Alkali-activated Fe-rich non-ferrous metallurgical slag (AA-NFS), within the FeO-SiO-AlO-CaO-MgO system, were tested in 2 wt% sulfuric acid for 6 months. Corrosion depth and rate were measured non-destructively by micro X-ray computed tomography. Both intact and corroded areas were characterized by XRD, FTIR, SEM-EDX and NMR. AA-NFS with higher Ca/Si showed a higher resistance to sulfuric acid. The presence of Mg negatively affected the resistance, whereas higher Al concentrations slightly enhanced the resistance in the investigated chemical composition range. The corrosion degree is closely related to the NFS reaction extent in AA-NFS, and this corrosion process is diffusion-controlled. Leaching of the elements (Al, Ca, Mg, Fe and Na) leaves behind mostly silica-rich gels, causing the failure of the framework structure after long-term exposure. The leached Ca reacted with SO in acid solution and formed expansive sulfate products, which possibly clog pores and offer an additional protective barrier for AA-NFS against sulfuric acid.

中文翻译：

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碱激活富铁渣在硫酸中的降解


FeO-SiO-Al2O-CaO-MgO 系统中的碱激活富铁有色冶金渣 (AA-NFS) 在 2 wt% 硫酸中进行了 6 个月的测试。通过显微 X 射线计算机断层扫描无损测量腐蚀深度和速率。通过 XRD、FTIR、SEM-EDX 和 NMR 对完好区域和腐蚀区域进行了表征。具有较高 Ca/Si 的 AA-NFS 显示出较高的耐硫酸性。镁的存在会对电阻产生负面影响，而较高的铝浓度会稍微增强所研究的化学成分范围内的电阻。 AA-NFS中的腐蚀程度与NFS反应程度密切相关，且该腐蚀过程是扩散控制的。元素（铝、钙、镁、铁和钠）的浸出留下大部分富含二氧化硅的凝胶，导致长期暴露后框架结构失效。浸出的 Ca 在酸性溶液中与 SO 发生反应，形成膨胀的硫酸盐产物，这可能会堵塞孔隙，并为 AA-NFS 提供额外的针对硫酸的保护屏障。