RU2294433C1 - Method for closely located ore bodies cutting with separate pits - Google Patents

Abstract

FIELD: mining, particularly opencast mineral mining.

SUBSTANCE: method involves stepping rock up to design outline with leading in the first stage pit edge; transporting ore along main decline to plant and stacking overburden in dump; excavating connection entry between the first stage pit and the second stage pit so that the entry is opened in previously excavated the first stage pit; cutting the second stage pit; transporting ore and overburden from the second order pit via connection entry; depositing overburden from the second order pit in the first stage pit goaf after termination of the first stage pit excavation. Before ore and overburden transportation from second order pit via connection entry overburden excavated from the second order pit is accumulated in outer dump. Overburden from the second order pit is conveyed to day surface along temporary decline system. When the second pit side reaches designed outermost outline temporary declines are killed.

EFFECT: reduced costs of deposit development and decreased hazardous action of mining operations on environment.

4 cl, 4 dwg, 2 tbl, 2 ex

Description

The invention relates to the mining industry and can be used in open pit mining of mineral deposits, namely, open pit mining of kimberlite pipes in deep quarries.

There is a method of open-pit mining of deposits (Pat. 2124128, MKI E 21 C 41/26, 02/07/1997, publ. 12/27/1998 Bull. No. 36), including the development of associated minerals with the formation of at least one leading quarry, opening and preparation the main mineral deposit with the delivery and placement of overburden in the developed space of the advanced quarry.

The disadvantages of this method is that raising the overburden to the level of the day surface for their delivery to the leading quarry leads to overrun and narrows the scope of the method; storage of the entire volume of overburden from the main quarry to the leading one leads to a transport overrun, for example, when transporting rock mass from the flanks of the main deposit remote from the quarry, which causes an increase in material costs for developing the field.

There is also a known method of developing steeply dipping deposits when mining deep pit horizons, including pit mining by bursts, preparing rock mass using a blasting method, dumping overburden into external and internal dumps, in which pit mining is advanced ahead of the first stage contours with the formation of a spiral exit and at the same time produce opening and layer-by-layer development of the second stage section, overburden of the first and second stage is moved to an external dump, on the second stage section they loop the exit system, and as the mining operations decrease after opening the mineral in the second stage, the second stage work platforms are connected to the spiral first stage congress by temporary exits, and after the first stage has been worked out, the second stage overburden is moved to the worked out space of the first stage (Pat. No. 2187648 , IPC E 21 C 41/26, 2001, published on 08.20.2002 Bull. No. 23).

The disadvantages of this method are: the use of a loop form of the route in the second stage, leading to a decrease in the angle of the open side of the quarry, as well as a decrease in the speed of movement of the vehicle; an increase in the recoil shoulder caused by the need to transport overburden from the horizons of the second stage to the upper horizons of the dump; limiting the use of dump truck carrying capacity for overburden transportation to lower horizons; the limitation of the use of the method on small areas, caused by the small capacity of the internal dumps.

The closest in technical essence and the achieved result is a method of open development of steeply dipping mineral deposits (AS No. 1121434 MKI E 21 C 41/00, 08/12/1983, publ. 10/30/1984 Bull. No. 40), including sequential mining of adjacent quarries with parallel approaches, transportation and dumping of overburden into a dump, dumping of overburden into an exhausted quarry, connecting work in the jumper between adjacent quarries from the quarry being mined to spent, and the connecting mine in in the form of a cutting trench in the lintel, it is diagonally drawn from one of the ends of the quarry to the opposite end of the quarry with access to the latter, the railway is laid, the adjacent side of the quarry is worked out with the re-mining of dumped overburden, from which transport platforms for railway track.

The disadvantages of this method are: conducting a connecting split trench diagonally from one of the ends of the quarry to the opposite end of the spent, which leads to an increase in the distance of transportation of rock mass; limited in depth use of connective workings in the form of a trench, which reduces the effectiveness of the method; the complexity and cost of developing deposits when using railway transport to develop deep quarries; the limited application of the method by quarries located in the immediate vicinity (the spent quarry is fully or partially located in the mine circuit).

All this makes the known method insufficiently effective in terms of economic performance of a quarry.

The technical result of the invention is to increase the efficiency of the method of mining a deposit by reducing the cost of transporting overburden to dumps.

