水化方式对微晶菱镁矿制备高纯氢氧化镁的影响  

Effect of hydration process on preparation of high purity magnesium hydroxide from microcrystalline magnesite

作　　者：李志勋 冯润棠 田晓利 金汝 Li Zhixu;;Feng Runtang;Tian Xiaoli;Jin Ru(Puyang Refractories Group Co.,Ltd.,Puyang 457100,Henan,China)

机构地区：[1]濮阳濮耐高温材料(集团)股份有限公司,河南濮阳457100 [2]西安建筑科技大学材料与矿资学院,陕西西安710055

出　　处：《耐火材料》2018年第3期213-216,共4页Refractories

摘　　要：为了利用我国川藏地区的微晶菱镁矿制备高纯氢氧化镁,将20~3 mm的微晶菱镁矿经900℃保温3 h轻烧后磨至≤0.1 mm,再分别经过25℃常温水化、95℃高温水浴水化和高压(1 MPa)蒸汽水化(又分为干蒸和湿蒸两种)除杂而得到高纯氢氧化镁,并对水化产物进行化学组成分析、水化率(经500℃保温2 h煅烧)检测、激光粒度分析、XRD分析及显微形貌观察。结果表明:常温及高温水化的水化率分别为74.5%、82.1%,产物为氢氧化镁及部分未水化的氧化镁,常温水化的产物呈颗粒状,晶粒较小;高温水化的产物呈片状且团聚明显。高压蒸汽水化的产物的水化率≥95.2%,得到的氢氧化镁粒度小,分散性好;干蒸水化的产物呈六方片状及颗粒状,而湿蒸水化的产物较干蒸具有更好的结晶形态,呈六方片状。化学分析结果表明,采用不同水化方式得到的产物,经500℃保温2 h去除灼减后的Mg O含量均在99%(w)左右,说明用该微晶菱镁矿可制备出高纯度的氢氧化镁。In order to prepare high purity magnesium hydroxide using microcrystalline magnesite from Sichuan and Tibet regions,the specimens were prepared using 20-3 mm microcrystalline magnesite,firing at 900 ℃ for 3 h,milling to ≤0. 1 mm,and hydrating at ambient temperature 25 ℃,in 95 ℃ water bath,and under high pressure（1 MPa） steam（dry or wet evaporation） respectively,for removing impurities. The chemical composition analysis, hydration rate determination（calcining at 500 ℃ for 2 h）,laser grain size analysis,XRD analysis,and microstructure observation of the hydration products were carried out. The results show that the hydration rate at ambient and high temperatures is 74. 5% and 82. 1%,respectively; the products are magnesium hydroxide and some unhydrated Mg O; the products hydrated at ambient temperature are particles with small crystalline grains,the products hydrated at high temperature are flake-like and flocculate obviously. The hydration rate of the products under high pressure steam is ≥95. 2%,and the products are featured with small particle and good dispersity. The products hydrated by dry evaporation are hexagonal flake-like particles,and have worse crystal pattern than wet evaporation ones,which are hexagonal flake-like. The chemical analysis results show that after being fired at 500 ℃ for 2 h,the hydration products gained by different methods have the same MgO content（about 99%） by reducing the loss on ignition,meaning that the microcrystalline magnesite can be used to prepare high purity magnesium hydroxide.

关 键 词：微晶菱镁矿 氢氧化镁 轻烧MgO 高温水浴水化 高压蒸汽水化 除杂 六方片状 

分 类 号：TQ175[化学工程—硅酸盐工业]