Optimization of the Wet Mechanochemical Process Conditions of SrSO4 to SrCO3 and (NH4)2SO4 by Using Response Surface Methodology

The wet mechanochemical process was optimized for insoluble SrCO₃ and soluble (NH₄)₂SO₄ formation from celestite (SrSO₄)-(NH₄)₂CO₃-H₂O mixtures in a planetary ball mill by Box-Behnken design (BBD). The products formed during wet milling were analyzed with scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. For converting to SrCO₃ of celestite (SrSO₄) and to (NH₄)₂SO₄ of (NH₄)₂CO₃, a hydrometallurgical process optimization via the wet mechanochemical conversion using (NH₄)₂CO₃ was developed the first time in this work using response surface methodology. The wet mechanochemical conversion was carried out by varying ball to grinding material mass ratio, (NH₄)₂CO₃ to SrSO₄ mole ratio and the rotational speed of mill in a planetary mill. Under the optimum experimental conditions (9.24 of ball to grinding material mass ratio, 1.86 of (NH₄)₂CO₃ to SrSO₄ mole ratio and 400 rpm of the rotational speed of mill), the conversion of SrCO₃ was 99.08 pct. The (NH₄)₂SO₄ obtained as byproduct was crystallized.