Slag resistance mechanism of MgO–Mg2SiO4–SiC–C refractories containing porous multiphase aggregates

The slag resistance of MgO–SiC–C (MSC) refractories should be improved because of the mismatch in the thermal expansion coefficient between the aggregates and matrix, as well as the defects caused by the affinity between periclase and slag. In this study, MgO–Mg₂SiO₄–SiC–C (MMSC) refractories were prepared using porous multiphase MgO–Mg₂SiO₄ (M-M₂S) aggregates to replace dense fused magnesia aggregates. Compared to MSC, the slag penetration index of MMSC decreased by 43.5%. The structure of the porous aggregates increased the surface roughness, and the multiphase composition of the aggregates decreased the mismatch of the thermal expansion coefficient with the matrix, thus reducing debonding between the aggregates and matrix. The aggregates and matrix in the MMSC formed an interlocking structure, which bound them more tightly to improve the slag resistance. The slag viscosity at different depths from the initial slag/refractory interface was calculated using the Ribond model. The M-M₂S aggregates increased Si_xO_y^z− in the slag, which increased the slag polymerization and slag viscosity. The aggregates and matrix in the MMSC reacted with the slag to form high melting point phases, which reduced the channel of the slag. In addition, the penetration depth and velocity derived from the Washburn Equation were modified for the CaO–SiO₂–Al₂O₃–MgO–FeO slag and magnesia based refractory to accurately evaluate slag penetration.     

Corrosion modeling of magnesia aggregates in contact with CaO–MgO–SiO2 slags

Ladle refining is an efficient process for improvement of quality of steel on secondary metallurgy under harsh conditions. Magnesia refractories with high purity are important raw materials for ladle lining in high-quality steel production. However, the penetration by CaO–MgO–SiO₂ slags damages magnesia refractories, which considerably limits their service life. Abundant grain boundaries in magnesia create channels for slag penetration and lead to the destruction of the structure. The effect of the microstructure on the slag corrosion behavior of magnesia aggregates requires further systematic investigation. In this study, a corrosion model was established to describe the slag penetration process of magnesia aggregates. The effects of the grain-boundary size and slag CaO/SiO₂ mass ratio (C/S ratio) on slag penetration were investigated, and the possibility of the microstructure optimization of magnesia aggregates was discussed. The results indicated that magnesia aggregates exhibited excellent slag resistance for slag with a C/S ratio above 1.5 or even 2.0. When the slag C/S ratio was lower than 1.5, the dissolution rate of magnesia decreased more rapidly with the increase in the slag C/S ratio. In addition, the much smaller grain-boundary size increased the slag penetration resistance by promoting the formation of a dense isolation layer and inhibiting further penetration processes. The calculation results agreed well with the experimental results, suggesting that the corrosion model is promising for predicting slag corrosion.     

Comparative study of B4C,Mg2B2O5, and ZrB2 powder additions on the mechanical properties,oxidation, and slag corrosion resistance of MgO–C refractories

Boron-containing additives are used to improve the oxidation resistance of carbon-containing refractories; however, their effects on the mechanical properties and slag corrosion resistance of the refractories have rarely been studied. In this work, B₄C, Mg₂B₂O₅, and ZrB₂ powders were incorporated into low-carbon MgO–C refractories to study their effects on the mechanical properties, oxidation resistance, and slag corrosion resistance of the refractories. The relationships between these properties and the microstructure and phase evolution were also studied. The results show that the flexural strengths of the MgO–C refractories at high temperatures are closely related to the apparent porosity and formation of an Mg₃B₂O₆ phase. The oxidation resistances are greatly improved after the introduction of boron-containing additives into the MgO–C refractories in terms of both thermodynamical aspects and the filling of voids and pores. The most effective antioxidant is B₄C, followed by the ZrB₂ and Mg₂B₂O₅ powders. The mechanisms through which the vanadium-containing slag attacks the MgO–C refractories mainly include the dissolution of magnesia to form melting phases, penetration through pores, and redox reaction with carbon.     

