Early ditch gold mining gold from east to west with a total ore block east, west ore block and three ore block grid Lou Aung, respectively, occurs in ~ 1 # 4 # ditch: East ore block is located 1 # 2 # ditch ~ The main part of the mineralized belt spreads NE direction, the length is more than 1000m, the width is more than 300m, and the direction is 50°~70°. The main ore body is inclined to the left, the width is relatively stable, the alteration mineralization is strong, the grade is high, and the distribution is Au1, Au9 and Au153 main ore bodies; the west ore section is located in the 3# ditch, the main part of the mineralized belt is NW direction, extending more than 300m, the width is more than 50m, the strike is 300°~320°, the inclination angle is slow, the thickness is stable, and the eclipse is The mineralization is stronger and the grade is higher. The Au14 main ore body and the Au27 ore body are distributed. The Geyuang section is distributed in the 4# ditch of the early Zigou and the Ge'angang village of Xiahe County. The main part of the mineralized belt is distributed near the SN. The extension is greater than 1000m, the width is greater than 500m, the strike is 350°~10°, the extension is stable, the thickness and the occurrence are little changed, the alteration mineralization is weaker than the eastern ore section, and the ore grade is lower than that of the east and west ore sections. The segments are distributed with Au26, Au29, Au30 and Au314 main ore bodies.
According to the scale of the deposit and the occurrence conditions of the ore body, the mining and production scale of the early Zigou gold mine is 600,000 t/a. The mine service period is 10 years, and the mining is carried out in stages. The first-stage mining of high-grade ore (to achieve industrial grade) and the second-stage mining of low-grade ore (currently failing to reach industrial grade). The mining scope is the entire ore body (industrial grade ore body) in which the mine submits reserves within the mining rights plane. In the depth, more than 3000m is the mining range, and below 2650m is the prospecting range, and the lowest elevation is 2650m. The mine was mined in 2004 and used underground mining.
1 mining method selection
According to the occurrence conditions of the ore body and the topographical characteristics of the mining area, the west section and the Geyangang section are developed by Pingyi-slip well; the east section is developed by the open shaft, and the flat belt and belt conveyor are transported.
For the inclined ore angle greater than 60°, the ore and surrounding rock medium stable ore body, the bottomless shallow hole retaining method is adopted; for the medium thick ore body with the inclination angle of 30°～60°, the upward horizontal layered tailings filling mining method is selected; Fully mining methods are used for moderately stable ore bodies with gentle slopes, ore and surrounding rock. Considering that the surface does not allow collapse, the tailings or waste rock shovel are used to fill the empty area. The technical indicators of the three mining methods are shown in Table 1.
Based on the analysis of the geological conditions of the Zizigou gold ore body, based on the principle of maximizing the use of mineral resources and ensuring the safety of mining operations, it is determined that the bottomless shallow hole remains in the mining method.
2 bottomless column shallow hole mining ore mining method
2.1 Applicable conditions and components of the nuggets
This mining method is suitable for stable ore bodies with an inclination of more than 60°, ore and surrounding rock. The length of the nugget is 50-60m, the width is the thickness of the ore body, the height is the middle section height (40m), the column width is 8m, and the top column is 3m thick, leaving no bottom column. The mining method is shown in Figure 1.
2.2 mining cutting work
From the middle section along the vein lane every 5 ~ 6m excavation and out of the mine, along the vein roadway from the bottom of the ore body about 6m, tunneling the ventilation patio at both ends of the mine, and then dig a 2m × 2m bottom roadway, along the bottom of the mine The bottom roadway can be used as a bottoming space for normal mining operations. For the ore body with higher grade, in order to recover the mine volume of the lower middle section as much as possible, the C20 reinforced concrete false bottom is cemented on the bottom of the cutting lane before the mining, and the thickness is 500mm. The 12mm steel mesh is used, and the steel mesh is 250mm×250mm. The mining and cutting engineering mainly includes: stage transportation roadway, ventilation patio, returning wind river, return air roadway. See Table 2 for the amount of mining and cutting work.
2.3 mining work
The ore is recovered from the bottom space layer by layer, and the layer height is 2.0 to 2.5 m. Use the 7655 type pneumatic rock drill to make horizontal or micro-tilt blastholes, single-sided single-machine drilling, hole depth 1.8m, hole spacing 0.8~1.0m. The blasting uses ammonium fry, artificial charge, and electric detonator detonation. After local mining, security personnel will be in a timely manner and dome. The local mining is 1/3 of the ore deposit, and the remaining 2/3 ore is used as the working platform for the next operation cycle, ensuring that the working face has a working space of 2.0 to 2.5 m. At the end of the mine mining, the mine is finally released.
2.4 stope ventilation
The transportation lanes, the bottom yard and the Shimen alley are ventilated by ventilation system. The working environment of the underground stope is relatively poor. Local ventilation needs to be added. Fresh airflow enters the stope. The wind speed of the working surface must not be lower than 0.15m/s. Go to the upper middle section of the return airway, and finally the wind well discharges the surface.
2.5 stop mining
The mining of the stope is carried out in Sichuan, with partial ore mining and a large amount of ore mining. The partial ore deposit is 1/3 of the ore deposit, and the remaining 2/3 ore is used as the working platform for the next operation cycle, and is temporarily retained in the stope. After the mining of the entire mine is completed, the rock loader or scraper will be discharged.
2.6 pillar recovery
High-grade pillar recovery, low-grade ore body retention permanent pillars are not recycled. Since the reinforced concrete false bottom is laid before the mining stop, the top column can be recovered along with the recovery. When the column is recovered, the patio and the contact road in the column are used to make shallow eyes, and once collapsed, the ore that has collapsed is mined from the bottom of the mine. Due to poor mining conditions, one-time collapse, the recovery rate is 60%.
Filling the gob after 3å—£
At the end of the mining stop, the mining column is returned to the mining column, and a large amount of ore is discharged. Then, the goaf is filled, and the filling is used to dig the waste rock and tailings. Before filling in the goaf, first close the goaf, the quality of the masonry of the closed wall should meet the standard; from the upper middle section, the mine will fill the well every 10~15m into the mine, the specification is 2m×1.5m, and the filling is small. A filling platform is installed on the upper part of the well for filling. Filling the goaf is shown in Figure 2.
4 Conclusion
The shallow hole retention ore mining method has less capital investment, simple production management and large production capacity of the ore block; high recovery rate of filling and mining method, timely filling of the stope empty area, effective control of ground pressure and high mining safety. After technical analysis, combined with the geological occurrence of the Early Zigou gold ore body, based on the principle of maximizing the use of mineral resources and ensuring the safety of mining operations, the final determination of the bottomless shallow hole retention ore mining method is carried out. The mine with high ore grade builds artificial false bottom, maximizes the recovery rate, and processes the goaf well, effectively controlling the ground pressure and creating greater economic benefits for the mine.
Author: Xu Hengpeng; Gansu Province early cooperation ditch gold limited liability company;
Liu Yunqiu; China Iron and Steel Group Maanshan Mine Research Institute Co., Ltd., State Key Laboratory of Metal Mine Safety and Health , Huawei Metal Mineral Resources Recycling National Engineering Research Center Co., Ltd.;
Article source: "Modern Mines"; 2016.5;
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