The specified technical result is achieved by the fact that in the known method of mining two nearby ore bodies in separate quarries, including mining of rocks with ledges to the design contour ahead of the first stage quarry contours, transporting ore to the factory by capital exit and dumping overburden to the dump, sinking between quarries of the first and second stage of the connecting mine with access to the board of the initially worked quarry of the first stage, development of the quarry of the second stage, protractor ore and overburden from the second stage quarry through the connecting hole, placement after completion of the first quarry overburden mining, placement of the second stage quarry in the developed space of the first stage quarry, and before the transportation of ore and overburden from the second stage quarry through the overburden opencast mining of the second stage are stored in an external dump, their delivery to the surface is carried out according to a system of temporary exits, and when the side reaches the second stage limit circuit system of temporary congresses extinguished.

The development of the second stage quarry begins when the first stage in the quarry reaches the current depth of mining, at which the completion time of the first stage quarry will be equal to the opening and preparation time of the second stage quarry.

The penetration of the connecting excavation is carried out after selecting its type on the basis of a preliminary calculation of the critical depth of the external trench.

In the presence of a buried placer lying between ore bodies, a connecting mine runs along the bottom of the buried placer.

In the proposed method, new features in comparison with the prototype are the following:

Before the transportation of ore and overburden from the second stage quarry through the connecting mine, the overburden of the second stage quarry is stored in a temporary or permanent external dump, they are delivered to the surface using a system of temporary ramps, when the side ramp of the second stage of the limiting contour is extinguished, which allows simultaneous mining of two quarries while reducing the cost of delivering overburden to a temporary dump on the surface by minimizing tion conveying distance;

development of the second stage quarry begins when the first stage in the quarry reaches the current depth of mining, at which the completion time of the first stage quarry will be equal to the opening and preparation time of the second stage quarry, which ensures a continuous process of mining and thus increases the efficiency of mining two closely located ore bodies for expense reduction of material costs;

sinking of the connecting working out is done after selecting its type on the basis of preliminary calculation of the critical depth of the external trench, so the connecting working out takes place in the form of either a trench or a tunnel at the optimal depth with minimal material costs, which makes the method effective;

connecting excavation takes place on the sole of buried placers, lying between ore bodies, which minimizes the cost of penetration of the connecting excavation due to its placement in the worked out space of the buried placer.

The method is illustrated in figures 1, 2, 1a, 2a.

Figure 1 shows a schematic diagram of the quarries of the first and second stage K1 and K2 and the dump when implementing the method of mining two nearby ore bodies by separate quarries.

Figure 2 shows a schematic diagram of the mining of two ore bodies with a penetration of the connecting excavation at the bottom of the buried placer,

Where:

K1 - quarry of the first stage;

K2 - quarry of the second stage;

1 - the first ore body;

2 - the second ore body;

3 - design contour of the first stage quarry;

4 - external dump quarry of the first stage;

5 - sub-quarry reserves;

6 - connective development;

7 - a temporary congress in the career of the second stage;

8 - the ultimate contour of the quarry of the second stage;

9 - capital congress of the first stage quarry;

10 - internal dump in the career of the first stage.

11 - buried placer;

12 - external dump quarry of the second stage;

13 - artificial pillar at the bottom of the first stage quarry.

The method is as follows.

When mining two nearby ore bodies 1 and 2 (Fig. 1), the quarry is first worked out, which is located closer to the mineral receiving point. The first stage quarry K1 is mined according to traditional technology, including mining of rocks and ore mining with ledges to the project circuit 3, preparation of the rock mass for excavation, formation of non-working ledges at the boundary of the final contour, capital exit 9, transportation of overburden to external dumps 4, and ore to the processing plant (PF). The preparation of the rock mass for excavation is carried out by the blasting method, the transportation of the rock mass by dump trucks. According to the capital exit 9, ore is transported to the processing plant, and overburden to external dump 4. After mining the quarry of the first stage K1 to the final circuit there, if necessary, work is carried out to ensure the completeness of underground mining of quarry reserves of 5 minerals. During the finalization of the quarry of the first stage of K1, work is being done on sinking of the connecting production 6, as well as the beginning of overburden and mining operations at the quarry of the second stage of K2. The rock mass extracted during these operations is delivered to the surface by a system of temporary exits 7, which, when the side of the open pit K2 reaches the limit circuit 8, are extinguished. After completion of work in the quarry of the first stage K1 and redemption of temporary exits 7 in the quarry of the second stage K2, freight transport communication between the quarry of the second stage K2 and the day surface is carried out only through connecting excavation 6 and the capital exit 9 of the quarry of the first stage K1, while overburden delivered by connecting the development of 6 aboard the K1 first stage quarry, is dumped into the internal dump 10 to the lower horizons of the K1 first stage quarry, and ore is delivered to the surface by the capital exit 9 of the first quarry K1 th queue.

