高压碱浸—常压酸浸法提纯鳞片石墨的研究

发布时间：2018-02-27 10:52

  本文关键词： 鳞片石墨 高压碱浸 常压酸浸 热力学 提纯　出处：《昆明理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：石墨由于其独特的晶体结构而具有许多优异的物理化学性能,高纯石墨作为石墨的深加工产品在高级密封、复合材料、核工业、航空航天等领域也大放异彩。本文首先对石墨的结构性质及石墨的应用进行了概述,指出目前一些重要工业部门快速发展和高品质石墨短缺的矛盾。总结了目前世界范围内的石墨提纯技术和工业生产状况,提出天然鳞片石墨精矿制备高品位石墨的研究方向,最终提出了本文的主要研究内容及研究意义。论文以青岛日来石墨有限公司提供的天然鳞片石墨精矿作为研究对象,研究了鳞片石墨中灰分杂质的赋存状态和脱灰过程的热力学,据其提出了高压碱浸联合常压酸浸法提纯石墨的技术路线,并对提纯过程的部分反应机理进行了理论分析。利用现代分析测试技术,分析了石墨中杂质元素的种类含量及物相组成。石墨中含有Si、Al、Fe、Mg等灰分元素,这些元素大部分以氧化物的形式存在。通过物相分析,了解到这些灰分元素的主要物相组成为游离石英(Quartz)、莫来石(Mullite)赤铁矿(Hematite)等。石墨中的矿物灰分颗粒夹杂分布于碳颗粒之间,还有一小部分浸染在碳基体中。这些杂质在物化性质上都有别于碳颗粒,简单的物理提纯方法难以使二者分离,化学浸出法更有利于石墨杂质的去除。探索石墨湿法提纯反应中的热力学规律,据此绘制了几种主要杂质元素水溶成分的lga-pH图,在不同温度时的Al-Si-H2O系的φ-pH图。从生产工艺上分析研究了氢氧化钠和硫酸的浓度、浸出温度,液固比、浸出时间等几种实验因素对石墨提纯的影响。初步确定了本试验的最佳工艺参数：高压碱浸：粒度300目；温度200℃; NaOH浓度15%；保温时间30min；液固比10：1；自蒸汽压2.1MPa；酸浸：粒度300目；温度90℃;H2SO4浓度12%；保温时间30min；液固比10：1。在上述最佳的工艺条件下提纯石墨,固定碳含量达到了98.71%,杂质含量为1.29%,杂质脱除率率超过93%,其中Si、Al去除率87%,Fe去除率90%,Ca脱除率95%,Na、Mg脱除率98%。
[Abstract]:Graphite has many excellent physical and chemical properties because of its unique crystal structure. High purity graphite is used as a deep processing product of graphite in advanced seal, composite material, nuclear industry, In this paper, the structure and properties of graphite and the application of graphite are summarized. This paper points out the contradiction between the rapid development of some important industrial departments and the shortage of high quality graphite, summarizes the present situation of purification technology and industrial production of graphite in the world, and puts forward the research direction of preparing high grade graphite from natural flake graphite concentrate. Finally, the main research contents and significance of this paper are put forward. The natural flake graphite concentrate provided by Qingdao Rilai Graphite Co., Ltd is taken as the research object. The existing state of ash impurities in flake graphite and the thermodynamics of ash removal process were studied. According to the thermodynamics, the technical route of purifying graphite by high pressure alkali leaching combined with atmospheric pressure acid leaching method was put forward. Some reaction mechanisms of the purification process were theoretically analyzed. By using modern analytical and testing techniques, the content of impurity elements and the phase composition of impurities in graphite were analyzed. Most of these elements exist in the form of oxides. By phase analysis, it is found that the main phases of these ash elements are free quartz quartzt, mullite hematite, etc. The mineral ash particles in graphite are distributed between carbon particles. There is also a small amount of soaking in carbon matrix. The physical and chemical properties of these impurities are different from those of carbon particles, and it is difficult to separate them by simple physical purification methods. The chemical leaching method is more favorable to the removal of graphite impurity. The thermodynamic law of graphite wet purification reaction is explored, and the lga-pH diagrams of several main impurity elements in aqueous solution are plotted accordingly. 蠁 -pH diagram of Al-Si-H2O system at different temperatures. The concentration of sodium hydroxide and sulfuric acid, leaching temperature, liquid-solid ratio were analyzed and studied. The effects of leaching time on graphite purification were preliminarily determined. The optimum technological parameters were determined as follows: high pressure alkali leaching: particle size 300 mesh; temperature 200 鈩，

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