MnO SiO2 Research Articles

Carbide Capacity of CaO–SiO2–MnO Slag for the Production of Manganese Alloys

The carbide capacity of the CaO–SiO2–MnO slag, which is the main system produced during Mn alloys processes, through the wide composition region has been measured at 1773 K to understand the effective slag composition on the solubility of carbon in molten slags during SiMn production processes. The carbide capacity is strongly affected by slag composition and this tendency can be reasonably estimated by employing the activity of lime and the activity coefficient of CaC2 as a thermodynamic factors affecting carbide capacity. Considering the high concentration of MnO during SiMn smelting process, the lime to silica ratio of 0.8 (±0.1) is recommended in view of high ability of carbon dissolution. The carbide capacity of the CaO–SiO2–MnO slag can be expressed as a linear function of the activity of lime and the optical basicity. The carbide capacity of the CaO–SiO2–MnO slag increases more significantly than the sulfide capacity does as the basicity of the slag increases.

A study on the interfacial tension between solid iron and CaO–SiO2–MO system

Interfacial tension is an important property that plays an essential role in understanding wetting behavior between refractories–molten slag–steel in the steelmaking process. Most work on interfacial tensions of molten slag system have been done to clarify the effect of surface active elements in molten metal and slag composition, but there has been little work done with respect to the slags ionic structure. In this study, the interfacial tension between molten slag and solid Fe was investigated to understand the effect of the ionic structure of molten slag on interfacial tension by using solid Fe instead of molten steel. Interfacial tension measurements in CaO–SiO2–FeO and CaO–SiO2–MnO slags were carried out at 1,773 K on interstitial free (IF)-steel substrates using the sessile drop method. The composition of the slag was varied with amphoteric oxides of either FeO or MnO at unit basicity (C/S = 1.0). Results indicated a decrease in the interfacial tension with increased amphoteric oxide additions. The ionic species of molten slags were analyzed by FT-IR and the various types of oxygen ions (O2−, O−, O0) in the slag was determined by X-ray photoelectron spectroscopy. The silicate bonding degree and the slags ionic behavior were semi-quantitatively analyzed with respect to the slag’s ionic structure model. By dissociating the slags networking structure with increased free oxygen ions, the interfacial tension decreased. Considering the ionic theory of molten slags, results indicate that the interfacial properties are directly affected by the ionic structure of the slag. This work hopes to clarify the relationship between the interfacial tension and the distribution of various oxygen ions.

Experimental Investigations of Phase Equilibria of MnS Containing Sub-systems in the MnO–SiO2–Al2O3–MnS System

Phase equilibria of the MnO–MnS, MnO–SiO2–MnS, and MnO–Al2O3–MnS systems under low oxygen partial pressure have been experimentally investigated for the temperature range of 1200 to 1500°C using equilibration and quenching techniques. Equilibrium phases were analyzed by Scanning Electron Microscope, Electron Probe X-ray Microanalysis (EPMA), and Differential Thermal Analysis (DTA). Phase diagrams were successfully constructed for the systems investigated. A ternary compound in the MnO–SiO2–MnS system was observed at 1200°C and 1250°C. No ternary compound or solid solution was observed in the MnO–Al2O3–MnS system. The results of the present study were critically compared with the results reported previously.

