Nickel and Cobalt Recovery Through Carbonation and Sulfidation

Successful transitions to clean energy technologies require critical elements such as nickel (Ni) and cobalt (Co). However, the soaring demand for high-grade ores of high-grade ores of these elements have made them increasingly scarce, driving the search for alternative sources. Low-grade ores, such as mafic and ultramafic rocks, can potentially supply Ni and Co, but their concentrations are much lower than those of magnesium (Mg) and silicon. To elucidate the fundamental mechanisms of their concentration and recovery, we studied the carbonation and sulfidation of these elements in the presence of Mg, which also affected the sizes and morphologies of Ni/Co carbonates. We found that the co-existence of Ni/Co with Mg ions influenced the kinetics of Ni/Co carbonate formation, and that the difference between the carbonation and sulfidation kinetics of Ni/Co and those of Mg allows us to separate Ni/Co from Mg in mixed solutions. Our findings provide new insights for designing better processes for concentrating, separating, and recovering critical elements.