Dephosphorization of ferromanganese using BaCO3-based fluxes by submerged injection of powders: A preliminary kinetic study

Abstract

contact reaction is rather harmful, when the transitory reac-Dephosphorization of tion is also high, because uneconomically excess species Ferromanganese using BaCO 3transport beyond the equilibrium value takes place to the Based Fluxes by Submerged slag phase, which later reverts back to the metal phase. However, an increase in permanent contact reaction, at a Injection of Powders: A Preliminarycomparatively lower rate of transitory reaction, was found Kinetic Study to be beneficial. Based on their laboratory scale experiments on desulfurization of liquid iron at 4-kg scale laboratory setup, they observed that the relative contributions of transi-G.G. ROY, P.N. CHAUDHARY, R.K. MINJ, tory and permanent contact reactions were almost equal. and R.P. GOEL However, for a system with different equilibrium partition Ferromanganese constitutes almost half of the total ferroratios and different gas and powder flow rates, the depths alloys produced in India because of its extensive use in of the injection-relative contribution may be different. the iron and steel industry. Ferromanganese is used as aIn view of the preceding discussion, the present article deoxidizing and alloying agent in steelmaking but is one of seeks to calculate the relative contribution of the permanent the main sources of phosphorus contamination of steel. The and transitory contact reactions for the present dephosphorihigh phosphorus content (0.35 to 0.50 pct) of high carbon zation study, which might subsequently help in selecting the ferromanganese originates from the manganese ores, the design parameters that could be of importance for efficient majority of which contain a significant amount (ϳ0.2 pct) phosphorus removal. of phosphorus, which is reduced almost completely during Injection involves initial transportation followed by dissmelting reduction from its oxides. In India, low phosphorus charge of compressible fluid-mixed particles as a submerged ores deplete fast and the high carbon ferromanganese projet in the liquid metal. The process demands injection of duced will continue to have a phosphorus content greater powder using a minimum amount of carrier gas. The carrier than 0.4 pct. The situation is no better around other parts gas stream mixed with powder overcomes the resistance due of the globe. Unfortunately, there is no economically viable to the hydrostatic head, and upon leaving the outlet dipped process available to date that can be used by the ferromangain the liquid metal, develops a reverse motion due to buoynese industry. Some recent studies [1,2] have established the ancy and breaks into bubbles due to the hydrostatic head, feasibility of dephosphorization of high carbon ferromangasurface tension, and drag forces. The bubble size increases nese using BaO as well as BaCO 3 -based powders, but the with the decrease of hydrostatic head and bubbling improves time required to achieve the required level of dephosphorizathe kinetics of treatment of liquid metal. The amount of solid tion was more than 30 minutes in stagnant melt. Th...

Desulphurisation of Stainless Steel by Using CaO^|^ndash;Al2O3 Based Slags during Secondary Metallurgy

“…This can be understood with 1) the visual observation that bottom Ar blowing pushed the top slag onto the crucible wall, reducing slag/steel contact area, and 2) the aluminium would react with oxygen in Ar gas, resulting a high content of Al2O3 in slag (see in Tables 5 and 6) and consequently decreasing the sulphide capacity and sulphur distribution ratio, both of the decreasing of contact area and sulphide distribution ratio weaken the desulphurisation kinetics; (3) the desulphurisation rate decreases with decreasing the sulphur content in the steel, implying a difficulty for ultra-low sulphur steel refining; (4) with a similar mass transfer coefficient of sulphur in the slag phase, a high equilibrated sulphur distribution ratio between slag and steel could result in the fast desulphurisation rate. Furthermore, the fitted mass transfer coefficients of sulphur in slag phase are in the same order of magnitude obtained by other researchers, 3,18) suggesting a promising application of the present kinetic model. A relatively lower mass transfer coefficient is obtained in Test No.…”

“…However, the slag additions, in present tests, can result in the change of interface velocity and this would result in a change in the Sherwood number. Moreover, the sulphur diffusion coefficient in slag phase is a function of slag chemistry, 18) which varies with slag additions during the treatment. Therefore, the model is fit to the experimental data by obtaining the best fit values for the total mass transfer coefficients.…”

“…According to a number of previous studies, 3,5,18) transfer of (S) from the interface towards the bulk of the slag is substantiated to be the rate-limiting step of the desulphurisation reaction. Therefore, the desulphurisation rate can be expressed in term of the flux of (S) in the slag phase, which can be written as Eq.…”

Desulphurisation and Inclusion Behaviour of Stainless Steel Refining by Using CaO–Al2O3 Based Slag at Low Sulphur Levels

“…Based on the results of both the industrial and laboratory tests, it can be concluded that the present synthetic CA slag is feasible for the low sulphur stainless steel refining process. (4) the fitted mass transfer coefficients of sulphur in slag phase is 1.2 × 10 -6 m/s, which is in the same order of magnitude obtained by other researchers, 8,12,21) suggesting the reliability of the present kinetic model.…”

A Mathematical Model of Desulphurization Kinetics for Ultra-low-sulfur Steels Refining by Powder Injection during RH Processing

“…The rate-limiting step is the transfer of [S] from liquid steel towards the slag-steel interface 17,24) or (S 2 − ) from the slag or injected powders towards the interface. [25][26][27][28] …”