Pressure Leaching of Limonitic Laterite Ores in H2SO4-Mg(NO3)2 Medium

A limonitic laterite ore from Indonesea was treated by pressure leaching in H2SO4-Mg(NO3)(2) medium, using Mg(NO3)(2) as an oxidant. Experiments were conducted in order to determine the optimum conditions by studying various parameters, including Mg(NO3)(2)/ore mass ratio, initial acidity, reaction temperature, holding time and liquid/solid ratio. Pressure leaching experiments showed that nickel, cobalt and iron extractions were 90.8 %, 91.9 % and 2.1 % after 60 min of leaching at 493 K with 0.06 g/g Mg(NO3)(2)/ore mass ratio, 140 g/L initial acidity and 2 mL/g liquid/solid ratio.The total decrement of acid consumption was 72 g H2SO4/kg ore in the presence of Mg(NO3)(2).