carrie hartford, jenike & johanson pty ltd, evaluating transfer chutes with increased throughput

Evaluating Transfer Chutes with Increased Throughput Bulk Materials Handling Conference 2014

Carrie Hartford Senior Engineer

Perth Western Australia [email protected]

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SCIENCE ⏐ENGINEERING ⏐DESIGN

WE ARE: A specialized engineering firm focusing on

providing clients solutions to material handling applications

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COMPANY PROFILE

� Incorporated in 1966 by Dr. Andrew Jenike � World’s largest firm specializing in materials flow � About 80 personnel world-wide � Offices in Australia, Brazil, Canada, Chile, USA � 7,500+ projects world-wide � Over 11,000 bulk materials tested � 650+ man-years experience

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OUR MISSION

To create value by assisting clients to improve the efficiency, reliability, and safety of their operations by preventing, eliminating, or

reducing problems related to bulk materials flow, storage, or processing.

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OUR APPROACH

We use a scientific approach, based on the characteristics of the materials handled and

process requirements.

It is not a trial & error approach!

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OUTLINE

� Review common transfer chute designs � Discuss typical transfer chute problems � Evaluate increasing throughput with existing

infrastructure � What about different material handled through an

existing system?

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VARIOUS CHUTE DESIGNS

For free-flowing rocky material: � Rock box � Micro ledges

Minimise wear.

For fine, sticky material: � Hood and spoon � No ledges

Prevent plugging and minimise buildup.

What if the material is rocky and fine and sticky? � Prevent plugging and minimise wear

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ROCK BOX CONFIGURATIONS

Use rock boxes only if material is free-flowing

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Cement Clinker Iron Ore


ROCK BOX CONFIGURATIONS

Rock box with sticky bauxite leads to frequent head box plugging

Heavy residual left in head box

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HOOD AND SPOON DESIGN

� Developed in early 1980’s by Jenike & Johanson (US Patent 4,646,910 - August 1985)

� Design reflects novel approach to controlling the material

� Minimises dust generation, centers the load on the receiving belt

� Minimises wear of the receiving belt by giving the load a velocity in the direction of the receiving belt

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Sticky fines on impact plate leading to frequent plugging

Proper stream capture with hood (low impact angle)

Proper stream control with spoon

US Patent 4,646,910

Rhino horn

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COMMON CHUTE FLOW PROBLEMS

� Plugging � Wear of chute surface � Spillage � Buildup � Dust generation � Excessive belt wear

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Plugging


EXAMPLE CHUTE FLOW PROBLEMS

Wear of chute surface

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EXAMPLE CHUTE FLOW PROBLEMS

Spillage

Buildup 14


IMPACT ANGLE & SLIDING FRICTION

V2 = Velocity along chute after impact

V1 = Impact velocity θ = Impact angle φ’ = Wall friction angle

θ

V1

V2

V2V1= cosθ − sinθ tan "φ

Impact angle and sliding friction is critical in chute design: If θ + φ’= 90°, no resultant velocity

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QUESTIONS ASKED TO MAXIMISE USAGE OF EXISTING PORT INFRASTRUCTURE

� Can we increase the throughput of the same material through the existing design? Consider: �  Belt sizing and speed �  Loads on the belt �  Support structure �  Material flow through the chutes

� Can we put a different material through the existing transfer chutes? �  Example: handling magnetite concentrate in iron ore transfer chutes

� What are the implications? �  Will material flow through the chutes?

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CASE STUDY

� Iron ore export terminal in South Africa � Belt width: 1650 mm wide � Belt speed: 5.5 m/s � Flow rate: 10,000 tph � Right angle transfer chute

� Rock box used to minimize wear

� Client needed to increase throughput.

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CASE STUDY

� By using rock boxes, the chutes did not wear, but as the flow rate increased, the chute began to plug frequently leading to: � Cascading shutdown of upstream conveyors � Belt tracking problems � Spillage � Dusting � Inability to obtain desired throughput

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Increase in fines, mc, & flow rate

Buildup in the chute (eventual plugging)

Changed the flow

path through the

chute

Changed the way material

exited the chute

Spillage, dusting, & premature belt wear

PROGRESSION OF PROBLEMS

Iron Ore

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TO ANALYSE AND DESIGN CHUTES

•  Bulk density •  Coefficient of sliding friction •  Particle size •  Particle density •  Chute tests

•  Angle of repose •  Drawdown angle •  Wear tests •  Angle of internal friction

Flow properties tests needed:

Angle of repose Drawdown angle


Wear results vary and are dependent on material characteristics such as particle size, shape, and abrasiveness of particles

WEAR TESTS

AR 500

Test results are for example only

Alumina Ceramic

Arcoplate

Wear ratio (wear/

distance moved)

Pressure

Adjustable force

Bulk material In hopper

Collecting Drum

Screw Feeder

Wear coupon mounted in rotating head

Proprietary J&J wear testing apparatus

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DEM ANALYSIS OF IRON ORE CHUTE

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Proper belt loading with spoon

Proper stream capture with hood

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Other benefits: � Minimal downtown – chute went 2.5

years before changing out the head chute, still not much wear in the spoon.

� Eliminated belt tracking problems � No spillage � Reduced dusting significantly � Obtained desired throughput

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OTHER ISSUES FROM INCREASED FLOWRATE

� Example: Material flies over the head chute

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Head chute height was set based on cross sectional area of material on

belt and material

trajectory.

Belt speed and cross-sectional area of material

on the belt increased to

increase throughput.

Caused some material to fly over the head chute. Chute was also fuller than designed

for.

Resulted in increased

spillage and higher plugging

potential.


CHANGING MATERIAL

� Example: Using magnetite in hematite handling systems with rock boxes

� Cycle times of fine, sticky material versus lump ore needs to be evaluated

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CONCLUSION

� Increasing throughput and/or handling different material through existing infrastructure can have significant financial benefits.

� Material testing and DEM are good predictive tools to analyse the feasibility of a usage change.

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QUESTIONS?

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Carrie Hartford Senior Engineer

Perth Western Australia [email protected]

www.jenike.com

carrie hartford, jenike & johanson pty ltd, evaluating transfer chutes with increased throughput

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