Slag Resistance Research Articles

Effect of rare-earth oxide concentrate on reaction, densification and slag resistance of Al 2O 3SiO 2 ceramic refractories

Ceramic bodies of mullite composition were prepared from a mixture of calcined alumina and raw kaolin with the addition of bastnasite (rare-earth oxide concentrate) at up to 3% wt and fired at 1400–1650°C. The bastnasite addition effectively enhances mullite formation but the effect diminishes rapidly with increasing temperature. The Al 2O 3-rich composition is characteristic of the mullite. The ceramic green compacts with the bastnasite addition can only approx. reach 96% theoretical density at best when heated at 1550–1650°C. The pores in the fired bodies with the bastnasite addition are smaller and uniformly distributed; localized, larger pores are found in the fired bodies without the addition. The slag resistance of the refractories increases slightly with an increasing amount of bastnasite added to the bonding matrix. Bastnasite is not an effective additive for enhancing the slag resistance of steel-plant refractories. The peak temperature in DTA and the valley temperature in the dilatometric analysis, are indicative of mullite formation: the former was found to be 1412°C without bastnasite addition and 1368°C with 3% wt bastnasite addition while the latter was found to be 1420°C without bastnasite addition and 1350°C with 3% wt bastnasite addition.

Effect of Cr2O3 on Slag Resistance of Al2O3–SiO2 Refractories

Refractory bodies of 65 wt% Al2O3 were prepared from a mixture of calcined alumina and raw kaolin with the addition of Cr2O3 up to 15 wt%. The Cr2O3 addition effectively enhances slag resistance and reduces mullite formation. Petrographic analysis of the refractories after the slag test suggests that Cr2O3 increases the viscosity of both the glassy phase in the refractory as well as the slag, thereby retarding slag penetration and reaction at elevated temperature.

溶銅または溶鉄とCaO-Al<SUB>2</SUB>O<SUB>3</SUB>系スラグ間反応速度の電極インピーダンス法による解析

A chemical reaction at the interface between slag and metal can be analyzed as a kind of electrode reaction because of the ionic nature of liquid slag.In the present work, application of an A.C. impedance method to slag-metal reaction in iron- and steel-making process was tried to clarify the individual kinetic factors concerning the electrode reactions at the interface between slag and metal. The total impedance between CaO-Al2O3 slag and Cu-S or Fe-C-S melts was measured in this paper.The results obtained were successfully used to determine the individual factors on kinetics of the electrode reaction between slag and metal, such as solution resistance of slag, interfacial capacitance in electric double-layer, overvoltage of charge transfer, rate constant and so on.

A.C. Impedance Analysis of the Kinetics of Reactions between Molten Cu or Fe and CaO-Al2O3 Slag.

A chemical reaction at the interface between slag and metal can be analyzed as a kind of electrode reaction because of the ionic nature of liquid slag.In the present work, application of an A.C. impedance method to slag-metal reaction in iron- and steel-making process was tried to clarify the individual kinetic factors concerning the electrode reactions at the interface between slag and metal. The total impedance between CaO-Al2O3 slag and Cu-S or Fe-C-S melts was measured in this paper.The results obtained were successfully used to determine the individual factors on kinetics of the electrode reaction between slag and metal, such as solution resistance of slag, interfacial capacitance in electric double-layer, overvoltage of charge transfer, rate constant and so on.

Structure of the calcareous gunite-coatings of the linings of converters

A study of the structure of the calcareous gunite coatings before and after bringing them into contact with a lime-fayalite melt showed that due to the effect of high temperatures, a dense refractory coating forms at the surface of the lining. The obtained coating corresponds to the lime-periclase refractories with respect to composition. It exhibits high slag resistance, thermal shock resistance, and mechanical strength and improves the service life of the converters. The optimum specific consumption of oxygen was determined for carrying out guniting.

Correlation of geometric factor for slag resistance electric furnaces

The electric resistance of an industrial slag resistance furnace is an important factor in its design and operation. At a certain slag conductivity, the furnace resistance is dependent only on the furnace and electrode geometries; this geometric effect, usually called geometric factor, is a function of the electrode diameter, the depth of electrode immersion, the electrode spacing, and the total depth of slag layer. A correlation of the geometric factor to the above four geometric parameters was developed in this study on the basis of the measurements in a two-electrode salt-solution model. Comparison of the developed correlation to measurements in actual slag resistance electric furnaces shows good agreement between the calculated and measured values.

Slag resistance of corundum-graphite and periclase-graphite ramming bodies

We established a connection between the slag resistance and the absolute value for the difference in the mean atomic relative electronegativity of slag and refractory. An increase in the slag resistance with the addition of graphite, together with other factors, is caused by the impairment of the wetting capacity of the slag on the refractory surface.

ChemInform Abstract: Corrosion Resistance and Microstructure of High‐Alumina Refractories, Based on the Rotary Slag Test.

AbstractAnalysis of six different high‐alumina refractories after exposure to the rotary slag test shows that Cr2O3‐containing refractories have a better slag resistance than the Cr2O3‐free materials.

