Electron Microscopic Studies of Ilmenite from the Chhatrapur Coast, Odisha, India, and Their Implications in Processing

Ilmenite from the Chhatrapur coast, Odisha, India, was studied using optical microscope, X-ray diffraction, particle size analysis, and electron microprobe to decipher their micromorphology, texture(s), and elemental composition. The micromorphological features by electron microscope indicate that weathering processes such as mechanical and chemical, affected the placer heavy mineral ilmenite. These detrital ilmenites contain TiO2 in the range of 50.25% to 55.41% and FeO 42.72% to 49.99% in addition to Al2O3, MgO, MnO, CaO, Na2O, Cr2O3, NiO, ZnO, ZrO2, V2O5, and HfO2 (0 to 0.034%). Ti/(Ti + Fe) ratio in the ilmenite varied from 0.413 to 0.5, which indicates the effect of weathering/oxidation confirming microscopic observations. All the results revealed that these ilmenite grains were derived from the gneissic/granitic, basic and high grade metamorphic rocks, belonging to the Eastern Ghats Group of the Precambrian complex of coastal Orissa. 1. Introduction Ilmenite (FeTiO3), an important and the most abundant ore mineral of titanium, occurs in India along the coastal beach sands of Odisha, Andhra Pradesh, Tamil Nadu, and Kerala states. One important occurrence in Odisha is in the coastal stretch over a strike length of 18？kms (covering a total area of 26？Km2) between Gopalpur in the south and confluence of the Rushikulya river with Bay of Bengal at Ganjam in the north [1–6]. The Indian Rare Earths Limited (IREL), a public sector undertaking of the Department of Atomic Energy, Government of India, is mining and processing ilmenite along with other heavy minerals like garnet, monazite, rutile, sillimanite, and zircon from these sands since 1984, at its Chhatrapur (Matikhalo) plant. Several researchers have studied the ilmenites from across the world to assess the provenance from the geochemistry of ilmenites [7–11]. However, no in depth study has been undertaken on the variation in the chemical composition from grain to grain for the Chhatrapur beach placer ilmenites, aside from some preliminary investigations [12, 13] and the work on surface microtextures [14]. In view of this, the authors present here a detailed mineral geochemistry (by EPMA) for characterizing the ilmenites from the beach sands of Chhatrapur area, Ganjam district, Odisha. The results have been interpreted based on the present study for not only the understanding of the provenance of the ilmenites in this region but also their effects in processing and/or utilization. 2. Geology of the Area The coastal area of Odisha (from Gopalpur to the Mahanadi delta) runs in a NE–SW direction, nearly