Effect of Sound Waves on Decarburization Rate of Fe-C Melt
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DEVELOPMENT and commercialization of hot metal pretreatment have had a profound effect on the converter process. The main purpose of the converter process in its modern form is to remove carbon from hot metal and to achieve the required temperature of steel that is necessary to perform the following ladle treatment and casting. In the process, oxygen is blown onto the surface of hot metal at supersonic speed through a top lance. This causes formation of an impingement cavity on the melt surface, where oxidation of carbon and iron is initiated. Besides, weakly oxidizing or inert gas is blown into the molten bath through the bottom tuyeres to additionally agitate the melt. The decarburization reaction produces CO being readily oxidized by O2 to CO2, which can react again with iron and dissolved carbon. The iron oxide, mainly FeO, is also involved in the decarburization, yielding CO and CO2. SERGEY V. KOMAROV is with the Graduate School of Environmental Studies, Tohoku University, 6-6-02 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan. Contact email: komarov@ material.tohoku.ac.jp MASAMICHI SANO is with the Department of Materials Processing Engineering, School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan. Manuscript submitted April 7 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS B
Besides, FeO reacts with lime and other slag-forming fluxes to form slag. Although the modern converter operates at less slag to metal ratios, the slag is essential to protect the converter lining against the erosive action of FeO and to absorb impurities coming from scrap. The impinging oxygen jet causes the splashing of hot metal droplets followed by their oxidation. These droplets are transferred into the metal and slag, where they are involved in the oxidation-reduction reactions. More details on the phenomena taking place at the impingement cavity can be found in the relevant literature.[1,2] The tremendous amount of gas released in decarburization causes vigorous generation of the so-called bubble-burst dust carried out from the converter by the exhaust gas. Yet another kind of dust termed ‘‘fume’’ is generated at the impingement zone as a result of overheating of its surface.[3] Especially severe dust formation occurs at the beginning of blowing operation when the melt surface is still uncovered with slag. Besides, the gas evolution causes formation of slag-metal emulsion, the phenomenon termed ‘‘slag foaming.’’ Generally, slag foaming is a positive phenomenon for the converter process because it contributes to the protection of converter lining, absorption of dust, and prevention of spitting.[2] However, when the slag foaming occurs under uncontrolled conditions, it can cause serious problems in the converter operation.
Thus, the reactions of decarburization and iron oxidation are the major reactions in the converter process. Hence, proper control of the reaction kinetics is of great importance in determining the efficiency of the converter process, both technically and environmentally. The aforem
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