A simple method is developed for the separation and recovery of uranium in a CaF₂ and MgF₂ matrix, employing a solid state reaction route, heating the uranium slagcomposition mixture with (NH₄)₂SO₄. Reactions of a synthetic slagcomposition mixture with (NH₄)₂SO₄ above 350 °C formed sulfate compounds of uranium, calcium and magnesium. The sulfates of uranium were separated by dissolving in dilute acid. Reactions were monitored by TG-DTA analysis. Products formed at different temperatures were characterised by X-ray powder diffraction. Quantitative analysis of the products was achieved using redox titrimetry. By this method about 95% of the uranium present could be recovered from synthetic mixtures.