Study on mining method of steep slope and unstable ore body in Chashan Mine

0 Preface

Southern Star Dasan mine is underground Nandan county mining enterprises, mining object Dachang tin ore field Dasan antimony mine tungsten metal 28 Vein. The No. 28 vein vein is developed and the structure is not stable. Since the establishment of the mine, the mining and mining method has been adopted, and the mine is blasted from the bottom up.

Over the years, the Chashan Mine has suffered from top-level accidents. According to statistics, there were 19 production safety accidents in the Chashan Mine from 2005 to 2010, with 20 deaths, including 14 roofing accidents and 10 incidents in the stope. Frequent accidents have had a very bad impact on the normal production of the Chashan Mine.

Taking Chashan Mine as an example, this paper discusses the mining method and safety technology of Chashan Mine's steep slope, unstable structure and solid ore body, and proposes a safe, efficient and operable mining method.

1 Mine Overview

The Chashan mining area covers an area of ​​2.743km2, and the geographical coordinates are 107°37'50′′ east longitude and 24°50'17′′ north latitude. The mining method is the shallow-eye retention method. The development method is joint development of Pingyi+blind inclined well and inclined well+blind inclined well. The central air inlet and the two-wing return air ventilation are adopted.

The Chashan mining area is located at the southern end of the Danchi metallogenic belt. The No. 28 vein in the mining area is a quartz vein low-temperature hydrothermal filling vein. It belongs to a deposit controlled by fault structure. The ore body is quartz vein, the boundary of the ore is clear, and the ore body is poor in stability. The rock structure is unstable and is prone to natural shedding after being exposed. The average ore angle of the ore is 33.5°, the body weight is 2.93t/m3, the loose weight is 1.83t/m3, the surrounding rock weight is 2.5t/m3, and the looseness coefficient is 1.6.

2 Introduction to the original mining method

2.1 Original mining methods and improvement measures

For the steeply inclined thin veins, the Chashan Mine is mined by the shallow-eye mining method. The main rock drilling equipment is the YSP-45 gas-leg rock drill , which uses funnel mining and manual loading.

(1) Nugget structure. The mine room is arranged along the veins, generally 40 to 60 m long, and the width is the horizontal thickness of the ore body. The width of the column is 3 to 4 m, the thickness of the top column is 3 to 4 m, and the bottom column is not left. The spacing of the ore hopper is 5 to 6 m.

(2) Precision cutting. After drilling and transporting the alleys in the veins near the lower plate, the distance between 40 and 60 m is taken as a stope, and the two ends are dig up into the mountain, and the YSP-45 type upward rock drill is used to make the blast hole. °～85°, the hole depth is about 2m. After the blasting, the ore is shipped, the roadway is cleaned, and then the false bottom wooden bracket is set up, and the wooden funnel is set at the same time.

(3) Mining mining. The mining operation starts from the false bottom and is layered upwards. The YSP-45 type up rock drill is used to hit the blasthole. The blast hole inclination angle is 75°-85°, and the hole depth is about 2m. After the blasting and ventilation, the workers enter the stope to sort the ore, the ore, the turquoise treatment and the flat, and then carry out the next cycle of rock drilling.

(4) Ventilation. During the mining process, the fresh air flow enters the working face of the stope through the pedestrian ventilation ventilated patio, and the dirty wind returns from the other side patio of the stope to the upper middle return wind tunnel.

(5) Mining and mining of the pillars. Under the condition that it does not affect the mining of other ore blocks, the column is recovered by one method, and the top column is not recovered in principle. The middle section of the recovery has been closed, and the empty area is processed by the closed method.

In view of the problem that the roof of the stope is unstable and easy to fall, the mining method was optimized in 2007. The focus was on technical improvement in rock drilling and blasting. The original blast hole from 75° to 85° was changed to horizontal blasthole. The smooth blasting is used to reduce the damage to the roof and improve the stability of the roof. In 2008, the use of the extra-pulse no-pillar shallow-eye retention method and the reinforced concrete pseudo-bottom shallow-eye mining method were carried out, and the mining experiment was carried out, and a certain effect was obtained.

2.2 Original mining methods and improved evaluation

The ore grade produced by the original mining method is relatively high, the mining and cutting engineering volume is small, and the recovery cost is low; however, its safety guarantee level is low, the production capacity is low, the mining capacity of the stope is low, the amount of pit wood is large, and the maintenance of the roadway is difficult. Large, the main transportation line is not smooth.

After adopting the improvement measures, it will play a certain role in the roof collapse. However, due to the unstable structure of the gangue, the effect of preventing the roof accident is not obvious, and the casualties occurring in the stope have not been reduced. The improvement of the mining method has not put forward effective safety technical measures to prevent the roof from falling, and the safety problem of the roof is not solved.

3 new mining methods research

In view of the safety problems of the unstable thin ore body in the steep slope structure of Chashan Mine, two feasible mining schemes are proposed while taking into account the mine production efficiency.

3.1 Scheme 1: The deep hole segmentation method in the bottomless column

(1) Arrangement of stope structure. The stope is arranged along the veins. The height of the stope is 40-45m, the section height is 13~15m, and the length of the stope is 60-80m. The specific length depends on the continuity of the vein and the width is the thickness of the vein. Without leaving the top and bottom columns, only the columns are left, and the columns of the upper and lower stop are staggered in the vertical direction (see Figure 1).

(2) Cutting and cutting engineering layout. Dig along the veins into the vein roadway, staged rock drilling road, pedestrian pavement (2), cutting the patio, and 6~8m along the vein roadway to excavate the main transportation lane outside the vein, and excavate the mine and the roadway every 5~7m. Connected, the pedestrian patio, the cutting patio and the staged rock drilling roadway are all arranged in the vein. The pedestrian patio is also used as a ventilation shaft in the stope, and no ventilation shaft is provided. Taking the span of 60m and the height of the stage of 40m as an example, the amount of cutting work is calculated (see Table 1).

