11:45 〜 12:00
[HCG24-11] Exploration for radioactive and REE containing minerals in placer sands of Bangladesh
キーワード：Radioactive materials, Rare Earth Elements, Monazite, Zircon, Uranium, Thorium
Placer minerals in the form of recent sand deposition are distributed in all over Bangladesh both in beach and fluvial environments. Studies have been conducted to identify the sand composition in both geological environments, resulting the presence of several major minerals such as ilmenite, magnetite, rutile, zircon, garnet, monazite, kayanite, leucoxene as heavy minerals and silica as light minerals. All these minerals have variety of industrial uses. Among them, zircon and monazite are reported to contain radioactive materials like uranium-thorium and rare earth elements (REEs). As nuclear geoscientific research activity of Bangladesh Atomic Energy Commission (BAEC), the present study reports the status of exploration of these radioactive and REE containing minerals in Bangladesh territory.
After the independence of Bangladesh, placer deposits are explored by different government organizations in last 50 years. BAEC is the pioneer among them, working at the coastal areas and identified seventeen placer deposits with specific reserve estimation at individual heavy mineral deposit. Through R&D of various geological institutions, similar types of heavy minerals were identified in several river bars. A mineral processing plant has been set up at Beach Sand Minerals Exploitation Centre (BSMEC), Cox’s Bazar to identify the feasibility of commercial exploitation of those minerals. However, low physical grade, present market price and limited study on detail reserve of those minerals did not allow either government or private companies to undertake any commercial venture. Any feasible value addition to the quality and quantity is, therefore, necessary for viable commercial utilization of the identified minerals. Quantification of Beach placer deposits of Bangladesh are found to be radioactivity containing materials in several heavy minerals with specific presence of uranium and thorium.
Being the authority of managing radioactive materials in Bangladesh, BAEC has been continuing to quantify the uranium and thorium content in different placer minerals. The radioactivity measurements indicated contributions from Naturally Occurring Radioactive Materials (NORMs), such as thorium and uranium radioactive series and of 40K. The activity concentrations were found to be equivalent to maximum 37,600 ppm of thorium and 5,120 ppm of uranium. In separate other studies, the presence of 526-2557 ppm thorium and 140-1212 ppm uranium is reported in several fractions of processed zircon. Besides radioactive elements, monazite of Bangladesh is also characterized by the presence of various REEs, e.g. cerium, yttrium, lanthanum and neodymium. With an estimated reserve of over 160,000 tons of zircon and 17,000 tons of monazite in placers deposits at Bangladesh coast, the quantity of uranium and thorium could be significant. Similar REEs were identified in fluvial environments of Brahmaputra, Teesta and Jamuna. Results from multiple researches showed the presence of several rivers contain as high as 10% of heavy minerals, in which 0.35-0.96 wt% monazite is composed of total REEs of 121-184 ppm. Therefore, exploration for radioactive materials and REEs in placer sands would be a massive development in natural resource research in Bangladesh.
References: BSMEC, 1994; Ramesh et al., 2000; Zaman et al., 2012; Sasaki et al., 2015; Zaman et al., 2016; Rajib et al., 2016; Khalil et al., 2017; Deeba et al., 2019; Rajib et al., 2019; Hossain, 2019; Rajib and Oguchi, 2020; Aminur et al., 2021, 2020.
After the independence of Bangladesh, placer deposits are explored by different government organizations in last 50 years. BAEC is the pioneer among them, working at the coastal areas and identified seventeen placer deposits with specific reserve estimation at individual heavy mineral deposit. Through R&D of various geological institutions, similar types of heavy minerals were identified in several river bars. A mineral processing plant has been set up at Beach Sand Minerals Exploitation Centre (BSMEC), Cox’s Bazar to identify the feasibility of commercial exploitation of those minerals. However, low physical grade, present market price and limited study on detail reserve of those minerals did not allow either government or private companies to undertake any commercial venture. Any feasible value addition to the quality and quantity is, therefore, necessary for viable commercial utilization of the identified minerals. Quantification of Beach placer deposits of Bangladesh are found to be radioactivity containing materials in several heavy minerals with specific presence of uranium and thorium.
Being the authority of managing radioactive materials in Bangladesh, BAEC has been continuing to quantify the uranium and thorium content in different placer minerals. The radioactivity measurements indicated contributions from Naturally Occurring Radioactive Materials (NORMs), such as thorium and uranium radioactive series and of 40K. The activity concentrations were found to be equivalent to maximum 37,600 ppm of thorium and 5,120 ppm of uranium. In separate other studies, the presence of 526-2557 ppm thorium and 140-1212 ppm uranium is reported in several fractions of processed zircon. Besides radioactive elements, monazite of Bangladesh is also characterized by the presence of various REEs, e.g. cerium, yttrium, lanthanum and neodymium. With an estimated reserve of over 160,000 tons of zircon and 17,000 tons of monazite in placers deposits at Bangladesh coast, the quantity of uranium and thorium could be significant. Similar REEs were identified in fluvial environments of Brahmaputra, Teesta and Jamuna. Results from multiple researches showed the presence of several rivers contain as high as 10% of heavy minerals, in which 0.35-0.96 wt% monazite is composed of total REEs of 121-184 ppm. Therefore, exploration for radioactive materials and REEs in placer sands would be a massive development in natural resource research in Bangladesh.
References: BSMEC, 1994; Ramesh et al., 2000; Zaman et al., 2012; Sasaki et al., 2015; Zaman et al., 2016; Rajib et al., 2016; Khalil et al., 2017; Deeba et al., 2019; Rajib et al., 2019; Hossain, 2019; Rajib and Oguchi, 2020; Aminur et al., 2021, 2020.