FactSage Software Research Articles

The effect of complex extra-furnace treatment of metal melts on the formation of non-metallic inclusions in large-sized ingots

Abstract The article presents the results of studying non-metallic inclusions (NI) after extra-furnace treatment of the 13Cr9Mo2Co1NiVNbNB steel melt to produce large-sized ingots. The objects of the study were laboratory samples melted in a semi-industrial induction furnace with the capacity of 20 tons (the first batch), and samples obtained after melting in an electric arc furnace with the capacity of 120 tons, followed by modification and double vacuuming (the second batch).
Previously, using the Fact Sage software, modeling of the NI formation processes was carried out. The data were obtained on the possible NI composition and amount in this steel.
Studying NIs (the composition, the contamination index, inclusion parameters) was carried out on an ASPEX Explorer electron microscope using the method of automatic X-ray spectral analysis of particles (Automatic Features Analysis, AFA). It was established that in the samples of the first batch, the main part of the NIs consisted of chromium- and manganese-containing oxides: chromium-manganese spinels (Cr-Mn-O and Mn-Cr-Si-O groups), which occupy more than 94% of the total area of the NIs. In the samples of the second batch, the main part of the Nis was represented by Cr-Mn-O; Al-Cr-O; Cr-Al-Mn-O systems.
It was shown that the average size of non-ferrous substances in the samples of the laboratory batch and in industrial samples after extra-furnace treatment differs slightly (5-12%), however, the contamination index in industrial samples after vacuum treatment and especially after modification and repeated vacuum treatment was reduced by more than 10 times. The results obtained allow recommending vacuum treatment and complex modification with calcium and boron as measures to prevent the formation of non-ferrous metals and to improve metallurgical quality when smelting large ingots using complex alloy steels.

Corrosion behavior of co-gasification slag of furfural residue and coal on alumina-silica refractories

Gasification of furfural residue with coal can realize its efficient and clean utilization. But the high alkali metal content in furfural slag is easy to cause the corrosion of gasifier refractory. Two gasification coals with different silica alumina ratio and a furfural residue were selected in the study. The effects of furfural residue additions on corrosion of silica brick, corundum brick, high alumina brick and mullite brick were investigated by using XRD, SEM-EDS and Factsage Software, and the corrosion mechanism was analyzed. With increasing furfural residue addition, the permeability of the slags to high-aluminium-bearing refractories first decreases and then increases, while the permeability on silica brick shows a slight decrease trend. Leucite (KAlSi2O6) with high-melting temperature is generated from the reaction of K2O and SiO2 in slag with Al2O3 in refractories after furfural residue is added, which hinders the infiltration of slag in refractories. Kaliophilite (KAlSiO4) of low-melting point is formed when K2O content increases, and this contributes to the infiltration of slag in refractories. The acid-base reaction between slag and silica brick is distinctly occurred, more slag reacts with SiO2 in the silicon brick, resulting in a decrease in the amount of slag infiltrating into the silicon brick as furfural residue is added. The corrosion of silica brick is mainly caused by the acid-base reaction, while the corrosion of three alumina based refractory bricks of corundum, mullite and high alumina brick is determined by slag infiltration. A linear correlation between the percolation rate and slag viscosity is established, the slag permeability increases with decreasing viscosity, resulting in stronger permeability for the high Si/Al ratio slag with lower viscosity.

Thermodynamic Investigation of Propagating Behavior in SHS for Equiatomic and Non-Equiatomic NiTi Alloys Using Factsage Software

Thermodynamic Investigation of Propagating Behavior in SHS for Equiatomic and Non-Equiatomic NiTi Alloys Using Factsage Software

Bridging Thermochemical Technology and Ecology: Research Progress on Utilization of Factsage Software for Environmental Applications

Factsage is a robust thermodynamic calculation software that enables simulation and computation of complex multi-component and multi-phase system reactions. It has a variety of application fields such as metallurgy, energy, and environmental domains. This article elucidates the key functionalities of Factsage’s diverse modules, including Equilib, Viscosity, EpH, Reaction, and Phase Diagram modules. Furthermore, it delineates the present usage and research progress of the software in the realms of air pollution, water pollution, and solid waste treatment. By predicting the thermodynamic properties of pollutants, their chemical reactions, and complex phase changes, Factsage provides a critical scientific foundation for environmental decision-making and optimization of waste treatment processes. It showed its greater contributions to environmental protection and sustainable development.