Wetting of Solid Iron, Nickel and Platinum by Liquid MnO–SiO2 and CaO–Al2O3–SiO2

Wetting of solid metals―iron, nickel and platinum, by molten MnO-SiO 2 (MS) and CaO-Al 2 O 3 SiO 2 (CAS) oxide systems was studied by the sessile drop method at 1 350-1 450°C in reducing atmosphere. Terminal contact angles (after 240 min) for MS system were: for iron substrates-5±2 deg at 1 350°C, 9±2 deg at 1 390°C, 6±2 deg at 1450°C ; platinum-15±2 deg at 1 350°C and 1 390°C, and 12±2 deg at 1 450°C. Contact angle for the Ni-MS system was close to zero-3±2 deg at 1 350°C and 1 390°C. Contact angles with CAS system were: iron-55±2 deg (1 350°C), 60±2 deg (1 390°C), 44±2 deg (1 450°C); nickel-59±2 deg (1 350°C), 60±2 deg (1 390°C); and platinum-15±2 deg (1 350°C, 1 390°C and 1 450°C). Work of adhesion for all substrates with MS system was 910 to 930 mJ/m 2 . Interfacial tension with MS system was 1 480 mN/m for Ni at 1 350 to 1 390°C, and 1 880 to 1 890 mN/m for Pt in the temperature range 1 350 to 1 450°C. For iron, interfacial tension was 1 720 mN/m at 1 350°C; 1 580 mN/m at 1 390°C and 1 450°C. Lower work of adhesion and higher interfacial tension were found for metals with CAS system. Reduction of MnO from MS system was observed, leading to Mn dissolution in metal substrates. Degree of silica reduction from MS system was much smaller in comparison with MnO reduction (negligible for Pt); it was very minor from CAS system. Reduction of oxides and adsorption of oxygen modify the metal-oxide interface, making wetting dynamic and profoundly affecting interfacial properties.

Thermodynamics of Copper Dissolution into MnO–SiO2–MnS Inclusion System

Recently, a new process has been introduced to control α-γ transformation of steels using cuprous sulfide precipitates on the MnO bearing oxide inclusion as well as MnS. In order to optimize the composition of inclusions, the solubility of copper into MnO-SiO 2 -MnS system were measured at 1 523 K and a dissolution mechanism of copper into an oxy-sulfide melts and cuprous sulfide capacity has been proposed. The solubility of copper increased with an increase in MnO/(MnO+SiO 2 ) ratio and showed a maximum solubility at MnO and MnS doubly saturated composition, which was consistent with the maximum precipitation ratio of CuS. Deliberating an oxy-sulfide melts saturated with MnS, MnO, and SiO 2 at 1 523 K, the phase diagram for the MnO-SiO 2 -MnS system indicated that the activity coefficient of cuprous sulfide in an oxy-sulfide melts was dependent on the activity of MnO and the activity coefficient of MnS. The dissolution mechanism of copper into a MnO-MnS inclusion system was confirmed and cuprous sulfide capacity was also defined from the reaction mechanism. Cuprous sulfide capacity for the MnO-MnS bearing inclusion strongly depends on stability of sulfide and basicity. The experimental results revealed that the optimized composition for inclusion to dissolve copper was (mass%MnO)=43.6, (mass%SiO 2 )=1.8 and (mass%MnS)=54.6. Consequently, it could be proposed that the harmlessness of copper in scrap and dispersion strengthening could be possible by using the non-metallic inclusion technique.

磁気分離法による溶銑脱リンスラグからのリン回収法で生成する残渣スラグのリサイクル効果

The authors have found in their previous work that phosphorus exhibits remarkable segregations in the industrial hot metal pretreatment slag and it exists as Ca3P2O8–Ca2SiO4 solid solution together with FeO–CaO–SiO2–MnO–MgO matrix. Since their magnetic property of each phase is significantly different, it is possible to separate each phase with the aid of superconducting strong magnetic field. By applying strong magnetic field of 0.5 to 2.5 T to the crushed slag, more than 60% of phosphorus concentrated phase in the slag has been recovered. If the most of phosphorus can be removed from the slag, the residual slag is basically FeO–CaO–SiO2–MnO–MgO with less P2O5 and thus it may be recycled to iron and steelmaking processes such as the sintering, hot-metal desiliconization, and hot-metal dephosphorization processes. In the present work, the recycling effect of the residual slag to the dephosphorization process is simulated based on the mass balance calculation. The significant reduction of total slag generation and CaO input has been demonstrated by the mathematical model considering phosphorus recovery and recycling of residual slag as a dephosphorization agent. It has also been indicated by the Waste Input–Output model that the phosphorus recovery from dephosphorization slag and the recycling of residual slag to hot metal dephosphorization process have great environmental and economical benefits.

