摘要:
以菱镁矿为原料,先合成MgCO3·3H2O晶须,并以此为前驱体,制备了高纯414型碱式碳酸镁,主要研究机械搅拌作用对结晶过程的影响.利用X射线衍射(XRD)和扫描电镜(SEM)分析了碱式碳酸镁物相组成及微观形貌.结果表明,搅拌有助于加快相转变进程,热解温度70℃,搅拌作用下,60min时,MgCO3·3H2O全部转变为形貌均匀的多孔棒状4MgCO3·Mg(OH)2·4H2O;而无搅拌作用下,90min时MgCO3·3H2O全部转变为多孔玫瑰花状4MgCO3·Mg(OH)2·4H2O微球.4MgCO3·Mg(OH)2·4H2O晶体中,Mg2+呈现两种不同的正八面体配位,MgO6正八面体通过共顶点和共棱的方式连接而成,分别沿[100]和[001]方向快速生长,最终形成球状或棒状形貌.
关键词:
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菱镁矿
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碱式碳酸镁
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三水碳酸镁
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搅拌
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制备
Abstract:
Taking magnesite ore as raw materials, MgCO3·3H2O whiskers were synthesized and used as precursors of high pure 414 type alkaline magnesium carbonate.The influence of mechanical agitation on crystalline process was investigated.The phase composition and microtopography of the produced samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM).The results showed that the agitation contributed to accelerate the phase transition of MgCO3·3H2O.After stirring at 70 ° C for 60 minutes, MgCO3·3H2O completely transformed into uniform porous rod-like 4MgCO3·Mg(OH)2·4H2O.While MgCO3·3H2O would completely transformed into porous rosette-like 4MgCO3·Mg(OH)2·4H2O microspheres after 90 minutes without stirring.For hydromagnesite crystal, [MgO6] octahedrons were connected with common point and edge, and Mg2+ presented two different octahedral coordination.The two different [MgO6] octahedrons grew along the [100] and [001] direction, leading to the formation of spherical and rod-like morphologies, respectively.
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