Research on Mining Technology of Slowly Inclined Thin Ore Body in a Copper Mine

Gently inclined thin ore body occupies a large proportion of metal mines, mining methods common comprehensive mining law, room and pillar, wall caving, wall-filling method [1]. The choice of mining method is directly related to the safety management, production capacity and economic benefits of the mine. In the trial mining stage a copper mine, combined with technical conditions and status of mining engineering, mining method proposed is reasonable, to ensure the safe and efficient mine production.
1 mining technical conditions
A copper deposit occurs in the lower part of the central volcanic-sedimentary metamorphic section (Pt1h14). The ore body is layered and has a phenomenon of expansion and contraction. The ore body is basically consistent with the surrounding rock, and is subject to stratification and lithology. The control is obvious. The ore body is 1080m long along the strike, with a tendency of 445m long, towards EW, inclined to SW, the inclination angle is 15°~26°, and the average thickness is 3.27m, which is a gently inclined thin ore body. Ore chalcopyrite, pyrite most, magnetite, cobaltite, red limonite, the total amount of ore to 3.86 million t, copper 21352.58t, the average copper grade of 0.56% . The associated components in the mining area are mainly cobalt, iron, sulfur, etc. The cobalt-metal reserves of the associated beneficial components are 765.88t, the iron metal reserves are 485184.98t, and the sulfur metal reserves are 51696.90t. The surrounding rock and rock (or inclusions) of the ore body are mainly quartz albite, followed by black cloud (two clouds) quartz schist and a small amount of pomegranate black cloud (two clouds) schist, dolomite quartz schist, local The top of the lot is gabbro and a few porphyry.
The Quaternary loose deposits and weathered and fractured rock masses in the mining area are divided into loose engineering geological rock groups; flaky, thin-layered, medium-thick layered rocks are divided into soft rock groups; thick layered and massive rocks are divided into half. Hard ~ hard rock group. The II, III, IV, and V structural planes are mainly developed in the mining area. According to geological surveys and boreholes, the F1 and F13 fault zones are Grade II structural planes;
The secondary fault is a Grade III structural plane; the bedding, joint fissures and weathering fissures are IV and V structural planes. The types of engineering geological exploration in the mining area belong to the first type (loose) and the third type, which is moderately complex.
The lithology of the stratum is complex, the geological structure is developed, the weathering of the rock mass is strong, the erosion is strong, the weathering fissure is developed, the thickness of the weathering zone is large, and the weak interlayer and fracture zone are generally present, which directly affects the stability of the rock mass. The volcanic-sedimentary metamorphic rocks in the mining area are mainly flaky, thin-layered, medium-thick layered and massive structures, composed of loose rock group, soft rock group, semi-hard group and hard rock group. The physical and mechanical parameters of the ore are shown in Table 1.

The water-bearing space of the main water-filled aquifer in the mining area is characterized by a fissure aquifer (belt), and its exploration type belongs to the second category. The water-filled aquifer (belt) is basically the same body as the ore layer and belongs to direct contact, which is a direct water-filled deposit. The ore body is located above the local minimum erosion datum. The main water-filled aquifers and tectonic fracture zones have weak water content, simple hydrogeological conditions, and their complexity is the first type.
2 mining method selection
Mining methods are directly related to mine safety, production capacity, labor efficiency, depletion and loss of ore, ore mining costs and major economic and technical indicators. Therefore, according to the occurrence factors of the ore body and the mining technical conditions, combined with the actual situation, comprehensive comparison analysis can be used to obtain the optimal plan. The mining plan of this deposit is mainly based on the burial depth of the ore body and the different mining methods of the minerals. The iron mining ore is basically used in the form of open mining. For the deep buried copper ore body, the flat mining and shaft development methods are used to drain the groundwater. The copper mine was initially selected from three mining methods: shallow-hole room-column method, comprehensive mining method, and single-layer caving method.

Through the comparative analysis of the mining capacity, mining ratio, ore loss rate and depletion rate, work class efficiency, material consumption and other indicators (Table 2), it can be concluded that the single-layer caving method is shallower than the shallow hole room column method. The mining method has a slightly larger production capacity, but the loss rate is higher and the mining ratio is larger. The comprehensive mining method and the main economic and technical indicators of the shallow hole room column method are similar, but the shallow hole room column method is more comprehensive than the comprehensive mining method. Higher, the process is more complicated and the cost is higher. The final comparison optimizes the general comprehensive mining method. However, in the trial mining stage, the general comprehensive mining method has a low production capacity and the roof management is difficult, and many roofing accidents have occurred. Therefore, the comprehensive mining method for small mines is proposed (Fig. 1).