Production of Mn–Fe Alloy from Slag Generated in Mn-removal Treatment of Molten Cast Iron

Production of Fe–Mn alloy from the slag generated in the Mn-removal treatment of cast iron was investigated by using the method of carbon reduction of FeO–SiO2–MnO and FeO–SiO2–MnO–CaO slags at 1723 K.In the first stage, almost all the Fe was reduced from the slags, followed by the reduction of Si and Mn. Finally, Fe–Mn–Si metal was obtained as a result of the reduction treatment. The addition of CaO to the FeO–SiO2–MnO slag had two effects: (1) the slag viscosity decreased, thereby improving slag reactivity, and (2) the SiO2 activity in the slag melt decreased, thereby lowering the Si content in the metal. It was confirmed that the reaction between carbon and the slag is rate limiting reaction. The contact condition between the slag and carbon has a significant influence on the slag reactivity; improvement of the contact condition leads to an increase in the slag reactivity.

Thermodynamic Analysis of Selective Oxidation Behavior of Si and Mn-added Steel during Recrystallization Annealing

In order to establish the necessary conditions for producing high strength hot-dip Zn galvanized steel sheets for automotive use on a Continuous Galvanizing Line (CGL), a thermodynamic calculation of the selective oxidation behavior of Si, Mn-added high strength steel sheets was introduced, assuming a model in which an equilibrium is reached locally at the outermost surface layer of the steel sheet. The applicability of that model is confirmed by comparison with experimental results. Both the calculated chemical potential diagram for an Fe–Si–Mn–O system and an isothermal pseudo ternary phase diagram for an FeO–SiO2–MnO system, explain the reaction path of the selective oxidation behavior in 1 mass% Si and 0.01–3.01 mass% Mn-added steel. As this simulation model demonstrates good agreement with experimental results, this thermodynamic calculation is extremely appropriate for prediction of the surface oxidation behavior of Si, Mn-added high strength steel sheets. The transition from selective surface oxidation to internal oxidation can be explained by considering the oxygen flux in the oxidation film and the effect of the selective surface oxides on the inward diffusion behavior of oxygen. By thermodynamic calculation of the suppression condition of SiO2 film formation, which deteriorates the molten Zn wettability of the surface of annealed sheets, a process control model for industrially stable production of high strength hot-dip Zn galvanized steel sheets with arbitrary chemical compositions is proposed. Based on this research, a comprehensive surface control technology for high strength steel sheets is established.

Layered particles of zeotypes

The corrosion behavior of alumina-silica (Al2O3–SiO2) refractories by liquid carbon steel was studied. This was performed by a refractory crucible test in a vacuum induction furnace at 1520–1545 °C under reducing atmosphere. The results indicate that Mn, Si and a minor amount of Fe in the steel were oxidized at steel/refractory interface, combing with refractory components to form a MnO–SiO2–Al2O3–based slag. This slag was liquid at the testing temperature, and infiltrated along the open-pore network and the grain boundaries into the Al2O3–SiO2 refractories. Both Al2O3–rich and Al2O3–SiO2 aggregates in the refractories dissolved into the infiltrating slag. As a result, the refractories were structurally weakened and residual Al2O3–rich and Al2O3–SiO2 aggregates in the hot face of the refractories were washed away into the liquid steel, affecting steel quality.

Manganese Distribution Equilibrium between CaO–FetO–SiO2–MnO–P2O5–(Al2O3) Slags and Carbon Saturated Iron

In order to find out the optimum thermodynamic conditions for hot metal demanganization and predict the manganese content after demanganization pretreatment, the equilibrium experiments for the measurement of manganese distribution between CaO–FetO–SiO2–MnO–P2O5–(Al2O3) slags with silver were carried out in an iron crucible at 1573–1673 K under pure argon atmosphere. The manganese contents in silver were converted to that in the carbon-saturated iron using the known thermodynamic data. The distribution ratios between slags and carbon-saturated iron were calculated. The results indicate that manganese distribution ratios increase with a decrease in slag basicity, and they increase with an increase in FetO content in the slags at first, then they decrease with an increase in content of FetO. The maximum manganese distribution ratio is 576.6 with the FetO content of 50.30 mass% and the slag basicity of 0.27 at 1623 K, and the correspondent manganese content in the carbon saturated iron is 0.015 mass%. The manganese distribution ratios decrease with an increase in MnO content in the slags. On the other hand, Al2O3 content in the slag has little influence on the manganese distribution ratios. The equilibrium manganese distribution ratios obtained in the present work were summarized as a function of slag compositions and temperature by the multiple regression method.

Crystal Structure, Phase Relations and Electrochemical Properties of Monoclinic Li2MnSiO4.

