Application of Upward Horizontal Layered Tailings Cement Filling Method in Shidun Iron Mine

Pacific Mining Co., Ltd. administered pier iron mine in Yangtze Bank, mining area of four inflection points of coordinates, mining area 0.2862m2, most ore angle 10 ° ~ 15 °, part of the ore body tilt angle
40° or so. The grade of the ore is high, and the average grade of TFe is about 46%. The grade is relatively stable, and the distribution is even and the recovery value is large. However, the geological conditions are relatively complicated, and the amount of water inflow is large. The groundwater in the mining area is seepage in the form of underground turbulence. The total flow direction is from south to north, and the flow direction of the Yangtze River is consistent in this area. The slope of the groundwater level is small, and all kinds of aquifers in the mining area are There are varying degrees of hydraulic connections. There are villages, farmland, highways, etc. near the mining area, and the surface is not allowed to fall. In order to recover more ore and maintain the balance of ground pressure, according to the mining conditions, it is urgent to choose a mining method with high recovery rate, ensuring that the surface of the mining area does not fall, and protecting the ecological balance of the surface.
1 mining plan
The scale of mine construction is 200,000 t/a, and the total service life of the mine is 10 years, of which the production period is 1a (including the infrastructure period of 1.0a), the production period is reduced by 1a, and the stable production period is 8a.

Underground mining is used. In the ore body trend, from the east to the west retreat mining; in the ore mining from bottom to top, the first mining -185m middle section.
2 mining method selection
2.1 Mining method selection principle
1 production safety, good working conditions and environment; 2 adaptability and flexibility, can adapt to changes in ore body shape; 3 large production capacity, high efficiency; 4 loss rate of depletion; 5 advanced technology, simple and reliable process 6 is conducive to ground pressure management, can ensure that the mining area does not penetrate the Quaternary aquifer; 7 less energy consumption, low cost, low investment, good economic benefits; 8 small amount of mining and cutting, short construction time, fast production.
2.2 Influencing factors of mining method selection
(1) Geological factors of the deposit. The main ore body in the mining area is buried 50-188m, which is a contact-reversing-hydrothermal iron deposit mainly composed of a concealed hydrothermal filling. The surrounding rocks of the ore body are mostly marble , calcite and diorite , some of which are Angular rocks, a small amount of breccia and anesite. Under the influence of comprehensive factors such as groundwater pressure, the stability of engineering geological conditions is poor and the damage is outstanding.
(2) Hydrogeological factors. Quaternary buried region is thick, strong water-rich; deeply buried deposits, ore and of roof-rich aqueous layer in ~ strong, direct inlet roadway, large pressure; fractured karst aquifer aqueous Quaternary Although the weakly permeable rock layer with thickness of 0~26m between the layers plays a role of relative water blocking, it is often the Quaternary strong aquifer and fissure in the structural fissure, the development of the fracture zone of the rock mass contact zone or the thinning and extinction of the layer. The favorable channel for the communication of karst aquifers is serious in the future roadway. The deposit belongs to the roof directly into the water and has a stable source of groundwater recharge, so its hydrogeological conditions are complex types.
(3) Others. The surface of the mining area is mostly farmland and villages. Local roads pass through the surface movement range, and the surface is not allowed to fall.
2.3 Comparison of mining methods
According to the ore body occurrence characteristics, mining technical conditions and hydrogeological conditions of the Shidun iron deposit, especially the mining area is located in the plain, the surface is mostly fertile, and the surface is not allowed to fall. The filling mining method and the empty field mining method are selected. . A comparison of the two mining methods is shown in Table 1.

Mining with trackless transport equipment (scraper). Through comparative analysis, the upper horizontal stratified tailings filling method is selected for mining. The mining method has the advantages of high recovery rate, high degree of mechanization, large capacity of the ore block, and high labor productivity.

3Upward horizontal layered tailings cement filling mining method
3.1 Mining method components
The ore blocks are arranged along the ore body. According to the stability of the ore and the occurrence conditions of the ore body, the width of the ore block is 6-8 m, the length of the nugget is 50 m, and the exposed area of ​​the roof of a single stop is controlled below 400 m2. The height of the nugget is 50m in the middle section, 6m in the column, and 5m in the bottom column, without leaving the top column.
3.2 mining cutting
The mining projects mainly include extra-vehicle transport lanes, loading and transporting veins, pedestrian ventilation patios, contact roads, ore chutes, filling and returning wells, etc.; cutting projects have cutting lanes.
Firstly, the extra-vehicle transport roadway (2.4m×2.6m) was constructed, and the ore-penetrating vein (2.1m×2.2m) was drilled in the direction of the vertical ore body. The mine is drilled through the veins (2.0m) to the upper side of the bottom column, and the upper layer is made of steel chutes that are erected along the road. For the flat bottom structure, the cutting lane (1.8m × 2.0m) is applied to the two wings on the bottom column to the design position, and cut to the upper disc boundary of the ore body. In the cutting alley, close to the inter-column, the pedestrian ventilation patio (1.8m × 2.0m), and the tunnel connection (1.8m × 2.0m) to the mine.
Each mine block is equipped with a return air well, a erected ore sluice well and a pedestrian venting patio. The upper and horizontal stratified tailings cementing filling method is shown in Table 2. The mining method is shown in Figure 1.

