Fundamental Study on Effects of Various Factors on Fluid Behavior during Intermediate Deslagging of MURC (Multi-Refining Converter) Process

Abstract

Synopsis : To achieve high-efficiency intermediate deslagging in MURC (Multi-Refining Converter) process is an important issue. In order to obtain the basic knowledge concerning the fluid behavior during intermediate deslagging, simulation using water model was carried out and the effects of tilting pattern, properties of liquids and the shape of vessel mouth (installation of weir) were evaluated. As the results, the followings were observed.1) The metal starts spilling before reaching the inclined angle that is geometrically calculated from the remaining volume inside the vessel due to the uplift of metal edge. 2) Reduction of deslagging time with the same deslagged amount becomes possible by using the slowdown pattern in tilting rate near the end of deslagging. 3) Metal is easy to spill when slag viscosity is high and the density difference between metal and slag is small. 4) Deslagging is improved by installation of weir to the vessel mouth. Based on the results, a simple model was built by focusing on the balance between shear force and gravitational force (buoyant force) and the metal-spill-point and deslagged amount were estimated. Furthermore, from the detailed analysis using computational fluid dynamics, the above-mentioned phenomena were reproduced.

New trends in basic oxygen furnace dephosphorization

“…With the application of the water model, the authors concluded that a metal's spilling tendency increased as the viscosity of the slag increased and as the density difference between the steel and slag became smaller. It was further outlined that the installation of a weir to the mouth of the vessel was found to be beneficial for eliminating metal spill, which is one of the most important difficulties of slag dumping in the double-slag practice [35]. In another paper about the double-slag process, it indicated that 55% of the Nippon Steel's production was based on the MURC process and that lime usage in BOF was reduced by more than 40% [36].…”

Einstein–Roscoe regression for the slag viscosity prediction problem in steelmaking

“…To this end, in the real operation scene, slag is usually treated simply as pure liquid. However, the real slag is considered to be a multiphase fluid consisting of solid and liquid 1 , 2 . Thereby based on this idea, we attempt to model the slag viscosity as a function of the fraction of solid and liquid phases, shape and size of the solid phase particles.…”

Physical Simulation of Powder Spraying at the Bottom of a Converter

“…[4][5][6][7][8][9][10] Because the converter is more likely to form dephosphorization conditions with strong oxidizing properties, high basicity, and suitable temperature, many dephosphorization processes with the converter as the main body have been formed. For example, the multirefining converter (MURC) process uses a single converter, [11][12][13][14][15] as the simple refining process (SRP), [16][17][18] LD converter-optimized refining process (LD-ORP), [19][20][21][22][23] and Baosteel BOF refining process (BRP) [24][25][26] as duplex processes. Since the powder spraying process can greatly improve the dephosphorization rate, it has been widely used in the existing dephosphorization process.…”