Practice of mining small ore bodies in Fengshan Copper Mine

Fengshan Copper Mine is a medium-sized mining 40 years old mines, underground mining points south, the northern margin belt in two parts, the scale of production in mining mineral stone more than 80 million t, main products are copper concentrate, molybdenum concentrate.
After years of continuous mining, the disappearance of open-air production, the resources available in the shallow part of the mine have been exhausted. The ore body in the southern margin of the well is gradually decreasing with the deepening of the mining depth, and the ore grade is gradually decreasing.
As of July 2013, the geological deposits in the middle section of the South Rim-320m are only 1.31 million tons, of which the main ore body in the southern margin is only 600,000 tons. The main remaining is the edge and the lower part of the small ore body. The lack of mineral resources in the southern margin has become a bottleneck restricting the sustainable development of the mine. Therefore, it is urgent to find out and reasonably recover the resource reserves of scattered small ore bodies in the southern margin to make up for the shortage of production in the southern margin, ensure the balance of the production of the ore belts in the southern and northern margins, and meet the needs of the mine's recent production.
1Geological overview of scattered ore bodies The Fengshan copper deposit is distributed around the granodiorite porphyry body. The ore bodies are mainly distributed in the contact zone between the southern margin of the rock mass, the northern margin and the Daye Formation limestone. It is divided into the southern margin belt and the northern margin belt. To the east of the south edge of the +10 line and to the east of the 6th line of the northern margin are the detonation breccia areas. The lithology is complex in the area, and the marble , skarn and granodiorite porphyry are abundant. The ore body formed by contact and metamorphism After the blasting action is destroyed, many sporadic small ore bodies are formed. The exploration engineering network during the geological survey period was sparse, and many small ore bodies failed to control. Most of the ore body orientation is consistent with the direction of the main ore body or the main contact zone, and the thickness ranges from a few meters to more than ten meters. The shape of the ore body is mostly lenticular, small ore, small ore and small veins. The distribution of ore bodies is disorderly, some occur near the contact zone on the upper or lower body of the main ore body; or occur at the intersection of the inverted rock branch and the main rock mass; some occur in the lower and upward intrusion of the rock branch and the main rock mass Semi-closed structures formed by rendezvous; some occur near the contact zone between marble and igneous rock away from the main ore body, and in the broken breccia. The ore types are mainly copper-bearing skarn, copper-bearing marble, copper-bearing breccia and copper-bearing igneous rock.
The amount of copper metal ore geological survey small number of gold exploration period is eligible for 24355t, average grade of 0.846%; molybdenum metal in an amount of 174.4t, average grade of 0.016%. The amount of copper metal in the unnumbered small ore body is 3,408 tons, and the average grade is 1.24%. Most of the ore bodies seen are one hole, and the extension and extension of most small ore bodies are not controlled.
2 Selection of mining methods 2.1 Roadway shallow hole diffuse mining method Roadway shallow hole expansion and pressure mining method (see Figure 1) is mainly applied to the thin veined ore body above the 50m level above the 10th line of the southern margin For mining, the thickness of the ore body is generally 2 to 4 m, and the extension height is generally about 6 m. In the ore body, along the ore body, the mining and mining roadway is combined with the mining roadway. The roadway section is 2m×2m. At the same time, the prospecting roadway is arranged on both sides of the roadway to find out the ore body boundary. Finally, the backward brushing and topping are used for mining and mining. The width is generally around 4.0m. If the ore body is thicker, the vertical ore body will be arranged with a number of mining roadways spaced about 3m apart. When the backward mining mode is adopted, the adjacent mining roadway will leave 2m×2m point columns, and the rock with poor stability can leave the column; The extension height is greater than 6m, and the middle section of the top and bottom pillars can be reserved for about 5m. The middle section is first taken back, and the top and bottom columns are recovered. The middle section and the section are respectively arranged to connect the pedestrian wells, the mine shafts and the slopes to ensure two safety exits. The slag machine is used for mining with 0.7m3 mine car or trackless equipment. It is estimated that the mining method will recover more than 23,100 tons of sporadic small ore bodies, the mining loss rate and the depletion rate are all about 5%, and the comprehensive copper grade is 0.78%.
2.2 Pillarless shallow hole retention ore filling method The mining method (see Fig. 2) is mainly applied to sporadic small ore bodies with buried depth exceeding the segment height. When the ore body thickness is ≤6m, the ore blocks are arranged along the strike. The length of the ore block is the length of the ore body. Generally, 50m is a ore block, and the width is the horizontal width of the vein. The stage height is 12m. There is no top and bottom column. When the ore body thickness is >6m, the ore block is vertically oriented and the ore block is divided. For the mine and the pillar, the width of the mine is 4~6m, the length of the vein is the horizontal width, the height of the stage is 12m, the width of the column is 2~4m, the column of the rock can be kept 2m×2m, and there is no top column.

