Optimization of laterites leaching by application of sequential design of experiments

The sequential designed experimentation was applied for leaching of Ni-Fe-Mg containing serpentine ores. The experiments were arranged in two sequences, according to the 2IV4-1 fractional factorial experimental design. Six factors were examined, i.e., the material sample, solid-to-liquid ratio (S/L), acid type and its concentration, leaching temperature, and stirring speed. The analysis of variance was used to establish the relation between tested factors, their interactions, and metals recovery. All the derived empirical models were of prime statistical importance. The obtained results showed that the recovery of Ni was dependent mainly on the material sample, the concentration of acid as well as their interaction, and temperature. The recovery of nickel at the optimal leaching conditions was high (93%). The dissolution of other metals was below 84% (Fe) and 54% (Mg).