焙烧-水化络合法脱除镁废渣中钙杂质的研究  

Study on removal of calcium impurities from magnesium waste residue by roasting-hydration complexing

作　　者：曾彦捷 徐同飞 黄子良 陈志鹏 刘旭东 易美桂[1] ZENG Yanjie;XU Tongfei;HUANG Ziliang;CHEN Zhipeng;LIU Xudong;YI Meigui(School of Chemical Engineering,Sichuan University,Chengdu 610065,China;Panzhihua Iron and Steel Group Sponge Titanium Branch;Chengdu Changnong Technology Co.,Ltd.)

机构地区：[1]四川大学化学工程学院,四川成都610065 [2]攀钢集团海绵钛分公司 [3]成都昌农科技有限公司

出　　处：《无机盐工业》2022年第11期118-123,共6页Inorganic Chemicals Industry

摘　　要：以含钙镁废渣为原料,采用高温焙烧-EDTA络合法脱除其中的钙杂质制备高纯氧化镁,探究了焙烧温度与时间、EDTA溶液浓度、络合温度、液固质量比与水化时间对钙杂质脱除效果的影响。利用X射线衍射(XRD)、X射线光电子能谱(XPS)等方法对样品结构进行表征。结果表明,镁废渣中钙、镁分别以碳酸钙(CaCO_(3))和碱式碳酸镁[4MgCO_(3)·Mg(OH)_(2)·4H_(2)O]形式存在,经过高温焙烧过程分别分解为氧化钙(CaO)和氧化镁(MgO)。热力学计算表明,体系中钙、镁离子与EDTA的络合能力存在较大差异,EDTA与钙离子络合能力强,与镁离子络合能力极弱,络合作用促进CaO溶解,使钙离子进入液相,MgO停留在固相,实现钙、镁分离。在800℃、0.5 h、c(EDTA)=0.01 mol/L、液固质量比为80∶1、常温水化时间为2.0 h时,钙脱除率达到98.78%,产物经105℃烘干8.0 h,MgO纯度大于99.00%。The high-purity magnesium oxide was prepared from calcium-magnesium-containing waste residue as raw materials by the high-temperature roasting-EDTA complexing method to remove calcium impurities.The effects of calcination temperature and time,molar concentration of EDTA solution,complexation temperature,liquid solid ratio and hydration time on removal of calcium impurities were investigated.The structure of the product was characterized by means of X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and other methods.The results showed that calcium and magnesium were existed in the form of CaCO_(3)and 4MgCO_(3)·Mg(OH)_(2)·4H_(2)O in the magnesium waste residue and decomposed into CaO and MgO after high temperature roasting,respectively.Thermodynamic calculation showed that the complexing ability of calcium,magnesium ions,and EDTA in the system was quite different.EDTA had a strong complexing ability with Ca^(2+),but very weak with Mg^(2+).The complexation promoted the dissolution of CaO and made Ca^(2+)enter the liquid phase.MgO was stayed in the solid phase to enable calcium separate from magnesium.At 800℃,0.5 h,c(EDTA)=0.01 mol/L,liquid solid ratio of 80∶1 and hydration at room temperature for 2.0 h,the calcium removal rate reached 98.78%.When the product was dried at 105℃for 8.0 h,the purity of MgO was greater than 99.00%.

关 键 词：镁废渣 高温焙烧-EDTA络合 氧化钙 氧化镁 

分 类 号：X781[环境科学与工程—环境工程]