The system of floor forced caving is widely used in the development of powerful, vast deposits. Representing a complex complex of mutually influencing and conditioning each other parameters and processes, in their compliance with mining geological and mining conditions, this system provides high labor productivity and low cost of ore extraction. ...
The methodology and results of laboratory studies of the process of collapse of overlying rocks are outlined. The researches are executed in the Leningrad Mining Institute for conditions of development of apatite deposits of Khibiny, hanging side of which is represented by strong fractured rocks.
Outstanding scientist in the field of underground development of mineral deposits, Professor, Doctor of Technical Sciences, Head of the Department of Development of ore deposits of the Leningrad Mining Institute Vladimir N. Semevsky was born in 1898. After graduating from high school from 1918 to 1922, a Red Army fighter he defended the western borders of the young Soviet Republic.
In the development of horizontal or declining ore deposits to improve the conditions of ventilation, prevent the penetration of water and gases, localization of cave-ins and other purposes it is sometimes necessary to leave barrier pillars that divide the ore body into separate fields. In case of significant ore reserves, these pillars are sometimes extracted after mining of adjacent fields...
Mining of ore deposits in conditions of increased mining pressure is often associated with dangerous stress concentrations that can cause harmful consequences for production: deformation of workings and separate sections of the ore body, crushing of pillars, self-collapse of ore and other phenomena that increase the danger of work, losses of minerals, labor and cost.
At Apatit mines, as a rule, the upper part of ore deposits is exposed to the day surface. During the underground development of blocks of upper horizons is often observed self-collapse of the massif, freezing of the beaten ore, scattering of its explosion. This leads to large losses of ore ...
The disseminated copper-nickel ore deposit developed by the Zapolyarny Mine is represented by a gabbro-diabase deposit up to 30 meters thick, dipping at an angle of 12-20°. Above the ore-bearing intrusion lie effusive rocks (porphyrites, gabbro-diabases) with a total thickness of 180-250 m.
It is known that mass explosion of ore by boreholes or mine charges under the system of forced storey collapse can be carried out on preformed compensation chambers or without them. The latter method - one-stage ore stripping in a clamped environment - is currently used at the apatite mine named after S. M. Kirov. S.M. Kirov apatite mine, Zapolyarny mine of Norilsk Combine, Salair mine, mine named after XXII Congress of the CPSU of Zyryanovsky Combine and others. The method of stripping affects the physical and mechanical properties of the stripped ore: if in variants with compensation chambers the coefficient of initial loosening of the ore immediately after blasting the block varies from 1.3 to 1.6, then at one-stage stripping this coefficient varies from 1.1 to 1.3.
The correct choice of the direction of the clearance excavation largely determines the amount of bearing pressure on the pillars and the ore massif adjacent to the excavated space, and the manifestations of bearing pressure determine the safety of excavation and the amount of ore losses. This factor becomes especially important in the development of fractured unstable ores. The Norilsk copper-nickel deposit develops mainly disseminated ores, which are mineralized gabbro-diabases. Some sections of the lower part of the ore body contain continuous sulfide ores.
The study of rock pressure on models with quantitative measurement of loads is a rather difficult task. In order to obtain satisfactory results it is necessary not only to select a model material that meets the specific conditions, but also to have reliable measuring equipment. Dynamometer base was first applied in 1955 in the All-Union Coal Institute (V.G. Bochkarev), and then in the Institute of Mining Engineering, USSR Academy of Sciences, and some experiments were conducted by VNIMI.
The economic significance of qualitative and quantitative mineral losses during mining is well known, and therefore the importance of their regulation is obvious. Although mineral losses and dilution during mining are inevitable, their size can be different, and the possibility (and the degree of technical complexity) of reduction depends, on the one hand, on natural conditions, and on the other hand - on the development system, the quality of mining operations and the quality of their control and accounting.
