Fe2O3 SiO2 Research Articles

Sulfide Capacity and Activity of Iron Oxide in CaO–SiO<sub>2</sub>–FeO Ternary System at 1573 K

The knowledge of sulfide capacities of FeO-containing slags is necessary for better understanding the resulfurization reaction in hot metal pre-treatments. In this study, copper-iron-sulfur liquid alloy was equilibrated with CaO–SiO2–FeO ternary slag to measure sulfide capacities and FeO activities simultaneously at temperature below the melting point of pure iron. The experimental result that the sulfide capacity increased with increasing FeO content could be explained by the fact that FeO was a basic oxide, and the sulfide capacity of the CaO–SiO2–FeO ternary system was significantly larger than those of the CaO–SiO2–MgO, CaO–SiO2–AlO1.5 and CaO–SiO2–CaF2 ternary systems. Although the FeO activity and oxygen potential were raised by the FeO addition, the calculated value for sulfur distribution ratio between CaO–SiO2–FeO slag and hot metal increased with an increase in FeO content.

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.

Thermodynamic analysis of processes in the high-temperature polycomponent Fe–Y–Si–O–C system

In the production of low-carbon and high-quality steels, it is recommended to use special complex alloys of rare earth metals for deoxidation, microalloying and modification. To elucidate the mechanism of action of each of the components of the alloy, it is necessary to differentiate the action of each individual element. Yttrium is usually classified as a rare earth metal, but its deoxidizing and modifying ability deficiency studies. The use of yttrium applica-tion is known to increase in density, ductility, scale resistance, resistance to high-temperature corrosion of steel, effec-tively affects the shape, size and distribution of non-metallic inclusions. This paper consider the interaction of yttrium, silicon, and carbon with oxygen dissolved in liquid iron. Nonmetallic inclusions formed in this case can be identified on the state diagram of the FeO–Y2O3–SiO2 oxide system. This diagram is absent in the literature; therefore, it was mod-eled on the basis of the available binary phase diagrams of the FeO–Y2O3, FeO–SiO2, and Y2O3–SiO2 systems. Com-plex deoxidation by yttrium and silicon is possible only at yttrium concentrations in liquid iron less than 0.0001% (ox-ide melt or yttrium silicates are formed as non-metallic inclusions). If the concentration of yttrium is higher than this value, then it is the only deoxidizer. In the presence of carbon, liquid non-metallic inclusions can form in a very narrow range of liquid metal compositions, and the main oxide non-metallic inclusion is yttrium oxide. At yttrium concentra-tions below 0.0001% and silicon concentrations up to 1%, only carbon is the deoxidizer. Taking into account the previ-ously studied Fe–Y–Me–O–C (Me–Ca, Mg, Al, Cr) systems, a thermodynamic data base was created for designing the compositions of complex yttrium-containing ligatures.

The sensitive mobility of Cr in ashes studied by SiO2–Al2O3–Fe2O3–CaO system

Since incineration is a feasible method for stabilization/solidification of chromium (Cr)-enriched wastes, the species, distribution, and mobility of Cr in ashes deserve more studies, especially as the function of ash composition. Synthetic Cr-bearing ashes (SAs) were synthesized by SiO2–Al2O3–Fe2O3–CaO systems to investigate Cr mobility under 1100 °C. A study from simplicity to complexity. The Cr in SiO2–CaO is of high mobility with CrO42− formation, in contrary to the moderate mobility in SiO2–Al2O3 and poor mobility in SiO2–Fe2O3. However, species and mobility of Cr are affected by the values of CaO/SiO2, Al2O3/SiO2, and Fe2O3/SiO2 ratios. When other oxides are added to the two-phase systems above, the fate of Cr is affected more considerably. With the SiO2 content of 70%, adding a slight amount of CaO (<10%) strengthens the stabilization/solidification of Cr, due to the favorable solid integration under Ca2+ fusion. However, the Cr mobility is higher with increasing the CaO content further. The minimum content of CaO is ∼20% to sufficiently decrease the proportion of residual Cr (QCr-S5) in SiO2–Al2O3–CaO, much lower than in SiO2–Fe2O3–CaO, which confirms the easier release of Cr immobilized in Si–Al matrixes. Considering the opposite effects of Fe2O3 and CaO on Cr mobility, increasing Fe2O3/CaO ratios >3/2 can limit the effect of CaO, leading to the efficient stabilization/solidification of Cr waste. Additionally, the QCr-S5 is 83% with the Fe2O3 content of 15% in SiO2–Al2O3–Fe2O3, higher than in SiO2–Al2O3 and SiO2–Fe2O3. This suggests the intense stabilization/solidification of Cr, probably due to the formation of amorphous Fe-rich glass. Based on these above, an equation is developed to describe the relationship between ash compositions and QCr-S5 (QCr-S5 = −39.37X1 + 24.96X2 + 5.34X3 – 2.51X4 + 54.29).

