Experimental Study of Ferrous Calcium Silicate Slags: Phase Equilibria at {\text{P}}_{{{\text{O}}_{2} }} Between 10–8?atm and 10–9?atm

The phase equilibria of ferrous calcium silicate slags (“FeO _x ”-CaO-SiO₂) have been investigated at an oxygen partial pressure of 10^–8 atm at temperatures between 1423 K and 1623 K (1150 °C and 1350 °C), and at an oxygen partial pressure of 10^–9 atm at temperatures of 1473 K and 1573 K (1200 °C and 1300 °C). High-temperature equilibration/quenching/electron probe X-ray microanalysis (EPMA) techniques were applied to acquire accurate information on the phase equilibria of the system. Phase diagrams showing the liquidus isotherms of the systems at the selected oxygen partial pressures are provided. The solubilities of components in the solids of primary phases are presented. The system and conditions selected are relevant to industrial copper smelting.     

Phase Equilibria of “Cu2O”-“FeO”-CaO-MgO-Al2O3 Slags at PO2 of 10-8.5 atm in Equilibrium with Metallic Copper for a Copper Slag Cleaning Production

Limited data are available on phase equilibria of the multicomponent slag system at the oxygen partial pressures used in the copper smelting, converting, and slag-cleaning processes. Recently, experimental procedures have been developed and have been applied successfully to characterize several complex industrial slags. The experimental procedures involve high-temperature equilibration on a substrate and quenching followed by electron probe X-ray microanalysis. This technique has been used to construct the liquidus for the “Cu₂O”-“FeO”-SiO₂-based slags with 2 wt pct of CaO, 0.5 wt pct of MgO, and 4.0 wt pct of Al₂O₃ at controlled oxygen partial pressures in equilibrium with metallic copper. The selected ranges of compositions and temperatures are directly relevant to the copper slag-cleaning processes. The new experimental equilibrium results are presented in the form of ternary sections and as a liquidus temperature vs Fe/SiO₂ weight ratio diagram. The experimental results are compared with the FactSage thermodynamic model calculations.     

Distribution of Calcium and Aluminum Between Molten Silicon and Silica-Rich CaO-Al2O3-SiO2 Slags at 1823 K (1550 °C)

Metallurgical and Materials Transactions B - Oxidative refining of silicon after tapping from the furnace is performed to remove calcium and aluminum impurities. Depending on the slag composition,...     

Phase Relationship of CaO-SiO2-FeO-5 mass pct P2O5 System with Low Oxygen Partial Pressure at 1673?K (1400?°C)

Dephosphorization by using multiphase flux could considerably decrease the consumption of CaO and prevent the addition of fluorite. However, the equilibrium phase relationship within this system, which is of significant importance for understanding the formation mechanism of multiphase flux, remains unclear. Thus, it is required to provide reliable phase diagrams of the basic slag system of multiphase flux. In this research, the phase relationship of the CaO-SiO₂-FeO-5 mass pct P₂O₅ system at 1673?K (1400?°C) with $ {P}_{{{\text{O}}_{2} }} $ of 9.24?×?10^?11 atm has been studied by using the chemical equilibration method. It has been found that solid solution consists mainly of 2CaO·SiO₂-3CaO·P₂O₅, but occasionally it contains 3CaO·SiO₂. Liquidus saturated with solid solution shrinks toward the FeO corner compared with the isothermal at 1673?K (1400?°C) of the CaO-SiO₂-FeO system equilibrated with metallic iron. Thermodynamically stable CaO-FeO phase is confirmed, which could promote the condensation of 3CaO·P₂O₅ into the solid solution and increase the phosphorus partition ratio between the solid solution and molten slag. Based on the regular solution model, the effect of T.Fe and CaO content in the liquid phase on the phosphorus partition ratio between the solid solution and molten slag is discussed.     

Investigation of Liquidus Temperatures and Phase Equilibria of Copper Smelting Slags in the FeO-Fe2O3-SiO2-CaO-MgO-Al2O3 System at PO2 10?8?atm

Copper concentrates and fluxes can contain variable levels of SiO₂, CaO, and MgO in addition to main components Cu, Fe, and S. Metal recovery, slag tapping, and furnace wall integrity all are dependent on phase equilibria and other properties of the phases and are functions of slag composition and operational temperature. Optimal control of the slag chemistry in the copper smelting, therefore, is essential for high recovery and productivity; this, in turn, requires detailed knowledge of the slag phase equilibria. The present work provides new phase equilibrium experimental data in the FeO-Fe₂O₃-SiO₂-CaO-MgO-Al₂O₃ system at oxygen partial pressure of 10⁻⁸ atm within the range of temperatures and compositions directly relevant to copper smelting. For the range of conditions relevant to the Kennecott Utah Copper (South Magna, UT) smelting furnace, it was confirmed experimentally that increasing concentrations of MgO or CaO resulted in significant decreases of the tridymite liquidus temperature and in changes in the position of the tridymite liquidus in the direction of higher silica concentration; in contrast, the spinel liquidus temperatures increase significantly with the increase of MgO or CaO. Olivine and clinopyroxene precipitates appeared at high MgO concentrations in the liquid slag. The liquidus temperature in the spinel primary phase field was expressed as a linear function of 1/(wt pctFe/wt pctSiO₂), wt pctCaO, wt pctMgO, and wt pctAl₂O₃. The positions of each of the liquidus points (wt pctFe)/(wt pctSiO₂) at a fixed temperatures in the tridymite primary phase field were expressed as linear functions of wt pctCaO, wt pctMgO, and wt pctAl₂O₃.     

