本研究探討在各種不同氣氛環境下，球結礦的還原行為，目的是改善富氫高爐煉鐵製程。實驗採用不同的 H2-CO 混合氣體比例，並在多種溫度條件下進行還原試驗。透過熱重分析 (TGA) 測量還原程度，並利用質譜儀 (mass spectrometry) 定量分析 CO 與 H2 各自的還原貢獻。
此外，採用同步輻射 X 光繞射 (XRD) 進行相組成分析，並透過掃描式電子顯微鏡(SEM) 進行橫截面觀察，以更深入了解氣氛組成與溫度的影響。結果顯示，球結礦中存在明顯的「殼-核結構」，並因為球結礦內外之還原不均勻性 (reduction non-homogeneity)，促使相反方向的內部應力生成，使緻密層出現。例如CO:H2比例為3:1，在700-900℃持溫120分鐘時，在試片橫截面會出現大約13%面積比例的緻密層，形成獨特的形貌特徵。
另外，利用還原率之結果觀察到，當使用混合氣氛時，CO和H2之還原會出現協同效應 (synergy effects)，使還原效率高於預期。例如當CO:H2比例為3:1，在700℃持溫120分鐘時，實驗結果比用單一氣氛之結果依氣氛比例計算之結果，還原率提升13.8%。此現象可歸因於氫氣優異的擴散能力，導致CO和H2能在球結礦中合作進行還原反應。
本研究為優化氫氣利用策略，利用以上成果來優化富氫條件下的高爐煉鐵殼核模型，以應用於現代高爐煉鐵製程，提供重要的數據基礎。

This study investigates the reduction behavior of iron ore pellets under various gas atmospheres, aiming to improve the hydrogen-rich blast furnace ironmaking process. A series of reduction experiments were conducted using different H2-CO gas ratios at multiple temperatures. The reduction degree was measured using thermogravimetric analysis (TGA), and the individual reduction contributions of CO and H2 were quantitatively analyzed via mass spectrometry.
In addition, synchrotron X-ray diffraction (XRD) was employed for phase composition analysis, and scanning electron microscopy (SEM) was used for cross-sectional observations to gain deeper insight into the effects of gas composition and temperature. The results revealed a distinct “core-shell structure” within the pellets. Furthermore, reduction non-homogeneity between the pellet’s shell and core generated opposing internal stresses, leading to the formation of a dense layer. For example, under a CO:H2 ratio of 3:1 at 700-900°C with isothermal for 120 minutes, a dense layer covering approximately 13% of the cross-sectional area was observed, creating a unique morphological feature.
Analysis of the reduction degree results further showed that mixed-gas atmospheres exhibited a synergy effect between CO and H2, yielding a greater reduction efficiency than anticipated. For instance, at a CO:H2 ratio of 3:1 and 700°C with a holding time of 120 min, the experimental reduction rate was 13.8% higher than the calculated value from single-gas data. This phenomenon is attributed to the superior diffusivity of hydrogen, enabling CO and H2 to cooperate in the reduction reaction within the pellet.
Based on these findings, this study provides a foundation for optimizing the core-shell model of hydrogen-rich blast furnace ironmaking under high hydrogen conditions, thereby offering essential data for modern blast furnace process optimization.

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