From waste to value: Engineering properties and failure mechanisms of green backfills utilizing molybdenum tailings, fly ash and coal gangue

IF 4.6 2区工程技术 Q2 ENGINEERING, CHEMICAL

Powder Technology Pub Date : 2025-06-20 DOI:10.1016/j.powtec.2025.121294

Jun Li , Xianzhang Liu , Chang Cai , Qian Su , Minghao Chen , Xinlong Zhu

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引用次数: 0

Abstract

The sustainable reuse of industrial by-products, such as molybdenum tailings (MoTs), fly ash (FA), and coal gangue (CG), is critical for mitigating environmental risks and advancing low-carbon development. This study develops a novel green backfill material (CGMFB) using CG as aggregates and MoTs and FA as supplementary cementitious materials (SCMs), replacing 0 %–90 % of cement. The engineering properties, failure mechanisms, microstructure, and sustainability of CGMFB were systematically investigated through workability tests, quasi-static uniaxial compression tests combined with digital image correlation (DIC), advanced microstructural analyses (XRD, SEM–EDS, FTIR, TG-DTG, and MIP), along with carbon emission evaluations. The results show that SCMs replacement significantly influences CGMFB performance. With increasing SCMs replacement, flowability rises from 24 cm to 27.3 cm at 30 % before dropping to 24.5 cm at 90 %, while settling ratios increase from 5.98 % to 9.73 %. The 3-, 7-, and 28-day compressive strengths decrease linearly with increasing SCMs replacement, dropping from 22.97 to 3.85 MPa at 28 days. With higher SCMs replacement, CGMFB failure shifts from brittle to non-brittle, cracks become more complex, and uniaxial compression energy decreases. Microstructural analyses reveal that major hydration products, including C-S-H and C-A-S-H gels, are formed, while higher SCMs replacement leads to increased porosity. Notably, CGMFB carbon emissions decrease with increasing SCMs replacement. CGMFB-75, meeting engineering requirements, emits 66.33 % less CO₂ than CGMFB-0 without SCMs. This study demonstrates a sustainable pathway to transform hazardous industrial wastes into value-added green backfill materials, presenting a promising approach for low-carbon mining technologies and supporting circular economy initiatives.

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从废物到价值：钼尾矿、粉煤灰和煤矸石绿色充填体的工程特性及破坏机制

钼尾矿（MoTs）、粉煤灰（FA）和煤矸石（CG）等工业副产品的可持续再利用对于减轻环境风险和推进低碳发展至关重要。本研究开发了一种新型绿色回填材料（CGMFB），使用CG作为骨料，MoTs和FA作为补充胶凝材料（SCMs），取代了0% - 90%的水泥。通过可加工性试验、结合数字图像相关（DIC）的准静态单轴压缩试验、先进的微观结构分析（XRD、SEM-EDS、FTIR、TG-DTG和MIP）以及碳排放评估，系统地研究了CGMFB的工程性能、破坏机制、微观结构和可持续性。结果表明，SCMs的替换对CGMFB性能有显著影响。随着SCMs替换量的增加，流动性从30%时的24 cm上升到27.3 cm， 90%时下降到24.5 cm，沉降率从5.98%上升到9.73%。3、7和28天的抗压强度随着SCMs更换量的增加而线性下降，28天时从22.97 MPa下降到3.85 MPa。随着SCMs替换量的增加，CGMFB破坏由脆性向非脆性转变，裂纹变得更加复杂，单轴压缩能降低。微观结构分析表明，形成了主要的水化产物，包括C-S-H和C-A-S-H凝胶，而更高的SCMs替换率导致孔隙度增加。值得注意的是，CGMFB碳排放量随着SCMs替代量的增加而减少。CGMFB-75的CO2排放量比无SCMs的CGMFB-0低66.33%，满足工程要求。本研究展示了一条将危险工业废物转化为增值绿色回填材料的可持续途径，为低碳采矿技术和支持循环经济倡议提供了一条有前景的途径。

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来源期刊

Powder Technology 工程技术-工程：化工

CiteScore

9.90

自引率

15.40%

发文量

1047

审稿时长

46 days

期刊介绍： Powder Technology is an International Journal on the Science and Technology of Wet and Dry Particulate Systems. Powder Technology publishes papers on all aspects of the formation of particles and their characterisation and on the study of systems containing particulate solids. No limitation is imposed on the size of the particles, which may range from nanometre scale, as in pigments or aerosols, to that of mined or quarried materials. The following list of topics is not intended to be comprehensive, but rather to indicate typical subjects which fall within the scope of the journal's interests: Formation and synthesis of particles by precipitation and other methods. Modification of particles by agglomeration, coating, comminution and attrition. Characterisation of the size, shape, surface area, pore structure and strength of particles and agglomerates (including the origins and effects of inter particle forces). Packing, failure, flow and permeability of assemblies of particles. Particle-particle interactions and suspension rheology. Handling and processing operations such as slurry flow, fluidization, pneumatic conveying. Interactions between particles and their environment, including delivery of particulate products to the body. Applications of particle technology in production of pharmaceuticals, chemicals, foods, pigments, structural, and functional materials and in environmental and energy related matters. For materials-oriented contributions we are looking for articles revealing the effect of particle/powder characteristics (size, morphology and composition, in that order) on material performance or functionality and, ideally, comparison to any industrial standard.