The leaching rate of a manganese nodule was discussed. The manganese nodule was crushed to 250 mesh under (-61μm) and leached with 1.0 N hydrochloric acid in the temperature range of 30 to 70°C. The results are summarized below.
The leaching rate can be represented by the volume reaction model, and the leaching rate of Ni and Cu are the second order with respect to each content remained in the sample. The dissolution of Fe ceases on the way of leaching, and for the soluble portion of Fe the leaching rate of Fe is also the second order. The leaching behavior of Co is analogous to that of Mn, i. e., both of them dissolve only slightly at lower temperature, but highly at 70°C. The leaching rates of Co and Mn at 70°C are also the second order.
The apparent activation energies for Cu, Ni and Fe leaching are 41.2, 81.1 and 43.3 kJ/mol, respectively, and the overall reaching rates appear to be controlled by the heterogeneous reaction.
