FeO Content In Slag Research Articles

Study on the Dephosphorization in Basic Electrode Welding

The process of dephosphorization for basic electrode and distribution of phosphours between slag and deposited metal(Lp) in manual metal arc welding has been researched by means of experimental and theortical analyses. The results indicate that P content in deposited metal decreased with the increase of coating basicity of the electrode and FeO content in slag. The distributive coefficient of phosphorus Lp increased with the increase of coating basicity of the electrode and FeO content in slag. Although dephosphprylation in deposited metal was a limit finally, it was satisfactory under suitable selsction of the value of FeO in slag and coating basicity of the electrode according to the experimental results.

Interaction mechanism between refractory and melts in iron bath smelting reduction process

The corrosion behavior of three sorts of refractories based on alumina-graphite were studied by immersion tests. The melts included smelting reduction molten slag and corresponding carbon saturated molten iron. The influence of test temperature, FeO content in slag and specimen rotative velocity on the corrosion rate of refractories was examined. By means of SEM and EDS, the microstructure change of the refractories after immersion test in kinds of melts was studied. The morphology of the deteriorated layer showed the corrosion extent of refractories. With the addition of zirconia and titania into the refractories, the corrosion rate changed to some extent. The corrosion rate of three sorts of refractories increased dramatically with the increasing FeO content in smelting reduction slag. Compared with alumina-graphite refractory and alumina-graphite-zirconia refractory, alumina-graphite-titania refractory had stronger corrosion resistance in the smelting reduction conditions. By the results of SEM and EDS, the corrosion mechanism of refractories was developed.

Mathematical Modelling and Experimental Investigation of Coke Reduction of FeO in Slag

Mathematic model development and experimental investigations were carried out for the reduction of FeO in slag by coke. Rate expressions for the reduction limited by the different steps and through different reaction routes were proposed. In the experimental investigation, the FeO reduction was found to be a first order and irreversible reaction; the reduction rate increased with increasing temperature and the FeO content in slag, and decreased with increasing ash content in the coke. Low CO2/CO ratio in the product gas and preferential reduction of FeO over SiO2 in slag were observed in the reaction system. The proposed reaction mechanisms were discussed with the observed kinetic phenomena. The reduction of FeO in slag by coke was found most likely to be jointly dominated by the mass transfer of FeO in slag and the chemical reactions at slag‐coke, slag‐gas or slag‐metal interfaces.

Production of high titania slag by Electro-Slag Crucible Melting (ESCM) process

In this research, ilmenite concentrate of Iran region successfully was smelted by Electro-Slag Crucible Melting (ESCM) process to produce TiO 2-rich slag as primary product and pig iron as by-product. Moreover, effects of reductant (carbon) amount and smelting time on TiO 2 and FeO content of slag and iron recovery were studied. It is found that addition of carbon excess to stoichiometric amount decreases the iron recovery and TiO 2 content in slag. If the smelting time keeps between 0 to 17 min, the TiO 2 content and iron recovery will be increased, whereas smelting time in excess of 17 min will cause products decline significantly. At optimum conditions, TiO 2 content in slag and the iron recovery are 70 wt.% and 84%, respectively. Kinetic studies proved that the reduction of equivalent FeO was first-order reaction. The studies made by X-ray diffraction analysis showed that formation of the titanium sub-oxides (Ti 3O 5 and Ti 2O 3) causes the decrease in iron recovery and TiO 2 content.