Tu 1
Tu 2

(1) Precision cutting. The mining and cutting engineering mainly includes along the pulse roadway, the mining standard patio, the stopway contact road and the mining contact road. The stage transportation roadway is generally arranged outside the lower part of the ore body, and the distance from the ore body is 4~6m. In order to save the amount of cutting and cutting work, the existing exploration roadway is used as the mining and roadway as much as possible to carry out the exploration and mining combined project to supplement the cutting and cutting roadway. Two mining patios are arranged for the pedestrians. The specification is 1.5m×1.5m. The inclination angle is generally the same as the inclination angle of the ore body. The pedestrian crossing roadway with a section of 2m×2m is cut every 5m. Stope. The cutting work mainly includes excavating the bottoming roadway to form the bottoming space, and at the same time forming the ore-boring channel to open up the free surface for the mining work. Firstly, the mining ore approach is carried out every 6m vertical ore body from the transport roadway. After reaching the ore body, in the lower disk near the ore body, the 2m×2m cutting bottoming roadway is drilled along the ore body, and then up. The disk is expanded to the boundary of the ore body to form a bottomed space with a height of 2 m, which creates basic conditions for mining.
(2) Mining work. Including rock drilling, blasting, ventilation, partial ore mining, dome and flat field, and finally mining. The mining work is carried out from the bottom up and the stratification height is 2m. The operator drilled rock in the ore pile in the funnel well. The depth of the upward blasthole is generally 1.3-1.5m, and the spacing of the blasthole is 0.8~1m. The arrangement of the blastholes is determined according to the thickness of the veins and the difficulty of separation of the ore, and the parameters of the rock blasting are controlled. Strictly control the blastholes around the stope to prevent damage to the surrounding rock and pillars of the upper and lower plates. Carefully control the mining rate to reduce the loss and depletion of falling mines.
The local ore discharge after each blast is about one-third of the blasting amount. The workers use the slag slag machine to mine at the eyebrow line, and the ore remains in the mine to keep the working face at 2~2.5m.
(3) Filling. The upper section of the prospecting tunnel is used as the filling roadway, and the filling tunnel is appropriately arranged according to the shape of the goaf, and the pre-stacked mining waste rock is poured into the goaf for dry filling, so that the waste rock does not go out of the pit, saving Waste rock lifting and transportation costs.
(4) Technical and economic indicators. It is estimated that the mining method will recover more than 34,600 tons of sporadic small ore bodies, the mining loss rate is about 10%, the depletion rate is about 8%, and the comprehensive copper grade is 0.75%.
2.3 Shallow hole retention and medium-deep hole combined mining method This mining method is mainly applied to the end of the sporadic small ore body mining. Because the end sporadic small ore body is relatively isolated, there is generally no corresponding mining project for the upper and lower sections. After the plane features of the ore body are proved, the medium-deep hole disc rig can be used for upward exploration in the middle of the ore body, if the ore body is upward If the extension height exceeds or approaches the section height, the mining project should be properly arranged in the upper section. The mining project should take into account the prospecting and filling needs. In addition, a horizontal drill is placed near the lower part of the ore body for prospecting. If the ore body extends downwards or approaches the section height, the mining project should be properly arranged in the lower section.
The South Rim-200m Section-10 line ore body is a sporadic small ore body exposed in the exploration and mining combined project. The lower dip angle of the ore body is slow. The early exploration mine reveals that the ore body extends upward only 4~5m, and the pressure is expanded. During the mining process, the ore body was exposed in the east-west direction, so the expansion of the mining was suspended. The ore body was inclined to form a ramp along the ore body. The upper ore body gradually became thicker, and the prospecting roadway was arranged at the level of -195.5 m. The drilling rig is vertically arranged to explore the upper hole, and the ore body also extends in height. The ore body is exposed to 320° or so, the ore body tends to the northwest, the lower part of the ore body is inclined at 40°, the upper dip angle is 70°, and the ore body thickness is about 18 m. The extension height of the ore body is about 6~12m. The shape of the ore body is spindle-shaped in the shape of a granitic diorite porphyry not far from the contact zone. The ore body is a skarn type ore body with medium stability and a copper-containing grade of about 1.569%.
