利用盐湖常见元素的助烧结作用绿色制备氧化镁及磷酸镁水泥

Green Preparation of Magnesia and Magnesium Phosphate Cement by Utilizing Common Elements in Salt Lake as Sintering Aid

低活性氧化镁是制备磷酸镁水泥(MPC)的关键原材料。现行低活性氧化镁的生产方式导致了制备MPC具有能耗高和成本高的缺点,不利于其推广应用。利用盐湖中常见元素如B,Na、K和Cl的助烧结作用,在≤1200℃煅烧盐湖提锂镁渣、外掺B的轻烧镁粉和水氯镁石的热解产物制备低活性氧化镁。介绍了低活性氧化镁的粒径、比表面积、孔隙率、化学组成、矿物组成和形貌等物理特征,以及低活性氧化镁制备MPC的凝结时间、水化产物、微观结构、抗压强度、体积稳定性等凝结硬化性能,并分析了烧结温度对低活性氧化镁的理化性能及MPC的凝结硬化性能的影响。相比现有技术,利用盐湖共存元素的助烧结作用可将氧化镁的烧结温度由1500~1800℃降低到1200℃以下,有利于实现低活性氧化镁及MPC的低能耗、低成本绿色制备,促进MPC的推广应用。

Low reactive magnesia is the key raw material for preparation magnesium phosphate cement(MPC).At present,MPC is difficult to popularize and apply mainly due to the high energy consumption and high cost for the preparation of low reactive magnesia.In this paper,the low reactive magnesia was prepared below 1200℃by sintering Mg-bearing tailing after extracting Li from Salt Lake,the light burnt magnesia mixed with boron,and the pyrolytic products of bischofite with the help of sintering aid namely common elements such as B,Na,K and Cl in salt lake.The physical characteristics of low active magnesia,such as particle size,specific surface area,porosity,chemical and mineralogical compositions,and morphology,as well as the setting and hardening properties of MPC,such as setting time,strength,volume stability,hydration product and microstructure,were introduced.The effects of sintering temperature on the physical and chemical properties of low reactive magnesia and the setting and hardening properties of MPC were analyzed.Compared with the existent technology,the sintering temperature of magnesia can be reduced from 1500℃to 1200℃by the sintering aid of coexisting elements in salt lake,which is conducive to preparation low reactive magnesia and MPC with low energy consumption and low cost as well as application of MPC.