Fe(III) removal from a synthetic chloride leach solution of nickel laterite by N,N–diethyldodecanamide

Abstract

In recent years, leaching with chloride solutions has attracted much interest for nickel laterite processing due to its high leaching rate, fast kinetics and the recycling of lixiviant and HCl. However, the presence of large amounts of Fe(III) in the pregnant leach solution becomes a big challenge for the recovery of nickel and cobalt.A solvent extraction (SX) method using N,N-diethyldodecanamide (DEDA) to remove Fe(III) from a synthetic chloride leach solution of nickel laterites was investigated. It was found that using an organic system consisting of 30% (v/v) DEDOA and 30% (v/v) isodecanol (as phase modifier), over 90% Fe(III) was extracted from the strong chloride solution (6M Cl) in a single contact and high selectivity of Fe(III) over other metals was obtained in the pH range tested. The Fe(III) extraction increased substantially with the increase in chloride concentration. High Fe(III) stripping efficiency was obtained using water. The Fe(III) extraction McCabe–Thiele diagram shows that almost all Fe(III) can be extracted using three stages at an A/O ratio of 1.25:1. The Fe(III) stripping McCabe–Thiele diagram shows that almost all Fe(III) can be stripped using two stages at an O/A ratio of 2:1. Extraction and stripping kinetics were very fast and phase separation was good and fast for practical operation.