Technical note Selective zirconium stripping of a loaded Cyanex 272 using Taguchi orthogonal array design M. Taghizadeh a , R. Ghasemzadeh a, * , S.N. Ashrafizadeh b , K. Saberyan c , M. Ghannadi Maragheh c a Department of Materials and Metallurgical Engineering, Iran University of Science and Technology, Tehran 16846, Iran b Department of Chemical Engineering, Iran University of Science and Technology, Iran c Jabr Ibn Hayan Research Laboratories, P.O. Box 11365-8486, Tehran, Iran Received 21 May 2007; accepted 11 July 2007 Available online 7 September 2007 Abstract In this study the effects of various stripping parameters such as complexing agent (EDTA), organic to aqueous ratio (0.5, 1.0, 2.0), acid type (hydrochloric, sulfuric, sulfuric + hydrogen peroxide) and their concentrations (0.5, 1.0, 2.0 N) were investigated on zirconium stripping efficiency from loaded Cyanex 272 in kerosene. Results showed that, all of these parameters had significant effect on the selec- tive zirconium stripping. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Zirconium; Hafnium; Taguchi; Stripping; Cyanex 272 1. Introduction Zirconium ores contain small amounts of hafnium that must be removed when producing nuclear grade zirconium. In our primary experiment’s it is found that Cyanex 272 as an alternative for TBP/nitrate system can selectively extract zirconium from 2.0 M nitric acid. In addition to the sepa- ration factor achieved in the extraction process, some remaining impurities can also be removed by scrubbing or selective stripping from loaded organic phase. Despite the large number of studies related to the solvent extraction separation of zirconium and hafnium, Levitt and Freund (1956), Sato (1970), El-yamani and Farrah (1978), Shults and Larsen (1950), Kalyanaraman and Khopkar (1978) and Da Silva et al. (2000), selective stripping of zirconium has never been reported. Ramachandra Reddy and Rajesh Kumar (2004) showed that sulfuric acid is the proper reagent for zirconium stripping from loaded Cyanex 272, although the addition of some hydrogen peroxide to sulfu- ric acid can improve stripping efficiency. However, haf- nium stripping has not been studied in any literature review yet. Therefore some factors affecting selective strip- ping of zirconium, such as acid type and their concentra- tions, organic to aqueous ratio (O/A), hydrogen peroxide and complexing agent have been investigated in this study. 2. Experimental 2.1. Experimental design In the present study, four factors in three-levels, i.e., complexing agent, organic to queues ratio, acid type and also acid concentration were considered. The stripping parameters and their selected levels are presented in Table 1. The experimental design for selective zirconium stripping parameters using L9 orthogonal array and experimental results together with the calculated separation factors are shown in Table 1. The results reported in this article are the mean values of two replications at each set of experiment. 0892-6875/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.mineng.2007.07.002 * Corresponding author. E-mail address: rgzadeh@iust.ac.ir (R. Ghasemzadeh). This article is also available online at: www.elsevier.com/locate/mineng Available online at www.sciencedirect.com Minerals Engineering 20 (2007) 1401–1403