(3) Rock drilling and blasting. The cutting patio is used as the blasting free surface, and the vertical upward and downward blastholes are chiseled in the sectioned rock drilling roadway and along the vein roadway. The rock is drilled in the sectioned rock drilling road, and the upper blasthole is first chiseled, and the lower blasthole is drilled. The lower part is firstly blasted, and the upper part is blasted simultaneously with the lower part of the previous tier, and blasted in stages from bottom to top, and the mine is dropped by self-weight.

The ore that has collapsed is mined from the ore roadway by the mining machine, and the amount of ore is more than 3m in the stope. After the mine is harvested, the mine roadway will be blocked in time to ensure the safety of the main transportation lane.

(4) Ventilation and safety management of the stope. Fresh air flows from the pedestrian patio into each staged rock drilling, and the dirty wind is discharged from the other return air patio to the upper middle return airway. Under the condition of ventilation to ensure the air quality of the stope, the personnel enter the in-pulse roadway and the staged rock drilling road, firstly treat the roof and the side to help the loose rock, and the unstable section needs to be supported by the anchor net to ensure that it is carried out under the premise of safety. A cycle of work.

3.2 Option 2: Top-down shallow-layer stratified empty field method

(1) Arrangement of stope structure. The stope is arranged along the veins, and the height of the stope is 40-50m. The length of the stope is 60-80 m. The specific length depends on the continuity of the vein and the width is the thickness of the vein (see Figure 2). Leave the bottom column, do not leave the top column and the column, and support the anchor column (see Figure 3).

(2) Cutting and cutting engineering layout. The veins along the veins and the mines are drilled along the veins. The distance between the mines is 15~25m. There is no obvious change in the veins between the two mines. The excavation roadway is excavated at the bottom of the ore-boring shaft at a distance of 5 to 7 m from the inner roadway. Taking the span of 60m and the height of the stage of 40m as an example, the amount of cutting work is calculated (see Table 2).

(3) Rock drilling and blasting. The blasting free surface is used as the blasting free surface. Starting from the bottom plate of the middle section of the upper middle section, the blasthole with a dip angle of 50°~70° is cut downward, and each row of 3~5 rows of blastholes is stratified every 2m. The blasting method adopts a non-conducting squib and a detonating cord double-type detonation network to perform multi-row differential detonation. Simultaneous rock drilling, blasting and mining at different working surfaces at the same level. The electric ore is used for ore mining, and the ore slag machine is used to load the ore in the mining roadway (see Figure 4).

(4) Ventilation and safety management of the stope. Fresh airflow enters the mining face from the adjacent goaf, and the dirty wind is discharged from the upper middle roadway to the return airway. After the end of each layer of mining, carefully clean the side to help the loose stone, the unstable section for anchor net support. As the mining operation moves downwards, a pedestrian ladder is built from above. The pedestrian ladder should be fixed on the surrounding rock and installed with handrails.

3.3 Program Technology Economic Comparison

The comparison of the main technical and economic indicators expected in Option 1 and Option 2 is shown in Table 3. Both of the solutions solve the safety problems of the operation. Among them, the first one needs to carry out the middle section rock drilling road excavation, the construction is difficult, the process is complicated, the mining and cutting engineering volume is large, and the medium and deep hole rock drilling machine is needed at the same time; the second plan needs to pick the bottom after completing a layered mining. Reduce the position of the electric winch and reinstall the antimony winch. After the blast, the ore is transported to the mine. However, in the whole process of the second recovery, the upper ore rock is supported by the anchor net, which can effectively prevent the danger of the instability of the vein. In addition, in addition to the relatively difficult construction of the slipping patio, the rest of the construction process is simple, and the rock drilling, blasting and mining ore transportation operations are not demanding on the construction equipment and the operation is easy.

By comprehensively comparing the technical and economic indicators of the two schemes, as well as the advantages and disadvantages of their respective processes, the scheme of top-down shallow-layer stratified empty field method is selected as the mining method for the steep tilting and structurally unstable thin ore body of Chashan Mine.

4 Conclusion

The recommended top-down stratified empty-field mining method changes the traditional bottom-up mining method, using the upper middle column as the support, and anchoring the net to avoid personnel under the changing exposure surface. The operation and recovery process are safe and secure. At the same time, the mining method has simple recovery process, high production capacity, meets the production capacity requirements of the mine design, and has good applicability to the steep tilting unstable thin ore body of Chashan Mine.

references:

[1] Zhu Jianguo. Design of the mining plan of Chashan Mine of Nanxing County, Guangxi Province [R]. Nandan: Chashan Mine of Nanxing Yiye Co., Ltd., 2007.

[2] Changsha Nonferrous Metallurgy Design and Research Institute. Optimization design of mining method of Chashan Mine of Nanxing County, Guangxi Nantan County [R]. Nandan: Chashan Mine of Nanxing Yiye Co., Ltd., 2007.

[3] Luo Huaichang. Exploring the mining method of steep inclined thin ore body in Chashanyu Mine[J]. Mining Technology, 2009, 9(4).

[4] Wang Jiang. Research on mining method and safety technology of steeply inclined thin ore body [D]. Changsha: Central South University, 2015.

[5] Lin Cong. China Metallurgical Encyclopedia (Mining) [M]. Beijing: Metallurgical Industry Press, 1992.

Author: Hude Xiang; Nandan town car enterprise management office, Nandan 547,204;
Source: Mining Technology 2015, 15(5);
Copyright:

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