The primary objective is to design a longwall scrubber system to reduce the total dust makes in the tailgate roadways in order to reduce the risk of coal dust explosion without any increase in stone dusting. An objective of this project is to examine traditional respirable dust longwall scrubber systems to evaluate their effectiveness on total dust makes. Longwall scrubber systems that are proposed include: (i) double chock shield-mounted scrubber systems in the tailgate end of the longwall face (ii) single chock shield-mounted scrubber systems in the tailgate end of the longwall face (iii) shearer-mounted scrubber systems.
Finite element techniques were used to simulate the airflow patterns and subsequent total dust behaviour along the longwall face, particularly within the tailgate end. These models were used to predict the effectiveness of the longwall scrubber systems using a series of quantitative and qualitative methods such as particle tracing and trajectory sampling.
Modelling studies indicated that shearer-mounted scrubber systems had negligible effect due to the sweeping effect of ventilating air towards the face where various chock shield-mounted scrubber system had varying degrees of success. The modelling determined that dust captures of up to 43mg/s are possible using a double chock-mounted 10m3/s scrubber system in a standard seam operation with 35m3/s across the face whereas dust captures up to 70mg/s are possible using only a single chock shield-mounted 10m3/s scrubber systems with 57m3/s across the face.
A final area of work was conducted to validate the model’s predictions. A comparative analysis of the airflow patterns through a series of velocity profiles obtained from field measurements and model simulations indicated a relatively close agreement between model generated and field measurements. The study determined that finite element techniques can be used as an excellent means of evaluating dust control techniques as it offers a great insight into the behaviour of secondary airflow, particularly within the vicinity of the shearer.