Volume 04 Issue 04-2022
6
The American Journal of Engineering and Technology
(ISSN
–
2689-0984)
VOLUME
04
I
SSUE
04
Pages:
6-16
SJIF
I
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FACTOR
(2020:
5.
32
)
(2021:
5.
705
)
(2022:
6.
456
)
OCLC
–
1121105677
METADATA
IF
–
7.856
Publisher:
The USA Journals
ABSTRACT
Studies have been carried out to determine the optimal bench height, recommendations have been made to improve
the completeness of extraction of gold-bearing ore and recommended excavation and loading equipment for small-
scale deposits. The change in the values of losses and impoverishment of the ore, as well as the gold content in the
ore, depending on the height of the ledge for various thicknesses of ore bodies, has been established.
KEYWORDS
Berm, understep, ore losses, dilution, ore div thickness, ore reserves, gold content in ore, extraction efficiency,
excavator, front loader.
Research Article
SUBSTANTIATION OF RATIONAL METHODS OF EXCHANGE AND
LOADING WORKS DURING THE MINING OF RESERVES OF SMALL-
SCALE GOLD DEPOSITS
Submission Date:
April 05, 2022,
Accepted Date:
April 15, 2022,
Published Date:
April 28, 2022 |
Crossref doi:
https://doi.org/10.37547/tajet/Volume04Issue04-02
Jabbarov O.I.
Republic Of Uzbekistan, Navoi Region, Navoi, G`alaba shox, Uzbekistan
Kurolov A.A.
Republic Of Uzbekistan, Navoi Region, Navoi, Uzbekistan
Tukhtashev A.B.
Republic Of Uzbekistan, Navoi Region, Navoi, Tolstoy, Uzbekistan
Rakhmatova D.R.
Republic Of Uzbekistan, Navoi Region, Navoi, Pushkin, Uzbekistan
Khamroyeva M.O.
Republic Of Uzbekistan, Navoi Region, Navoi, Chonchorboq, Uzbekistan
Journal
Website:
https://theamericanjou
rnals.com/index.php/ta
jet
Copyright:
Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
Volume 04 Issue 04-2022
7
The American Journal of Engineering and Technology
(ISSN
–
2689-0984)
VOLUME
04
I
SSUE
04
Pages:
6-16
SJIF
I
MPACT
FACTOR
(2020:
5.
32
)
(2021:
5.
705
)
(2022:
6.
456
)
OCLC
–
1121105677
METADATA
IF
–
7.856
Publisher:
The USA Journals
INTRODUCTION
When developing gold deposits using traditional
methods, a bench height of 10-15 m is the most
commonly used in mining practice, while economically
justified values of losses and impoverishment are
achieved, as well as the gold content in the mined ore.
When using this development system, a sufficiently
high productivity of mining and transport equipment is
ensured. And when developing small-scale deposits,
the situation will change radically. When working off
low-power ore bodies, the metal content in ore mined
with a traditional ledge height of 5-10 m may be so low
that ore processing will not be profitable, and it will
accordingly be taken to the dump of off-balance ores
or waste rocks. In such cases, it is necessary to consider
the possibility of excavation of ores and rocks with the
introduction of appropriate changes in the parameters
of the development system, or rather in the height of
the ledge.
High values of losses affect an increase in the share of
redeemable fixed assets in the costs of mining, and
dilution of ore affects its value, metal recovery rates
during enrichment and, ultimately, the cost of final
products.
One of the most important ways to increase the
efficiency of subsurface use in the development of
small-scale deposits is to reduce economically
unjustified losses and dilution of ore during extraction.
MATERIALS AND METHODS
One of the main elements of the development system
is a ledge. The height of the ledge, in turn, is an
important parameter that affects the qualitative and
quantitative indicators of mineral extraction.
In the practice of designing, building and operating
quarries, it is always necessary to determine the height
of the ledges in accordance with specific mining and
geological conditions, mining capabilities and a
number of other factors that require consideration to
determine this important parameter.
When designing , such factors should include:
The size of the mineral productivity and the
duration of a stable period at this level: deadlines
for achieving the selected or specified productivity
with minimum construction time and volumes of
mining and capital works;
The calendar distribution of the volume of work on
the rock mass is the most advantageous for this
productivity;
Minimum costs for the sum of the main processes
for the excavation of 1 m3 of rock mass;
technological equipment that meets these
conditions and productivity;
The grade and quality of the extracted mineral, and
so on.
In other words, the entire main range of issues related
to the design of the quarry must be solved in
conjunction with the determination of the optimal
height of the ledge.
