Removal of silicon in acid leaching and flocculation processes during zirconium oxychloride octahydrate production

The efficiency of silicon removal technology by acid leaching and flocculation during zirconium oxychloride octahydrate (ZrOCl2 center dot 8 H2O) production has been improved. The optimum conditions of acid leaching were found to be as follows: transiton material, 300 g; HCl (6 mol/L), 600 mL; leaching time, 4 h; and leaching temperature, 100 degrees C. The nonionic polyoxyethylene lauryl ether (AEO9) was adopted as the flocculant. The optimum flocculation conditions were found to be as follows: temperature, 40 degrees C; flocculant amount, 10 ml (concentration 1%); time, 1 h. The zirconium oxychloride solution after purification contained 36 ppm SiO2 and 160 g/L ZrOCl2. The polymerization and flocculation mechanisms of silicic acid were analyzed. Results of Fourier-transform infrared, scanning electron microscopy, nuclear magnetic resonance, and Brunauer-Emmett-Teller analyses showed the main transformation and properties of the products in the acid leaching and flocculation processes. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.