RU2503814C1 - Erection method of protective cushion above developed vertical ore bodies under permafrost zone conditions - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: at the bottom of the developed open pit there created is a freezing circuit by driving of zigzag-shaped trenches and laying of pipes in them; after that, ice rock backfill is erected by freezing-out overburden; a waterproof screen is laid and filled with a clay loam layer. Then, an upper freezing circuit is made of pipes and a heat-insulating layer of local loose materials, a waterproof screen and a clay loam layer is erected on it and covered with overburden. As a protective cushion is being created, cold air is delivered via lower freezing circuit, and cooled air is supplied via upper freezing circuit during warm season.

EFFECT: providing insulation of underground work against penetration of surface water and dynamic actions under permafrost zone conditions; providing safe work performance.

2 dwg

Description

The invention relates to the mining industry and can be used in underground mining of diamond-containing pipes of the North, the upper part of which is worked out in an open way.

There is a method of developing kimberlite pipes, involving the transition from an open to an underground method for further mining of the field, the construction of an artificial concrete pillow at the bottom of the quarry protecting the mine from the penetration of surface water and dynamic effects (from collapsing rocks of the sides of the quarry) [1] (prototype).

The main disadvantages of the concrete pillow and the method of its construction are:

- high labor costs and significant construction cost;

- high consumption of imported cement;

- the complexity of conducting and isolation of concrete work in the rainy period;

- the difficulty of waterproofing the border sections of the pillow adjacent to the sides of the quarry during the summer thawing of rocks;

- the seasonal nature of concrete work (in the short warm season);

- high rigidity of the concrete structure, non-exclusive possibility of cracking under dynamic effects and temperature stresses;

- the complexity and high risk of concrete work in conditions of increased breakability of thawing rocks and water cut bottom of the quarry in the summer.

A method is proposed for erecting a protective cushion over the ore bodies being mined under cryolithozone conditions, including the formation of an artificial protective structure in winter time, characterized in that at the bottom of the spent quarry they create a lower freezing circuit by digging zigzag trenches and laying large diameter pipes in them. After that, an ice-mound embankment is sequentially erected on the circuit by layer-by-layer freezing of overburden, on which an ice layer is frozen to accumulate cold, a waterproofing screen is made of a frost-resistant plastic film, which is covered with a layer of loam to protect against mechanical damage, then, when the design height is reached, the upper freezing structure is formed the circuit is also made of large-diameter pipes, on which they erect: a heat-insulating layer of local bulk materials, waterproofing screen, a layer of loam and covered with overburden, wherein at least create a protective cushion produce injecting cold air freezes the bottom contour, and supplying cooled air to the upper contour Freezing is carried out in the summer.

The required technical result is expected to be obtained with the maximum use of climatic features and natural (natural) resources of the permafrost zone:

- long winter with extremely low temperatures;

- the presence of high-potential atmospheric cold, the reserves of which are inexhaustible.

Important factors are also:

- the presence at the mining enterprise of overburden dumps;

- extensive experience in the construction of ice-related hydraulic structures (dams, dams) in the North.

Introduced in the claims such an essential feature as the use of ice-rock material instead of concrete for the construction of ice-mound allows you to do without the use of imported, expensive cement and labor-intensive and unsafe concrete-laying operations, which allows you to work for a long winter period using well-developed high-performance technologies, used in the construction of rock-fill ice-rock hydraulic structures in cryolite one (dikes, dams).

An essential distinguishing feature is the fact that to accelerate the erection of the pillow and then maintain it in a year-round frozen state, low-energy freezing circuits (upper and lower) are used, where cold atmospheric air is used as a refrigerant in the winter and artificially cooled in the summer.

The next distinguishing feature is that the cheapest material, atmospheric air, is used as a refrigerant in the freezing circuits, thereby reducing the cost of purchasing antifreeze.

An essential feature is the use of ice with a high heat capacity as a cementing material, which allows one to accumulate a large cold reserve in the pillow in the winter period, spent on compensation of external heat influx (atmospheric and mine heat).

Equally important is the fact that all the main work is carried out during a long winter period. At the same time, a high speed of erection of the pillow is also provided, because they use well-developed technology in the North, high-performance equipment and, in addition, a laid layer of frozen overburden, spilled with water, quickly freezes at low winter temperatures outside.

The inventive method is illustrated by two drawings (Figure 1 and Figure 2). Figure 1 presents the plan of the spent quarry with the arrangement of all equipment for the construction of a protective pillow, and figure 2 is a vertical section.

