Open-pit mining of Yanjin Mine——Application of horizontal expansion and transverse skew mining in steep mining

The research and application of the steep mining technology has greatly improved the passive situation of high production and stripping ratio in the open pit mine, and played a positive role in effectively reducing the stripping flood peak, balancing the production stripping ratio, reducing the amount of infrastructure stripping and infrastructure investment.

Shandong on warehouse gold mine Laizhou since 1989 began to use in production steep slope mining technology, the cooperation between the mining process on the steep slope, the role of the relationship between mining parameters with equipment efficiency and production technology management made a bold attempt, made Significant economic benefits.

First, the program features

The upper part of the gold deposit in Cangshang has a Quaternary covering of 10~12m thick, and almost all of the above-mentioned -34m is oxidized ore. The average thickness is 10.9m, which is horizontally distributed, followed by mixed ore and primary ore. 48 ° ~ 83 °, the thickness of the ore body is 0.3 ~ 43.3m. In the actual production of the mine, considering the factors such as equipment conditions, scraping efficiency, and mining capacity, the method of longitudinal longitudinal mining and stripping along the longitudinal strip is adopted, which is increasingly unsuitable for production. Under the condition that the basic design of the basic open-pit mining parameters is unchanged, the following schemes are studied from the balance of maintaining the balance of the two polarities, reducing the depletion of mining losses, improving the shipping efficiency, and reducing the initial production stripping ratio; The rear-end mining method; the vertical peeling of the moving pit line on the upper plate is the horizontal stripping of the temporary pit line; the mining is changed from the original longitudinal small step (6m) mining method to the horizontal oblique mining method (12m).

Second, steep gang rear mining

According to the characteristics of the mine, the Shangshang Gold Mine adopts a combined step stripping process, and the stripping equipment runs along the striping strip. The excavators are trailing each other between the adjacent steps in the combined step, and the working platform width is 40~. 45m, the horizontal distance between the electric shovel is 150~200m. When the step is pushed forward, the excavator is transferred to the next step. After the next step is pushed, the excavator is transferred back to the previous step to re-work, and then the operation is repeated up and down. The steps advance to the final level (see Figure 1). The lower plate is stripped using a single step stripping process. The main parameters of the combined step mining and stripping process are: working step height 12m, advancing width 25~30m, temporary non-working platform width 15m, transport platform width 15m, combined step number 4, step slope angle 68°.

Figure 1 Schematic diagram of two rows of shovel tailing operations

Compared with the single-step stripping process, the combined step stripping process can remove 101.15 million m ^{3 of} rock during the infrastructure period. Although it is stripped 100,000 m ³ per year during the production period, only one 20t car can be added. The need for transportation, which effectively reduces the peak of the stripping, and balances the production stripping ratio.

Third, the temporary pit line lateral stripping

Open-pit mines transported by car, because of the short connection between work levels, the long-distance work line is not required for the installation, so there is no need to use long-excavation work lines or long mining areas for open-pit mining, plus large areas. The success of multi-row micro-difference blasting can prepare enough ore for the mining in a short working line, so the mining scheme of various horizontal mining belts came into being. The open pit of Cangshang Gold Mine is relatively small. The upper part of the stope is 350m×390m, and the bottom size is 260m×20m. The thickness of the ore body is not large and the maximum thickness is 43.3m. The previous stripping process is a longitudinal working line. After the remineralization zone, with the increase of mining depth, the size of the stope operation is gradually reduced, facing the transition from a large realm to a small realm, making it more difficult for the mine to develop transportation and new level preparation. After the research, the Shangshang Gold Mine has improved the situation by adopting a new process of horizontally stripping the temporary pit line without segmentation.

The so-called temporary pit line is a temporary passage between two adjacent levels in the deep pit. It is the same as the moving pit line. It communicates between two adjacent levels in a certain interval and space, but the difference is the movement of the pit line. The upper and lower triangular palms need to move continuously on a regular basis, and the temporary pit line is abolished after completing the mission. Then, a bulldozer is used to push a ramp on the explosive pile at the appropriate location to form a temporary pit line between adjacent levels (see figure 2 and Figure 3).

Figure 2 Schematic diagram of vertical expansion of a horizontal moving pit line

Figure 3 Schematic diagram of temporary pit line development

In the open-pit mining process, the trenching speed largely determines the new level of preparation speed and the production capacity of the open pit. The so-called non-segmental trenching refers to the slope, that is, after the tunnel is digging, it is necessary to excavate the trench. Expand and form the stripping face, so that the new level of preparation cycle can be shortened by using trenchless mining.

The new level is ready for the first blast on the working flat plate of the combined step mining, using a central gutter ring to detonate. In the blasting area, the electric shovel directly excavates the ditch into the new level, and the vertical boundary advances into the horizontal mining. In the process of horizontal expansion, due to the blasting and lowering of the combined step mining, when the lower potential is thrown, the reverse transportation is not only increased, but also the amount of tunneling of the pit line is large, which affects the transportation operation and increases the width of the temporary non-working platform. , it is not conducive to improve the work slope, so the normal production blasting uses slash multi-segment sequential differential blasting to control the blasting bypass distance.

The improved stripping and stripping process sequence is slightly advanced in the lateral stripping work of the upper plate, and the horizontal mining of the ore belt is followed by the stripping of the lower plate. The relationship between the stripping sequence and the reserve amount is shown in Fig. 4.

Figure 4 Relationship between mining and stripping sequence and mined quantity

Fourth, horizontal oblique mining method

Due to the complicated variation of local stone formation in the deposit, the control of each horizontal production slot alone has the current situation of insufficient precision and unclear production of stone. Due to the irregular shape of the ore body and the large change of the angle of the lower plate, the use of longitudinal slow mining has undoubtedly increased the loss of ore loss.

On the basis of horizontal mining, the Shangshang Gold Mine adopts the oblique angle mining method, so that the mining work line and the inclined ore body are inclined obliquely 30°～60°, so that the ore of each ore is exposed and the ore grade is divided. In order to achieve the purpose of eliminating stone, rich and poor, mining and neutralization.

The horizontal skew mining method is adopted to sequentially determine the stripping boundary and the mining operation from the upper plate to the lower plate of the stone, which is beneficial to reduce the depletion of the ore loss, because the inclination of the ore body and the tendency of the mining face are "isotropy". The control relationship is that the ore body is on the top, the rock is on the bottom, the ore is depleted, and the ore recovery rate is high.

V. Conclusion

(1) To achieve steep mining, combined with step-type mining with rear-end lateral propulsion, greatly reducing the amount of expansion and stripping, effectively reducing the peak of stripping, balancing the production stripping ratio, and making the final slope exposure time greatly Delayed, increased mine economic benefits.

(2) The longitudinal stripping of the mobile pit line was changed to the horizontal stripping of the temporary pit line. It has been proved that the bipolar mineral quantity has reached the national standard, ensuring stable production of the mine, reducing the transport distance in the pit by 0.15km and improving the efficiency of the shoveling by 25%.

(3) The mining has changed from the original longitudinal small step (6m) mining to the horizontal oblique mining (12m), which has improved the mining capacity of the stope and reduced the mining cost. Any ore that reaches the thickness of the stone can be easily removed. All of them were produced, and the lower boundary of the ore body was effectively controlled. The recovery rate increased from 95% to over 97%, and the depletion rate dropped from 8% to less than 5%.