Physical, chemical and thermal histories of an oxygen bubble in bath during bottom blown process

Abstract

A mathematic model has been developed for an oxygen bubble rising in metal during a bottom blown process. The model successfully coupled local reactions and mass transport with heat transport between metal and the bubble surface, and between the latter and the bubble interior. This novel method reveals the physical, chemical and thermal histories of an oxygen bubble during a bottom blown process. An oxygen bubble rising in Fe-3%C metal under conditions of the oxygen bottom blown process was described by the modelling. The results show (1) the heat supplied to the bath is sourced from the secondary combustion in the bubbles rather than from the decarburisation at a bubble surface; (2) the temperature of a bubble surface reached a maximum of few degrees higher than the bath at few centimetres above the nozzle; (3) the maximum heat supplied to the bath by a bubble midway along the bubble trajectory is much more than the total heat supplied by the bubble reaching the bath surface; (4) the energy in the process-off gas is as high as three-fold of that received by the bath; and (5) iron is unlikely to be oxidised in front of the nozzle.

Study on metallurgical characteristics of the bottom-blown O2–CaO converter

“…The oxygen blown at the bottom of the molten pool can provide stronger agitation, and the lime powder, which is blown in with oxygen, has a large specific surface area, providing a larger slag-metal reaction area that makes slag smelting easier, such as OBM/Q-BOP converter [11,12]. K-BOP converter blows 30% of the total oxygen required for steel making from the bottom of the furnace and simultaneously blows lime powder, which greatly improves the effect of dephosphorization and desulphurization, makes the blowing process more stable and controllable, and improves the quality of steel while reducing the consumption of raw and auxiliary materials [13][14][15][16][17].…”