When developing a buried placer 11, lying between two ore bodies 1 and 2, the connecting excavation 6 from the quarry of the first stage K1 to the quarry of the second stage K2 pass along the bottom of the buried placer 11, placing it in the worked out space of the worked placer 11.

An example of a specific implementation of method 1.

In order to fully disclose the technical essence and advantages of the present invention with respect to kimberlite pipes, an example is given where the initial data are taken as follows: the distance between the centers of kimberlite pipes 1 and 2 is 2.1 km (Fig. 1). It is supposed to conduct the pipe mining in an open way in separate quarries: pipe 1 with a quarry of the first stage K1, pipe 2 with a quarry of the second stage K2.

At the stage of quarrying, the order of their development is determined taking into account that the quarry located closer to the processing plant is involved in the priority mining, in this case, the quarry of the first stage K1. Then, the optimal depth of open cast mining is determined and the preliminary contours of the quarries are built at the end of mining, their external dumps are designed.

The depth of open pits for both pipes 1 and 2 was taken equal to 405 m, the volume of overburden in the contour of the open pit of the second stage K2 is 134.8 million m ³ , the area of the external dump 12 of the open pit of the second stage K2 was 2776.6 thousand m ² , its height 65 m, the volume of rocks placed in the dump - 161.8 million m ³ taking into account the coefficient of residual loosening Cr = 1.2. The volume of rock mass in the quarry of the first stage K1 and its external dump do not matter in these calculations, the geometric volume of the quarry of the first stage is 191 million m ³ . When calculating the cost of transportation adopted the cost of transportation equal to 6.1 r / tkm (see table).

Determine the type of connecting development 6 depending on the depth of its laying. The choice of the type of connecting excavation 6 (underground or open) is carried out according to the well-known formula for determining the critical depth of the external trench (1), with which it is advisable to proceed to the underground excavation:

where S _p is the cross section of the underground opening (connecting) mine, S _p = 175 m ² (based on the two-lane traffic conditions of CAT-777 dump trucks);

With _p - the cost of sinking 1 m ³ underground, With _p = 4500 rubles / m ³ ;

With _t - the cost of driving 1 m ³ trenches, With _t = 150 rubles / m ³ ;

α - angle of slope of the sides of the trench, 60 degrees;

b - the width of the base of the trench, 30 m

According to the calculation results, the critical depth of the connecting excavation 6 - open trench turned out to be equal to 73 m, below this depth it is advisable to pass the connecting excavation 6 underground method.

Based on economic efficiency, choose the corrected depth of the laying of the connecting workings 6, in this case equal to 45 m.

After determining the type and depth of the connecting workings 6 make adjustments to the autopsy schemes and the design of the sides of the quarries. The scheme of opening the quarry of the first stage K1 is adjusted in such a way as to ensure the possibility of docking the capital exit 9 of the quarry of the first stage K1 with connecting output 6 (mountains +360 m), and the scheme of the opening of the quarry of the second stage K2 - taking into account the provision of cargo transportation of the lower horizons of the quarry with a daily surface through connecting excavation 6 and capital exit 9 of the first stage quarry K1, that is, without internal capital exits above the horizon of connecting excavation 6 (above a mountain of +360 m). The final diagram of the quarries of the first and second phases of K1 and K2 and the blade is shown in Figure 1.

The implementation of the method begins with mining the first stage K1 quarry using traditional technology, including overburden mining and ore mining with working ledges, blasting the rock, mining the K1 first stage quarry with the formation of capital exit 9, overburden removal into the external dump 4 of the first stage K1, and ore to the processing plant (PF). In the event that at the end of mining of the first stage K1 quarry pit reserves 5 remain, to ensure the possibility of their full underground mining, an artificial pillar 13 is formed at its bottom.

In the period of a significant decrease in the volume of mining in the quarry of the first stage K1, the released mining and transport equipment is transferred to the excavation of the connecting mine 6.

