钢渣对镁碳砖侵蚀机理研究

发布时间：2018-05-11 16:28

本文选题：镁碳砖 + 钢渣　；参考：《安徽工业大学》2015年硕士论文

【摘要】：在钢铁行业处于困难的现阶段,节能降本成为钢铁企业生存的关键,所以延长炼钢炉衬寿命十分重要。镁碳砖因为其优质性能,被广泛的应用在钢铁行业中。随着钢铁行业的发展,钢渣的组分更加复杂化,因此对镁碳砖的抗渣性能提出更高的要求。为提高镁碳砖衬的使用寿命,就必须深入探究镁碳砖的侵蚀过程及机理。本文在总结国内外炼钢用镁碳砖炉衬损毁基础上,结合某耐火材料厂以及炼钢电炉和精炼钢包冶炼条件,对电炉炉衬和钢包内衬使用后的残样分析、静态渣蚀实验研究,着重探讨炉渣的碱度、氧化性以及氟化钙含量的对镁碳砖侵蚀机理的影响。得到的主要结论如下。(1)使用前后镁碳砖的物理、化学性质有很大的改变,第一:由于高温条件下石墨氧化作用,首先导致砖体内的抗氧化剂被消耗,其次使砖体内部的石墨网状结构被氧化破坏,再加热应力的作用,使砖体强度降低;第二,整个砖体的颜色和镁砂的粗糙程度以及颜色都发生了变化,这与碳对镁砂的还原有关以及镁砂晶界内成分变化有关。(2)由现场取样分析以及热侵蚀实验结果得出电炉中钢渣对镁碳砖的侵蚀机理:电炉中镁碳砖的侵蚀机制中主要有两个方面的因素在起重要的作用。一是由于渣中含有大量的氧化铁,氧化铁将石墨氧化,自身被还原成金属铁,并且破坏了石墨网状结构的连续性,致使镁砂容易剥落。二是,当石墨被氧化后大量的镁砂颗粒暴露出来与渣接触,由于铁对镁砂的渗透性,致使镁砂以两种方式溶解在渣中,其一是从镁砂晶界中侵蚀、另一种是直接溶解镁砂,两者相互结合,把镁砂分割开来,逐渐溶解在钢渣中。(3)由现场取样分析以及热侵蚀实验结果得出钢包中钢渣对镁碳砖的侵蚀机理:钢包中镁碳砖的侵蚀机制包括两点:第一点是低碱度条件下镁砂的溶解,由于钢包精炼渣中铁的氧化物含量特别少,因此镁砂的溶解主要靠氧化镁与氧化钙、二氧化硅形成低熔点氧化物,进而导致镁砂的溶解,并且二元碱度为1.0时,侵蚀速率最快,碱度为0.8和1.2时侵蚀速率有所降低;第二点是氟化钙的加入将大大改善镁砂溶解的热力学和动力学条件,炉渣中氟化钙含量越高,炉渣对镁碳砖的侵蚀能力越强,侵蚀速率越快。
[Abstract]:In the difficult stage of iron and steel industry, energy saving and reducing cost is the key to the survival of steel enterprises, so it is very important to prolong the lining life of steelmaking furnace. Magnesia-carbon brick is widely used in steel industry because of its high-quality properties. With the development of iron and steel industry, the composition of steel slag becomes more complicated. In order to improve the service life of magnesia-carbon brick lining, the erosion process and mechanism of magnesia-carbon brick must be deeply studied. On the basis of summing up the damage of magnesia carbon brick lining used in steelmaking at home and abroad, combined with the smelting conditions of a refractories factory and steelmaking electric furnace and refining ladle, the residual samples of furnace lining and ladle lining are analyzed, and the static slag corrosion experiment is studied in this paper. The effects of basicity, oxidation and content of calcium fluoride on the erosion mechanism of magnesia-carbon brick were discussed. The main conclusions are as follows: (1) the physical and chemical properties of magnesia and carbon bricks have great changes before and after use. First, the oxidation of graphite at high temperature results in the depletion of antioxidants in the bricks. Secondly, the graphite mesh structure inside the brick body is destroyed by oxidation, and the strength of the brick body is reduced by reheating stress. Second, the color of the whole brick body and the roughness and color of magnesia sand have changed. This is related to the reduction of carbon to magnesia and the change of composition within the grain boundary of magnesia. (2) based on the field sampling analysis and thermal erosion experiment results, the erosion mechanism of slag to magnesia carbon brick in electric furnace is obtained: in the corrosion mechanism of magnesia carbon brick in electric furnace There are two main factors that play an important role. One is that the slag contains a lot of ferric oxide which oxidizes the graphite and reduces itself to metal iron which destroys the continuity of the graphite network and makes the magnesite flake off easily. Second, when a large number of magnesia particles are exposed to slag after the graphite has been oxidized, because of the permeability of iron to magnesia, magnesia is dissolved in slag in two ways, one is erosion from the grain boundary of magnesia, the other is direct dissolution of magnesia. The two are combined to separate magnesia. The corrosion mechanism of slag on magnesia and carbon brick in ladle is obtained by field sampling analysis and thermal erosion experiment. The corrosion mechanism of magnesia carbon brick in ladle includes two points: the first one is the dissolution of magnesia sand under low alkalinity. Because the content of iron oxides in ladle refining slag is very small, the dissolution of magnesia mainly depends on magnesium oxide and calcium oxide, and silica forms low melting point oxide, which leads to the dissolution of magnesia sand, and when the binary basicity is 1.0, the erosion rate is the fastest. The second point is that the addition of calcium fluoride will greatly improve the thermodynamic and kinetic conditions of magnesite dissolution. The higher the content of calcium fluoride in slag, the stronger the erosion ability of slag to magnesia and carbon brick. The faster the erosion rate is.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TF748.05;TQ175.1

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