Article ID
95BEN41006
Title
Elimination of copper from the molten steel by NH3 blowing under
reduced pressure
減圧下アンモニアガス吹き付けによる溶鋼からの脱銅
Author(s)
Katsutoshi Ono
Eiji Ichise
Ryosuke
O.Suzuki
Toshitsugu Hidani
Publication/Publisher
Steel Research, Vol.66, No.9, (1995) pp.
372-376.
Abstract
Based on the finding that blowing of NH3 gas onto molten pure
copper at atmospheric pressure causes its evaporation of enormously high rate,
attempts have been made on elimination of copper dissolved in molten steel by
NH3 gas blowing under reduced pressure. Typical behaviors of molten steel when
attacked by NH3 gas are boiling, splashing and in a violent case slopping from
the crucible. These phenomena are accompanied by an immense increase in the
surface area from which volatile species are able to evaporate and may be useful
for vacuum metallurgical process. In this investigation, the decuprization
experiments have been conducted to measure the rate at which the copper level in
the molten steel is reduced using a vacuum induction furnace and blowing NH3 gas
through a vertical water-cooled copper nozzle. The data were represented in
terms of the amount of copper transferred from the melt to the gaseous phase per
unit surface area and time. According to these experiments, complete
decuprization was attainable confirming selective evaporation of copper from
molten steel under reduced pressure. So far as the mechanism of copper
elimination by NH3 gas, beside the enhanced vacuum evaporation of metal by
cooling effect due to endothermic decomposition of NH3, the formation of
volatile copper compound was suggested from the fact that the copper could be
removed down to extra-low level as several ppm even under residual gas pressure
of order of 10 Torr.