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

Journal of the American Ceramic Society - Tập 92 Số 12 - Trang 2894-2899 - 2009
Zhuoxian Shen1, Baohong Guan1, Hailu Fu1, L. C. Yang1
1Department of Environmental Engineering, Zhejiang University, Hangzhou 310027, China

Tóm tắt

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 × 10−2M) 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 × 10−5M) 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 × 10−4M. 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.

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Thông tin xuất bản

Journal of the American Ceramic Society

Tập 92 Số 12

2894-2899

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