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Application of underground mining in rock gold deposit-wall explosive force mining
Tongguan gold mining ore column space original method, when the thickness is less than ore mining web, using commingled ore, a high dilution rate. In order to solve this problem, the wall-type explosive force mining comprehensive mining method was successfully studied and successfully applied, and it was applied in the ore body with thickness of 1~1.6m.
First, mining technical conditions
Tongguan gold ore body to the configuration with the quartz pyrite, quartz veins as veins or lenticular in configuration with distribution in the wavy soothing orebody strike and dip, there is expansion and contraction, complex branch, to tip Reproduce and other phenomena. The length of the continuous ore body is about 50-200m, the thickness of the ore body is about 0.5-2.7m, and the inclination angle of the ore body is 3°-10° (401 vein) and 10°-18° (505 vein). The surrounding rock of the ore body is mainly mixed with slanted gneiss and hornblende gneiss, most of which have good integrity and local cracks develop. The ore hardness coefficient is mostly f=8~10, which is stable. The surrounding rock f=10~12, medium stable.
Second, mining method structure and mining cutting
The nuggets are 50m long along the strike and 40-50m along the slope. A 2m wide continuous pillar is placed between the two nuggets to isolate the wall face of the goaf. At the bottom of the nugget, along the ore body, the tunnel is drilled. From the extra-vehicle transport roadway, the mine slipper is communicated with the mine block communication road every 6~6.5m, and the electric winch winch chamber is excavated. The mining method structure and the mining engineering arrangement are shown in Figure 1.
Fig.1 Schematic diagram of the comprehensive mining method for the wall-type explosive force mining in Shaoguan Gold Mine
1—Transportation roadway; 2—mine slip; 3—rock pillar; 4—seeking uphill; 5—returning lane;
6—cutting up the mountain; 7—mineral column; 8—contact line; 9—electric winch winch chamber; 10—pillar;
11—throwing blasthole; 12—falling blasthole; 13,15—to be mined; 14—rock trough; 16—metal mesh
Third, mining work
The mining work starts from cutting up the mountain and is pushed from one side to the other. In the oblique direction, the tilt is pushed from the bottom to the top. The mining width (about 1.8m) is divided into upper and lower parts, the upper part is the ore body and the lower part is the rock mass. At the time of mining, the rock mass of the lower mining frame is firstly produced by throwing blasting method, a rock trough is formed on the working surface, and after the residual rock is manually cleaned to the pillar, the metal mesh is hung on the pillar, and then the ore body in the mining body is recovered. This is divided into points.
(1) Rock throwing
The angle between the projectile and the working face is about 42°, the depth of the eye is 3.0m, the eye distance is 0.5m, and the row spacing is 1m. When the medicine is loaded, the medicine roll is cut into a high-density charge, and the non-conducting squib is slightly detonated. 80% to 90% of the rock can be thrown into the goaf beyond 3m, and the rock remaining on the bottom plate is manually cleaned to the outside of the first row of pillars to form a rock tank with a width of about 1.5m. The cost of rock-burning explosives is 0.7-0.8 kg/t.
(2) Falling mine
The vertical working face of the falling mine blasthole is well played at the same time as the rock blasting. The depth of the eye is 1.8 to 2 m, and the eye distance is 0.6 m. The blasthole plum blossoms are arranged. Manual charging, non-conducting squibs are slightly detonated. In order to prevent the ore from collapsing into the goaf, a metal mesh is hung on a row of technical columns near the working surface before blasting. The metal mesh is made of No. 8 wire, each piece is 0.8m×1.5m, and can be recycled and reused with the advancement of the working surface. The mining explosives consume 0.3 to 0.35 kg/t.
(3) Mining
The ore of the working face is transported to the discharge funnel by electric shovel, and is transported out by the mine slipper. The power of the electric raft is 30kW, and the volume of the bucket is 0.3m 3 .
(4) Roof management
Mainly use the column technical protection roof. Install a row of columns at a distance of 3m from the working face, and then advance the working face for 1.5m. Just support a row of columns. According to the stability of the top plate, the number of rows of the column is determined, generally 3 rows are reserved, and in the fourth row, the first row of pillars farthest from the working face is recovered. The column spacing in each row of pillars is 2 to 2.5 m. The column can be used with wooden posts or lead metal posts. The recovery rate of wood column is 75%, and the recovery rate of screw column is 80%. If the top plate is partially unstable, it can be reinforced with anchors. In addition, non-industrial blocks are also reserved for the pillar support roof.
The roof of the goaf allows it to collapse on its own without further treatment. Because the ore body is thin, the inclination angle is small, and there are non-industrial blocks supported by the pillars, it is not easy to occur in large areas at the same time. However, for local areas, if the pillars are under great pressure and threaten the safety of the working surface, and the roof cannot collapse on its own, local forced ceiling measures can be taken to eliminate potential hidden dangers.
Fourth, technical and economic indicators
The main technical and economic indicators of the test nuggets are listed in Table 1.
Table 1 Main technical and economic indicators of mining methods
Indicator name
Numerical value
Indicator name
Numerical value
Production capacity of ore block /t·d -1
40~50
Explosive consumption / kg · t -1
0.63
Acquisition coefficient /m·kt -1
20
Pit wood consumption / m3 · t -1
0.0048
Ore loss rate /%
6
Ore direct cost / yuan · t -1
13.5
Ore depletion rate /%
11.5
V. Evaluation
The main advantages of this method compared to the original house and pillar mining method are:
(1) The ore loss rate and depletion rate were significantly reduced, the ore loss rate was reduced from 20% to 6%, and the ore depletion rate was reduced from 28% to 11.5%.
(2) Due to the classification of mineral rock, some non-industrial ore bodies (thickness or low grade) that do not reach the minimum industrial grade can be converted into industrial ore bodies to increase industrial reserves.
(3) Due to the classification of ore and rock, the rock remains in the goaf, which reduces the transportation cost and the processing cost of the beneficiation . The main disadvantages are:
1. The process is relatively complicated, especially for the rock blasting construction technology of rock throwing, which must be strictly in accordance with the design and construction. Roof management is also more complicated.
2. It is impossible to throw the rock into the goaf completely by throwing the rock. The remaining rock is manually cleaned, which is time-consuming and labor-intensive and labor intensive.
3, pit wood consumption is more.
Applicable conditions of this mining method: gently inclined thin ore body, the thickness of the ore body is 1 ~ 1.6m; the roof is moderately stable; the boundary of the ore is obvious.