Application of Pre-controlled Top Segment Filling Mining Method in a Gold Mine
The geological conditions of this type of ore body are complex, with multiple mining difficulties and unfavorable factors, and the gently inclined medium-thickness and thick and unstable deposits with high mining value have been the problem of mining at home and abroad [1-5]. To this end, this paper mainly studies the new mining methods based on the review of the original mining methods.
1 original mining method
The gold ore is mainly used to fill the layered tailings (cement) in the mechanized panel [6], as shown in Figure 1. The one-step stope and the two-step stope are staggered. The overall mining principle is to first pick up the middle section of the middle (sub-section) section, and then successively recover the two sides, so that the distribution of the entire middle section of the stope is upwardly arched to improve the overall stability of the middle section.
1.1 stope structure parameters
When the thickness of the ore body is not large, the mine is arranged along the ore body; when the thickness of the ore body is thick, the vertical ore body of the mine is oriented, the length of the mine is the horizontal thickness of the ore body, and the mining room is divided into two steps, one step and The width of the two-step mining area is 8m and 7m respectively. Each middle section is divided into 5 sections, the section height is 10m, and the height of each mining is 3.3~3.4m. After the mining, the reinforced concrete false bottom is constructed on the bottom plate, and the thickness of the top column is 3.0-6.0 m. After the end of the mining stop in the middle section, the concentrated mining is carried out.
1.2 mining engineering layout
(1) The outer section of the lower disc is a quarter-center arch of 5.05m×3.55m with a turning radius of 8m. The sectioned alleys are arranged outside the lower disc, about 40m away from the lower boundary of the ore body to meet the needs of the scraper climbing.
(2) The contact roadway of the stope is 1/3m three-heart arch of 3.6m×3.15m, the turning radius is 8m, and the section of the connecting section and the ore body are connected. The center line of the stopway lane coincides with the centerline of the stope.
(3) Filling the return air patio is a 1/3 three-heart arch of 2m×2m. Each stope is provided with a filling return air patio, which is digged from the lower middle section to the upper middle section and penetrates with the upper middle section of the upper section. The inclination angle of the filling return air patio is about 43°.
1.3 mining process
The rock drilling method, which is mainly based on rock drilling rigs and supplemented by the 7655 air-leg rock drill, is horizontally advanced from the lower part of the ore body (excluding the approach method). The falling ore eye adopts the plum-shaped cloth hole, the row spacing is 0.6-0.7m, the hole spacing is 0.7-0.9m, the distance between the top plate controlled explosion eye row is not more than 0.5m, and the hole spacing is not more than 0.7m. . The 2# rock emulsion explosive is used, and the non-conducting detonator is slightly detonated. Both the falling ore and the control eye are treated with a spacer, and each hole has two detonating detonators of the same section.
1.4 There is a problem
The advantage of this method is that the cutting and mining engineering layout is flexible, because the column is not left, the ore loss rate and the depletion rate are low, and it is beneficial to the ground pressure management. However, due to the large thickness of the main mining body and the gentle inclination of the ore body, with the one-step mining site, the safety problem of the two-step mining column appears to be localized, and local stress concentration and destruction occur; the low-strength filling body on both sides of the second-stage mining field It may not be enough to support the overburden stress of the two-step pillar and the filling body damage occurs. At the same time, in order to further increase the mining strength of the deep middle section of the ore body [7], it is necessary to innovate the mining method of the original two-step stope, explore suitable mining methods, and improve the production capacity of the deep middle section.
2 Overview of new mining methods
2.1 Pre-controlled top section filling mining method
According to the technical conditions of mining and combined with the defects of the original mining method, the pre-control top section filling mining method was developed and field test was carried out, as shown in Figure 2. The process is: digging a medium-deep hole rock drilling and discharging roadway (3.2m×3.1m) in a middle section of the test stop, and simultaneously excavating the pre-controlled top roadway (3.2m×3.2m) in the upper section, and then Expanded, the roof is made of resin anchor + steel strip + shotcrete combined support, and the cutting patio (2.2m × 2.2m) is drilled on the upper part of the ore body, and the upper section is exposed along the whole section of the patio, with resin anchor + steel With the + shotcrete combined support on the upper rock formation, the pre-control top project is completed. Drilling and excavation roadways are drilled to the middle and deep holes, and from the upper plate to the lower plate, the mine collapses, and each time the mine collapses 2 to 3 rows. The collapsed ore is transported out through the lower section of the roadway with a scraper. Fill the gob area once. The length of the stope is about 110m, the width is 7m, and the segment height is 10m.