Use of graphite-containing nozzles for vacuum casting of ingots

At Izhorsk Plant Production Union in casting of ingots up to 150 tonnes in vacuum, chamotte nozzles with periclase inserts are used. In casting of ingots weighing more than 150 tons these nozzles erode strongly and this leads to interrupted teemings. In connection with this, work was done on selection of a nozzle material providing uninterrupted vacuum teeming of steel into large ingots. The use of zirconia-graphite nozzles to TU 14-8-238-77 was proposed for this purpose. Selection of the zirconia-graphite nozzle material was the result of its good metal and slag resistance, low wettability, and high heat resistance

Corrosion Resistance and Microstructure of High‐Alumina Refractories, Based on the Rotary Slag Test

The corrosion resistance and microstructure of four highalumina and two chromia‐containing high‐alumina refractories were evaluated. Analysis of the refractories after exposure in the rotary slag test showed that the chromia‐containing products had better slag resistance than the chromia‐free products. Three factors contributed to this conclusion, including formation of a Cr‐spinel layer at the slag/refractory interface, formation of an impermeable mullite layer just below the interface, and improved matrix bonding from chromia‐alumina solid‐solution formation.

Increasing the life of mixer-type molten iron transfer ladles

New forms of refractories, types of KPF-95 and MKFU-85, which possess increased mechanical srength, refractoriness, and slag resistance, were selected and tested for lining of mixers.

Slag resistance of aluminosilicate compositions with additions of silicon carbide

A method is proposed for measuring the rate of solution of refractory material in slag, consisting of the determination of the linear dimensions and mass of the original material, and its mass residue not dissolved in the slag.

Refractories for vacuum degassing of steel

New equipment for outside-the-furnace vacuum degassing of steel includes argon-oxygen refining units, circulation flow vacuum degassing units, and units for steel degassing in the ladle with electric arc heating. The refractories developed for use in this equipment include magnesia, periclase-carbon, corundum, alumina, periclase-lime, magnesia-dolomite, forsterite, and unformed and vibrocompacted refractories. The refractories were selected for heat resisting and thermal insulation applications. This paper reviews at length the raw material base, production processes, and applicable properties of these refractories under degassing conditions, including slag and silicate resistance, temperature and phase behavior, permeability, compression strength, service life, and wear behavior. In addition, specifications are given for a wide range of refractories and their applications in specific pieces of equipment. Savings in refractory and power consumption are discussed.

A study of protective plasma coatings

The specimens covered with plasma coatings have a denser structure and finer pores as compared to the refractory products used as substrates. Plasma coating of the specimens improves some of their important service characteristics such as slag resistance and gas permeability.

Slag resistance of refractories for evacuators

Resultats d'essais comparatifs de resistance aux scories de divers refractaires employes dans le traitement sous vide de l'acier

A Finite-Element Package for the Analysis of Electromagnetic Forces and Power in an Electric Smelting Furnace

In a conventional matte smelting or slag resistance furnace electrical conduction currents flowing in a molten slag are used to generate the required process heat. Such furnaces generally involve a 6-in line electrode geometry, with the electrodes generally being in excess of 1m diameter and the electrode currents being on the order of 100 kA. One of the principal electrical design problems is the calculation of the power and current distribution. These parameters directly influence the furnace operating practice and the design of the furnace electrical equipment and refractories. An additional design problem is that of refractory and electrode erosion due to the slag motion. The electromagnetic body forces are among the principle forces which drive the recirculatory slag flow. A finite-element numerical model, which determines the distribution of the furnace power and the electromagnetic body forces as a function of the furnace operating parameters is described. The advantages of this method over existing methods are described.

Service tests of chrome-spinel-periclase refractories

In chemical composition the experimental chrome-spinel-periclase refractories are characterized by a high degree of purity. The total content of impurity oxides of silicon, calcium, and iron does not exceed 2%. The parts possess increased density, porosity, and slag resistance but a lower heat resistance than the imported refractories with a silica content of 0.5%.

Slag resistance and deformation under load of rammed high-alumina mixtures for monolithic steel-teeming ladle linings

Slag resistance and deformation under load of rammed high-alumina mixtures for monolithic steel-teeming ladle linings

Effect of an addition of silicon carbide on the properties of a mullite-corundum tamping mass

On the basis of this study we have established that the addition of 10% SiC significantly increases the slag resistance of a mullite-corundum tamping mass and makes it possible to increase the stability and prolong the useful life of the lining; the thermal conductivity of the mass is also increased and provides it with a higher thermal-shock resistance with a reduction in the open porosity.

Refractories for Basic Oxygen and Electric Furnace Steel Making in the USA

In the USA since the use of BOF steel making has increased, the refractory technology had to keep up with the change. Common forms of refractories are either coal tar pitch-bonded or impregnated magnesite or less commonly dolomite, having varying contents of carbon (5–30%). The types of refractory grains—magnesite or dolomite—are described for best performance. Some critical properties of the bricks along with their slag resistance results are given. The use of refractories in BOF and AOD electric furnaces in various parts are described in some detail.