【作者】 秦守婉；

【导师】 陈益民；

【作者基本信息】 中国建筑材料科学研究总院 ， 材料学， 2007， 博士

【摘要】 阿利特是水泥熟料中最主要的强度提供者,其含量和活性的提高必将赋予熟料高的胶凝性。然而,由于阿利特是水泥熟料矿物中生成温度最高的矿物,提高水泥熟料中阿利特含量会给生产带来一定的困难。本文从高阿利特熟料的基本矿物形成过程入手,分析生料性质和工艺参数对高阿利特熟料矿物形成动力学的影响;研究高阿利特熟料中阿利特的形成动力学过程以及杂质离子在阿利特中的固溶情况及对阿利特多晶转变的影响;在实验室和工厂进行了高阿利特含量熟料的烧成,并对其物理性能进行了分析测试。研究结果表明,在熟料率值相同的情况下,合理控制生料细度,使物料的颗粒尺寸较小,溶解和扩散都易于进行,因而降低了C3S形成的表观活化能。某些废渣及杂质离子的引入可以降低体系液相出现温度,改善液相性质,从而改善了C3S生成环境,降低C3S形成的表观活化能;因此,在生产过程中可以通过调整生料的化学组成或者物理特性达到改善易烧性的目的。研究同时表明,可以根据原料情况,选择适宜的配料方案和生料细度控制范围,还应根据生料的特性合理选择熟料的煅烧温度,都是实际生产中改善生料易烧性的可行方法。研究表明,采用分步煅烧可以在很大程度上改善易烧性,降低熟料的烧成温度。当采用1350℃下煅烧所得的前驱体(主要矿物组成为贝利特、铁相和铝相)进行高阿利特熟料的配制时(TC系列),在1300℃下阿利特已经大量形成,所形成的阿利特晶核数量较多,其成核速率较大。随着温度的升高,阿利特晶体的平均尺寸增大,在1300~1400℃之间,晶体的长大较快,主要以生成M1型的非稳态长大为主;随着温度继续升高(高于1400℃),长大速率变慢,开始大量出现稳态长大,生成具有环带结构的M3型阿利特,特别是原属Blite矿巢存在的区域。通过对研究结果进行分析,基本可以肯定在煅烧过程中液相对于C3S的形成的贡献在一定程度上大于C2S的“晶核”作用,二者的联合作用最佳。熟料体系中杂质离子的浓度在一定程度上决定着阿利特中杂质离子的固溶量,而固溶又影响着阿利特的晶型变化。在其他因素相同的情况下,随着硅率n的增大,Al、Fe、Mg、P在阿利特中的固溶量相对变化不大,阿利特的晶型没有明显变化。Fe的固溶量随铝率p的增大而下降,Al的固溶量随铝率p的增大而增加。当熟料中有Mg存在时,熟料所经的热历史及Mg在阿利特中的固溶情况,对其晶型的影响较大。研究表明煅烧制度对阿利特中杂质元素固溶量有直接影响,从而影响阿利特的晶型。对于不同的煅烧制度下所得熟料,Al、Fe、Mg、P等在阿利特中的固溶量有所不同。随淬冷开始温度的降低,Al、Fe、Mg、P等在阿利特中的固溶量减少,其中Al的固溶量降低明显,Fe、P的固溶量稍降低。不同煅烧温度下所得熟料内阿利特中的杂质离子的固溶量也不同。随着温度的升高,阿利特中Fe的固溶量降低。在较低温度下(1350℃)烧成的熟料中的阿利特的衍射图谱接近的R型的衍射特征。随着煅烧温度的增加及固溶物含量的变化,阿利特的晶型发生变化。煅烧气氛对Al固溶量的影响较大,氧化气氛条件下所获得熟料中的阿利特中Al的固溶量稍高;还原气氛下烧成的阿利特中Fe的固溶量较高;在还原气氛下烧成的阿利特中Mg的固溶量稍降低;烧成气氛对P的固溶量影响不明显。虽然还原气氛下Al的固溶量下降,Fe的固溶量升高,但由于本实验条件下变化范围不大,不同煅烧气氛下熟料中的阿利特的晶型变化并不明显。实验室高阿利特水泥熟料的烧成研究表明,适当的氟磷掺杂有利于高阿利特含量熟料的烧成,并且可以进一步提高熟料的强度。采用钢渣和磷渣进行配料,煅烧所得熟料呈现良好的岩相结构且具有较高的强度。工业生产高阿利特含量水泥熟料过程中,不能仅以f-CaO为主要日常检测指标,还要加强熟料岩相结构的检测及控制。两次试生产基本达到了973课题要求的“两个70”(C3S含量70.0w%和28d抗压强度70.0MPa)。在配料合理、生料稳定、窑内热工制度适宜的情况下,可以顺利实现高阿利特水泥熟料的工业生产,获得性能优异的熟料。更多还原