The mining cut ratio is 13.92m/kt (standard m), and the by-product ore rate is 13.0%.
3.3 recovery work
3.3.1 Distribution of ore mining
The ore yield of mine by-product is 13.0%, and the production distribution when the production capacity reaches 200,000 t/a is shown in Table 3.

The mining cut ratio is 13.92m/kt (standard m), and the by-product ore rate is 13.0%.
3.3.2 Mining process
The mining process mainly includes rock drilling, blasting, ventilation, mining, flat field and filling [1].
3.3.2.1 Rock drilling and blasting
The YT-28 pneumatic rock drill is used for shallow hole drilling, with a hole diameter of 42 mm, a hole depth of 2.5 m, a hole spacing of 1.2 m and a row spacing of 1.0 m. The blast hole collapse amount is 1.6t/m, the rock drill machine shift efficiency is 40m, and the annual operation rate of the rock drill is 60%. It is calculated that each mine block needs to be equipped with one YT-28 rock drill, which requires a total of six.
Employing explosives and manual charging are used for secondary crushing of block ore with a size larger than 400mm by manual or blasting [2].
See Table 4 for the calculation of the upward-level horizontal tailings cementing filling method.

Taking into account the loss of mining dead angles in the stope and the irregular mining of the ore body and the loss of the mine body, the actual recovery rate of the underground ore is slightly less than 95%. In addition, due to the fact that the pillars in actual production are recovered as appropriate, the depletion rate will also decrease. After calculation, when the mine reaches 200,000 t/a, the main mining equipment is shown in Table 5. The main materials used for recovery are shown in Table 6.

3.3.2.2 Stope transport and mining

A 2JPB electric raft is required for each stope, and a total of 6 units are required. The ore produced in the stope is loaded into the 1.5m3 mine car by electric raft, and the ore is directly upgraded.
3.3.2.3 Mine column recovery
The design has a 5m high bottom column (rock) and a 6m wide column. After the mining work of all the mines in the middle section is completed, the upward horizontal layered tailings cementing filling method is adopted for the column recovery.

3.3.2.4 Roof management and goaf processing

(1) Roof management. After 40 minutes of blasting in the stope, the miner will carry out the top of the mane and check it safely to ensure safe operation in the stope. For lots of local unstable roof design uses bolt or anchor network for support, take bolt and metal mesh combined support when necessary, Arching support for lots of rocks and broken.
(2) Empty area management. The empty area is filled by tailings cement filling method to maintain the ground pressure balance.
3.4 filling
The filling material is the whole tailings after grinding in the plant (prepared for construction), and the insufficient part is supplemented by river sand and waste rock. The cementitious material is selected from ordinary Portland cement or slag cement with a strength class of 42.5. After the mining site is finished, the silt mine is cleaned and the filling pipeline is erected.
Filled with tailings cement, the ratio of sand to sand is 1:6～1:8, the filling pipe is laid on the central courtyard, and the water discharge is discharged into the middle roadway by the steel structure drainage well. The drainage well is made of 1500mm and 8mm thick steel plate, the hole of the cylinder wall is 25mm, and the outer surface is covered with linen. The filling system is shown in Figure 2.

3.5 stope ventilation
YBT-5.5 and YBT-11 local fan ventilation are adopted in the stope. After each blasting, fresh airflow enters the working face of the stope. The dirty wind is discharged through the pedestrian patio and the upper filling back to the wind well. After the ventilation is about 40 minutes, the mine safety is completed. The staff will test the toxic gas on the stope and the face, and the operator can enter the stop operation after reaching the standard.
4 technical economic analysis
The economic indicators of mining technology are shown in Table 7.

Through the economic analysis of mining technology, the filling mining method has the advantages of high ore recovery rate, low depletion rate, effective control of ground pressure, high mining safety, high comprehensive utilization rate, reduced tailings stockpiling and land occupation, and ensuring surface ecological balance. . In addition, due to the use of trackless transport equipment (scraper) for mining, the upward horizontal layered tailings filling method mining also has the advantages of high recovery rate, high degree of mechanization, large capacity of the ore block, and high labor productivity.
5 Conclusion
Through the economic analysis of mining technology and the integration of various factors, the Shidun Iron Mine uses the upward horizontal cementation filling mining method for mining. It not only solves the problems that the surface is not allowed to collapse, does not allow pollution, but also has strong safety, and the economic and social benefits are more significant.
references
[1] Lv Zhiwen, Liu Yunqiu. Application of upward horizontal layered cementation filling method in Dongji Gold Mine [J]. Modern Mining, 2016 (5): 32-33.
[2] Wang Yunmin. China Mining Equipment Handbook: Volume [M]. Beijing: Science Press, 2007.
Article source: "Modern Mining"; 2016.9;
Author: Lee first month, Nanjing Hydraulic Research Institute;
Liu Yunqiu , Wu Fei; China National Iron and Steel Group Maanshan Mine Research Institute Co., Ltd., State Key Laboratory of Safety and Health of Metal Mines , National Engineering Research Center Co., Ltd., Huawei Metal Mineral Resources Recycling;
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