Abstract

This paper investigated the oxidation of fayalite (Fe₂SiO₄) in iron-rich nickel slag (INS) for iron recycling via an oxidation-magnetic separation method. A phase stability diagram of the FeO–SiO₂–MgO–CaO–O₂ system drawn by FactSage 7.1 illustrates that magnetite (Fe₃O₄) can be crystallized from liquid slag in an air atmosphere, but the further oxidation to Fe₂O₃ in molten slag was extremely hard. The mass content of divalent iron (w(Fe²⁺)) decreased and the ratio of trivalent iron to divalent iron (w(Fe³⁺)/w(Fe²⁺)) increased gradually with increasing oxidation time. The results show that an air flow rate of 300–500 mL/min, a basicity of 0.90–1.10, and a temperature of 1658–1728 K are conducive to the oxidation of Fe₂SiO₄ in INS. Fe₃O₄ is the main iron-bearing phase, and Fe₂O₃ is not observed in the X-ray diffraction (XRD) patterns. Silicates in the oxidized nickel slag (ONS) are mainly augite (Ca(Mg,Fe)Si₂O₆), forsterite ((Mg,Fe)₂SiO₄), and monticellite (CaMgSiO₄), while akermanite (Ca₂MgSi₂O₇) is observed only for a basicity up to 1.10. The oxidation kinetics of Fe₂SiO₄ in INS are first order with an apparent activation energy (E_a) of 315.16 kJ/mol.

中文翻译：

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铁镍矿在熔融镍渣中的氧化

摘要

本文通过氧化-磁分离法研究了富铁镍渣（INS）中铁橄榄石（Fe ₂ SiO ₄）的氧化过程，以循环利用铁。由FactSage 7.1绘制的FeO–SiO ₂ –MgO–CaO–O ₂系统的相稳定性图说明，磁铁矿（Fe ₃ O ₄）可以在空气中从液态炉渣中结晶出来，但会进一步氧化成Fe ₂ O ₃在熔渣中非常坚硬。二价铁（w（Fe ²⁺））的质量含量降低，三价铁与二价铁的比例（w（Fe ³⁺）/ w（Fe ²⁺））随着氧化时间的增加而逐渐增加。结果表明，空气流速为300–500 mL / min，碱度为0.90–1.10，温度为1658–1728 K有助于INS中Fe ₂ SiO ₄的氧化。Fe ₃ O ₄是主要的含铁相，在X射线衍射（XRD）图中未观察到Fe ₂ O ₃。氧化镍渣（ONS）中的硅酸盐主要是钠铁矿（Ca（Mg，Fe）Si ₂ O ₆），镁橄榄石（（Mg，Fe）₂ SiO ₄）和蒙脱石（CaMgSiO ₄），而钙钛矿（Ca ₂ MgSi ₂仅在不超过1.10的碱度下才能观察到O ₇）。在INS中Fe ₂ SiO ₄的氧化动力学是一级的，表观活化能（E _a）为315.16 kJ / mol。