【Abstract】 The performance of clinker could be improved remarkably by increasing the content of Alite in clinker. However, the formation of Alite is most difficult in all the clinker minerals, some problem will be caused with the increase of Alite. In this thesis, some researches were carried out about the kinetics of the forming process of minerals and the kinetics of crystallizing process of Alite in high Alite content cement clinkers. The concentration of ions in Alite and the morphology of Alite under different physical and chemical conditions were also studied in this dissertation. Clinkers with high content of Alite were manufactured in our lab and in two plants, and the physical properties of them were tested.The results showed that the burnability of clinker can be improved by reasonable parameters (such as fineness), doping foreign ions and appropriate raw meal properties. With a reasonable fineness, the smaller particle size is in favor of solution and diffusion, thus the apparent activation energy of Alite formation can be decreased. The temperature of liquid phase formation was reduced and the properties of liquid phase were improved by adding some ions and industrial slag into the raw meals. High quality clinkers can be produced by adjusting the chemical composition of raw meal, adopting a reasonable parameters and appropriate burning temperature during the manufacturing process in plants.The burnability of clinkers was improved remarkably by adopting a two-steps burning method, and the sintering temperature was decreased by more than 100℃with pioneers (main components are Belite, C3A and C4AF) burned at 1350℃(TC group). As for TC group, since most Alite formed at 1300℃, it could be concluded that the nucleation of Alite was prevalent. With the increase of temperature, Alite crystals grew quickly in the range of 1300℃to 1400℃and preferred to M1 form. But the rate of growth became slower with the decrease of supersaturation while the temperature exceeded 1400℃. And Alite preferred to M3 form with silicate zonation, especially at the border of a pioneer particle. According to the results, it can be basically made sure that the effect of liquid phase is stronger than the effect of“crystal seed”of C2S, and the corporate effect of them is better.The solid solubility of ions in Alite depends on the concentrations of ions in clinkers at a large extent. The mass fraction of Al、Fe、Mg、P fluctuated in a narrow range and the polymorphic form showed no obvious change according to the XRD patterns with the increase of silica modulus (SM). The solid solubility of Al increased and Fe decreased with the increase of alumina modulus (IM). The XRD patterns of Alite showed remarkable different while MgO existed in clinkers.As for the clinkers burned at different temperatures or different cooling conditions, the solid solubility of ions in Alite was different. The mass fractions of ions decreased while the quenching temperature decreased. With the increase of temperature, the solid solubility of Fe decreased. The XRD patterns of Alite extracted from clinkers burned at lower temperatures(1350℃) is similar to the typical patterns of R form Alite. The solid solubility of Al was higher in Alite burned at an oxidation environment while the solid solubility of Fe was higher in Alite burned at a reducing environment.The results of experiments on manufacture of clinker with high Alite content showed that the burnablity and the strengths of clinker were improved with F/P doped in the raw meals. Clinkers with an expectant photographic structure and higher strengths could be produced while steel making slag (SMS) or phosphorus making slag (PMS) was introduced into raw meals.We should pay more attention to the microstructure of clinker not just concentrate on the content of free lime (f-CaO) during the manufacturing process in a plant. The results of the twice industrial experiments basically met the goals of“two 70%”(the C3S content is about 70.0w% and the 28d’strength is about 70.0MPa). In a word, clinkers with high performance can be produced in a plant with a reasonable chemical composition, parameters of raw meal and an appropriate heating condition.更多还原