Delivery of the ore using the explosion

(Figure) The delivery of the ore using the explosion / The delivery of the ore using the explosion: 1 - the mine working for the drilling of the boreholes (the drilling raise); 2 - the borehole; 3 - the mine working for the receiving of the broken ore; 4 - the drift for the forming of the cut-off crevice; 5 - the mine working for the loading of the ore.

(Figure) The delivery of the ore using the explosion
The delivery of the ore using the explosion:
1 - the mine working for the drilling of the boreholes (the drilling raise);
2 - the borehole;
3 - the mine working for the receiving of the broken ore;
4 - the drift for the forming of the cut-off crevice;
5 - the mine working for the loading of the ore.

DELIVERY OF THE ORE USING THE EXPLOSION (EN: blasting ore transport; DE: Explosiverztransport, Erzversetzung durch Sprengung; Schießtransport des Erzes; FR: desserte de minerai par tir; ES: mineral transportado por la voladura; RU: взрывная доставка руды) is the movement of the ore within the limits of the excavation place of the underground mine to the receiving horizon on the account of the energy of the explosion. They use this method at the inclined and flat depositions with the thickness from 3 to 30 metres, less often 1.5-3 metres. The delivery of the ore using the explosion has been proposed within the USSR during the 1956 for the development of the inclined depositions using the underground method; this method has been used for the first time during the development of the Mirgalimsai deposit (the angle of inclination of the ore body is 30-55 degrees).

The delivery of the ore using the explosion is performed within the excavation places (chambers, or panels) with the width of 12-15 metres on average, which are situated along the dip of the ore bodies, and which are processed from the bottom to the top. During this process, the ore is moved using the force of the explosion above the soil of the exposed stope space through the distance of 30-40 metres with the angle of inclination of the deposition of 15-20 degrees, and through 60-80 metres with the angle of inclination of 30-40 degrees. The delivery of the ore using the explosion excludes the presence of the people within the stope space. They break the ore in the layer-wise manner, using the explosions of the charges with the explosive substances within the boreholes, which are drilled from the raises (see the Figure), which pass through the ore body near the footwall with the deepening of 0.5 metres into the country rocks (for the possibility of the drilling of the boreholes along the contact with the country rocks).

The true angles of inclination for the boreholes are determined according to the formula:

sin(g) = cos(a) • sin(b)

(g is the true angle of inclination of the borehole to the horizontal plane; a is the angle of the dip of the ore body; b is the angle of inclination of the borehole to the horizontal within the plane of the fan).

In association with the relatively small volume of the drilling works within each fan, and with the necessity of the redeployment of the equipment within the inclined mine workings, during the delivery of the ore using the explosion, there is most effective the usage of the movable drilling machines.

There is suitable the usage of the charging devices with the flexible hose, which has been laid from the upper horizon through the raise. The specific consumption of the explosive substance during the delivery of the ore using the explosion is adopted the same, as during the breaking under the normal conditions, or is increased by 15-25% on the account of the additional contouring charges, and of the certain thickening of the mesh of the boreholes. During one cycle, they explode 1-2 fans, with the slowing of the second fan usually for at least 50-100 milliseconds; they explode during the last cycle the boreholes, which are situated near the soil of the excavation place.

The voluminous capacity of the mine workings of the receiving horizon must ensure the placement of all the ore, which has been broken during the one explosion. If the major portion of the ore, which is being broken, is moved using the force of the explosion, then the remaining portion of this ore on the soil of the excavation place, after the accumulation, is transported to the receiving horizon, using the bulldozers or scrapers, which are remotely controlled; there is possible the hydraulic movement of the ore. Within the depositions with the average and above average thickness, with the angle of the dip of more than 25 degrees, the delivery of the ore using the explosion is performed without the usage of the additional means for the cleaning of the soil within the excavation places. In case of the thickness below the average, and the angles of the dip less than 25 degrees, the usage of the delivery of the ore using the explosion permits us to obtain the concentrated pile of the mining mass within the specified place (for example, within the mine workings for the scraping), to conduct the selective excavation with the directional throwing of the waste rock into the goaf space. In case of the delivery of the ore using the explosion, the productive capacity of the excavation place is 5-15 thousand tonnes per month. The distance for the effective delivery of the ore using the explosion (25-80 metres) decreases with the decreasing of the thickness and angle of the dip of the ore bodies; the effectiveness for the delivery of the ore using the explosion increases with the growth of the sturdiness of the ore.