The problem of optimizing the parameters and designs
of the sides of quarries is inextricably linked with the
possibility of radically reducing the costs of operating
the field as a whole, by reducing the volume of
stripping operations, or increasing the share of mining
the reserves of the field in an efficient open method,
with an economically feasible stripping coefficient.
Currently, the existing regulatory documents and
accepted methods for assessing the stability of the
slopes of ledges and sides of quarries are based mainly
on the provisions of soil mechanics and at one time
Volume 04 Issue 04-2022
8
The American Journal of Engineering and Technology
(ISSN
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2689-0984)
VOLUME
04
I
SSUE
04
Pages:
6-16
SJIF
I
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FACTOR
(2020:
5.
32
)
(2021:
5.
705
)
(2022:
6.
456
)
OCLC
–
1121105677
METADATA
IF
–
7.856
Publisher:
The USA Journals
were developed mainly for relatively shallow quarries
in the conditions of massifs represented by loose or
fragile sedimentary rocks.
The spread of these methods to rocks is accompanied
by an excessive margin in the calculations of the design
of the sides and ledges. Instructions for choosing the
height of the ledge are not given either in the norms or
in the methods of technological design of quarries. As
a result of the analysis of past studies, the existence of
two directions in the study of the height of the ledge
was revealed: the first is based on the accounting of
technical indicators, the second is based on the
method of technical and economic analysis. The height
of the ledge is determined and is usually assigned to be
constant for the entire period of mining the quarry. It
is more correct to assume that the height of the ledges
should correspond to the conditions of the quarry
development in each of its periods of operation.
When developing small-scale gold deposits, electric
and hydraulic excavators of direct and reverse ladles of
small volumes, as well as front loaders, are used as the
main excavation and loading equipment for stripping
and mining operations. Currently, there is a new, more
productive and functional mining equipment, for
which there is no feasibility study of the height of the
ledges.
According to the provisions ingrained in the science
and practice of open-pit mining, the complex of basic
mining and transport equipment should ensure
systematic, in accordance with the capacity of the
cargo flow, preparation of rocks for excavation, their
excavation and loading, movement, storage within
each technological zone of the quarry in which the
cargo flow is formed. When choosing the means of
excavation and transport, the following basic
requirements for equipment complexes should be
followed:
1.
The complex of equipment should include only
machines
whose
passport
characteristics
correspond to the mining and technological
characteristics of rocks during each process.
2.
The complex of equipment must comply with the
accepted systems of development and opening,
the size and shape of the quarry, its capacity,
construction and operation period, organizational
conditions of mining operations.
3.
The smaller the number of operating machines and
mechanisms included in the complex, the more
reliable, productive and economical its operation.
4.
Individual machines and mechanisms of the
complex in their parameters must correspond to
each other, be standard and serial, so that they can
be replaced.
In addition, the remoteness of deposits from
engineering infrastructure, limited ore reserves and
small capacities of ore bodies, which characterize the
features of mining small-scale gold deposits, it seems,
should also be taken into account when choosing
excavation and loading equipment. Based on this, the
following additional requirements are imposed on
equipment and technology:
The equipment must be mobile, not requiring the
construction of separate access roads;
There
is
no
need
to
lay
engineering
communications (power lines, industrial water
lines, gas pipelines, etc.);
The possibility of using transport equipment in
combination with other loading equipment (for
example, the use of front loaders at the quarry);
To ensure maximum extraction of ore while
preserving its natural quality.
In modern regulatory sources, there are practically no
methodological provisions and recommendations for
Volume 04 Issue 04-2022
9
The American Journal of Engineering and Technology
(ISSN
–
2689-0984)
VOLUME
04
I
SSUE
04
Pages:
6-16
SJIF
I
MPACT
FACTOR
(2020:
5.
32
)
(2021:
5.
705
)
(2022:
6.
456
)
OCLC
–
1121105677
METADATA
IF
–
7.856
Publisher:
The USA Journals
choosing the height of the ledge and the dredging and
loading equipment for the development of low-power
ore bodies of small-scale deposits. In many small-scale
deposits with approximately the same mining and
geological and mining technical conditions, losses
differ by 2-3 times, and, conversely, in deposits with
unequal mining and geological conditions and different
ore values, they are practically the same. One of the
reasons for this situation is the application of the same
parameters of the mining system and the height of the
ledge without taking into account the specific
conditions of the occurrence of ore bodies, their
structure and the ratio of the value of the extracted
mineral to the costs of mining and processing of ore. In
our opinion, optimal indicators of losses and dilution of
ore, maximum preservation of the initial metal content
in the extracted ore are achieved by reducing the
height of the mining ledge when mining ore bodies of
low power.