Influence of oxides on the formation of self-lubricating layer and anti-wear performance during sliding

Oxides are the key roles on the formation of self-lubricating layer (SLL) with anti-wear performance. In present study, dry sliding wear tests of 00Cr13Ni4Mo steel were performed to investigate the influence of oxides on SLL. The formation of SLL with different oxides was comparatively analyzed by the cross-sectional and surface morphologies. Mechanism of oxides on the integrity of SLL and anti-wear performance is discussed. It is confirmed that Cr-oxide, Fe3O4 and suitable SiO2 are the key to endow SLL with good self-lubricating performance while FeO, Fe2O3 and excessive SiO2 are opposite, good integrity of SLL is the prerequisite for anti-wear.

Geochemistry of Kolme granitoids: Implication for crustal growth in the Mozambique orogenic belt of southwestern Ethiopia

Petrological and geochemical (major and trace element) data are presented for Kolme granitoid from the Precambrian terrain of southwestern Ethiopia. Integrated field and petrochemical studies have been carried out to assess the source and discriminate tectonic setting of the granitoid as well as evaluate their implication for crustal growth. The petrological and the geochemical data indicate the presence of two groups of granitoid in the area: Borkara granitoid (BG) and Matera granitoid (MG). BG is granite in composition with higher SiO2 content (75.27–78.51 wt %), lower Al2O3 (13.05–13.45 wt %), and FeO*/(FeO*+MgO) ꞊ 0.92–0.94 wt %. BG is a high-K calc-alkaline, peraluminous, ferroan, and felsic I-type granitoid. Whereas MG is quartz-monzonite in composition with lower SiO2 (66.03–69.16wt %) and higher Al2O3 (14.85–16.25 wt %) and FeO*/(FeO*+MgO) (0.96–0.97wt %). MG is shoshonitic, metaluminous to peraluminous, alkalic, ferroan and mafic I-type granitoid. BG is derived from the partial melting of upper continental crust with the contribution of melts from subducted slab and asthenospheric mantle wedge, while MG is derived by fractional crystallization of mantle-derived mafic magma underplated in the lower crust with minor crustal involvement.The tectonic discrimination diagrams for Kolme granitoid infer that BG is a syn-orogenic granitoid, while the MG is a post-orogenic granitoid. Moreover, the transition from syn-orogenic calcic-alkalic BG magmatism to alkalic MG magmatism is marking the end of the syn-collisional stage and the beginning of the extension of the Neoproterozoic crust.

Evaluation of Phosphorus Enrichment Capacity of CaO–SiO2–FeO–MgO–MnO–P2O5–Al2O3 Dephosphorization Slag Based on Ion‐Molecule Coexistence Theory

Herein, the phosphorus enrichment capacity of CaO–SiO2–FeO–MgO–MnO–P2O5–Al2O3 dephosphorization slag is studied based on ion‐molecule coexistence theory (IMCT) and industrial experiment. The equilibrium mass percentages of structural units in dephosphorization slag have different degrees of linear relationship with the corresponding mass action concentrations N i . The calcium phosphate in dephosphorization slag has the greatest contribution to phosphorus distribution ratio and phosphate capacity, up to 99.99%, in which 3CaO·P2O5 has about 94.97%. Compared with the other 23 phosphorus distribution ratio and 7 phosphate capacity empirical models, IMCT model can accurately predict the phosphorus distribution ratio with the lowest average relative error of 3.70% and the second lowest standard deviation of 2.34%, and phosphate capacity with the lowest average relative error of 0.80% and the lowest standard deviation of 0.52%. At 1620–1640 °C, with increasing phosphorus enrichment contribution ratio of 2CaO·SiO2 in slag, the dephosphorization capacity of slag is greatly improved. The change trends of phosphorus enrichment capacity evaluation indexes of slag calculated based on IMCT are well consistent with the change trend of dephosphorization ratio of molten steel, indicating the IMCT calculation results can correctly predict the phosphorus enrichment capacity of dephosphorization slag in converter dephosphorization process.