2.2 Recovery order
The cutting groove above the test stop is a free surface, the middle and deep holes fall into the ore, and the back plate is retracted from the upper plate. After the mining of the upper ore body, according to the exposure of the filling body on both sides of the stope and the stability of the stope, the second-step ore column is mined by the medium-deep hole ore mining method. If the stability of the stope is good, continue to use the deep hole. If the stability of the stope is poor, the stope will be closed, and the goaf of the upper plate will be filled and then the same method will be used to mine the ore body.
2.3 Stope pre-control top support technology
The resin anchor rod + steel strip + shotcrete + column combined support is adopted. The surrounding rock of the upper part of the stope is made of resin anchor + suspended steel mesh + shotcrete combined support.
2.3.1 Resin anchor
The anchor rod is arranged in a plum blossom shape with a length of 2.5 m and a spacing of 1.5 m. Uniform use of 25MnSi rebar anchors, diameter 20mm, thread must use thread rolling; anchor tray is made of 8mm thick iron plate, tray is (length × width × thickness) 100mm × 100mm × 8mm; resin anchoring agent model is K2535 And Z2360, the resin roll length is 350-600mm and the diameter is 28mm.
Resin anchor construction method: use MQT-130 pneumatic anchor rig to drill anchor hole, anchor hole diameter 32mm, hole length 2.4m, drilling deviation does not exceed ±0.3m; first volume is placed in the hole during installation K2535 type resin anchoring agent, then put a roll of Z2360 resin anchoring agent, use the anchor rod body to gently push the anchoring agent into the bottom of the hole and then rotate the drilling machine to continuously stir the medicine roll, the stirring time is (30±5) s; After the anchoring agent is stirred for 15 minutes, the steel strip and the pallet are installed.
2.3.2 Shotcrete support
After the resin bolt was used to support and hang the net, 50 mm thick concrete was sprayed. Shotcrete technical requirements: the mass ratio of cement to gravel is (1:4) ~ (1:4.5), the water-cement ratio is 0.4-0.45, and the amount of crushed stone is 30% of the total mass of sand and gravel~ 40%; cement is ordinary Portland cement not less than 325#, sand is hard and clean medium sand or coarse sand, gravel is hard pebbles or gravel with particle diameter not more than 15mm; rock face should be cleaned before spraying, The water-cement ratio should be strictly controlled in the spraying operation; the first layer should be sprayed to a thickness of 2 to 3 cm, and the spraying of the next layer should be carried out after the final layer of concrete is finally set. When the interval is more than 2 hours, the surface of the concrete should be sprayed with water first. The spray thickness is 4 to 5 cm, the rebound rate should not exceed 25%, and the minimum strength of the design concrete is not less than 15 MPa.
2.3.3 hydraulic prop
During the construction of the pre-control top and the completion of the construction, the hydraulic support column is used to temporarily support the pre-control top plate. The model is DW35-200/100 external injection hydraulic prop, the maximum support length is 3500mm, and the maximum bearing capacity is 20t. The hydraulic props are 0.5m away from the side of the stope and the spacing is 3m. When installing, the shoes must be worn with shoes and the top and bottom are respectively placed with wooden boards or steel backing plates to ensure uniform force and prevent the pillars from slipping.
2.3.4 Steel strip and steel mesh
It is cut and welded with A3 steel bar with a diameter of 10mm. The steel has a width of 65mm and a length of 1500, 2900 and 4200mm. It is made of two parallel steel bars welded with the same diameter every 200mm. The steel mesh is suspended while the resin anchor is installed. The metal mesh is made of iron wire with a diameter of 8 mm, and the woven mesh is 100 mm×100.
Mm, the size of a single metal mesh is 2600mm × 1400mm.
