Uranium mining example - 716 mine subgrade cementation filling mining method

I. Geological overview

The silicon carbon-clay deposit is uranium deposits, ore body siliceous clay slate. The ore body is controlled by lithology and structure, and is distributed along the contact surface of shale and carbon slate. The ore-bearing lithology is slate and carbon slate. The joint development is not stable, Æ’=3~6, no water. The ore body is layered and lenticular, with a strike length of 10 to 40 m and an inclination of 30 to 80 degrees. The surrounding rock is not stable, the upper plate is composed of anthrax, the fissure is developed, a small amount of water is contained, and it is easy to fall; the lower plate is a carbonaceous slate containing vermiculite, which is broken and does not contain water. Some of the ore bodies have ancient river beds and aquifers on the upper part, and rivers, bridges and buildings on the surface.

Second, mining methods

In the past, the mine mainly used stratified caving method, which has low efficiency, high wood consumption and high radon concentration. In order to solve the above problems and to mine under the river, the ore body under the building, the downward cementation filling mining method was adopted. As shown in Figure 1.

Figure 1 Lower cementation filling mining method diagram

1—mine body; 2—filling pipe; 3—intake duct; 4—concrete filling body

The height of the stage is 25m, the thickness of the ore body is 6~8m, the inclination angle is 70°, and the length of the stope is 34m. Three patios are arranged, and the recovery tunnel is arranged along the two sides of the central patio. The width of the approach is 2.5 to 4 m, the slope is 12 to 17 degrees, and the layer height is 2.2 to 2.4 m. The two sides of the patio are mined, pedestrians, and air intake, and the central patio is filled and returned to the wind.

The mining process includes rock drilling, blasting, mining, support, filling, ventilation, etc., and the east and west wings are alternately harvested and filled. When the first layer is recovered, the roof must be supported in time. After the mining, the bottom plate is leveled, leaving a 15-20 cm thick ore cushion, pre-buried Ñ„250mm precast concrete ventilation duct, paving plastic film, closing the patio openings on both sides, and using all the goafs. Concrete filling, concrete ratio (weight) cement: sand: gravel = 1:3:5.1, compressive strength, 5.0 MPa after 7 days, 8.0 MPa after 28 days. The actual measurement shows that after three layers are recovered, the upper concrete filling body has sufficient strength and the roof pressure tends to be stable. Most of the temporary wooden pillars in the stopway before recharge can be recycled.

There is a concrete mixing station on the ground and a 400L mixer. The concrete can be slid from Ñ„300mm to the stop. Because the floor of the filling empty area has a slope of 20%~27%, the self-slip filling is smooth, the top is dense, the quality is good, and the herringbone filling body is formed. The pressure on the surrounding rock is controlled yesterday.

Third, ventilation and hail

The stope is assisted by the total load of the mine and the auxiliary fan of the local fan. The downward cementation filling method greatly reduces the concentration of radon progeny compared with the stratified caving method. The measured data are shown in Table 1.

Table 1 æ°¡ and child measured values

Fourth, the main technical and economic indicators

The comparison index of the lower cementation filling method and the stratified caving method is shown in Table 2.

Table 2 Main Technical and Economic Indicators of 716 Mine Downward Cementation Filling Mining Method