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The question of the use of conveyer transport in open-cut ore mines has been much discussed in recent years. This is due to the fact that the wheeled transport (motor and railroad) presently used in such mines requires too much labor to permit an increase in the output per man as the mine depth increases.Complete conveyerization of open-cut mines gives a better output per man than a combination of conveyers and wheel transport, but for this purpose belt conveyers must be installed in the excavator faces and must also be protected during blasting.Strictly formalized organization of blasting which would exclude breakup of the benches and reduce fragment separation to a minimum is the most desirable way of ensuring that the conveyers are not damaged by flying fragments resulting from an explosion.To suppress fragment separation, blasting is performed without a compensation space with use of a support wall of existing spoil rock.The greater the width of the support wall, the smaller will be fragment separation, but the greater will be the width of the bench area and the lower the possible output of the mine owing to the decrease in the number of benches. It is therefore necessary to determine the minimum width of the support wall sufficient for maximum reduction of exploded rock fragment separation.Eleven observations on fragment separation at different support wall widths have been performed in Krivoi Rog mines by the Institute of Mining of the Ministry of Ferrous Metallurgy of the USSR.The Krivoi Rog open-cut mines work ferruginous quartzltes with a Protod'-yakonov hardness of 12-18.Extensive blasting operations are performed with zernogranulit with a specific consumption of 0.6-0.9 kg/m'. Control areas were established at a distance from the block being blasted; after a massive explosion, the number of rock fragments thrown by the explosion on these areas was calculated and their weight was determined.The control areas were cleaned-up sectors of railway track or roadway, along with a polyethylene film specially spread at a distance of 40-80 m from the explosion. Table i lists the results of field observations on fragment separation; the effect of the support wall can be seen.In the case of explosions without a support wall the mean frequency of fragment incidence on the control area was 1.020 fragments/m ; with the use of a support wall 16-30 m wide, this figure was reduced by a factor of ii to 0.096 fragments/m2; with a wall width of 60 m the figure was 0.017 fragments/m 2, or a decrease in the first value by a factor of 61.The explosions of group II (with a support wall 16-30 m wide) show that the frequency of fragment incidence varies markedly (from 0.02 to 0.244 fragments/m2), but no specific dependence of the frequency on the dispersion distance is observed.The mean frequency of frag-9 ment incidence is 0.096 fragments/m 2, which on conversion to a conveyer belt width of 1.2 m gives a relative frequency of fragment incidence on the belt of I fragment per 9 m of conveyer length.According to Table i, the mean w...
COMPUTER STORAGE OF M. V. Vasil'ev, V. and M. N. Sivkov MINING=GEOLOGICAL M. Alenichev, INFORMATION UDC 622.235.6:551.252The use of present computing techniques in the planning of open=cut mining operations is greatly hindered by the lack of simple methods of representing mining=geological, technical, and technological information, the amount of which is of primary importance in the adequate representation of the real situation. Changes in the technical and technological conditions of mining at the preplanning stage of assessment are comparatively easily stored in the computer by correcting the initial data. But each change in the geological information requires a reworking of the graphical material represented in the geological survey documentation (lateral and longitudinal geological cross sections, and in some cases horizontal plans). In this case it is extremely difficult to make full use of the main advantage of computers -their rapidity of action -in solving technical problems.In solvinga geometrical problemwith a computer, in the machine we must store a mathematical model of the deposit which completely reflects the geometrical, structural, and qualitative properties of the mineral and rocks. We must mathematicaUy describe the spatial parameters of the deposit and the laws by which they change during the working of the beds. The method of representation of the original geological information and the mathematical description used in the model of the spatial elements of the quarry or open pit determine the algorithms used for access to the machine storage to get the necessary data for solving the problem.At present there are about 20 models for representing geological information in a computer: they differ in their fields of application (according to the shape of the deposit), in the methods of mathematical representation of the deposit and pit and their relation (combination), in the amounts of initial information used, and in the precision and cumbersomeness of the calculations (Table 1).The separate method of modeling consists in compiling independent models of the deposit, the development of mining operations, and the outline of the pit. The initial material for the construction of the models consists of data from survey boreholes, hypsometric and horizontal plans, and transverse and longitudinal geological cross sections. The processing of the information can be divided into several independent parts. Geological, technological, and technical information are prepared independently of one another, and this makes the process of preparation more accessible for the routine processor. In addition, semiautomatic input of geological information is possible with the aid of a special device.
The method of torch guniting developed and introduced in Western Siberia Metallurgical Combine has made it possible to increase to a significant degree the life of converter linings [1][2][3][4]. The production plan provides delivery of the guniting compound to the converter through intermediate vessels, feeders.The loading, discharge, and transportation of the guniting compound is by air or nitrogen.The quality of the coating depends upon correct selection of the ratio of guniting compound and oxygen and constancy of it with time, which is determined by the design of the feeder. A necessary condition of formation of a strong and uniform coating on the lining is maintenance of constancy of the ratio with time of solid and gaseous phases at the outlet from the nozzle (nozzles). This is not obtained in the existing design of feeder~ In feeders with bottom delivery of the guniting compound located in converter shops, with emptying, the flow of guniting compound changes and at the outlet from the guniting torch there is a decrease in the content of solid phase and an increase in the content of the gaseous.As investigations conducted showed, in the old design of 20 m 3 feeder in measurements of the relationship of flow to pressure in the feeder there are wide variations in the flow of guniting compound with emptying of the feeder. For example, with an excess pressure in the feeder of 0.45 MPa in the first i-2 min the flow of guniting compound was 1000-950 kg/min and in the next 3-4 and 5-6 min 750-600 and 600-500 kg/min, respectively.The degree of nonuniformity of flow, characterized by the QI/Q2 ratio (QI is the average flow and Q2 is the rated flow), was for the discharge cycle 0.6. According to literature data [5] for industrial feeders in a broad range of flow of gas carrier the degree of nonuniformity varied within limits of 0.7-0.8.To provide uniform delivery of guniting compound from the feeder and to smooth pulsations in the pneumatic transport system personnel of Western Siberia Metallurgical Combine and the Eastern Branch of the Institute of Ferrous Metallurgy have developed and installed on one of the feeders of No. 5 Converter a device for uniform delivery of powder (Fig. i) [6]. The device operates in the following manner.In loading of the feeder i through a connection the powder material 2 enters into the gap between the round plate 3 and the cone of the bunker and into the cylindrical aeration chamber and fills the volume of the bunker to the plate 3 with the exception of the conical space 5 directly under the plate determined by its area and angle of repose.In unloading of the feeder the aerating carrier gas is supplied through the aerating grid into the chamber 4 and regardless of how full the feeder is the powder located in the feeder immediately changes into a stable pseudofluidized condition since as the result of the presence of the space 5 under the plate 3 the powder has the capability of free vertical movement in the chamber.The pseudofluidized powder flows through the fitting 7 into the fittin...
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