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Mobile Crushing and Screening Plant Applications for Small to Medium

Sized Iron Ore Projects

Presented by Damian Connelly

Mineral Engineering Technical Services

> RESOURCE PROJECTS > TECHNOLOGY > INTEGRATED SERVICES > Mineral Processing > Engineering Design > Training > Specialist Services

> DISCLAIMER With respect to all the information contained herein, neither Mineral Engineering Technical Services Pty Ltd, nor

any officer, servant, employee, agent or consultant thereof make any representations or give any warranties,

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including but not limited to opinions, information or advice which may be provided to users of the document.

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electronically or otherwise, is not permitted without the expressed written consent of Mineral Engineering

Technical Services Pty Ltd.

> ACKNOWLEDGEMENTS This document is a dynamic record of the knowledge and experience of personnel at Mineral Engineering

Technical Services. As such it has been built upon over the years and is a collaborative effort by all those

involved. We are thankful for the material supplied by and referenced from various equipment manufacturers,

vendors, industry research and project partners.


Who We Are

Mineral Engineering Technical Services

> Engineering Consultants with a focus on junior and mid-tier mining companies

> Mineral Processing since 1988

> Global greenfields and brownfields project experience

> Guiding projects through the development path from testwork to feasibility studies through to commissioning

> Commodity experience across a wide range minerals


Crushing is fundamental and common to all mineral processing

operations

Typical crushing plants are on a fixed base on heavy concrete

foundations and structural steel

Basic units: primary, secondary and tertiary crusher, plus a screen and

conveyors

Gyratory or jaw crushers are used for primary crushing

Cone or impact crushers are used for secondary/tertiary crushing

Horizontal, double deck inclined or banana screens are used for

screening

Introduction


Crushing Fundamentals

Source: Ferret website (2012)

Source: Pennsylvania Crusher website (2012)

Source: Mining Technology website (2012)

Source: Science Direct website (2013)


Typical Flowsheet


Mobile plants started on a very small scale with roadside batch crushing

In particular, gravel quarries located near road works

Scale 10 to 50 tph

Larger scale mobile crushers are now available up to 625 tph

In-pit crushing has made a major contribution, driving mobile crushing for both

waste and ore removal

Overland belt conveyors have facilitated this

History


Ore characteristics are critical

Ore moisture level: dust generation

Wet sticky clay ore problematic

Abrasive index Ai, Unconfined Compressive Strength (UCS),

Crushing Work Index (CWI), critical characteristics

Tunra tests

Ore characteristic variability

Ore Characteristics


> Hazards of dusts

> If diameter of dust less than 10μ it is respirable

> Respirable dust provides health hazards

> Silicosis

> Chemical properties of dust determine level of hazard

> Coal, silica and some others can cause irreversible lung damage

> Combustible particles pose explosion hazard

Safety & Environment

Source: Wikispaces website (2013)


Crushers

Feeders, bins

Screens

Storage bins

Conveyors, magnets, sampling stations

Rock breakers

Crusher & Screen Selection

Loading skirtsFeed chute

Tail pulley

Conveyor belt

Idler rolls

Head pulleyReturn idlers

Vertical gravity take-up pulley

Discharge chute


Conveyors

Belt rip detectors

Belt washing stations

Tracking conveyors

Conveyors


Mobility and flexibility is an advantage

Lower capital write off - scrap value $$$

Larger size of equipment now available

Track mounting improved mobility

Conveyors are more efficient than trucks for mass movement

Cost savings over using trucks: in pit crushing

Great for waste removal: in pit crushing

Safety is improved: fewer trucks

Advantages of Mobile Crushing Plants


Mobility of Plant

Source: Cape Crushing & Earth Moving Contractors website (2012)





Limited capacity

Multiple units required

Complexity

Designs are not as tidy as fixed plant

Mobility varies from manufacturers

Reluctance of operators to embrace the concept

Disadvantages of Mobile Crushing Plants


Where trucking is >50 km transportable plant stacks up

More suitable for higher grade projects

Project Applications

Source: Crusher Industry website (2013)


