Zircon plasma processes

Plasma oxidation was suggested lately as a very promising way to treat VOCs in air (Oda et al., 1996, 2003). Efforts were made to study the effect of porous and various dielectric materials such as zirconates and titanates (Roland et al., 2002). It is no wonder, therefore, that the combination of titanium dioxide and plasma processes was tested as well. 

Ramachandran CS, Balasubramanian V, Ananthapadmanabhan PV. Synthesis, spher-oidization and spray deposition of lanthanum zirconate using thermal plasma process. Surface Coatings Technology. 2012 206 3017-3035. 

Decomposition of Zircon. Zircon sand is inert and refractory. Therefore the first extractive step is to convert the zirconium and hafnium portions into active forms amenable to the subsequent processing scheme. For the production of hafnium, this is done in the United States by carbochlorination as shown in Figure 1. In the Ukraine, fluorosiUcate fusion is used. Caustic fusion is the usual starting procedure for the production of aqueous zirconium chemicals, which usually does not involve hafnium separation. Other methods of decomposing zircon such as plasma dissociation or lime fusions are used for production of some grades of zirconium oxide. 

The high temperatures attainable in a plasma furnace, with no restrictions with regard to factors such as the furnace atmosphere or the crucible material, has made processing by thermal decomposition a practicable and useful method. A good example is the thermal decomposition of low-cost zircon (ZrSi04) to produce zirconium dioxide (Zr02). The fur-... 

Production Zirconia is usually produced from zircon, ZrSi04. Zircon sands are first melted with sodium hydroxide and transferred to zirconium (IV) oxide. With addition of coal, the zirconium oxide is transferred to zirconium carbonitride in a plasma arc, which is converted again to zirconium (IV) chloride with chlorine. The chloride is reduced to zirconium with magnesium in a helium atmosphere at 800°C in the so-caUed Kroll-process ZrCLt -I- 2Mg —> Zr -1- 2 MgC. ... 

The oxide of pure zirconium (Zirconia = Zr02) is obtained from sands of zircon (ZrSi04) or baddeleyite (Zr02) by a chemical processes via of chlorination and thermal decomposition, alkali oxide decomposition or lime fusion or by plasma decomposition [30],... 

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