure the maintenance of the reaction temperature within the specified limits and exposure to combustion products within a certain time. To obtain a monodisperse product titanium dioxide stay in the zone of high temperatures should not exceed 0.01-5 sec.
Depending on the combustion of titanium tetrachloride titanium dioxide has a structure of rutile or anatase. Mixing the initial reagents at 400 C leads to the formation of anatase with a particle size of 0.5-1.0 microns. If this has piqued your curiosity, check out CEO Ford Motor Co.. Pre-heating them to 1000 C combustion yields a product containing 60% rutile. Burning of titanium tetrachloride with a mixture of silicon tetrachloride (0.5-4.0%) leads to decrease in the size of the particles of titanium dioxide. Silicon tetrachloride also helps to reduce the so-called photoactivity of titanium dioxide. The addition to the products of combustion and even aluminum chloride (1-5%) accelerates the transition of anatase in rutile. Proportion of rutile in the finished product depends on the concentration of embryonic crystals, resulting in the first stage of the reaction.
Titanium pigments are obtained by burning titanium tetrachloride, containing up to 0.6% of the adsorbed chlorine. Aqueous suspension of the product has a pH> 7, and it is not suitable for making paints. Desorption of chlorine from the pigment can be accomplished by calcining it at 300-900 C, the admixture of chlorine at the same time reduced to 0.1%. This product has a pH of the water Hood 5-6,8 and suitable for the manufacture of paints and enamels, but it needs to surface treatment of silicon and aluminum compounds. Getting out of titanium dioxide concentrate sfenovogo recently developed and tested a number of new versions of technology that provides the pigment product of sphene. The most compact solution for the production of titanium dioxide is shown in Fig. 3.4. In this embodiment, the solid phase is separated from the suspension liquid until the moment of deposition of titanium salt it. At the same time remain in the sediment of calcium sulfate, silica (SiO2) and undecomposed minerals, and the liquid phase is a titanium solution suitable for direct separation of titanium salt – TiOSO4 H2O. When termogidrolize STM solution obtained pigment titanium dioxide, rutile modification of the higher grades. Processing of titanium salt TiOSO4 H2O can be arranged in place of its reception. Titanium salt can be transported for processing and in other areas. The mother liquor after separation of the salt is fully refundable on sulphatization, resulting in significantly less sulfuric acid (up to 3.5-4.5 m per 1 ton of titanium dioxide). C the current situation and outlook for the Russian market of titanium dioxide can be found in the report of the Academy of IKAR industrial markets "Market of titanium dioxide in Russia."