Corrosion Mechanism and Wear Prediction of the Sole of an Electric Arc Furnace.

Abstract

The solution of the corrosion problems in an electric arc furnace, like in most of the metallurgical reactors, has left overcoming through the repetition of trial and error tests. The basic knowledge of corrosion mechanisms is still very limited and does not allow to structure a specific analysis for each problem and thus to obtain qualitative and quantitative answers to scientific, technical and industrial problems. [1][2][3] The Nodal Wear Model NWM, has the objective to systematize a new line of knowledge and work in the corrosion of the refractory and ceramic materials in contact with corrosive fluids (metals, mattes and slags). Although the NWM has been initially developed in the study of corrosion profiles in a blast furnace, [4][5][6] it constitutes in itself a new tool for the knowledge of mechanisms involved in the wear of materials and provides an appropriate way to solve all those similar problems that the Pyrometallurgical Processes outlines to the modern Materials Science.The last years have shown a strong increase in the demand of ferritics products with very low carbon content. The ferroalloys that are needed to carry out the corresponding chemical adjustment in the secondary metallurgy have lower and lower carbon content specifications.The classical procedure for the fabrication of low carbon ferromanganese is shown in Fig. 1. In a first step, the manganese oxide from the feed (pirolusite, MnO 2 ) is reduced by a carbothermic reduction in an electric arc furnace. The ISIJ International, Vol. 43 (2003), No. 2, © September 28, 2002 ) There are many alternatives for the refractory lining in the sole of an electric arc furnace that produces refined ferromanganese, Fe-Mn (80 % with low carbon content, %CϽ1.5). Empiric approaches have usually been used for the design. Even though they allowed increasing the number of tapping, they are not base in a quantitative prediction of the wearing from the knowledge of a corrosion mechanism.This paper presents a quantitative prediction for the corrosion processes in two basic soles using the mathematical formulation of the Nodal Wear Model (NWM). In both cases, the equations that describe the corrosion are established and applied, according to the control mechanism of the corrosion, in each node of a Finite Element Model (FEM) grid of the refractory lining is in contact interface with the liquid ferroalloy.When the sole formed by a magnesite castable refractory (with a minimum content of 95% periclase), the penetration of the molten phase through the open porosity of the refractory controls the corrosion. In the case of a dolomitic sole (75 % MgO, 20 % CaO, 0.60 % SiO 2 , 3.80 % Fe 2 O 3 , Al 2 O 3 ϭ0.30 %), the corrosion rate is controlled by the diffusion of silicon, one of the active components of the refractory matrix, from each interfacial node in the sole to the molten phase.KEY WORDS: wearing; electric arc furnace; ferromanganese; mathematical modeling. molten alloy produced has about mass 75 % of Mn, and the carbon can reach up to 4 %.To reduce the ca...

Aplicación del MDN al estudio de la corrosión de los convertidores Peirce - Smith

“…A partir de la carga 80, sucede un nuevo proceso de infiltración capilar y el correspondiente ataque químico de la matriz refractaria controlado por la difusión de los productos de la corrosión a través e la costra, ecuación [2].…”

“…El desarrollo matemático del Mecanismo Capilar en la corrosión de materiales refractarios ha sido publicado en la referencia (2). Es preciso destacar en este caso que es más importante conocer la profundidad de la penetración del fundido, e c , que la velocidad bajo la cual se produce.…”

“…La ecuación que representa la velocidad de corrosión del refractario en metros por segundo, actuando como etapa lenta del proceso la difusión de las especies atacadas a través de la costra, Figura 3,es semejante a la utilizada para la simulación del desgaste en el crisol del alto horno (1) y (3): [2] si bien en este caso, L, es la profundidad alcanzada por el fundido en el refractario se identifica con e c , Figura 3. Igualmente, µ i , representa la viscosidad nodal del fundido, ρ i , la densidad nodal del fundido, D i , el coeficiente de difusión nodal del compuesto resultante del ataque químico a través de la costra, (∆%C) , el gradiente de concentración del compuesto resultante del ataque químico a lo largo de la costra en el nodo i, ρ g , la densidad global de refractario y % cm, el porcentaje del constituyente matriz en la estructura del refractario utilizado para el revestimiento.…”

Design of Blast Furnace Crucibles by Means of the Nodal Wear Model

“…NWM was designed to simulate corrosion profiles in blast and electric furnace crucibles, and has been recently applied to the analysis of wear in Pierce-Smith copper converter coatings. [3][4][5][6][7] However, one aim of this study is to make a much greater use of NWM by using its methodology to help decision making in selecting the material layout which should be most adequate for use in crucibles. NWM is incorporated into a finite element code, COSMOS/M in the present case, as this software provide the solution for the differential equations that describe the energy and mass transfer within the crucible.…”

Results of the Application of the Mdn in the Improvement of the Design of an Electrical Furnace that produces Low Carbon Ferromanganese

“…It is possible to state therefore that the furnace used for the manufacture of refined ferroalloy that was used until the year 2000, can be defined according to the previously mentioned criteria, such as model M (18; 5.0; 14-19). 1,3) In this model, the global heat transport coefficient from point 43 to point 14 of : is the maxima concentration of silicon in mass% (equilibrium concentration) in ferromanganese to the temperature of the node "i". The value of the maximum concentration of silicon concentration is tied to the following thermodynamic balance 4,6) :…”