Search Results (161)

A previously pyrometallurgical process, developed to obtain a Pb-Ag alloy and a slag rich in sulfur from the recycling of a mixture of industrial wastes of jarosite and lead paste, was thermodynamically assessed at 1200 °C. The industrial jarosite sourced from a Mexican zinc hydrometallurgical plant corresponded to an ammonium jarosite with a measurable silver content. The specific heat capacity (Cp) of the ammonium jarosite was obtained from TGA and DSC measurements, as well as the thermodynamic functions of enthalpy, entropy, and Gibbs free energy. The Cp was successfully modeled using polynomial regression, with a second-degree polynomial employed to describe the low-temperature behavior. The thermodynamic data generated were input into the thermodynamic software FactSage 8.2 for modeling of the lead paste–ammonium jarosite-Na₂CO₃-SiC system and represented by stability phase diagrams. The thermodynamic assessment of the pyrometallurgical process predicted compounds formed at high temperatures, showing that a Pb-Ag alloy and a slag rich in Na, S, and Fe (NaFeS₂ and NaFeO₂) were obtained. The compounds formed evidence of the effective sulfur retention in the slag, which is crucial for mitigating SO₂ emissions during high-temperature treatments. The experimental compounds, after solidification, were determined by X-ray diffraction measurements to be Na₂Fe(SO₄)₂ and Na₂(SO₄), which reasonably match the thermodynamic assessment. The heat capacity of the ammonium jarosite provides essential thermodynamic insights into the compositional complexities of industrial waste, which are particularly relevant for thermodynamic modeling and process optimization in pyrometallurgical systems aimed at metal recovery and residue valorization. Full article

With the rapid development of renewable energy, the co-combustion of Zhundong coal and biomass has attracted more and more attention. However, the high content of alkali metals in Zhundong coal and biomass leads to serious slagging and fouling in the co-combustion process. In this study, cotton straw was selected for co-combustion with Zhundong coal. The ash deposition model was established according to the melting ration calculated by Factsage, and the ash deposition characteristics during the co-combustion of Zhundong coal and cotton stalks in the actual boiler were explored by Fluent. The results showed that the K₂O content in ash increased from 0.31% to 9.31% with the increase in the blending ratio, while the contents of other components had no significant changes. In addition, with the increase in the blending ratio, the ash deposition rate increased from 0.00327 kg/(m²·s) to 0.00581 kg/(m²·s), an increase of 77.6%. The reduction in the tangential circle diameter obviously alleviated the ash deposition on the wall. When the tangential circle diameter was reduced to 400 mm, the ash deposition rate was 0.00207 kg/(m²·s), which was 37.6% lower than the original condition. Full article

Thermal Energy Storage (TES) technologies improve solar power dispatchability by addressing the important challenge of energy intermittency. Sensible heat energy storage technology using materials based on Ordinary Portland Cement (OPC) is the simplest and most economical. However, the operation of these materials is limited to temperatures below 400 °C due to the structural degradation of OPC at this temperature. This paper investigates the design and development of inorganic polymers based on Construction and Demolition Waste (CDW) as a sustainable, low-cost, and environmentally friendly alternative to OPC-based materials for high-temperature sensible TES applications. Based on the ternary systems Na₂O-SiO₂-Al₂O₃ and K₂O-SiO₂-Al₂O₃, representative compositions of CDW-based inorganic polymers were theoretically designed and evaluated using the thermochemical software FactSage 7.0. The experimental verification of the theoretically designed inorganic polymers confirmed that they can withstand temperatures higher than 500 and up to 700 °C. The optimized materials developed compressive strength around 20 MPa, which was improved with temperatures up to 500 °C and then decreased. Moreover, they presented thermal capacities from 600 to 1090 J kg⁻¹ °C ⁻¹, thermal diffusivity in the range of 4.7–5.6 × 10⁻⁷ m² s⁻¹, and thermal conductivity from 0.6 to 1 W m⁻¹ °C⁻¹. These properties render the developed inorganic polymers significant candidates for TES applications. Full article

Alkali metals in fuel seriously affect the normal operation of generator sets. Using agricultural waste (AW) from a corn field as raw material, the dynamic change of alkali metal K migration and transformation and the effect of competition between chlorine and sulfur on the behavior of AW were studied systematically. The results showed that transformation between different forms of K, especially water-soluble K, occurred. At low temperatures, K remained in the ash in the form of inorganic salt, and high temperature precipitated K and formed insoluble alkali metal compounds. Via FactSage thermodynamic equilibrium calculations, it was confirmed that KCl reacted with SiO₂ to form a K₂O·nSiO₂ molten mixture in combustion. K initially existed in the form of KCl (s) and K₂SO₄ (s), high temperature promoted its transformation and decomposition, and it was eventually released as KCl (g). During combustion, Cl was more volatile than K, while S reduced the release of K and Cl through sulfation reaction to reduce the sediment viscosity. Full article

