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EQUIPMENT SELECTION

T

he period from the 1940’s to the 1980’s saw an emphasis on in-

creasing the size and capacity of materials handling equipment.

This increase in equipment size improved economies of scale andprovided the desired higher efficiencies which were sought.

From the 1980’s onwards, two additional trends have emerged

in material handling equipment development and selection:

• In some cases, in pit crushing and conveying reduce the reliance

on trucks for material transport in mining operations.

• The information age has seen an increase in automation of equip-

ment and has reduced the number of operators required.

This paper discusses the various types of material handling sys-

tems and equipment, their features and criteria for selection. Future

trends regarding mine automation are also discussed, including the

use of remote operations centres where drills, trucks and driverless

trains are proposed to be controlled from distances of over 1,000

km away.

IntroductionThe period from the 1940’s has seen a continued increase in the size

of materials handling equipment for the mining industry. This paper 

investigates four areas of change and outlines some basic criteria for 

a broad brush approach to appropriate equipment selection during

a project’s concept study phase:

Overland transport The development of overland conveyors has brought a new dimen-

sion to the evaluation of transport economics in the mining indus-

try. The latest of these conveyors have single flights in the order of 

20 km in length and are now supplanting road and rail transport for 

many of the shorter haul applications.

Underground transport The use of winders, which was once a given for deep underground

mines, is now being challenged by the use of high-lift conventional

troughed conveyors. Single lifts of up to 400 m per conveyor flight

 with total lifts of 800 m have been achieved.

Mobile and semi mobile crushing plant Large scale mobile and semi mobile crushing plants have found

particular use in mines where the design life is relatively short, or 

the mine plan dictates long transport distances because of scattered

deposits.

 AutomationThroughout the period from the 1970’s through to the 1990’s, au-

tomation of separate plant items developed. The latest trend is to-

 wards the amalgamation of individual control hierarchies to provide

an automated, remotely controlled mine.

Overland transportImprovements in belting material through the 1950’s and 1960’s

have made it possible to design and construct longer convention-

al troughed conveyors.

 As belts became longer, it became apparent that issues arising

from dynamic transient stresses during acceleration and deceler-

ation would have to be analysed in order for successful designs to

be undertaken. The work of Funke and others in the field, along

 with the advent of the digital computer, provided the means for 

designing conveyors of ever increasing length during the 1980’s

and 1990’s.

These new design tools also allowed for the inclusion of verti-

cal and compound curves (combination vertical and horizontalcurves). It is now possible to design and construct belts as sin-

gle flights of 20 km in length which follow the terrain. Figure 1

presents the trend over time for overland conveyor length.

Based on work done on various projects globally, the guide-

lines in Table 1 may be applied to the application of conveyors

in mining. The costs referred to in Table 1 are based on whole

of life costs.

The information in Table 1 is based on the following assump-

tions:

• The terrain is flat and requires minimal civil work. For excep-

tionally treacherous terrain and shorter distances, conveying

systems such as Ropecon may be considered.

• The design life of the plant is in excess of 8 years.• The cost of diesel is approximately USD 1.00 per litre.

• The cost of electric power is approximately USD 0.20 per 

kWHr.

• The all inclusive average labour cost is approximately USD

180,000 per person per annum.

Material transportation in mining– trends in equipment

development and selectionPeter Saxby¹ and John Elkink² of Hatch

Conveyor Length (Single Flight) Over Time

    L   e   n   g   t    h    (    k   m    )

Year

0

5

10

15

20

25

1985 1990 1995 2000 2005

Figure 1. Trend o Conveyor Lengths (single fight) Over Time.

 This paper discusses the various types of material handling systems and equipment, their features and criteria for

selection. Future trends regarding mine automation are also discussed, including the use of remote operations

centres where drills, trucks and driverless trains are proposed to be controlled from distances of over 1,000 km

away.

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EQUIPMENT SELECTION

The period from the 1980’s to now have seen significant evo-

lution and improvement to the design of mobile and semi mobile

plants. Following are some of the changes that have resulted in

trends towards increased use of these units:

• Relocations are now completed in days (typically 7 days) rath-

er than weeks.

• Sizers are now available and can be used in lieu of gyratory crushers, particularly for lower strength rock. This results in

significant weight and height reductions.

