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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
Author(s) -
Shen Zhuoxian,
Guan Baohong,
Fu Hailu,
Yang Liuchun
Publication year - 2009
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2009.03330.x
Subject(s) - chemistry , gypsum , flue gas desulfurization , potassium , sodium , dehydration , inorganic chemistry , tartrate , sodium sulfate , electrolyte , calcium , potassium sulfate , sodium citrate , nuclear chemistry , metallurgy , materials science , biochemistry , organic chemistry , medicine , electrode , pathology
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.