Effect Of Slag Composition Research Articles

Effect of ladle slag composition on the cleanliness of Al-Ti deoxidized interstitial-free steel

The effect of slag composition on the cleanliness of Al-Ti deoxidized interstitial-free steel produced via basic oxygen furnace (BOF)-ladle furnace (LF)-Ruhrstahl-Heraeus (RH)-continuous casting (CC) process was investigated by the systematic samplings and analyses for four heats in a steel plant in China. Oxygen/nitrogen analyzer, automatic scanning electron microscope, field-emission scanning electron microscope, and energy spectroscopy analysis were used to analyze the variations of number, size, type, and morphology of inclusions in molten steel from RH to tundish, and X-ray fluorescence was used to analyze the slag composition. The relationship between slag composition and inclusion characteristics in molten steel was investigated. The effect of slag composition on the oxygen mass transfer from the slag–metal interface to liquid steel was also studied through a theoretical calculation. The results showed that the cleanliness of molten steel was greatly affected by the slag composition. The deterioration of steel cleanliness was mainly arisen from a serious reoxidation of molten steel by oxidizing components like (T.Fe + MnO) in top slag during RH refining process. A weak ability to absorb inclusions of top slag with high CaO/Al2O3 and CaO/SiO2 mass ratios was confirmed from the inclusions analyses. The size and number of Al2O3 inclusion clusters were larger, and Ti content in Al2O3-TiO x inclusions was higher from RH to tundish in the case of serious reoxidation. The reduction of FeO content and keeping the CaO/Al2O3 and CaO/SiO2 ratios at about 1.6 and 4–7, respectively, in top slag during RH refining process was beneficial to minimize the reoxidation of Al and Ti and increase the inclusion absorption ability of top slag.

Effect of slag composition on kinetic behavior of deep deoxidation of 5 wt.% Si high-silicon austenitic stainless steel

Effect of slag composition on kinetic behavior of deep deoxidation of 5 wt.% Si high-silicon austenitic stainless steel

Effect of slag composition and current density on ingot cleanliness during low-frequency/DC electroslag process

Effect of slag composition and current density on ingot cleanliness during low-frequency/DC electroslag process

Experimental Study and Thermodynamic Modelling of Equilibrium Distributions of Ni, Sn and Zn Between Slag and Black Copper for E-Scrap Recycling Applications

The recycling of waste electronic and electrical equipment (WEEE) and other secondary copper-containing materials through the "black copper" process relies on the selective distribution of metals among the gas, slag, and copper-rich liquid phase. This distribution is controlled by the effective oxidation/reduction potential, often expressed in terms of oxygen partial pressure. Separation of Ni and Sn presents a certain challenge in recycling though black copper route due to similar distribution coefficients over a wide range of oxygen partial pressures and possibly can be improved by optimizing the slag chemistry. This study provides experimental information on the distribution of Ni, Sn, and Zn between fayalite slags or calcium ferrite slags and copper-rich metal at 1250°C. The study uses high-temperature equilibration, quenching, and electron probe X-ray microanalysis (EPMA) techniques along with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for selected measurements of low concentrations. The oxygen partial pressure is controlled by the CO/CO2/Ar gas flow or by measuring the concentration of copper oxide in the slag. The effect of slag composition in terms of Fe/SiO2 or Fe/CaO ratio is studied by using different holding materials, such as silica (SiO2) ampoule, solid spinel (Fe3O4), wüstite (FeO), or dicalcium ferrite (Ca2Fe2O5). The experimental results are compared with literature data and used to optimize thermodynamic models for FactSage® software. The results demonstrate an opportunity for more effective separation of Ni and Sn using at oxidizing stage by using calcium ferrite slag promoting the formation of Sn4+.

