Fluorine Quantification in Phosphogypsum by Particle Induced γ-Ray Emission

Phosphogypsum (PG) is the main by-product of the wet processing of phosphate rock for phosphoric acid production and is generated worldwide in hundreds of millions of tons per year. With an increasing demand for gypsum-based materials for industrial and agricultural applications and the predictable gypsum shortage in the coming years, PG can be considered a valuable replacement. However, the presence of fluorine in PG can limit its use, given the negative effects it can have on human health and the environment. In this work, it is presented a new methodology which determines with high sensitivity the fluorine concentrations in PG by a combination of Ion Beam Analytical (IBA) techniques, with a focus on PIGE (Particle Induced γ-ray Emission). Seventeen PG samples were analyzed, fifteen of which originated from processing experiments. Fluorine was detected in concentrations ranging from 0.003 to 0.691 wt.%. The upper end of this range is comparable to or higher than typical values reported for PG and may require treatment depending on the intended end use and environmental compliance criteria.