Bolt top throwing blasting room column mining method

The gold ore deposits Tongguan their condition were studied bolt precontrol top casting blast room and pillar mining method.

I. Technical conditions for mining ore mining

The test nugget is No. II nugget in the middle section of No. 505 vein 1498m. The thickness of the ore body is 7-15 m, and the inclination of the ore body is 15°. The surrounding rock of the upper and lower plates is a biotite slanting gneiss , Æ’=12～14, the surrounding rock is close to the surface, affected by weathering, moderately stable. Ore Æ’ = 8 ~ 12, joint development, medium stability. The ore and rock weighs 2.7 t/m ³ . The loose coefficient is 1.7. The ore has a gold grade of 7.89 g/t. The purpose of this test is to study the mining method of gently inclined medium-thick ore bodies under moderate stability conditions of surrounding rock.

Second, mining method structure and mining cutting

The length of the test ore along the ore body is 26m, of which the width of the mine is 12m and the width of the pillars on both sides is 7m. The ore block is 32m along the inclined length. The mining method is shown in Figure 1.

Figure 1 Shaoguan gold mine anchor pre-control top throwing blasting room column method

1—transport roadway; 2—electric roadway; 3—receiving ditch; 4—bucketing; 5—cutting alley;

6—cutting the patio; 7—rock drilling roadway; 8—ventilation contact roadway; 9—contacting the patio; 10—cutting the roadway;

11—Exploration Patio; 12—Bolt; 13—Returning to the Pillar Rock Drilling Lane; 4～10—Blast Hole Row

At the stage transportation level, an external electric roadway is arranged along the lower part of the ore body, and this roadway is used as a mining roadway for mining houses and pillars. From the electric roadway to the mine, the funnel is worn and the well is drilled, and each well is connected to form a mine ditch. From the level of the mine entrance along the center line of the mine, the middle and deep hole rock drilling roadway is drilled in the middle of the mine floor and crosses the ventilated roadway arranged in the upper part of the mine. At the level of the mine, along the ore body, the cutting and cutting lanes are ploughed, and the cutting patio is digged in the central position. From the upper part of the cutting patio, the cutting roof roadway is drilled along the roof of the ore body at the center line of the mine house, and is connected with the communication patio tunneled by the ventilation contact roadway. After the penetration, it is widened to the top of the whole mine, and the top of the mine is cut with the surrounding rock of the roof. The height of the cutting roof is about 2m, and then anchored with metal anchors.

The cutting groove of the mining room is located at the location where the cutting alley and the cutting patio are located, where the ore joints are developed and have caves, and the stability is not good. A medium-deep hole and a shallow eye are combined with one blasting groove.

Third, mining work

(1) Falling mine

Mining in the mining area, deep hole throwing and blasting. Drilling deep holes in the rock drilling roadway, the blasthole row is inclined forward by 75°, fan-shaped arrangement, the minimum resistance line is 1.6m, the hole bottom distance is 1.8m, the blasthole depth is generally less than 10m, and the hole bottom distance is 0.3~0.5m from the cutting space. . The rock drilling machine adopts the YGZ-90 rock drill and is equipped with the FJY-25 snow truss. The diameter of the bit is 60 mm. The blasthole is manually charged, the medicine roll is 50-55mm, and the charge factor is 0.7-0.75. The non-electrical differential detonator and the detonating cord are used for detonation. The unit explosive consumption is 0.48kg/t. The blasthole collapse amount is 4.6t/m. A total of nine medium-deep hole blastings were carried out in the mining recovery. The ore throwing of each blasting is shown in Table 1.

Table 1 Effect of mining and mining throwing blasting effect

As can be seen from the table, the throw rate decreases as the throw distance increases. In order to improve the effect of throwing blasting, the following measures are taken: (1) to control the number of rows per blast, generally one row per blast, and if two rows are blasted, the delay time of the second row is not less than 50 to 100 ms. In order to allow the front row of blasting to make room for the rear row of blasting; (2) the side holes of each row of deep holes close to the bottom plate are required to be on the same slope to ensure that the slope of the floor is flat, which is conducive to ore rolling; (3) before each blasting Clean the ore remaining on the floor of the mine.

(2) Mining

Due to the throwing blasting of the mine, most of the ore (accounting for 69.1% of the ore mined in the mine) has been thrown into or rolled into the ore trench during blasting. Before each blasting, the ore remaining in the bottom of the mine is transported by electricity to the mine ditch. The ore in the trench passes through the electric tunnel and is transported to the loading station for loading. The electric boring loading platform is used to arrange the electric roadway and the stage transportation roadway at the same level, which reduces the height of the bottom column and reduces the amount of mining work.

(three) roof management

The roof of the mine is mainly supported by the pillars on both sides. Before the mining house is harvested, it has been cut with the surrounding rock of the roof and anchored to the roof with anchors. The anchor used is an expanded metal anchor with an anchorage of (1.0~1.2) m×1.0m and a boundary anchor of 0.3m from the pillar. The pre-control measures of the anchors ensure that no roof fall accident occurred during the mining period.

(4) Pillar mining

The width of the pillars on both sides of the mine is 7m, and the pillar mining method is adopted in the middle and deep hole falling ore funnel scheme. An electric roadway and a funnel are arranged in the surrounding rock of the bottom of the pillar. At the junction of the pillar and the bottom plate, the rock-filling roadway is drilled in each of the cross-rocks. In the rock-boring roadway, the YGZ-90 rock drill and the door Y-25 type rig are used to drill the deep hole, and the blasthole is fan-shaped. as shown in picture 2.

Figure 2 Deep hole falling ore chassis funnel back to the mining column

1—Transportation roadway; 2—Electric sluice roadway; 3—Pillared column mining electric shovel; 4—Chassis funnel; 5—Cutting roadway;

6—cutting the patio; 7—mine mining and rock drilling roadway; 8—mine mining back blasthole; 9—mine mining goaf

Fourth, technical and economic indicators

The main technical and economic indicators of the Shaoguan gold mine test nuggets are shown in Table 2.

Table 2 Main technical and economic indicators of test nuggets

V. Evaluation

This mining method is used to mine the gently inclined medium-thick section of No. 505 ore body of Shaoguan Gold Mine, showing the following advantages:

(1) The mining room and the pillar mining application use deep holes, and the rock drilling and blasting operations are carried out in the roadway, and the working conditions are safe.

(2) Before the mining, the roof is cut with the surrounding rock of the roof, and the roof is fully reinforced with the anchor to ensure that the roof does not fall during the mining.

(3) The application of medium-deep hole ore mining is more efficient than shallow-eye mining, and the amount of primary mining is large.

(4) Applying throwing blasting, most of the ore is transported to the ore sump by means of explosive force.

(5) The mining capacity is high.

The main shortcomings of the mining method are: the process is more complicated, and the design and construction requirements of the medium and deep holes are relatively high. The ore of the residual bottom plate after the blasting is thrown away during mining. The ore loss rate is high.

Applicable conditions of this mining method: gently inclined medium-thick ore body, the ore body inclination angle is greater than 15 °, the ore body occurrence factors are relatively stable and regular, and the ore rock is moderately stable.