This study investigated the aqueous carbonation mechanisms of three typical steel slags: ladle metallurgy furnace (LMF) slag containing high Al content, electric arc furnace (EAF) slag featuring high Si content and relatively low Al content, and ladle-arc fusion (LAF) slag with medium-Al content. It was found that the carbonation kinetics of the three slags were similar and followed the surface coverage model within the first 6 h of carbonation. Initially, the carbonation process was primarily governed by the reaction product precipitation. After 3 h of carbonation, the process was dominated by mineral dissolution, controlled by the uncovered reactive sites. The carbonation-reactive Ca-bearing minerals in the slags, including silicates (CRSis) and aluminates (CRAls), sequestered CO2 to form calcite during carbonation, accompanied by the formation of silica gel and alumina gel, respectively. CRSi, mainly larnite, was present in EAF and LAF slags, showing high reactivity, whereas mayenite (i.e., C12A7), a CRAl mineral present across all slags, exhibited high reactivity in LMF slag but lower reactivity in EAF and LAF slags. Furthermore, AFm phases and katoite (i.e., C3AH6) were detected in LMF slag as CRAls along with mayenite, and their carbonation reactivity decreased in the order of AFm>mayenite>katoite. As a result, low-Al steel slag tends to have higher carbonation reactivity, as manifested by the high carbonation degree of EAF slag throughout the reaction period, notably achieving a 40 % carbonation degree within 30 min and 71 % after 24 h under the studied conditions.

中文翻译：

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钢渣水溶液碳化作用机理的比较研究


本研究研究了 3 种典型钢渣的水碳化机理：高 Al 含量的钢包冶金炉 （LMF） 渣、Si 含量高但 Al 含量相对较低的电弧炉 （EAF） 渣和中 Al 含量的钢包电弧熔融 （LAF） 渣。结果表明，3 种炉渣的碳化动力学相似，并且在碳化前 6 h 内遵循表面覆盖模型。最初，碳酸化过程主要由反应产物沉淀控制。碳化 3 小时后，该过程以矿物溶解为主，由未覆盖的反应性位点控制。炉渣中的碳化反应性含钙矿物，包括硅酸盐 （CRSis） 和铝酸盐 （CRAls），在碳化过程中封存 CO2 形成方解石，并分别形成硅胶和氧化铝凝胶。CRSi，主要是拉尔石，存在于电弧炉和LAF炉渣中，表现出高反应性，而Mayenite（即C12A7）是一种存在于所有炉渣中的CRAl矿物，在LMF炉渣中表现出高反应性，但在电弧炉和LAF炉渣中表现出较低的反应性。此外，在 LMF 渣中检测到 AFm 相和 katoite （即 C3AH6） 作为 CRAls 与白云石一起，它们的碳化反应性以 AFm>mayenite>katoite 的顺序降低。因此，低铝钢渣往往具有较高的碳化反应性，表现为电弧炉渣在整个反应过程中的高碳化度，特别是在研究条件下，30 min 内达到 40 % 的碳化度，24 h 后达到 71 %。