After a mine open pit mining underground mining, -74m above -50, -62m average water-free pillar sublevel caving.
Because the mine is a thin ore body and its shape is complex, mining with a sub-column sublevel caving method causes large ore depletion and loss. To this end, after analysis and research, the sublevel caving method without bottom column was changed to shallow hole retention method, and the transition was stable and smooth.
1 deposit geological and mining technical conditions
1.1 Deposit geological conditions
The mine body is east-west, and the ore body at the level of -74 ~ -110m shrinks downwards, and gradually becomes larger under -110m. The shape of the ore body is complex and the thickness changes greatly.
The surrounding rock of the ore body is diorite , altered diorite, skarn (stable, relatively stable rock) and kaolin , chlorite, diabase (unsteady solid rock), under the ore body The disk is marble (a stable rock type).
The stability of ore varies with type and structure. Block-rich ferromagnetic magnetite and iron-rich mixed ore are stable ore, honeycomb and loose iron ore are very unstable ore, disseminated iron-poor magnetite and The iron-poor mixed mine has a large change in hardness and is a relatively stable ore.
Mining method above 1.2-74m level
The mine-74m level (see Figure 1) above the -50, -62m level is mined by the bottomless sublevel caving method, and the recovered sections are filled with the cover rock.
The -74m horizontal mine is equipped with transportation communication roadway, inlet wind well, chute and elevator shaft, etc. The mining project in the ore body includes two ore roadways along the ore body, separated by 10m, length 104m, and at the end. The cutting patio was excavated and connected to the return air well; two chutes were arranged on the ventilation corridor. The cross section of the transportation contact roadway, the vein transportation roadway and the mining roadway is 3.6m×3.3m, and the section of the ventilation roadway is 2m×2m.
In the mining approach, medium and deep hole rock drilling, blasting, shovel loading and so on. Medium and deep hole parameters: hole diameter 90mm, 7 holes per row, edge angle 61°, blast hole row distance 1.8m. The BQF-100 charger is equipped with ammonium nitrate explosive, which is detonated by detonating tube, detonator and detonating cord.
1.3-74 ~ -110m horizontal mining conditions
(1) After entering the level of -74m and below, the ore body shrinks, and gradually becomes larger under -110m, with complicated shape and large thickness variation. -74m horizontal main ore body length 104m, -86m horizontal ore body length 86m, -98m horizontal ore body length 65m, -110m horizontal ore body length 54m, thickness variation, minimum thickness 5m, maximum 20m, average 15m, The inclination angle is 80°. According to the bottomless entry distance of 10m, if two approaches are arranged, the ore body is too narrow and the depletion rate is large; if an approach is arranged, the medium and deep holes cannot be completely controlled to the ore body, and resource recovery is difficult.
(2) Each horizontally arranged mining roadway will implement a medium-deep hole project, and the amount of mining engineering will be relatively large.
(3) caving SUBLEVEL high technical requirements of construction method, can lead to improper operation and pushing flap top wall, covering the decentralized rock ore, a high dilution rate and loss rate, ore mining demanding management block.
2 choice of mining methods
According to the ore body shape, the shallow hole retention method was selected and compared with the previous sublevel caving method without bottom column.
(1) Construction technical conditions. There is a sub-column sublevel caving method for every 12m segment, each segment must be digged for transporting alleys and cutting alleys, etc., and the mining workload is large; the shallow hole retaining method is 60m one stage, only at the top of the stage The top column is taken, and the topping treatment is completed after the end of the mining. The bottom bottom structure and the production process are simple. After the bottom structure is formed, the stope is formed quickly, the management is convenient, and the mining quantity is small.
(1) Ore depletion rate and recovery rate. The sublevel caving method without pillars has the cover rock mixing in the later stage of the mining, the depletion gradually increases, and there is also the loss of ore; the shallow hole retention method rock drilling and recovery, the pure mine in the empty field can be extracted, and the mining The field boundary can be controlled in the contact zone of the ore, the ore is less depleted, and the top column is mainly retained in the whole stage, and the loss is small.
The analysis of the main economic and technical indicators of the two mining methods is shown in Table 1.
It can be seen from Table 1 that under the same equipment and technical conditions, the shallow hole retention method is superior to the bottomless sublevel caving method. The whole ore body change is not very large, which is conducive to the ore recovery of the retention method.
