常压无氯复合盐溶液磷石膏制备α-半水石膏
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摘要
目前常压盐溶液法实现磷石膏到α-半水石膏转化主要采用氯盐体系,存在产物含氯量高,含氯废水难以处理的问题。本研究以Ca(NO3)2-Na2SO4复合盐溶液作为传统氯盐溶液的替代介质,同时为了避免单一盐溶液中有机转晶剂引起的延缓效应。结果表明:在95℃,55%Ca(NO3)2,0.1%丁二酸,磷石膏料浆质量分数20%的条件下,反应6 h,磷石膏能够转化成短柱状,长径比约接近1∶1的α-半水石膏。与单一Ca(NO3)2盐溶液相比,采用Ca(NO3)2-Na2SO4复合盐溶液能够缩短磷石膏脱水反应时间,消除有机酸的延缓效应,提高磷石膏的转换效率。
At present, the phase transformation of phosphogypsum(PG) to α-calcium sulfate hemihydratev salt solution method under atmospheric pressure usually adopts chloride salt system, which has the problems of high chloride content in products and difficult treatment of chloride-containing wastewater. In this study, Ca(NO_3)_2-Na_2SO_4 complex salt solution was used as a substitute system for traditional chloride solution,and in order to avoid the retarding effect caused by organic morphology modifier in single salt solution.The results indicate that PG can be successfully transformed into α-CSH which is short column with a aspect ratio about 1.0 under the conditions of 95 ℃, 55% Ca(NO_3)_2, 0.1% succinic acid and 20%PG slurry concentration for 6 h. Compared with single Ca(NO_3)_2 salt solution, Ca(NO_3)_2-Na_2SO_4 complex salt solution can eliminate the retarding effect caused by organic acid, and result in a shorter dehydration reaction time of PG as well as a higher transformation efficiency.
At present, the phase transformation of phosphogypsum(PG) to α-calcium sulfate hemihydratev salt solution method under atmospheric pressure usually adopts chloride salt system, which has the problems of high chloride content in products and difficult treatment of chloride-containing wastewater. In this study, Ca(NO_3)_2-Na_2SO_4 complex salt solution was used as a substitute system for traditional chloride solution,and in order to avoid the retarding effect caused by organic morphology modifier in single salt solution.The results indicate that PG can be successfully transformed into α-CSH which is short column with a aspect ratio about 1.0 under the conditions of 95 ℃, 55% Ca(NO_3)_2, 0.1% succinic acid and 20%PG slurry concentration for 6 h. Compared with single Ca(NO_3)_2 salt solution, Ca(NO_3)_2-Na_2SO_4 complex salt solution can eliminate the retarding effect caused by organic acid, and result in a shorter dehydration reaction time of PG as well as a higher transformation efficiency.
引文
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[10]彭家惠,瞿金东,张建新,等.丁二酸对α半水脱硫石膏晶体生长习性与晶体形貌的影响[J].东南大学学报(自然科学版),2011,41(6):1307-1312.
[11]GUAN B,SHEN Z,WU Z,et al.Effect of pH on the Preparation ofα-Calcium Sulfate Hemihydrate from FGD Gypsum with the Hydrothermal Method[J].Journal of the American Ceramic Society,2008,91(12):3835-3840.
[12]ZüRZ A,ODLER I,THIEMANN F,et al.Autoclave-Free Formation ofα-Hemihydrate Gypsum[J].Journal of the American Ceramic Society,1991,74(5):1117-1124.
[2]TAYIBI H,CHOURA M,LOPEZ F A,et al.Environmental impact and management of phosphogypsum[J].Journal of environmental management,2009,90(8):2377-2386.
[3]OTHMAN I,AL-MASRI M S.Impact of phosphate industry on the environment:a case study[J].Applied Radiation and Isotopes,2007,65(1):131-141.
[4]YANG J C,WU H D,TENG N C,et al.Novel attempts for the synthesis of calcium sulfate hydrates in calcium chloride solutions under atmospheric conditions[J].Ceramics International,2012,38(1):381-387.
[5]WOO K M,JUNG H M,OH J H,et al.Synergistic effects of dimethyloxalylglycine and butyrate incorporated intoα-calcium sulfate on bone regeneration[J].Biomaterials,2015,39:1-14.
[6]马保国,茹晓红,邹开波,等.常压水热Ca-Na-Cl溶液中用磷石膏制备α-半水石膏[J].化工学报,2013,64(7):2701-2707.
[7]JIANG G,WANG H,CHEN Q,et al.Preparation of alpha-calcium sulfate hemihydrate from FGD gypsum in chloride-free Ca(NO3)2solution under mild conditions[J].Fuel,2016,174:235-241.
[8]LIU S,SUN H,SUN L,et al.Effects of pH and Cl-concentration on corrosion behavior of the galvanized steel in simulated rust layer solution[J].Corrosion Science,2012,65:520-527.
[9]沈卓贤.脱硫石膏在常压盐溶液中制备α-半水石膏的转晶剂作用研究[D].杭州:浙江大学,2008.
[10]彭家惠,瞿金东,张建新,等.丁二酸对α半水脱硫石膏晶体生长习性与晶体形貌的影响[J].东南大学学报(自然科学版),2011,41(6):1307-1312.
[11]GUAN B,SHEN Z,WU Z,et al.Effect of pH on the Preparation ofα-Calcium Sulfate Hemihydrate from FGD Gypsum with the Hydrothermal Method[J].Journal of the American Ceramic Society,2008,91(12):3835-3840.
[12]ZüRZ A,ODLER I,THIEMANN F,et al.Autoclave-Free Formation ofα-Hemihydrate Gypsum[J].Journal of the American Ceramic Society,1991,74(5):1117-1124.