Modeling Development of Deep Horizons

8/12/2019 Modeling Development of Deep Horizons

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Modeling Development of Deep Horizons

of Open PitsBelyakov NikolayJ.S.C. INVESTTEK, Moscow, Russia

Abstract. An open-pit deposit block model serves the basis for a performance

analysis of resource-saving technologies used in deep horizons. Indicators of

various technological solutions are determined based on a complex dynamic

system of mining performance evaluation. To determine life cycle limits of

individual engineering solutions in modeling an open-pit mine development, a

criterion is needed to characterize the remaining life cycle of the facility under

consideration at any given moment in time.

It is appropriate to use the Current Net Present Value (CNPV) as such a

criterion with all the points of time schedule serving consistently as reduction

factors in the calculation. On the left side of the chart, the reduction range is

limited to the current point, while on the right side - by the margins of the range

under consideration.

At deep pit levels, electric lifts, equipment based on mechanical disruption of

hard rock and technologies that enable the development of mineral resources

without overburden disposal, are considered as resource-saving technologies. The

study established the effective applications of technology solutions for developingdeep levels of quarries. The findings allow for reducing environmental damage

from open pit mining as well as for increasing the economic effect. A conveyor

design has been proposed, complying to the maximum extent possible with the

following requirements imposed by technological processes used at deep pit

horizons: a minimum material and energy consumption, a short assembly and

disassembly period, a confined arrangement surface area, a minimum limitation of

transport communications for wheeled traffic.

Keywords: open pit mining, Current Net Present Value, resource-saving

technologies, reducing environmental damage, suspended cable-belt conveyor.

1 IntroductionWith the increased depth of open-pit mines, the costs of transportation become the

key factor in determining the overall mineral deposit effective development costs

and affect the main technical and economic indicators of production. Despite thegreat experience accumulated in deep open-pit mines' development and a

significant amount of research in that area, further process improvement and

technological advancement remain extremely relevant. The aim of the research is44 B. Nikolay

to substantiate the best-performing options in the use of resource saving

technologies, formalize processes and technology characterization requirements

for deep open-pit mines and develop recommendations for mine planning. The

variety of mining-and-geological, technical-and-economic conditions of mining

enterprises predetermines the use of flexible multivariate methods of simulation

model structuring. The use of the findings obtained for the conditions of a

particular field requires a comprehensive in-depth study of the complex features of

the current or an intended open-pit mine.

2 Model DevelopmentThe objective of the simulation model development in this paper is to substantiate

the most reasonable performance measurement definition of the technology

solutions suggested for the lower subsurface levels development of open-pit

mines. A comprehensive assessment of conditions for technical solutions requires

a preliminary analysis of all the factors that may exert influence on the decisionmaking

process. The diversity of the mining industry conditions predetermines the

required flexibility in the master data and the feasibility of adjusting the modeling

performance criteria.

While it is difficult to evaluate in monetary terms the non-economic criteria of


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the project, which include environmental and social performance of the project,

the cost-effectiveness of the latter can be presented with a minimum of

restrictions.

The most important feature in determining the efficiency of open-pit mine deep

levels development, is the need for working platforms for the implementation of

certain technical solutions. Such platforms are required to accommodate the

equipment, allow for arrangement of dumping stations, including areas for

maneuvering and support activities, platforms for installation of equipment and

process operations. Besides, it is necessary to take into account the alternating

hardware performance under restrictive conditions, if any, at the lower levels of

open-pit mines. Should the open-pit mine working area be critically reduced due

to an arrangement of working platforms for additional equipment, an eventual

change in the applied technology may necessitate additional wall cutbacks. The

dynamics of deepening the open-pit mine comprise the arrangement of equipment

operation platforms with the latter's basement partially blocking the rock mass

area, making it impossible to develop such area segments while they are part of

the technological process. The time span of their existence is determined by the

life cycle of the equipment installed on such platforms.

