Zirconium Production
Zirconium Production
Zirconium ores are concentrated by gravitational methods with magnet and electric separation refining. The metal is obtained from its compounds, the concentrate is first decomposed. For this purpose two methods are used:
1. Chlorine treatment with coal at 900-1000°C. The main product, ZrCl4, is then sublimated and captured.
2. Fusing with caustic soda at 500-600°C or with soda (sodium carbonate) at 1100°C:
ZrSiO4 + 2Na2CO3 = Na2ZrO3 + Na2SiO3 + 2CO2;
3. Sintering with lime or calcium carbonate (adding CaCl2) at 1100-1200°C:
ZrSiO4 + 3CaO = CaZrO3 + Ca2SiO4;
4. Fusing with potassium fluosilicate at 900°C:
ZrSiO4 + K2SiF6 = K2ZrF6 + 2SiO2.
For cases (2, 3) all silica compounds are leached by water, the residue is decomposed by hydrochloric or sulphuric acid. The sintered fluorozirconate (4) is treated by acidified water, during which potassium fluorozirconate is dissolved; after cooling 75-90% is settled out.
Methods of Zirconium compounds separation from acidified solutions are as follows:
1. Zirconium oxychloride ZrOCl2x8H2O crystallization during hydrochloric solutions evaporation;
2. Hydrolytic sedimentation of the basic Zirconium sulphates XZrO2xYSO3xZH2O from hydrochloric or sulphuric solutions;
3. Zirconium sulphate crystallization Zr(SO4)2 adding concentrated sulphuric acid or by sulphuric solutions evaporation. After sulphates or chlorides roasting ZrO2 appears.
Zr sponge or powder is produced by ZrCl4, K2ZrF6 or ZrO2 metallothermic reduction. Chloride is reduced by magnesium or sodium, potassium fluorozirconate is reduced by sodium and Zirconium dioxide - by calcium or its hydride. Electrolytic pulverous Zirconium is obtained by smelting the mixture of zirconium halogenides and alkali metals chlorides. Compact ductile Zirconium is manufactured from pressed sponge smelting in vacuum arc furnaces as a consumable electrode. The ingots or iodide refining bars electron-beam melting is a method of high-purity Zirconium production.