Electroleaching of polymetallic ocean nodules to recover copper, nickel and cobalt

The key for successful and efficient dissolution of copper, nickel and coba lt from ocean nodules depends on prior reduction of the manganese and ferri c oxides with which the above valuable nonferrous metals are interlocked. W e have shown that through the application of negative reduction potential o r DC current, significant reduction of manganic and iron oxides in the ocea n nodules can be achieved, thus liberating the occluded copper, nickel and cobalt for easy dissolution in an acid medium. Polarization studies using a slurry electrode system indicated that maximum dissolution of iron and man ganese due to electrochemical reduction occurred at negative DC potentials of -600mV(SCE) and -1400mV(SCE). Electroleaching of the ocean nodules at th e above negative applied DC potentials resulted in significant dissolution of copper, nickel and cobalt in IM H2SO4. (C) 2001 Published by Elsevier Sc ience Ltd. All rights reserved.