Coastal ecosystem and environmental aspects of placer mining

Abstract

The world demand for mineral raw material is expected to increase more than threefold with the increase in population and the industrilization. Though, India's mineral resources generally appear to be sufficient to meet the projected demand through the beginning of century, resources of some metals may be insufficient on land. Therefore further discoveries and investments are needed elsewhere to meet the rising demands. In a quest to search for new areas, man has viewed the ocean as a last frontier for raw materials. The waters of the oceans and the seabed that underlies contain vast quantities of minerals and metals. Though seawater is known to contain all the known elements in dissolved form, all the elements are not suitable for exploitation in commercial quantities. However, sand, gravel, shells and phosphorites, tin and other metals have been profitably recovered from the seabed for many centuries. Seabed is known to contain four kinds of marine minerals, viz., terrigenous, biogenous, chemogenous and hydrothermal. Among them, coastal and offshore placers are typically terrigenous in nature. Placers such as ilmenite, magnetite, monazite, zircon and rutile are the major minerals in this group, and they are reported from many beaches along the coasts of Maharashtra, Kerala, Tamil Nadu, Andhra Pradesh, and Orissa.