Effect of Oxygen Partial Pressure and B2O3 on Crystallization Behavior of Phosphorus- and Iron-Containing Phases in a CaO–SiO2–Fe2O3–P2O5 Melt

Effect of Oxygen Partial Pressure and B2O3 on Crystallization Behavior of Phosphorus- and Iron-Containing Phases in a CaO–SiO2–Fe2O3–P2O5 Melt

Archeometallurgical Study of a Renaissance Spearhead from Northern Italy

A metallurgical study of a Renaissance spearhead from northern Italy was performed to provide new deep insights into both smelting and smithing technologies which are involved in the manufacturing process. Optical microscopy observations, Vickers microhardness measurements, and optical emission spectroscopy analyses demonstrated that the spearhead was skillfully assembled and shaped from different steel bars, and a slack-quenching heat treatment was performed on the blade to improve its functionality. The chemistry of a large sample of nonmetallic inclusions was characterized by scanning electron microscopy coupled with X-ray dispersive spectroscopy. A multivariate statistical data treatment based on logistic regression was applied to assess the technological origin of the steel bars. The results allowed to conclude that the spearhead steel was obtained following the indirect steel-making route. The temperatures reached during both smelting and smithing stages were estimated in the FeO–SiO2–CaO system at 1470 °C and 1200 °C, respectively.

Density, viscosity and surface tension of high-silicate CaO–SiO2 and CaO–SiO2–Fe2O3 slags derived by aerodynamic levitation. The behavior of Fe3+ in high-silicate melts

Thermophysical data for liquid slag are required for the optimization and control of metallurgical processes. The density, surface tension and viscosity were measured by employing aerodynamic levitation under contactless conditions. The high-silicate slag (44 and 63 mass-% of SiO2) of the CaO–SiO2 and CaO–SiO2–Fe2O3 systems (with 5 and 10 mass-% Fe2O3) was investigated under (80% Ar + 20% O2) gas atmosphere. The temperature ranges were between 800 °C and 2000 °C for the density and 1500 °C–2000 °C for surface tension and viscosity measurements. The influence of the CaO/SiO2 ratio on the investigated properties and the behavior of Fe3+ ions in high-silicate melts were examined. The density of the CaO–SiO2 melt was lower than that of the CaO–SiO2–Fe2O3 systems. The surface tension of all compositions tested decreased with temperature and showed compositional dependence. The viscosity measured was higher in the Fe2O3-containing slag. The Raman spectroscopy analyses confirmed the increase in the degree of polymerization with the addition of Fe2O3 for the silicate-rich slag. The formation of a complex anion of a ferric ion and contribution to the silicate network were assumed. The trends observed were related to the structural properties and different interionic bonding. Urbain's viscosity model and FactSage™ 7.3 were applied for the assessment of the experimental data.

Occurrences of Rare Earth Element (REE) Bearing Minerals in Migmatitic Gneiss and Granitoids of Chhotanagpur Granite Gneissic Complex, Bihar, India

Abstract This paper presents the geochemical characteristics, petrogenetic processes and source characteristics of Rare Earth Elements (REE) bearing migmatitic gneiss and granitoids near Tangeshwar village, Banka district, Bihar, in order to demarcate the potential zone of REE mineralization. These migmatitic gneiss and granitoids belongs to the Chhotanagpur granite gneissic complex (CGGC). The study of migmatitic gneiss and granitoids of CGGC suggest that they have high content of SiO2, low contents of Fe2O3 and MgO and SiO2 vs. Na2O and K2O shows positive correlation which suggest, they are dominated by sodic and alkali rich minerals and were derived from a felsic (granitic) source. Also LREE-LILE enrichment, HFSE depletion and calc-alkaline nature indicates that the magmatism is related to the subduction zone. Petrographic and EPMA studies of these migmatitic gneiss and granitoids confirms the presence of REE bearing mineral phases such as allanite, xenotime, monazite, and basnasite. They are generally present at the rim of biotite, as an inclusion in biotite and also along the grain boundaries and within the cracks of major silicate minerals. This suggest that the REE formation takes place at the deuteric stage of magma crystallisation followed by the formation of granite. Chemical analysis of bed rock samples for rare earth elements using ICPMS shows that the highest concentration is in migmatitic gneiss and granitoids, which varies from 47.85- 925.67 ppm and 47.85- 626.48 ppm respectively.

