Radiological and chemical assessment of phosphate rocks in some countries

In this study, the radiological, structural and chemical characterizations of Mardin-Mazidagi phosphate rock, which is an important phosphate fertilizer source in Turkey were investigated and compared to those of several different phosphate rocks of Tunisia, Egypt, Morocco, Algeria and Syria using gamma spectrometry, X-ray diffraction (XRD) and X-ray fluorescence (XRF) measurement techniques. Elemental analysis results of phosphate samples showed that they were mainly composed of CaO, P2O5, SiO2, Al2O3, SO3 and Fe2O3. Elemental concentrations of U and Th were calculated using Ra-226 and Th-232 activity concentrations, respectively. As a result of XRD analysis, the main peaks of the samples were found to be, Fluorapatite (Ca-5(PO4)(3)F). The radioactivity concentration levels for Ra-226, Th-232 and K-40 in all phosphate samples ranged from 250 to 1029 Bq kg(-1) with a mean of 535 Bq kg(-1), from 5 to 50 Bq kg(-1) with a mean of 20 Bq kg(-1) and from 117 to 186 Bq kg(-1) with a mean of 148 Bq kg(-1), respectively. The computed values of annual effective doses ranged from 0.17 to 0.59 mSv, with a mean value of 0.33 mSv, which is lower than the recommended limit of 1 mSv y(-1) by the International Commission on Radiological Protection. (C) 2010 Elsevier B.V. All rights reserved.