A new technique for extracting zirconium form Egyptian zircon concentrate |
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| Institution: | 1. Geology Department, Faculty of Science, Suez Canal University, Ismailia, Egypt;2. Geology Department, Faculty of Science, Port Said University, Port Said, Egypt;3. Geological Follow Up Development, Exploration Division, Nuclear Material Authority, Egypt;1. Key Laboratory of Automobile Materials of MOE and School of Materials Science and Engineering, Jilin University, Changchun 130012, China;2. College of Science and Laboratory of Materials Design and Quantum Simulation, Changchun University, Changchun 130022, China;1. Advanced Biofuels Lab, Institute of Mechanical, Process and Energy Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, UK;2. Department of Engineering Sciences Angström Laboratory, Uppsala University, Uppsala, Sweden;3. Nanotechnology and Functional Materials Division, Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, Uppsala, Sweden;1. School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi’an, 710072, PR China;2. Univ Lyon, INSA-Lyon, CNRS, MATEIS UMR5510, F-69621, Villeurbanne, France |
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| Abstract: | Zircon is the most important commercial source of zirconium, its compounds and alloys. Several methods are used for industrial processing of zircon for production of zirconium dioxide and tetrachloride. These methods include sintering of zircon with sodium carbonate or sodium hydroxide or calcium oxide or calcium carbonate and with potassium fluorosilicate, chlorination of zircon mixture with coal in blast furnace and carbidization of zircon in a mixture of coal in electric arc furnace. All these methods are carried out at high temperatures and have many disadvantages.The present work illustrates a study of a new technique for extracting zirconium from Egyptian zircon concentrate by its simultaneous ball-milling and pressure alkaline leaching, to improve the recovery of zirconium from zircon. Experiments were carried out in stainless steel ball-mills of cylindrical shape under different conditions of temperature, pressure and time. The ball-mills were heated and mechanically rotated in an electric furnace by means of roll mechanism.The filtrate after leaching of zircon, containing excess of sodium hydroxide was regenerated by its treatment with calcium hydroxide for purification from silicon impurity. Then, the solution was evaporated to the desired concentration (500 g/l Na2O) and recycled to the reactor of leaching.The results obtained show that complete recovery of zirconium from zircon (99.7%) by simultaneous ball-milling and alkaline leaching was attained at 250 °C within 3 h, using amount of sodium hydroxide 150% of theoretical requirement (satisfying favourable conditions of zirconate cake for subsequent acid leaching).The standard free energy (ΔFo) and equilibrium constant (K) of the reaction of zircon with sodium hydroxide were calculated as—19.58 k cal mol? 1 and 2.29 · 1014, respectively. The kinetics of the technological alkaline processing of zircon in ball-mall autoclaves was studied over the temperature range 150–275 °C. |
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