A mineral deposit block model serves the basis for a simulation model that

contains information on the target site characteristics. Any software products with

a block model development function may be used to create a block model.Modeling Development of Deep Horizons of Open Pits 45

Micromine 14.0.1 Mining-and-Geological Information Management System

has been used in preparing the present paper. That software provides a full set of

open-pit mine technical and economic indicators studies required by the

simulation algorithm.

The open-pit mine deep levels development simulation model aims to:

evaluate the efficiency of mineral deposit or part-of-mineral-deposit

development, with the use of the proposed technologies;

compare the competing methods of mining operations at lower levels;

develop a methodological basis for mine planning, taking into account the

specific features of the proposed technologies;

analyze the impact of various factors on the mining operations, and define the

main dependencies and ways to manage them;optimize the parameters of the technologies under consideration.

The structure of an open-pit mining subsurface development simulation model

consists of a system of master data blocks, a data storage and structuring unit and

a results analysis unit. The master data blocks are represented both by endogenous

and exogenous factors. The output parameters are the characteristics of the studied

technology solutions as applied to the major deposit field or the mining enterprise

and recommendations on the use of resource-saving technologies for the

development of the lower subsurface levels of open-pit mines, formalized as

technical and economic parameters of the proposed technology solutions and

illustrative graphic materials.

The master data block determines the specific costs of the main technological

processes and the costs of the facilities. The cost of restraining factors, adjustment

regulations and initial dependences shall be determined. In addition, marketdetermined

costs of the open-pit mines production shall be assessed.

The spatial characteristics of the simulation modeling are represented by the

process platforms required for the studied technologies, the location coordinates of

technological facilities, and the characteristics of dedicated zones, such as zones

of exclusion. The adjusting factors determine the calculations parameter variations

for such areas, for example, the amount of losses and dilution.

The simulation process is finalized by the analysis of the received technicaleconomic

indicators, the development of the final graphic indicators and the

rationale for the recommendations addressed to the mining company.


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The target function of the model is represented by the dominant criterion,

which determines the purpose of the process under consideration, - the Net Present

Value. Necessary constraints in achieving the objectives shall be described by the

(main and subordinate) economic and non-economic criteria. The subordinated

economic criteria are NCF (net cash flow), the cost of manufacturing and other

economic criteria.

The Current Net Present Value criterion serves to determine the time limits.

Current Net Present Value (CNPV) calculating which all points of time graph are

the moment of conversion consecutively.46 B. Nikolay

CNPV for each point of the graph is defined as the sum of the Net Values (NV)

at the subsequent period of the process [1].

,where

Nis current in-service time of equipment, years;

is the discount rate, unit;

tis the period between the currentN value and year of receivingNV, years.

In general, the constraints are taken as the limits of the model variables value

changes or conditions of their changes.

3 Technological SolutionsMechanical destruction of hard rock, technologies enabling the development of

mineral resources without overburden dumping, as well, inclined conveyors are

considered as resource-saving technologies for subsurface open-pit mine

development.

Drilling and blasting operations are the most common way of deep layer hard

rock loosening at the open-pit mines. However, that method entails a significant

environmental damage associated primarily with air pollution and seismic

impacts. Drilling and blasting operations in deep layers require arrangement of

operation platforms and protected areas for the preparation of massive explosions.

In addition, special measures need to be undertaken to ensure the safety of blasting

operations and neutralize their after-effects.

Mechanical destruction of rocks helps to avoid such negative effects. The

advantages of using the mechanical method at deep layers consist in:

Improved air quality;

Reduced mining equipment down-time;

Reduced surface area under the operating platforms;

Increased open-pit mines wall stability;

Possibility to use conveyor transport without causing further rock

disintegration;

Improved safety of mining operations;

No oversize boulders.