(1) Determination of mining methods. Due to the gentle dip angle of the lower ore body of the south edge-200m section-10 line ore body, the lower part of the ore body is connected to the -195.5m horizontal stope in the course of the prospecting process along the ore body. The above-mentioned ore body continues to use shallow hole retention ore mining, and it is necessary to add a pedestrian ventilation ventilated patio, a mining joint road and other mining projects, and the mining cycle becomes longer, and the safety hazard is large. The ore in some mined areas cannot be mined during the mining process. Fully recovered, so the ore block is extracted by the combination of medium-deep hole and shallow-eye diffuse mining. That is, the upper ore body is arranged in the -195.5m horizontal stope to arrange the fan-shaped medium-deep hole and the beam-shaped medium-deep hole for recovery. After the upper ore body is finished, the remaining ore body and the pillar of the lower prospecting roadway are adopted by Atlas 281. Dig into the trolley to expand mining.
(2) Precision cutting. The mining and cutting engineering mainly includes along the pulse roadway, the mining standard patio, the stopway contact road, and the mining contact road. Along the vein roadway has been formed, the south edge -200m section-10 line ore block has been arranged two roads along the direction of the ore body exploration and mining, the specification is 3.8m × 3.1m. -200m section and -195.5m horizontal connection ramp length 28m. In the middle section of the sub-section, the cutting project and the sloping mine are arranged, and the fan-shaped medium-deep hole and the beam-shaped medium-deep hole are arranged in the -195.5m horizontal stope and the slope.
(3) Mining work. The mining work includes medium and deep holes, blasting, ventilation, partial ore deposit, dome and flat field, and final mining. The medium-deep hole blasting began in the middle section of the -195.5m level. After the first 9 rows of deep hole blasting, the scraper enters the sub-segment from the ramp to the mine through the mine. After the blasting in the last 8 rows of deep holes, the shovel The aircraft enters the slope crossing to supply the mine. The boring hole can be arranged in advance in the middle section of the -200m section. After the secondary section is finished, the lower ore body is drilled and recovered by the Atlas 281 boring trolley.
(4) Gob area treatment. Because the South Edge-200m Section-10 line ore body is an independent blind ore body, the mining area of ​​the goaf is closed and isolated.
(5) Main technical and economic indicators. It is estimated that the ore is safely recovering 14,500 tons of ore throughout the year, the mining loss rate is about 5%, the depletion rate is about 8%, and the comprehensive copper grade is 1.52%.
3 Benefit Analysis Since the mining practice of sporadic small ore bodies in Fengshan Copper Mine, the tunneling shallow hole expansion mining method and the bottomless shallow hole retention ore filling mining method have been adopted for different ore body occurrence conditions and relative positional relationships. Various mining methods such as shallow hole retention and medium-deep hole combined mining method, medium-deep hole section and post-filling mining method are used for mining. In 2014, practical application showed that a total of 107,700 tons of sporadic small ore bodies were recovered throughout the year. The integrated copper grade is 0.998%. The comprehensive loss rate and the depletion rate of mining are both 7.6%. The comprehensive mining loss rate is 9.9% lower than the original mining method plan approval index, and the depletion rate is 6.9% lower than the planned verification index. Economic and social benefits. The technical and economic indicators of the ore block are shown in Table 1.

Biao 1


references:
[1] Gu Zhongyuan. Application of Sublevel Method Sandaogou iron ore in [J]. Non-ferrous metals (mine part), 2012, 64 (3): 26-29.
[2] Liu Wei, Zhang Mingwu, Wang Peng. Research and application of the bottomless field method [J]. Mining Engineering, 2009, 7(1): 20-22.
[3] Cheng Station Ming. Tongshan Mining Company residual mine recycling practice [J]. Nonferrous Mining and Metallurgy, 2009 (10): 56-57.
[4] Zhou Yuxi, Zhu Che. The mining method of small ore bodies in the shallow part of the former copper-iron ore [J]. Mining Express, 2008 (4): 79-80.
[5] Lu Zengxiang. Inclined well exploration plan for sporadic ore bodies [J]. Nonferrous mines, 1997(1): 14-16.
Article source: Mining Technology; 2017.17(3)
Author: Mao Yong, Yang Kun; Daye Nonferrous Metals Co., Ltd. Fengshan Copper Mine, Hubei Huangshi City 435 232
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