Terrestrial ferro-manganese nodules formed in limestone areas of the Ryukyu islands II. Partitioning of major and minor chemical constituents determined by selective chemical leaching technique.

Abstract

Selective chemical leaching technique has been applied to the study on the partitioning of major and minor constituents into individual mineral species in ferro-manganese nodules formed in limestone areas of the Ryukyu Islands.The technique includes the use of 25% CH3COOH, 1 M NH2OH-HCl-25 % CH3COOH and 30% H202 solutions.Treatment with 25% CH3COOH solution led to the leaching of 51% of Ca, 0.6% of Fe and 1.5% of Mn. Successive leaching with 1 M NH2OH-HCl-25% CH3000H solu tion led to the leaching of 32% of Fe and almost 100% of Mn. The rate of leaching is largely dependent on the mineral components in the nodules.Minor elements are concentrated in the ferro-manganese fraction which is leached with 1 M NH2OH•HCl-25% CH3COOH solution. The rate of leaching is 100% for Co, 93% for Cu, 87% for Pb, 82% for Cd, 76% for Ni and 45% for Zn. Some parts of the elements remained insoluble in the above solutions.The remained fraction may have been associated with either stable clay lattice structure or stable oxide forms of lithogenous origins.