Improvement of the mining process of extremely unstable rock mass loose ore body

1 deposit characteristics and ore type

Hunan Shuikoushan BEIFANG copper ore deposit is a famous bronze drum pond small and concealed copper-rich uranium deposits associated uranium, silver elements by Ⅱ, Ⅳ, Ⅴ, Ⅵ four ore body. The mining area is located in the transition zone between the southern margin of the Hengyang Basin and the Upper Paleozoic uplift, and the east-west basement fault zone of the Fuyang-Shuikou Mountain. It is located at the junction of the northern end of the Xiangyang-Linwu north-south tectonic belt and the Xinhuaxia tectonic system. The structure is very complicated and the fault is complex. The folds are very developed, and there are common fault muds and broken breccia structures. The No. VI ore body is the largest ore body in the ore section. It is located in the southeast of the No. II ore body and is strictly controlled by the east-west F22 fault. Orebodies F22 fault on the disc pot days carboniferous carbonate group configuration and Permian coal bucket ridge line group shale and sand disc, ore depth 155 ~ 230m, ore body length of 250m, the extension The depth is 140m, the maximum thickness is 26.61m, the average thickness is 7.76m, the ore body tends to be 200°, the inclination angle is 10°～30°, the ore body is irregular lenticular and lenticular, and common branches and expansion Less phenomenon. The average grade of ore body is Cu6.18%, Ag104.10g/t.
The main structure of the ore is mainly his granular shape, followed by the metamorphic residual structure, tuberculous structure, leaf-like structure and inclusion structure. The ore structure is dominated by dense blocks, followed by breccia, veins, disseminated, layered and the like. The natural type of ore is more complicated. The upper part of the ore section (above -40m elevation) has a high degree of oxidation, and the representative mineral is malachite; the middle part (-40~-70m elevation) is a mixed ore, mainly malachite and chalcopyrite; the lower part (below -70m elevation) It is mainly composed of sulfide ore and its representative mineral is chalcopyrite.
2 status analysis
The Baifang Copper Mine has a mining history of nearly 50 years.
The main ore bodies are II, IV, V, VI and Liujiawan ore bodies. At present, except for the larger ore reserves of the VI ore body in the eighth middle section, the remaining ore bodies have been mined and the mineral resources have been nearly exhausted. The upper part of the VI ore body is composed of red mudstone, sandstone and breccia, and the lower plate is composed of carbonaceous rock and limestone. It has been used in the upward horizontal layered cementation filling method and the downward stratified approach cementation filling method. High grade ore from the bottom of the middle section to below one layer. At present, the unexploited part of the VI ore body above the upper eighth layer is about 28,000 tons, showing east-west trend, the ore body inclination angle is 10°~30°, the ore body thickness is 1~8m, the ore body and surrounding rock are not stable, and the pores are unstable. The water is relatively developed, and it is easy to form a debris flow. The roof management is difficult during the operation, and the roadway or the mining road needs to be supported by the wooden frame, which results in high production cost and greatly affects the operation efficiency. Because the ore body is a muddy ore body with a large content, the mudslide phenomenon occurs whenever the roadway is digging into a lot of water flow, which makes the mining unable to continue, which brings great safety hazards to the production. In order to overcome these difficulties, the mine uses cement grouting to block the water and strengthen the surrounding rock, and the effect is not satisfactory.
3 traditional process analysis
3.1 Mining methods
Since 1972, the mine has promoted the use of up- or down-level horizontal layered cement filling mining methods. It is currently the main mining method for mines, and the caving method is only used for the recovery of residual ore from unfilled systems.
According to the stability of the ore, the standard of the upper horizontal stratified cement filling mining method is generally (2.0 ~ 2.5) m × (2.0 ~ 3.0) m, the length of the road is 10 ~ 30m, the slope is about 10°. According to the dip angle and thickness of the ore body, the approach is arranged in two cases: when the inclination angle of the ore body is less than 30° and the thickness is greater than 15m, the stope is arranged vertically; when the inclination angle of the ore body is greater than 30° and the thickness is less than 15m, The field is arranged along the strike. The stope can be arranged on one side or on both sides.
The mining sequence is as follows: firstly, the bottom of the ore body is pulled down, the ore system, the ventilation system and the pedestrian passage are arranged, and then the mining is carried out one by one from the stope, and each road is filled after the end of the road, and finally one point is taken. After all the layers of ore bodies have been produced, they are transferred to the previous layer for mining.
Upward approach horizontal layered cement filling mining method advantages:
(1) The roadway is recovered, the exposed area of ​​the roof is small, the exposure time is short, and the safety of the mining operation is easy to guarantee;
(2) The specification and direction of the roadway are flexible and adaptable to the complex and variable ore body of the mine, so the depletion and loss indicators are low;
(3) The way out of the mine is relatively fast, the return air is faster, and the dirty wind can be discharged faster, so a working cycle takes a relatively short time.
Upward approach horizontal layered cement filling mining method for the relatively soft ore, its advantages can not be better reflected, mining access needs timely support, support materials consumption is more, making mining efficiency and mining benefits are greatly Lowering is not conducive to the development of mining enterprises.
The downward approach horizontal stratified cementation filling mining method is similar to the upward approach horizontal stratified cementation filling mining method, except that it is firstly extracted from the roof of the ore body to the bottom of the ore body, and its advantages are not only the upward approach but also the upward approach. In addition to the advantages of the horizontal layered cement filling mining method, the top plate is easier to manage than the upward-oriented horizontal layered cement filling mining method, but its pre-mining cost is higher, and the first layer has more support per approach. And each layer needs to dig into the main electric ramp, and the amount of engineering is large.
3.2 Roadway excavation support
The main transport roadway of Baifang Copper Mine is supported by concrete rafting and anchoring, while some roadways or stope roads are supported by wood and I-beam. Due to the complex geological conditions of the ore body, unstable ore and frequent ground pressure activities, when many wells are constructed to the extremely unstable area of ​​the surrounding rock, the surrounding rock of the roof appears to fall down while the construction side is coming, bringing the pole to the operation. A big security threat.
4 process improvement
4.1 Improvement of treatment process in the reclamation area
In the tunneling of the roadway or the roadway of the stope, in the area where the loose surrounding rock is easy to fall, the pneumatic foot drill is used to make the front support of the seamless steel pipe to the top of the crotch area for the advanced support (as shown in Figure 1). Show), forming a row of steel pipe compression layer to withstand the roof pressure of the roadway, and then dig forward. For every 0.5 to 1.0 m of excavation, use ordinary wooden frame or I-beam to support under the pressure-resistant layer of the steel pipe dart. In this cycle, a stable and safe roadway is formed.