The determination of the optimal height of the mining
ledge is proposed to be determined by the proposed
graphoanalytic model developed in the Microsoft
Office Excel program. A schematic diagram for
determining the losses and dilution of ore in the
contact zones and a schematic diagram for an ore div
with a capacity of 6 m, when mining an ore block with
a 5 m high ledge, as well as two 2.5 m sub-steps is
shown in Fig. 1.
In this paper, the values of losses and dilution of ore
are investigated on the basis of the above
methodology for ore bodies with a capacity of 2, 4 m
and 8 m without changing the balance reserves of ore
and metal. At the same time, the height of the ledge
varies in the range: 6, 5, 4, 3, 2,5 m and 2 m .
The developed model makes it possible to
simultaneously determine the values of losses and
dilution in the contact zones, both for the ledge and for
the approach. The basis for the implementation of all
the above calculated data is the methodology for
determining the indicators of losses and dilution for
the conditions of small-scale gold deposits, developed
by associate professor A.B. Tukhtashev and O.I.
Zhabborov, coordinated with the regional inspectorate
for the control of mining and geological activities
"Samarkand-Bukhara" of the State Committee of the
Republic of Uzbekistan for Geology and Mineral
Resources.
Volume 04 Issue 04-2022
10
The American Journal of Engineering and Technology
(ISSN
–
2689-0984)
VOLUME
04
I
SSUE
04
Pages:
6-16
SJIF
I
MPACT
FACTOR
(2020:
5.
32
)
(2021:
5.
705
)
(2022:
6.
456
)
OCLC
–
1121105677
METADATA
IF
–
7.856
Publisher:
The USA Journals
Fig. 1. Schematic diagram of the determination of losses and dilution of ore.
In the calculations, the parameters of loss and dilution
are determined depending on the influencing factors in
the form of a function:
К
п
(К
р
)=f (Э, h
у
, m, α, β, Δ)
(1)
where Э – passport characteristics of the excavator;
h
у
– berm height, m;
m – average ore div capacity, m;
α – angle of incidence of ore bodies, degrees;
β – angle of slope of the excavator face, deg.;
Δ – grip power, m.
To simplify the task , the following initial
parameters are conditionally accepted in the
calculations:
1.
Ore density ρ = 2,6
т/m³
;
2.
The angle of incidence of the ore div α = 75°;
3.
The height of the ledge
h
у
= 6 m (а также 5, 4, 3, 2,5
и 2
m
);
4.
The angle of incidence of the slope of the
excavator face (conditional) β = 50°;
5.
Ore div capacity m = 2, 4
m
и 8
m
;
6.
Ore reserves, B= 2 500 thousand tons;
7.
Metal reserves, М
геол
= 4 000
kg
;
8.
Average metal content in ore С = 1,6
g/t
.
Volume 04 Issue 04-2022
11
The American Journal of Engineering and Technology
(ISSN
–
2689-0984)
VOLUME
04
I
SSUE
04
Pages:
6-16
SJIF
I
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FACTOR
(2020:
5.
32
)
(2021:
5.
705
)
(2022:
6.
456
)
OCLC
–
1121105677
METADATA
IF
–
7.856
Publisher:
The USA Journals
а
б
Fig. 2. Schematic comparison of the areas of losses and dilution of ore at the height of the mining
ledge of 5 m (a) and 2.5 m (b) at the capacity of the ore div of 4 m
According to the above initial parameters, using the
proposed model, a calculation was performed for each
considered ledge height and graphoanalytical data
were obtained at the ore div thickness of 2, 4 m and
8 m.
Figure 2 shows a schematic comparison of the areas of
losses and dilution of ore at the height of the mining
ledge of 5 m and 2.5 m with the capacity of the ore
div of 4 m.
As can be seen from the above, with a decrease in the
height of the ledge from 5 m to 2.5 m, the areas of
losses and dilution decrease, which eventually form the
basis of the values of losses and dilution.
THE MAIN PART
In order to justify the choice of a rational type of
excavation and loading equipment for mining small-
scale gold deposits, calculations and comparison of the
performance of a single-bucket hydraulic excavator
and a front loader with different indicators of the
height of the ledge were made (Table 1)
Volume 04 Issue 04-2022
12
The American Journal of Engineering and Technology
(ISSN
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2689-0984)
VOLUME
04
I
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04
Pages:
6-16
SJIF
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FACTOR
(2020:
5.
32
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5.
705
)
(2022:
6.
