Natural radionuclides in the aquatic environment of a phosphogypsum disposal area

Rock phosphate ore processing and disposal of phosphogypsum contribute to enhanced levels of natural radionuclides in the environment. Studies on the distribution of U-series nuclides were carried out in the Chitrapuzha River, near Cochin, in the southern part of India. The concentrations of radionuclides, especially 226Ra, in the river waters showed enhancement by an order of magnitude relative to the levels in nearby water bodies. The concentrations were influenced by seasonal changes in the river flows during monsoon and summer periods. Ingestion doses via fish and milk have an upper estimate of 18 microSv for the critical population.     

Immobilisation of beryllium in solid waste (red-mud) by fixation and vitrification

The objective of this study was to obtain information on the immobilization of beryllium (Be) in solid waste generated in the extraction process of beryllium from its ore, Beryl. This solid waste, termed red-mud, contains oxides of iron, aluminium, calcium, magnesium and beryllium. The red-mud waste contains beryllium at levels above the permissible limit, which prevents its disposal as solid waste. The total beryllium content in the red-mud analysed showed value ranging from 0.39 to 0.59% Be The studies showed that 50% of the total beryllium in red-mud can be extracted by water by repeated leaching over a period of 45 days. The cement mix, casting into cement blocks, was subjected to leachability studies over a period of 105 days and immobilization factor (IF factor) was determined. These IF values, of the order of 102, were compared with those obtained by performing leachability study on vitrified red-mud masses produced at different temperature conditions. Direct heating of the red-mud gave the gray coloured, non-transparent vitreous mass (as 'bad glass') showed effective immobilisation factor for beryllium in red-mud of the order of 10(4).