Abstract
Control and regulation of the formation behavior while using the uncontrolled caving method require thorough investigation of the formation properties and structure, its geological, geostructural and geotechnical parameters as well as geomechanical peculiarities of rock pressure generation and its effect in the course of ore deposits mining.The most indicative are the mining plants of Donskoy Mining and Concentration Complex, which operate the uncontrolled caving method for mining of thick ore deposits at the chromite ore fields.The fields of South-Kem pirsay chromite-bearing block are the second largest fields comparing to Republic of South Africa and Zimbabwe. Prospectivity and extent of the operations at the fields could be described by the rate of production and its development: Molodyozhnaya mine of 2.0 million tons annual output is the world largest underground mining of chromite ore.Currently mining of ore deposits at Donskoy chromites fields is carried out at rather significant depths (of 500 and more meters), the second working of subjacent strata is carried out as well.Along with the extension of second working areas under the specified conditions, carrying out of the large-scale development operations and pre-production development as well as generation of closed extraction mines, there is the necessity to ensure more rational regulation of the rock pressure, provision for safe structural components of the mining system, selection of the methods and means for mine workings fixing and, finally, provision of efficient and reliable system of ore deposits mining. In applying this system it is critical to determine the caving zone sizes, which could be calculated quite easily depending on the ore body parameters, direction and sequence of its reserves development, whereas its height would depend on the extent of the increase of the caving rock block volume due to its loosening. This article outlines the results of laboratory tests on determination of the volume of loose rocks, which is calculated on the basis of the loosening factor (kр) that represents the ...ratio of the rock volume in loose (bulk) state to its volume as the solid block….
Highlights
Speed-up of the scientific and research progress as well as the development of Kazakhstan economy are anticipated to happen due to the increase of the resources mining efficiency along with the enhancement of working conditions and ensuring safety thereof, increase of ore reserves extraction from the subsoil and reduction of adverse impact of mining operations on the stability of the underworked formation atop of which the industrial and civil buildings are located
It is critical to explore the essence of these phenomena and, with regard to geomechanical processes regularities, make the justified decision on the control methods of the technological mining scheme, determine all required mine engineering parameters
In developing the flat-laying ore bodies of Donskoy chromite fields at 800-1200m depth (“Millionnoye” field, ore bodies 2; “Almaz-Zhemvhuzhina”, ore bodies 3, 4, 7) for which uncontrolled caving of ore is typical at the relatively small ore bodies sizes in terms of depth (80-150 m) and thickness of 40-100 m, it is very probable that the caving zone will not outcrop, and the roof arch will stop propagating as soon as it reaches its certain height due to “self-cleavaging” with loose rocks
Summary
Speed-up of the scientific and research progress as well as the development of Kazakhstan economy are anticipated to happen due to the increase of the resources mining efficiency along with the enhancement of working conditions and ensuring safety thereof, increase of ore reserves extraction from the subsoil and reduction of adverse impact of mining operations on the stability of the underworked formation atop of which the industrial and civil buildings are located. In developing the flat-laying ore bodies of Donskoy chromite fields at 800-1200m depth (“Millionnoye” field, ore bodies 2; “Almaz-Zhemvhuzhina”, ore bodies 3, 4, 7) for which uncontrolled caving of ore is typical at the relatively small ore bodies sizes in terms of depth (80-150 m) and thickness of 40-100 m, it is very probable that the caving zone will not outcrop, and the roof arch will stop propagating as soon as it reaches its certain height due to “self-cleavaging” with loose rocks. Intensive fracturing of the rock massif would contribute to this, when superincumbent rock caving follows the uncontrolled caving of the ore massif without significant retention and formation of the natural arch according to the generally accepted concept (when the rock caving process may cease providing availability of free space under this arch)
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