Hydration and Pb Stabilization Mechanisms of Fly Ash–Slag-Based Mine Backfilling Binders

IF 2.6 4区环境科学与生态学 Q3 ENVIRONMENTAL SCIENCES International Journal of Environmental Research Pub Date : 2024-07-31 DOI:10.1007/s41742-024-00642-1

Chutong Zhao, Xiaona Wang, Yi Rao, Chunjiang Yu, Zhongli Luo, Jia Li, Amirhomayoun Saffarzadeh, Chuanfu Wu, Wen Ni, Qunhui Wang

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Abstract

To completely replace Portland cement for mine backfilling, MSWI fly ash (FA) and solid metallurgical wastes (ground granulated blast furnace slag, steel slag and flue gas desulphurisation gypsum) were used to prepare fly ash-slag-based binder (FBB). The effect of FA content on the hydration and Pb stabilization mechanisms of the FBB was investigated. When a small amount (15%) of FA was added to FBB, hydration product formation and compressive strength were inhibited during early curing (7 d). However, the additional Ca²⁺, SO₄²⁻ and OH⁻ carried by FA could partially promote the formation of ettringite, so that the compressive strength of 28 d was comparable to that of the treatment without FA addition (32.5 MPa). When a high amount of FA (30%) was added, the hydration process was strongly inhibited throughout the entire curing period, and the leaching concentration of Zn (1052 μg/L) exceeded the limits of the GB/T 30760–2014 standard (1000 μg/L). Pb²⁺ was also found to replace Ca²⁺ in ettringite to form insoluble Pb-ettringite and Pb₂(SO₄)O precipitates, resulting in remarkable Pb stabilisation in system. Therefore, if the amount of FA incorporated is appropriate, the use of FA as an additional cementitious material for mine backfilling is an ideal method for recycling FA.

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粉煤灰-矿渣型矿山回填粘结剂的水化和铅稳定机理

摘要为了完全替代硅酸盐水泥用于矿山回填，采用了 MSWI 粉煤灰（FA）和固体冶金废物（磨细高炉矿渣、钢渣和烟气脱硫石膏）来制备粉煤灰-矿渣基粘结剂（FBB）。研究了 FA 含量对 FBB 的水化和铅稳定机制的影响。当向 FBB 中添加少量（15%）FA 时，水化产物的形成和抗压强度在早期固化（7 d）期间受到抑制。然而，FA 所携带的额外 Ca2+、SO42- 和 OH- 可部分促进乙长石的形成，因此 28 d 的抗压强度与未添加 FA 的处理结果（32.5 MPa）相当。当添加高量（30%）的 FA 时，整个固化期的水化过程都受到强烈抑制，Zn 的浸出浓度（1052 μg/L）超过了 GB/T 30760-2014 标准（1000 μg/L）的限制。此外，还发现 Pb2+ 在埃特林岩中取代 Ca2+ 形成不溶性的 Pb- 埃特林岩和 Pb2(SO4)O 沉淀，使体系中的 Pb 显著稳定。因此，如果掺入适量的 FA，将 FA 用作矿山回填的附加胶凝材料是一种理想的 FA 循环利用方法。

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来源期刊

International Journal of Environmental Research 环境科学-环境科学

CiteScore

5.40

自引率

0.00%

发文量

104

审稿时长

1.7 months

期刊介绍： International Journal of Environmental Research is a multidisciplinary journal concerned with all aspects of environment. In pursuit of these, environmentalist disciplines are invited to contribute their knowledge and experience. International Journal of Environmental Research publishes original research papers, research notes and reviews across the broad field of environment. These include but are not limited to environmental science, environmental engineering, environmental management and planning and environmental design, urban and regional landscape design and natural disaster management. Thus high quality research papers or reviews dealing with any aspect of environment are welcomed. Papers may be theoretical, interpretative or experimental.