Leaching kinetics and reactivity evaluation of ferronickel slag in alkaline conditions

This paper evaluates the reactivity of individual mineral phases of ferronickel slag (FNS) based on the back-scattered electron images analysis (BSE-IA) and presents the leaching kinetics of FNS in NaOH solutions, aiming to reveal the interrelationships among physicochemical properties, leaching behavior and reactivity of FNS. There are three typical phases identified in water-quenched FNS, namely FNS I, II and III phase. The FNS I phase is more prone to dissolve and preferentially participate in the reaction process than the other two phases. The dissolved Mg from FNS is mainly involved in the formation of hydrotalcite and N-M-S-H gels. Cr could not be detected during the leaching process. The activation energy for the leaching of Si and Al is 80.47 and 49.45 kJ/mol, respectively. A method for rapid evaluation of the reaction activity of FNS given the evaluation index of the individual leaching ratio of Si and Al is proposed.