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- Title
Effect of Potassium Sodium Tartrate and Sodium Citrate on the Preparation of α-Calcium Sulfate Hemihydrate from Flue Gas Desulfurization Gypsum in a Concentrated Electrolyte Solution.
- Authors
Zhuoxian Shen; Baohong Guan; Hailu Fu; Liuchun Yang
- Abstract
Flue gas desulfurization (FGD) gypsum mainly composed of calcium sulfate dihydrate (DH) was used as a raw material to obtain α-calcium sulfate hemihydrate (α-HH) through dehydration in a Ca–Mg–K–Cl-solution medium at 95°C under atmospheric pressure. The effects of potassium sodium tartrate and sodium citrate on the preparation of α-HH in the electrolyte solution were investigated. The results revealed that the addition of potassium sodium tartrate (1.0 × 10−2–2.5 × 10−2 M) decreased the dehydration rate of FGD gypsum and increased the length/width ( l/w) ratio of α-HH crystals, which could yield unfavorable strength properties. Addition of sodium citrate (1.0 × 10−5– 2.0 × 10−5 M) slightly increased the dehydration rate of FGD gypsum and decreased the l/w ratio of α-HH crystals, which could be beneficial to increase strength. However, it also led to a partial formation of anhydrite (AH) crystals. AH was also the only dehydration product when the concentration of sodium citrate increased to 1.0 × 10−4 M. Therefore, sodium citrate rather than potassium sodium tartrate could be used as an additive in Ca–Mg–K–Cl electrolyte solutions if α-HH with a shorter l/w ratio is the desired product from FGD gypsum dehydration. The concentration of sodium citrate should be properly controlled to reduce the formation of AH.
- Subjects
ELECTROLYTE solutions; ELECTROLYTES; FLUE gases; CRYSTALS; GYPSUM; SOLUTION (Chemistry); ANHYDRITE; SULFATE minerals
- Publication
Journal of the American Ceramic Society, 2009, Vol 92, Issue 12, p2894
- ISSN
0002-7820
- Publication type
Article
- DOI
10.1111/j.1551-2916.2009.03330.x