Optimization of low-depletion mining sequence for inclined thick ore bodies

0 Preface

The gently inclined to inclined thick ore body belongs to the type of difficult mining body, especially when the inclination angle of the ore body is 35°～40°, one of which is because the inclination angle of the ore body is not steep enough to realize gravity drawing in the stope, resulting in mining. The process is complicated; the second is that the order of reasonable ore body mining is difficult to determine, and it is very difficult to achieve efficient economic mining. By changing the way of ore-breaking ore, the ore can be effectively transported, and the thick ore bodies are mostly divided into two-step or multi-step recovery. The reasonable recovery sequence will directly affect whether the ore body can be efficiently and safely recovered. Therefore, the development of a suitable recovery sequence suitable for the occurrence of such deposits is the key to achieving efficient and safe mining.
1 Introduction to mining technical conditions and mining methods
1.1 Mining technical conditions
A rock gold deposit is controlled by the fault structure and the altered joint fissure zone. Mainly composed of the 1st and 70th pulse groups. The No. 70 vein group consists of 7 veins, mostly thick ore bodies that are gently inclined to slope.

It is distributed in the upper plate of the No. 1 vein group south of the 7th line. The veins are all present in the silicon-potassic monzonitic alteration zone. The overall distribution direction of the alteration zone is 0°-350°, westward or southward, and the inclination is 20°. ~45°, the alteration bandwidth is 130-300m. The ore body is continuous and complete with good stability; the surrounding rock of the top and bottom plates has good stability and strong weathering resistance, and is a hard-semi-hard ore body. The engineering geological exploration type is simple and the hydrogeological conditions are medium. The middle section of the main mining is the middle section of 1304~1184m.
1.2 Mining methods and mining status
According to the current situation of ore body mining above the middle section of No. 70 vein 1264m, the ore body above 1304m adopts shallow hole empty field method and medium-deep hole open field method to recover, leaving part of supporting pillar and middle section bottom structure in adjacent stope, passing through empty area. In the survey, most of the supporting pillars in the middle section of 1304m collapsed, the roof of the stope fell seriously, and the empty zone was connected in one body, and the supporting pillar could not be recovered. The 1264m middle ore body adopts two-step mining, and the first step is 10m wide. The stratified medium-deep hole or shallow hole is used to form the goaf. The empty top time is several years to ten years. The second step is wide. 20m, no mining, in order to meet the requirements of 2500t / d production capacity after the technical transformation and the continued development of the mine, it is urgent to pick up this part of the ore body.
The original design one-step mining site is filled with block stone cement, and the surface stone is transported to the underground to fill the stope. However, due to the fact that the adjacent ski resort area cannot damage the surface vegetation and environment, the block cement filling is not implemented. The purchase of waste rock or river stone for filling is not possible due to high cost and large filling capacity. The ore dressing process at the time of the mine was carbon cyanide. The tailings of the ore dressing were more toxic. If the tailings were filled into the underground to contaminate the groundwater resources, they could not be filled into the well as filling materials. Filling mining methods should not be used because there is no suitable filling material. Therefore, considering the use of empty field recovery and rear caving treatment, the reasonable layout of the panel, stope and middle section will directly affect the rational and effective mining.
2 panel stope and middle section mining sequence
2.1 panel mining order
For the three existing 20m wide pillars in the middle section of 1264m and four one-step emptyfields, two mining columns are used to pick up the mining sequence.
(1) Continuous recovery of continuous mining in the stope of the panel. The scheme adopts the 23N22, 21N2, and 19S18 stop fields from south to north, and after the 23N22 stope is recovered, the roof of the 3231 stoppage is forcedly topped, and the roof surrounding rock fills the empty area. The stope mining is ahead of a top-mounted stope, so that the collapsed waste rock will not fall on the ore pile in the mining stope, which can reduce the ore loss and depletion rate. In the middle section of the scheme, there is only one stope at the same time, and its recovery is shown in Figure 1.