Silver recovery into lead bullion from a lead concentrate by direct reduction with Na2CO3 and SiC reagents

ABSTRACT Silver has been recovered in lead bullion from a lead concentrate throughout a direct reduction process. The lead concentrate was obtained from a plant that processes polymetallic minerals located in the central mining area of Mexico. The direct reduction process has been tested through mixtures of Na2CO3 and SiC that were put in contact with the lead concentrate at 1000 °C for 60 min to produce lead bullion containing silver and slag. The produced lead bullion containing silver and the slag after direct reduction trials showed that it is possible to recover about 90% of lead and 86.5% of silver into the lead bullion, leading to a low silver content in the slag phase (<0.2 wt.%). The slag was constituted mainly by sodium silicate compounds such as Na2SiO3, Na4SiO4, and Na2Si2O5, when 50 wt. % of Na2CO3 and 10 wt. % of SiC regarding the initial charge of the lead concentrate was used. The proposed process has been assisted thermodynamically by the software FactSage 7.6, which allowed us to predict the main expected compounds and understand the process mechanism for silver recovery into a lead bullion using Na2CO3 and SiC reagents.

Thermodynamic modelling on the reaction between steel and slag

An integrated thermodynamic model was developed to determine the equilibrium between the slag and the steel at high temperatures, employing the Unified Interaction Parameter Formalism (UIPF) and the Associate Model (AM) for a twelve-element molten steel system (Fe–Al–C–Ca–Cr–Mg–Mn–N–O–S–Si–Ti). A model for slag activity was based on the Ion and Molecular Coexistence Theory (IMCT) and applied to a refining slag system (CaO–MgO–FeO–MnO–CaF2–SiO2–Al2O3–Fe2O3). Comparative analyses were conducted using FactSage software and experimental data, validating the accuracy of the established model. The impact of slag modifiers, specifically aluminum granules, on slag oxidability, and the role of CaO/Al2O3 ratio in slag desulfurization were investigated. The effect of slag modifier on the oxidability and the influence of CaO/Al2O3 on the desulfurization of the slag were determined using the current model. Aluminum in the slag modifier reacted with MnO and FeO in the slag, thereby reducing the oxidability of the slag. With a 30 wt% slag modifier, the MnO content in the slag (initially 15 wt%) stabilized and showed minimal change, dropping below 1 wt%. An increase in CaO content above 80 wt% in the slag led to a reduction of equilibrium sulfur in the steel to below 10 ppm. Little amount of calcium transferred from the slag into the steel with the increase in CaO content, but the [Ca] content remained below 0.5 ppm even though the content of CaO in the slag was greater than 80 wt%. The developed model offered a versatile tool for designing slag compositions tailored to various purposes.

Prediction of Coal Ash Flow Temperature Based on Gray Relational Analysis, Support Vector Regression and Genetic Algorithm.

Coal ash flow temperature significantly influences the operating conditions of entrained flow bed gasification. The relationship between the flow temperature of coal ash and its chemical composition remains uncertain despite being determined by it. To construct a reliable and accurate predictive method, machine learning models were used, and different support vector regression models were built to predict the flow temperature. The prediction results of the proposed gray relational analysis-genetic algorithm-support vector regression model can achieve high accuracy, with a root-mean-square error of 28.37, mean absolute error of 19.48K, and average deviation of 1.58%. Moreover, the prediction results of the proposed model are more accurate and efficient than those calculated by FactSage software, with a mean absolute error of 93.73K. This demonstrates the viability of applying the proposed machine learning model to predict the flow temperature of coal ash and its promising potential application in the area of coal chemical engineering.

