Development of New Iron and Steel Refining Process with In-Situ Produced Alkaline Earth Metal Vapor

近年来，对高质量钢材的需求越来越大，这就要求钢铁行业生产出高纯净度的钢材。众所周知，镁对硫和氧有很强的亲和力。因此，镁可以作为强脱硫剂和脱氧剂，降低超低的硫和氧浓度，镁在加入熔体时的汽化损失大，精炼成本很高。因此，镁还没有在实际的精炼操作中得到应用。本研究的目的是实现镁精炼的高效、低成本，以及向熔体中添加镁的安全操作。利用氧化镁碳热还原和铝热还原原位生成的镁蒸气对铁水进行脱硫脱氧处理。从过程工程的角度对实验结果进行了讨论。在实验中，由氧化镁和铝组成的球团矿po…更多的人被装进氧化铝、氧化镁或石墨管中。管子浸入了铁水中。通过熔体的热传递加热球团产生镁蒸气，镁蒸气与载气一起通过管子下部的孔注入熔体。实验条件变化很大，如铁水和球团的质量、载气流量、初始硫和氧浓度、温度、球团的组成、氧化镁的粒度、球团的装料比例等。由于氧化镁碳热还原生产镁的速度慢，铁水的脱硫和脱氧进展缓慢，精炼速度受镁的供应控制。相反，氧化镁的铝热还原速度很快，脱硫率和脱氧率很大。但是，实验初期镁的分压过高，导致脱硫率和氧化率很低。结果表明，通过优化控制喷吹气泡内的镁分压，可以显著提高镁的精炼效率，降低精炼成本和排渣量。较少

Recently, demands for high quality steel are becoming more and more severe, so that the steel industry is requested to sepply highly pure and clean steel. As is well known, magnesium has strong affinity to sulfur and oxygen. Hence, magnesium can be a strong desulfurization and deoxidation reagent, and reduce the sulfur and oxygen concentration ultra low, the vaporization loss of magnesium at the addition to the melt is large, and the refining cost is very high. Consequently, magnesium has not been used in the practical refining operation.The purpose of the present study is to achieve the efficient and low cost refining with magnesium, and safe operation of magnesium addition to the melt. Magnesium vapor produced in-situ by carbothermic and aluminothermic reduction of magnesia was used to desulfiirize and deoxidize molten iron. The experimental result was discussed from the view point of process engineering. In the experiments, the pellets, which was composed of magnesia and aluminum po … More wders, were charged into an alumina, magnesia or graphite tube. The tube was immersed into the iron melt. The pellets were heated by heat transfer from the melt to produce magnesium vapor, which was injected into the melt together with carrier gas through holes drilled at the lower part of the tube. The injected magnesium reacted with sulfur and oxygen in the melt.The experimental conditions were varied widely, such as masses of molten iron and pellets, carrier gas flow rate, initial sulfur and oxygen concentrations, temperature, composition of pellets, powder size of magnesia, and dividing pellet charging into several portions. Since the production rate of magnesium by the carbothermic reduction of magnesia was slow, the desulfurization and the deoxidation of molten iron proceeded slowly, and the refining rates were controlled by the supply of magnesium. On the contrary, the aluminothermic reduction of magnesia was very fast, and the rates of desulfurization and deoxidation was very large. But, the partial pressure of magnesium at the initial stage of the experiment was so high that the desulfurization and the oxidation efficiencies were very low. It is demonstrated that the optimal control of the magnesium partial pressure in the injected bubble can improve the refining efficiency of magnesium drastically, and the refining cost and the amount of slag discharge can be reduced sharply. Less