After the quarry K1 reaches the calculated depth H _T = 382.5 m, at which the time T _{1 of} finalizing the quarry of the first stage K1 will be equal to the time T _{2 of} opening and preparing the quarry of the second stage K2, they begin to open and layer-by-layer development of the quarry section of the second stage K2.

Time T ₁ is determined by the expression:

where N _k1 - the final depth of the quarry of the first stage K1,405 m;

N _T - the current depth of the quarry K1, m;

h _d1 - the rate of decrease in mining during the completion of the quarry of the first stage K1, 15 m / year.

Time T ₂ is determined by the expression:

where N _c2 - the depth of mining and capital works on the quarry of the second stage K2, 30 m;

h _c2 - the rate of decrease in mining during the construction of a quarry of the second stage of K2, 20 m / year.

From the equality of T ₁ and T ₂ we find the depth H _t :

The overburden extracted during these operations is stored on the external dump 12. The rocks are delivered to the dump 12 at temporary exits 7, which, after the planned volumes are transported, when the side of the open pit of the second stage K2 reaches the limit circuit 8 are repaid.

Connecting excavation 6 is carried out at a depth of 45 m (mountains. +360 m), the amount of work during the excavation of connecting excavation 6 is 2.8 million m ³ .

After finalizing the quarry of the first stage K1 to the project circuit 3 and carrying out preparatory work in it, if necessary, providing underground mining of quarry reserves 5, mining of the quarry of the second stage K2 is started according to a new scheme using internal dumping in the quarry K1. Overburden is delivered via connecting hole 6 aboard the K1 first stage quarry and then dumped into internal dump 10 onto the lower horizons of the K1 first stage quarry. Ore is also transported through connecting mine 6 to the open pit of the first stage K1, then it is delivered to the surface by a capital exit 9 of the open pit of the first stage K1 and then transported to the processing plant.

Table 1 illustrates the cost-effectiveness of using the new mining method compared with the use of traditional methods with external dumping. The new mining method reduces the average weighted distance of transportation of overburden by 0.42 km (from 2.94 km to 2.52 km), which saves transport costs of 811 million rubles. (at a cost of transportation of 6.1 rubles / tonne).

Also, the use of a new mining method allows to reduce the overburden volume in the open pit circuit of the K2 second stage by 0.4 million m ³ by changing the opening pattern of the upper horizons, which reduces the cost of stripping by 20 million rubles, since the opening of the upper part of the quarry is carried out through connecting production, which excludes the placement of capital exits in the contour of the quarry.

Other positive effects from the introduction of a new mining method (the economic effect of these factors in the calculations were not taken into account) include:

- reduction in the number of dump trucks working inside the quarry, which leads to a decrease in downtime due to gas contamination;

- reduction of the area of external dumps of the K2 second-stage quarry from 2776.6 thousand m ² to 744.2 thousand m ² , which reduces the land acquisition area and improves the environmental situation in the area of the field development;

- internal dumping allows to reduce the cost of reclamation of dumps and career of the first stage K1.

An additional cost in introducing a new technology is the cost of sinking a connecting trench. The volume of these works is 2.8 million m ³ or 420 million rubles. in monetary terms.

In total, from the introduction of a new mining method, the cost savings will amount to 411 million rubles.

Table 1 Weighted average transportation distances, km Volume in
external dump, million tons Volume in
internal dump, million tons Cargo turnover
option, mln.tkm The cost of
transportation, million rubles To an external dump To internal dump exit from the quarry - entry to the dump on a dump climb out of a quarry Total will connect. production on a dump ascent (descent) from the quarry Total Total New technology metrics 0.3 0.4 0.29 0.99 1,1 0.3 1.43 2.83 2,52 52.6 256.6 778 4746 Indicators of traditional technology with external dumping 0.3 0.9 1.74 2.94 - - - - 2.94 310 - 911 5557 Save transportation costs 811

An example of a specific implementation of method 2.

In the case of occurrence between two ore bodies, for example kimberlite pipes, the distance between the centers of which is 2.1 km, of the buried placer, the connecting excavation runs along the bottom of the buried diamondiferous placer 11, the depth of the sand base is 60 m, and their thickness is 20 m.

