Natural radioactivity and the associated radiation hazardous in primary phosphate materials and fertilizer products

The radioactivity concentrations of the natural radionuclides namely 2238U, 226Ra, 232Th, and 40K in 20 samples from the initial raw material and the by-products of triple phosphate fertilizer industry have been determined using a gamma ray spectroscopic system (HPGe-detector) and the related radiation hazardous were calculated. The mean values of the radioactivity levels obtained for the radionuclides in phosphate rocks were found 2766, 1329, 18.1 and 151 Bq/kg for 226Ra, 232Th, and 40K, respectively. The mean values in phosphogypsum were, 898, 429, 22 and 97 Bq/kg and inn triple phosphate fertilizer were 492, 6811, 31.8 and 36.4 Bq/kg, respectively. But in case of phosphoric acid they were 175, 352, 45.22 and 5.1 Bq/1, respectively. The calculated dose rate (n Gy h-1) in test samples was more than the average permissible world value (57 n Gy h-1) due to the increase of the radium activity concentrations in test samples. Increases of the gamma dose rate lead to increase of the absorbed dose for the workers in both the phosphate fertilizers production and agriculture fields which use this kind of fertilizers