3 application of shallow hole retention method
3.1 Transition of mining methods
According to the occurrence conditions of the ore body, in the safe and reliable, the stope layout and the recovery process is simple, the lower loss and depletion, and the principle of using the existing conditions of the mine as much as possible, the shallow hole retention method is adopted for mining. The -74m mining project (except for the cutting patio) has been completed, and the -74m whole inlet and return air system and the ore-leading shaft have been formed during the construction and the cutting trough is completed. The transition plan of the mining method: brush the two columns on both sides of the approach with a shallow hole at -74m level, brush the length of the column at 5~10m at a time, directly recover the inlet column at this level, and then implement the medium-deep hole blasting. From the east to the west, the mining is carried out in turn, and after the end of the level, the shallow hole retention method is used for the recovery below -74 m.
3.2 Structural parameters
The nugget is 60m high, 50-75m long, and the top column is 5m high. The width is the thickness of the ore body. It is flat-bottomed and arranged along the ore body.
3.3 Cutting and cutting engineering layout
In the excavation stage of the mine, the roadway, the ventilation contact road and the slipway contact road are transported. A pedestrian ventilation patio is arranged at both ends of the ore body, and a pedestrian ventilation corridor is arranged on the patio at a distance of 6 m. According to the ore body condition, the ore approach is evenly arranged, and the spacing of the ore approach is 10~15m. After the completion of the approach, the ore body will be drilled along the ore body.
3.4 mining process
After the construction of the bottom structure is completed, the mining is carried out from the bottom to the top along the vein roadway. The one-sided trapezoidal arrangement of the working face is shown in Figure 2. The roof of the stope is arched, which is beneficial to the stability of the roof and the step of the working surface along the rising direction of the wind flow. Improve ventilation. The 7555 rock drill is used to hit the blasthole. The blasthole is parallel to the ore body structure, and the rock solidity coefficient is f=8~12. The blasting parameters are designed as follows: the diameter of the blasthole is 40mm, the minimum resistance line is 0.8m, the row spacing of the blasthole is 1.0~1.2m, the hole spacing is 0.8~1.0m, the blastholes are arranged in a staggered arrangement, and the hole depth is 2. 5m. Using 2# rock explosive, the charge factor is 0.6, and the explosive consumption is 0.25-0.4kg/t. The long disc is used for the upper disc.
At the time of mining, some of the ore is mined in the approach, and about 30% of the ore is removed. The ore is temporarily retained in the mine, so that the working space maintains a mining space of 2.0 to 2.5 m as a drainage flat. When mining back to the top column, a lot of minerals are produced.
After the end of the mining, the goaf collapses the top column or is filled with waste rock.
3.5 Security Technology Management
(1) Roof management. The working face of the stope can be arranged on one side with a trapezoidal shape and constructed into an arch shape, which is conducive to the stability of the roof. During the operation, the monitoring is strengthened. The two are responsible for one drilling rig , one person working and one person monitoring.
(2) Reasonably arranging the bottom structure and the ore approach, the narrower position of the ore body, forming the bottom structure along the ore body, and arranging the ore approach on the extra-pulse contact road; the ore body is located at a wide position and arranged in the middle of the ore body Once through the veins, the ore route is placed on the veins.
(3) Reasonably arrange the mining. After each blasting, ensure that there is enough working space in the stope, and the mine can not deliver too much, and 1/3 of each blasting volume is suitable.
(4) Gob area treatment. The top hole is arranged on the top plate in advance, and after most of the ore in the stope is transported out, the remaining 1/5 is reserved as a cushion layer, and then the topping treatment is performed.
3.6 Economic and technical indicators
The economic and technical indicators for the mining of the two mining methods are shown in Table 2.
4 Conclusion
The mine adopts the shallow hole retention method, which effectively solves the problems in the sub-column sublevel caving mining method, reduces the mining engineering quantity, reduces the ore loss, reduces the mining cost, and improves the economic benefit. Experienced mining of thin ore bodies.
Author: YELLOW; Wuhan Iron and Steel Group, St. open technology limited liability company Ezhou branch;Article source: "Modern Mining": 2016.1;
Copyright:
Cattle Crush,Cow Crush,Mobile Cattle Crush,Livestock Crush
ANPING COWAN WIRE MESH & MACHINES CO., LTD , https://www.cowanfences.com