Leaching of rare earth elements from phosphate rock using sulfuric acid: Process optimization and kinetic studies

Document Type : Original Article

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Nuclear Materials Authority

Abstract

Rare earth elements (REEs) are crucial raw materials for ‘smart’ electronic devices and emerging renewable energy resources.  Accordingly, the global attention for the secondary REEs resources such as phosphate rock is increased.  Recognizing effective leaching of REEs from phosphate rock is essential from a strategic perspective for addressing the world demand highly growth rate.  The present study investigates the leaching of REEs from phosphate rock using sulfuric acid.  The impact of the main variables on the leaching performance was examined.  Design of experiments (DoE) methodology was applied for optimization the REEs leaching process.  The anticipated data declare that about 96.6% leaching percent could be achieved according to the following conditions: 1.5 M sulfuric acid concentration, 30 mL/ g as liquid/ solid ratio, 55 oC reaction temperature and stirring time of 1.0 hr. shrinking core model (SCM) was applied to explore the kinetic attitude of REEs leaching process.  The exhibited results deduced that leaching process is well depicted using the ash layer diffusion kinetic model.  In addition, the activation of energy of REEs leaching process was found to be equal 9.01 kJ/mol.

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