The high strength and diversity of rocks is a limiting factor in the use of

mechanical destruction method. Ensuring the scope of work for the rocks

mechanical disintegration requires homogeneous characteristics of the rock mass,

matching the intended performance of the mining equipment.In addition, it is necessary to monitor the changes in the configuration of the

area of mechanical rock disintegration against the backdrop of the open-pit mine

deep layers' development dynamics. If required to simultaneously use the

mechanical disintegration and the drilling-and-blasting method of rock

disintegration, the effectiveness of the mechanical method is greatly reduced.Modeling Development of Deep Horizons of Open Pits 47

Highwall System Application can significantly reduce the cost of mining and

environmental damage. However, the application research findings at the existing

coal strip mines show the complexity of cadenced production planning and a high


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proportion of a commercial mineral loss. It can, therefore, be assumed that

an unequivocally effective application of this method is circumscribed to the

deposit field areas where it is difficult to arrange for the overburden rocks

removal. Furthermore, a package of measures is deemed necessary to ensure the

technological processes correlation within the open-pit mine.

The most effective and almost surface-relief-independent means of

transportation can be ensured by cargo-carrying wire cableways. However, the

shuttle-like nature of the tote-a-load bearing capacities leads to their lower

performance than that of the conveyor systems. Widespread in open-pit mining,

belt conveyors involve the transfer of effective tractive effort via the load-bearing

belt, which limits the length of the conveyor lines and requires the use of a high

tensile stress resistant belt.

Cable-belt conveyors intensively introduced into service in recent years are

devoid of such a drawback. In their design, transfer of effective tractive effort is

provided through the traction rope. To ensure frictional engagement with the

traction rope, the conveyor belt is equipped with special arched clips.

Along with a number of advantages of cable-belt conveyors application in

open-pit mining operations, it requires the use of an expensive special conveyor

belt. Additionally, as in a conventional conveyor design, its installation requires

high precision construction operations while setting up the base platform.

To combine the advantages of the cargo wire cableway and the cable-beltconveyor, a design of a suspended cable-belt conveyor has been proposed [2].

That structure suggests a conveyor line consisting of a frame with a conveyor

belt fixed at the bottom. At the top, the frame has a carrying roller moving with

the frame on the track cable. The effective tractive effort is transmitted via the

traction rope, which has a frictional connection with the frame by a clamping

device disposed in the upper portion of the frame.

The conveyor of such a design is placed on a track cable stretched between the

supporting masts. Such a design conveyor allows for its track to be suspended

above a motor-road.

Thus, the proposed design combines all the benefits of cable-belt conveyors

and aerial ropeway. Summarizing the positive characteristics of two types of

transport systems provides a synergistic effect, resulting in a more efficient use of

a suspended cable-belt conveyor at the deep leers of coal strip mines.The advantages of a suspended cable-belt conveyor are as follows:

Low materials intensity, ease of manufacturing and structural assembly;

The use of a simple and cheap conveyor belt;

The possibility of suspending the conveyor above motor-roads;

Feasibility of setting up traction installations along the conveyor line track;

Feasibility of creating polygonal conveyor lines at the edge of an open-pit mine

without construction of special power-drive stations;48 B. Nikolay

Moving larger rock pieces than conveyors of a conventional design with the

same belt width;

Low labor intensity of installation, maintenance and repair of the transport

system;

A significantly lower energy consumption of the transportation system.

Study of the process platforms' impact on the technical and economic

parameters of deep layers of open-pit mines implies designation of a rock mass

associated with the implementation of the process under consideration. Conveyor

lift technological platforms arrangement modeling (Figure 1) may serve an

example. The figure shows in different colors different phases of an open-pit mine

development in terms of the use of the autotruck transportation. The technological

platform for the conveyor and the dumping station is the apex of a prism within

which no mining activities are allowed. In blue color, the figure shows a reference

prism.


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Fig. 1 The lay-out of an open-pit mine with an inclined conveyor

An important part of the study is to determine the dynamics of the open-pit

mine operation area with account of the area blocked by the process platforms

used for technological applications.

Figure 2 shows the change in the operation area, compared with the base

technology for phased out uniform development of deep open-pit mine layers.

