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

Abstract

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.