Research on the Influence of Mining Height on the Movement Characteristics of Overlying Strata during Extremely Thick Coal Seam Fully Mechanized Sublevel Caving Mining

Table 2

The statistics of coal recovery ratio in different stages.

Stage	4 m mining height			7.5 m mining height
	Forward distance (m)	Top coal release rate (%)	Face recovery rate (%)	Forward distance (m)	Top coal release rate (%)	Face recovery rate (%)
Primary recovery	0∼17.36	0	25.87	0∼15.04	0	48.5
Transition	17.36∼29.68	16.7	38.11	15.04∼22.08	25.4	61.2
Normal drawing	29.68∼	83.4	87.03	22.08∼	88.6	92.8