Katsunori Yamaguchi

Heat content and heat of formation measurements of RNi5 ± x alloys (R ≡ La, Ce, Pr or Nd) and heat balance in a reduction-diffusion process

Abstract The heat contents of the LaNi 5.25 , CeNi 5.13 , PrNi 4.65 and NdNi 5.85 alloys were measured over the temperature range 800–1400 K using a drop calorimeter. The heat content and heat capacity equations were derived using the Shomate function. The heats of formation of these alloys were determined at 773 K from the heats of dissolution of these compounds and their components in a liquid tin solvent using a Calvet-type solution calorimeter. Heat balance was calculated for a reduction-diffusion process to make the RNi 5 powders directly for use as hydrogen storage media by reducing the rare earth resources with metallic calcium, magnesium and lithium.

Liquidus relationships of calcium ferrite and ferrous calcium silicate slag in continuous copper converting

Abstract While calcium ferrite slags have been successfully used in continuous copper converting for the past 30 years, ferrous calcium silicate slag was proposed ∼8 years ago as an additional alternative for copper smelting. Although these slags are normal extensions of each other, their phase relations have not been completely clarified. In this paper, liquidus relations for both slags have been quantified in some regions of common composition. Existing experimental data are reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx–SiO2–CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO, as well as Fe/CaO versus temperature and Fe/SiO2 versus temperature are proven much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams, the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Fe/CaO versus Cu2O and Fe/SiO2 versus CaO relationships at various copper contents are predicted. The results show good agreement with the experimental data. It is also shown that, in the presence of liquid copper, Cu2O is dissolved in the slag to an extent depending on the oxidation degree of the system, which may lower the liquidus temperature. Discussions are presented taking into account plant observations, and important conclusions are drawn for copper smelting and converting.

Influence of Partial Pressure of Sulfur and Oxygen on Distribution of Fe and Mn between Liquid Fe-Mn Oxysulfide and Molten Slag

The authors proposed an innovative process for recovering Mn from steelmaking slag. The process starts with the sulfurization of steelmaking slag to separate P from Mn by the formation of a liquid sulfide phase (matte). Then, the obtained matte is weakly oxidized to make a Mn-rich oxide phase without P. High-purity Fe-Mn alloys can therefore be produced by the reduction of the Mn-rich oxide phase. However, to the authors’ knowledge, the sulfurization of molten slag containing P and Mn has not been sufficiently investigated. It was recently found that P was not distributed to the matte in equilibrium with the molten slag. To gain knowledge of the process’s development, it is important to investigate the influence of the partial pressures of sulfur and oxygen on the equilibrium distribution of Mn and Fe between the matte and the molten slag. In the current work, a mineralogical microstructure analysis of the matte revealed that the existence of the oxysulfide and metal phases was dependent on the partial pressure of sulfur and oxygen. The Mn content of the matte increased with partial pressure of sulfur while the O content of the matte decreased. In contrast, the ratio of Mn/Fe in the matte was constant when the metal phase of the matte was observed at a log

Lead Solubility in FeOx-CaO-SiO2-NaO0:5 and FeOx-CaO-SiO2-CrO1:5 Slags under Iron Saturation at 1573 K

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High temperature enthalpy measurement of SUS340 stainless steel

below −11. These results also corresponded to the relationship between the activity coefficient ratio of MnS/FeS and the mole fraction of MnS/FeS in the matte. The γMnS/γFeS value decreased exponentially as the mole fraction of MnS/FeS increased.

Formation of CaSO4 in the CaO-FeOx-Cu2O Slags

We propose a novel process to recycle Mn from steelmaking slag. The first step is to sulfurize the slag, producing a liquid sulfide phase (matte) without P. High-purity Fe-Mn alloys can then be made by desulfurizing the matte. However, to our knowledge, there have been no reports to date concerning the sulfurization of P and Mn contained in molten slag. Therefore, knowledge of the distribution of Fe, Mn and P between the matte and the molten slag is required to determine the feasibility of this process. In this study, the equilibrium distributions of Mn, Fe, Ca and P between a FeS-MnS matte and FeO-MnO-SiO2-MgO-P2O5 slag with/without CaO are investigated under controlled partial pressures of oxygen and sulfur. It was found, as P is not present in the matte, that a separation of P from Mn was accomplished. The increament of (CaOCMgO)=SiO2 in slag can improve the concentrations of Mn and Fe in the matte. The content of Ca in the matte was less than 2 mass%, even when the concentration ratio of CaO=SiO2 in the slag was unity.

Thermodynamic investigation of the Cu-Zr system

The sodium and chromium contents in copper or lead smelting slags are increasing with the increase in waste recycling. The lead solubility in the slag is important from both an economical and environmental perspective. As a fundamental study, experiments have been carried out to determine the equilibria between the FeOx-CaO-SiO25mass%NaO0:5 or FeOx-CaO-SiO2-5mass%CrO1:5 slags and lead metal in iron crucibles at 1573 K. It has been found that addition of soda decreases the lead solubility in SiO2 rich side of the slag, while soda increases the solubility in CaO rich side. Chromium in the slag decreases the lead solubility in the FeOx-CaO-SiO2 slag. The activity coefficients of PbO in the FeOx-CaO-SiO2-5mass%NaO0:5 or FeOx-CaO-SiO2-5mass%CrO1:5 slags were compared with those of the CaO-SiO2-FeOx ternary system.

Lead solubility in FeOx-CaO-SiO2 slags at iron saturation

Abstract In our previous paper, a slag modification process involving the mixing of stainless steelmaking and nonferrous smelting slags was proposed for preventing the disintegration of the stainless steelmaking slag. In order to use this method, the behavior of heavy metals especially PbO contained in the nonferrous slag has to be assessed. In the present study, the activity coefficient of PbO in CaO-SiO2-FetO-Al2O3-MgO and CaO-SiO2-FetO slags saturated with iron was measured at 1673 K. The results showed that the activity coefficient of PbO increased with basicity and had a maximum value when the basicity was approximately 1.0. The equilibrium PbO content in the modified slag had a minimum value that corresponded to a mixing ratio of 0.6. The trend was similar to the change in the removal ratio of PbO observed in the previous study. Therefore, the change in the oxygen potential and the change in the activity coefficient of PbO can be considered the cause of this trend.