Northeastern University, Shenyang, 110819, China.
Environ Sci Pollut Res Int. 2022 Oct;29(48):73326-73340. doi: 10.1007/s11356-022-20964-x. Epub 2022 May 27.
The main chemical component of high-silicon iron tailings (HSITs) is SiO; HSITs also include some oxides such as AlO and CaO. Mechanical activation can reduce the particle size of HSITs and enhance their pozzolanic activity such that they can be used as a type of mineral admixture for cement-based materials (CBMs). This study aims to investigate the mechanical activation (ultrafine grinding) effects of HSITs, including physical and crystallization structure effects. The particle distribution, specific surface area, density, and solubility of HSITs were tested using laser particle size analysis and other routine physical testing methods. Their crystal structures were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry-thermogravimetry (DSC-TG). Grinding reduced the particle size of HSIT particles and increased their specific surface area, wherein the minimum D50 was 5.75 μm, the maximum specific surface area was 7608 m/kg, and the corresponding grinding time was 3.5 h. With an increase in grinding time, the solubility showed an increasing trend; however, the density showed a decreasing trend. The change was fast before 3.5 h or 4 h and then slowed down, but the final solubility was still higher than its initial level, while the final density was still lower than its initial level. Grinding reduced the degree of crystallization of the minerals in HSITs and increased the microscopic strain and disorder of its crystal structure. These changes were significant for a grinding time of 0-3.5 h, after which the changes tended to be slow. The symmetry and integrity of the SiO structure decreased with grinding. The activity index of the HSIT powder was higher than 0.6. Ultrafine grinding improves the particle size distribution of HSITs and reduces the crystallinity of their main minerals, which in turn increases their chemical reactivity. It can be said that ultra-finely ground HSIT powder is pozzolanic and can be used as a mineral admixture for CBMs, and its grinding limit can be inferred to be 3.5 h.
高硅铁尾矿（HSIT）的主要化学成分是 SiO，还包括一些氧化物，如 AlO 和 CaO。机械活化可以减小 HSIT 的粒径并提高其火山灰活性，使其可用作水泥基材料（CBM）的矿物掺合料。本研究旨在研究 HSIT 的机械活化（超细研磨）效果，包括物理和结晶结构效果。使用激光粒度分析和其他常规物理测试方法测试 HSIT 的颗粒分布、比表面积、密度和溶解度。使用 X 射线衍射（XRD）、傅里叶变换红外光谱（FTIR）和差示扫描量热-热重（DSC-TG）分析它们的晶体结构。研磨减小了 HSIT 颗粒的粒径并增加了其比表面积，其中最小 D50 为 5.75μm，最大比表面积为 7608m/kg，对应的研磨时间为 3.5h。随着研磨时间的增加，溶解度呈上升趋势；然而，密度呈下降趋势。在 3.5h 或 4h 之前变化较快，然后变慢，但最终溶解度仍高于初始水平，而最终密度仍低于初始水平。研磨降低了 HSIT 中矿物的结晶度并增加了其晶体结构的微观应变和无序。这些变化在 0-3.5h 的研磨时间内很明显，之后变化趋于缓慢。SiO 结构的对称性和完整性随研磨而降低。HSIT 粉末的活性指数高于 0.6。超细研磨改善了 HSIT 的粒径分布并降低了其主要矿物的结晶度，从而提高了其化学活性。可以说，超细研磨的 HSIT 粉末具有火山灰性，可以用作 CBM 的矿物掺合料，并且可以推断其研磨极限为 3.5h。
