Intelligent technology of first-mining face of longwall top-coal caving with super large cutting height in extra-thick and hard coal seam

Based on the occurrence conditions of coal seams that are shallow covered, extra-thick and hard in Yushen mining area, we analyzed the challenges of first-mining face of intelligent longwall top-coal caving(LTCC)face with super large cutting height, and put forward the corresponding countermeasures, which aimed to improve the automatic and intelligent level and reduce the number of personnel working at the longwall face.This paper discussed the influence of the structure of hydraulic roof support on the intelligent mining, stability of the support system and the cavability of top-coal at the LTCC face with super large cutting height.It is concluded that the two-legged shielding type hydraulic support with face sprag of two-stage and integral structure is more suitable for LTCC face with super large cutting height.Aimed at the issue of the top-coal caving arch, we analyzed the form of top-coal caving arch and measures of arch breaking, and put forward the intelligent swinging strategy of tail canopy, which is “small-range swing for small arch, great-range swing for large arch”, so as to improve cavability and drawing efficiency of the top-coal.There are problems such as insufficient comprehension of the actual caving and drawing migration law and immature technology of coal and gangue identification at the first-mining face of LTCC with super large cutting height.The mixed fuzzy section of coal and gangue was explained, which separated the top-coal into two sections: pure coal section and mixed fuzzy section of coal and gangue.We proposed that the intelligent memory coal drawing could be used for the pure coal section and the artificial interventional coal drawing could be adopted for the mixed fuzzy section of coal and gangue.This measure could reduce the amount of labor, as well as ensure the top-coal recovery rate and limit the rate of gangue content.A comprehensive evaluation system of caving effect was established, which combined online intelligent evaluation of ash content detection and manual on-site evaluation.Through remote drawing keyboard and remote drawing feedback evaluator, drawing technicians can timely and accurately control the drawing process and give feedback evaluation.Subsection and group drawing measure was put forward to improve the coal drawing efficiency and promote the coordination of coal cutting and drawing.The technical research on the first-mining face of intelligent LTCC with super large cutting height can provide references for other LTCC faces with similar mining conditions.