A novel vacuum roasting technology applied to the processing of mineral medicine pyritum: low heavy metal and environmentally friendly

Pyritum, a mineral medicine, has been widely used in orthopedics and traumatology in China for nearly 1500 years. Before its use as a drug, it must be air-roasted and vinegar-quenched to produce an effective compound, pyrrhotite (Fe7S8), while reducing harmful substances. However, this process is prone to generating toxic compounds such as sulfur dioxide (SO2) and arsenic trioxide (As2O3). Moreover, processed pyritum sold in China still exhibits significant issues with high levels of arsenic (As) and lead (Pb). This study proposes a green processing method for vacuum roasting pyritum. FactSage software was used to confirm that the vacuum environment facilitates the production of Fe7S8 while effectively preventing oxidation and simplifying the removal of As and Pb. The iron (Fe) content within the temperature range of 600–1000 °C increases from 27.96% to 62.41%. X-Ray Diffraction (XRD) and Mineral Liberation Analyzer (MLA) results indicate a significant transformation of the primary component, pyrite (FeS2), in pyritum into Fe7S8.The optimal processing conditions were determined to be vacuum roasting at 1000 °C for 60 min, resulting in a remarkable removal efficiency of 70.27% for Pb and the complete elimination of As. It can be concluded that vacuum roasting pyritum is a simple, high-stability, environmentally friendly, and clean procedure.

Optimalisasi Pengendalian Rasio ICP Boat dengan Limbah Brick Ladle Converter Matte (Al2O3-SiO2) Menggunakan Simulasi Factsage

The purification process to increase the nickel content is carried out in a Pierce Smith converter through several stages, including charging, blowing, skimming, dry up, and casting, resulting in a nickel matte with a 75-78% nickel content. After casting, the nickel matte is stored in ladles, with each converter being able to accommodate the casting of 7 ladles, each with a capacity of about 15.5 tons. These ladles are made of carbon steel with a brick lining, consisting of castables on the walls and alumina brick on the bottom. Repeated pouring of matte into the ladles can cause surface erosion due to high heat input and matte friction, as well as chemical issues such as build-up. The refractory material in these ladles will undergo a total relining scheme, resulting in waste brick classified as B3 waste. The potential of the waste brick in the ladles is still quite high in producing residual nickel matte in a homogenized form. Therefore, the waste brick from the ladles will be considered to be mixed with ICP Boat with specific composition and distribution. The resulting mixture will be used as feed in the converter purification process by reviewing the variation of the waste brick to ICP Boat ratio using FactSage software simulation and validating the results through field experiments. FactSage software simulation recommends an improvement in the waste brick to ICP Boat mixture ratio of about 4.6-12% at a temperature of 1200°C to prevent the formation of spinel and olivine Keywords: Converter, ladle, brick, ICP boat, FactSage

Application of an Artificial Neural Network for Efficient Computation of Chemical Activities within an EAF Process Model

The electric arc furnace (EAF) is considered the second most important process for the production of crude steel and is usually used for the melting of scrap. With the current emphasis on defossilization, its share in global steelmaking is likely to further increase. Due to the large production quantities, minor improvements to the EAF process can still accumulate into a significant reduction in overall energy and resource consumption. A major aspect in the efficient operation of the EAF is achieving beneficial slag properties, as the slag influences the composition of the steel and can reduce energy losses as well as the maintenance cost. In order to investigate the EAF operation, a dynamic process model is applied. Within the model, the chemical reactions of the metal–slag system are calculated based on the activities of the involved species. In this regard, multiple models for the calculation of the chemical activities have been implemented. However, depending on the chosen model, the computation of the slag activities can be computationally demanding. For this reason, the application of a neural network for the calculation of the chemical activities within the slag is investigated. The performance of the neural network is then compared to the results of the previously applied models by using the commercial software FactSage as a reference. The validation shows that the surrogate model achieves great accuracy while keeping the computation demand low.

Formation mechanism and control of a kind of pit-shaped defect in Cf53 rolled products

Aiming at the frequent issue of pit-shaped surface defects in S-bearing and Al-killed steel products and the related poor castability due to submerged entry nozzle (SEN) clogging, the melting and casting process of a popular auto steel Cf53 has been studied based on in-situ investigation and experimental analysis. To clarify the generation of the pit-shaped defects, the local surface chemistry, evolution of steel inclusions throughout the melting process, SEN clogging substances, and the internal relationship among them were systematically analyzed. The results show that this type of defect in the Cf53 rolled products is caused by the large-sized composite inclusions rich in CaS, which originate from the molten steel during the refining process, gradually accumulate on the inner wall of the SEN during casting, and finally lead to SEN clogging. The loose structure of clogging inclusions makes them prone to fall off into the mold and get trapped by solidifying steel shell. The formation mechanism of the inclusions was studied through FactSage software calculation. The results show that the increase in total sulfur and total calcium content, and the decrease in total oxygen content and temperature in steel will lead to CaS inclusion formation, which agrees reasonably well with experimental results. An optimized refining process to reduce calcium addition into molten steel is proposed accordingly, which achieves a remarkably alleviation in casting SEN clogging and an elimination of the pit-shaped defects on the final rolled products as well.

