Recycling of the hanging ore body in Baiyun Obodong Mine

Bayan Obo iron ore and iron ore is the main raw material base of rare earth mine in Baotou, is one of China's major open-air iron mine. The mine began construction in 1957 and has been mined nearly 60 years. It has accumulated more than 300 million tons of ore, which has made tremendous contributions to the country's industrial development. At present, the ore size of the Baiyun Obo iron ore mine is 5 million t/a, and the development mode is automobile-crush-tape joint transportation. With the advancement of mining, the mining area of ​​the East Mine has entered deep mining, and the amount of mining in the open-air boundary is not much. According to the demonstration, the production capacity of the mining site is 3 million t/a, and the service life of the eastern mine is 7 years. 4a. In order to extend the service life of the mine, after exploration, there are hanging mines in the lower opening of the east mine from 1594 to 1230m, most of which are located at 1404~1230m, and the calculated amount of hanging ore is about 25.58 million tons. To this end, the use of Dongfang's existing open-air development of transportation systems and production equipment, before the completion of the open-pit to underground mining preparation work, the recovery of this part of the hanging resources.
1 geological overview
1.1 Geological characteristics
The east section is a complete east-west sloping structure with dolomites on both sides and potassium-rich slate on the shaft. The ore body is strictly controlled by structure. The north wing constitutes the east ore body, the south wing is the Dongjie Legre ore body, the east ore body has a long axis running at N70°E, the western part of the ore body is N60°E in the west, and the east is near. In the east-west direction, the eastern part of the ore body is N75°E in the south and N65°E in the north. It is bifurcated in the northeast corner of the ore body and partially goes to N65°W. The inclination of the ore body is generally steeper on the upper plate, the lower plate is slower, the inclination angle is 50° to 60°, and the local part has a slower or steeper change.
1.2 mineral rock physical and mechanical properties
According to the test report on the physico-mechanical properties of surrounding rock in the study on the stability of deep mining slope in the east of Baotou Steel's Baibo Ebo Iron Mine, the physical and mechanical properties of the main rock (mineral) rock in the East Mine are shown in Table 1.

Biao 1

2 hanging ore body recycling production capacity verification
According to the calculation formula recommended by the mining manual, verify the production capacity of each segment according to the descending speed.

Shi 1

In the formula, A is the segment production capacity, 10,000 t/a; V is the descending speed of the mining face, taking 26 m/a; S is the mining area of ​​the mining section, according to the segmentation quantity, 10,000 m2; r is the ore The bulk density is 3.34t/m3; ρ is the ore loss rate, which is 25%; β is the waste rock mixing rate, which is 20%; E is the geological influence coefficient, which is 0.9. The hoisting ore body adopts intensive mining, and the two sections are simultaneously harvested, and one stage of production is arranged. The infrastructure construction and production mining have a certain amount of advance, and the part of the ore is extracted by underground mining method. After calculation, 200 can be formed. The production capacity of 10,000 t/a ore.
3 development system
3.1 Development plan selection
According to the report of the research on the mining scheme of the deep ore body of the mining section of the Baiyun Obo Iron Mine in the Mining Research Institute of Baotou Iron and Steel Group, the hanging ore body adopts the development plan of Pingshuo.
3.1.1 development
According to the relative position of the Pingyi and the ore body, it can be divided into: the upper plate penetrates the pulse and flats; the lower plate passes through the pulse and develops; The following is a brief description of the main components of Pingyi's development by taking the pulse flat development method (Fig. 1) as an example. When the inclination direction of the vein and the slope is opposite, the tunnel is drilled through the lower vein to develop the deposit. Pingyi Pioneering and Mining System: The ore collected in the middle section of Pingyi is generally transferred by the mine car, and is discharged to the level of the flat by the mine, and then transported out of the surface by the mine. Pingyu develops a rock system: the upper middle section of the rock can be discharged to the ground by a special rock-sliding well to the main transport flat, or when the upper part of the flat has a surface exit, it is discharged directly from the middle to the surface.

Tu 1

3.1.2 East mine hanging up ore body development
The hanging ore body is staged for mining, the level of 1230m is the stage transportation level, and the amount of hanging ore at the level of 1404m is less, and mining is not allowed.

2 ore slides, 1 return air patio, 1 intake patio and 1 waste rock slide.

(1) Hirats. Pingyi is located at the level of 1230m and is located at the bottom of the open boundary of the East Mine. The car is transported in Pingyi, and the mine car is transported out of the Pingyu road after loading the mine at the lower mine. The ore is transported to the ore dumping platform of the east mine stop. The rock is transported to the 1502m horizontal rock tape. Station, broken and transported to the III# dump by rock tape.
When the production scale of the hanging ore body is 2 million t/a, the transportation requirements can be met by using three existing open-air vehicles.
(2) Slope road. The slope of the ramp is located at the 1404m elevation turn of the open pit, and the slope is designed according to 15%. The foundation of the hanging ore body is drilled to the level of 1305m, which is used as the passage and infrastructure of the trackless equipment entering the stope. The level of mining is declining, and it is deepened step by step, and together with the ventilation patio of the stope, it is used as a fresh air passage for the hanging body.
(3) Return to the wind well. The setting of the return air well takes into account the continued use of the deep ore body during mining and the location closest to the hanging ore body. At the same time, for the sake of construction safety, consider using the wind well construction 1230m flat.
The 1230m transport flat is a single-lane driveway, and the car is directly loaded at the mine's lower mine mouth, and a signal source is set at the port.
The ventilation system of the hanging ore body is single-wing diagonal ventilation, the intake wind inlet patio, the slope road, the 1230m flat wind inlet, the wind well return air and the stopway patio return air. The main fan is used for ventilation, and the main fan is arranged at the wind turbine station of the industrial ground surface of the wind well.
The wind inlet patio of the stope is arranged outside the wrong boundary of the mining and mining body. There is a ladder room inside, the upper elevation is 1650m, the lower elevation is 1230m, and it is used as the second safe exit of the stop. The return air return patio is arranged at the end of the ore body.
The underground gushing water from the mining and mining body flows through the flat shovel to the open pit sump, and then is pumped to the surface pumping station by the original open pit drainage system for surface water transportation to sprinkle water and dust.
The hanging ore body is mined by the bottomless sublevel caving method. The section height is 15m, and the top two sections (60, 75m sections) are combined into one section, which is used as a topping section to form an ore cover layer. The ore body above 1404m level has less ore and does not mine.
3.2 Rock dislocation boundary delineation
The displacement angle of the rock for mining the ore body is shown in Table 2. Based on this, the rock fault boundary is delineated and the layout of related development projects is considered.

