Jinshan store iron ore was built in 1958, the annual design scale mining of 300 million t, iron ore concentrate annual production capacity of 1.4 million t. The Jinshandian iron ore mine has been exploited by sublevel caving without pillars. The surface collapses in many places [1]. The time and extent of surface subsidence far exceeds the prediction, which seriously affects the continuous production in the eastern part of the workshop; Increase, the range of surface rock movement is gradually increasing, and the amount of security pillars is getting larger and larger. If it is not timely recovered, it will cause permanent losses. In addition, Jinshandian tailings storage capacity is relatively tight, and will soon face closure, current land acquisition and The relocation work is more difficult. The Jinshandian iron ore mine is applied by filling method, and the high-concentration full tailings cementing filling process [2-3] can effectively solve the above problems.
1 mining technical conditions
The ore body is produced near the boundary line between the T2-3pq and T2+T1dy7 strata in the south plate of the F3 fault near the contact zone on the southern margin of the rock mass. It is affected by the development degree of the carbonate stratum, the contact structure between the rock mass and the T2+T1dy7 stratum, and the interlayer sliding fracture zone. And F3, F4 fault and other factors control. The surrounding rocks of the upper plate are mainly skarn, argillaceous biotite horn, metamorphic siltstone , and Yingchang hornite, followed by diorite porphyrite, magnetite ore and quartz diorite and marble ; The surrounding rocks are mainly quartz diorite, skarn and marble, followed by monzonitic granite , diorite porphyrite and argillaceous biotite horn rock. The boundary between the ore body and the surrounding rock is clear, the upper plate interface is relatively straight and the interface at the lower plate is soothing and wavy, and the local transition type. The ore body tends to be 203° to 172° to 202° from west to east, and the inclination angle is 85° to 61° from west to east, and 85° to 50° from top to bottom.
The block and disseminated magnetite ore structure is dense and hard, and the joint fissures are not developed. It is a moderately stable ore; the breccia magnetite ore and the skarn-magnetite ore structure are not very tight, and the joint fissures develop. Ore with poor stability; powdered magnetite ore is loose in structure and extremely low in strength, and is a very stable ore. In this experiment, the nuggets are mainly disseminated magnetite, and the content of powdered ore is small.
The main top and bottom of ore stone slate, diorite, marble dense and hard, JOINTED less developed, is a good stability of the rock; I becomes sandstone, hornstone dense structure, but the joint development, is a medium stability Rock; skarn lithology is uneven in hardness and hardness, joint cracks develop, and it is a rock with poor stability.
The structural contact zone (contact zone between the intrusion and the surrounding rock) in the area is broken, the lithology is soft, the groundwater activity is strong, and the rock stability is significantly reduced, which is the weak zone of the deposit. Another weak zone in the deposit is a powdery ore that is lenticularly and irregularly sandwiched between the massive ore to form a weak interlayer.
In this test, the ore block is selected between 25# and 28#, the ore body has a length of 254m, an average thickness of 16.5m, and a mining depth of -368 to -396m. The average geological grade of the ore ore in the test ore is 43.55%, and the geological resource reserves are 990,000 tons.
2 mining method test research
The experimental study of the nuggets is mainly disseminated magnetite, which is a moderately stable ore. It is a full-tailed sand filling mining method after the mined stage in the staged rock drilling stage [4]. The mining method is shown in Figure 1.
2.1 Nugget layout
The ore body adopts vertical ore body orientation, the length of the stope is the thickness of the ore body, the height of the ore block is 70m in the middle section, the section height is 14m, the width of the ore block is 48-60m, the spacing of the access road is 12m, and the ore block is divided into two steps. Mining, first mining room, mining column, mining room, pillar spacing.
2.2 mining cutting
The use of extra-pulse mining, the sub-distribution of the roadway and the mine and waste rock in the lower part of the ore body. The cutting project includes segmented roadway, mining slope road, segmented pulse transportation lane, section rock drilling roadway, mining road, mine waste rock shaft, cutting patio and so on. From the slope of the mining area to the level of each ore level, the ore level is excavated along the vein, and the mining road is excavated from the mining area and the mining column along the vein, and the cutting patio is drilled at the end and the returning roadway of the upper middle section is connected.
