Search Results (58)

A mass action concentration model of FeO-Fe₂O₃-SiO₂-CaO-MgO-Al₂O₃-ZnO multi-component slag was established to address the problems of high viscosity and high copper content in oxygen-enriched top-blown copper smelting slag. Theoretical calculations, combined with experimental investigations, were performed to evaluate the effects of ZnO additions (0–25 wt.%) on phase transformation, Fe₃O₄ reduction and copper content in the slag at temperatures ranging from 1200 to 1400 °C. The results indicate that ZnO addition decreases the mass concentrations of Fe₂O₃, Fe₃O₄, Fe₂SiO₄ and SiO₂, while increasing the proportions of zinc-bearing structural units and enhancing the reducing capability of the slag. In the copper slag system, Zn²⁺ substitutes for Fe in Fe₃O₄ and Fe₂SiO₄ through isomorphous substitution, forming Fe-Zn spinel and Fe-Zn olivine. As the addition of ZnO gradually increases to 25 wt.%, the liquid slag fraction increases and the slag viscosity decreases, resulting in a reduction in copper content from 5.64 wt.% to 2.04 wt.%. Furthermore, ZnO promotes the transformation of Fe₃O₄ into zinc–iron spinel, which is more readily reducible by carbothermic reaction than Fe₃O₄ itself, thereby facilitating the overall reduction of iron oxides in the copper slag. These findings provide a theoretical basis for slag-type regulation and the efficient separation of copper from slag via high-temperature gravity settling of matte. Full article

Ceramics, as a handicraft, is the crystallization of art and science. In order to study the firing process of ceramics, improve their density, mechanical properties, viscosity, and surface tension, and enhance the surface quality of the shaft, this article uses first-principles methods to study the electronic properties of ceramic colorants Al₂O₃, Fe₂O₃, TiO₂, CaO, MgO, Na₂O, KO₂, and ceramic body SiO₂. Research has shown that these seven color-developing agents exhibit anisotropy and have stable crystal structures. The bandgap values of Al₂O₃, CaO, Fe₂O₃, KO₂, MgO, Na₂O, TiO₂, and ceramic SiO₂ are 6.325 eV, 3.654 eV, 0 eV, 0 eV, 4.731 eV, 1.972 eV, 2.18 eV and 6.002 eV, respectively. In Al₂O₃/SiO₂, Fe₂O₃/SiO₂, TiO₂/SiO₂, CaO/SiO₂, MgO/SiO₂, Na₂O/SiO₂, and KO₂/SiO₂ systems, due to the influence of the potential field in the SiO₂ system, the charge characteristics exhibit obvious interfacial and non-periodic characteristics. The research results revealed the charge transfer and distribution patterns at the interface between ceramic colorants and ceramic ligands, elucidating the influence mechanism of different colorants/embryo components on firing temperature, shrinkage rate, and finished product defects. This mechanism can be used to predict the advantages and disadvantages of alkali metals, iron, titanium, and aluminum components in raw materials, optimize low-temperature rapid firing formulas, suppress firing deformation, control pore defects, and improve the mechanical properties of finished products. It provides micro theoretical support for the industrialization, stabilization, and high-quality production of local ceramics in southwestern China. Full article

Against the background of blast furnace burden optimization and the low-carbon transition of the steel industry, the development of high-quality Mg-bearing fluxed pellets is of great significance for the efficient utilization of medium-high silica iron ore concentrates. In this study, Mg-bearing medium-high silica fluxed pellets with a fixed SiO₂ content of 5.5% were prepared, and the effect of basicity in the range of R = 1.0–1.4 on compressive strength, liquid phase behavior, slag phase composition, and pore structure evolution was systematically investigated. The results showed that the compressive strength of the pellets decreased from 2527 N/pellet to 2079 N/pellet as the basicity increased from 1.0 to 1.4. At 1250 °C, the liquid phase content first decreased from 2.66% to 1.30% and then increased to 7.38%, while the liquid phase viscosity decreased continuously. Meanwhile, the liquid phase composition evolved from a SiO₂-rich calcium–iron silicate system to a Fe₂O₃⁻ and CaO-rich system. XRD results indicated that Fe₂O₃ was the dominant crystalline phase in the pellets, accompanied by a small amount of Fe₃O₄, whereas no distinct highly crystalline slag phase was detected. The slag phase was mainly a Fe-Ca-Si composite slag, in which the Fe₂O₃ content increased and the SiO₂ content decreased with increasing basicity. At higher basicity, the number and size of pores increased, and the pore morphology evolved from dispersed fine pores to irregular large pores and locally connected pores. Meanwhile, the slag phase became more widely distributed and locally enriched, weakening the continuity of the iron oxide load-bearing skeleton, which was the main reason for the decrease in compressive strength. This study provides a theoretical basis for preparing high-quality Mg-bearing fluxed pellets from medium-high silica iron ore concentrates. Full article

