Abstract During the high-temperature Bayer process, the inhibitory effect of titanium-containing minerals on diaspore digestion is believed to be resulted from the formation of a dense sodium titanate layer covering the diaspore particles, however, there is a lack of direct observational evidence to date. This work adopted X-ray photoelectron spectroscopy (XPS), cross-section SEM and in-situ analysis to clarify the inhibitory mechanism by investigating the interactions between Al-/Ti-/Si-bearing minerals in the simulated high-temperature Bayer digestion process. The observation of a sodium titanate layer provided direct evidence for the solid layer theory. XPS result further indicates that the Ti-O-Al bond is a significant factor in promoting the covering of sodium titanate on alumina-bearing mineral particles. Cross-section SEM and in-situ analyses illustrate that the dissolution of diaspore is carried out not only on the surface of diaspore particles but also on the inner surface such as pores and gaps of particles. Meanwhile, as similar to Ti-bearing minerals, the Si-bearing minerals also inhibit the diaspore digestion by forming a sodium aluminate silicate hydrate layer at an elevated temperature.

中文翻译：

---

高温拜耳消化中硬水铝石颗粒上钛酸钠和硅酸铝酸钠水合物层的观察

摘要 在高温拜耳法过程中，含钛矿物对水铝石消化的抑制作用被认为是由于在水铝石颗粒上形成了致密的钛酸钠层，但缺乏直接的观察证据。日期。本工作采用 X 射线光电子能谱 (XPS)、横截面 SEM 和原位分析，通过研究模拟高温拜耳消化过程中含铝/钛/硅矿物之间的相互作用来阐明抑制机制。 . 钛酸钠层的观察为固体层理论提供了直接证据。XPS 结果进一步表明，Ti-O-Al 键是促进钛酸钠在含氧化铝矿物颗粒上覆盖的重要因素。横截面扫描电镜和原位分析表明，硬水铝石的溶解不仅在硬水铝石颗粒的表面进行，而且在颗粒的孔隙和间隙等内表面进行。同时，与含钛矿物类似，含硅矿物也通过在高温下形成铝酸钠硅酸盐水合物层来抑制水铝石的消化。