2.4 mining process
(1) Rock drilling. The KQD70 medium-deep hole drilling rig is used for rock drilling. The diameter of the drill bit is 65mm, the diameter of the blasthole is 70mm, the row spacing of the medium-deep hole groove is 1.0m, the spacing is 1.5m, and the row spacing of the falling mine hole is 1. 4m, the spacing is 2.1m; pre-splitting blasting is adopted around the stope, the pre-split hole is arranged at the stope boundary, the blast hole spacing is 0.7m; the falling hole adjacent to the pre-cracking hole is the buffer hole, and the buffer hole and the pre-cracking hole are spaced. When the groove is pulled, it is 0.8m; the falling hole is super deep 0.5m, and the pre-crack is 0.8m deep. Since the sides of the ore body are filled, the middle and deep holes should be carefully recorded through the filling body during the rock drilling process, in order to better design the blasting charge. After the completion of the medium-deep hole drilling, the acceptance shall be carried out. If the minimum resistance line of the drilling hole is found to be inconsistent with the design or there is a new geological structure, the dosage and the charging structure should be readjusted.
(2) Blasting. Use modified ammonium explosives or 2# rock emulsion explosives to blast, artificially charge, blast 6 to 8 rows each time, and start mining backwards from the upper part of the ore body. The non-electrical millisecond difference detonator is used, and the double detonation system is detonated.
(3) Mining. The TORO-301D diesel scraper is used for mining. The scraper loads the ore into the pit and the truck is transported to the middle section through the ramp.
(4) Filling. After the end of the whole section mining, the filling wall is filled in the excavation roadway to fill the stope. Artificial false bottoms must be poured with concrete before filling. The false bottom is used as the lower middle section to construct the artificial false roof, and the reinforced concrete false bottom thickness is 0.6m. The steel mesh has main and auxiliary points. The main rib has a diameter of 14 mm, the mesh has a diameter of 1 m×1 m, the secondary rib has a diameter of 10 to 12 mm, and the mesh has a mesh of 0.3 m×0.3 m. The intersection is fixed with a thin wire. The steel mesh is 0.1-0.2m from the bottom plate, and the concrete ratio is cement: medium coarse sand: gravel = 1:3:5, that is, 200,250,750 concrete per cubic meter of concrete, water, cement, sand and stone are respectively , 1250kg. After the concrete false bottom is completed, it is filled with graded tailings, and the ratio of sand to sand is 1:4.
3 conclusions
After on-site trials, the production capacity of the pre-controlled top-segment filling mining method can reach 506.9t/d, the mining efficiency is 121t/work, the depletion rate and loss rate of the stope are 5%, and the mining ratio is 11. 65m / kt, achieved good application results. Practice has proved that the pre-control top support technology is feasible and economical, can ensure the safety and stability of the stope, avoid the destruction of the ore body during the mining of the two-step stope, and realize the safe and efficient mining of the ore body by using the medium-deep hole ore. It has certain guiding significance for the mining of similar gently inclined medium thick and thick and unstable solid ore bodies.
references
[1] Wang Yan, Yuan Yongzhong, Wang Fang, et al. Experimental study on mining method of gently inclined thin ore body [J]. Gold, 2013, 34 (4): 36-40.
[2] Yin Shenghua, Wu Aixiang. Current status and development trend of gently inclined medium-thick ore mining method [J]. Metal Mine, 2007 (12): 10-13.
[3] Cui Yuzhong. Study on mining method of moderately thick and above gently inclined ore body in an iron mine [J]. Metal Mine, 2012 (8): 21-24.
[4] Sun Hongsheng. Application of shallow hole retention method in gently inclined medium thick ore body [J]. Metal Mine, 2006 (9): 29-33.
[5] Wan Jilong, Zhang Hongbo, Xu Yanhui. Experimental study on long-wall controlled explosion continuous mining method in the step-by-step stage of the Minnan Gold Mine [J]. Nonferrous Mining and Metallurgy, 2014, 30(3): 12-14.
[6] Xu Kaimin. Study on support parameters and mining sequence optimization of deep stope in Xincheng Gold Mine [D]. Qingdao: Shandong University of Science and Technology, 2011.
[7] Xu Dong, Hu Zhongqiang. Research and application of medium-deep hole mining method in Xincheng gold mine [J]. Gold Science and Technology, 2010, 18 (5): 72-75.
Author of the article: in adult phase, Hou Xiang, Lei Fan fly; Changchun Gold Design Institute;
Article source: "Modern Mines"; 2016.5;
Copyright:
Steel Drag Chain,Metal Drag Chain,CNC Metal Cable,Iron Cable Drag Chain
Wuxi Yacai Precision Machinery Co., Ltd , https://www.yacaijm.com