常压Mg-Na复合盐溶液体系制备α-半水石膏  

Preparation ofα-hemihydrate gypsum in Mg-Na mixed salt solution system under atmospheric pressure

作　　者：李云飞 刘蜀庆 唐盛伟[1] 张涛[1] LI Yunfei;LIU Shuqing;TANG Shengwei;ZHANG Tao(School of Chemical Engineering,Sichuan University,Chengdu 610065,China)

机构地区：[1]四川大学化学工程学院,四川成都610065

出　　处：《无机盐工业》2023年第11期100-106,共7页Inorganic Chemicals Industry

基　　金：国家重点研发计划“固废资源化”重点专项(2019YFC1905800)。

摘　　要：盐溶液的种类和浓度是常压盐溶液法制备α-半水石膏的关键因素。以Mg(NO_(3))_(2)为主体,考察了Mg(NO_(3))_(2)-Na Cl、Mg(NO_(3))_(2)-Na_(2)SO_(4)和Mg(NO_(3))_(2)-Na NO_(3)3种复合盐溶液体系中二水石膏向α-半水石膏转晶的过程,研究了Mg(NO_(3))_(2)-Na Cl体系中盐溶液浓度、转晶剂类型和用量对转晶速率和晶体形貌的影响。结果表明:在Mg(NO_(3))_(2)-1%Na Cl复合盐体系中4 h内将二水石膏全部转化为α-半水石膏的最低Mg(NO_(3))_(2)质量分数为27%;随着Mg(NO_(3))_(2)质量分数从27%增加至36%,溶液的过饱和度增大,二水石膏的转晶速率升高,诱导期从90 min减少至20 min;加入DL-苹果酸、顺丁烯二酸和3-硝基邻苯二甲酸转晶剂后,二水石膏转晶速率降低,产物长径比减小;在DL-苹果酸质量分数为1%条件下,α-半水石膏绝干抗压强度为21.74 MPa。The species and concentration of salt solution are the key factors of the preparation process ofα-hemihydrate gypsum in the atmospheric salt solution method.With Mg(NO_(3))_(2) as main composition,three kinds of mixed salt solution,in-cluding Mg(NO_(3))_(2)-NaCl、Mg(NO3)2-Na2SO4 and Mg(NO_(3))_(2)-NaNO_(3),were employed to investigate the crystal transforma-tion from dihydrate gypsum toα-hemihydrate gypsum,and the effects of the concentration of mixed salts,crystal modifier type and dosage on the transformation rate of dihydrate gypsum and crystal morphology were studied in the Mg(NO_(3))_(2)-NaCl solution.The results showed that in the mixed salt solution of Mg(NO_(3))_(2)-1%NaCl,the minimum Mg(NO_(3))_(2) mass fraction for the complete conversion of gypsum dihydrate to gypsum hemihydrate within 4 h was 27%.As the mass fraction of Mg(NO_(3))_(2) increasing from 27% to 36%,the supersaturation of the solution and transformation rate of dihydrate gypsum were in-creased,and the induction period was decreased from 90 min to 20 min.Using DL-malic acid,maleic acid and 3-nitroph-thalic acid as crystal modifiers,the transformation rate of dihydrate gypsum was decreased and the aspect ratio was reduced.When the mass fraction of DL-malic acid was 1%,the absolute dry compressive strength of theα-hemihydrate gypsum was 21.74 MPa.

关 键 词：半水石膏 常压盐溶液法 转晶剂 晶体形貌 力学性能 

分 类 号：TQ177.3[化学工程—硅酸盐工业]