The cohesion zone of a blast furnace is instrumental in determining the gas-dynamic regime and the efficiency of reducing gas utilization. The extent of this phenomenon is contingent upon the initial and final temperatures at which iron ore undergoes softening, which, in turn, are determined by the chemical and phase composition, as well as the degree of reduction of the charge. The present study investigated sinter with a basicity (CaO/SiO₂) ranging from 1.2 to 3.0 using a combination of methods. The experimental program involved the use of X-ray diffraction (XRD) with refinement using the Rietveld method, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and load-dependent softening tests. It was established that as the basicity increased, the content of the calcium–aluminum silicoferrite (SFCA) binder phase increased from 6.2 to 17.5 wt.%, whilst the amount of hematite decreased from 12.6 to 2.3 wt.%. The softening onset temperature increases from 1185 to 1260 °C, the softening end temperature from 1345 to 1415 °C, and the softening interval narrows from 160 to 155 °C. The evolution of the phase composition of sinter during controlled reduction (0–95%) has been investigated for the first time. It has been demonstrated that the maximum accumulation of wustite (FeO) is attained at a reduction degree of 40–60%, irrespective of the basicity of the substance. It is precisely in this range that the minimum softening start (1040–1065 °C) and end (1170–1210 °C) temperatures are observed, which is associated with the formation of low-melting eutectics. The sinter belongs to the CaO–SiO₂–FeO–Al₂O₃–MgO system, and the softening behavior is governed by the FeO–CaO–SiO₂ system where low-melting eutectics form. When the reduction rate exceeds 60%, the metallic phase becomes dominant, leading to an increase in softening temperatures and a narrowing of the cohesion zone. It is evident from the data obtained that the optimal basicity range of the sinter is 2.0–2.5. Furthermore, it is recommended that a reduction degree of at least 60% is implemented in order to improve gas dynamics and increase blast furnace productivity. The findings can be utilized to enhance the efficiency of charge materials and refine mathematical models of the blast furnace process. Full article

Glazes primarily utilize raw minerals like kaolinite. However, considering sustainable development, employing industrial solid waste offers greener design solutions and high economic efficiency. This study employs multiple analytical methods, including XRF, XRD, and SEM, to investigate the feasibility of replacing traditional glaze materials entirely with solid waste. It elucidates the mechanisms underlying changes in texture and color resulting from alterations in microstructure and chemical composition. Research on five different ratios of ceramic glaze composed of fly ash, blast furnace slag, silica fume, coal gangue, and desulfurization gypsum reveals that the implementation of solid waste-based glazes is feasible. The glazes formed a SiO₂–Al₂O₃–CaO system surface, all exhibiting anorthite and diopside as the primary crystalline forms. The results are as follows: 1. The content of Ca and Mg depends on the overall proportion of elements, with a Ca threshold of approximately 28%. Below this threshold, characteristics such as surface roughness and porosity are observed. Above this threshold, as seen in G3 and G4, crystal distribution becomes more dense. 2. Si is the key factor controlling crystal variation. Sample G5 exhibits good crystal continuity. Visually, its color appears distinctly deep red. 3. Samples G1 and G2 both contain approximately 4.8 wt% Fe₂O₃, but G2 exhibits more crystalline precipitation. Visually, G2 appears more reddish-yellow than G1. Higher crystallinity yields superior coloration. Full article

