Interpretation of transient caving dust patterns during sequential caving operation in LTCC face

Longwall top coal caving (LTCC) is a mining technology introduced for enhancing the coal production rate by using the top coal caving (TCC) operations for thick seams. LTCC mine increases coal production rates but at the expense of high dust exposure and may create hazardous conditions for mine operators. It is vital for the introduction of advanced dust control technologies as well as strategies during LTCC operations for dust reduction. For developing LTCC dust control strategies, fundamental understanding of transient caving dust flow pattern across the face is necessary. Note, region above the rear armored face conveyor (AFC) is difficult to access for carrying out field measurements and hence numerical approach is the only option left for determining the dust and flow fields. In this paper, an attempt is made to predict respirable dust flow patterns during sequential caving operations in the mid face region using computational fluid dynamics (CFD) techniques. Results predicted caving dust sources entering the downstream chock and dispersing into the walkway region within 5 seconds. Respirable dust in the first downstream walkway remains below 2mg/m³ whereas in the second downstream chock in the sequence is above 2.5mg/m³. Interpreting the results, it can be inferred that caving dust controls using water sprays need to be activated in not only in the caving chock but also in the immediate downstream chock from the start of the sequence caving for preventing the migration respirable dust into the walkway regions of the downstream chocks until the completion of the sequential caving operation in all the five chocks.