Copper slag, which contains Fe-rich fayalite (Fe₂SiO₄), is a valuable solid waste that warrants further research in order to recover iron. Calcium oxide (CaO) can significantly enhance iron recovery from copper slag; however, the associated mechanism has not yet been explored. In this study, we investigated the interaction between CaO and Fe₂SiO₄ to obtain detailed understanding of the role of CaO in enhancing iron recovery. The presence of CaO was found to accelerate the decomposition of Fe₂SiO₄ via an ion-exchange-like process. Specifically, CaO dissociated into Ca(II) and a Ca-deficient Ca_1-yO species at high temperatures. The Fe(II) ion at the M2 site of Fe₂SiO₄ was substituted by the released Ca(II) ion, resulting in the formation of [(Fe_(2-x)Ca_x)SiO₄]∙xFe(II). Subsequently, the substituted Fe(II) occupied the Ca vacancy in Ca_1-yO to form (Ca_(1-y)Fe(II)_y)O. The disproportionation of Fe(II) and the combination reaction between CaO and the SiO₂ separated from Fe₂SiO₄ led to the generation of the final products, viz. Fe₂O₃, Fe₃O₄, and CaSiO₃. This study explains the specific role of CaO in decomposing Fe₂SiO₄. This would not only provide theoretical guidance for iron recovery from copper slag but also present a new perspective on the recycling of valuable resources from many other smelting slags (e.g., iron slag, lead slag, and nickel slag).

铜渣中含有富铁的铁橄榄石（Fe ₂ SiO ₄），是一种有价值的固体废物，需要进一步研究以回收铁。氧化钙（CaO）可以显着提高铜渣中铁的回收率；但是，尚未探索相关的机制。在这项研究中，我们调查了CaO和Fe ₂ SiO ₄之间的相互作用，以详细了解CaO在促进铁回收中的作用。发现CaO的存在通过类似离子交换的过程加速了Fe ₂ SiO ₄的分解。具体来说，CaO分解为Ca（II）和缺钙的Ca ₁ - _y高温下的O类。Fe ₂ SiO ₄的M2位处的Fe（II）离子被释放的Ca（II）离子取代，从而形成[（Fe _{（2- x）} Ca _x）SiO ₄ ]∙ x Fe（II ）。随后，取代的Fe（II）在Ca _{1- y} O中占据Ca空位，形成（Ca _{（1- y）} Fe（II）_y）O。Fe（II）的歧化以及CaO与从Fe ₂ SiO _4中分离出的SiO ₂的组合反应导致最终产物的生成，即。铁₂ O₃，Fe ₃ O ₄和CaSiO ₃。这项研究解释了CaO在分解Fe ₂ SiO _4中的特定作用。这不仅将为从铜渣中回收铁提供理论指导，而且还将为从许多其他冶炼渣（例如铁渣，铅渣和镍渣）中回收宝贵资源提供新的视角。