Measurements from a full-scale mock-up of a back return system for controlling the methane fringe on coalfaces were used by IMC-TS to develop a CFD model that was tested over a range of leakage scenarios. Reasonably good agreement was obtained from the CFD model which, with some further refinement, could prove a useful tool for studying such systems, where accurate physical measurements are difficult to obtain underground. This work was conducted under the ECSC project concerned with Ignition Control on Longwall Faces, and is now completed.
The other ECSC sponsored project concerning a number of different aspects of mine ventilation was also completed by IMC-TS. The main findings of the work were:
Alternative ventilation Layouts for Mine Drivages
RJB Mining (UK) Ltd, in partnership with the University of Nottingham and Deutsche Montan Technologie GmbH (DMT) of Germany completed this project at the end of 2000. There is a range of auxiliary Ventilation systems employed to ventilate headings including: force with exhaust overlap; forcing with on-board scrubber; brattice curtain with on-board scrubber; and jet fan with on-board scrubber. Dependent on local UK conditions, force and exhaust overlap systems and force with on-board scrubber fan systems are employed with continuous miner systems. Under the current interpretation of UK mining law the on-board scrubber fan is not regarded as being a primary auxiliary ventilation fan.
A series of tests performed on a scale Perspex model, measured the pressure measurements experienced across the face of the heading due to the use of a force duct located adjacent to the right hand wall of the gallery. The results obtained from the scale model experiments were subsequently used to calibrate and validate simulation results obtained from a series of representative CFD models.
A series of experimental studies were performed within a surface training gallery. The gallery included a rectangular section characteristic of a typical UK development drivage. The experiments included anemometry and the release of tracer gas. A wide range of different auxiliary ventilation configurations were simulated. A consistent series of measurements were obtained with which to gauge the relative merits of each ventilation configuration.
The CFD phase which accompanied the surface trials focussed mainly on the methane study, although there were comparisons performed against the anemometer data. The models with a scrubber duct present indicated that the pressure of this duct lessened the impact of moving the forcing duct away from the face. It also showed that the proportion of methane pulled through the exhaust fan was greater when employed in the scrubber configuration.
The final full scale experiments were conducted in an underground working drivage. In this study airflow measurements were made using vortex shedding anemometers, the heads were positioned so as to try and resolve the flow over the continuous miner. Each underground configuration was used as a basis for the final phase of the CFD study. The full report was expected to be issued in early 2001.
Improved Climatic Modelling of Mine Ventilation Networks
RJB Mining (UK) Ltd, again in partnership with the University of Nottingham and DMT have started this related project aimed at the development of a computer aided prediction model. Initial data has been collected from an underground conveyor roadway. Three temperature/humidity data loggers have been acquired with a view to recording the data continuously over a minimum of 24 hours and then downloading it onto a PC to be used as verification against the prediction model.