Comparison of leaching and heavy liquid separation methods for low grade nickel lateritic ore

Abstract

In this research, some tests such as atmospheric agitation leaching and gravity methods were performed using a low Ni grade lateritic sample taken from southern Iran. In these samples, Ni grade was 0.38% and the main minerals were serpentine, hematite and quartz. In this work, the response surface methodology was used to fit models to the experimental results. Hence, variables (temperature, sulphuric acid dosage and pulp density) were designed in central composite design method using DX7 software. Then, models for four results (Ni grade in leaching solution, and Ni, Mg and Fe extraction) were achieved, which could suggest that Ni and Mg extraction patterns are near to each other, while the Fe extraction pattern is different. Then, more physical tests (heavy liquid separation) were carried out to confirm the last results. In addition, the leaching experimental results were optimised and obtained under medium conditions at 4 h, 80°C, 2.59 N sulphuric acid and 200 g L^− 1 pulp density; it is possible to extract >75% of Ni. However, under intensive conditions (especially ∼95°C), Ni extraction grows up.