Increasing the filtration rate of phospho-gypsum using surfactant

Effects of crystal habit modifiers on the morphology of calcium sulfate dihydrate grown in strong CaCl2‐HCl solutions

“…By controlling the reaction between CaCl 2 and H 2 SO 4 it is possible to favour the crystallization of calcium sulfate dihydrate (DH, CaSO 4 · 2H 2 O) or calcium sulfate α‐hemihydrate (α‐HH, CaSO 4 · 0.5H 2 O), depending on solution composition and temperature and at the same time achieve the regeneration of high strength hydrochloric acid . It is known that crystal size and morphology influence filtration rates, solid/liquid separation and washing operations that are critical in industrial crystallization . Furthermore, the morphology and purity of calcium sulfate crystals influence their end use as plaster material .…”

“…In cases where the additive concentration is below a certain threshold value that stops growth of one or more crystal faces, crystal morphology changes are induced. As a consequence this may result in improved filtration and particle size distribution characteristics . For example, it was shown by molecular simulations and experiments that citric acid adsorbs preferentially on the top faces of HH crystals, produced via the autoclave method, suspended in aqueous solution above 100 °C.…”

“…3 It is known that crystal size and morphology influence filtration rates, solid/liquid separation and washing operations that are critical in industrial crystallization. 4 Furthermore, the morphology and purity of calcium sulfate crystals influence their end use as plaster material. 5,6 Recently, we reported on impurity uptake and effects during crystallization of DH and α-HH in concentrated HCl-CaCl 2 solutions.…”

“…As a consequence this may result in improved filtration and particle size distribution characteristics. 4,9,12,17,30,32 For example, it was shown by molecular simulations and experiments that citric acid adsorbs preferentially on the top faces of HH crystals, produced via the autoclave method, suspended in aqueous solution above 100 • C. This resulted in compact prismatic crystals instead of elongated ones. 33 From the literature discussed above it becomes evident that there exists a wide range of additives that can influence the crystal morphology of calcium sulfates.…”

Crystallization study of reverse osmosis desalination scales at low salinity with and without inhibitor

“…Moreover, nucleation and crystal growth of calcium sulfate dihydrate using pure chemicals and under industrial simulated conditions of phosphoric acid production with and without additives such as crystal modifiers, promoters and inhibitors are also extensively studied by Abdel-Aal (1984), Abdel-Aal (1989), Abdel-Aal (2004) , Abdel-Aal et al (1998, Abdel-Aal, Rashad, and El-Shall (2004), Abdel-Aal et al (2007), El-Shall, Abdel-Aal, and Moudgil (1999), El-Shall, Moudgil, and Abdel-Aal (2000, El-Shall, Rashad, and Abdel-Aal (2002), El-Shall, Rashad, and Abdel-Aal (2005), Rashad, Baioumy, andAbdel-Aal (2003), Rashad et al (2004), Rashad et al (2005) and Mahmoud et al (2004). In addition, Abdel-Aal, Daosukho, andEl-Shall (2009), El-Shall et al (2004a) and El-Shall et al (2004b) studied nucleation and crystal growth of calcium oxalate monohydrate using pure chemicals with and without additives.…”