Effect of Salt on the Formation of <TEX>$alpha$</TEX>-Calcium Sulfate Hemihydrate from by-Product Gypsum of Phosphoric Acid Process in Aqueous Salt Solution at Atmospheric Pressure

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J. Korean Ceram. Soc. > Volume 25(1); 1988 > Article

Journal of the Korean Ceramic Society 1988;25(1): 66.

상압수용액중에서 인산석고로부터 $alpha$형 반수석고의 생성에 미치는 염류의 영향

이구종, 최상흘¹

국립공업시험언 요업과
¹한양대학교 무기재료공학과

Effect of Salt on the Formation of $alpha$-Calcium Sulfate Hemihydrate from by-Product Gypsum of Phosphoric Acid Process in Aqueous Salt Solution at Atmospheric Pressure

ABSTRACT

The effect of salts on the formation of ${alpha}$-hemihydrated gypsum at boiling temperature under atmospheric pressure was studied by the solubility measurement method, and the formation of ${alpha}$-hemihydrated gypsum from by-product gypsum of phosphoric acid process in the salts solution were investigated. The order of catalytic effect of salt on the formation of ${alpha}$-hemihydrated gypsum are as follows: NH4Cl>NaCl>NaNO3. In the salts solution of sodium nitrate, sodium chloride, and ammonium chloride, prismatic ${alpha}$-hemihydrated gypsum was obtained and the crystal form was converted to needle form in complex solution with sulfuric acid. The P2O5 content in gypsum was largely decreased in this atmosphoric solution process.