Investigating the Impact of Caving on Longwall Mine Ventilation Using Scaled Physical Modeling

Abstract

In longwall mining, ventilation is considered one of the more effective means for controlling gases and dust. In order to study longwall ventilation in a controlled environment, researchers built a unique physical model called the Longwall Instrumented Aerodynamic Model (LIAM) in a laboratory at the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Mining Research Division (PMRD) campus. LIAM is a 1:30 scale physical model geometrically designed to simulate a single longwall panel with a three-entry headgate and tailgate configuration, along with three back bleeder entries. It consists of a two-part heterogeneous gob that simulates a less compacted unconsolidated zone and more compacted consolidated zone. It has a footprint of 8.94 m (29 ft.) by 4.88 m (16 ft.), with a simulated face length of 220 m (720 ft.) in full scale. LIAM is built with critical details of the face, gob, and mining machinery. It is instrumented with pressure gauges, flow anemometers, temperature probes, a fan, and a data acquisition system. Scaling relationships are derived on the basis of Reynolds and Richardson numbers to preserve the physical and dynamic similitude. This paper discusses the findings from a study conducted in the LIAM to investigate the gob-face interaction, airflow patterns within the gob, and airflow dynamics on the face for varying roof caving characteristics. Results are discussed to show the impact of caving behind the shields on longwall ventilation.

Bibliometric analysis and review of mine ventilation literature published between 2010 and 2023

“…Furthermore, "longwall" appeared twice in the theme research Cluster #9, indicating that longwall ventilation is also a research hotspot in the field of mine ventilation. For instance, Gangrade et al developed a similar geometric model and conducted simulation analyses of longwall ventilation under different caving scenarios [ 108 ]. However, it's important to note that underground mine disasters often involve multiple hazards occurring simultaneously.…”

Control strategies for ventilation networks in small‐scale mines using an experimental benchmark

“…On the other hand, scale models have been implemented to investigate the behavior of air flow in underground mining. [12] presents the results of the Pittsburgh-based, 1:30 scale physical model, the Longwall Instrumented Aerodynamic Model (LIAM), equipped with sensors, actuators, and a data acquisition system to verify air flow and dynamics for varying roof caving characteristics. In the same way, experimental models have been used to study the dynamic behavior of ventilation networks regulated by means of the control strategies presented in [13,14].…”

A Field Study of Longwall Mine Ventilation Using Tracer Gas in a Trona Mine

“…Numerical modeling research utilized computational fluid dynamics modeling and discrete fracture network modeling concept [5]. Physical modeling research was conducted on a 1:30 scale physical model called “Longwall Instrumented Aerodynamic Model (LIAM)” [6–8]. The findings described in this paper contribute towards the overall assessment of ventilation of longwall mines.…”