National Institute for Resources and Environment (NIRE) has developed a hydrometallurgical process for recovery of Co. Ni. and Cu from cobalt rich crusts. NIRE process are the use of a mixture of aqueous ammonium carbonate and ammonium sulfite solution as leaching reagents extraction of Ni and Cu in the pregnant liquor with LIX84 as organic solvent and alcohol deposition of Co in the residue liquor. The flowsheet for recovery of Co. Ni. and Cu from cobalt rich crusts are presented.
Cobalt rich crusts exist in stratiform states several to more-than-ten mm thick over the surfaces of rockbed from the tops to the slopes of seamounts 800 to 2.400 m deep in the whole world. Attention is drawn to them as the third most important deep seabed mineral resources. next to manganese nodules and hydrothermal polymetallic sulfides. Cobalt rich crusts contain Mn. Fe. Co. Ni. Cu etc. and their contents of Co are higher than those of manganese nodules. so the cobalt rich crusts are looked upon as promising cobalt resources. For the purpose of recovery of Co. Ni. and Cu from the cobalt rich crusts. this paper describes the leaching of them by using mixture of aqueous ammonium carbonate and ammonium sulfite solution (Rokukawa.1992), and the separation of Co. Ni. and Cu from the leach liquor by solvent extraction (Rokukawa. 1993). therefore the precipitation of Co from residue liquor by alcohol (Rokukawa.1994).
The cobalt rich crusts used for a series of experiments were collected from a seamount located in the equator zone of the Central Pacific Ocean and stored in air. In comparison with the manganese nodules collected from the seabed of the Central Pacific Basin (Rokukawa1990) the crust samples contain more Co and Fe. less Cu.