The small mining comprehensive mining method has the following characteristics: 1 the mining process and equipment are relatively simple; 2 along the ore body trend, the stage is divided into several regular ore blocks, and the ore blocks are divided into several mining houses, each of which acts as An independent mining unit; 3 in the recovery process, the lean or stone can be used as a pillar; 4 mining efficiency is high, the exposed area of ​​the roof is small, the safety factor is high, and the ground pressure management and ventilation requirements are relatively simple.
3 mining process
3.1 Nugget layout
The ore body is divided along the ore body, and the mine is arranged in a vertical direction [1]. In the inclined direction of the ore body, the mining is divided according to the equipment capacity. The middle section is 30m high, the stope is about 60m long, and the mine is 15m wide. The thickness of the body, the column, the top column and the bottom column are both 2 m.
3.2 Mining and cutting engineering
The middle section of the transportation lane is arranged along the ore body of the ore body [2], and the ore-boring well is drilled every 15m to connect with the cutting roadway and cutting the mountain. The cutting roadway from the stope cuts up the mountain to the mining room, and is connected with the upper stage of the roadway as the free surface of the mining and the ventilation of the stope.
3.3 recovery work
3.3.1 Recovery order
In the stage, the receding mining is adopted, and the mining room is an independent mining unit [3]. The mining work starts from the cutting uphill and moves back from the bottom to the top in the inclined direction of the ore body. The mining room is about 15m ahead. .
3.3.2 Rock drilling and blasting
The YT28 rock drill is used for shallow hole falling, the hole diameter is 34~42mm, the hole depth is 2~2.5m, the row spacing is 0.7~1.0m, the hole spacing is 0.8~1.2m, and the propulsion distance is 2m. The blasthole utilization factor is 65% to 80%. The blasting adopts the manual charging method, the 32mm emulsion explosive is selected, the detonating tube is slightly detonated [4], the orifice is filled with the gun mud, and the filling length is not less than 40cm. The ore block is 400mm and the bulk rate is 6% to 8%.
3.3.3 Ore transport
The 2DPJ-30 electric pick-up winch is equipped with a 0.3m3 comb type bucket, the efficiency is 60-70t/shift, the ore is thrown into the slippery shaft, and the ore-boring slipper is put into the electric motor car and transported to the surface.
3.4 ventilation
The stope adopts FBD4.5/2×5.5 type local ventilator for natural ventilation, and the electric shovel driver is located on the windward side of the wind flow. No mining work is carried out until the ventilation system is formed in the stope. In the inlet airflow of the mining face, the oxygen is not less than 20%, the carbon dioxide is not higher than 0.5%, and the dust content of the mining face is not more than 0.5mg/m3. After the mining of the stope, all the roadways connected to the goaf shall be closed in time to ensure the full utilization of downhole wind flow. The wind flow is for transporting alleys - cutting alleys - mining yards - washing work surface - mining room cutting up the mountain - the upper stage returning wind alley.
3.5 Roof management and goaf processing
Carry out regular monitoring work in the mining area, record raw data, and formulate emergency treatment measures. Persist in knocking on the top of the question, clearing the pumice stone , eliminating the "three violations" phenomenon, and keeping track record and shifting records between the teams.

The partial fracture zone adopts the anchor metal mesh as the temporary support, the mesh degree is 1.5m×2m, the anchor length is 2m, and the anchor hole diameter is 28-30mm. After the mining block is finished, the pillars are recovered and the goaf is finally closed.
4 major economic and technical indicators
Although the small mining room comprehensive mining method has increased the mining block cutting ratio, it has reduced the difficulty of roof management and improved the safety factor of the stope. At the same time, the production capacity of the ore block has increased by about 3 times. The main economic and technical indicators are shown in Table 3.

5 Conclusion
Combined with the mining technical conditions of a mine, the mining technology research on the gently inclined thin ore body of the copper mine, using the small mining room comprehensive mining method, achieved the effect of roof management, reduced the occurrence of roofing accidents and improved the production capacity of the mining block. Improve the working environment. Due to the complex and variable mining environment, on-site ground pressure monitoring and mining depletion rate and loss rate supervision should be strengthened to achieve safe and efficient targets.
references
[1] Wang Yunmin. Modern Mining Handbook: Volume [M]. Beijing: Metallurgical Industry Press, 2012.
[2] Chen Guoshan. Metal mining underground mining [M]. Beijing: Metallurgical Industry Press, 2012.
[3] Wang Qing, Shi Weixiang. Mining science [M]. Beijing: Metallurgical Industry Press, 2001.
[4] Jie Shijun. Underground mining of metal deposits [M]. Beijing: Metallurgical Industry Press, 1992.
Article source: "Modern Mining": 2016.10;
Author: Wang Wei; Liangshan Mining Company Limited;
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