First of all, the quarry of the first stage K1 is mined and, at the same time, a buried diamond-bearing placer is mined 11. Mining is carried out using preliminary loosening of rocks by an explosion. The blasted rock mass is shipped by excavators and loaders to dump trucks, while the overburden from the first stage quarry K1 is transported to an external overburden dump 4. In case the placer 11 is mined using internal dumping, the sole section along the placer should be left uncovered, the width of which should provide two-way traffic of dump trucks. In the future, this section will serve as a connective development.

Upon reaching the quarry of the first stage K1 with a depth of H _T = 382.5 m, at which the completion time of the quarry of the first stage K1 will be equal to the time of opening and preparation of the quarry of the second stage K2, mining of the quarry of the second stage K2 begins. Depth N _t is determined by the expression:

where N _k1 - the final depth of the quarry of the first stage K1,405 m;

N _s2 - the depth of mining and capital works on the quarry of the second stage K2, 30 m;

h _d1 - the rate of decrease in mining during the completion of the quarry of the first stage K1, 15 m / year;

h _c2 - the rate of decrease in mining during the construction of a quarry of the second stage of K2, 20 m / year.

While mining quarries of the first and second phases K1 and K2, the overburden from the quarry of the second stage K2 is moved through temporary exits 7 to the external overburden dump 12.

After the planned volumes are transported from the open pit of the second stage K2 to the external dumps 12, when the side open pit of the second stage K2 reaches the limit circuit 8, the temporary exits 7 are canceled and the cargo transportation connection of the second stage K2 with the surface is carried out only through connecting ramp 6 and the capital exit 9 of the first stage quarry K1, and overburden from the quarry of the second stage K2 is transported to the mined space quarry of the first stage K1

Comparison of the cost of transportation of overburden by the proposed mining method with the cost of transportation of overburden from K2 quarry to external dumps 12 are shown in table 2.

table 2 Option Transportation direction Volume of transportation, mln tons Weighted average transportation distance, km Cost of transport work, rubles / ton-km Transportation costs million rubles Traditional to external dump 310 2.94 6.1 5560 The proposed method to external dump 52.6 0.99 6.1 318 into quarry quarry I 256.6 2.67 6.1 4179 Total 4497 Cost savings for overburden transportation, million rubles 1063

In addition to reducing the cost of transport work, the use of a new mining method allows to reduce the volume of stripping in the quarry circuit of the K2 second stage quarry by 0.4 million m ³ by changing the opening pattern of the upper horizons, which reduces the cost of stripping by 20 million rubles.

Other positive effects from the introduction of a new mining method (the economic effect of these factors in the calculations were not taken into account) include:

- reduction in the number of dump trucks working inside the quarry, which leads to a decrease in downtime due to gas contamination;

- reduction of the area of external dumps 15 of the K2 second stage quarry from 2776.6 thousand m ² to 744.2 thousand m ² , as well as the area occupied by tailings of the processing plant, which reduces the land acquisition area and improves the environmental situation in the area of the field development;

- internal dumping can reduce the cost of reclamation of dumps and K1 quarry.

Thus, the above information indicates that the claimed method can be used in the mining industry for the mining of two nearby ore bodies in separate quarries. Therefore, the claimed invention meets the condition of "industrial applicability".

Claims (4)

1. A method of mining two closely located ore bodies by separate quarries, including mining of rocks with ledges to the design contour ahead of the first stage quarry in the contours, transportation of ore to the mill by capital exit and dumping of overburden into the dump, sinking between connecting quarries of the first and second stages of connecting production with the departure of the initially mined quarry of the first stage, mining of the quarry of the second stage, transportation of ore and overburden from the quarry of the second stage through connections undercut mining, placement after completion of mining of the first stage quarry of overburden rocks of the second stage quarry in the mined space of the first stage quarry, characterized in that before the transportation of ore and overburden from the second stage quarry through the connecting development, overburden rocks of the second stage quarry are stored in an external dump, their delivery to the surface is carried out according to the system of temporary exits, and when the side of the quarry reaches the second stage of the limit circuit, the system of temporary exits they are. 2. The method according to claim 1, characterized in that the development of the second stage quarry begins when the first stage in the quarry reaches the current depth of mining, at which the completion time of the first stage quarry will be equal to the opening and preparation time of the second stage quarry. 3. The method according to claim 1, characterized in that the penetration of the connecting workings is carried out after selecting its type based on preliminary calculation of the critical depth of the external trench. 4. The method according to claim 1, characterized in that in the presence of a buried alluvial bed lying between ore bodies, the connecting excavation runs along the sole of the buried alluvial.

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