Penetration and corrosion of magnesia grain by silicate slags

Abstract

Penetration and corrosion resistance of high purity sintered and fused magnesia grain by model EAF (CaO/SiO₂ = 1·38) and BOF ‘late’ slags (CaO/SiO₂ = 3·29) at 1600 and 1700°C were investigated by SEM, EDS, and XRD analysis. Thermodynamic calculations were performed to assist interpretation of the reaction processes involved. At the test temperatures, Fe andMn ions from both model slags diffused into themagnesia grain to form a magnesiowustite, (Mg,Fe,Mn)O. The magnesiowustite directly adjacent to the slag had a much larger crystal size than that of the bulk MgO far from the MgO/slag interface. The large magnesiowustite grains limit the potential for grain boundary penetration into the sintered magnesia. The magnesiowustite layer formed with the EAF slag took up more Fe_xO from the slag than that formed with the BOF slag, which was partially responsible for a lower slag penetration into sintered magnesia grain since the remaining silica rich local liquid was rendered more viscous. The EAF slag was not saturated with respect to MgO, so the magnesiowustite which did form later reacted with Ca and Si ions remaining at the MgO/EAF slag interface to form low melting phases such as merwinite, C₃ MS₂, and then dissolved into the slag, rendering the dissolution process essentially indirect. The BOF late slag was already oversaturated with respect to MgO, so slag penetration only occurred in the sintered magnesia grains.     

Interaction of Al2O3-rich slag with MgO–C refractories during VOD refining—MgO and spinel layer formation at the slag/refractory interface

The interaction mechanisms between a pitch-bonded MgO–C refractory and an Al₂O₃ rich (～15 wt%) stainless steelmaking slag were investigated by rotating finger tests in a vacuum induction furnace. A porous MgO layer (instead of a dense MgO layer) was observed at the hot face of the MgO–C bricks. This implies that under the present low oxygen pressure conditions, the oxygen supply from the slag is insufficient to meet the demand of reoxidising the entire amount of Mg vapor generated from the MgO–C reaction to form a fully dense MgO layer. A Mg(Al,Cr)₂O₄ spinel layer with zoning was found at the slag/brick interface in the top slag zone specimen of Test 3 (CHS3). Based on the thermodynamic analyses with and experimental data, a mechanism of Mg(Al,Cr)₂O₄ spinel formation is proposed. Initially, hot face periclase grains take up Cr₂O₃, and to a much lesser extent, Al₂O₃ from the slag. The further diffusion of Cr₂O₃ and Al₂O₃ from the slag establishes a spinel layer of three distinct compositions of the type MgAl_2(1?x)Cr_2xO₄, with x decreasing when moving from the interior to the exterior spinel layer. Due to the low oxygen pressures, the thermodynamically less stable, dissolved Cr₂O₃ in the hot face periclase decomposes and forms chromium-rich metal droplets.     

Mg(OH)2 Nucleation and Growth Parameters Applicable for the Development of MgO‐Based Refractory Castables

MgO is a very attractive raw material for refractory applications. However, its use has been mainly aimed at developing high‐magnesia and magnesia–carbon bricks due to the marked hydration likelihood of this oxide and the related drawbacks (volumetric expansion, crack formation) associated with this transformation. This work aims to evaluate some critical aspects that affect the MgO reaction with water (magnesia source, particle size, concentration of available sites for brucite nucleation, influence of a hydrating additive – acetic acid, and others) during the curing and drying steps of Al₂O₃–MgO binder‐free refractory castables. The attained experimental results were associated with the boundary nucleation and growth model proposed in the literature. According to the in situ elastic modulus measurements carried out at 110°C, the MgO particle size and reactivity present an important effect on the nucleation and growth of brucite crystals, highlighting that a proper site activation should be induced during the castables' curing process in order to effectively allow the use of magnesia as a binder source for refractories. Faster Mg(OH)₂ nuclei generation also helps to minimize further growth of these crystals, leading to a decrease in the samples' porosity and, consequently, a continuous increase in the overall refractory stiffness (E values).     

Corrosion of chemical-mineralogical gradient submicron-porous Al2O3-MgAl2O4 composite in contact with molten converter slag

Penetration resistance and corrosion mechanism of a novel chemical-mineralogical gradient submicron-porous corundum-spinel composite (A90) to converter slag were investigated and compared to its dense corundum counterpart. Slag-penetration resistance of A90, due to its special submicron-pore structure, is superior to that of the corundum counterpart. Gradient Al₂O₃-rich spinels pre-embedded on the inner-surfaces of the pores are essential for making the slag deficient in Fe²⁺ and Fe³⁺ and CaO-rich. The resultant CaO-rich slag reacted with the corundum matrix of A90, building up a continuous dense layer composed of tightly interlocked highly refractory tabular CaA1₁₂O₁₉ and thus suppressing the further slag penetration and corrosion. Due to the lack of MgO in the corundum/molten-slag reaction system, large amounts of low melting iron oxides still remained in the liquid slag, making it much less viscous, so it could penetrate readily the corundum substrate via the grain boundaries in it at the test temperature.     