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Obtaining a submerged arc welding flux of the MnO–SiO2–CaO–Al2O3 – CaF2 system by fusion

(2007). Obtaining a submerged arc welding flux of the MnO–SiO2–CaO–Al2O3 – CaF2 system by fusion. Welding International: Vol. 21, No. 7, pp. 502-511.

Crystal structure, phase relations and electrochemical properties of monoclinic Li 2MnSiO 4

Phase relations in the MnO–SiO 2–Li 4SiO 4 subsystem have been investigated by X-ray diffraction after solid-state reactions in hydrogen at 950–1150 °C. Both cation-deficient and cation-excess solid solutions Li 2+2 x Mn 1− x SiO 4 (−0.2⩽ x⩽0.2) based on Li 2MnSiO 4 have been found. According to Rietveld analysis, Li 2MnSiO 4 (monoclinic, P2 1/ n, a=6.3368(1), b=10.9146(2), c=5.0730(1) Å, β=90.987(1)°) is isostructural with γ II-Li 2ZnSiO 4 and low-temperature Li 2MgSiO 4. All components are in tetrahedral environment, (MnSiO 4) 2− framework is built of four-, six- and eight-member rings of tetrahedra. Testing Li 2MnSiO 4 in an electrochemical cell showed that only 4% Li could be extracted between 3.5 and 5 V against Li metal. These results are discussed in comparison with those for recently reported orthorhombic layered Li 2MnSiO 4 and other tetrahedral Li 2 MXO 4 phases.

Critical thermodynamic evaluation and optimization of the MnO–SiO 2–“ TiO 2 ”–“ Ti 2O 3 ” system

A complete review, critical evaluation, and thermodynamic optimization of phase equilibrium and thermodynamic properties of the MnO–SiO 2–“ TiO 2”–“ Ti 2O 3” systems at 1 bar pressure are presented. The molten oxide phase was described by the Modified Quasichemical Model. The Gibbs energies of the manganosite, spinel, pyrophanite and pseudobrookite and rutile solid solutions were taken from the previous study. A set of optimized model parameters for the molten oxide phase was obtained which reproduces all available reliable thermodynamic and phase equilibrium data within experimental error limits from 25 ∘C to above the liquidus temperatures over the entire range of compositions and oxygen partial pressure in the range of pO 2 from 10 −20 bar to 10 −7 bar. Complex phase relationships in these systems have been elucidated, and discrepancies among the data have been resolved. The database of model parameters can be used along with software for Gibbs energy minimization in order to calculate any phase diagram section or thermodynamic properties.

Effects of Dissolved Oxygen and Size Distribution on Particle Coarsening of Deoxidation Product

The growth mechanism for deoxidation products of MgO, ZrO2, Al2O3, CaO–Al2O3 and MnO–SiO2 in an Fe–10mass%Ni alloy has been studied under the condition of no fluid flow by considering the effects of dissolved oxygen and size distribution on Ostwald ripening. The coarsening rate of particles is largely dependent on the dissolved oxygen content. The spread of particle size distribution decreases in the order of Al2O3>ZrO2>MgO>CaO–Al2O3>MnO/SiO2 particles and that of solid Al2O3, ZrO2 and MgO particles becomes narrower with holding time. The coarsening rate is also affected by the spread of size distribution curve and this is the reason that the coarsening rate of Al2O3 particles is larger than that predicted from dissolved oxygen content.

Precipitation and Dispersion Control of MnS by Deoxidation Products of ZrO2, Al2O3, MgO and MnO–SiO2 Particles in Fe–10mass%Ni Alloy

An Fe–10 mass%Ni–1mass%Mn alloy was deoxidized with Zr, Al, Mg and Si and the effect of these deoxidation particles on MnS crystallization and/or precipitation has been studied as a function of S content with forcussing on the particle dispersion in microsegregation domain. MnS cannot be uniformly dispersed in microsegregtion domain since the crystallization and/or precipitation of MnS occur only on ZrO2 or Al2O3 particles located at the region of final solidification. MnS-containing MnO–SiO2 particles can be uniformly dispersed in microsegregation domain, if the S level is low enough for particles not to be pushed. MgS and/or (Mg, Mn)S crystallize on MgO particles in Mg deoxidation. In the case of high S level, the MgO, MgS/MgO and (Mg, Mn)S/MgO particles are pushed to the region of final solidification and then MnS crystallizes and/or precipitates on the pushed particles.

