高磷赤铁矿直接还原过程中CaO脱磷机制的分子动力学模拟

Molecular Dynamics Simulation of CaO Dephosphorization Mechanism during Direct Reduction of High-phosphorus Hematite

利用分子动力学模型(MD)模拟了在焙烧过程中(1150℃)不同用量CaO加入到Fe_(2)O_(3)-Ca_(5)(PO_(4))_(3)F-SiO_(2)三元体系后微观结构的变化规律,并借此阐明高磷赤铁矿直接还原过程中CaO的脱磷机制。分子动力学模拟和拉曼光谱分析结果表明,四元体系中的Si和P会形成四面体结构,体系中的非桥氧占主导地位。随着CaO添加量的增加,体系中Ca_(5)(PO_(4))_(3)结构更加稳定。体系中Si—O—Si为主的桥氧含量减少,复杂的[SiO_(4)]四面体减少,Si—O聚合体的聚集度降低。阐明了直接还原过程中CaO是通过解聚[SiO_(4)]四面体结构,减少了SiO_(2)与磷灰石的接触,从而抑制磷灰石还原达到脱磷效果的。

Using molecular dynamics(MD)simulation of Fe_(2)O_(3)-Ca_(5)(PO_(4))_(3)F-SiO_(2)-CaO microstructure changes of CaO on the compoment the quaternary system at roasting(1150℃),and clarify the mechanism of CaO in the process of direct reduction of dephosphorization.The results of molecular dynamics and Raman spectroscopy show that Si and P in the quaternary system will form a tetrahedral structure,with non-bridging oxygen dominating.With the increase of the amount of CaO,the structure of Ca_(5)(PO_(4))_(3) in the system is more stable.In the system,the Si—O—Si-based bridging oxygen content is reduced,the complex[SiO_(4)]tetrahedron is reduced,and the aggregation degree of the SiO_(2) polymer structure is reduced.It is clarified that CaO in the direct reduction process reduces the contact between SiO_(2) and apatite by depolymerizing[SiO_(4)]tetrahedral structure,thereby inhibiting the reduction of apatite to achieve the dephosphorization effect.