Effect of slag composition on corrosion resistance of high chromia refractory bricks for industrial entrained-flow gasifier

The slag composition corresponding to different coals varies significantly, which directly affects the operation of industrial entrained-flow gasifier and the service life of refractory bricks. In this study, the corrosion resistance of several typical coal slags for gasification on high chromia refractory bricks was comparatively investigated by static laboratory crucible tests and thermodynamic simulations. The results demonstrated that the corrosion degree of high chromia refractory bricks by different coal slags was high-Ca/Na slag > high-Fe slag > high-Si/Al slag. The surface structure of the refractory was relatively flat after corrosion by high-Si/Al slag, and the primary corrosion reaction was the partial dissolution of the matrix by the slag. High-Fe slag was prone to the precipitation of iron phases as well as the formation of (Mg, Fe) (Al, Cr)2O4 composite spinel layer at the slag/refractory interface. The high-Ca/Na slag was susceptible to react with the refractory to yield a low melting point phase, which led to the destruction of the matrix structure of the refractory and an isolated distribution of particles. In addition, the monoclinic ZrO2 in the refractory reacted with CaO in the slag to formed calcium zirconate, which loosened its phase toughening effect, was the primary factor that aggravated the refractory corrosion.

Dissolution behavior of spent MgO–C refractory in the CaO–SiO2–FeO slag system as a steelmaking flux

A large amount of spent MgO–C refractory is generated in steel plant every year. Because of the similarities in chemical and mineralogical composition of slag formers and MgO–C refractory, it is possible to reuse the spent MgO–C refractory as a steelmaking flux. To achieve this goal, it should promote the dissolution of MgO–C refractory during slag forming. In this study, the effect of slag composition on the dissolution behavior of spent MgO–C refractory in the CaO–SiO2–FeO slag system and the dissolution kinetics were investigated. It showed that the dissolution rate of MgO–C refractory was controlled by surface chemical reaction. The dissolution of MgO–C refractory led to an increase in the MgO content in slag while the FeO content decreased because the graphite in refractory was oxidized by FeO. Increasing temperature significantly promoted the dissolution of MgO–C refractory. The MgO–C refractory was readily dissolved in the low-basicity slag. A higher FeO content in slag was beneficial for the oxidation of graphite in refractory, resulting in better dissolution. The dissolution thickness of MgO–C refractory could exceed 4.0 mm under these conditions and its dissolution supplied some MgO to slag.

Optimization of alkali metals discharge performance of blast furnace slag and its extreme value model

Abstract In order to improve the alkali metals discharge capacity of slag, the gas-slag balance method was used to carry out the slag alkali metals discharge experiments, the effect of slag composition on alkali metals discharge performance of slag was studied, some suggestions were put forward to optimize the alkali metals discharge performance of slag and the extreme value model was established. The results show that the alkali metals discharge ratio of slag decreased with the increase in the binary basicity and mass fraction of TiO2, and increased with the increase in the mass fraction of MgO, Al2O3 and MnO. The change in slag composition led to the change in the solubility of alkali metal oxides in liquid slag, decomposition of alkali metal silicates, structure of the slag in liquid state and viscosity of the slag, and then affected the alkali metals discharge performance of slag. The ability of slag to absorb alkali metals was certain under the condition of fixed composition. With the help of slag alkali metals discharge extreme value model, whether the current slag meets the needs of blast furnace alkali metals discharge could be evaluated. The alkali metals discharge capacity of slag could be improved by optimizing the alkali metals discharge performance of slag combined with experiments and actual production.

