Transferring behavior and reaction kinetics of saprolitic laterite during metalized reduction in the presence of calcium fluoride

Abstract

Laterite ore is the most important primary base source of nickel, however low-nickel saprolitic laterite is difficult to economically utilize. This study aims to investigate the proposed nonmolten-state metalized reduction (NSMR) technology for saprolitic laterite. First, the thermodynamics of NSMR in the presence of calcium fluoride was analyzed using laterite from Southwest China as raw material. Then, the process for concentrating nickel and iron under different factors was systematically studied. Subsequently, the behavior of nickel and iron during the NSMR process was analyzed. Lastly, the kinetics of the metalized reduction process was examined, and the reaction apparent activation energy was determined. Results showed that nickel and iron recoveries can reach as high as 92.9% and 84.6%, respectively, and these two metals are produced in the form of nickel–iron concentrate, which can be used as raw material for steel making. Calcium fluoride can inhibit nickel from entering the nickel-bearing magnesium silicate phase, avoiding the inertness of nickel and considerably increasing its metallization. The reaction process of NSMR conforms to the Avrami–Eroféev reaction model (n = 0.5) and the apparent activation energy (Ea) is 309.16 kJ mol−1. This research demonstrates the theoretical perfection of the proposed NSMR technology, which may realize the commercial utilization of worldwide low-nickel ore in a long-term stagnant state.