Effects of different particle size of spinel and Y2O3 additive of the periclase-spinel refractory on the sintering densification and corrosion resistance to copper smelting slag

In order to analyze the sintering densification and copper smelting slag corrosion resistance of periclase-spinel refractories, the periclase-spinel refractories were prepared with fused magnesia, magnesia-rich spinel, industrial alumina, and yttrium oxide as the main raw materials. The different particle sizes of spinel in material and with or without Y₂O₃ additive were studied. The study demonstrated that: (1) The different particle sizes of spinel in periclase-spinel refractories can result in different effects. Adding particle spinel to the refractory can improve the strength and corrosion resistance of the periclase-spinel refractories. The addition of spinel and magnesia powders in the matrix resulted in cracks due to the great difference of coefficient of thermal expansion between magnesia and spinel. The reduction in bulk density and strength of the material decreased slag penetration resistance because of its poor sintering properties. While adding the alumina in the matrix can further fill the crack and prevent slag penetration by the volume expansion of in-situ reaction to form spinel. (2) The periclase-spinel refractories can be reacted with Cu slag to form a Mg₂FeO₄ insulating layer as the iron ion becomes oxidized. Adding Y₂O₃ in periclase-spinel refractories can result in grain boundary phase reconstruction, which can promote sintering densification, improve the slag physical infiltration resistance, and improve the chemical corrosion resistance of materials.     

Interfacial reaction between magnesia refractory and “FeO”-rich slag: Formation of magnesiowüstite layer

This study investigated the reaction between CaO-SiO₂-Al₂O₃-xFeO-MgO-MnO (CaO/SiO₂?=?1.2, x?=?20–50?wt%) slag and magnesia refractory. Using SEM-EDS analysis, we confirmed the formation of a (Mg,Fe)O_{ss(solid_solution)}, called magesiowüstite (MW), intermediate layer at the slag-refractory interface. MgO dissolved from refractory and reacted with the bulk slag to form MW layer at the interface. Simultaneously, slag penetrated through micro-pores and reacted with the refractory to form MW layer. In other words, the MW layer built up in both directions from initial refractory-slag interface. The thickness of the MW layer increased as the FeO content in the slag increased, and using EDS line scanning, a Mg and Fe concentration gradient was confirmed within the MW layer. The slag, which penetrated into the refractory, had a chemical composition of the CaO-SiO₂-Al₂O₃-MgO system without FeO, indicating that FeO was consumed by forming a MW layer at the refractory hot face. The slag-refractory interfacial reaction was simulated using thermochemical software, FactSage?7.0. The results predicted a MW monoxide composed of MgO and FeO. A spinel phase was formed when FeO was greater than 40?wt%. These thermochemical computations were comparable to our experimental findings.     

Interfacial reactions between magnesia refractory and electric arc furnace (EAF) slag with use of direct reduced iron (DRI) as raw material

Interfacial reactions between the electric arc furnace (EAF) slag, i.e., CaO–SiO₂–FeO–MgO–Al₂O₃–MnO system, and the magnesia refractory as a function of direct reduced iron (DRI) addition (0, 10, 20, 30 wt%) were investigated at 1550 °C under an Ar atmosphere. MgO solubility increases with increasing DRI content by decreasing basicity (i.e., CaO/SiO₂ ratio), which is due to an increase in SiO₂ supplied from DRI. The measured MgO content was always lower than the theoretical MgO saturation level irrespective of DRI content because the magnesiowüstite (MW) intermediate layer, which formed at the slag/refractory interface, retarded the direct dissolution of the refractory by acting as a self-protective layer. The thickness of the MW intermediate layer and dissolution depth were proportional to DRI content. However, the penetrativity decreased with increasing DRI content by decreasing the fluidity of the slag. Several kinetic parameters were estimated, including the dissolution rate constant of the MW intermediate layer, the dissolution rate of the MgO refractory, and the rate constant of MW growth. Dissolution of MgO refractory is controlled by the dissolution of the MW intermediate layer. Increasing the growth rate is very important for protecting refractory after the formation of a MW intermediate layer. In addition, we provided a schematic diagram of the slag/refractory interfacial reaction phenomena that compares situations of low and high DRI content. The results of the present study show that it is necessary to control DRI content to minimize refractory degradation during the EAF process. If a large amount of DRI must be used in the EAF process, then MgO content in the slag should be at the saturation limit at first, which accelerates growth of the MW intermediate layer.     

