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101.
Determination of Kinetic Equations of Alkaline Activation of Blast Furnace Slag by Means of Calorimetric Data 总被引:2,自引:0,他引:2
A. Fernandez-Jimenez F. Puertas A. Arteaga 《Journal of Thermal Analysis and Calorimetry》1998,52(3):945-955
The alkaline activation of blast furnace slag promotes the formation of new cement materials. These materials have many advantages
over ordinary Portland cement, including high strength, low production cost and good durability. However, many aspects of
the chemistry of alkaline activated slags are not yet very well understood. Some authors consider that these processes occur
through a heterogeneous reaction, and that they can be governed by three mechanisms: a) nucleation and growth of the hydrated
phase; b) phase boundary interactions and c) any diffusion process though the layer of hydration products.
The aim of this paper was to determine the mechanism explaining the early reaction of alkaline activation of a blast furnace
slag through the use of calorimetric data.
A granulated blast furnace slag from Avilés (Spain) with a specific surface of 4450 cm2> g-1 was used. The alkaline activators used were NaOH, Na2CO3 and a mix of waterglass (Na2SiO3·nH2O and NaOH. The solution concentrations were constant (4% Na2O with respect to the slag mass). The solutions were basic (pH 11-13). The mixes had a constant solution/slag ratio of 0.4.
The thermal evolution of the mixes was monitored by conduction calorimetry. The test time was variable, until a rate of heat
evolution equal to or less than 0.3 kJ kg-1 h-1 was attained. The working temperature was 25°C.
The degree of hydration (α) was determined by means of the heat of hydration after the induction period. The law governing
the course of the reaction changes at a certain degree of hydration. From a generally accepted equation, the values of α at
which the changes are produced were determined. These values of α depend on the nature of the alkaline activator. Nevertheless,
for high values of α, the alkaline activation of slag occurs by a diffusion process.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
102.
从非经验参数角度构建基于两原子模型的FexO-SiO2-CaO-MgO-"NiO"渣的势函数,利用分子动力学模拟揭示调控镍渣组分与结构及物理化学性能之间的关系。结果表明: BMH(Born-Mayer-Huggins)势函数能够较好表征FexO-SiO2-CaO-MgO-"NiO"系镍渣的势能。当镍渣中CaO含量为15 wt.%时,Si4+-Si4+间配位数最小,此时熔渣的聚合度最低,有利于扩散。当Fe元素由Fe2+转换为Fe3+后,和O2-结合能力更强,会导致熔渣更难以扩散,因而镍渣的黏度迅速升高,造成冶炼条件恶化,因此在镍闪速熔炼时要严格控制Fe2+/Fe3+的比例。模拟计算的黏度与实测值吻合较好,表明构建的势函数能够较好地反映镍渣的物化性能。 相似文献
103.
104.
本文报道钒渣中测定二氧化钛的硫酸高铈容量法,在盐酸-硫酸混酸介质中,控制磷酸浓度大于3.5mol/L,在用铝片还原Ti(Ⅳ)时可以消除大量钒的干扰,方法用于实际试样分析,结果较好。 相似文献
105.
以钢渣微粉作为研究对象,采用磷酸溶液改性钢渣微粉制备弱酸改性钢渣微粉,利用X射线衍射仪、比表面积及孔径测定仪和环境扫描电镜对弱酸改性钢渣微粉进行表征,研究弱酸改性钢渣微粉的组成成分、孔结构、微观结构和元素组成。结果表明,适量磷酸溶液可以有效去除钢渣微粉中f-CaO,提高弱酸改性钢渣微粉的孔结构。过量磷酸溶液与钢渣微粉中Ca(OH)2发生反应,导致弱酸改性钢渣微粉结构坍塌,整体呈现蓬松状。80 g钢渣微粉,1.6~3.2 mL磷酸溶液时,弱酸改性钢渣微粉具有较低的f-CaO含量与良好的孔结构。为进一步拓展钢渣的利用途径提供一定的技术支持和理论基础。 相似文献
106.