Biao 2

3.3 Hanging the end of the ore body
Outside the end of the hanging ore body is an open pit, the pillar must be retained to prevent the falling ore from falling into the open pit, and at the same time create conditions for the mining and blasting to improve the blasting effect. Considering that the slope of the part will landslide after the mining of the ore body, there will be a cover layer at the end of the ore body at the bottom section. Therefore, the bottom section can leave no end pillar.
In this scheme, the pillars of the 1404~1260m section are reserved, and the 1245m section does not leave the end pillars. In actual production, it is possible to determine whether the bottom sections need to retain the pillars according to the condition of the end section of the mining section.
3.4 transport flat layout
The ore transport of ore bodies can be considered to utilize the existing open-air transport vehicles of the mine. The transport flat is arranged in the outer rock of the 1230m horizontal ore body, and is used as the sectional lower plate contact when the 1230m horizontal ore body is mined.
Considering that during the mining process of the hanging ore body, the west end slope of the open pit will produce landslides. For safety reasons, the transport flat sluice is arranged outside the maximum landslide coverage of the north side slope of the open pit.
3.5 mine rock slide layout
In the mining of the hanging ore body, two sections are used for simultaneous mining. For the safety of unloading, two ore shafts and one waste rock shaft are arranged, and one ore shaft service is provided for one section, so as to avoid two sections simultaneously to one section. The ore is discharged from the mine.
3.6 slope layout
The slope of the hanging ore body is only responsible for the mining service of the hanging ore body, and the service is above the level of 1245m. According to the function of the ramp, the ramp is divided into three sections: 1 section, 1404~1350m, which undertakes the task of lowering the intake equipment of the stope, as well as the infrastructure development and the slag discharge channel; 2nd section, 1350~1290m, undertake equipment Downhole mission; 3rd section, 1290~1230m, to meet the deep ore mining equipment from 1230m flat to 1260,1245m section to strengthen mining and mining ore body.
4 choice of mining methods
Because the hanging ore body is assigned to the lower part of the northern side of the stope, the slope is about 350m high, and the slope above the elevation of the mining body is as high as 200m. The thickness of the ore body is large, and the sublevel caving method is used as the 1230m. Iron ore mining method below the level, this method is safe and efficient [1-2].
In order to ensure the safety of the mining approach, the mining approach is perpendicular to the open end slope and is retracted from the open end slope. Sectional rock drilling, section mining, ore is discharged to the ore.
Combined with the actual experience of domestic mine production and large-spacing test data, the east mine hanging ore body is suitable for larger structural parameters. The recommended mining structure parameters are 15m×15m (segment height×way spacing).
When the thickness of the ore body is greater than 15m, the vertical direction of the mining ore body is arranged. When the thickness of the ore body is less than 15m, the mining route is arranged along the ore body. The thick ore body adds a communication channel in the middle of the ore body. The distance between the contact roads is 50m, and there are 1 ore block for every 6 roads. The plane size of the ore block is 90m×50m.
The section parameters of the mining route (width × height) is 4.0m × 4.0m. As long as the stability of the ore body is allowed, the width of the approach can be larger to obtain better mining effect.
5 Conclusion
The mining site of the East Mine has entered deep mining, and the amount of mining in the open-air boundary is not much. After the open-pit mining, the ore body should be mined first, and then the ore body below 1230m level should be mined to ensure the continuous production of the east mine to the underground mining. And underground mining as soon as possible. Suggestions for the mining of the east mine hanging ore body: 1 Prepare the production plan for several production levels of the open pit mine, and comprehensively determine the final end time of the open-air production according to the mining equipment conditions, the stope conditions, and the construction time of the hanging ore body; The mine production time schedules the construction period of the ore body to ensure that the production of the ore body can be connected with the open end of the open pit mine, and the transition from open pit mining to underground mining is realized; Important, the vibration caused by blasting and slope deformation is the main safety hazard. The blasting vibration and slope deformation monitoring system should be arranged according to the actual situation to ensure production safety.
[1] Cai Lujun, Ma Jianjun, Jiang Bing, et al. Research on high-steep slope-hanging mining method [J]. Metal mines, 2016 (1): 65-67.
[2] Zhou Zhigang, Hao Quanming, Yan Yingjie, et al. Application of sublevel caving without pillar in the eastern mine of Bayan Obo Iron Mine [J]. Modern Mining, 2015 (11): 31-33.
Article source: "Modern Mining"; 2016.11
Author: Zhou Zhigang 1, 2, Hong Guomin 2, Mou Yingjie 2, Haoquan Ming 1;
(1. Mining Research Institute of Inner Mongolia University of Science and Technology; 2. Mining Research Institute of Baotou Steel Group);

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