• Through design innovations the requirement for retaining

 walls and footings has been reduced or eliminated for some

installations.

• The reduction in relocation times and elimination or reduction

of civil works have resulted in reductions in relocation costs

  An important point to note when conducting a trade off 

study between a semi mobile or fully mobile and a fixed plant,

is that the capital cost is likely to be similar. The factor that will

often swing a decision to semi mobile or mobile plant is often

the reduction in operating cost arising from a reduction in the

trucking fleet. The following points are made in relation to this:

• Taking into account operating and maintenance crews, be-tween 5 and 7 persons per truck can be saved.

• Reduction of the trucking fleet can improve safety perform-

ance – fewer trucks result in less congestion.

• Some manufacturers have proposed fully mobile plants which 

follow the face shovels and thereby eliminate the haul truck 

fleet. Movable conveyors transport the material to a fixed

plant for further treatment.

There are risks associated with the selection of semi mobile and

mobile plant and these need to be assessed. Some of the risk factors

associated with using mobile and semi mobile plant include:

• Failure to achieve operating hours due to inability to relocate

in the required time.

• Potential to blast damage. Mining can not occur above any ramp conveyors due the risk of damage from fly-rock.

• Delivery times for the larger semi mobile units can be substan-

tial (up to 24 months in some cases).

Table 2 provides some broad guidelines to assist in determin-

ing where the different types of plant can be used.

The figures in Table 2 have been derived from various stud-

ies using financial models. The assumptions for the parameter 

inputs are similar to those used above for overland transporta-

tion selection.

Other considerations to take into account when evaluating

crushing plant type are listed below. Importantly, any financial

calculations for mobile or semi mobile plant should take these

factors into consideration for the calculation of relocation costs

and ongoing costs.

• Footings that may be required. Some semi mobile plants are

now available with built in steel pads as footings, but these

need to be assessed on an individual project basis, taking into

account local geotechnical considerations.

• The cost of electricity and diesel fuel has significant bearingon the outcome of any analysis. Accurate costs for these com-

modities at the mine is required.

• Services and utilities that will be required. Any relocation of a

crushing plant will require that associated services are moved

accordingly.

• Lost production associated with plant relocation needs to be

considered.

• The costs of relocation need to be factored into the financial

case (hire of heavy transport equipment and crews, etc).

• In some cases, maintenance of semi mobile and mobile crush-

ing plant will be more difficult in comparison to fixed plant,

  which is usually designed with superior access and inbuilt

craneage. An allowance may need to be included for mainte-

nance costs in any financial analysis.

AutomationThe trend towards automation of equipment has been with us since

the industrial revolution. Prior to the 1940’s, mechanical logic was

the mainstay of many automated systems. The period from the

1940’s to the 1980’s saw relay logic take centre stage. Now comput-

ers combined with GPS and communications systems are coming to

the fore as an impetus in automation.

The period from 1990 to the present has seen an almost uni-

 versal use of integrated circuit technology. This has allowed for the

automation of complete units of plant with control from a central

control room. Examples of this include:

• Automation of stockyard stackers and reclaimers. Along with au-tomation of the associated conveyor and sampling systems, the

net result has been the complete automation of product stock-

 yards.

• Train loading systems. These have been automated to detect the

arrival of trains, determine the wagon size and fill accordingly. In

addition to this, these systems have been refined to meet strict

loading criteria from the rail authorities in regards to overweight

and underweight wagons and axle load distribution.

• Driverless trucks and bulldozers. Advances in GPS and commu-

nications systems, combined with the use of computers, have led

to the advent of driverless or remote controlled vehicles.

• Underground mines. Improvements in

communications technology are providing

greater opportunity for remote control andautomation of equipment.

The latest trend is now to move one level

up in the hierarchy and have complete auto-

mation of the mine with drills, shovels, trucks,

train loading and trains all being automated or 

controlled remotely. An experimental mine be-

ing planned by Rio Tinto has its central control

room over 1,000 kms from the mine.

ConclusionIn considering the type of equipment to be

used for a project, a financial analysis needs to

be conducted taking into account the capitalcost, operating cost, timing of expenditures and

timing of revenues. A number of studies under-

taken by the authors have yielded benchmark 

figures and trends which influence equipment

selection.

