Former Soviet Union mining inclined ore body column

Soviet Union西卡拉扎尔iron ore deposit is an inclined, angle 30 ~ 42 °, a thickness of 16 ~ 35m. The ore is magnetite-hematite with an iron grade of 50-55% and f=6-15. The roof is mineralized stone and lean ore, allowing an exposed area of ​​up to 20,000 m 2 and an iron grade of 16% to 35%. The bottom plate is silicified limestone.
The mining method of the explosive force mining stage is adopted. The parameters of the explosive force mining are: when the inclination angle of the ore body is 25 to 30°, the explosion force transportation distance is 25 to 30 m; when it is 30 to 35°, it is 40 to 50 m; and the 35 to 40° is 65 to 70 m. According to this, the following structural parameters are adopted at the 230m and 290m levels: 60m wide along the strike block, the mine block divides two mine houses, the width is 20~25m, the room pillar width is 8m, the column width between the blocks is 12m, the mine room The slant length is 40-80 m, and the column width is 10 m between stages. The pillars account for 49% of the total mass of the ore. The inclined rock drilling patio is arranged along the center line of the ore block. From 2.5 to 3.0 m, the blasthole spacing is drilled, and the upward fan-shaped hole with a hole diameter of 100 mm is drilled to the lower part of the mine. mine. Use Bgny-4TM vibrating ore concentrator or 21C-28, 21C-55 type electric shovel to mine.
The ore recovery rate of the mine can reach 86% to 94%, but the ore recovery rate is only 30% to 35% when the ore is collapsed to the empty mines on both sides. Forced caving of the roof of the mine (the height of the collapse is not less than the thickness of the ore body). The mining of the bottom funnel can increase the recovery rate of the pillar, but the cost of the roof is higher, and the cutting work is also larger (up to 5.4 m/kt). The electric raft has poor working conditions in the inclined tunnel and has poor safety. To this end, the forced-natural collapse roof and the end-stage ore-distribution sublevel caving method are used to recover the inter-column. First, the local breakout force mine roof pillars adjacent plates to make the free surface of the inter-column 5m thick stone caving of roof (FIG. 1). With this method, the cost of empty field treatment can be reduced by 50% to 75%, the recovery rate of ore can reach about 70%, and the depletion rate is 10%, which improves the mechanization degree of mining and operation safety and reduces mining cost.

Fig.1 Columnless sublevel caving method
A—a schematic diagram of the collapse of the roof rock by a forced natural collapse method; a schematic diagram of the b-inter-column recovery;
I~III—The fine blasting sequence of the collapsed roof. I is the roof of the mine that partially collapses against the pillar.
II is the rock on the top pillar of the collapsed mine, and III is the rock on the collapse column.

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