Abstract
Cemented waste rock backfill (CWRB), which is a mixture of tailings, waste rock, cement, and water, is subjected to combination actions in underground mining operations and has been widely used in deep resource mining. While the strength requirement and macroscopic deformation behaviors of CWRB have been well studied, the mesoscopic damage evolution mechanisms are still not well understood. In this work, a CWRB sample with a waste rock proportion of 30% was studied with a uniaxial compression test under tomographic monitoring, using a 450 kV industrial X-ray computed tomography (CT). Clear CT images, CT value analysis, crack identification, and extraction reveal that CWRB damage evolution is extremely inhomogeneous and affected by the waste rock size, shape, and distribution. Furthermore, the crack initiation, propagation, and coalescence behaviors are limited to the existing waste rocks. When deformation grows to a certain extent, the cracks demonstrate an interlocking phenomenon and their propagation paths are affected by the waste rocks, which may improve the ability to resist compressive deformation. Volumetric dilatancy caused by the damage and cracking behavior has closed a link with the meso-structural changes, which are controlled by the interactions between the waste rocks and the cemented tailing paste.
Highlights
Due to the exhaustion of shallow mineral resources, the exploitation of deep mining resources is in urgent need
This paper presented the results of in-situ uniaxial compressive experiment on cemented waste rock backfill for the Lilou mining, using X-ray computed tomography (CT)
A specially designed loading device had been used to match the high energy CT machine and it was demonstrated that loading device had been used to match the high energy CT machine and it was demonstrated that the transparent X-ray loading device provided an excellent non-destructive tool for investigating the transparent X-ray loading device provided an excellent non-destructive tool for investigating the the mesoscopic mechanical behaviors of the cemented waste rock backfill (CWRB) sample
Summary
Due to the exhaustion of shallow mineral resources, the exploitation of deep mining resources is in urgent need. The deep mining process involves the removal of waste material from rock mass and the recovery of economically useful minerals [1,2]. Mining activity results from formation of plenty of underground gobs. A technology of backfilling is usually expected to fill the underground cavities by using the waste materials from the mining process [2,3,4,5]. Many backfilling technologies have been used in the mining industry, such as cemented paste backfill (CPB), hydraulic sand backfill, and waste solid backfill. The CPB mining technology refers to the method of backfilling the underground gobs by mixing waste materials and binding material together and pumping them underground [2]
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