| Budget Amount *help |
¥12,300,000 (Direct Cost: ¥12,300,000)
Fiscal Year 2001: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 1999: ¥4,800,000 (Direct Cost: ¥4,800,000)
|
|---|
| Research Abstract |
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
|
