College of Civil Science and Engineering, Yangzhou University, Yangzhou, 225127, China.
College of Civil Science and Engineering, Yangzhou University, Yangzhou, 225127, China.
Environ Res. 2022 Nov;214(Pt 2):113912. doi: 10.1016/j.envres.2022.113912. Epub 2022 Jul 19.
Herein, to reduce CO emissions and energy consumption and to promote the recycling of waste resources, two types of boron-containing MgO by-products, which were obtained by lithium extraction from Qarhan Salt Lake, China, were used as substitutes for dead-burned MgO to prepare magnesium phosphate potassium cement (MKPC) as a rapid repair material. First, the phase composition and particle-size distribution of the MgO by-product were investigated. The effects of different MgO sources, molar ratio of MgO to KHPO (M/P), and curing age on the setting time and mechanical properties of MKPC were then studied. Based on the results, the mix proportion of MKPC was optimized. Finally, X-ray diffractometry, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), differential thermogravimetric (DTG) analysis, and mercury intrusion porosimetry were used to characterize the phase and microstructure evolution of MKPC prepared with different MgO contents. The results demonstrated that the by-product MgO prolonged the setting time of MKPC to more than 40 min. In addition, in the initial stage of hydration, the compressive strength of the MgO by-product was slightly lower than that of the dead-burned MgO; however, with increasing age, the mechanical properties of MKPC prepared by by-product MgO were excellent (up to 60 MPa). The phase and microstructure results revealed that the main hydration product of MKPC prepared using the three types of MgO was MgKPO·6HO. Combined with the physical and chemical properties of the raw materials, it was confirmed that the larger particle size and the coexisting impurities from the salt lake were the main reasons for the longer setting time of the MKPC prepared by the by-product MgO. We believe that this research will be of great significance for the preparation of low-carbon, low-cost, and high-performance MKPC materials.
在此，为了减少 CO 排放和能源消耗，并促进废物资源的循环利用，我们使用了从中国察尔汗盐湖提锂得到的两种含硼氧化镁副产品，替代死烧氧化镁来制备磷酸镁钾水泥（MKPC）作为快速修复材料。首先，研究了 MgO 副产品的物相组成和粒径分布。然后，研究了不同 MgO 来源、MgO 与 KHPO 的摩尔比（M/P）和养护龄期对 MKPC 凝结时间和力学性能的影响。在此基础上，优化了 MKPC 的配合比。最后，采用 X 射线衍射、扫描电子显微镜结合能谱（SEM-EDS）、差示热重（DTG）分析和压汞法，研究了不同 MgO 含量制备的 MKPC 的物相和微观结构演变。结果表明，副产品 MgO 使 MKPC 的凝结时间延长至 40 分钟以上。此外，在水化初期，副产品 MgO 的抗压强度略低于死烧 MgO；但随着龄期的增加，副产品 MgO 制备的 MKPC 的力学性能优异（高达 60MPa）。物相和微观结构结果表明，三种 MgO 制备的 MKPC 的主要水化产物均为 MgKPO·6HO。结合原材料的物理化学性质，确定副产品 MgO 较长的凝结时间主要归因于其较大的粒径和盐湖共存的杂质。我们相信，这项研究对于制备低碳、低成本、高性能的 MKPC 材料具有重要意义。
