Influence of Na₂SO₄ Produced from Phosphogypsum Conversions on the Basic Properties of Building Gypsum

This study comprises two distinct but interrelated parts. The first part involves optimizing the conditions for the conversion of phosphogypsum to a Ca(OH)₂ and Na₂SO₄ solution. The second part focuses on enhancing the mechanical properties of gypsum through the use of a sodium sulphate additive derived from the conversion of phosphogypsum. An ultrasonic disperser was employed to accelerate the reaction between phosphogypsum and a sodium hydroxide solution. The mean dispersion time was found to be 0.2, 0.5, 1.0, and 2.0 min. The resulting product was a solution of calcium hydroxide and sodium sulfate. The impact of varying quantities of Na₂SO₄ on the compressive strength and density of building gypsum samples was investigated. An increase in the quantity of sodium sulphate from 0.2% to 2% resulted in a notable rise in the density of the building gypsum samples, from 1127 kg/m³ in the reference sample to 1264 kg/m³ in the sample containing 2% sodium sulphate. Therefore, in all instances, the utilization of the Na₂SO₄ additive in the gypsum samples resulted in elevated compressive strengths (4.8-8.6 MPa) in comparison to the reference sample devoid of this additive (1.6 MPa).