Rapid progress in lithium-ion batteries and AI-powered autonomous driving is poised to propel electric vehicles to a 50% share of the global automotive market by the year 2035. Today, there is a major focus on recycling electric vehicle motors, particularly on extracting rare earth elements (REEs) from NdFeB permanent magnets (PMs). This research is based on a single-furnace process concept designed to separate metal components within PM motors by exploiting the varying melting points of the constituent materials, simultaneously extracting REEs present within the PMs and transferring them into the slag phase. Thermodynamic modeling, via Factsage Equilib stream calculations, optimized the experimental process. Simulated materials substituted the PM motor, which optimized modeling-directed melting within an induction furnace. The 2FeO·SiO₂ fayalite flux can oxidize rare earth elements, resulting in slag. The neodymium oxidation reaction by fayalite exhibits a ΔG° of −427 kJ when subjected to an oxygen partial pressure ($P_{O_2}$) of 1.8 × 10⁻⁹, which is lower than that required for FeO decomposition. Concerning the FeO–SiO₂ system, neodymium, in Nd³⁺, exhibits a strong bonding with the ${\mathrm{S}\mathrm{i}\mathrm{O}}_4^{4^{-}}$ matrix, leading to its incorporation within the slag as the silicate compound, Nd₂Si₂O₇. When 30 wt.% fayalite flux was added, the resulting experiment yielded a neodymium extraction degree of 91%, showcasing the effectiveness of this fluxing agent in the extraction process. Full article

Treating bauxite residue as an alternative source of metals for iron and aluminum industry is an approach to promote circular economy in metal industries. Reduction of metal oxides with a H₂-based process is an important step for the decarbonization of metal industry. In this study, bauxite residue (BR) pellets were prepared and were reduced with different H₂-H₂O gas compositions at different temperatures, which yielded with various degrees of reduction. The bauxite residue pellets were made from a mixture of bauxite residue and Ca(OH)₂ powders and sintered at 1150 °C. Hydrogen reduction was carried out on the oxide pellets using a resistance furnace at elevated temperatures in controlled reduction atmosphere of H₂-H₂O gas mixtures, which resulted in the reduction of iron oxides in the pellets. Unreduced and reduced pellets were subsequently heated to 1400 °C to study their sintering behavior during H₂ reduction using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) techniques to investigate the evolution of phases related to slag formation. Equilibrium module of Factsage™ was utilized to analyze results of thermal analysis. Both chemical and physical changes that occurred during the sintering process of the H₂-reduced BR pellets were successfully detected by TG–DTA analysis, and the initial slag- and gas-phase formation were detected to occur from 900 °C and 1180 °C, respectively. One of the most notable chemical reactions to occur during the analysis was formation of mayenite at 810 °C, which is easily leachable, providing potential for recovery of alumina. Full article

Zeolite Battery Research Africa (ZEBRA) batteries (Na-NiCl₂ solid electrolyte batteries, SEBs) have commercial applications in energy storage due to their low costs and recyclability, long lifetime, and high safety. In commercial ZEBRA batteries, Ni electrode and beta’’-alumina solid electrolyte (BASE) have a more than 70% share of the overall cell material costs. Na-ZnCl₂ all-liquid batteries (ALBs), which replace Ni with abundant and low-cost Zn and BASE electrolyte with molten salt electrolyte, could reduce costs and provide a longer lifetime and higher safety, making their application in grid storage promising. However, compared to SEBs, ALBs are in an early development stage, particularly for their molten salt electrolytes, which have a significant effect on the battery performance. Physical and chemical properties of the salt electrolyte like melting temperatures and solubilities of electrode materials (i.e., Na and Zn metal) are vital for the molten salt electrolyte selection and battery cell design and optimization. In this work, the binary and ternary phase diagrams of salt mixtures containing NaCl, CaCl₂, BaCl₂, SrCl₂, and KCl, obtained via FactSage simulation and DSC measurements, as well as the solubilities of electrode materials (Na and Zn metals), are presented and used for the selection of the molten salt electrolyte. Moreover, various criteria, considered for the selection of the molten salt electrolyte, include high electromotive force (EMF) for suitable electrochemical properties, low melting temperature for large charge/discharge range, low solubilities of electrode materials for low self-discharge, low material costs, and high material abundance for easy scale-up. Based on these criteria, the NaCl-CaCl₂-BaCl₂ and NaCl-SrCl₂-KCl salt mixtures are selected as the two most promising ALB molten salt electrolytes and suggested to be tested in the ALB demonstrators currently under development. Full article