This study investigates the thermodynamic and experimental aspects of producing a chromium–manganese ligature under high-temperature smelting conditions using low-grade iron–manganese ore and ferrosilicochrome (FeSiCr) dust as both a reducing agent and a chromium source. Thermodynamic modeling of the multicomponent Fe–Cr–Mn–Si–Al–Ca–Mg–O system was carried out using the HSC Chemistry 10 and FactSage 8.4 software packages to substantiate the temperature regime, reducing agent consumption, and conditions for the formation of a stable metal–slag system. The calculations indicated that efficient reduction of manganese oxides and formation of the metallic phase are achieved at a smelting temperature of 1600 °C with a reducing agent consumption of approximately 50 kg. Experimental smelting trials conducted in a laboratory Tammann furnace under the calculated parameters confirmed the validity of the thermodynamic predictions and demonstrated the feasibility of obtaining a concentrated chromium–manganese ligature. The resulting metallic product exhibited a high total content of alloying elements and had the following chemical composition (wt.%): Fe 35.41, Cr 41.10, Mn 8.15, and Si 4.31. SEM–EDS microstructural analysis revealed a uniform distribution of chromium and manganese within the metallic matrix, indicating stable reduction behavior and favorable melt crystallization conditions. The obtained results demonstrate the effectiveness of an integrated thermodynamic–experimental approach for producing chromium–manganese ligatures from low-grade mineral raw materials and industrial by-products and confirm the potential applicability of the proposed process for complex steel alloying. Full article

According to the production process requirements of oriented silicon steel in a certain steel mill, optimization of the slag composition ratio is studied through thermodynamic calculations. The CaO-SiO₂-Al₂O₃-FeO-MgO slag system is studied using FactSage thermodynamic software (FactSage 8.1), and a slag optimization plan is proposed based on industrial experiments involving changes in the composition ratio of the slag, calculation and analysis of the melting characteristics of RH refining slag, further verification through orthogonal experiments, and observations of the slag state, temperature, and composition relationship through phase diagrams. This study provides theoretical guidance for finding a suitable slag composition ratio based on the influence of slag on dissolved aluminum in steel liquid. Research has shown that, combined with thermodynamic analysis, slag melting characteristics, component content calculations, and industrial experiments, the range of RH refining slag composition suitable for production in this steel mill is slag in the range of 1.3~1.5 alkalinity, 25~30% Al₂O₃, 5~6% MgO, and 1–2% FeO. Full article

This study utilizes the temperature–pressure reactor to simulate the real conditions of the reservoir to study rock dissolution and scale formation caused by strong and weak alkali during the ASP flooding in an oilfield in China. Mercury injection experiments showed that the porosity and permeability of rock increased by 10.3% and 15.3% under the action of strong alkali, while they increased by 7.2% and 10.1% under the action of weak alkali, indicating that both strong and weak alkali can cause rock dissolution. The structural morphology of the rock demonstrated that the clay content between the grains decreased significantly. The semi-quantitative analysis of XRD indicated that the content of kaolinite decreased from the initial 7% to 0%. The recrystallized carbonate was found, and the carbonate content increased from the initial 0% to 12%. According to the SEM, EDS, and Raman analyses of the scale, the scale formation was complex in the strong alkaline system, including silicate scale, carbonate scale, and hydroxide scale. In contrast, only carbonate scale was found in the weak alkaline system. The ICP-AES test for the liquid system revealed that the rock dissolution releases substantial Ca²⁺, Mg²⁺, Fe²⁺, SiO₃²⁻ and AlO₂⁻ ions, among which Si concentration can reach around 560 ppm. The chemical mechanism of rock dissolution and scale formation by strong and weak alkali includes the exchange of mineral cations by Na⁺ and the destruction of Si-O and Al-O bonds by OH⁻. These released ions migrate with the composite fluid, then recrystallize under the saturation state to form the scale. The dissolution of rock by strong alkali is more intense, while the dissolution of weak alkali is relatively mild. Moreover, the scale type in the weak alkaline system is simpler, which would be convenient to develop inhibitors. Full article

