RU2575283C1 - Method of open mining of cryolithic zone fields - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: during the preparation of the next horizon zones of intensive heat exchange in rocks are created in the form of blocks of active climatic influence (ACI blocks) by passing of the roadways serving for the creation of an additional exposed surface of the ACI block. Depending on mining conditions of the field the blocks are arranged lengthways or perpendicular to the direction of development of the front of mining operations. Parameters of the blocks, time of their run are determined taking into account the temperature and climatic characteristics of the area of works, thermophysical properties of rocks, characteristics of mining equipment in interrelation with the degree of weakening of the massif of rocks in the block.

EFFECT: increase of the intensity of heat exchange in rocks.

1 dwg, 1 tbl

Description

The invention relates to the mining industry and is intended for use in open development of solid mineral deposits in the permafrost zone.

The development of mineral deposits in an open way is to create access to the mineral, to remove waste rock covering or containing the mineral, and to extract the mineral itself. That is, open-pit mining is understood as a complex of work carried out from the earth's surface in order to extract a variety of rocks and create various excavations and pits [1-4]. In the process of extracting minerals, an open mined space is formed, which is a set of various mine workings formed in this process, which is called a quarry.

The main elements (characteristics) of a quarry are its depth. On the surface of the earth, the developed space is limited by the boundaries of the quarry field, in depth - by the bottom of the quarry. The development of rocks inside the quarry field is usually carried out in horizontal layers, as a result of which the quarry profile has a stepped shape.

A separate layer, which is developed by independent means of loosening, excavating and moving, is called a ledge. The main elements of the ledge are two platforms (upper and lower), a slope, two edges and a face. The part of the ledge in height, developed by independent means of loosening, loading, but served by vehicles common to the entire ledge, is called a sub-step. The slope of the ledge is the inclined surface that limits the ledge from the side of the worked out space between the upper and lower platforms of the ledge.

The set of different sites and slopes of all the ledges is called the side of the quarry. The side of the quarry, on which mining is carried out, is called the working side of the quarry, in the absence of mining, the non-working side of the quarry. The line of intersection of the sides of the quarry with the earth's surface is called the upper contour of the quarry. The line of intersection of the sides with the bottom of the quarry is called the bottom contour of the quarry. The conditional surface passing through its lower and upper contours is called the slope of the quarry side. The angle formed by the slope of the pit side and its projection onto the horizontal plane is called the slope angle of the pit side.

The disadvantage of this technology of open cast mining in the conditions of cryolithozone deposits is that the direct excavation of permafrost rocks due to their significant strength using earthmoving equipment is often impossible. Their preliminary preparation is necessary. In this regard, the closest in technical essence and the achieved effect is the method of overburden development, including the preparation of the earth's surface (deforestation, river drainage, transport of roads, etc.), mining and capital works (carrying out capital, cut trenches, removal a certain construction volume of overburden rocks for putting the quarry into operation ...), operation period: mining and preparatory work to open the next working horizon-ledge, overburden and mining operations; technological processes in the quarry: preparation of rocks for excavation (drilling, loading, blasting), excavation and loading operations, rock movement (transport of overburden and mineral resources) and dumping, storage and ore sorting in warehouses [1]. In this case, the main methods of preparing rocks for excavation are thawing of frozen rocks, drilling and blasting or mechanical loosening.

Thawing of frozen rocks can be natural or artificial and has found application mainly in the development of alluvial deposits and in some quarries of building materials. These methods of preparation are based on taking into account the known temperature distributions in rocks, depending on the depth at different time periods [5] and the dependences of the resistance of frozen soils to bending, rupture, and compression on their temperature [6].

Natural thawing occurs under the influence of solar radiation. Its intensity depends on the frequency of removal of the melt layer. The removal of the thawed layer by bulldozers or scrapers is carried out over the entire area of the landfill at least 1 time per day. The efficiency of excavating and transporting machines depends on the depth of thawing (the area of cut chips) and on the presence of boulders in thawing loose deposits. The depth and speed of natural thawing of frozen rocks depends on the outside temperature, the composition of the rock and its moisture, and with continuous cleaning of thawed rocks can reach 25-35 cm per day. The natural defrosting method is characterized by simplicity and low cost.

In highly ice-saturated rocks, as well as when it is necessary to create a reserve of thawed rocks, natural thawing with the accumulation of thawed layer is used in autumn. The thawing intensity in this case is lower than with the systematic removal of the thawed layer.

The main method of artificial thawing of frozen rocks is the hydroneedle, which is used mainly for the preparation of pelleted landfills. The use of hydroneedle thawing of rocks in combination with mining and mining-transporting machines allows to intensify mining operations and increases the depth of open development of permafrost placers.

There is also a filtration-drainage defrost, which can be used in preparing rocks for overburden, in cases where the filtration coefficient of loose deposits composing peat exceeds 50 m / day, as well as sprinkling defrost, which is recommended if it is necessary to defrost peat dumps or flushing tailings of past years.

In connection with the ever-increasing capacity of earthmoving equipment, mechanical loosening carried out by bulldozers with cultivating aggregates is widespread.

Drilling and blasting loosening has also found wide application, and not only in fields with sufficiently large volumes of mining operations. Here, depending on mining conditions, drilling and blasting preparation is carried out with borehole or borehole charges.