Degradation mechanisms of magnesia-carbon refractories by high-alumina stainless steel slags under vacuum

The corrosion behaviour of a pitch-bonded magnesia-carbon refractory by an Al₂O₃ rich (∼15 wt.%) stainless steelmaking slag was investigated by rotating finger tests in a vacuum induction furnace at high temperature (>1650 °C) and low oxygen partial pressure (1.5–4.3 × 10⁻¹⁰ atm). This study confirms the poor slagline behaviour of MgO-C bricks industrially observed in VOD ladles. Higher temperatures and longer exposure times lead to more severe slag infiltration and direct MgO dissolution. The intrinsic MgO-C reaction is the major decarburisation mechanism, while extrinsic decarburisation by oxygen from the atmosphere and/or reducible slag components (CrO_x, FeO_x) was limited. Three kinds of metallic particles with different size, shape, location, composition and origin were observed in the refractory specimens. Concurrently, the thermodynamic conditions for the formation of a protective Mg(Al,Cr)₂O₄ spinel layer at the slag/refractory interface are investigated. The industrial relevance of this spinel layer formation is discussed with respect to the chosen Al₂O₃ level. Guidelines are proposed to minimise MgO refractory dissolution in VOD slaglines.     

Effect of electromagnetic field on slag corrosion resistance of low carbon MgO–C refractories

Using MgO–C refractories containing 6% carbon and the slag with a basicity (CaO/SiO₂) of around 0.8, the melting slag resistance experiments of low carbon MgO–C refractories were carried out in induction furnace and resistance furnace, respectively. The microstructure of low carbon MgO–C refractories corroded by slag under the different conditions was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDAX). The results show that in induction furnace having electromagnetic field (EMF), there are MgFe₂O₄ spinel with a little of Mn ions generated in the interfacial layer. Part of the solid solution is monticellite [CaMgSiO₄] containing a little MnO and FeO. While under the condition of EMF free, there is not MgFe₂O₄ spinel in the interfacial layer and the solid solution is monticellite (CaMgSiO₄). At a high temperature, EMF increases the diffusion coefficient of Fe^2+/3+ ions, which displaces Mg²⁺ and forms MgFe₂O₄ with a little of Mn ions. There are MgAl₂O₄ spinel in the penetration layers under the conditions of both EMF and EMF free. EMF speeds up corrosion of low carbon MgO–C refractories.     

Effect of carbon black on corrosion resistance of Al2O3–SiC–C castables to SiO2–MgO slag

Metallurgical solid waste recycling is the shape of things to come in green development of Chinese iron and steel industry. Utilization of ironworks slag for producing mineral wool at high temperature is an important approach. However, refractory lining is seriously corroded by the SiO₂–MgO based slag at 1600 °C during the production process. Different production steps need different atmospheres, the changeable service atmospheres (air and reducing atmosphere) put forward high requirements for slag resistance. The Al₂O₃–SiC–C castables containing carbon black are usually used in iron runner, which faces high-temperature service condition of 1450 °C–1500 °C. Nevertheless, the function of carbon black in the Al₂O₃–SiC–C castables at 1600 °C is till essentially unknown. In the current study, the carbon black was introduced to tabular alumina based Al₂O₃–SiC–C castables to improve corrosion resistance to SiO₂–MgO based slag at 1600 °C. The result showed that 0.4 wt% carbon black was suitable for the castables, which the slag resistance of castables was significantly improved. The carbon black had contributed to block slag by wettability resistance. By comparison with the castables without carbon black, the corrosion index and penetration index had been reduced by 20.2% and 28.0%, respectively, under air atmosphere. And there were little corrosion or penetration under reducing atmosphere for castables with 0.4 wt% carbon black. For the mechanical properties, the Al₂O₃–SiC–C castables with 0.4 wt% carbon black could serve production process although the carbon black impaired the physical properties.     

