1-12 reduction leaching of cobalt crust was carried out to study the optimum mixing conditions ofNH3-(NH")2C03-CuSO4, solutions. Cobalt and Ni was extracted 90% or higher in the 2M NH3-0.5M(NH4)2C030.1MCuSO4 solution using a Pt catalyst loaded on polytetra-fluoroethylene (PTFE) under 60°C, 0.5atm of H2 pressure, 3.3g/1 of slurry concentration for 2-3h.


The deep-sea oxide minerals such as manganese nodules and cobalt crusts are expected as unlimited resources of Co, Ni and Cu in the 21st C, although their contents are low. Though many researches have been carried out including several pilot tests (Okabe and Okuwaki, 1979 a, b) it is believed that a long lead time would be required for operating the commercial plant. Although CO (Agarwal et al.,1978) and SO2 (Rokukawa,1992) reduction processes in NH 3-(NH4)2C03 solution have been developed, one of the most promised processes under such environment is H 2 reduction leaching in NI-I 3-(NH4)2C03 solutions which has not been studied yet. In such process clean H 2 is used as a reducing agent, and CO2 emitted in the process can be fixed simultaneously as MnC03. The problems in I-I2reduction leaching are poor solubility and activity of 1-1 2at low temperature. On the other hand when H2 reducton is carried out at high temperature and pressure, each ion of Co, Ni, Cu in the leaching solution might be reduced to the metals. A hydrophobic Pt catalyst loaded on polytetrafluoroethylene WTFE) membrane filters to activate I-I 2 gas and a redox couple of Cu(II)-Cu(I) ions arc enable to proceed the H2 reduction leaching under moderate temperature and atmospheric pressure. In the present paper, we report the oputimum conditions for a H2 reduction leaching of cobalt crust using a Pt/PTFE catalyst in NH 3-(NH4)2CO3-CuSO4 solutions.

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