Abstract
The tailing paste thickening technology was investigated to achieve goaf reduction treatment and tailing resource utilization of metal mines and reach the effect of controlling two hazards with one waste. However, superfine tailing particles could easily form suspended water-locking flocs in the thickening process, which seriously affected the increase in the underflow concentration in the thickener. Undisturbed compression-stage bed samples were extracted using an in situ sampling method through a continuous dynamic thickening experiment. Then, the morphologies and geometrical structures of micropores were analyzed through high-precision computed tomography scanning. Subsequently, the influences of the shear evolution of pore structure and seepage channel on the dewaterability of underflow slurry were explored by combining Avizo software and 3D reconstruction technology. The thickening and dewatering mechanism of underflow slurry was also revealed. Results showed that under the shear action, the flocs were deformed and compacted, forming a high-concentration underflow. On this basis, the original micropores were extruded, deformed and segmented. Moreover, many loose micropores were formed, the connectivity became poor and the total porosity declined. The diameter of the water-conducting channel in the sample was enlarged because of the shear force and the seepage effect improved. The maximum flow velocity inside the pores was 1.537 μm/s, which was 5.49% higher than that under the non-shear state.
Highlights
The mining industry is vital for national security and economic development [1,2,3,4]
A large quantity of moisture cannot be drained, leading to the low concentration of underflow slurry; this scenario has become a bottleneck in the development of the paste filling method [10,11,12,13]
This finding indicated that the unclassified tailing bed thickening effect could be enhanced by the shear action
Summary
The mining industry is vital for national security and economic development [1,2,3,4]. The preparation of unclassified surface tailings into paste materials is not prone to dewatering, segregation and precipitation caused by underground paste filling and surface paste stockpiling This technology utilizes surface wastes to eliminate tailing reservoirs gradually; it can govern underground goaves and control the collapse of mines, reach goaf reduction and tailing resource utilization of metal mines and contribute to the sufficient recycling of water resources. Deng et al [24,25] analyzed the relationships of compressive strength with the proportion of pores with different radiuses and fractal dimensions according to the nuclear magnetic resonance porosity tests and the fractal characteristics of pore structure They explored the microporous characteristics of cement tailing backfilling and determined that the floc net structure is an underlying cause that influences the dewatering effect and rheological parameters. A 3D Representative Elementary Volume model was constructed to reflect the morphological and geometrical structures of the micropores in the slurry, probe the influence of the shear evolution of pore structure pore structure and seepage channel on the dewaterability of underflow sl its thickening and dewatering mechanisms
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