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Col. Bosques de las Lomas, Mexico

Maldonado-Parra F.D.,National Autonomous University of Mexico | Ramirez-Argaez M.A.,National Autonomous University of Mexico | Conejo A.N.,Morelia Technological Institute ITM | Gonzalez C.,National Autonomous University of Mexico
ISIJ International | Year: 2011

Gas injection in metallurgical vessels is an important tool to improve chemical and thermal mixing. Chemical mixing has been extensively studied in the past 40 years, however, thermal mixing is still poorly understood. This work reports a mathematical model developed to describe the effect of the number and position of porous plugs on thermal and chemical mixing under industrial conditions. A relevant contribution of this work is the evidence indicating a suppressing effect of bottom gas injection on thermal homogenization with off-center gas injection; furthermore, it also suggests that mixing time is optimized with only one nozzle instead of two or three. © 2011 ISIJ.


Ramirez-Argaez M.A.,National Autonomous University of Mexico | Conejo A.N.,Morelia Technological Institute ITM | Lopez-Cornejo M.S.,Ternium
ISIJ International | Year: 2015

The sponge iron or Direct Reduced Iron (DRI) is an important feedstock in the Electric Arc Furnace (EAF). The main sources of iron units for the EAF can be steel scrap, DRI, hot metal and combinations of these materials. The EAF has become a melting reactor and its melting rate plays a key role in furnace productivity. In this work, the melting rate of porous metallic particles is analyzed employing CFD tools, having the computational domain of an industrial size EAF. The molten pool is comprised of two liquid phases, steel and slag. In order to compute the melting rate as a function of particle size and arc length, three sub-models were developed, one computes the instantaneous power delivery as a function of arc voltage and arc length, the second one computes the velocity and temperature fields and finally the third sub-model computes the melting rate. Comparisons of melting rates when the particles are immersed in its own melt and the case where immersion is carried out in the steel/slag system is included in the analysis. A contribution from this work is a more realistic approach to compute the convective heat transfer coefficient using the estimated values of the velocity fields. © 2015 ISIJ.


Sanchez J.L.G.,Morelia Technological Institute ITM | Conejo A.N.,Morelia Technological Institute ITM | Ramirez-Argaez M.A.,National Autonomous University of Mexico
ISIJ International | Year: 2012

Recent Electric Arc Furnaces are equipped with ultra high power transformers to provide maximum values of electric power and minimize the melting time. The active power is increased by increasing arc length and arc voltage, however in these conditions energy losses due to radiation can also be increased with a consequent decrease in thermal efficiency. The energy radiated from the electric arcs is transferred to the walls inside the EAF promoting hot spots which represent a catastrophic operational condition. This work reports a radiation model which describes the formation of hot spots as a function of arc length and foamy slag height in an industrial EAF of 210 ton. of nominal capacity. Temperature profiles on the surface of the water cooled panels and values for the incident radiation were computed as a function of foamy slag height, used subsequently to define conditions to eliminate the formation of hot spots. © 2012 ISIJ.


Gonzalez O.J.P.,Morelia Technological Institute ITM | Ramirez-Argaez M.A.,National Autonomous University of Mexico | Conejo A.N.,Morelia Technological Institute ITM
ISIJ International | Year: 2010

Fluid flow and mixing phenomena in an industrial three phase Electric Arc Furnace has been investigated, as a function of arc length. Velocity and temperature fields as well as mixing times were computed, assuming that liquid steel occupies the whole computational domain and buoyancy forces are responsible for convective flow, it is reported a strong effect of arc length on both fluid flow and mixing time, suggesting a metallurgical practice with long arc operation to improve the melting kinetics of the metallic charge. Thermal stratification has also been confirmed, however the volume of hot steel increases when arc length also increases.


Gonzalez O.J.P.,Morelia Technological Institute ITM | Ramirez-Argaez M.A.,National Autonomous University of Mexico | Conejo A.N.,Morelia Technological Institute ITM
ISIJ International | Year: 2010

A computational fluid dynamics model coupled to a lagrangian model of melting/solidifying particles has been developed to describe the melting kinetics of metallic particles in an industrial Electric Arc Furnace (EAF), assuming that liquid steel occupies the entire computational domain. The metallic particles represent Direct Reduced Iron (DRI). The use of two previous models, an arc model and a fluid flow model has made possible to evaluate the melting rate of injected DRI in a three phase-EAF, evaluating the influence of the initial particle size, the initial DRI temperature, feeding position, feeding rate, arc length and some of the metallurgical properties of DRI. The frozen shell formed in the early stage of the melting process has also been evaluated in this model.

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