Jie Peng Changsheng Yue Guibo Qiu Min Guo 《Journal of Dispersion Science and Technology》2016,37(8):1097-1103
Slag fiber with desirable properties is a promising candidate for applications as fillers or reinforced materials. Its poor dispersion in bulk materials, however, becomes the major challenge. Some aspects of its physicochemical properties were focused upon in the present article. The effect of three kinds of dispersants, viz., sodium carboxymethyl cellulose (CMC), anionic polyacrylamide (APAM), and cationic polyacrylamide (CPAM), as well as their combinations on the dispersion of slag fiber in aqueous solution was investigated. The viscosities of fiber suspensions were measured and the results were correlated with the dispersion of suspensions. It was shown that the slag fiber appeared amorphous, smooth surface with high length/diameter (L/d) ratio and negatively charged in water. The dispersion of slag fiber in aqueous solution directly depended on the dispersants. The optimal uniform and stable fiber suspension could be achieved under the dispersant concentration of the combination of 2 wt% CMC and 0.25 wt% APAM. In this case, the fiber concentration was as large as 25 g/L. In addition, the plausible dispersion mechanism of slag fiber in aqueous solutions was elucidated based on the electrostatic steric stabilization. 相似文献
107.
Dweck J. Ferreira da Silva P. F. Silva Aderne R. Büchler P. M. Cartledge F. K. 《Journal of Thermal Analysis and Calorimetry》2003,71(3):821-827
This paper presents a method to study cement hydration at ambient temperatures by using a micro processed non-conventional
differential thermal analysis (DTA) system, which was used to evaluate the solidification/stabilization process of tannery
wastes produced in the leather industry. The DTA curves of pastes composed by slag cement, Wyoming bentonite and waste are
obtained in real time and used to analyze the heat effects of the reactions during the first 24 h of hydration. By applying
a deconvolution method to separate the overlapped DTA peaks, the energy released in the several hydration stages may be estimated
and consequently, the effects of each component on the solidification process. The highest separated DTA peak occurs during
the several early stages of cement hydration and is due mainly to tricalcium silicate hydration. Very good correlation shows
that the greater is the waste content in the paste composition, the higher is its effect on the rates of reactions occurring
during the induction (dormant) period of cement hydration. The presence of bentonite used as a solidification additive in
the stabilization process has a similar but less dramatic effect on the dormant period.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
108.
Acosta A. Iglesias I. Aineto M. Romero M. Rincón J. Ma. 《Journal of Thermal Analysis and Calorimetry》2002,67(1):249-255
IGCC slag is a vitreous residual product from the new induction gasification combined cycle gasification thermal power plants. In order to characterize this waste as secondary new material for the production of new glasses and glass-ceramics as construction materials; this slag from the Puertollano, Ciudad Real, Spain power plants has been fully thermally investigated. After controlled heating this waste gives rise to hematite, anorthite, and cristobalite crystallized materials.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
109.
By adding small amount of TiO2, aluminum slag could be used to synthesize cor-dierite, α-Al2O3, TiO2 and dehydrated talc could generate solid solution to accelerate the solid-state reaction to form cordierite. The experimental results show that the content of cordierite increases with the increase of TiO2 added. 3.0% of TiO2 is determined to be the best amount, because all crystalline substances are converted into cordierite at this content. Philips X‘pert plus software analysis shows that when the content of TiO2 is from 0 to 1.0%, cordierite has the same hexagonal structure as the single crystal and the lattice parameters change slightly; when the content of TiO2 is from 1.0 to 2.0%, the cordierite still keeps hexagonal structure but the lattice parameters change greatly; when the content of TiO2 is from 2.0 to 3.5%, the cordierite is converted from hexagonal into rhombic and the lattice parameters change accordingly. 相似文献
110.
研究了碱酸比不同的3种熔融煤灰(A、J1和J2)在莫来石和刚玉两种耐火材料上的界面特性。结果表明,A对莫来石和刚玉都有很好的润湿性,而J1和J2对这两种耐火材料则经历由不完全润湿到润湿的过程。熔渣与耐火材料(S-R)界面宽度随着接触角减小而增大。从灰渣开始熔融至1 520 ℃,熔融煤灰J1在耐火材料表面上的接触角随着倾角的增加而减小;当倾角为20°时,其接触角突然增大。SEM-EDS分析表明,由于界面反应,A比J1更容易渗透进入耐火材料内部。对于碱酸比不同的煤灰,渗透和酸碱反应是熔渣对耐火材料腐蚀的关键。 相似文献