Effect of Slag Compositions on Change Behavior of Nitrogen in Molten Steel

The problem of nitrogen pickup in the smelting process of the electric arc furnace (EAF) has not been solved well. Using seven slag–steel equilibrium experiments and theoretical analysis, the relation of the foaming index and optical basicity with the nitrogen capacity of slag was clarified. Meanwhile, the effect of slag composition on the equilibrium distribution ratio of nitrogen and the mass transfer coefficient of nitrogen pickup was also studied. The results show that, with the increase in slag basicity, the nitrogen pickup amount, nitrogen pickup rate, and nitrogen equilibrium distribution ratio LN increase. Increasing the foaming index of slag and reducing its optical basicity will increase the nitrogen capacity of slag, which is conducive to hindering the nitrogen pickup of molten steel. The relationship between slag optical basicity and nitrogen capacity can be expressed as lgCN = −5.59lgΛ − 12.41. With the increase in the Al2O3 content of slag, the nitrogen pickup amount of molten steel decreases and the nitrogen pickup rate decreases. The test with MgO = 7.5% showed the highest nitrogen pickup rate and the highest nitrogen pickup mass transfer coefficient, which were 0.21 × 10−4%/min and 1.97 × 10−4 cm/s, respectively. The test with Al2O3 = 7.5% in slag showed the lowest nitrogen pickup rate and the lowest nitrogen pickup mass transfer coefficient, which were 0.08 × 10−4%/min and 1.35 × 10−4 cm/s, respectively.

Effect of slag composition on the distribution and separation behavior of arsenic between CaO-based slag and liquid copper

To determine the effects of slag basicity and oxygen potential on the distribution of arsenic (As) between slag and liquid copper, high-temperature experiments were conducted using a Kanthal-Super electric furnace. The thermodynamic driving force of As removal from liquid copper was found to increase as the slag basicity increased because the excess free energy of As2O3 decreased with increasing basic oxide content in the slag. The addition of a small amount of Na2O improved As removal efficiency from the liquid copper. In the case of acidic (i.e., low basicity) slag, the As was minimally distributed to slag phase due to the low activity of CaO in the slag. As a result, the basicity of slag should be carefully controlled for the efficient removal of As. In addition, As was segregated and stabilized in the (Mg,Fe)O monoxide as well as in crystalline phases (magnesium arsenate, Mg3(AsO4)2 and ferric arsenate, FeAsO4) formed due to the high contents of MgO and FeO in the slag, from which it was concluded that As enrichment and separation can be achieved during cooling process.

Influence of Na2O on the thermodynamics properties, viscosity, and structure of CaO–SiO2–MgO–Al2O3–BaO–Na2O slag

This article investigated the effect of Na2O on the viscosity and structure of CaO–SiO2–MgO–Al2O3–BaO–Na2O slag. To understand the stability of slag at high temperatures, the “excessive heat of slag” was calculated. The structure of slag was analyzed using Raman and 27Al magic angular spinning nuclear magnetic resonance (MAS-NMR) techniques. The results showed that the viscosity decreased with an increase in Na2O content in the range of 0 to 4 wt%, while the excessive heat of slag increased because the effect of slag composition on its heat capacity was more significant than that of temperature. From the perspective of heat supply, it should increase the fuel ratio of the blast furnace to ensure a stable furnace temperature when raising Na2O content. The mole fraction of Q Si0 (QSin, n is the number of bridging oxygen in a [SiO4]-tetrahedron) and Q Si2 increased gradually, whereas that of Q Si3 decreased obviously. The [SiO4]-tetrahedral structures were depolymerized, which reduced the number of bridging oxygen. Simultaneously, the increment in non-bridging oxygen caused the transformation from AlO4 to AlO5 and AlO6, thus decreasing the fraction of the network former (AlO4). The connection between [SiO4] and AlO5 or AlO6 weakened the strength of the network structure and increased the proportion of the Al–O bond.

Effect of Slag Composition on the Distribution and Separation Behavior of Arsenic between Cao-Based Slag and Liquid Copper

Effect of Slag Composition on the Distribution and Separation Behavior of Arsenic between Cao-Based Slag and Liquid Copper

Effects of slag composition and additive type on desulfurization of rejected electrolytic manganese metal scrap by Na2O-containing electroslag

Effects of slag composition and additive type on desulfurization of rejected electrolytic manganese metal scrap by Na2O-containing electroslag

Effect of Slag Composition on Dephosphorization and Foamability in the Electric Arc Furnace Steelmaking Process: Improvement of Plant Operation

Effect of Slag Composition on Dephosphorization and Foamability in the Electric Arc Furnace Steelmaking Process: Improvement of Plant Operation

Recycling of Steelmaking Slag in Seawater as an Iron Supplier: Effects of Slag Composition, Carbonation and Usage of Gluconic Acid

