Peter Wypych - Bulk Materials Handling Engineering Australia

Conveyors Conference, 23-24 Sept 2014, BrisbanePeter Wypych, Bulk Materials Engineering Australia

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Improving Reliabilityof Conveyor Transfers

Peter [email protected]

Conveyors Conference23 – 24 September 2014, Stamford Hotel, Brisbane

1) Bins, hoppers, stockpiles, feeders, bin wall loads…

Arch/rathole dimensions

Bin/hopper design graphs

Stockpile/bin live capacity

Transport moisture limit

Flow patterns: mass-flow, funnel-flow and expanded-flow

Quasi-static applications

Traditional FP (sub 4mm): b, , t, w, FF

CT Design & TroubleshootingTests?Data? Design Methods?

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Typical FlowProperties

Dangerous toExtrapolateor Assume!!

Internal Friction

Wall Friction

Internal Strength

Compressibility

Relevant to CT ?

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Flow Functions – Coal 10% wb(effect of time storage)

FF, t = 0

FF, t = 2 days

5 days ??

Relevant to CT ?

1. Impact consolidation2. Higher wall friction3. Fines Segregation…4. Higher w and MC5. Rhino-horns…

1 (kPa)

c(kPa)

0 2 4 6 8 10 12 14 16

20

18

16

14

12

10

8

6

4

2

0

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FP Effect ofMoisture on

ProcessRequirements

DEMC Saturation

Max Strength

Conical

Wedge

BMEADustiness Tester(AS4156.6-2000)

Relevance to CT ?

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Dustiness Test Issues

Ore at 8.1% wb

(DEMC = 11% wb)

Conc at 1.6% wb

(DEMC = 2.8% wb)

…Possible CT Handling/Flow Problems!!

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Conventional FP Useful but not adequate Physical size of FP testers Inadequate Friction, cohesion and adhesion Difficult

to scale (dynamic applications) Traditional design methods Limited Extra design considerations: Continuity;

Wear; Re-start; Transients Fine/sticky/clay ores Special impact tests

2) CTs (hood-spoon, impact plate, rock-box, micro-ledge, trajectories, impacts).. “Dynamic” applications:

CT Design & TroubleshootingTests?Data? Design Methods?

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Quasi-Static vs “Impact” Wall Friction

Jenike

IST

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Quasi-Static vs “Kinetic” Wall Friction

BMEA “Large-Scale”Shear Tester

JenikeShear Tester

Full-Size Products Kinetic Friction Variable Shear Rate High Pressures

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Dynamic Impact Tests

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Obstructions to Flow in CT

(1) Poor “Continuity” Design

ms1 = b1V1 A1

ConveyorTransfer

< ms1ms2 = b2V2 A2

msn = bnVn An

Transients??

Carry-Back Spillage Dust Emissions Fines Build-Up

Extra Flows?

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CT Chute – Poor Continuity Design

Video 1 Video 2

Root Cause of Problem ??

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(2) Material Build-Up

Obstructions to Flow in CT…

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CT Chute

Solution??...Air Cannons??

Treating Symptom !!

Root Cause of Problem ??

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Traditional Design Methods1. Experience (including “rule-of-thumb”)2. Trial-and-Error3. Copy-and-Paste4. Analytical or “Continuum” Models5. Physical Scaled-Down Models6. “Traditional” DEM Research…● Time consuming and expensive for design● Assumptions and fine-tuning● Also Lack of validation

At UOW New Calibration Technology (with dynamic validation) for DEM Design

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Full‐Scale Designs

Representative Dynamic Tests

New Calibration Technology for DEM Design

Industrial Application

Customer Know‐How

EDEMBulkSimCalibrated

Material Model

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Calibration for DEM Material Model(New “Swing Arm” Slump Tester: Coal)

Video

Video

PSD, shape, friction, moisture/cohesion

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Other Calibration Tests

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Dynamic Validation of DEM for Design

Conveyor TransferResearch Facility

7 m/s

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Video

Dynamic Validation of DEM for Design(Hood-Spoon Conveyor Transfer)

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Dynamic Validation of DEM for Design(impact plate CT)

Exp VideoDEM Video

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Parameter Value

Capacity 11,000 tph

Belt Width 1,800 mm

Feed Belt Speed 4.6 m/s

Boom Belt Speed 4.8 m/s

Luff Angle 15 deg

Slew Angle 45 deg

Bulk Density 1.9 t/m3

Troughing Angle 45 deg

Feed Belt Inclination 15 deg

Chute LinerCeramic

Tile

Moisture Content 10% wb

Case Study No. 1:Iron Ore Stacker Transfer Chute

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Design Problems:• Dead Zones• Potential Blockage• High Wear on Boom: Chute; Belt

Costs to Business:• Downtime• Limited Capacity (incl. surges)• Maintenance – Skirting, Spillage

and Belt Replacement• Overall Poor Reliability

Problems and Costs

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Design Features & Outcomes:• New Hood, Mid-Chute and Spoon• Reduced Wear Rates• Improved Flow/Capacity (incl. transients)• Improved Product Acceleration on Conveyor• 20% Increase in Boom Belt Life

Calibrated Models Re-Designto develop Optimised Solution

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Case Study No. 2: WSO Chute Blockages

Full-Scale Calibration Tests On-Site+ Special Impact Consolidation Tests

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Design Features & Outcomes:• Completed Root Cause Analysis (blocked chute)• Re-designed Central Rock-Box (self-cleaning)• …to handle Product Variability• …with Improved Flow/Capacity• Stage 2 progressing

Calibrated Models Root-CauseAnalysis and Re-Design

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