Combined blowing process in converter steel making Apr30

Combined blowing process in converter steel making...

  Combined blowing process in converter steel making Inhomogeneities in chemical composition and temperature are created in the melt during the oxygen blow in the top blown converters due to the lack of the mixing in the metal bath. There is a relatively dead zone directly under the jet cavity in the converter. The necessity to improve the steel making process in the top blown converter has led to the development of the combined blowing process. The first combined blowing practice to be commercially accepted was the LBE (Lance Bubbling Equilibrium) process developed by ARBE-IRSID. This process is much more closely related to the BOF process in that all the oxygen is supplied from the top lance. The combined blowing aspect is achieved by a set of porous elements installed in the bottom of the converter through which argon or nitrogen is blown. In LBE process the nitrogen gas is typically used almost exclusively for the majority of the blow in the range of 3 -11 N Cum/min. However in the later part of the blow when nitrogen absorption can create a problem, argon gas is used for stirring. In addition, argon is used almost exclusively as the inert gas for post blow stirring, at this time the rate is increased to 10-17 N Cum/min. The process is shown in Fig.1. Fig 1 Combined blowing processes The profile of a porous element is shown in Fig 2   Fig 2 Profile of a porous element for the LBE process The bottom buildup and the subsequent loss of the porous element is the major problem associated with this process. The difficulties in maintaining the LBE elements operational have led to pursue the application of the non cooled tuyeres. Here also the oxygen is delivered through...