Beach Sand Heavy Mineral
Beach Sand Heavy Mineral a placer deposit of heavy minerals eg zircon, ilmenite or rutile on a contemporary or ancient beach or along a coastline. Investigation of radioactive minerals like monazite by the erstwhile Geological Survey of Pakistan around the cox's bazar sea beach area started in 1961 and a number of precious heavy minerals were identified the same year. Geologists of the Pakistan Atomic Energy Commission carried out reconnaissance work in 1967 and found that the beach sand contains economically important heavy minerals.
After systematic surveys during 1967 to 1969 it was recognised that a potential zone of heavy minerals exists along the entire coastal belt, mainly from Cox's Bazar to Badarmokam, and in some areas of maheshkhali, kutubdia and Matarbari islands. Later, in 1975, a pilot plant was installed at Kalatali, Cox's Bazar with the cooperation of the Australian Government to sample, separate and assess the commercial viability of the heavy mineral content in the placer deposits. In this plant, a flow sheet adopted by the Australian Mineral Development Laboratory was used to separate heavy minerals. By 1985 the nearly 550 km-long coastline of Bangladesh was surveyed either partially or completely to map the beach sand heavy minerals. It was found that the reserves were concentrated mainly along the sea beaches of chittagong and Cox's Bazar districts. On the basis of surveys carried out so far along the coast of Bangladesh a number of heavy mineral placers are delineated. Until now seventeen placer deposits are found; fifteen are in the Cox's Bazar-Chittagong sea beaches and nearby offshore islands. In fact seven are from the Cox's Bazar-Teknaf sea beaches (Cox's Bazar, Inani, Silkhali, Teknaf, Sabrang and Badarmokam), seven from Maheshkhali Island, one each from Matarbari, Kutubdia and Nijhum islands, and Kuakata.
All the seventeen deposits include 20.5 million tons of raw sand, which contains 4.4 million tons of heavy minerals (sp gr > 2.9). Only eight types of economically important heavy minerals, namely, ilmenite, magnetite, zircon, rutile, garnet, leucoxene, kyanite and monazite occur in these deposits. The total stock of these eight types of heavy minerals in these seventeen deposits is 1,761,000 tons. In Bangladesh, industrial uses of beach sand heavy minerals are as follows:
About 60% of all Zircon is used in foundry facing works, while 15% is consumed in the manufacture of zirconium metal, alloys and chemicals. Zircon is extensively used in refractory products and in the manufacture of glass. rutile is used as raw material in the pigment industry. The industry consumes about 66% of the total rutile production, while 18% is used in welding rod coatings. Ilmenitea source of TiO2 which is used chiefly as white pigment. Ilmenite is extensively used in welding rod coatings. About 90% of the total Garnet production is used in the manufacture of emery cloth, paper, wheel and grinding stones. Magnetite used chiefly as a source of pig iron, which is the primary material for the production of cast iron, wrought iron, malleable iron and the many varieties of ordinary and special steels. Monazite is a source of rare-earth metals and thorium. Leucoxene is being used as a substitute for rutile with the increasing demand of TiO2 material. Kyanite serves as a source of aluminium . It is extensively used in the manufacture of refractory and foundry products. [Sifatul Quader Chowdhury]