An analysis of the above analogues [1] shows that the open pit mining of mineral deposits with preliminary preparation of permafrost for excavation in various ways (including using solar insolation) is widely known.

Despite many years of successful experience in opencast mining in the harsh climatic conditions of the North, using generally accepted classical elements of a quarry, methods of preparing rocks for excavation, the efficiency of opencast mining can be improved by making better use of the effects of solar insolation inside the quarry.

The fact is that all the above mining techniques and methods of preparing permafrost for excavation in the North, using well-known elements of the quarry space, have one common drawback: the positive effect of thawing, softening of the massif under the influence of solar insolation is carried out by using one or two outcrop surfaces: usually a polygon surface or a slope and a ledge site.

The effect of solar insolation on the permafrost massif, and, accordingly, its softening, can be enhanced by creating zones of intense heat circulation of rocks in the form of blocks of active climatic effect (hereinafter - AKV blocks).

The proposed method for open pit mining of permafrost zones, including preparing the earth's surface, mining and capital works, mining and preparatory works, overburden and mining operations, quarry processes: preparing rocks for excavation (drilling, loading, blasting), excavation and loading, moving rock (transport of overburden and minerals), and dumping, characterized in that in the process of preparing the next horizon create zones of intense heat circulation in the horns x rocks in the form of blocks of active climatic effects (AKV blocks), by passing workings that serve to create an additional exposed surface of the AKV block.

Moreover, depending on the mining conditions of the field, the blocks are placed along or perpendicular to the direction of development of the mining front.

The proposed technical solution based on the known dependences of the temperature regime in the rock mass of the permafrost zone [5], the relationship of rock strength on temperature [6], has a novelty and inventive step.

The proposed technology has the following advantages compared to the prototype:

- due to the additional free surface, the heat circulation in the rocks of the block is intensified;

- the strength characteristics of the rocks decrease with increasing average temperature of the block, it becomes possible to excavate the rocks of the block without preliminary preparation, or the costs of preparing the rocks for excavation (BB, CB, fuels and lubricants) can be significantly reduced;

- the cost of developing the field is reduced;

- reduced harmful emissions into the atmosphere.

The possibility of implementing this open method of development depends on the mining conditions of the field, the thermomechanical condition of the rocks and their thermophysical properties, parameters of the working area of the quarry and the characteristics of mining equipment.

In FIG. 1 shows a method of open-pit mining of permafrost zones with the creation of zones of intense heat circulation in rocks.

The method is as follows. After preparing the earth's surface, mining and capital works and mining and preparatory work, overburden and mining operations, preparation of rocks for excavation (drilling, loading, blasting), excavation and loading operations, rock movement (transport of overburden and mineral resources) and dumping. In the process of preparing the next horizon, zones of intense heat circulation in the rocks are created in the form of blocks of active climatic impact (AKV blocks), by passing workings that serve to create an additional exposed surface of the AKV block.

Moreover, depending on the mining conditions of the field, the blocks are placed along or perpendicular to the direction of development of the mining front.

The parameters of the blocks, the time of their development is determined taking into account the temperature and climatic characteristics of the area of work, the thermophysical properties of the rocks, the characteristics of the mining equipment in conjunction with the degree of softening of the rock mass in the block.

So, for example, for the conditions of one of the deposits in the central region of the Republic of Sakha (Yakutia), the temperature distribution to a depth of 10 meters in the massif, even without taking into account the additional free surface, is as follows.

This shows that the average temperature in the massif to a depth of 10 meters from April to September changed from -4.45 to + 2.13 ° С. The data obtained indicate that the process of softening the rocks in the AKV blocks will be even more intensive and will reduce the strength of the rocks not only by layer-by-layer soil removal, but also by using the additional exposed surface of the AKV blocks. This will allow excavation of the rock not by the bulldozer method with significant fuel and lubricant expenses and other expenses, but by the excavator-dump truck complex in a short period of time.

Information sources

1. V.V. Rzhevsky. Open pit mining processes. - M .: Nedra, 1978.- 542 p.

2. Yu.I. Anistratov. Technology of open mining: Textbook. manual for universities. - M .: Nedra, 1984. - 287 p.

3. N.N. Rogatin. Technology and mechanization of open cast mining. M., Nedra, 1982.- 277 p.

4. Designing quarries: Textbook / K.N. Trubetskoy, G.L. Krasnyansky, V.V. Chronin, B.C. Kovalenko. - 3rd ed., Revised. - 2009. M.: Higher. school - 694 s.

5. General permafrost (geocryology), ed. 2, revised and supplemented. Textbook. Ed. V.A. Kudryavtseva - M.: Publishing House of Moscow State University, 1978.- 464 p.

6. A.N. Zelenin. Fundamentals of soil destruction by mechanical means, ed. 2, revised and supplemented. M .: Publishing House Engineering, 1968, 375 p.

Claims (1)

The method of open-pit mining of permafrost zones, including preparing the earth's surface, mining and capital works, mining and preparatory work, overburden and mining operations, quarry processes: preparing rocks for excavation (drilling, loading, blasting), excavation and loading, mining rocks (transport of overburden and mineral overburden) and dump formation, characterized in that during the preparation of the next horizon create zones of intense heat circulation in the rocks in the e active climate impact block (AKB) passing through openings, which serve to create additional AKB exposed surface, wherein depending on the mining conditions deposit unit blocks arranged along or transversely to the direction of mining operations front.

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