纳米氧化镁对不同方法制备的封井水泥水化性能的影响

IF 6.9 1区 工程技术 Q2 ENERGY & FUELS
Quanle Zou, Jinfei Zhan, Xin Wang, Zhen Huang
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引用次数: 0

摘要

瓦斯抽放是煤矿瓦斯治理的一项有效技术。高封井质量是有效抽采瓦斯的基本前提。封井过程中使用的水泥浆的膨胀性对封井效果至关重要。采用纳米氧化镁膨胀剂改善水泥浆的膨胀性,改善封井效果。采用核磁共振谱和扫描电镜研究了纳米氧化镁对不同制备方法封井水泥水化性能的影响。结果表明,纳米氧化镁质量分数的增加促进了水泥水化,且质量分数与水化效果呈正相关。不同制备方法的使用没有改变水泥中水相的分布。采用湿法混合制备时,纳米氧化镁促进了水化的诱导期、加速期和减速期;采用干法制备时,纳米氧化镁能促进水泥水化诱导期,但促进效果不如湿法制备时明显。采用湿混合制备方法时,纳米氧化镁分散均匀,扩大了反应表面积,为水泥水化产物提供了更多的成核位点,从而加速了水化反应。采用干法制备时,纳米氧化镁粉分散不均匀,存在团聚现象。在此条件下,仅聚集团簇表面的少量纳米级氧化镁颗粒参与水化,因此仅为水泥水化产物提供了少量的成核位点。这导致使用干拌法制备的水泥浆体水化不一致。随着纳米氧化镁质量分数的增加,湿拌法制备的水泥表面孔隙率先减小后增大。水泥表面水化产物致密,孔隙少,表面相对光滑。相比之下,采用干混法制备的水泥的表面孔隙率随纳米氧化镁质量分数的增加而波动,导致水泥表面粗糙,部分表面出现微裂缝。两种制备方法均降低了水泥的表面孔隙率。湿拌法比干拌法在改善水泥密实度方面更有效、更一致。研究结果为井眼密封工程中纳米氧化镁的添加和水泥制备方法的选择提供了重要指导,为实现瓦斯安全高效抽放奠定了坚实基础。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Influence of nanosized magnesia on the hydration of borehole-sealing cements prepared using different methods

Influence of nanosized magnesia on the hydration of borehole-sealing cements prepared using different methods
Abstract Gas drainage is an effective technology for gas control in coal mines. A high borehole-sealing quality is the fundamental precondition for efficient gas drainage. The expansibilities of cement pastes used in borehole-sealing processes are critical for the borehole-sealing effect. Nanosized magnesia expansive agents are used to improve the expansibilities of cement pastes and improve the borehole-sealing effect. Nuclear magnetic resonance spectrometry and scanning electron microscopy were adopted to study the effects of nanosized magnesia on the hydration of borehole-sealing cements used with different preparation methods. The results showed that an increase in the mass fraction of the nanosized magnesia promoted cement hydration, and the mass fraction was positively correlated with the promotion effect. The use of different preparation methods did not change the water-phase distribution in the cement. When using the wet-mixing preparation method, nanosized magnesia promoted the induction, acceleration, and deceleration periods of hydration; when using the dry-mixing preparation method, the nanosized magnesia promoted the induction period of cement hydration, and the promotion effect was less obvious than that seen when using the wet-mixing method. When using the wet-mixing preparation method, the nanosized magnesia was uniformly dispersed, thus enlarging the surface area of the reaction, which provided more nucleation sites for the hydration products of the cement and therefore accelerated the hydration reaction. When using the dry-mixing preparation method, the nanosized magnesia powders were dispersed nonuniformly and aggregated. Under these conditions, only a few nanosized magnesia particles on the surfaces of the aggregated clusters took part in hydration, so only a small number of nucleation sites were provided for the hydration products of cement. This led to inconsistent hydration of cement pastes prepared using the dry-mixing method. The surface porosity of the cement prepared with the wet-mixing preparation method first decreased and then increased with increases in the mass fraction of the nanosized magnesia. The cement surface exhibited compact hydration products and few pores, and the surface was relatively smooth. In comparison, the surface porosity of the cement prepared using the dry-mixing method fluctuated with increasing mass fraction of the nanosized magnesia, resulting in a rough cement surface and microfractures on some surfaces. The two preparation methods both reduced the surface porosity of the cement. The wet-mixing preparation was more effective and consistent in improving the compactness of the cement than the dry-mixing preparation. These results provide important guidance on the addition of nanosized magnesia in borehole-sealing engineering and the selection of cement preparation methods, and they also lay a solid foundation for realizing safe and efficient gas drainage.
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来源期刊
CiteScore
11.40
自引率
8.40%
发文量
678
审稿时长
12 weeks
期刊介绍: The International Journal of Coal Science & Technology is a peer-reviewed open access journal that focuses on key topics of coal scientific research and mining development. It serves as a forum for scientists to present research findings and discuss challenging issues in the field. The journal covers a range of topics including coal geology, geochemistry, geophysics, mineralogy, and petrology. It also covers coal mining theory, technology, and engineering, as well as coal processing, utilization, and conversion. Additionally, the journal explores coal mining environment and reclamation, along with related aspects. The International Journal of Coal Science & Technology is published with China Coal Society, who also cover the publication costs. This means that authors do not need to pay an article-processing charge.
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