Kinetics analysis of atmospheric agitation leaching of limonitic nickel ore in sulfuric acid by incorporating the effect of particle size distribution in shrinking core model

The shrinking core model (SCM) has been widely used to model the kinetics of solid-liquid reactions such as metal extraction from ore minerals. Most studies considered a single-sized grain, and the particle size variation of the ore was disregarded. In the present study, the kinetics analysis of limonitic nickel ore in sulfuric acid by incorporating the effect of particle size distribution in SCM was made. The approach was used to evaluate the effects of leaching temperature (65 to 95°C) and agitation speed (250 to 400 rpm) on the leaching kinetics of nickel from limonite ore. The analysis showed that the rate-determining step was shifted from diffusion through unreacted core to an interface chemical reaction. the increase in the extracted nickel by the increase in agitation speed also indicated that the leaching rate is chemical reaction-controlled. This investigation results give an insight into incorporating particle size distribution's effect in the shrinking core model on the rate-determining step in the leaching of limonite ore in sulfuric acid at atmospheric pressure.