The thermodynamic equilibrium of the gas-phase system in lead smelting flue gas was studied using FactSage 8.2 software, and the effects of temperature, the main components of the gas phase, and other factors on the SO₃ content in the equilibrated flue gas were investigated. In addition, experimental research was conducted on a solid-phase catalysis experimental platform to investigate the effect of lead smelting ash on SO₂ catalytic oxidation. The results show that temperature and initial O₂ content in flue gas have a significant impact on the equilibrium concentration of SO₃, while the initial SO₂ content in flue gas has a relatively small impact on the equilibrium concentration of SO₃; the fly ash from the lead smelting flue promotes the conversion of SO₂ to SO₃ in the flue gas. SO₃-suppression experiments show that PbS can adequately inhibit SO₃ formation in a simulated flue gas environment, and the content of SO₃ after adding PbS under different oxygen contents and SO₂ atmospheres does not exceed 0.6%. Through the method of thermodynamic simulation and experimental verification, this study reveals the catalytic oxidation mechanism of SO₂ in lead dust and proposes the use of PbS as an in situ SO₃ inhibitor. Full article

The purity of a steel is an important factor influencing the quality of the final products. Therefore, it is important to optimize the existing and develop new steelmaking technologies that affect the resulting purity. Electro slag remelting is a technology of tertiary metallurgy, which can advantageously be used to fabricate high quality steels. The study presents selected theoretical aspects of oxide systems and their specific influences on effectiveness of the electro slag remelting technology. The aim of this work was to experimentally analyze the purity of a tool steel fabricated by electro slag remelting using two different oxide systems (fused slags). The core of the study is the determination of the overall presence of elements in the steels, a thorough investigation of the presence of (not only) oxide-based inclusions within the investigated tool steel, and a detailed analysis of their chemical composition, including the size of these non-metallic inclusions, using energy dispersive X-ray (EDX) on the scanning electron microscope (SEM). Last but not least, the determination of the modification of the occurring non-metallic inclusions and verification of the experimentally acquired results as well as the calculation of the liquid and solid temperature and the calculation of the viscosity of the slags using the FactSage calculation software was performed. The results showed that the used slag influenced especially the occurrence of Mg and Al-based oxide inclusions. The CaS-type inclusions were present within all of the examined samples. The slag type influenced not only the typical morphology and size of the inclusions (especially of the CaS type), but also the tendency of the steel to exhibit localized corrosion when exposed to the ambient environment. This research can contribute to a better understanding of the effect of oxidation systems on the resulting purity and properties of ESR steels, thereby advancing the production of tool steels with higher quality and performance requirements. Full article

Thermodynamic calculations were carried out on typical tungsten cathode materials using Factsage software within a temperature range of 1000–3400 °C. The relationship between the phase stability and electron emission performance of the cathode in a vacuum environment and under a protective atmosphere was investigated. The thermodynamic stability of tungsten cathodes doped with different proportions of carbides and oxides was calculated. It was found that when the doped phase (ThO₂, La₂O₃, Y₂O₃, Lu₂O₃, Er₂O₃, Gd₂O₃, TiO₂, ZrO₂, HfO₂, ThC₂, LaC₂, YC₂, TiC, ZrC, and HfC) in the cathode starts to be consumed, the electron emission performance of the cathode will decline. Therefore, the high-temperature stability of the doped phase carbides and oxides also affects the operating temperature of the cathode. To verify these results, this study tested the electron emission performance of W–La₂O₃, W–ThO₂, W–ZrO₂, W–ZrC, and W–HfC, plotting their volt–ampere characteristic curves. The results indicated that the W-La₂O₃ cathode exhibits the best emission performance at low temperatures, while the W-ThO₂, W–ZrO₂, W–ZrC, and W–HfC cathodes showed better emission performance at high temperatures. The experimental results are in good agreement with the simulation results. The thermal stability of the doped phase is closely related to the high-temperature thermal stability of the cathode. Full article

The BOF steelmaking process involves complex physical and chemical reactions, making precise control challenging when relying solely on human experience. Therefore, understanding the reaction mechanisms and developing simulation models for the BOF process are crucial for enhancing control accuracy and advancing intelligent steelmaking. In this study, the physical and chemical behaviors in various reaction zones were first analyzed under actual production conditions using the multi-zone reaction theory. Then, a comprehensive mechanism model for BOF steelmaking was established, and an integrated simulation of metallurgical reactions during the BOF steelmaking process was performed using FactSage thermodynamic software. Finally, the validity of this comprehensive model was verified through actual production data. The results show that the relative deviation of the cumulative decarburization rate ranges from −0.66% to 1.68%, while the absolute deviation of the calculated carbon content curve compared to the actual curve is less than 0.12%. This research helps clarify the variation patterns of key process parameters in BOF steelmaking, playing a significant role in advancing the intelligence of the BOF steelmaking process. Full article

