ニッケル合金とFeO_x-MgO-SiO_2系ないしはFeO_x-CaO-MgO-SiO_2系スラグ間の相平衡 [in Japanese] Phase Equilibrium between FeO_x-MgO-SiO_2 or FeO_x-CaO-MgO-SiO_2 Slag and Nickel Alloy [in Japanese]
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The phase equilibrium between the MgO saturated FeOx-MgO-SiO2 slag and Ni-Fe alloy was investigated in the oxygen pressure region from 3 × 10-5 and 3 × 10-2 Pa at 1,673, 1,773 and 1,873 K to analyze the nickel smelting processes. The effect of CaO addition on the phase relation between the same slag system and Ni-Fe or Ni-Cu-Fe alloy were also studied at 1,673 and 1,773 K. The following experimental results have been obtained in the present study. The MgO solubility in the FeOx-SiO2 slag decreases with decreasing SiO2 content and temperature and also by the addition of CaO. However, there is no significant difference between the MgO solubilities in the slag equilibrating with the Ni-Fe or Ni-Cu-Fe alloy. The distribution ratios of nickel and iron between the MgO saturated FeOx-MgO-SiO2 slag and Ni-Fe alloy phases at log pO2 = -8 and 1,773 K are almost 0.01 and 1, respectively. These values increase with increasing the oxygen pressure and decreasing temperature. These indicate that nickel condenses mainly in the metal phase while iron is distributed in both the slag and metal phases. The CaO addition to the MgO saturated slag depresses the distribution ratios of nickel and iron in the slag phase. Comparing the distribution ratio of nickel equilibrating with the Ni-Fe or Ni-Cu-Fe alloy system, the increase of nickel dissolution in the slag equilibrating with the metal phase containing copper is mainly attributed to the change in the activity coefficient of nickel in the alloy phase. The values of 3 and 7 are estimated as the activity coefficients of NiO(s) and CuO0.5(l) in the MgO saturated FeOx-MgO-SiO2 slag at 1,773 K. The activity coefficient values increase with the addition of CaO in the slag. Thus, the dissolution of nickel and copper in the slag has been thermodynamically evaluated to decrease with CaO addition.
- Journal of MMIJ
Journal of MMIJ 114(2), 127-132, 1998-02-25
The Mining and Materials Processing Institute of Japan