Effect of MgO and Al2O3 variations in oxygen steelmaking (BOF) slag on slag morphology and phosphorus distribution

Operational data of BOF and the slag samples for different starting conditions of phosphorus (0.06–0.26%P) and silicon content (0.3–1.2%Si) of hot metal have been analysed. The contribution of parameters which are well known to affect phosphorus distribution at tap, such as basicity, temperature, FeO content of slag, slag mass etc., is investigated through models of the ionic theory of slag, optical basicity, regular solution approach, and molecular theory of slag. The best overall results are obtained by the model based on the molecular theory of slag in which several operational parameters are also incorporated. Investigations of different slag samples, based on optical, SEM, EPMA and X-ray studies, reveal the effect of MgO and Al2 O3 on slag morphology and phosphorus distribution in different phases. It is important to consider the phosphorus distribution ratio in the solid and liquid part of the slag. The solid part of the slag, which is mostly dicalciumsilicate, can contain up to 5% phosphorus. The phosphorus content of the liquid part of the slag may depend upon the phosphorus content of the hot metal or the phosphorus load of the slag. It is found that incorporation of the effect of dicalciumsilicate in the model improves the accuracy of prediction. For better process control the addition of iron ore towards the end of the blow must be avoided while treating high phosphorus hot metal or during the production of ultralow phosphorus steels.

A model of reoxidation from the top slag and the effect on sulphur refining during vacuum degassing

A 2‐dimensional fluid‐flow model covering 3 phases (steel, slag and gas) has been augmented to include thermodynamic equations to study simultaneous reoxidation and desulphurization, including macro kinetic behaviour. The numerical simulations were isothermal. Predicted steel and slag component concentrations were compared with plant data from vacuum degassing and the agreement was found to be quite good. When the initial FeO content in the slag was increased, the predicted desulphurization rate decreased, the final sulphur content in the steel increased, and aluminium loss increased. When the temperature was increased, the predicted aluminium loss decreased somewhat. The effect of changes in temperature on the predicted final sulphur content was influenced by the initial FeO content in the top slag. The results show that the model can be used for future work on the dynamic modelling of slag/metal reactions if the initial FeO content is less than 3–4% (by weight).

Thermodynamic Study on MnO Behavior in MgO-saturated Slag Containing FeO.

In order to understand the behavior of manganese oxide in smelting reduction process, the manganese equilibrium between ironmaking slag containing FeO and silver melt was investigated over the temperature range of 1400-1500°C. The oxygen partial pressure was controlled by CO/CO2 ratio. Test results on Mn content in silver have been thermodynamically converted into those in supercooled or carbon-saturated iron melts and the activity coefficient of MnO in slag was determined experimentally. The activity of MnO decreased with increasing FeO content in slag. Higher FeO content as well as lower slag basicity resulted in larger equilibrium manganese distribution ratio between slag and iron. The temperature dependence of equilibrium manganese distribution was determined in the temperature range of 1400-1500°C. The relative partial molar heats of solution of MnO and Mn were also experimentally determined.

Some observations on current transfer at iron/calcium fluoride electrodes – Model experiments for current transfer in the ESR process

Measurement of current density‐potential curves with direct and alternating current at iron electrodes immersed into CaF2 or CaF2/10wt.% CaO slag. Theoretical interpretation of overpotentials in low current range. Dependence of overpotential on FeO content of slag.

転炉におけるスラグ中酸化鉄と鋼中酸素の関係について

The relation between iron oxide in molten slag and oxygen in molten metal in 160 t LD converter are studied, and the main results obtained are as follows.(1) During the period between end point and tapping the oxygen content in molten metal changes in a range of ±150ppm in low carbon steel (0.04%-0.08%C).(2) This change of oxygen in molten metal depends on the total FeO content of molten slag. When the total FeO content in slag is high, oxygen content in metal increases between end point and tapping. On the other hand, when the total FeO content is low, the oxygen content decreases.(3) At the end of oxygen blowing the slag temperature is higher than that of metal. The difference in temperatures seems to be over 50°C. This difference, however, vanishes during the period between the end point and tapping. This decrease of slag temperature after the end of blowing reduces the oxidizing potential.(4) As a consequence, the oxidizing potential of slag becomes lower than that of metal at tapping. In the smelting of low carbon steels, this phenomenon is observed in approximately one third of the heats, but scarcely in medium and high carbon steels.