Type of Plant

Selection Criteria

Mine PlanPeriod Between

RelocationCapacity

Fixed Plant

Discrete deposit withtrucking distance less

than 8km

Planned plant designlife to exceed 8 years

(no relocation).

N/A

Semi Mobile

Deposit which is

spread out and re-quires truck haulage

in excess of 8km

Planned periods

between relocationsof between 2 and 5

years.

Up to 10,000 tph now

possible

Mobile

Deposit which isspread out and re-

quires truck haulagein excess of 8km -

Can completely avoidusing trucks

Planned periods be-tween relocations in

the order of months(or less)

1,000 tph available,5,000 tph systems

proposed (usuallylower rock strengths

<70 MPa)

Table 2. Guidelines or the Selection o Crushing Plant.

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EQUIPMENT SELECTION

• Overland transport has seen a trend away from trucking on

routes under 40 km and a shift to overland conveying systems.

The length of single f light conveyors has increased four fold over 

the last 20 years.

• Underground mine transportation systems have been tending

to use conveyor technology in favour of shaft winder systems

in mines up to 1,000 m in depth. The ability to load primary 

crushed rock onto higher speed belts (3 to 4 m/s) along with single flight lifts of up to 400 m have been behind this trend.

• In pit crushing is being used in situations where dispersed depos-

its would result in haul distances requiring large truck fleets. In

pit crushing plants have also found favour in operations where

the design life is relatively short, or the mining operation dictates

that the plant requires relocation on a regular basis.

• Mine plant is currently automated to level where the individual

components from the ROM to the product handling area are con-

trolled from a central control room. The latest trend is to move

this central control room off site and incorporate all mining

transport operations (drilling, shovels, trucks and rail) into the

control system. Due to the rapid advances in this area and the

significant effect they are likely to have, any study should specifi-

cally address the latest trends in automation to ensure the projecttakes advantage of the latest technology.

AcknowledgementsThe authors wish to thank Hatch Ltd. for providing the resources

and time for the preparation of this paper.

References

[1] Hager, M. & von der Wroge, H.: Design of Steel Cord Conveyor 

Belt Splices; Bulk Solids Handling, Volume 11 (1991), Number 4, pp

849 – 860.

[2] Nordell, L.K.: The Channar Overland Conveyor – A Flagship of 

Modern Belt Conveyor Technology; Bulk Solids Handling, Volume

11 (1991), Number 4, pp 781 – 792.

[3] Steven, R.B.: Belting the World’s Longest Single Flight Conven-

tional Overland Conveyor; Bulk Solids Handling, Volume 28 (2008),

No 3, pp 172 – 181.[4] Rio Tinto and GE combine ‘Mine of the Future’ and ‘Ecomagina-

tion’ - Rio Tinto Media Release (18 September, 2008). http://www.

riotintoironore.com/ENG/media/38_media_releases_1657.asp;

 viewed 25 July, 2009.

[5] Nordell, L.K.: Palabora Installs Curved Transfer Chute in Hard

Rock to Minimise Belt Cover Wear; Bulk Solids Handling, Volume 14

(1994), Number 4, pp 739 – 743.

[6] Lodewijks, G.: Two Decades Dynamics of Belt Conveyor Systems;

Bulk Solids Handling, Volume 22 (2002), Number 2, pp 124 – 132.

[7] Funke, H., Hartmann K. & Lauhoff H.: Design and Operating

Performance of a Long Distance Belt Conveyor System with Hori-

zontal Curves and Simultaneous Material transport in the Upper and

Lower Strands; Bulk Solids Handling, Volume 20 (2000), Number 1,

pp 45 – 55.[8] Hinterholzer S., Kessler F. & Garbner K.: Garland Stations to

Run Through Horizontal Curves; Bulk Solids Handling, Volume 21

(2001), Number 4, pp 424 – 430.

¹ Hatch Ltd. 61 Petrie Tce., Brisbane, Qld, Australia.

² Hatch Ltd. 700, 840 7th Ave SW, Calgary, Alberta, Canada.

Contact: Peter Saxby – email: psaxby@hatch.com.au

Contact: Nu-Con Australia Pty LtdNSW - 02 9545 2600

VIC - 03 9554 3125

QLD - 0400 418 794

Email: sales@nucon.com.au

Website: www.nucon.com

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