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Minerals 2016, 6(2), 43; doi:10.3390/min6020043

Experimental Study on the Microstructure Evolution of Mixed Disposal Paste in Surface Subsidence Areas

1
Faculty of Land Resources Engineering, Kunming University of Science and Technology, Kunming 650093, China
2
School of Civil and Environment Engineering, University of Science and Technology Beijing, Beijing 100083, China
3
Faculty of Mining Industry, Kunming Metallurgy College, Kunming 650033, China
*
Author to whom correspondence should be addressed.
Academic Editor: Saiied Aminossadati
Received: 17 November 2015 / Revised: 2 April 2016 / Accepted: 3 May 2016 / Published: 9 May 2016
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Abstract

The integrated disposal of surface subsidence pits and surface solid waste can be realized by backfilling a surface subsidence area with a paste made from the solid wastes of mines, such as tailings and waste rock. The microstructures of these wastes determine the macroscopic properties of a paste backfill. This paper presents an experimental study on the internal structure evolution of pasty fluid mixed with different waste rock concentrations (10%, 30%, and 50%) and cement dosages (1% and 2%) under damage. To this end, a real-time computed tomography (CT) scan is conducted using medical CT and a small loading device. Results show that UCS (uniaxial compressive strength) increases when the amount of cement increases. Given a constant amount of cement, UCS increases first and then decreases as waste rock content increases. UCS is maximized at 551 kPa when the waste rock content is 30%. The paste body is a typical medium used to investigate initial damage, which mainly consists of microholes, pores, and microcracks. The initial damages also exhibit a high degree of random inhomogeneity. After loading, cracks are initiated and expand gradually from the original damage location until the overall damages are generated. The mesostructure evolution model of the paste body is divided into six categories, and this mesostructure is reasonable when the waste rock content is 30%. View Full-Text
Keywords: subsidence; mill tailings; waste rock; paste backfill; X-ray CT subsidence; mill tailings; waste rock; paste backfill; X-ray CT
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Sun, W.; Wu, A.; Hou, K.; Yang, Y.; Liu, L.; Wen, Y. Experimental Study on the Microstructure Evolution of Mixed Disposal Paste in Surface Subsidence Areas. Minerals 2016, 6, 43.

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