A study of the formation and control of dust at the ends of highly mechanised longwall faces. Final report on CEC Contract 7260-03/022/08

With the advance in technology and advent of more powerful and efficient coal-getting machines, recent developments within the mining industry have been concentrated on new techniques of roadway drivage and construction. A variety of new machines and face end configurations have been tried in order to match the greater advance rates being achieved by modern coal-getting machines. This in turn has created a number of problems for dust control engineers. This study set out to evaluate airborne dust conditions of a number of face end configurations, including in-line rippings (where the roadway is advanced in line with the coalface) and mechanised advanced headings using different types of machines and auxiliary ventilation. Because of the stated policy of the British Coal Corporation to change, wherever possible, to retreat mining, two retreat face ends were also included in the study.Early in the trial it was observed that elevated dust concentrations measured in an advanced heading on the return side of the face could be attributed to the dust from the coal-getting machine “”pluming”” along the face track and being drawn preferentially into the heading. A study was set up on the Institute of Occupational Medicine’s V10 scale model coalface to study the plume profiles. These studies showed that the plume concentration falls approximately exponentially from the coalface to the travelling track, and that the concentrations close to the coalface can be more than 100 times those in the travelling track. The plume also remains essentially intact as it turns into the advanced heading, which indicates where free standing filtration units may best be sited to capture the plume.Underground trials in advanced headings demonstrated the efficiency of air curtains on heading machines, and showed that heading teams are almost always exposed to airborne dust travelling up the heading from behind. They also demonstrated that for headings at the intake ends of faces, providing methane concentrations can be controlled, the preferential method of dust control is by partial recirculation ventilation through a filtration unit. “”