The Effect of Composition and Temperature on the Hydrogen Reduction Behavior of Sintered Pellets of Bauxite Residue-Lime Mixtures

This study explores the isothermal hydrogen reduction of sintered pellets made of a mixture of bauxite residue and calcite with varying compositions at different reduction temperatures. Sintered pellets with varying compositions show three primary iron-containing oxide phases including brownmillerite, srebrodolskite, and fayalite; however, brownmillerite is the major phase in all the sintered pellets. The sintered pellets were reduced in a thermogravimetry furnace to establish instantaneous weight reduction with respect to time. Phases and microstructural analysis were carried out using X-ray diffraction and scanning electron microscopy, respectively. Mercury intrusion porosimeter and pycnometer were utilized to assess the porosity and density of the reduced pellets. Thermochemistry calculations were performed using the thermodynamics software FactSage 8.2. The reduction rate is most pronounced at a temperature of 1000 °C for all pellet compositions. It is intriguing to note that the rate of reduction shows minimal variance across pellets with different compositions; however, the higher calcite pellets exhibit a higher initial rate of reduction. Various kinetic models were examined to determine the activation energies for three different composition pellets, and the three-dimensional diffusion model has been well suited for this process. Close activation energies in the range of 84.6 to 94.8 kJ were obtained. A slightly higher activation energy was obtained for lower CaCO3 added pellets, and it was attributed to their reduced porosity and increased sintering, impeding the reaction kinetics. There were no significant differences in the formation of mayenite with varying the calcite amount; however, higher calcite pellets indicated more mayenite formation.Graphical

OPTIMIZING VANADIUM CONVERTER SLAG UTILIZATION: TARGETED ENRICHMENT AND STABILIZATION OF VANADIUM THROUGH NON-EQUILIBRIUM SOLIDIFICATION

The objective of this research was to optimize the comprehensive utilization of vanadium converter slag through targeted enrichment and stabilization of heavy metal vanadium. Employing the non-equilibrium solidification theory and FactSage software, we investigated the potential of modifying vanadium converter slag. When the original slag failed to generate vanadium-rich spinel with usable V elements, introducing modifying agents Fe and Al proved effective. Fe facilitated the enrichment of Cr within spinel, while Al significantly promoted the V enrichment. Expanding on this, we systematically examined the influence of Fe2O3, Al2O3 and MgO contents on spinel phase precipitation during vanadium slag solidification. The addition of Al resulted in the precipitation of corundum, hematite, spinel, olivine and diopside phases. With an increase in the Fe2O3 content, the precipitation of FeV2O4 and MgV2O4 initially increased, peaking at 9.67 % before subsequently decreasing. Maintaining the Fe2O3 content within a range of 25–30 % proved optimal for enhancing vanadium precipitation and enrichment. In contrast, variations in the Al2O3 content had minor impacts on SP-V phase precipitation, with slight effects on FeV2O4 reaching 10.34 %. Furthermore, the incorporation of MgO facilitated the precipitation of MgV2O4 while concurrently suppressing the FeV2O4 precipitation. By judiciously controlling the MgO content at approximately 20 %, vanadium enrichment in the form of FeV2O4 and MgV2O4 spinel phases reached a remarkable 94.46 %.

Si3N4 preparation from photovoltaic kerf loss silicon waste by copper collaborative nitriding method

In this work, Si3N4 powders were prepared by collaborative direct nitriding method from photovoltaic kerf loss silicon waste. The catalytic effect of copper (Cu) on the direct nitriding reaction of photovoltaic Si waste and the morphologies of the nitriding products were investigated. The quantitative analysis of XRD results and thermogravimetric results demonstrate that Cu significantly reduces the initial nitriding temperature, and Cu has a positive effect on the nitriding of silicon waste. At 1300 °C, the sample without Cu had almost no nitriding reaction, while the total conversion rate of kerf loss waste Si was 100 %, and the yield of (α+β) Si3N4 was up to 79.2 % with 8 wt% Cu additive. The thermodynamic analysis of the Si-O-N-Cu and nitriding process was carried out by FactSage software. Moreover, the morphologies of the nitride products were observed by SEM. The addition of copper promoted the generation of Si3N4 nanorods, and the number and diameter of α-Si3N4 nanorods increased with the increase in copper content. Three reaction mechanisms of Si nitridation were discussed. This work provides a feasible method to reuse and recycle the kerf lost silicon waste.

