Phosphogypsum is a byproduct from the phosphoric acid industry which is formed by crystallisation during sulfuric acid attack on phosphate rocks. While the composition of phosphogypsum is dihydrated calcium sulphate, the material can contain high levels of impurities that exist in phosphate rocks, such as radionuclides from the 238U and 232Th series. The most common way of disposing of phosphogypsum is in piles in the environment around a phosphate ore processing plant. This could represent a risk to air, soil, and water, since this material has considerable 238U and 232Th radionuclide activities and their decay products.
Keywords: phosphogypsum, radionuclides, uranium, thorium, neutronic activation, arsenazo III, alpha spectrometry, environmental pollution