456
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OCLC
–
1121105677
METADATA
IF
–
7.856
Publisher:
The USA Journals
Table 1
Comparison of the performance of a hydraulic excavator and a front loader with a bucket volume of 6 m
3
when changing the height of the ledge
№
Name
Ledge height, m
10
9
8
7
6
5
4
3
2,5
2
1.
Annual performance of the
excavator gidravlic excavator Vк =
6m³, thousand m³/year
1 533 1 497 1 453 1 401 1 337 1 257 1 153 1 013
924
816
2.
Annual performance of the front
loader с Vк = 6m³, thousand
m³/year
1 351 1 326 1 298 1 267 1 230 1 188 1 137 1 071 1 031
982
Based on the calculated data obtained, the dependence of the annual productivity of a hydraulic excavator
and a front loader with a bucket volume of 6 m3 in various operating conditions with a change in the height of the
ledge from 2 to 10 m is constructed (Fig. 3).
Fig.3. Change in the performance of a hydraulic excavator and a front loader with a bucket volume of 6
m3 when changing the height of the ledge from 2 m to 10 m
800
900
1,000
1,100
1,200
1,300
1,400
1,500
1,600
2
2.5
3
4
5
6
7
8
9
10
Annual performance of the excavator gidravlic excavator Vк = 6m³, thousand m³/year
Annual performance of the front loader с Vк = 6m³, thousand m³/year
Volume 04 Issue 04-2022
13
The American Journal of Engineering and Technology
(ISSN
–
2689-0984)
VOLUME
04
I
SSUE
04
Pages:
6-16
SJIF
I
MPACT
FACTOR
(2020:
5.
32
)
(2021:
5.
705
)
(2022:
6.
456
)
OCLC
–
1121105677
METADATA
IF
–
7.856
Publisher:
The USA Journals
RESEARCH RESULTS
After performing calculations according to the
developed algorithm, we obtain the corresponding
values of losses, dilution and operational parameters
of the ore for the conditionally accepted initial
parameters, which are given in Tables 2, 3 and 4.
Table 2
Calculated indicators of ore loss and dilution at the ore div capacity, m=2 m
Ledge
height, m
Involved geological reserves
Losses,
П,
%
Dilution,
Р,
%
Operational stocks
Ore reserves,
thousand tons
Average.
content, g/t
Metal,
kg
Ore reserves,
thousand tons
Average.
content, g/t
Metal,
kg
6,0
2 500,0
1,6
4 000,0
18,80
48,60
3 949,42
0,82
3 248,0
5,0
15,60
43,10
3 708,26
0,91
3 376,0
4,0
12,50
36,90
3 466,72
1,01
3 500,0
3,0
9,50
29,60
3 213,78
1,13
3 620,0
2,5
7,90
25,60
3 094,76
1,19
3 684,0
2,0
6,30
21,30
2 976,49
1,26
3 748,0
Table 3
Calculated indicators of ore losses and dilution at the thickness of the ore div, m = 4 m
Ledge
height, m
Involved geological reserves
Losses,
П, %
Dilution,
Р, %
Operational stocks
Ore reserves,
thousand tons
Average.
content, g/t
Metal,
kg
Ore reserves,
thousand tons
Average.
content, g/t
Metal,
kg
6,0
2 500.0
1,6
4 000,0
9,40
29,70
3 221,91
1,12
3 624,0
5,0
7,80
25,80
3 106,47
1,19
3 688,0
4,0
6,30
21,40
2 980,28
1,26
3 748,0
3,0
4,80
16,70
2 857,14
1,33
3 808,0
2,5
4,00
14,20
2 797,20
1,37
3 840,0
2,0
3,20
11,60
2 737,56
1,41
3 872,0
Table 4
Calculated indicators of ore loss and dilution at the ore div capacity, m=8 m
Ledge
height, m
Involved geological reserves
Losses,
П, %
Dilution,
Р, %
Operational stocks
Ore reserves,
thousand tons
Average.
content, g/t
Metal,
kg
Ore reserves,
thousand tons
Average.
content, g/t
Metal,
kg
6,0
2 500,0
1,6
4 000,0
4,70
16,80
2 863,58
1,33
3 812,0
5,0
3,90
14,30
2 803,38
1,37
3 844,0
4,0
3,10
11,70
2 743,49
1,41
3 876,0
3,0
2,40
8,90
2 678,38
1,46
3 904,0
2,5
2,00
7,50
2 648,65
1,48
3 920,0
2,0
1,60
6,10
2 619,81
1,50
3 936,0
On the basis of the calculated data obtained, the dependence of the change in the indicators of loss and
dilution of ore at the thickness of the ore div m = 2 m, m = 4 m and m = 8 m is constructed (Fig.4).