The mine roadway is excavated in the adjacent approach, and obliquely intersected with the mining road 45°, and the cutting patio is arranged on the upper part of the ore body.
2.3 mining and mining
The medium-deep hole drilling rig is used to cut the fan-shaped medium-deep hole in the section rock drilling roadway, the row spacing is 1.5-2.0m, the hole bottom distance is 2.0m, and the drilling diameter is 76mm. Detonation is carried out using a 2# rock explosive and a non-electric detonator detonating system. The upper section leads the 1~2 row of shots than the lower section, and forms a step working surface after blasting. The first step is to return to the mining room and the second step back to the mining column.
The WJD-1.5 scraper is used to transport the blasted ore to the ore chute and down to the middle section of the main transportation. The scraper shovel distance is less than 100m.
2.4 top board management
In order to ensure the overall stability of the top column and ensure the safe operation of the lower stope, the support method of the pre-control top is adopted, that is, in the mining access road, the anchor cable is used to strengthen the support on the basis of the original support conditions.
The long anchor cable body is made of 16mm diameter steel stranded wire with a length of 8m. The cable hole with a diameter of 65mm is drilled with YGZ-90 drilling machine , and the cable net is 2.0m×2.0m.
2.5 stope filling
Filling aggregate selected tailings after Jinshandian ore beneficiation [5], ordinary portland cement 32.5 cement grade, high concentrations of added cement tailings by mechanical stirring to a concentration of 64% -68% The high concentration of structural fluid is filled with the slurry.
The filling system is mainly composed of tailings feed line, return line, cement storage supply line, concentrated water supply line, filling slurry preparation and transportation, automatic control system and so on.
The results of on-site sampling and testing of backfill strength are shown in Table 1.
In the first step, the mining room is completed. After the mining of the stage mine is completed, the whole tailings are cemented and filled. The ratio of sand to sand at the bottom of the stope is 1:4, and the ratio of sand to sand in the upper part of the stope is 1:8. The second step is to return to the mining column and the pillar is finished. After that, the whole tail sand is filled with low-strength cement; some waste rock is filled into the gob and filled with the filling slurry, and the stope does not filter water. Before the filling, the goaf needs to be installed with a filling retaining wall to close the gob.
2.6 Main technical and economic indicators
The main mining technical and economic indicators of this test are as follows:
The production capacity of the stope is 800t/d;
Cutting ratio of 4.1m/kt;
Mining depletion rate is 10% to 12%;
Mining loss rate is 12% to 15%;
The unit cost of filling is 79.89 yuan / t.
3 conclusions
(1) In the medium-solid ore body, the mining method after the mining method in the staged rock drilling stage can safely and effectively recover the safety pillars and improve the recovery rate of the ore.
(2) The filling strength of the full tailings cementing filling reaches 2MPa or more, which has a good effect on controlling the surrounding rock pressure and protecting the surface structures, and also eliminates the safety hazards such as the debris flow in the stope.
(3) Filling with full tailings cement, sufficient filling materials, at the same time alleviating the inventory pressure of the tailings pond and reducing the construction investment of the tailings pond.
references:
[1] Li Chunlei, Cai Meifeng, Li Xiaotong. Prediction of mining subsidence in sublevel caving without pillars [J]. China Mining, 2006 (12): 45-47.
[2] Yang Hongbao. The silver ore cement lianjiang Experimental studies [R] filling method of tailings to the intake passage. Changsha: Changsha Mining Research Institute Co., Ltd., 2006.
[3] Party Peak, Zhang Zichao, Yang Yuxue. Analysis of the influence of tailings cement filling method on the stability of surface building facilities [J]. Modern Mining, 2013 (8): 26-29.
[4] Li Xingshang, Wu Fachun, Xu Jialin. Optimization study of upward horizontal stratified filling mining method [J]. Metal Mine, 2006 (4): 16-18.
[5] Zhu Xing, Lu Jun, Liu Yugang. Research and application of full tailings cement filling technology [J]. Hunan Nonferrous Metals, 2013, 29(5): 5-7.
Article source: Mining Technology: 2015, (15) 6;
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