CO_2海水脱钙后主要体系中镁盐的结晶  

Research on the crystallization process of magnesium salt in major system of decalcified seawater

作　　者：赵颖颖[1,2,3] 张焱[1,2] 邢贞干 纪志永[1,2,3] 王军[1,2,3] 袁俊生[1,2,3,4] ZHAO Yingying;ZHANG Yan;XING Zhenga;JI Zhiyong;WANG Jun;YUAN Junsheng(School of Marine Science and Engineering,Hebei University of Technology,Tianjin 300130,China;Engineering Research Center of Seawater Utilization Technology of Ministry of Education,Tianjin 300130,China;Modern Marine Chemical Collaborative Innovation Center of Hebei Province,Tianjin 300130,China;Quanzhou Normal University,Quanzhou 300130,Fujian,China)

机构地区：[1]河北工业大学海洋科学与工程学院,天津300130 [2]海水资源高效利用化工技术教育部工程研究中心,天津300130 [3]河北省现代海洋化工协同创新中心,天津300130 [4]泉州师范学院,福建泉州362000

出　　处：《化工进展》2017年第7期2400-2406,共7页Chemical Industry and Engineering Progress

基　　金：国家自然科学基金(21306037;21406051);国家科技支撑计划(2015BAB09B00);天津市自然科学基金(13JCQNJC05600;14JCYBJC20700);河北省高层次人才资助项目(C2013003041);河北省科技计划(14273105D);河北省自然科学基金(B2014202090)项目

摘　　要：使用烟道气中的二氧化碳进行海水脱钙后的体系中存在大量的镁离子和碳酸氢根离子。如果未加合理利用,不仅会造成资源的浪费,同时体系中存在的大量镁离子在后续生产过程中仍然会引起结垢的问题。本文提出通过使用氢氧化钠作为沉淀剂将该体系中的碳酸氢根转化为碳酸根,并与镁离子结合生成沉淀的新思路,继而减少了溶液中的碳酸氢根及镁离子,同时实现了镁资源和碳资源的进一步矿化利用。通过考察10℃、40℃和60℃条件下碱源中的OH~–与Mg^(2+)的摩尔比对镁提取率的影响,以及提镁后的固相的表征分析,得到了不同n(OH~–)/n(Mg^(2+))比值与固相沉积物的种类与形貌的对应关系。得出以下结论:随着NaOH加入量的增多,镁提取率增加;NaOH足够过量时,镁提取率会达到98%以上。在10℃下,镁系物能够以MgCO_3·3H_2O、Mg_5(CO_3)_4(OH)_2·5H_2O和Mg(OH)_2纯物质或混合物形式存在。60℃时MgCO_3·3H_2O消失,固相以Mg_5(CO_3)_4(OH)_2·4H_2O和Mg(OH)_2的纯物质或混合物形式存在。本研究为海水提镁、海水资源化利用及CO_2矿化技术提供了一个全新的思路和发展方向,为今后更深入地研究镁资源的提取工作提供了参考。There are a large number of magnesium ions and bicarbonate ions left in the system thatafter seawater decalcification using carbon dioxide,which can lead to scaling problem due to the lowsolubility of magnesium salts when the treated seawater is used.The new approach proposed in thisarticle is that bicarbonate ions are transformed to carbonate ions and combined with magnesium ionsby using sodium hydroxide as precipitant,which results in the further utilization of magnesiumresources and mineralization of carbon resources.The effect of mole ratio between hydroxyl ion in thealkali resource and magnesium ions on magnesium removal rates was investigated under the temperatureof10℃,40℃and60℃,respectively.The corresponding sediments were characterized by XRD and SEM.And the relationship between the value of n(OH–)/n(Mg2+)and the kinds and morphology of thesediment was obtained.The main conclusions are as follows:the magnesium removal rates increasedwith the increase of the amount of sodium hydroxide added,and the rates can reach over98%.At10℃,the precipitates existed in the form of pure MgCO3·3H2O,Mg5(CO3)4(OH)2·5H2O and Mg(OH)2or their mixtures.At40℃,MgCO3·3H2O disappeared,and the sediments were consist of pureMg5(CO3)4(OH)2·4H2O and Mg(OH)2or mixtures.This study provided a new approach for furtherutilization and mineralization of carbon dioxide of the decalcified seawater using flue gas,andprovided a reference for detailed research on the extraction of magnesium resources.

关 键 词：提镁 碳矿化 沉淀结晶 

分 类 号：TQ132.2[化学工程—无机化工]