Syntheses and Structures of Two Heteronuclear Complexes with Glycine {[CuEr(Gly)_5(H_2O)_2](ClO_4)_5·H_2O}_n and {[Cu_2Gd_2(Gly)_10 (H_2O)_4](ClO_4)_10·4H_2O}_n

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Effect of Cobalt on Phase Formation, Microstructure, and Mechanical Properties of Cu50?xCoxZr50 (x?=?2, 5, 10, 20?at.?pct) Alloys

In this work, the effect of cobalt on the phase formation and mechanical properties of rapidly solidified Cu_50?xCo_xZr₅₀ (x?=?2, 5, 10, and 20?at.?pct) alloys was investigated. CuZr martensite forms in the case of low Co contents (x?=?2 and 5?at.?pct), while in the alloys with 10 and 20?at.?pct Co, the B2 phase is stable even at room temperature. The deformation behavior of the rods under compressive loading depends strongly on the microstructure and, thus, on the alloy composition. Cobalt affects the fracture strength of the as-cast samples, and deformation is accompanied by two yield stresses for high Co-content alloys, which undergo deformation-induced martensitic transformation.     

Experimental Investigation of Gas/Slag/Matte/Spinel Equilibria in the Cu-Fe-O-S-Si System at 1473 K (1200 °C) and P(SO2) = 0.25 atm

Metallurgical and Materials Transactions B - New experimental data were obtained on the gas/slag/matte/spinel equilibria in the Cu-Fe-O-S-Si system at 1473 K (1200 °C) and...     

Experimental Investigation of Gas/Slag/Matte/Tridymite Equilibria in the Cu-Fe-O-S-Si System in Controlled Gas Atmosphere: Experimental Results at 1523 K (1250 °C) and <Emphasis Type="Italic">P</Emphasis>(SO<Subscript>2</Subscript>) = 0.25 atm

To assist in the optimization of copper smelting and converting processes, accurate new measurements of the phase equilibria of the Cu-Fe-O-S-Si system have been undertaken. The experimental investigation was focused on the characterization of gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si system at 1523 K (1250 °C), P(SO₂) = 0.25 atm, and a range of P(O₂)s. The experimental methodology, developed in PYROSEARCH, includes high-temperature equilibration of samples on substrate made from the silica primary phase in controlled gas atmospheres (CO/CO₂/SO₂/Ar) followed by rapid quenching of the equilibrium condensed phases and direct measurement of the phase compositions with electron-probe X-ray microanalysis (EPMA). The data provided in the present study at 1523 K (1250 °C) and the previous study by the authors at 1473 K (1200 °C) has enabled the determination of the effects of temperature on the phase equilibria of the multicomponent multiphase system, including such characteristics as the chemically dissolved copper in slag and Fe/SiO₂ ratio at silica saturation as a function of copper concentration in matte. The new data will be used in the optimization of the thermodynamic database for the copper-containing systems.     

Experimental Investigation of Gas/Slag/Matte/Tridymite Equilibria in the Cu-Fe-O-S-Si System in Controlled Gas Atmospheres: Experimental Results at 1473 K (1200 °C) and <Emphasis Type="Italic">P</Emphasis>(SO<Subscript>2</Subscript>) = 0.25 atm

Experimental studies were undertaken to determine the gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si system at 1473 K (1200 °C), P(SO₂) = 0.25 atm, and a range of P(O₂)’s. The experimental methodology involved high-temperature equilibration using a substrate support technique in controlled gas atmospheres (CO/CO₂/SO₂/Ar), rapid quenching of equilibrium phases, followed by direct measurement of the chemical compositions of the phases with Electron Probe X-ray Microanalysis (EPMA). The experimental data for slag and matte were presented as a function of copper concentration in matte (matte grade). The data provided are essential for the evaluation of the effect of oxygen potential under controlled atmosphere on the matte grade, liquidus composition of slag and chemically dissolved copper in slag. The new data provide important accurate and reliable quantitative foundation for improvement of the thermodynamic databases for copper-containing systems.     

Role of Ti on Phase Evolution,Oxidation and Nitridation of Co–30Ni–10Al–8Cr–5Mo–2Nb–(0, 2 & 4) Ti Cobalt Base Superalloys at Elevated Temperature

Titanium is an important alloying addition to γ/γ′ cobalt-based superalloys that enhances the high temperature microstructural stability and make the alloys lighter. In this work, we probe the role of Ti composition on the phase stability and oxidation behavior of Co–30Ni–10Al–8Cr–5Mo–2Nb superalloys. With Ti addition, the γ′-solvus temperature is enhanced and the γ′-precipitate shape changes from spherical to rounded cuboids. Addition of 4 at. pct Ti to the alloy promotes topologically-close-packed (TCP) phase formation that are rich in Co, Cr, and Mo. During oxidation at 900 °C, Ti was found to facilitate the early formation of passivating oxide layers (spinel CoCr₂O₄/CoAl₂O₄) on the exposed surfaces, however, it was not effective in reducing the oxidation-induced mass gain. Microstructural analysis reveals that Ti delays the Al₂O₃ layer formation eventually leading to faster oxidation kinetics. Additionally, we also found formation of (Ti,Nb)N in the γ′ denuded zones near the alloy-oxide interface.