Pressure Study on Pipe Transportation Associated with Cemented Coal Gangue Fly-Ash Backfill Slurry

Jie Yang,Baogui Yang,Mingming Yu

doi:10.3390/app9030512

Jie Yang, Baogui Yang + Show 1 more

Open Access

https://doi.org/10.3390/app9030512

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Journal: Applied sciences	Publication Date: Feb 2, 2019
Citations: 16	License type: CC BY 4.0

Affiliation: China University of Mining and Technology

Abstract

Cemented coal gangue-fly ash backfill (CGFB) slurry has commonly been used to control subsidence damage caused by underground coal mining. This paper discusses the characteristics of CGFB slurry fluidity in its pipe transportation. A general description about the components of the CGFB is provided involving the percentage of composition, particle size distribution (PSD) and rheological performance. The CGFB flow characteristics of the slurry pipeline were simulated in a straight pipe and 90° elbow pipe, respectively, combined with the pressure loss and conveying velocity distribution. With the help of the commercial computational fluid dynamic (CFD) code FLUENT, the modeling was conducted with various slurry feeding velocities. These results showed the local resistance loss in a bending pipe is significantly higher than the resistance in a straight pipe under the same conditions associated with CGFB transportation. The velocity distribution of the slurry solid particles in the slurry’s movement forward is more decentralized as the hydraulic inlet velocity increases. Based on these simulation data, a correlation was developed to predict the resistance loss of the CGFB slurry as a function of the hydraulic inlet velocity, pipe diameter and CGFB slurry rheological characteristics.

Highlights

Longwall mining is the most efficient underground means of recovering coal resources and is widely used in China, the United States, Australia and Europe [1]
The simulations are conducted at feeding velocities of 1.4 m/s, 1.6 m/s, 1.8 m/s, 2.0 m/s and 2.2 m/s with a solid concentration of the cemented gangue-fly ash backfill (CGFB) slurry sustained at 76.05%
Unlike the straight pipe flows, where streamlines show an organized pattern, elbow pipe flow is characterized by apparently random motion of the fluid in the flow and its complicated physics need to be understood for better prediction and control of the flow in the slurry pipe transportation engineering

Summary

Introduction

Longwall mining is the most efficient underground means of recovering coal resources and is widely used in China, the United States, Australia and Europe [1]. This type of mining method has produced serious surface subsidence issues, which cause surface structure deformation, groundwater discharge and plant recession due to the formation of subsidence basins [2]. In China, various backfill techniques have been invented and implemented to protect surface structures from damage [3]. The cemented gangue-fly ash backfill (CGFB) slurry is one type of novel backfill material which has been utilized in the backfill technology [4]. The slurry solidifies into a hard body and combines with the surrounding rock mass to

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Conclusion