莫来石和刚玉—莫来石复相耐火原料的合成及应用性能研究
发布时间：2019-06-22 09:07
【摘要】：我国高铝矾土资源日益匮乏,尤其是高品位的铝矾土矿,并且存在大量的碎矿和中低品位矿被闲置或浪费、烧成后的高铝矾土熟料质量稳定性差、烧成工艺落后、污染环境严重等问题。面对这些问题,如何能够综合利用低品位矿制备出致密度高、质量稳定性好的矾土熟料成为研究的热点。本文采用“成分设计准确,湿法细磨,湿法成型,高温烧成”的新型湿法均化工艺制备不同等级的矾土基均质料,这种先进的生产工艺不仅可以将矾土矿开采过程中产生的渣料、边角料、碎矿、粉矿以及中低品位的铝矾土得到充分利用,还可以解决矾土矿在开采过程中所造成的环境污染和资源浪费的问题,从而实现铝土矿资源的可持续发展。本论文采用湿法均化工艺,将氧化铝含量约为63wt%、67wt%、73wt%和75wt%的生坯,高温煅烧为氧化铝含量分别为70wt%、75wt%、85wt%、88wt%的矾土基均质料,其中氧化铝含量分别为70wt%和75wt%的矾土基均质料(分别简称为JZ-70料和JZ-75料)统称为均质莫来石原料,氧化铝含量分别为85wt%和88wt%的矾土基均质料(分别简称为JZ-85料和JZ-88料)统称为均质刚玉-莫来石原料。测试不同烧成工艺下均质莫来石原料和均质刚玉-莫来石原料的重烧线变化率、失重率、体积密度和显气孔率等性能,确定不同品级矾土级均质料的烧成工艺。研究均质莫来石原料和均质刚玉-莫来石原料的烧结机理,对烧结过程的动力学进行分析,并将实验获得均质莫来石原料和均质刚玉-莫来石原料进行应用研究。结论如下:均质莫来石JZ-70料和JZ-75料的最佳烧成制度为1600℃保温4h,得到JZ-70料的体积密度为2.82g.cm-3,显气孔率8.42%;JZ-75料的体积密度为2.93g·cm-3,显气孔率3.52%,与SK-70料(SK代表生矿)和SK-75料的体积密度基本一致。SK-70料的显微结构图中明显分为两种不同的区域,而JZ-70 料内部原高岭石和水铝石的聚集体已经消失,二次莫来石化更为彻底。均质刚玉-莫来石JZ-85料和JZ-88料的最佳烧成制度为1600℃保温7h,此时JZ-85料的体积密度为3.3g·cm-3,显气孔率达到1.7%;JZ-88料的体积密度为3.37g·cm-3,显气孔率1.8%;两者的线收缩率随烧结温度的升高呈指数形式增大。JZ-85料和JZ-88料气孔相对较少,多为孤立的闭气孔,致密度明显优于SK-85料和SK-88料。而SK-85中高岭石多以聚集态出现,水铝石常以粒状存在,分布在高岭石的周围,使得烧结后SK-85料莫来石化不能充分进行,刚玉相和莫来石相分布不均匀,采用湿法均化工艺可以降低致密刚玉-莫来石原料的烧结温度。均质莫来石和均质刚玉-莫来石原料在530℃左右出现一个明显的吸热峰,在1000℃左右出现一个尖锐的放热峰。严格控制这两个温度点附近的升温速率,可以避免在隧道窑高温烧成过程中出现塌窑的现象。矾土基均质料的烧结机理符合液相烧结的三个过程:颗粒重排、溶解-沉淀及气孔的产生和融合。随着烧结温度的升高,莫来石晶粒由粒状转变为晶须状,进而转变为柱状,莫来石相晶粒之间相互交叉,形成连续的网络结构,此时保温时间过长,莫来石有熔融现象,彼此交联在一起,存在过烧的现象。升高烧结温度,液相中A12O3和TiO2含量降低,Si02、Fe2O3、K2O、CaO的含量升高,液相粘度降低,有利于烧结的进行;莫来石相中A1203含量升高、Si02含量降低,有利于莫来石化充分进行,并且刚玉相有向莫来石相中溶解的趋势。高温烧结时,K2O、CaO几乎都溶解到液相中,Fe203大部分溶液到液相中,而Ti02则更多的溶解到莫来石相中。矾土基均质料的烧结特征为:低温阶段主要为矾土结构水的脱除过程,氧化铝含量升高,脱水反应的活化能升高,脱水反应进行难度增大。高温阶段主要为矾土的烧结过程,氧化铝含量升高,高温烧结过程中的液相量升高,烧结较易进行。其中均质刚玉-莫来石JZ-85料和JZ-88料高温阶段的液相量较高,属于液相烧结,烧结活化能分别为369.2KJ/mol和289.1KJ/mol。均质莫来石JZ-70料和均质刚玉-莫来石JZ-88料的应用研究表明:均质莫来石JZ-70料可以用来制备低蠕变高铝砖,均质刚玉-莫来石JZ-88料可以作为一种高档耐火原料用来生产高档耐火制品。
[Abstract]:China's high bauxite resources are becoming more and more scarce, especially high-grade bauxite, and there are a large number of small and medium-grade ores that are idle or wasted, the quality stability of the high-alumina-alumina clinker after firing is poor, the firing process is backward, and the environment is serious and the like. In the face of these problems, how to use the low-grade ore to prepare the alumina clinker with high density and high quality is the hot spot of the research. The method for preparing the bauxite-based homogeneous materials with different grades is prepared by adopting a novel wet-process homogenization process of the "the components are designed to be accurate, wet fine grinding, wet forming, high-temperature sintering,", which not only can fully utilize the slag, the leftover materials, the crushed ores, the fine ores and the low-grade bauxite which are produced in the mining process of the alumina ore, And can also solve the problems of environmental pollution and resource waste caused by the bauxite ore in the mining process, thereby realizing the sustainable development of the bauxite resource. The method comprises the following steps of: adopting a wet-process homogenization process to convert the alumina content to be about 63 weight percent,67 weight percent,73 weight percent and 75 weight percent of the green body, and the high-temperature high-temperature sintering is 70 weight percent,75 weight percent,85 weight percent and 88 weight percent of the alumina base homogeneous material, in which the alumina content is 70% by weight and 75% by weight of the alumina-based homogeneous material (referred to as JZ-70 and JZ-75 respectively) are collectively referred to as homogeneous mullite raw materials, The alumina content is 85% by weight and 