The Reaction Behavior of 2CaO·SiO2 with CaO-SiO2-FeO-P2O5 Slag.

It is important to clarify the reaction behavior of 2CaO·SiO2 (C2S) during hot metal dephosphorization. In this study, C2S was prepared and added to steel slag to investigate the reaction of C2S particles with CaO–SiO2–FeO–P2O5 slag at 1723 K. The diffusion coefficient of phosphorus in C2S was calculated. In addition, the influence of the addition of BaO to C2S was discussed. The results show that the diffusion coefficient of phosphorus in C2S is 9.23 × 10−14 m2·s−1. The Ca in C2S can be replaced by Ba. Small particles in the solid solution were easily generated from the C2S body by the addition of BaO, which is beneficial for improving the phosphorus partition between the C2S solid phase and the liquid phase of the slag.

Significance of selective crystal entrainment and differential crystal‐melt separation in petrogenesis of granites from the Tongbai orogen

AbstractPartial melting has been shown to be an important mechanism for intracrustal differentiation and granite petrogenesis. However, a series of compositional differences between granitic melt from experiments and natural granites indicate that the processes of crustal differentiation are complex. To shed light on factors that control the processes of crustal differentiation, and then the compositions of granitic magma, a combined study of petrology and geochemistry was carried out for granites (in the forms of granitic veins and parautochthonous granite) from a granulite terrane in the Tongbai orogen, China. These granites are characterized by high SiO2 (&gt;72 wt%) and low FeO and MgO (&lt;4 wt%) with low Na2O/K2O ratios (&lt;0.7). Minerals in these granites show variable microstructures and compositions. Phase equilibrium modelling using P–T pseudosections shows that neither anatectic melts nor fractionated melts match the compositions of the target granites, challenging the conventional paradigm that granites are the crystallized product of pure granitic melts. Based on the microstructural features of minerals in the granites, and a comparison of their compositions with crystallized minerals from anatectic melts and minerals in granulites, the minerals in these granitoids are considered to have three origins. The first is entrained garnets, which show comparable compositions with those in host granulites. The second is early crystallized mineral from melts, which include large plagioclase and K‐feldspar (with high Ca contents) crystals as well as a part of biotite whose compositions can be reproduced by crystallization of the anatectic melts. The compositions of other minerals such as small grained plagioclase, K‐feldspar and anorthoclase in the granites with low Ca contents are not well reconstructed, so they are considered as the third origin of crystallized products of fractionated melts. The results of mass balance calculation show that the compositions of these granites can be produced by mixing between different proportions of crystallized minerals and fractionated melts with variable amounts of entrained minerals. However, the calculated modal proportions of different crystallized minerals (plagioclase, K‐feldspar, biotite and quartz) in the granites are significantly different from those predicted by melt crystallization modelling. Specifically, some rocks have lower modes of biotite and plagioclase, whereas others show lower K‐feldspar modes than those produced by melt crystallization. This indicates that the crystallized minerals would be differentially separated from the primary magmas to form the evolved magmas that produce these granites. Therefore, the crystal entrainment and differential melt‐crystal separation make important contributions to the composition of the target granites. Compared with leucogranites worldwide, the target granites show comparable compositions. As such, the leucogranites may form through the crystal fractionation of primary granitic magmas at different extents in addition to variable degrees of partial melting.

Controlling the Fe2O3–SiO2 interaction: The effect on the H2S selective catalytic oxidation and catalyst deactivation

Biogas utilization is one of the most promising options for reducing the consumption of fossil fuels for energy production, but the presence of H2S represents a serious industrial and environmental problem. In this work, two different synthesis methods (sol-gel and incipient wetness impregnation) were used to synthesize iron oxide supported on silica catalysts (Fe2O3/SiO2) with metal loadings ranging from 0.5 to 10 %wt. The catalysts were tested for the selective oxidation of H2S, changing the operating conditions like O2/H2S (0.5–2.5), temperature (170–250°C), and water content (0–50%). The optimum condition was O2/H2S = 0.5 and no water at 230 °C with the conversion of approximately 100%, the selectivity of 97%, and the deactivation of 0.6%. A detailed characterization of the fresh and spent catalysts’ surface revealed the presence of four deactivation mechanisms: metal surface reduction, oxygen vacancy loss, pore plugging, and sintering. Among the observed deactivation mechanisms, the sintering showed the highest impact on catalytic activity and deactivation. The sol-gel catalysts (SG) showed the highest metal-oxide/support interaction, which reduced the metal-oxide nanoparticles sintering compared with the incipient wetness impregnation method (IWI), reporting a lower sintering, higher activity, and selectivity, lower deactivation rates and lower sensitivity to the operating conditions. A catalytic cycle representing the possible surface intermediate states of the catalyst is proposed based on the performance and characterization results obtained.

