De-bottlenecking Iron Ore Transportation From Mine to Plant. Corin Holmes MSc Eng. Project Engineer Jenike & Johanson Pty Ltd

Transcription

1 De-bottlenecking Iron Ore Transportation From Mine to Plant Corin Holmes MSc Eng. Project Engineer Jenike & Johanson Pty Ltd

2 What is a bottleneck? Defined as any point in the transport system where the desired flow rate or throughput cannot be achieved Where do bottlenecks occur? 2

3 Everywhere! SCIENCE ENGINEERING DESIGN 3

4 Why do bottlenecks occur? Increasing throughput in a system not designed for it Changing to a new type of material or blend which alters handleability Changes in material characteristics (e.g. finer material or increased moisture content) Changes in operational philosophy due to equipment availability or process utilisation 4

5 Where do bottlenecks occur? Stockpiles: limited live capacity leading to inadequate amount of ore feeding to system Bins & Hoppers: incorrect material flow pattern resulting in formation of a stable ratholes Rathole collapses can cause material to flood the downstream system Transfer chutes: pluggages or wear leading to downtime Ship loading: long settling or de-aeration time, exceeding TML 5

6 Consequences Decreased Production rates Throughput Increased Delivery times Operating costs SCIENCE ENGINEERING DESIGN 6

7 How to solve/eliminate bottlenecks Development of Bulk Material Technology Flow properties Clearly define/determine required flow pattern Measure material flow properties and match them to system Design the system accordingly Test/model the assumptions continuum methods, physical modelling, DEM 7

8 Methodologies for Solutions Flow Pattern Funnel Flow Flowing Stagnant 8

9 Methodologies for Solutions Flow Pattern Mass Flow All material is moving! Flowing First in first out flow sequence 9

10 Methodologies for Solutions Flow Pattern Which one? Mass Flow, if material is: Cohesive Fine Prone to caking Likely to segregate, degrade How to achieve mass flow? Must have flow along hopper walls Must prevent arching 10

11 Methodologies for Solutions Material Flow Properties Common characterisation tests Cohesive strength Wall friction Compressibility Permeability Chute testing Angle of repose Drawdown angle Belt surcharge angle Maximum belt inclination angle 11

12 Methodologies for Solutions Flow Properties, Particle size and distribution Moisture Time at rest Particle shape Temperature Relative humidity Chemical composition We need to test these! a function of It is critical to match your process conditions! 12

13 Methodologies for Solutions Flow Properties How Flow Proper es Change with Moisture Content Cohesive Strength High Medium Low Low Medium High Saturated Moisture Content 13

14 Methodologies for Solutions Continuum Models Continuum models developed by Jenike very reliable for large set of applications (ie. stockpiles, silos, hoppers) Incorporate use of measured flow properties Flow patterns can be predicted and designs can be determined to ensure reliable flow 14

15 Methodologies for Solutions Other Approaches Other applications involving non standard geometries and equipment, applications with moving boundaries (ie. blenders, augers etc.), transfer chutes require alternative approaches Physical modelling Discrete Element Modelling (DEM) 15

16 Methodologies for Solutions Physical Modelling Useful for complex systems approaching the boundary of the continuum models and bench scale tests Validity of the scale-up depends on utilizing underlying theory of solids flow Modelling work needs to be based on material characterisation 16

17 Methodologies for Solutions DEM DEM is rapidly developing in both its theories and computational speed but still in its infancy DEM becoming useful technology for Transfer chute design Situations where large scale, parametric experimental studies are difficult to perform or cost prohibitive *Not everything can be reliably modelled with DEM 17

18 Methodologies for Solutions DEM Limits Computing time limits the number of particles Various particle shapes can be modelled DEM model must be calibrated Physical properties Coefficient of sliding friction Angle of internal friction Particle density Boundary conditions Initial velocity Chute geometry 18

19 Methodologies for Solutions DEM Various particle shapes can be modeled SCIENCE ENGINEERING DESIGN 19

20 Methodologies for Solutions DEM SCIENCE ENGINEERING DESIGN 20

21 Methodologies for Solutions DEM SCIENCE ENGINEERING DESIGN 21

22 Conclusion Increasing throughput and/or changing the material without analysis can effect reliability of the system Determining if throughput of existing system can be successfully increased or if a new/changed material will flow through existing system requires evaluation to determine if/where bottlenecks may occur It is essential for continued reliability that proper analysis be performed and if the evaluation results in a potential bottleneck then new or modified equipment may be required. 22

23 In order to correctly identify bottlenecks Flow properties measurements are necessary to match material to system Proper analysis of system using appropriate methodologies: Continuum Model Conclusion Physical Modelling (when applicable) Discrete Element Modelling (when applicable) Properly evaluate and consider equipment 23

24 De-bottlenecking Iron Ore Transportation From Mine to Plant Questions? Corin Holmes Project Engineer Perth Western Australia