An Improved Composite Fly Ash Gel to Extinguish Underground Coal Fire in Close Distance Coal Seams: A Case Study

Table 2

Coal seam features.

Coal seam no.	Thickness of coal seam	Distance of coal seam (m)	Stability	Recoverability	Apparent density (m^3)	Lithology of the roof and floor				Dip angle (°)
						Roof	Symbol	Floor	Symbol
1	3.1	15.93	Stable	Minable	1.35	The black sandstone		Black powder sandstone		36
2	4.86	14.07	Stable	Minable	1.35	Medium sandstone		Silstone		35
3	1.86	39.84	Stable	Minable	1.35	Coarse sandstone with quartz		Medium sandstone		35
4	3.26	24.4	Stable	Minable	1.35	Gravel sandstone		Silstone		34
5	5.32	32.14	Stable	Minable	1.35	Coarse sandstone with quartz		Silstone		35
6	3.03	34.88	Stable	Minable	1.35	Gravel sandstone		Silstone		35