A new molecular theory of slag suggests that complex oxides in the phase diagram are also present in liquid slag. In contrast to the ion‒molecule coexistence theory, basic oxides (CaO, MgO, MnO, FeO, etc.) in slag are considered to agglomerate in the liquid state due to their strong mutual attraction, although they are ionized (M²⁺ and O²⁻). The predicted slag structure agrees with the experimental results, and when the model is applied to the CaO-SiO₂, CaO-Al₂O₃, and CaO-SiO₂-Al₂O₃ slag systems, the calculated molar fractions of CaO, SiO₂, and Al₂O₃ ($N_{\mathrm{CaO}},N_{{\mathrm{SiO}}_2},N_{{\mathrm{Al}}_2{\mathrm{O}}_3}$) are close to the measured activities (${\alpha }_{\mathrm{CaO}},a_{{\mathrm{SiO}}_2} \mathrm{and} a_{{\mathrm{Al}}_2{\mathrm{O}}_3}$) reported by different researchers. In the CaO-Al₂O₃ slag system, the results based on the new molecular theory are closer to the experimental values than the results of other theoretical calculations. In the practical application of the new molecular theory, the maximum concentration of each complex molecule is consistent with the position of the melting point of the same solid‒liquid components in the phase diagram, indicating that complex molecules have a strong influence on the melting point of slag. In addition, it is believed that the formation and decomposition of different complex molecules are responsible for changes in component activity in the CaO-SiO₂ and CaO-Al₂O₃ slag systems, and it is further deduced that 3CaO-SiO₂ is formed in two steps. Full article

This paper introduces a new methodology for a routine metal analysis of plastic waste (PW) and PW blended with petroleum feedstock such as vacuum gas oil and VGO (PW/VGO). For such purposes, recycled polyethylene and polypropylene plastic were selected to mimic the potential feeds to be integrated at the Fluid Catalytic Cracking unit (FCC) to produce valuable products. Elements such as P, Ca, Al, Mg, Na, Zn, B, Fe, Ti, and Si were included in the method development. Different sample preparation methods were evaluated, such as microwave-assisted acid digestion (MWAD) and dry/wet ashing, followed by a fusion of the ash with lithium borate flux. Some PW homogenization pretreatments, such as cryogenic grinding and hot press molding, were also covered. The finding of this work suggests that MWAD with HNO₃ and H₂O₂ is adequate for both types of samples and is the quickest sample preparation; however, the sample needed to be homogenized, and recoveries for Si and Ti may be biased for PW due to the limited solubilities of these elements in the nitric acid media. Carbon removal is required before fusion sample preparation and analysis due to the amount of carbon in PW samples. The sample needed to be homogenized for wet ash fusion but not for the pre-ash (dry) method. A benefit to the damp ash pretreatment is that the ash for the sample was created in the same crucible used for fusion digestion, avoiding material loss during sample management. Fusion from wet ash or carbon removal allowed for better acid solubility for Si and Ti in PW. The results of the PW samples evaluated matched well with those of both sample preparation methodologies. For most elements, precision was <10% regardless of the sample preparation; however, Fe and P had some variation using wet ash fusion, possibly due to contamination in an open digestion system or variation due to being close to the method limit of quantification (LOQ). The methodology reported here is robust enough to be implemented as routine analysis in any laboratory facility. Full article

In this study, the thermodynamic simulation model and system of the copper side-blown smelting process were established using the chemical equilibrium constant method, based on the process reaction mechanism, multiphase equilibrium principle, and MetCal software platform (MetCal v7.81). Under typical production conditions, the composition of the product and the distribution behavior of impurity elements were simulated. The results indicate that the average relative error between the calculated mass fractions of major elements such as Cu, S, Fe, SiO₂, CaO, MgO, and Al₂O₃ in copper matte and smelting slag, and the actual production values, is 4.25%. Additionally, the average relative error between the calculated distribution ratios of impurity elements such as Pb, Zn, As, Bi, Mo, Au, and Ag in copper matte and smelting slag, and the actual production data, is 6.74%. Therefore, this model and calculation system accurately reflects the actual production situation of the copper side-blown smelting process well and has potential to predict process output accurately while optimizing process parameters, effectively guiding production practice. Full article

