<p>Phosphogypsum (PG), a byproduct of wet-process phosphoric acid production, has accumulated in vast quantities worldwide. Most of this material is stacked in open areas, raising significant environmental concerns due to its residual radioactivity and chemical impurities, which limit its reuse. This research found that the majority of radioactivity in a Florida PG sample was concentrated in the micro-fine fraction (− 400 mesh) and the coarse fraction (+ 35 mesh). In contrast, the intermediate size fractions (20 to 400 mesh) exhibited lower radioactivity levels, meeting the U.S. Environmental Protection Agency (EPA) civil use threshold of less than 10 pCi/g. Moreover, a clear inverse relationship was observed between gypsum content and radioactivity—the higher the gypsum purity, the lower the radiation level. Conventional flotation methods for gypsum separation, which operate in neutral or weakly alkaline conditions, require large amounts of alkalis to neutralize the acidic pulp, resulting in prohibitively high costs. In this study, an alternative flotation process was developed that operates directly in acidic pulp, using sulfuric acid to adjust pH and an amine as the collector. At an optimized pulp pH of approximately 1.44, the flotation concentrate achieved a gypsum grade of 93%–94%, with recovery rates up to 94%. Importantly, the sulfuric acid used for pH adjustment can be reused with the process water, significantly reducing reagent consumption and overall processing costs compared to conventional neutral or alkaline flotation techniques.</p>