Investigation on ash fusion characteristics and mineral transformation mechanism of sorghum straw by paper-making sludge addition

The co-combustion of sorghum straw and paper-making sludge (PMS) is beneficial to alleviate the ash-related problem in sorghum straw combustion process. In this paper, the mineral migration and transformation behavior in sorghum straw ashes with the addition of PMS ashes under an oxidizing atmosphere were investigated using an X-ray diffractometer, thermogravimetric-derivative thermogravimetric, scanning electron microscopy-energy dispersive X-ray detector, and FactSage software. The results demonstrated that the increase in the PMS ash mass ratio led to an increase in ash fusion temperature (AFT) of sorghum straw mixtures. The generations of high melting-point (MP) calcium feldspar (e.g., Ca2MgSi2O7, Ca2Al2SiO7, Ca3MgSi2O8, and Ca7Mg (SiO4)4) and phosphates (e.g., Ca3P2O8, Ca5P2SiO12, and Ca7P2Si2O16) caused the increases in the AFT. The maximum weight loss of sorghum straw ashes decreased with the increasing PMS ash mass ratio, and the surface of the ashes underwent the transition from smooth to a whole loose and rough, which alleviated the ash-related problems of sorghum straw. The addition of PMS ashes decreasing the liquid-phase content calculated by FactSage at the same temperature also explained the sorghum straw AFT increase. The changes of AFT and its corresponding mechanisms in the sorghum straw with PMS ash addition under an oxidizing atmosphere provided the support for large-scale combustion of biomass.

Oxide Reduction Treatment with a Thermal Plasma Torch: A Case Study

This article presents the findings of a study on oxide reduction utilizing a novel reducing plasma torch, employing greenhouse gases such as CO2 and CH4 as plasma gases. The primary aim of this investigation is to establish the viability of this approach. The innovative plasma torch was employed to reduce various oxides, including aluminum oxide, iron oxide, and titanium oxide, as well as a mixed oxide composition, employing a CO2/CH4 molar ratio of 1:1 within a spouted bed reactor. Following plasma treatment, X-ray diffraction (XRD) analysis was conducted to examine the metallic phases, notably titanium, iron, and aluminum. SEM–EDS observations were carried out to assess microstructural changes and identify elemental compositions pre- and post-plasma treatment. The results demonstrate that within the conical section of the reactor, titanium oxide experiences partial reduction, resulting in limited titanium production, while aluminum oxide and iron oxides (magnetite and hematite) undergo reduction to yield aluminum and iron, respectively. Thermodynamic calculations, performed using Factsage software version 8.3, were utilized to predict stable-phase formations following plasma treatment for each material.

Development and application of matte/speiss/metal thermodynamic database for optimization of processing of drosses, dusts and reverts from lead, zinc and copper production

Detrimental elements such as arsenic and antimony tend to accumulate in dusts and drosses of lead-zinc as well as copper smelters. These by-products are commonly treated in dedicated reductive smelting units producing Cu-rich matte, As-Sb-collecting speiss and Pb-rich metal, as well as liquid slag. Such process would have a complex distribution of elements (Cu, Fe, Pb, Zn, Ni, Sn, Sb, As, Ag, Au, S, etc.) among four liquid phases. Thermodynamic calculations can be used for predictions and optimization of such processes. They must rely on accurate models developed in integration with experimental program. Present study reports results of recent progress in experimental and modelling studies of As, Sb-containing speiss systems and demonstration of calculations relevant for industrial conditions. Experimental methodology consisted of equilibration, quenching and electron probe X-ray microanalysis. Calculations were performed using FactSage software and thermodynamic database developed based on the dedicated recent experiments. The main findings of the paper are: a set of binary and ternary diagrams relevant to matte and speiss formation conditions; distribution of Ag and Au among liquid Pb and speiss in key quaternary systems; and distributions of 10 main elements for industrially relevant matte/speiss/metal multicomponent equilibria.

