1. Overview
The 116'6-3 coal mining face requires forced caving. In order to ensure the safety of the forced caving process, the following measures are specially formulated.
2. Special support and return pillars
1. The working surface is supported by hinged top beams and single hydraulic pillars. The columns are driven according to the column spacing and row spacing. The column spacing is 0.7m (the column spacing at the leading point of the fault is 0.5m) and the row spacing is 1m. The pillars are required to face the mountain strongly, and the angle of facing the mountain is 2° to 3°. Tighten the columns firmly and arrange them in rows. The initial supporting force of the columns should be ≥60kN.
2. The safety exits above and below the mining surface are supported by four pairs of eight beams.
3. Double rows of columns should be built within the range of 10m from the coal wall in the return air lane of the working face and the transport lane of the working face, and single rows of columns should be built within the range of 10 to 20m. The height of the advance support sidewalk should not be less than 1.6 m, the width is not less than 0.7m.
4. Use single hydraulic props to add 2 props to each space between the last row of basic columns on the mining surface to form bald columns as inclined dense columns, one of which is used as a backup column for the basic columns.
5. A shed should be erected every 5m in the top row. If the wooden pillars of the shed are found to be broken, they should be replaced in time.
6. A "#" shaped wooden stack should be set up every 15m on the mining surface. The floating coal and gangue at the place where the wood pile is struck must be cleaned, and the four corners of the wood pile must be square, stacked layer by layer, and connected to the top. After the initial topping of the mining surface is completed, the wood pile can be cancelled.
7. When returning to the column, it is strictly necessary to support first and then return, from bottom to top, and from the old pond to the coal wall.
8. Arrange three people for the column return point, one of whom will control and operate the column return device. The column where the column return device is installed must be filled with fluid to ensure it is firm. One experienced person is dedicated to watching the mountain and the top, and one person is roping the hook to unload the column. The person who has hung the hook must retreat to a safe place diagonally above the return point and clear the retreat before twisting the column return device to return the column. Personnel are strictly prohibited from entering the empty ceiling area for work. If the pillars are dumped into the empty area after being unloaded, long-handled tools must be used to remove the pillars.
9. During the column return process, if signs of pressure or unsafe hazards are found that threaten personal safety, promptly evacuate personnel along the coal wall to safe locations in the upper and lower tunnels until the roof is stable and unsafe hazards are removed. After elimination, the column backing work can be carried out.
3. Forced roof caving
1. Members of the mine roof management leading group must insist on on-site follow-up during the forced caving period. When hidden dangers are discovered, immediate measures must be taken on site to deal with them.
2. Use two-thirds of the cut logs with a diameter of ≤0.1m to support the signal pole in Laotang. If the signal column is found to be broken and signs of roof pressure appear (such as the roof falling seriously, the pillar making noise), all mining personnel must evacuate to a safe location 50m away from the working surface. Wait until the roof is stable before entering the work site and continuing work.
3. Forced roofing operation: drill a row of holes at an angle of 45° on the roofing row, with a depth of 1.5m and a spacing of 1.2m between the holes on the roof. Each blasthole is loaded with 4 sections of explosives and a detonator, and the remaining part is sealed with yellow mud. The blasting order is from bottom to top, and no more than 5 blasts can be fired at a time.
4. If the roof does not come down after the first forced roofing, after 2 rows of mining on the mining surface, the second forced roofing will be carried out until the roof collapse height reaches 1.5 times of the mining height, and the roofing will be forced. Just ended.
IV. Others
1. After each shift of staff arrives, they must strictly implement the system of knocking for help and asking for support, and pay attention to the roof, support, etc. at the work site at all times. Any problems discovered must be rectified immediately, and empty-top operations are strictly prohibited.
2. Mechanical and electrical equipment should be placed neatly on the shelves and managed with tags to ensure that they are in good condition and will not explode.
3. The end time of forced topping is determined by the topping management leading group.
4. Other matters shall be strictly implemented in accordance with the "116′6-3 Coal Mining Face Operating Procedures".
5. This measure will be implemented after thorough study by all employees in the team.