TITLE:
Effect of Tsunami in the Ilmenite Population: An Examination through X-Ray Diffraction, Scanning Electron Microscopy and Inductively Coupled Plasma Atomic Emission
AUTHORS:
Babu Nallusamy, Sinirani Babu, M. Sundararajan, P. Seralathan, R. Bhima Rao, P.N. Mohan Das
KEYWORDS:
Tsunami, Ilmenite Population
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.9 No.11,
November
20,
2010
ABSTRACT: Kerala state in the SW part of Indian subcontinent hosts one of the best beach placer deposits in
the world. The near shore deposit is ~140Mt and is very rich in heavy minerals, often up to 70%,
and ilmenite forms its chief constituent. The seasonal enrichment of this deposit takes place
through monsoonal activity and the recent tsunami (24 December 2004) had significantly
contributed its share. Mineralogical and chemical variation of the surface (pre- and posttsunamigenic) as well as subsurface ilmenites (4-5m depth) of this deposit has been investigated. SEM examination on ilmenites of pre-tsunamigenic period conveys that the micromorphology represents mostly of mechanical activities rather than chemical and solution activities. Both post-tsunamigenic and subsurface ilmenites were influenced dominantly by solution and chemical alteration. The pre-tsunamigenic (surficial) ilmenite grains consist only of rutile as an
altered product with a small FeO – Fe2O3 ratio. However, the presence of considerable altered products such as rutile and pseudorutile in the post-tsunamigenic and subsurface ilmenite indicates that the ilmenite alteration is in an advanced state. Regarding trace element composition, it was found that Al, Mg, Na, Ca, Cd, Co, K, Sr and Pb have higher contents in both core and post-tsunamigenic ilmenite than the pre-tsunamigenic ilmenite. These elements
play an important role in understanding the behavior of the minerals during beneficiation and
further processing. The relative lesser content of such elements in the onshore pre-tsunamigenic
ilmenite grains reveals that the chemical leaching has not been active compared to the ilmenite
concentrates from the shallow sea that have been brought by the tsunami and also to that have
been deposited earlier and now seen underneath up to a depth of ~5m.