Abstract
The extraction of nickel, cobalt and copper from cobalt crusts was carried out by using ammoniacal alkaline solution. The cobalt crusts which were collected from the seamountain of the Pacific Ocean were used grinding below 74μm. The leaching test was done by using ammonium hydroxide, ammonium chloride, ammonium sulfate, ammonium sulfite and ammonium carbonate as leaching reagent.
In the leaching using only ammonium salt solution except for ammonium sulfite, the extraction of metallic components was low. On the other hand, the addition of ammonium sulfite as the reducing agent to ammonium salt solution increased the extraction of cobalt, nickel and copper considerably. For instance, the extraction rates of the metallic components on leaching of ADO1 at 80°C for 60 minutes in the mixed solution of 100 g/l (NH4) 2CO3 and 50 g/l (NH4) 2SO3 were 97.7% for Co, 95.9% for Ni, 94.1% for Cu, 0.55% for Mn and 0.19% for Fe, respectively, and the leaching residue was identified as manganese carbonate, MnCO3.
Concequently, cobalt, nickel and copper were selectively extracted from the cobalt crusts with the mixed solution of ammonium carbonate and ammonium sulfite.