Characteristics of Particle Size Distribution of Deoxidation Products with Mg, Zr, Al, Ca, Si/Mn and Mg/Al in Fe-10mass%Ni Alloy

In the experiments of an Fe–10mass%Ni alloy deoxidized with Mg, Zr, Al, Ca, Mn/Si and Al/Mg at 1873 K, the characteristics of particle size distributions have been studied as a function of holding time, amount of deoxidant and order of deoxidant addition. The peak height in particle size distribution decreases and the modal value increases with increasing holding time. The width of the distribution curve is larger for Al2O3 particles and smaller for liquid CaO–Al2O3 and MnO–SiO2 particles. The number of particles increases with an increase of deoxidant for a given initial oxygen content and holding time. In the case of Al followed by Mg deoxidation, the particle size distribution is almost the same as that obtained by only Al. The size distribution in case of Mg followed by Al deoxidation is almost the same as that by only Mg.

Characteristics of Particle Size Distribution in Early Stage of Deoxidation

The spread of the size distributions obtained by deoxidizing an Fe–10mass%Ni alloy with Zr, Mg, Al, Ca and Si/Mn has been discussed with particular emphasis on the particle size distribution soon after the nucleation of deoxidation product. The geometric standard deviation in size distribution was found to be related to the interfacial energy between oxide and liquid Fe, γoxide–Fe(I). The nucleation rate decreases with an increase in γoxide–Fe(I) based on the homogeneous nucleation theory. Thus, the geometric standard deviation decreases with increasing the nucleation rate in which γoxide–Fe(I) is low such as the case of MnO–SiO2 particles. The experiment in which an Fe–10mass%Ni alloy was first deoxidized with Ti followed by Mg was carried out and narrow size distribution was obtained by separating the nucleation and growth processes.

Petrology and geochemistry of Early Tertiary volcanism of the Mendejin area, Iran, and implications for magma genesis and tectonomagmatic setting

The Mendejin area, NW Iran, is part of the western Alborz-Azarbaijan zone which is one of the most structurally—and magmatically-active zones of Iran. Volcanic rocks with calc-alkaline and, locally, alkaline features cover an extensive part of this zone. The Mendejin volcanic rocks, Eocene-Oligocene in age, include tuffs and volcanoclastic rocks of dacite, andesite, basaltic andesite, and basalt composition. Felsic (andesite, dacite, and rhyodacite) and basic rocks (basalt, basaltic andesite and andesite) commonly occur in successive layers. This alternation along with multiple occurrences of various types of tuffs suggests prolonged and successive magmatic activity during Eocene-Oligocene in NW Iran. Fractional crystallization has been the most important factor controlling geochemical characteristics of the magma. However, absence of linear correlations on variation diagrams of some immobile elements (such as Al2O3, TiO2, P2O5 and Ga) and poorly-developed trends on variation diagrams of Na2O, MgO, MnO, CaO, Fe2O3, Nb, Nd, Y, La, Ce, Th, Hf, Sc, Zn, V, Ni and Co versus SiO2 indicate that, other than crystal (olivine, pyroxene, plagioclase, biotite, hornblende, zircon, monazite and apatite) fractionation, crustal processes (such as assimilation) have also affected the chemistry of the Mendejin magma. It appears that the basic magma has originated from the mantle whereas the felsic magma resulted from modification in the mantle-derived magma by assimilation in an active continental margin.

Carbothermic reduction of pirolusite to obtain carbon-bearing ferromanganese and slag suited to the development of welding materials

Summary This article examines the process for obtaining high carbon ferromanganese by means of carbothermic reduction in a direct current electric arc furnace. It establishes the ideal composition of slag oxides to make a flux for use in submerged arc welding (SAW). The charge components (pirolusite, coke, steel wool, lime, rutile and fluorite) are calculated for a flux-free technology to obtain FeMn taking into account the characteristics of welding fluxes under the SiO2–MnO–CaO system. Reduction experiments are applied to the charge materials so as to obtain FeMn and slag, which are then used to develop an SAW flux.