Recycling of Steelmaking Slag in Seawater as an Iron Supplier: Effects of Slag Composition, Carbonation and Usage of Gluconic Acid

Effect of slag composition on elements oxidation behavior of GH984G superalloy for electroslag remelting withdrawal process

Effect of slag composition on elements oxidation behavior of GH984G superalloy for electroslag remelting withdrawal process

Effects of Slag Composition and Impurities of Alloys on the Inclusion Transformation during Industrial Ladle Furnace Refining

The inclusion of the MgO·Al2O3 (MA) spinel and CaO–Al2O3 are occasionally observed during the refining of Al–killed steel, even without the intentional additions of Ca and Mg. Many studies have focused on the source of Mg and Ca; however, especially for the formation of CaO–Al2O3–type inclusions, some recent results showed that Ca was difficult to dissolve from refining slag, even when the Al content in molten steel was high. To confirm these differences, industrial experiments were designed in this study, and the effects of the FeO and MnO contents, as well as the impurities of the alloying materials, were discussed. The results showed that, when the FeO and MnO contents in slag were high (about 10 mass%) at the start of LF (ladle furnace), all inclusions remained as Al2O3, despite alloying. Using the slag with low FeO + MnO content (<1~2 mass%), the Al2O3 inclusions changed to the MA spinel, but CaO–Al2O3 inclusions were not observed, indicating that CaO–Al2O3 inclusions were difficult to form by the steel/slag reactions under the current conditions. Only for the molten steel that contained a low level of dissolved oxygen and a large amount of Fe–Si, which contained Ca as the impurity was added, CaO–Al2O3 inclusions were generated.

Effect of slag composition on desulfurization during recycling rejected electrolytic manganese metal by electroslag remelting

To reduce the Mn vaporization during recycling rejected electrolytic manganese metal by electroslag remelting, it is proposed to reduce the temperature of molten slag pool, but which leads to the degradation of slag desulfurization. The desulfurization by interaction between CaF2–CaO–Al2O3–Na2O slag and rejected electrolytic manganese metal scrap was studied from the view of thermodynamics in this study. The results show that sulfur distribution ratio decreases with increase of CaF2 content, and increases with the increase of Na2O content and temperature. Na2O increases sulfur distribution ratio of slag by increasing CaO activity. Na2O addition in CaF2–CaO–Al2O3–Na2O slag can enhance desulfurization ability of slag due to the larger sulfur distribution ratio and lower viscosity. Thus, sulfur content in test of slag T3 bearing 45.8 wt% CaF2-23.2 wt% CaO-22.7 wt% Al2O3-8.3 wt% Na2O is much lower than that of slag without Na2O, implying that 45.8 wt% CaF2-23.2 wt% CaO-22.7 wt% Al2O3-8.3 wt%Na2O slag is the promising slag for recycling rejected electrolytic manganese metal by ESR.

Distribution Behavior of Phosphorus in 2CaO·SiO2-3CaO·P2O5 Solid Solution Phase and Liquid Slag Phase

