Recovery of Metals from Process Streams of Deep-Sea Ferromanganese Nodules by Adsorptive Bubble Techniques

Abstract

A method for the separation of Cu, Co, Ni, and Zn with varying degrees of selectivity from chemically treated deep-sea ferromanganese nodules is described. Quantitative removal of these species is achieved primarily by precipitate flotation of insoluble sulfides. Recovery of residual metal values of Cu, Co, Ni, and Zn in process rejects of the nodules is also possible. The quantitative removal of Pb and V, which are the most abundant toxic elements in nodules and tailings, is achieved simultaneously. Cationic and anionic surfactants are employed for collection depending on zeta potentials of the flocs generated upon addition of Na₂S to sample solutions. Separations are more selective and efficient at lower pH than previously reported for flotation of metals from nodules as insoluble hydroxides. Modifications resulting in slight improvements over previously employed high temperature sulfation processes are also described.