(2) The interval mining area is separated by one interval and one interval. The scheme firstly picks up two mining sites 23N22 and 19S18 at the same time. 21N2 is used as the mining area of ​​the mining area after mining. After the majority of ore is recovered from the empty field, the 21N2 pillars are forced to collapse in the north and south wings of the mining area, and then the 21N2 is recovered. In the pillar mining stope, the 21N2 stope is blasting and mining under the surrounding rock of the collapsed roof. The scheme can realize the simultaneous recovery of two stope in the middle section and increase the production capacity of the panel. The recovery is shown in Figure 2.

2.2 Stope mining sequence
In the panel, the two-step segmental empty field and the subsequent caving mining method are adopted. The middle section is divided into two sections. Since the ore body belongs to the gently inclined to inclined ore body, the cutting well must be arranged at the end of the stope. A reasonable distance from the end of the stope, the upper part of the cutting well is located on the upper plate of the ore body, and the ore is depleted during the recovery. A part of the ore body in the lower part of the cutting well is outside the cutting well, and normal recovery is difficult to recover, so at the stop end Fan-shaped deep holes are arranged in the rock-drilling roads, and this part of the ore is recovered as much as possible to reduce resource losses.
The mining sequence in the stope: firstly pull a section to cut the vertical trough, the cutting well is arranged in the center of the stope, the cutting well is the free surface, and three parallel deep holes are arranged in the cutting cross, the row spacing is 1.2m, The cutting well is a free-face blasting to form a segmented cutting vertical groove, and the cutting vertical groove is used as a free surface to recover the segmented triangular ore body. After the ore is pulled out, the cutting vertical groove is used as a free surface, and the medium-deep hole blasting is one point. In the segment, when a segment is recovered and aligned with the blasting vertical groove of the second segment, the two-section ore body is recovered to form a step-type mining, and the second segment is advanced by 2 to 3 m until the complete mining site is recovered. . See Figure 3 to Figure 5 for the stop cutting of the stope, the mining of the sectioned triangle ore body, and the mining sequence of the stope.

2.3 middle section mining order
The upper part of the upper part of the mining area adopts the empty field method to recover, and after one step of the mining field, the second step is left uncollected. In order to meet the production capacity requirements of the mining area, the multi-middle working face operation is required, the order of recovery is strict, and there are major safety hazards, and the production capacity is constrained. In addition, the bottom column and the top column of the middle section cannot be harvested as soon as possible, and local ventilation is difficult. The ventilation cost is high and the maintenance cost of the roadway is relatively high. Therefore, a reasonable middle-stage recovery order and excessive connection mode are especially important.
At present, the mining area development project has reached the middle of 1184m, and the preparation of mining volume is formed. In the middle of 1224m, it is proposed to adopt the two-step empty field and the tailings cement filling filling method. After the mine adopts the filling mining method, after the whole middle section development system is formed, the middle section can realize the bottom-up mining. After the middle section mining end, the middle section of the middle section is recovered, and then the whole middle section is closed to reduce the operating cost of the middle section ventilation. Maintenance costs. The lower middle section of the goaf can be filled with waste rock and tailings waste in the upper middle section, so that the waste rock can not be pitted, thereby reducing the transportation cost of waste rock, and the ground can also reduce the waste rock yard, protect the land resources, and reduce waste. Environmental impact and pollution.
3 summary
(1) For the quarry of the middle section of a large-scale rock gold mine, two schemes of continuous mining and continuous caving of the stope and separation and separation are proposed. Each has its own advantages and disadvantages, which can be based on actual production and distribution, and safe production. Demand, after the program is optimized, a reasonable order of the panel recovery is determined.
(2) Combining the upper empty field method of the mining area with the lower filling method and the complicated mining environment of simultaneous mining in multiple middle sections, a reasonable middle section mining and mining sequence is proposed, and the rational arrangement and the mining section cutting vertical trough and the upper triangular ore body are It can maximize the recovery of underground mineral resources, lay a foundation for meeting the requirements of mine production capacity and the connection of reconstruction and expansion projects, and can provide reference and reference for mining with similar conditions.
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