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Self-igniting deposit mining example 1 - Songshanshan mining area, Tongguanshan Copper Mine
Ore body conditions. Pine Mountain School warmed liquid metal ore contact metamorphic skarn copper ore, ore bedded, angle 23 ~ 46 °, the horizontal thickness is generally 5 ~ 10m, for most thick 25m, 420m long strike, the bottom plate It is a corner shale , medium stable, and joint development. The roof is made of marble , and the shallow part is weathered into a muddy point of Dali rock block, which is extremely unstable. Copper ore pyrite, pyrrhotite, chalcopyrite, jelly, sponge-like pyrite, average sulfur content of 13.4%, up from 38% to 47%, the degree of deep oxidation of sulfide minerals in the ore more concentrated The primary secondary sulfide-enriched sub-band and semi-oxidized ore sub-belt are loosely structured and self-igniting, especially near the old mantle and fault.
Mining and fire conditions. In 1954, the horizontal stratified caving method was adopted for the false-topping of the wooden board. After the open space was opened, the temperature rose by more than 40 °C, and toxic gas such as SO 2 was released, and a spontaneous combustion fire occurred soon. In 1956, it was forced to close and switched to the stratified caving method of preventive yellow mud grouting. The drilling blockage did not achieve the intended purpose. In 1958, the closed wall was opened to try to resume production. Soon the temperature rose again and it was closed. Beginning in 1959, the lower stage nuggets, which were relatively stable and not very hot, were selected, and some of the mines were recovered by horizontal stratified dry filling. In order to reduce the exposure time of the ore bodies in the air, they were used in the floor shale. Arrange the mining lanes and do not expose the ore during the mining phase. At the time of mining, the "three strong" technical organization measures were adopted, and each time the mining was carried out less quickly, and the ore was taken out before the ore was fired, thus basically solving the mining problem of the ore with serious fire.
The components of the subsection caving mining method are shown in Figure 1.
Figure 1 Tongguanshan vertical sectional sublevel caving mining method
1—Electric sluice roadway; 2—Funnel; 3—cutting roadway; 4—rock drilling chamber; 5—gun hole; 6—Pedestrian patio;
7—Importing wells; 8—slope roads; 9—through-vehicle transportation lanes; 10—transportation along the veins; 11—panning pillars
Appropriate layout. According to the dip angle of the ore body, there are two kinds: when the inclination angle is less than 25°, the length of the 40m electric raft is arranged at 5m away from the ore body at the bottom of the ore body, and the concentrating funnel is staggered along the sides of the electric raft, with a spacing of 5m. The mining sequence is carried out from top to bottom along the inclined direction of the ore body. The mining method adopts shallow hole cutting slot and medium and deep hole extrusion blasting. When the ore body thickness is greater than 10 m, deep hole extrusion is used to blast the ore. Strictly control the amount of collapsing once, each time it is controlled at 1000-1500t, adopt the "fast mining and fast-out" intensive mining measures, and rush out the mine before the fire period.
Ventilation Ventilation uses a mixed partition ventilation that is centrally pressed into the two wings. The ventilation system is shown in Figure 2.
Figure 2 Ventilation system of Songshushan mining area in Tongguanshan Mine
The fresh air is pushed in from the inclined shaft, and the road surface is taken from the bottom hole to the lower part of the roadway → the electric roadway → the upper stage outer diameter return roadway → the surface is extracted from the wind well.
The roadway of the stope is full-section through the wind, and the wind speed is 0.8m/s. The ventilation network of each stope is serially connected in series, that is, several electric roadways are connected in parallel along the pulse. Due to the enhanced ventilation and avoiding the series air flow of each stop, it is beneficial to reduce the working surface temperature and dilute the toxic gas concentration. In addition to timely closing the goaf and the old roadway, the working surface temperature can be kept below 28 °C, and the relative humidity is 80% to 90%, octave 4 to 7 degrees.
Blasting in high temperature mining. The blasthole temperature is determined multiple times before blasting (and the sampling test conforms to the self-explosion condition). When the pore temperature exceeds 80 °C, the explosive is packaged in double-layer kraft paper coated with asphalt , and then wrapped with glass cloth outside, or wrapped in a high-temperature plastic bag to prevent the explosive from directly contacting the ore and causing self-explosion. It is required to shorten the blasting operation time as much as possible, and make all preparations before charging. Each blasting is required to be completed within 2 to 4 hours. Pay attention to the high-temperature blasthole in the final charge, and do not fill the mud, in order to observe the presence of smoke before self-explosion, to ensure safe operation.
After the high temperature area is finished, it is necessary to close the electric roadway and the funnel in time, and it is not allowed to open it casually, reduce the air leakage to the goaf, and prevent the high temperature dust and high temperature toxic and harmful gas accumulated in the mining area from being suddenly sprayed and wounded.
Technical and economic indicators. The production capacity of the stope is 180t/d; the mining ratio is 230m/ton; the excavation efficiency is 0.45m/work; the mining efficiency is 45t/work; the deep hole is 11m/set; the medium and deep hole is 1.7m / TAIPAN; the hole stope 6t / m dilution ratio of 18%; 14% loss; explosive consumption 0.45kg / t; prop consumption 45 m 3 / tons.