Equipment selection, layout, availability, production rate

Lump impact energy on conveyors

Handling dense ores

Types of mobile crushers

Loading arrangements, capacities, lump sizes & belt widths

Comminution characteristics

Ai

CWI

UCS

Design Considerations


Simplicity

Control rooms

Crib rooms clean up

Service points

Dust issues

Ease of mobility

Operational Considerations


Availability

Scheduled maintenance

Condition monitoring

Oil analysis

Critical spares

Wear liners

Cranes, contractors

Maintenance Considerations


Short term projects suit mobile plants

Additional trains, retrofitting

Oversized primary crushers

Good initial solution

Scrap value $$$ benefit

Life of Mine Expansion


Mobile plants are better suited to dry climates – no

buildings required

Not suited to arctic climates or snow

Issues with tropical wet seasons

Wet sticky clays are problematic

Climatic Considerations

Source: Troy Resources Website (2011)


Off the shelf: no design required

CAPEX for mobile plant is less than fixed plant

No buildings are required

Salvage value higher

Direct capital costs such as earthworks, concrete, structural steel is lower

Indirect costs are lower

CAPEX


Design Philosophy Small/Medium Plants

> Minimise the number of operations by keeping the flowsheet simple

> Generously size the mechanical equipment, unless we approach a step change in size or the number of units

> Minimise the overall plant footprint and the height of structures – Compact layout especially around low maintenance items such as tanks, thickeners and vessels

– Critically evaluate conveyors angles and lengths

– Use existing bins, tanks as structural support for screens and piping

– Minimise piping and cable runs

> Control the process from one point, minimise the number of control centres

> Don’t over-automate

> Provide a workshop in the work area


Design Philosophy Small/Medium Plants

(cont.)

> Minimise the operator skills needed to run the plant

> Minimise maintenance personnel and costs – Do not provide extensive on-site maintenance – Short access between maintenance shop-plant-stores – Provide permanent lifting facilities only where regular lifts needed

– Provide ready access around high maintenance equipment – Provide adequately installed stand-by facilities

> Use simple, robust equipment especially for projects in the third world

> Minimise the administrative and management facilities on site

> Optimise working conditions for safety

Note that the real cost of gold projects was approximately halved in the period 1980 to 1990 through application of the above principles


Typical Closed Circuit Crushing

Source: Grinding Mill website (2013)


Typical Closed Circuit Secondary & Tertiary Crushers



Two stage open circuit

Three stage open/closed circuit

Four stage open/closed circuit

Hybrid circuits with HPGR

Flowsheets


Two Stage Open/Closed Circuit



Three Stage Open/Closed Circuit



Four Stage Crushing Circuit



New Generation Systems Available

Modular systems with high

capacity

Designed for in pit crushing of

waste

Lower cost than trucking

High volume waste is driving

innovation

Track mounted equipment

for mobility


Mobile/Semi Mobile


Crushing plant flowsheet The mined ore contained 50% minus 10mm material. Given the Crushing Work

and Abrasion Indexes, the ore was considered to be not difficult to crush and not overly abrasive

The product from the surface mining did not require primary crushing. The ore was loaded into an apron feeder and fed to vibrating screens. The ore was first screened and the +30mm ore are removed and fed to the secondary cone crushers whilst the -30mm+10mm ore are fed to the tertiary crushers. All crushed product was returned to the screens. The screen undersize (-10mm

fines) reported to the radial stacker for product stockpiling

An automatic sampling station was included on the product stream with samples taken from the conveyor leading to the radial stacker

Examples DSO Iron Ore 5 mtpa Mobile


Production ramp up

The crushing plant would initially start processing 600 tph

during a single shift. Ramp up was over 18 months to 5 Mtpa

working 24 hours a day seven days a week

The crushing plant included a control room, real time

monitoring and is fully automated

The crushing plant was designed to meet the initial duty

working a single shift of 10.5 hrs/day

Examples Mobile Plant


In Pit Crushing Ore

Source: Citic Pacific Website (2010)