4.2 Improvement of mining methods
The reason why the weak ore body is difficult to mine is that the surrounding rock is soft and broken, the roadway is easy to be deformed, and the amount of support for the timber is relatively large. The manual handling of the supporting materials takes more time. In response to this situation, by improving the mining process, this difficulty can be overcome, not only can save most of the support materials, but also improve the work schedule and the safety factor of the stope.
This improvement is mainly through the use of the dislocation down-way layered cementation filling method (as shown in Figure 2), with two layers of mining as a cycle, first cutting the miners out of the ore body to the roof of the ore body. Then, the n-1# approach is applied to the roof of the ore body, and the ramp is filled, and then the approach is taken. Secondly, the misplaced mining n layer and n1 layered ore body, the mining sequence is the first mining n-1# approach, then the n1-1# approach; after the n1-1# approach is completed, then go to n-2 #入路采; n-2# After the road is finished, the n1-2# approach is adopted, so that the alternate arrangement of the way makes the top layer of the next layered road and one side form a solid filling on both sides, forming a relatively stable Artificial surrounding rock, the artificial surrounding rock reduces the amount of access support, provides a safe and stable working environment for the mining of the lower ore body, and so on to the completion of the two layers of mining. Finally, according to this method, the next cycle is sequentially taken until no mine is available.
4.3 improved effect
The improved mining method can share one miner's electric ramp for each two layers, reduce the amount of cutting work, save the cost of mine road support, reduce the amount of stratified road support and increase mining operations. The surface safety factor improves the efficiency of mining work.
5 Conclusion
After this improvement, from the mining situation of several stopes in the middle of the eight sections, the mining recovery rate reached more than 96%, and achieved good mining economic technical indicators. It shows that this improvement measure is feasible and feasible, and the ideal result is achieved in the broken soft section of the mine area. Firstly, the working environment of the stope in the middle and middle sections was improved, and the safety factor of the working face was improved. Secondly, the amount of electric tunnel excavation was reduced, the working time of the mining was increased, and finally the lithology was soft, the support engineering was reduced, and the consumption of materials was greatly reduced. , creating considerable economic benefits.
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