Effect of trace metals on reactive crystallization of gypsum

✍ Scribed by Perviz Sayan; Sibel Titiz-Sargut; Burcu Avcı

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 401 KB
• Volume: 42
• Category: Article
• ISSN: 0232-1300
• DOI: 10.1002/crat.200710939

✦ Synopsis

Abstract

The effect of Fe^2+^, Fe^3+^, and Cr^3+^ ions on crystallization of calcium sulfate dihydrate (gypsum) produced by the reaction between calcium hydroxide suspension and sulphuric acid solution was investigated at 3.5 pH and 65°C in the absence and presence of 2500 ppm citric acid concentration. Crystal size distributions, filtration rates, and morphology of gypsum were determined and discussed as a function of ion concentration. Average particle size of gypsum was not affected significantly by the presence of Fe^2+^, Fe^3+^, and Cr^3+^ ions individually. Variation of gypsum morphology depending on ion concentration affected the filtration characteristics. The presence of Fe^3+^ or Cr^3+^ ions besides 2500 ppm citric acid influenced both average particle size and filtration characteristics. The effect of citric acid on gypsum morphology was suppressed at high Fe^3+^ and Cr^3+^ ion concentrations. The change of morphology is related to the complex formation between Fe^3+^ or Cr^3+^ ions and citric acid at high ion concentrations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)