Role of Mg(OH)2 in pore evolution and properties of lightweight brine magnesia aggregates

Lightweight magnesia aggregates were fabricated using high-purity MgO agglomerates with the addition of Mg(OH)₂ as a pore former. The pore evolution and its relationship to the resulting properties were investigated. Mg(OH)₂ decomposition increased the number of inter-agglomerate pores, which subsequently affected the porosity and pore structure. When Mg(OH)₂ was 0–20 wt%, the inter-agglomerate pores were converted to both open and closed small pores, which effectively reduced the thermal conductivity and improved the thermal shock resistance (TSR) by accommodating thermal stress and inducing crack deflection. Small pores also favored the formation of a dense (Mg, Fe)O corrosion layer, preventing further slag penetration. However, large open pores occurred with further increasing Mg(OH)₂ content, which dramatically deteriorated the TSR and slag resistance. The specimen with 20 wt% Mg(OH)₂ exhibited the best overall performance, with a thermal conductivity of 16.6 W/(m·K) at 500 °C, and a residual flexural strength ratio of 32.3%; its slag resistance was comparable with that of dense magnesia.     

Microstructure,properties, and application of low carbon Al2O3-C refractories used as submerged entry nozzles

With the aim to achieve the application of low carbon Al₂O₃-C refractory as submerged entry nozzle (SEN) materials, a comprehensive study on the microstructure, thermo-mechanical properties, as well as application performance during use in the continuous casting was carried out by comparing with the traditional one. Both hot and cold modulus of ruptures of the low carbon Al₂O₃-C refractory were superior to the traditional one, and its thermal shock resistance still kept in an acceptable level. The increase in the amount of SiC whiskers and the enhancement in the sintering are considered as the strengthening mechanism. In the industrial trial, the rapid loss of graphite caused by the large level fluctuation made the traditional Al₂O₃-C refractory more susceptible to flux corrosion. For the low carbon Al₂O₃-C refractory, however, the dense structure and the adhesion of viscous slag layer suppressed the slag penetration. Besides, the remaining SiC phases were also difficult to be wetted and dissolved by the flux. As a consequence, a better corrosion resistance was obtained, achieving a decrease of 27.6% in the average depth of the corrosion groove after working for 8 hous.     

Comparison study on effect of nano-sized Al2O3 addition on the corrosion resistance of microporous magnesia aggregates against tundish slag

The microporous magnesia aggregates show a promising application prospect as tundish lining, due to the excellent thermal insulation. In this study, the effect of nano-sized Al₂O₃ addition on the corrosion resistance of microporous magnesia aggregates against tundish slag is explored. The results show that the addition of nano-sized Al₂O₃ deteriorates the slag resistance of microporous magnesia aggregates, which is mainly because that the apparent porosity of aggregates increases with the addition of nano-sized Al₂O₃. Furthermore, MgO·Al₂O₃ spinel is formed in situ at the grain boundaries of Al₂O₃-bearing aggregates and the dissolution of MgO·Al₂O₃ spinel into molten slag damages the structure of aggregates. For the Al₂O₃-free microporous magnesia aggregates, as expected, the penetration of high basicity slag (CaO/SiO₂ = 9, mass ratio) into refractory is slighter than that of low basicity slag (CaO/SiO₂ = 4, mass ratio). But, for the Al₂O₃-bearing microporous magnesia aggregates, the corrosion of refractory by high basicity slag is severer. This is mainly because that MgO·Al₂O₃ spinel is more unstable in high basicity slag. Therefore, it is not suitable to add nano-sized Al₂O₃ for the preparation of microporous magnesia as tundish lining.     

Improvement of Durability of Purging Plugs Using MgO Micropowder for Refining Ladles

To modulate the matrix of purging plugs, MgO micropowder was introduced as a replacement to magnesia powder in alumina–magnesia castables, and the effect of MgO micropowder on the properties of alumina–magnesia castables and the possibility of developing chrome‐free castables were investigated. Experimental results showed that the introduction of MgO micropowder resulted in an improvement in the volume stability, strength, and thermal shock resistance of alumina–magnesia castables due to its high surface energy and small particle size. However, excessive amounts of MgO micropowder led to a lower densification, and there was a slight degradation in the performance of the alumina–magnesia castables. The slag resistance of the prepared alumina–magnesia castables was significantly better than that of the alumina–chrome castables. Microstructure and energy spectrum analysis showed that the formation of a solidified reaction layer, mainly consisting of spinel and CaAl₁₂O₁₉, was the major cause of the observed difference in slag resistance. In addition, the alumina–magnesia castables had a lower linear thermal expansion coefficient than that of the alumina–chrome castables at each experimental temperature, which effectively decreased the thermal stress during its service period, thus exhibiting good thermal shock resistance.     

