Kinetics of the Volatilization Removal of Zinc from Manganese Dust

Abstract

Manganese dust which contains significant amounts of manganese, zinc and potassium is collected from the off-gas during manufacturing ferromanganese and silicomanganese alloys at Dongbu Metal Company in Korea. The removal of zinc and potassium from the manganese dust is very important in the process for recycling the dust back into the ferromanganese smelting furnace. This is because the potential accumulation of zinc and potassium in the smelting furnace can cause irregularities in the operation of the smelting furnace. In this study, the reductionvolatilization reaction of the zinc oxide contained in the manganese dust with carbon was examined at reaction temperatures between 923 and 1323 K in nitrogen atmosphere using a thermogravimetric method. The results of experiments on the kinetics of the reaction are presented in this paper. Experimentally, the rate of this reaction was demonstrated by the removal of 99% zinc in 20 min at 1198 K under a carbon addition amount of 9 mass%. The reduction-volatilization reaction started at above 973 K and proceeded very fast at above 1023 K. Furthermore, manganese and iron oxides in the dust was partially reduced during the reaction. The shrinking-core model for a surface chemical reaction control was found to be useful in describing the reduction-volatilization reaction rate, which had an activation energy of 173 kJ/mol (41.3 kcal/mol). [doi:10.2320/matertrans.M2010108]