Longwall single-layer caving mining method using metal hydraulic support roof for shallow well mining area in Mingshui bauxite mine

(1) Technical conditions for mining of test nuggets. The inclination angle of the ore body is 5°~7°, the thickness is 1.53~2.32m, the average thickness is 1.7m, the length of the ore block is 180m, and the working face is 42m long. The ore is a special hard clay mine. f=3~5. Direct mudstone roof iron, the thickness of 4m, brittle friable, joint development, easy to take off. Purple bottom shale, medium hardness, i.e. parallel to bedding joint development, scraper rake mine frangible bottom slate stone.
(2) SZ1-1320 eight-column-supporting metal composition swing hydraulic support main dimensions: a support bracket high 1300 ~ 2000mm; Support area 8m 2, the top plate covering the extent of 72%; bracket arrangement pitch of 2200mm (width of the bracket comprises 2080mm), The gap is 120mm and the total weight of the bracket is 8200kg.
Metal hydraulic support structural components: covering the top plate, column, shifting jack, adjusting jack, operating system, etc.
The high-pressure emulsion pumping station of the metal hydraulic support is arranged in the transportation communication tunnel, no more than 100m away from the mining working surface, and is connected with the hydraulic support of the working surface through the high-pressure hose.
(3) The erection of the metal hydraulic support on the mining face is shown in Figure 1. Cutting the mountain to the 6m wide (temporary support of some wooden columns), the metal hydraulic support components are transported into the stop for assembly. The hydraulic support is arranged vertically with the longwall working face. The spacing between the frame and the frame is 0.2m, which is arranged in a straight line. There is a 1.2m rock drilling and transporting work space between the bracket and the working surface. A metal mesh is placed between the top beam of the bracket and the top plate to prevent the gravel from falling into the work surface. The front end of the bracket is provided with a curtain (made of steel plate) and a baffle (made of waste conveyor tape) to prevent the ore from falling into the gap of the bracket and being lost.

Figure 1 Metal hydraulic support layout in the stope
1-wood pillar; 2-minening well; 3-metal hydraulic support; 4-metal mesh [next]

(4) The working condition of the hydraulic support. The hydraulic support can actively support the top plate. The initial support force is 0.192×10 6 N per column, and each frame is 1.54×10 5 N. With the roof sinking and ground pressure increasing, the working resistance of the hydraulic support is supported (0.588×10 6 per column). N) Each case is 4.70×10 5 N, which is subjected to the pressure of the top plate and controls the sinking of the top plate. The transfer process is to start the transfer when the ore is finished, first remove the baffle, hang the wire mesh at the top of the probe beam, and move the frame from the bottom to the top along the working surface, and move each frame twice. After the sub-frame moves forward one step and supports the top plate, the main frame is moved again, two steps are moved each time, each step is 0.5-0.6 m, the bracket moves forward, and the top plate collapses. Each time the transfer time is 1.5 to 2 hours.
(5) Mining operations cycle and labor organization. The mining operation cycle is two shifts per day, one shift. Implement the labor organization form of the professional operation team. The shifting work is responsible for the work of shifting, rock drilling, blasting, funnel shifting and returning to the column. The first mining class only carried out mining operations, with a total of 8 people, including motor vehicle driver workers. The second mining class carried out rock drilling, blasting and mining operations. The whole class consisted of 10 people, including 4 rock drillers and 7 shifting classes, 4 of which were rock drilling and blasting. The team has a total of 25 people.
(6) Compared with the wood column support, the metal hydraulic support covers 72% of the roof area, while the wooden pillar is only 16%, so the workers work safely; the metal hydraulic support has a large initial force, and the area where the roof is first appeared is small and periodic. The ground pressure is not obvious, the amount of roof subsidence is also reduced, and the top distance is 3.6m from wood support, which can be increased to 5.9m and the minimum is 3.9m. There is no piece of work and topping phenomenon in the working face, and the roof management is easy; the heavy manual labor of the workers supporting the wooden column is alleviated; the working condition of the electric slag mine is improved, and the maximum daily production capacity of the nugget is 265t, which is higher than that of the wooden support ore 37%; increased ore recovery rate, up to 94.3%; saved a lot of pit wood; the cost per unit of ore is reduced by 3.8% compared with wood support.
(7) Applicable conditions. The thickness of the ore body is within the range of 1.3~2m, and the ore body is required to be stable, the top and bottom plates are basically flat; the ore body has little change along the strike and the tendency; the length of the ore body is as long as possible, preferably more than one year. Quantity, otherwise it takes one month to install and disassemble the support of one stope, and the proportion of time is too large; the inclination of the ore body should not exceed 15°; there should be no large faults in the ore block, otherwise it will be difficult to pass the fault.
(8) Main technical and economic indicators. The technical and economic indicators of the test nuggets are: production capacity of 265t / d, mining labor productivity of 7.36 tons / work class, ore recovery rate of 94.3%, pit wood consumption of 83.7m 3 / kt, metal mesh consumption of 494.8 / 10,000 tons, explosives Consumption 0.16kg / t, fuse consumption 0.72m / t, detonator consumption 0.52 / ton, unit ore cost (direct cost) 7.29 yuan / ton.

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