Method for determining the critical velocity of paste-like slurry filling into goaf using computational fluid dynamics
- PDF / 5,632,523 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 29 Downloads / 160 Views
ORIGINAL PAPER
Method for determining the critical velocity of paste-like slurry filling into goaf using computational fluid dynamics Hao Wang 1
&
Chengwei Zhao 1,2 & Sicheng Chen 1
Received: 18 October 2018 / Accepted: 22 July 2019 / Published online: 13 August 2019 # Saudi Society for Geosciences 2019
Abstract The coal mining mode of paste-like slurry fill shows the connotation and characteristics of green mining both in the resource recycle and waste reuse. Test by intelligent torque sensor, fitted by the ORIGIN software, the following relationships were obtained: (1) rheological parameters versus slurry mass fraction, (2) rheological parameters versus component ratio. Based on the relationships, the recommended ratio of paste-like slurry was determined. The mass concentration of slurry is no more than 78%, which is composed by coal gangue (diameter < 20 mm), fly ash (diameter < 30 μm), and gelling agent with the weight ratio of 8:3:1. The pipe flow dynamic characteristics of paste-like slurry have been analyzed by computational fluid dynamics (CFD) and CFD-POST. By simulating the flow behavior of the slurry at different velocities under a stable state in the horizontal pipe, the analysis of the paste-like slurry’s non-silting velocity has been done. Combined with the laboratory test data and mechanical models, the different concentrations and the velocities of the paste-like slurry in pipelines under different inlet velocities were introduced. The critical velocity is about 1 m/s corresponding to a pipe diameter of 150 mm. The results provide a better insight into the process of transportation of paste-like slurry, as well as to more cost-effective engineering designs of sustainable development of the environment and coal mines. Keywords Coal mining . Paste-like slurry . Critical velocity
Introduction In 2017, the total coal production of China was 3.5 × 109 tons, of which more than 70% came from underground coal mining (China National Coal Association). More than 5 × 109 tons of gangue has been deposited as large-scale waste dumps which occupied large number of landmass (Miao and Qian 2009; Qian 2010). Underground coal mining causes land subsidence which threats the buildings and water systems on the surface above the goaf. At the same time, harmful gases formed by waste coal spontaneous combustion formed a destructive substance such as acid rain, and so forth. Editorial handling: Domenico M. Doronzo * Hao Wang [email protected] 1
School of Energy & Mining Engineering, China University of Mining & Technology, Beijing 100083, China
2
State Key Laboratory for Geomechanics and Deep Underground Engineering, Beijing 100083, China
In the 2000s, paste-like backfilling methods were developed in coal mines. Generally speaking, the successful filling into goaf includes the effective material transportation and the sufficient strength of the filling body that could support roofs does not sink (Huang 2014a, b). The paste-like slurry is made up of aggregate material (gangue, fly ash) with concent
Data Loading...