88% by weight of the alumina-based homogeneous material (referred to as JZ-85 and JZ-88 respectively) as the homogeneous corundum-mullite raw material. The rate of change, weight loss rate, bulk density and apparent porosity of the homogeneous mullite raw material and the homogeneous corundum-mullite raw material under different sintering conditions were tested, and the firing process of the grade-grade alumina-grade homogeneous material was determined. The sintering mechanism of the homogeneous mullite raw material and the homogeneous corundum-mullite raw material is studied, the kinetics of the sintering process is analyzed, and the application of the homogeneous mullite raw material and the homogeneous corundum-mullite raw material is obtained. The results are as follows: The optimal firing system of the homogeneous mullite JZ-70 and the JZ-75 material is at 1600 鈩，
本文编号：2504436
[Abstract]:China's high bauxite resources are becoming more and more scarce, especially high-grade bauxite, and there are a large number of small and medium-grade ores that are idle or wasted, the quality stability of the high-alumina-alumina clinker after firing is poor, the firing process is backward, and the environment is serious and the like. In the face of these problems, how to use the low-grade ore to prepare the alumina clinker with high density and high quality is the hot spot of the research. The method for preparing the bauxite-based homogeneous materials with different grades is prepared by adopting a novel wet-process homogenization process of the "the components are designed to be accurate, wet fine grinding, wet forming, high-temperature sintering,", which not only can fully utilize the slag, the leftover materials, the crushed ores, the fine ores and the low-grade bauxite which are produced in the mining process of the alumina ore, And can also solve the problems of environmental pollution and resource waste caused by the bauxite ore in the mining process, thereby realizing the sustainable development of the bauxite resource. The method comprises the following steps of: adopting a wet-process homogenization process to convert the alumina content to be about 63 weight percent,67 weight percent,73 weight percent and 75 weight percent of the green body, and the high-temperature high-temperature sintering is 70 weight percent,75 weight percent,85 weight percent and 88 weight percent of the alumina base homogeneous material, in which the alumina content is 70% by weight and 75% by weight of the alumina-based homogeneous material (referred to as JZ-70 and JZ-75 respectively) are collectively referred to as homogeneous mullite raw materials, The alumina content is 85% by weight and 88% by weight of the alumina-based homogeneous material (referred to as JZ-85 and JZ-88 respectively) as the homogeneous corundum-mullite raw material. The rate of change, weight loss rate, bulk density and apparent porosity of the homogeneous mullite raw material and the homogeneous corundum-mullite raw material under different sintering conditions were tested, and the firing process of the grade-grade alumina-grade homogeneous material was determined. The sintering mechanism of the homogeneous mullite raw material and the homogeneous corundum-mullite raw material is studied, the kinetics of the sintering process is analyzed, and the application of the homogeneous mullite raw material and the homogeneous corundum-mullite raw material is obtained. The results are as follows: The optimal firing system of the homogeneous mullite JZ-70 and the JZ-75 material is at 1600 鈩，
本文编号：2504436
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