An Attempt to Correlate Electrochemical Desulfurization of Molten Iron Using CaO–Al2O3–MgOsat. Molten Slag and Applied Electricity at 1673 K (1400 °C)

Autor: Donghyun Kim, Youn-Bae Kang
Rok vydání: 2021
Předmět:
Zdroj: Metallurgical and Materials Transactions B. 52:2960-2970
ISSN: 1543-1916
1073-5615
DOI: 10.1007/s11663-021-02289-1
Popis: Desulfurization of molten iron by molten slag is an electrochemical reaction. Previous investigations confirmed that applying electricity could enhance the desulfurization of molten iron, but a quantitative relation between the electricity and the desulfurization was not fully elucidated. The present study attempted to correlate the extent of the electrochemical desulfurization with the applied electricity via a series of high-temperature desulfurization experiments and thermodynamic analyses. A molten iron containing C and S was allowed to react with CaO– $$\hbox {Al}_{{2}}\hbox {O}_{{3}}$$ – $$\hbox {MgO}_{\text {sat.}}$$ slag at 1673 K (1400 $$^\circ $$ C), with and without the electricity of constant current. S distribution coefficients ( $$L_{\text {S}}$$ = (pct S)/[pct S]) were obtained after the normal and the electrochemical equilibria, respectively. The obtained results were interpreted by employing the Nernst equation in order to extract the potential difference ( $$\varDelta \phi _{\text {S}}$$ ) for the electrochemical desulfurization. It was found that applying electric current (I) increased the $$L_{\text {S}}$$ after the electrochemical desulfurization, which resulted in the increase of $$\varDelta \phi _{\text {S}}$$ . A resistance, $$R_{\text {DeS}} = \varDelta \phi _{\text {S}}$$ /I, or a specific resistivity, $$\rho _{\text {DeS}} = \varDelta \phi _{\text {S}}$$ /(I/A), where A is the cathodic area, for the electrochemical desulfurization was defined, which can be used to characterize the susceptibility to the electrochemical desulfurization. It was found that $$R_{\text {DeS}}$$ was independent of the I within the range of this investigation, decreased as (pct CaO)/(pct $$\hbox {Al}_{{2}}\hbox {O}_{{3}}$$ ) increased and was proportional to the resistance of the slag ( $$R_{\text {slag}}$$ ). A favorable condition for the electrochemical desulfurization is not the same as that for the normal desulfurization condition. The $$\varDelta \phi _{\text {S}}$$ , which is an indicator of the extent of electrochemical desulfurization, was independently predicted by employing a thermodynamic model for the oxysulfide slag. The model prediction was in a good agreement with the experimental data. The model was used to predict necessary current level for a desired electrochemical desulfurization.
Databáze: OpenAIRE
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