In pit crushing and conveying

> 4 mobile in pit crushers

> Largest installation in Australia

> Integrated into mine design

> Advantages

> Reduced atmospheric

contaminants such as dust and

carbon emissions

> Lower overall operating costs

> Fewer trucks required

> Reduced fuel usage

> Reduced manning


Equipment

The mining contractor supplied the following equipment to feed

the crushing plant:

> Crushing and screening of ore (the contractor crushing and

screening system)

> 3 by vibrating double deck scalping screen (30mm top

deck, 10mm bottom deck); (3.35m by 6.7m)

> 2 by secondary Nordberg cone crushers (CM500)

> 2 by tertiary Nordberg cone crushers (CM 500)

> Automatic sampling station

> 4 by 550 kVa diesel fired generator sets for power supply

> Radial stacker

Crushing Plant Flowsheet


Bruno Simulation – Mobile Example

Source: Metso website (2008)


Mobile crushing plants up to 5 mtpa

In pit crushing is driving mobile crushing plants: particularly high volume waste

Advantages are lower CAPEX and better salvage value

For large plants fixed crushing plants

Mobile plant not suitable for some climates

Mobile plants can be moved in less than 7 days

Smaller DSO iron ore projects are ideal

Conclusions


Acknowledgement

> Thanks to AusIMM for opportunity to present

> Thanks to various companies, colleagues, engineers.

> METS staff, Vendors and Consultants

> Thanks to laboratory staff


> Cape Crushing & Earth Moving Contractors. 2012. Mobile Crushing and Screening Plants. [ONLINE] Available at:

http://www.capecrushing.com.au/index.cfm?objectId=2D78C25D-1422-130F-330268DFA09DDEDA. [Accessed 09 October

12].

> Citic Pacific. 2010. Largest In-Pit Crushing System in Australia. [ONLINE] Available at:

http://www.citicpacificmining.com/articles/latest-news/largest-inpit-crushing-system-in-australia. [Accessed 09 October 12].

> Ferret. 2012. Metso Minerals (Australia) distributes Nordberg HP series cone crushers. [ONLINE] Available at:

http://www.ferret.com.au/c/Metso-Minerals/Metso-Minerals-Australia-distributes-Nordberg-HP-series-cone-crushers-n902742.

[Accessed 08 October 12].

> Metso. 2012. Process optimation tool - Bruno. [ONLINE] Available at:

http://www.metso.com/miningandconstruction/mm_segments.nsf/WebWID/WTB-081014-2256F-33D4A?OpenDocument.

[Accessed 09 October 12].

> Mining Technology. 2012. JOEST Australia - Bulk-Solids Handling Vibration Equipment. [ONLINE] Available at:

http://www.mining-technology.com/contractors/screening/joest/joest5.html. [Accessed 08 October 12].

> Pennsylvania Crusher. 2012. Jaw Crushers. [ONLINE] Available at:

http://www.penncrusher.com/Size_Reduction/Models/Jaw_Crushers.cfm. [Accessed 08 October 12].

> Troy Resources. 2011. Presentations - Troy Resources Corporate Presentation 2011. [ONLINE] Available at:

http://www.troyres.com.au/investor-centre/presentations.html. [Accessed 09 October 12].

References

http://www.capecrushing.com.au/index.cfm?objectId=2D78C25D-1422-130F-330268DFA09DDEDA







http://www.citicpacificmining.com/articles/latest-news/largest-inpit-crushing-system-in-australia













http://www.ferret.com.au/c/Metso-Minerals/Metso-Minerals-Australia-distributes-Nordberg-HP-series-cone-crushers-n902742





















http://www.metso.com/miningandconstruction/mm_segments.nsf/WebWID/WTB-081014-2256F-33D4A?OpenDocument







http://www.mining-technology.com/contractors/screening/joest/joest5.html



http://www.penncrusher.com/Size_Reduction/Models/Jaw_Crushers.cfm

http://www.troyres.com.au/investor-centre/presentations.html




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mobile crushing and screening plant applications for … · mobile crushing and screening plant...

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