In this paper, the CaO-SiO2-FetO-P2O5 dephosphorization slag system during the premier and middle stage of the converter process was studied, the effect of slag composition on the distribution ratio and activity coefficient of P in the n·2CaO·SiO2-3CaO·P2O5 (recorded as nC2S-C3P) solid solution phase and liquid slag phase in the slag system was studied used by the high temperature experiment in laboratory, the theoretical calculation of thermodynamics, and the scanning electron microscope and the energy dispersive spectrometer (recorded as SEM/EDS). The research results show that when the FeO content in the liquid slag increases from 32.21% to 50.31%, the distribution ratio of phosphorus (recorded as LP) in the liquid slag phase increases by 3.34 times. When the binary basicity in the liquid slag increases from 1.08 to 1.64, the LP in the liquid slag phase decreases by 94.21%. In the initial slag, when the binary basicity increases from 2.0 to 3.5, the LP decreases by 70.07%. When FeO content increases from 38.00% to 51.92%, the LP increases by 6.15 times. When P2O5 content increases from 3.00% to 9.00%, the LP increased by 10.67 times. When the FeO content in the liquid slag increases from 32.21% to 50.31%, the activity coefficient of P2O5 in the liquid slag phase (recorded as γP2O5(L)) increases by 54.33 times. When the binary basicity in the liquid slag increases from 1.08 to 1.64, γP2O5(L) decreases by 99.38%. When the binary basicity increases from 2.0 to 3.5, the activity coefficient of P2O5 in the solid solution phase (recorded as γP2O5(SS)) in the solid solution phase decreases by 98.85%. When P2O5 content increases from 3.00% to 9.00%, γP2O5(SS) increases by 1.14 times. When the binary basicity decreases from 3.5 to 2.0, n decreases from 0.438 to 0.404. When the FeO content increases from 38.00% to 51.92%, n decreases from 0.477 to 0.319. When the P2O5 content increases from 3.00% to 9.00%, n decreases from 0.432 to 0.164. The decrease of binary basicity and the increase of FeO and P2O5 content in the initial slag can reduce the value of n and enrich more phosphorus in the solid solution phase. The results can not only provide a theoretical basis for industrial production, but also lay a theoretical foundation for finding more effective dephosphorization methods.

Effect of Slag Composition on the Deoxidation and Desulfurization of Inconel 718 Superalloy by ESR Type Slag Without Deoxidizer Addition

Effects of slag composition and alloy content as well as temperature on the deoxidation and desulfurization of Inconel 718 superalloy by CaF2-CaO-Al2O3-MgO-TiO2 ESR-type slag without the addition of a deoxidizer were systematically investigated by laboratory-scale experiments and the developed mass transfer model. The model predictions were verified through comparison with experimental results in a double-layer crucible. The results showed that the oxygen content decreased with an increase of CaO, MgO and CaF2 content in the slag at 1773 K, and CaO has a great influence on the deoxidation of Inconel 718 alloy compared with MgO and CaF2 in slag, which was responsible for the decrease in equilibrium content of sulfur in the Inconel 718 alloy. The total oxygen and sulfur content decreased from 33.2 and 20 ppm in master alloys to about 10 and 6 ppm in alloy ingots at 1773 K, respectively. Properly increasing the Al and Ti content only lowered the oxygen and sulfur content in the nickel-based alloy to a limited extent when satisfying the mechanical properties of the Inconel 718 alloy. The interfacial oxygen content increased with increasing temperature, giving rise to a decrease in the desulfurization ratio $$ \left( {{{[{\text{pct S}}]_{t = t} } \mathord{\left/ {\vphantom {{[{\text{pct S}}]_{t = t} } {[{\text{pct S}}]_{t = 0} }}} \right. \kern-0pt} {[{\text{pct S}}]_{t = 0} }}} \right) $$. These results show that the lower temperature favored desulfurization of the nickel-based alloy.

The effect of slag composition and curing duration on the chloride ingress resistance of slag-blended cements

This paper reports the influence of varying curing durations on the chloride ingress resistance of slag blends. Samples were prepared by combining two slags (S1 and S2) with CEM I 52·5R cement at 30% by weight of slag. Mortar samples were cured for either 7 or 28 d, before being exposed to a 3% sodium chloride solution. Samples were subjected to two chloride exposure conditions (either complete submersion or a cyclic 6 h wetting and drying cycle). Depths of free chloride penetration as well as total and water-soluble chloride contents were measured for the exposed samples. Samples cured for 28 d before exposure showed far better resistance to chloride ingress than those cured for 7 d. The cement–slag blend with S1, having an alumina content of 12·23%, performed better than the blend with S2 (alumina content of 7·77%), especially for samples cured for 7 d. This was attributed to the higher basicity of S1. However, when the samples were cured for 28 d, the difference between the performances of the slag blends became minimal. Despite this, the overall performance of the slag blends, which was compared against a CEM I 42·5R-type cement, was found to be better at both curing durations.