Traditional rock wool fibres are susceptible to crystallization and pulverization. To mitigate this, glass fibres were produced from iron ore waste (IOW). When the ratio of Fe²⁺ and Fe³⁺ is 1:3 and the Al₂O₃ content is 10 wt.%, increasing the Fe_xO_y content enhances the thermal stability.At an Fe_xO_y content of 17–19% and an Al₂O₃ content of 10–13%, the glass transition temperature (Tg) peaked. Increasing the Fe_xO_y content from 10% to 20% enhanced the stability of Si-O and Al-O bonds and increased bridged oxygen, stabilizing the structure. Here, Fe²⁺ balances structural charges, while Fe³⁺ replaces some Al atoms in the network. When the Al₂O₃ content is 10–13% and the Fe_xO_y content is 17–19%, the thermal stability of the IOW rock glass reaches its optimal level. At 20% Fe_xO_y content, the structure becomes three-dimensional and cyclic, increasing polymerization. Consequently, incorporating Fe_xO_y alongside a 10% Al₂O₃ content improves thermal stability, supporting the development of high-stability rock wool from IOW. This approach also enhances the refractory properties of rock wool fibres within the Fe_xO_y-Al₂O₃-SiO₂-MgO-CaO system. Full article

Pyrometallurgy is the primary technique for the production of many nonferrous metals such as copper, lead, and zinc. The phase equilibrium information of smelting slags plays an important role in the efficient extraction of metals and energy consumption. The experimental technologies used in phase equilibrium studies are compared. The presentation and applications of the pseudo-ternary and pseudo-binary phase diagrams are demonstrated in the Fe–Si–Ca–Zn–Mg–Al–Cu–S–O system. Experimental results are also compared with the predictions of FactSage to evaluate the accuracy of the current thermodynamic database. This review paper provides comprehensive information for the operation of nonferrous metals and optimization of the thermodynamic database. Full article

Within the Ca-Al-silicate system, dense, layered hexagonal phases occur at high temperatures and pressures between 20 and 23 GPa. They have been observed both in nature and in experiments. In this study, we describe the endmember with a dominant sixfold coordinated Si as a mineral zagamiite (IMA 2015-022a). This new mineral identified in Martian meteorites has a general formula of (Ca,Na)(Al,Fe,Mg)₂(Si,Al,□)₄O₁₁, thus defining CaAl₂Si_3.5O₁₁ as a previously unknown endmember of the hexagonal CAS phases. Zagamiite assumes space group P6₃/mmc with a unit cell of a = 5.403(2) Å, c = 12.77(3) Å, V = 322.9(11) ų, and Z = 2. Zagamiite contains significant Fe and Mg and a substantial deficit of Na relative to plagioclase of an equivalent Al/Si, suggesting that it was formed through crystallization from a melt that was derived from a plagioclase-dominant mixture of plagioclase and clinopyroxene above the solidus beyond 20 GPa. Full article

Steel slag waste produced by the steel industry accumulates in open areas or is disposed of in landfills, causing harm to the environment and human health. Valorizing steel slag through comprehensive data analysis is imperative and could add value to the product with respect to energy conversion and storage applications. This study investigated the morphological, structural, and optical characteristics of a thermally annealed steel slag composite generated from iron and steel factories. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, and UV–visible spectrophotometry were subsequently used to evaluate the impact of thermal treatment on the morphology, structure, elemental composition, and optical properties. It was found that the pre-treated slag composites contained a variety of irregular grain sizes and microscale fragments, primarily composed of C (18.55%), O (50.85%), and Fe (29.41%), with lower amounts of Mg (0.31%), Si (0.44%), and Ca (0.44%), indicating the natural formation of a disordered iron composite. Thermal treatment at different temperatures (300 °C, 600 °C, and 900 °C) increased the grain density and clustering, resulting in denser two-dimensional microstructures at 900 °C. Additionally, XRD and Raman analyses of both untreated and thermally treated slag composites revealed the presence of a disordered iron oxide composite, including (Fe₃O₄), hematite (α-Fe₂O₃), and maghemite (γ-Fe₂O₃) phases. A significant increase in optical absorbance was also observed after annealing at 600 °C, highlighting the successful optimization of the elemental composition of the slag composite. A band gap energy of approximately 2.2 eV was obtained from this optimization at 600 °C. The optical conductivity of the composite reached 2.1 × 10⁶ S⁻¹ at 600 °C, which indicates an enhancement in charge transfer among the optimized chemical elements in the waste composite. These findings suggest an optimization method for novel composites derived from steel slag waste, indicating its potential as a low-cost material for energy storage systems (batteries, supercapacitors, and fuel cells) and optoelectronic devices. Full article