Symbols adopted in the drawings:

1 - bottom of the spent quarry;

2 - zigzag horizontal trenches cut at the bottom of the quarry;

3 - lower freezing circuit;

4 - an erected protective ice-rock embankment;

5 - a forcing fan;

6 - pipeline for supplying cold air;

7 - a freezing layer of ice;

8 - waterproofing screen of frost-resistant plastic film;

9 - a layer of loam;

10 - upper freezing circuit;

11 - a heat-insulating layer of local bulk materials (wood chips, slag);

12 - waterproofing screen of frost-resistant plastic film;

13 - a layer of loam;

14 - overburden layer;

15 - forcing fan;

16 - air supply pipe;

17 and 18 are energy air coolers.

The implementation of the proposed method in practice is as follows. In winter, a network of zigzag horizontal trenches 2 is cut into the bottom of a worked-out, planned, and drained quarry 1 into which large diameter pipes of the lower freezing circuit 3 are laid. Then, a protective ice-bearing embankment 4 is layered using hydraulic engineering technologies [2] by layer-by-layer filling of frozen overburden rocks with their subsequent ramming, spilling with water and freezing with natural cold of each layer. After freezing the first layer, the second layer is erected using the same technology and so on until the estimated height of the embankment is reached. To accelerate the freezing of a single ice-rock layer, a blowing fan 5 is turned on to supply cold atmospheric air through a pipe 6 through the lower freezing circuit 3.

Then, an ice layer 7 is frozen over the erected ice-rock embankment 4, and then a waterproofing screen 8 is laid from a frost-resistant high-strength polyethylene film, which is sprinkled with a protective layer of loam 9. On top of it, large-diameter pipes are laid in a zigzag shape in the horizontal plane, forming the upper freezing circuit 10, which is covered with a heat-insulating loop 10 layer 11 of local bulk materials (slag, wood chips, peat). After that, a waterproofing polyethylene screen 12 is laid, on top of which a layer of loam 13 is poured, and then a layer of overburden is poured 14. During the construction of the mine, air is supplied to the upper freezing circuit by fan 15 through line 16, with preliminary cooling in summer in an energy air cooler 17. The lower freezing circuit 3 operates year-round to compensate for heat inflows coming from an existing mine, using in the winter as a refrigerant ambient air, and in the summer, the injected air is pre-cooled in the energy cooler 18. As a result of this mode of operation of the freezing circuits, a layer-by-layer erected protective cushion accumulates cold, the reserves of which are used to compensate for heat influx from solar radiation in the summer, as well as the heat coming from operating mine, thereby reducing the cost of producing artificial cold.

The main advantages of the proposed method:

- high speed of work;

- low cost of the erected structure due to the use of local materials;

- a small number of technological operations;

- high mechanization of all types of work;

- low costs for the production of artificial cold, due to the use of natural (atmospheric) cold;

- ease of erection and freezing of the embankment with natural cold;

- high waterproofing properties of the pillow due to the presence of three protective barriers: from frozen, waterproof ice rocks and two screens made of plastic film;

- low material costs for the purchase of equipment;

- the duration of the season;

- high cold storage capacity of the erected protective cushion, which allows to accumulate a large supply of cold during the winter period, thereby reducing the cost of producing artificial cold;

- low rigidity and high plasticity of the ice-cushion cushion, damping the dynamic effects of collapsing rocks from the sides of the spent quarry;

- high protection of the pillow from thawing by solar radiation, as well as from the heat coming from the mine being built, and then the existing one, through the use of two freezing circuits and thermal insulation.

- low cost and versatility of the freezing circuits, simple in design and simple to manufacture, which are used both during the construction of the protective cushion, and during the construction of the mine and its subsequent operation.

Information sources

1. RF patent No. 2400625.

2. Biyanov G.F. Soil dams on permafrost - Yakutsk, 1989 .-- 152 p.

Claims (1)

A method of erecting a protective cushion over the mined vertical ore bodies under cryolithozone conditions, including the formation of an artificial protective structure in winter time, characterized in that first, at the bottom of the spent quarry, a lower freezing circuit is created by driving zigzag trenches and laying large diameter pipes in them, and then on an ice-mound embankment is sequentially erected in the circuit by layer-by-layer freezing of overburden, on which an ice layer is frozen to accumulate cold, on they lay a waterproofing screen made of frost-resistant polyethylene film, which is covered with a layer of loam to protect against mechanical damage, then, when the design height is reached, an upper freezing circuit of large diameter pipes is formed, on which a heat-insulating layer of local bulk materials is erected, a waterproofing screen, a loam layer and cover overburden, in this case, as the protective cushion is created, cold air is injected along the lower freezing circuit, and hlazhdennogo air freezes on the upper contour produced in the warm season.

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