In view of the high loss of iron during hot metal desulfurization treatment at Pangang Steel, the factors influencing slag skimming iron loss were analyzed thoroughly by thermodynamic calculation with the aid of FactSage. A desulfurization modifier containing Na₂O and Al₂O₃ was designed. An industrial verification test was conducted for the newly designed calcium-based agent. The test results indicate that adding 8% of the modifier to the passivating lime achieves the optimal modification effect on the desulfurization slag. After modifying the desulfurization slag, the consumption of magnesium powder for every 0.001% sulfur removed decreased from 0.0149 kg to 0.0136 kg, the iron loss during slag skimming reduced from 3.52% to 2.28%, and the average slag skimming time shortened by 1.5 min. These improvements significantly lowered production costs, enhanced desulfurization efficiency, and laid the foundation for the widespread application of the semi-steel silicon addition process. Full article

Saprolite ores in nickel laterite deposits are pyrometallurgically processed to produce Fe-Ni alloy and Ni matte. The key to achieving the highest recovery degrees from nickel ore in electric arc furnaces and producing top-quality ferro-nickel alloys lies in maintaining optimal carbon consumption and carefully controlling the composition of the slag. This research work focused on finding the optimal smelting procedure for extracting ferro-nickel from calcined nickel ore. Comparing experimental data to the results of thermodynamic modeling using Factsage 8.2 software was a key part of the study. The nickel smelting process, which involved a carbon consumption of 4 wt.%, resulted in ferro-nickel with an Fe/Ni ratio of 4.89 and slag with a nickel content of just 0.017%. The structure and properties of nickel slag in the MgO-SiO₂-FeO system were investigated by observing the changes in the MgO/SiO₂ ratio. This study found a significant nickel recovery degree of 95.6% within the optimal M/S ratio range of 0.65 to 0.7. When the M/S ratio exceeds 0.7, iron-rich magnesium silicates (Mg_xFe_ySiO_2+n) are generated within the slag. These compounds are released downwards due to their higher specific weight, restricting the movement of small metal particles and contributing to increased metal loss through the slag. Optimized slags could revolutionize smelting, increasing metal recovery while minimizing environmental impact. Full article

To investigate the effect of NiCrTi coating on the ash condensation characteristics of high-alkali coal in Xinjiang South Mine, we first built an experimental rig for high-alkali-coal flue gas condensation and carried out experimental research on high-alkali-coal flue gas condensation. Physicochemical characterization of the initial layer of the ash deposit (initial deposit) condensation products was also carried out using XRD, SEM, and EDX. Finally, the priority of products generated on the surface of NiCrTi coating and the three-phase diagram of Na₂O-SiO₂-Al₂O₃ were analyzed by using FactSage 8.3 thermodynamic software. The results show that the condensation products in the initial deposits layer of 15CrMo alloy contain other sodium salts, such as sodium feldspar (NaAlSi₃O₈), NaCl, and Na₂SO₄, and that other protective oxides, such as Cr₂O₃, NiCr₂O₄, and TiO₂, are formed on the surface of the NiCrTi coating. At the same time, the condensation experiment allows the fouling phase to be divided into four parts. Secondly, it was found that the densely flaky particles on the surface of NiCrTi coatings not only have excellent anti-fouling properties but also can effectively inhibit the penetration of other elements such as S. Finally, the reaction priority of protective oxides on NiCrTi coatings was calculated by FactSage 8.3 and found to have the following order: NiCr₂O₄ > Cr₂O₃ > TiO₂. The results of this paper provide theoretical support for the development of anti-staining NiCrTi coatings. Full article

Custom copper smelters, which are dependent on purchased concentrates, are facing increasing economic pressures amid falling treatment and refining fees. With the declining availability of high-grade, low-impurity concentrates, copper demand is expected to surge to support the transition to renewable energy. This study, which is based on recent observations of Chinese custom smelters, examines their strategies to address the challenge of purchasing concentrates at record-low treatment and refining charges. By investing in slag flotation technology, smelters can enhance copper, gold, and silver recovery. By blending high-grade and low-grade concentrates, they can capitalize on the gap between the recoverable and payable metals, which are often referred to as “free metals”, while also benefiting from byproducts, mainly sulfuric acid. While this approach offers economic opportunities, it introduces operational complexities. To mitigate these, laboratory testing, combined with advanced digital predictive tools based on thermodynamics, is crucial. This study demonstrates the use of thermodynamic models supported by experimental work for analyzing furnace operations. FactSage^® software and a custom database are employed to define the operating window of two common flowsheets: (1) flash smelting + flash converting and (2) bottom-blown smelting + bottom-blowing converting. Full article