Coal mining — liu jianh unit: date of hebei polytechnic university: blasting coal, artificial coal, mechanical coal transport, mono-column immediate (after liberation to early 60) pucce: coal mining, coal loading (from early 60 to early 70): total mechanization of the five main processes (from mid-70 to the present) date cannons in the early stages of development of the nation + whole front of the wood pillar + crushable plate transporter + metal friction pillar + 铰 (a) a single-hull hydraulic pillar in the 1980s + plowboard + mobile coal sheet datepu mining development in the 1950s, deep-seated coal miners (~) + disassembly transmitter + wood pillar; after the '60s, the first generation of shallow deep coal miners (~): shallow deep coal miners + whole moving curved blades + rubbed metal pillars + 铰 second generation of sorghum (late 1970s): shallow deep coal digger + monomer hydraulic pillar at high complementary levels; third generation (mid-1980s): unchained double-roller coal-mining machine + double-speed unsealed scrapboard + long steel beam date integrated development process fully mechanized (70 cs. To date). In 1973, integrated mechanized coal-mining equipment was introduced, 2000 %, %: eye-to-eye, gun-to-fire coal, hand-loading coal, board-carrying transporter, push-transmitter, man-in-hand protection and back-posting. I. The requirements for the demolition of a detonated coal are: accurate progress, even coal blocks, no damage to the ceiling, no coal, straight coal walls, no pillars, and low consumption. Videodate (1) eyl: depending on the thickness of the coal layer and the rigidity of the coal layer, single-eyed: typically used for thin coal layer m1m or coal-based software, and for the management and development of the coal layer. (a) two eyes: eye-to-eye, three eyes and triangular eyes; generally used for the mining of small, medium-heavy coal layer m=1 . Three pairs of eyes (five eyes): used for hard coal or for the extraction of large, medium-heavy coal layer m-tips. = 1 zirconium, protective support, not to cause a coal to fall into an empty area, reasonable depth of the gun's eye: usually depending on the foot, (2) the distance and depth of the gun's eye