The cone shows the inclined conveyor reference prism boundaries. Its

configuration changes the development sequence of the open-pit mine, with anegative impact on the open-pit mine development efficiency increasing with the

increase in depth of the open-pit mine.Modeling Development of Deep Horizons of Open Pits 49Fig. 2 Reference prism for inclined conveyor process platform placement

Therefore, when modeling the deep open-pit mine layers, the study of the

operating area development dynamics is carried out with due account of the

feasibility of applying the inclined conveyors design as easily mountable and

portable.

4 Deep Horizons StudiesThe study contributed to determining the economic effect of mining development

using three mining technology options (Figure 3): truck transportation,

conventional conveyor transport design, and a suspended cable-belt conveyor.

Fig. 3NPV comparison using different technologies0

200

400

600

800

1000

1200

1400

1600

Trucks Conveyor SCBC

50

The most expensive

transportation. A significathe conveyor transport, ev

the open-pit development

The maximum effect is

The boundaries of the

open-pit mine layers dev

reducing market value ofFig. 4 The boundaries ofreducing cost of production

The criterion for deter

Current Net Present Valu

changes depending on th

deposit mining boundarie

graph of changing CNPVwhen the cost of extrac

economically viable mine

three times. With the us

CNPV values enter the ne

Meanwhile, only half o

price on products, the us

the total volume of the lic

-50

0


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50

100

150

200

1 2 3 4 5 6

Trucks

B. Nikolaand least effective option in mining is the autotruc

ant increase in efficiency occurs with the introduction o

ven in spite of the deviation from the optimal schedule o

.

s achieved by using a suspended cable-belt conveyor.

e use of technologies under consideration for the dee

elopment are the limits of the deposit field mining wit

extracted minerals.the use of different transportation options with account

rmining the limiting boundaries of open-pit mines is th

ue. The comparison diagram of the critical CNPV valu

he use of various technologies confirms the minimum

es when the truck transportation is used. Figure 4 shows

V values with the use of truck transportation technolog

cted minerals is reduced by 30%. The volume of th

eral resource extraction is, meanwhile, reduced by abou

se of the conventional conveyor transport system, th

egative zone when the prices on products fall by 40%.

of the licensed reserves are being extracted. At the sam

e of a suspended cable-belt conveyor allows for minin

censed reserves.

7 8 9 10 11 12 13 14 15 16 17 18 19

Conveyor SCBC

ay

ck

of

ofep

thof

he

ue

m

a

gy

he

ut

he

me

ngModeling Development of Deep Horizons of Open Pits 51

5 ConclusionIn mining simulation, it is advisable to use a criterion that characterizes the

remaining life cycle of the facility under consideration at any given moment in

time. The Current Net Present Value (CNPV) serves such a criterion with all the

points of time schedule graph used consistently as reduction factors in the

calculation. The use of that criterion is practical in determining the boundaries of

open-pit mining, the expiry of the mining equipment life cycle, and the deadline

for a technological solution application.


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A variety of key economic indicators predetermine the multivariant iterative

algorithm structure of the simulation model calculation. An important feature of

the analyzed system is the dynamics of open-pit mines' spatial parameters with

due account of certain areas blockage by process platforms at the lower levels of

the open-pit mining.

The simulation results show that the use of conveyor transport at the open-pit

mine lower levels may adversely affect the mode of mining operations due to the

blockage of individual open-pit mine areas by the process platforms, as needed.

However, the overall effectiveness of the deposit mining is greatly enhanced. The

greatest effect is achieved by using a suspended cable-belt conveyor. When the

market value of the mineral goes down, such technology allows for the maximum

scope of the mineral reserves mining.Acknowledgement. The work has been performed under the public contract

No.14.515.11.0024 of the Ministry of Education and Science of the Russian Federation ofMarch 20, 2013.

References1. Belyakov, N.N.: Adoption of economic criteria for quarries development modeling.Coal Monthly Science and Technology, Industry and Economics Magazine (6), 2829

(2013)2. Belyakov, N.N.: ZAO FPK INVESTTEK, Cable-belt conveyor. Application for thegrant of a patent on utility model of the Russian Federation No. 2013135589 dated30.07.2013, Federal Institute of Industrial Property, FIIP

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Modeling Development of Deep Horizons