Phase equilibria in the FeO–Fe2O3–SiO2 system: Experimental measurement and thermodynamic modeling

Knowledge about the phase equilibria of the FeO–Fe2O3–SiO2 system is very important for the resource utilization of waste slag. To solve the controversy over the calculated isothermal section at 1723 K in the literature, key experiments were carried out using equilibrium/quenching, X-ray diffraction (XRD) and electron probe microanalysis (EPMA). According to the present experiments, the existence of the three-phase region liquid + spinel (Fe3O4) + tridymite (SiO2) at 1723 K was confirmed. The ionic two-sublattice model (Fe+2, Si+4)P(O−2, Va, SiO4−4, SiO2, FeO1.5)Q was used to describe the liquid phase. The FeO–Fe2O3–SiO2 system was then critically evaluated by means of the CALPHAD (CALculation of PHAse Diagram) method in view of phase diagram and thermodynamic data. A new and improved self-consistent set of thermodynamic parameters for the FeO–Fe2O3–SiO2 system is obtained, and the calculated results show good agreement with the experimental data. The present thermodynamic modeling is of interest for the comprehensive recycling of solid waste resources.

Physical Model of Influence of CaO–FeO–SiO2 Powder Fraction on the Heat Transfer from Torch

Introduction. One of the main ways of heat transfer in metallurgical units is the interaction of the charge with a burning gas torch. The heat is transferred from the torch mainly by radiation. In particular, oxygen converter process under its typical temperature and chemical conditions of oxidation processes is accompanied by combustion reactions with the formation of a torch both in the cavity of the converter (in the so called reaction zone) and above the converter neck as a result of partial post-combustion of exhaust gases leaving the unit.Problem Statement. The processes in metallurgical units are accompanied by significant smoke and dust, which affect the efficiency of heat transfer from the torch of exhaust gases post-combustion to the metal bath that is an additional source of heat in the converter process.Purpose. The purpose of this research is to study the influence of the introduction of solid powder components into the environment around the torch on its heat transfer.Materials and Methods. The research has been carried out on the physical model of a burning torch when CaO-FeO-SiO2 system powders are fed into the torch in air flow. The magnitude of the heat flow density has been estimated on the basis of the registered temperature difference in different parts of the model.Results. It has been established that the feed of air or any solid material at a temperature much lower than the torch temperature has a negative effect on heat transfer from the torch by radiation. However, the total heat flow density is not significantly reduced due to the possible involvement of heated solids in other heat transfer methods. For the CaO-FeO-SiO2 system, the share of silicon dioxide powder as a component with the highest heat capacity has the greatest negative effect on the heat transfer from the torch.Conclusions. The studies based on the physical model have allowed us to qualitatively assess the effect of dustiness of the components of CaO-FeO-SiO2 system of the burning torch environment on its heat transfer and on the contribution of different heat transfer methods from the torch to the total heat flow density in given conditions.

Effect of P2O5 addition on enrichment behaviour of phosphorus in CaO–SiO2–FeO–P2O5 slag

ABSTRACT The CaO–SiO2–FeO–P2O5 slag was measured by Raman spectra, and the changes in the structure and behaviour of phosphorus were analysed under different slag components. The results proved that phosphorus exists in two enrichment behaviours in the slag, which can be judged according to the mole fractions of Q1(Si), Q2(Si), and Q3(Si). When the content of P2O5 increases from 4.5% to 8.5%, the Q0(P) intensity changes most significantly. Since the Fe–O bond energy (390.4 kJ mol−1) is weaker than the P–O (410 kJ mol−1) bond energy, the silicon-oxygen network structure will show a behaviour change of depolymerization first and then polymerization. XRD analysis shows that with the increase of P2O5 content, different calcium silicate phases are added and decreased in the slag, and the content of a small amount of calcium ferrite phase changes, bonds or separates from each other, which is consistent with the change law of Raman analysis.

