The Mae Moh basin is situated in the Mae Moh District of Lampang Province, which is about 26 km east of Lampang City. The basin floor is about 320340 m above mean sea level. The Mae Moh basin consists of three formations, namely the Huai King, Na Khaem, and Huai Luang formations, in ascending order. The total thickness is nearly 1 000 m in ascending order. The Na Khaem formation is a coal measure comprising three main coal zones, Q, K, and J. This study introduces preliminary approaches to

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... rmine minimum thickness to excavate thin coal seams within coal quality requirements or maximum dilution thickness acceptance. The approach considers heating value as a main parameter to determine under different scenarios of loss and dilution. The results indicate the high quality of coal-bearing soil seams, such as BK and BK3 can be excavated with K3 and acceptable dilution thickness is between 1.685.3 m at 2 800 kcal/kg of heating value. These dilution thickness can be converted to 2050 % at any excavated thickness of K3 coal seam. Low quality of coal-bearing soil seams, such as TK1, TQ and BQ4, cannot be excavated with any K and Q coal seams. Coal-bearing parting layer should have heating value more than 1,000 kcal/kg to possibly be excavated with coal seams. Abstract: The Mae Moh basin is situated in the Mae Moh District of Lampang Province, which is about 26 km east of Lampang City. The basin floor is about 320340 m above mean sea level. The Mae Moh basin consists of three formations, namely the Huai King, Na Khaem, and Huai Luang formations, in ascending order. The total thickness is nearly 1 000 m in ascending order. The Na Khaem formation is a coal measure comprising three main coal zones, Q, K, and J. This study introduces preliminary approaches to determine minimum thickness to excavate thin coal seams within coal quality requirements or maximum dilution thickness acceptance. The approach considers heating value as a main parameter to determine under different scenarios of loss and dilution. The results indicate the high quality of coal-bearing soil seams, such as BK and BK3 can be excavated with K3 and acceptable dilution thickness is between 1.685.3 m at 2 800 kcal/kg of heating value. These dilution thickness can be converted to 2050 % at any excavated thickness of K3 coal seam. Low quality of coal-bearing soil seams, such as TK1, TQ and BQ4, cannot be excavated with any K and Q coal seams. Coalbearing parting layer should have heating value more than 1,000 kcal/kg to pos-