Study on the Cleanliness of SWRS82B Hard Wire Steel Refined by Fluorine‐Free Slag with Medium and High Basicity

In order to apply and develop fluorine‐free slag in steelmaking, it is of great significance to study the effect of composition for fluorine‐free refining slag on the cleanliness of molten steel which affects its performance directly. The effect of composition of fluorine‐free refining slag with medium and high basicity on the contents of impurity elements for sulfur and oxygen, and characteristics of inclusions in SWRS82B hard wire steel, are investigated systematically. Sulfide capacity of refining slag is estimated based on the Royal Swedish Institute of Technology model. Dissolved oxygen content in molten steel equilibrated by refining slag is calculated based on Factsage software and classical thermodynamics. The calculated results are in good agreement with experimental results. The plasticity of inclusions at high temperature and low temperature is analyzed by phase diagram and Young's modulus calculation. The best cleanliness and inclusions of SWRS82B steel are obtained with slag composition of 53%CaO–19%SiO2–19%Al2O3–7%MgO, which has good melting characteristics. The impurity elements sulfur and oxygen in steel can be controlled for 26 and 19 ppm, respectively, and the average size of inclusions is 2.84 μm.

Ash melting behaviors of high-sodium coal and its co-combustion with coal gangue to inhibit slagging

Fouling and slagging are major challenges that impede the clean and efficient use of high-sodium coals (HC) for power generation. To address these persistent issues, this study examined the impact of sodium (Na) on ash-melting behaviors and assessed the feasibility of mitigating fouling and slagging through the co-combustion of HC with coal gangue (CG). The mineral transformation mechanisms were analyzed through experimental and thermodynamic calculations using the FactSage software. The potential for inhibiting slagging through the co-firing of HC with CG rich in silica (SiO2) and alumina (Al2O3) was also investigated. The presence of Na-containing species led to the formation of more flexible minerals and lowered the ash fusion temperatures (AFTs). Na not only decreased the initial temperature required for the formation of the liquid phase but also increased the proportion of the liquid phase during high-temperature ash-melting processes. Co-firing with CG rich in silica and alumina significantly improved the AFTs of HC. Furthermore, this approach effectively reduced the propensity for fouling and slagging. In practice, it is recommended to control the co-firing ratios of CG within 10–30% to inhibit slagging and fouling issues while maintaining a smooth boiler operation.

The Direct Alloying of Steel through Silicothermic Self-Reduction of Chromite Ore Utilizing Si-Containing Solid Waste

Organosilicon materials generate copious amounts of Si-containing solid waste during production, leading to severe environmental pollution and substantial resource squandering. In pursuit of the resource utilization of Si-containing solid waste, this study conducted experimental research on the direct alloying of molten steel through the silicothermic self-reduction of chromite ore using Si-containing solid waste as a reducing agent. Additionally, thermodynamic analysis was performed, employing the thermodynamic calculation software FactSage 8.2 (Thermfact Ltd., Montreal, QC, Canada and GTT-Technologies, Aachen, Germany), to examine the equilibrium reactions of the silicothermic reduction of chromite ore and the variations in the thermodynamic equilibrium compositions of slag and metal phases. The results indicate a reduction sequence for the reducible components in chromite ore as Fe2O3 → Cr2O3. The introduction of CaO and Al2O3 into the silicothermic self-reduction compacts altered the forms of Fe and Cr oxides in equilibrium, significantly reducing the standard Gibbs free energy (ΔG0) of the silicothermic reduction reaction. The initial slag melting point decreased from 1700 °C without the addition of CaO and Al2O3 to 1500 °C with the addition of CaO and Al2O3. Correspondingly, the slag viscosity at 1600 °C decreased from 134.1 Pa·s without CaO and Al2O3 addition to 1.81 Pa·s with CaO and Al2O3 addition. The addition of CaO and Al2O3 accelerated the reduction of Cr oxide in chromite ore and enhanced the recovery of Cr, consistent with the thermodynamic calculation results. In the process of steelmaking through the direct alloying of chromite ore silicothermic self-reduction compacts, the final recovery rate of Cr increased from 86.4% without CaO and Al2O3 addition to 95.4% with CaO and Al2O3 addition.