논문 : 건식제련 ; 흑연 및 Fe-C 용탕에 의한 크롬광의 용융환원에서의 율속단계 = Research Paper : Pyrometallurgy ; Rate-Controlling Steps in Smelting Reduction of Chrome Ore by Graphite and Fe-C Melt

다국어 초록 (Multilingual Abstract)

The smelting reduction behaviors of chrome ore by Fe-C melt and graphite in the molten slag of CaO-MgO-Al2O3-SiO2, system in which a dissolution as a rate-controlling process was excluded have been studied to determine rate-controlling steps in the temperature range of 1475 to 1650℃. Samples were investigated using ICP-AES and EDS. The results were as follows: In the smelting reduction experiments by Fe-C melt, the apparent activation energy was found to be 104kJ/mol and independent of initial chromium content in the Fe-C melt. Also, mass transfer coefficient was constant regardless of the variation of slag volume. Therefore, it was concluded that the reaction rate was controlled by mass transfer of chromium oxide through the slag boundary layer. In the reduction experiments by graphite, the apparent activation energy was found to be 185kJ/mol. The reaction rate under these conditions was found to be mixed control of chemical reaction involved in breaking the C-C bonds in the carbon lattice and a mass transfer of chromium oxide in the slag phase. Dissolution of chrome ore was interrupted by protection of a crust of high-melting MgAl2O4 euhedral crystals which had precipitated from the molten slag when the content of (MgO+Al2O3) was higher than about 3lwt% at 1500℃, 38wt% at 1550℃, 45wt% at 1600℃ and 5lwt% at 1650℃, respectively.