| Sulphuric acid pressure leaching of limonitic laterites is the process of choice to recover nickel and cobalt from equatorial lateritic ores, replacing the energy intensive pyrometallurgical methods. This process gives a high nickel and cobalt extraction (more than 90%) and also a high selectivity due to simultaneous iron and aluminum dissolution and precipitation. This thesis presents the results of experiments carried out using batch pressure leaching techniques with sulphuric acid. A titanium autoclave equipped with acid injection and sample withdrawal units was employed. The effect of temperature (230-270{dollar}spcirc{dollar}C), acid concentration (0.1-0.4 M), pulp density (10-30%) and degree of agitation (400-600 rpm) on nickel extraction were studied. The evolution of the nature of solid products during leaching was also studied. The rate controlling step was found to be intraparticle (pore) diffusion and the Jander equation was proposed to fit the experimental data. |
