Calcium silicate is the undesirable bonding phase in sinter with relatively high melting point and poor reducibility, while the formation mechanism in sinter is ambiguous. Herein, the phase transformation, phase quantification, and morphology evolution of calcium silicate and calcium ferrite in CaO‐SiO2‐Fe2O3‐Al2O3 systems under different n(Fe2O3)/n(CaO) and Al2O3 content are investigated. It is found that with the increase of n(Fe2O3)/n(CaO), the calcium ferrite phases transform from Ca2Fe2O5 (C2F) to complex calcium ferrite, and calcium silicate phases including β‐Ca2SiO4 (β‐C2S) and γ‐Ca2SiO4 (γ‐C2S) are promoted. Moreover, small amount (2%) of Al2O3 can effectively promote the content of silico‐ferrite of calcium and aluminum (SFCA) increasing from 20.95% to 46.69%, whereas inhibiting the β‐C2S from 51.79% to 42.34%. When the content of Al2O3 is over 4%, the Ca2Al(AlSiO7) phase is formed, where both the SFCA and calcium silicate are inhibited. On this base, the competitive mechanism for the formation of calcium silicate and calcium ferrite is revealed, where the Ca2+ and Si4+ are preferred to react with Fe3+ and Al3+ to form liquid phase SFCA, while the amount for β‐C2S or γ‐C2S can be decreased due to the deprivation of Ca2+ and Si4+.

中文翻译：

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铁矿粉烧结过程中硅酸钙和铁酸钙的竞争形成行为

硅酸钙是烧结矿中的不良粘结相，熔点较高，还原性较差，但其在烧结矿中的形成机制尚不明确。本文研究了 CaO-SiO 中硅酸钙和铁酸钙的相变、相定量和形态演化2‐铁2氧3‐铝2氧3不同n(Fe2氧3)/n(CaO) 和 Al2氧3内容进行调查。发现随着n(Fe2氧3)/n(CaO)，铁酸钙相由 Ca 转变而来2铁2氧5（C2F) 形成复合铁酸钙和硅酸钙相，包括 β-Ca2二氧化硅4(β-C2S) 和 γ-Ca2二氧化硅4(γ-C2S) 得到提升。此外，少量（2%）的Al2氧3能有效促进钙铝硅铁氧体（SFCA）含量从20.95%增加到46.69%，同时抑制β-C2S从51.79%增加到42.34%。当Al含量2氧3超过 4% 时，Ca2铝(AlSiO7) 相形成，其中 SFCA 和硅酸钙均受到抑制。在此基础上，揭示了硅酸钙和铁酸钙形成的竞争机制，其中Ca2+和硅4+优选与Fe反应3+和艾尔3+形成液相SFCA，而β-C的量2S或γ-C2由于Ca的缺乏，S会减少2+和硅4+。