杂质离子对冷析结晶硫酸镁形貌影响的规律研究  

Regular study on effect of impurity ions in brine on morphology of magnesium sulfate crystallized by halogenation-cold precipitation

作　　者：杨敏航 徐楷 成怀刚 程文婷 宋慧平 YANG Minhang;XU Kai;CHENG Huaigang;CHENG Wenting;SONG Huiping(Institute of Resources and Environmental Eneineering,Engineering Research Center of Resource Efficiency Enhancing and Carbon Emission Reduction in Yellow River Basin,Ministry of Education of the People′s Republic of China,Taiyuan 030032,China;Qinghai university school of chemical engineering,Xining 810016,China;Shanxi yellow river laboratory,Taiyuan 030032,China)

机构地区：[1]山西大学资源与环境工程研究所,黄河流域资源增效减碳教育部工程研究中心,山西太原030032 [2]青海大学化工学院,青海西宁810016 [3]山西省黄河实验室,山西太原030032

出　　处：《无机盐工业》2025年第4期22-30,共9页Inorganic Chemicals Industry

基　　金：国家自然科学基金项目[U20A20149];青海省基础研究计划项目[2023-ZJ-920M];国家自然科学基金项目[22208198、22378241];青海省昆仑英才·高端创新创业人才项目(2021)。

摘　　要：冷析结晶是生产结晶硫酸镁的常用方法之一,但得到的硫酸镁晶体往往形貌不规则且表面粗糙,限制了硫酸镁晶体在涂层、复合材料等领域的应用。针对原料卤水中常见离子Li^(+)、K^(+)、Ca^(2+)对结晶硫酸镁微观形貌的影响开展研究,以更好地满足后续应用的需要。根据冷析法提取高纯硫酸镁水合物工艺,在MgSO_(4)-NaCl共饱和溶液的静置结晶中,对介稳态溶液及结晶产物进行表征。结果表明,降温过程中NaCl会附着在结晶表面影响晶体形貌。杂质离子会提高溶剂共享型离子对(Mg^(2+)-H_(2)O-SO_(4)^(2-))的比例,使其更有利于MgSO_(4)·6H_(2)O的生长和析出;不改变降温结晶产物组成的同时,杂质离子会促使晶体表面Na含量降低,优化晶体形貌;当K_(2)SO_(4)浓度为300 mmol/L时,产品中Na质量分数可从0.57%降低至0.03%,得到规整的结晶产物。推测杂质离子会与Na^(+)竞争位于晶体表面的结晶位点,阻止钠盐成核,并采用分子动力学模拟验证了上述推测。因此,溶液中少量杂质离子的存在有助于获得表面光滑、性质稳定的硫酸镁晶体。Cold precipitation crystallization is one of the common methods to produce crystalline magnesium sulfate,but the obtained magnesium sulfate crystals often have irregular morphology and rough surface,which limits the application of mag-nesium sulfate crystals in the field of coatings and composites.In this paper,the effect of common ions Li^(+)、K^(+)、Ca^(2+)in raw brine on the micro-morphology of crystallized magnesium sulfate was studied to better meet the needs of subsequent applications.According to the process of extracting high-purity magnesium sulfate hydrate by cold precipitation method,the mesostable solution and crystalline products were characterized in the static crystallization of MgSO_(4)-NaCl co-saturated solution.The results showed that NaCl was adhered to the crystalline surface during the cooling process affecting the crystal morphology.The impurity ions would increase the ratio of solvent-sharing ion pairs(Mg^(2+)-H_(2)O-SO_(4)^(2-)),which was more favorable for the growth and precipitation of MgSO_(4)·6H_(2)O.While the composition of the cooling crystallization products was not changed,the impurity ions would contribute to the reduction of Na content on the crystal surface and optimize the crystal morphology.When the content of K_(2)SO_(4)was 300 mmol/L,the Na content of the products could be reduced from 0.57%to 0.03%,and a regular crystalline product was obtained.It was hypothesized that the impurity ions would compete with Na^(+)for the crystalli-zation sites located on the crystal surface,preventing the nucleation of the sodium salt,and molecular dynamics simulations were used to verify the above speculation.Therefore,the presence of a small amount of impurity ions in solution was condu-cive to to obtain magnesium sulfate crystals with smooth surface and stable properties.

关 键 词：硫酸镁 冷析结晶 微观形貌 杂质离子 

分 类 号：TQ132.2[化学工程—无机化工]