The Pangushan tungsten deposit is a high-medium temperature hydrothermal fissure filled quartz large vein type black tungsten deposit. The surrounding rocks are mainly metamorphic sandstone , sandy shale and quartz sandstone. The texture is tough and stable, f=8~12. The quartz veins are hard and brittle, with an inclination of 70° to 80° and an average thickness of 0.35 m. The surrounding rock has no mineralization and is in contact with the vein. The ore and surrounding rock have no agglomeration and spontaneous combustion. The vein shape is more complicated.
The stage height is 40 to 50 m. Before the mid-1960s, the main method of reserving the ore staying without leaving the column and the bottom column was adopted. The height of the top column is 2.5 to 3 m. When the ore veins are stable and the ore and surrounding rock are stable, the length of the ore block is 100-120 m. There is no central patio, and both ends are paved patios. The veins are buried turbulently, or the ore and surrounding rock are not stable. The length of the ore block is 40-60 m. One end is dug the patio and the other end is a smoothing patio. The pit bottom is used without leaving the bottom column. The structure of the nugget is shown in Figure 1. The pit bottom is shown in Figure 2.
Fig.1 The method of reserving the ore road without leaving the column and the bottom column
1-stage transportation roadway; 2-return roadway; 3-way road patio; 4-reserved heap; 5- vein; 6-patio
Figure 2 Pit wood false bottom structure [next]
In 1966, large-scale ground pressure activities occurred in the mine, and the stope and roadway were seriously damaged. Judging from the damage observed at the scene after the disaster, it is very unfavorable to prevent the damage of ground pressure without leaving the pillars, especially the top pillars. In addition, since the 1960s, the supply of pits has become more and more difficult. Since the late 1960s, the plan has been gradually changed to leave the top column without leaving a column. The height of the top column and the bottom column are each 2.5 to 3 m. The reason for not leaving the column is to facilitate the use of a smooth patio. The amount of tunneling is small, and there is no need to dig into the patio connection. The structure of the ore block is shown in Figures 3 and 4.
Figure 3: Central Patio Retaining Method without leaving a column, a top column and a bottom column
1-stage transportation roadway; 2-return roadway; 3-top column; 4-bottom column;
5-reserved heap; 6-central patio; 7-way patio
Figure 4: Retaining method without leaving a column to retain the top and bottom columns
1-stage transportation roadway; 2-return roadway; 3-top column; 4-bottom column; 5-remaining heap; 6-patio
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