Preconcentration strategies in the proce

A number of physical separation techniques for nickel (Ni) laterites have been investigated at laboratory and pilot plant scale and reported in the open literature. These included sink–float (or dense media) separation, gravity separation, magnetic separation, electrostatic separation, roasting and flotation. The information located so far and reported in the literature review by Quast et al. suggests that all these techniques, although providing some degree of upgrading, have not been incorporated into full plant operations as yet. The only successful preconcentration technique incorporated into some commercial operations has been the removal of a coarse product containing lower Ni values than the feed. In this work, the application of a number of physical separation techniques (screening, gravity, magnetic separation and without roasting) has been investigated in the laboratory for upgrading the high magnesite laterite, causing a noticeable increase in Ni and Co recovery into the concentrate product with temperature up to a certain point, but this effect was reversed at 650 °C. Overall, the application of the selected techniques failed to produce any significant Ni grade enhancements for these laterite ores, confirming that the complex mineralogy compromises any significant upgrading in Ni values by standard physical separation techniques.