Investigation of slag-refractory interactions for the Ruhrstahl Heraeus (RH) vacuum degassing process in steelmaking

In order to determine the effect of slag composition during the RH process on refractory wear, magnesia–carbon and magnesia–chromite refractories were immersed for 10 min at 1600 °C in a ladle slag, two FeO-rich slags (20 and 40 wt% FeO) and two CaO–Al₂O₃ slags. Corrosion of magnesia–carbon refractory by the ladle and CaO–Al₂O₃ slags was limited as the refractory carbon phase efficiently prevented slag infiltration. Severe degradation was observed in contact with FeO-rich slags. FeO oxidized the carbon phase with formation of Fe droplets at the hot face. Regarding magnesia–chromite refractory, the corrosion mechanism consisted of severe slag infiltration, high temperature inactivation of the secondary chromite and primary chromite dissolution in the infiltrating slag. The FeO-rich slags seem to have generated more severe conditions as the infiltrating slag pushed apart the periclase grains, leading to severe refractory erosion. The degradation mechanisms are discussed by combining experimental results and thermodynamic calculations.     

Resistance of 2ZrO2·Y2O3 top coat in thermal/environmental barrier coatings to calcia‐magnesia‐aluminosilicate attack at 1500°C

Internally cooled, hollow SiC‐based ceramic matrix composites (CMCs) components that may replace metallic components in the hot section of future high‐efficiency gas‐turbine engines will require multilayered thermal/environmental barrier coatings (T/EBCs) for insulation and protection. In the T/EBC system, the thermally insulating outermost (top coat) ceramic layer must also provide resistance to attack by molten calcia‐magnesia‐aluminosilicate (CMAS) deposits. The interactions between a potential candidate for top coat made of air‐plasma‐sprayed (APS) 2ZrO₂·Y₂O₃ solid‐solution (ss) ceramic and two different CMASs (sand and fly ash) are investigated at a relevant high temperature of 1500°C. APS 2ZrO₂·Y₂O₃(ss) top coat was found to resist CMAS penetration at 1500°C for 24 hours via reaction products that block CMAS penetration pathways. In situ X‐ray diffraction (XRD) studies have identified the main reaction product to be an Ca‐Y‐Si apatite, and have helped elucidate the proposed mechanism for CMAS attack mitigation. Ex situ electron microscopy and analytical spectroscopy studies have identified the advantageous characteristics of the reaction products in helping the CMAS attack mitigation in the APS 2ZrO₂·Y₂O₃(ss) coating at 1500°C. Finally, the Y³⁺ solubility limit and transport behavior are identified as potential comparative tools for assessing the CMAS resistance ability of top‐coat ceramics.     

High‐temperature calorimetric study of oxide component dissolution in a CaO–MgO–Al2O3–SiO2 slag at 1450°C

Blast‐furnace slags are formed, as iron ore is reduced to metal, as a molten a mixture of refractory and not easily reducible oxides, largely silica, alumina, lime, and magnesia. Their relatively low silica content makes them basic and poor glass formers. Their thermodynamic properties, though important for modeling their formation and reactivity, as well as furnace heat balance, are poorly known. Solution calorimetry of small amounts of solid oxides in a molten oxide solvent at high temperature (up to about 1500°C) permits direct assessment of energetics of dissolution. The enthalpies of solution of slag forming oxides: CaO, SiO₂, Al₂O₃, MgO, and Fe₂O₃ in a simplified model slag of composition: CaO (45.9 mol%), SiO₂ (35.1 mol%), Al₂O₃ (8.3 mol%), MgO (10.7 mol%) were measured by high‐temperature drop solution calorimetry at 1450°C. For this slag composition, enthalpies of solution become more exothermic in the order: Fe₂O₃ (279.3 ± 20.8 kJ/mol), MgO (56.7 ± 9.1 kJ/mol), Al₂O, (41.6 ± 11.3 kJ/mol), CaO (?4.3 ± 2.3 kJ/mol), and SiO₂, (?20.4 ± 4.4 kJ/mol), reflecting the relatively basic character of this low‐silica melt. Within these fairly large experimental errors, characteristic of calorimetry at this high temperature, there is little or no discernible concentration dependence for these heats of solution. The trends seen for these five solutes parallel those seen for heats of solution of the same oxides in other melts at various temperatures, with changes in magnitude reflecting the differences in acid‐base character of the melts. The new data for quartz show systematic behavior which extends the range of basicity studied for the enthalpy of dissolution of silica. The results provide reliable data for future modeling of the thermal balance of steel‐making furnaces and geologic and ceramic systems.