Volume 04 Issue 04-2022
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VOLUME
04
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Pages:
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(2020:
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5.
705
)
(2022:
6.
456
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OCLC
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–
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Publisher:
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Fig.4. The change in the indicators of loss and dilution of ore depending on the height of the ledge at the
thickness of the ore div m = 2 m, m = 4 m and m = 8 m.
As can be seen from Tables 2, 3 and 4, as well as Fig. 4,
with a decrease in the height of the mining ledge, the
following positive results are achieved:
1.
The reduction of ore loss values is achieved by
almost three times.
1
4
7
10
13
16
19
22
25
28
31
5
10
15
20
25
30
35
40
45
50
55
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
Or
e
lo
ss
es,
%
Dilu
tio
n
o
f
o
re,
%
Ledge height, m
Dilution of ore at m =2 m, %
Dilution of ore at m =4 m, %
Dilution of ore at m =8 m, %
Ore losses at m =2 m, %
Ore losses at m =4 m, %
Ore losses at m =8 m, %
Volume 04 Issue 04-2022
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VOLUME
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Pages:
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(2020:
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)
(2022:
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–
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2.
With the traditional method of mining an ore div
with a capacity of m = 2 m, the height of the mining
ledge hu = 5.0 m, the production metal is obtained
Me = 3,376.0 kg, with an average metal content in
the ore – 0.91 g / t, and with a height of the ledge
hu = 2.0 m, it is Me = 3,748.0 kg of metal with an
average metal content in the ore 1.26 g/t thereby
the ore becomes profitable for processing at
hydrometallurgical plants with an onboard content
of 1 g/t and below or at heap leaching sites.
3.
The decrease in the volume of processed ore is
731.77 thousand tons, an increase in the amount of
extracted gold by 372 kg.
Reducing the height of the ledge has not only positive
indicators, but also some disadvantages:
1.
Reduced productivity of the mining and transport
complex involved on the thoracic ledge.
2.
The volume of auxiliary work on the sinking of split
trenches will slightly increase and the rate of
deepening of the quarry will decrease.
3.
Reducing the height of the ledge to 2.5-3.0 m and
below requires the use of special excavation and
loading equipment, or changing the technological
schemes of mining ore blocks.
4.
On the basis of the calculated data obtained, the
dependence of the annual productivity of a
hydraulic excavator and a front loader with a
bucket volume of 6 m3 is constructed. It is
recommended to use front loaders in the
conditions of working off ledges (approaches) at a
height below 4 m.
CONCLUSION
Based on the work carried out, the following
conclusions were made:
1.
The choice of a rational ledge height for the
development of small-scale gold deposits is of
current scientific and practical importance for the
mining industry and requires further detailed
study.
2.
To reduce losses and impoverishment at the stages
of pre-project and design work for each small-scale
deposit, it is necessary to choose the optimal
height of the mining ledge depending on the
thickness of the ore div and the metal content in
the ore, and also consider options for selective
mining of ore bodies of small thickness with the
introduction corresponding changes in bench
height and consider various options for the level of
completeness of extraction of ore reserves with
the introduction of appropriate changes in bench
height.
3.
The excavation and loading equipment must be
selected depending on the height of the ledge,
respectively, the elements and parameters of the
development system must be determined
depending on the parameters of the mining and
transport equipment.
4.
For mining ore bodies with a thickness of 2 m, the
height of the mining bench should be 2 m, with a
thickness of ore bodies of 4 m, respectively, 3 m,
with a thickness of ore bodies of 8 m, the height of
the mining bench should be 5 m.
5.
From Table. It follows from Table 1 that with a
ledge height of 2 m and a gold grade in geological
reserves of 1.6 g/t, the content in the mined ore is
1.26 g/t, while the ore becomes profitable for
further processing at the hydrometallurgical plant
GMZ-2 of the Navoi MMC or in the heap leaching
area.
6.
The excavation and loading equipment must be
selected depending on the height of the ledge,
respectively, the elements and parameters of the
development system must be determined
Volume 04 Issue 04-2022
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VOLUME
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Pages:
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(2020:
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32
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)
(2022:
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IF
–
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Publisher:
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depending on the parameters of the mining and
transport equipment.
7.
For the development of ore bodies of low
thickness, it is advisable to reduce the height of the
mining ledge from 2 to 4 m; it is recommended to
develop such an excavation unit with a front
loader.
8.
When mining ledges with a height of 4 m and
above, the generally accepted technology of
excavation and loading operations with hydraulic
excavators seems to be optimal.
REFERENCES
1.
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