Thermodynamic properties of geikielite (MgTiO3) and ilmenite (FeTiO3) derived from vibrational methods combined with Raman and infrared spectroscopic data

We present a model for the lattice vibrational density of states of MgTiO3 (geikielite) and FeTiO3 (ilmenite) that predicts thermodynamic properties, in agreement with observational data. The model is based on Kieffer’s method combined with spectroscopic data. For both substances experimental data sets are influenced by non-stoichiometry. For geikielite that affects the volume, whereas for ilmenite volume and bulk modulus are affected. We show that Kieffer’s method enables predicting bulk moduli in pressure–temperature space. We demonstrate that intrinsic anharmonicity or electronic effects significantly affect the heat capacity of ilmenite, whereas that is not the case for geikielite. We use Kieffer’s method to derive multiple-Einstein models, from which we demonstrate that thermodynamic properties are insignificantly influenced by dispersion in Grüneisen, mode-q and anharmonicity parameters for both substances. We show that our results enable predicting thermodynamic properties and shear modulus of the solid solution formed from geikielite and ilmenite. Geikielite and ilmenite are added to our thermodynamic database for the system MgO–SiO2–FeO, to enable modeling phase stability and physical properties of titanium-rich reservoirs in the Earth’s Moon.

Oxidized pellets production from stainless steel solid wastes: induration characteristics and harmful elements migration behavior

Stainless steel solid wastes (SSSW) treatment and recycling has attracted wide attention in recent years because of more stringent environment laws and regulations. Recycling of SSSW through carbothermal reduction of chromite (SRC)-electric furnace (EF) process is favorable to the effective treatment of SSSW and recovery of valuable elements. In this paper, SSSW are used to manufacture sufficiently strong oxidized pellets with the coexistence of chromite concentrates for ferrochrome production based on the SRC-EF process. The induration characteristics and harmful element migration behavior during oxidation of pellets are investigated and revealed. It is found that the oxidized pellets made from 100% SSSW possess low mechanical strength. Increasing the ratio of chromite concentrate from 0% to 80% can significantly improve the pellet strength from 460 N/pellet to 1868 N/pellet when preheating at 1000 °C for 12min and roasting at 1275 °C for 15min. Oxidized pellets made from SSSW and chromite are mainly dominated by the solid-phase consolidation due to the recrystallization of iron-rich spinel phases and sesquioxide derived from oxidation of ferrous oxides. In addition, slag bonding of CaO–CaF2–SiO2–FeO system also plays an important role in the consolidation of oxidized pellets. As for pellets made from 32% SSSW and 68% chromite concentrate, 39.96% F, 91.06% S, 66.73% Cl can be removed from the pellets when preheating at 1000 °C for 12 min and roasting at 1275 °C for 15 min.

Metallurgical Wastes as Resources for Sustainability of the Steel Industry

The industrial pollution caused by metallurgical waste accumulation has a negative impact on the three environmental factors: soil, air and water. Therefore, the correct management of these wastes would lead to: protection of the environmental factors, the saving of natural resources and sustainability of the steel industry. The purpose of this paper is to assess the chemical and mineralogical compositions of metallurgical wastes landfilled in the Păgida slag dump (Alba County, Romania), for sustainability of the steel industry and metal conservation. The chemical compositions of the two waste samples were analyzed by the XRF (X-ray fluorescence) technique. According to the chemical characterization, magnesium oxide (MgO) has potential to be used as an additional and raw material in the cement industry. The presence of oxides such as CaO, SiO2 FeO and Al2O3 in the compositions of the metallurgical waste samples indicate that they have the potential for use as clinker materials in cement production. The iron and manganese contents from metallurgical wastes can be reused in the iron and steel industry. The presence of V2O5 and TiO2 is connected with the making of stainless steel, and for this reason they have the potential to be reused in the stainless steel industry. The predominant chemical compounds are SiO2, Fetotal, Cao and MgO. The mineralogical compositions were analyzed by the XRD (X-ray diffraction) technique. The mineralogical compounds presenting reuse potential in different domains are Fayalite, Magnetite, Magnesioferrite and Periclase. The mineralogical compounds from metallurgical wastes can be reused as: raw and/or additional materials in the process from which they originate (steelmaking); raw and/or additional materials in road construction and concrete production; pigments in paints; micronutrients in fertilizers; ore of iron, etc. Then, the theoretical assessments of the recovery potentials of the metals were estimated for slag dumps. Copper (Cu), vanadium (V), molybdenum (Mo) and nickel (Ni) have high recovery potential. The total economic value of the recovery potential of metals from slag dumps was assessed to be USD 1175.7440 million.