Coal Preparation

Improved Centrifuge Basket Performance

Coal Preparation » Dewatering

Published: June 06Project Number: C12054

Get ReportAuthor: Glenn Hart, Michael O'Brien, Bruce Firth | CSIRO

Experimental work at Coppabella by Sedgman suggested that a moisture reduction could be obtained via a reduction in the basket speed with a commensurate increase in basket life.  This finding raised the issue of our lack of understanding of :

  • The importance of the method of placing the coarse coal feed into the centrifuge,
  • Bringing this feed coal up to the rotational speed of the basket, and
  • The movement of the bed of coal over the basket. 

The objective of the project was to improve the understanding of dewatering performance and wear life of a basket centrifuge via optimal presentation of the coarse coal to the basket, its subsequent movement over the screen and the impact of the centrifugal force being applied.

The project required the collaboration of staff from CSIRO, Sedgman Pty Ltd and Ludowici Mineral Processing Equipment Pty Ltd.

The system under investigation can be described as :

  • Coal, with a size range of -50+0.5mm, falling from a drain and rinse screen into a pipe connected to a centrifuge feed chute.
  • The coal then moves through the chute at high velocity (possibly up to 8 m/sec).
  • It impacts the distribution plate at the back of the centrifuge at high speed where it should be redirected to the basket wall.
  • At this point the coal forms a bed on the screen.
  • The angle of the basket should be less than the angle of friction, and
  • the particles are moved over the basket assisted by axial vibration which effectively causes some fluidisation of the particle bed. 

The important control factors are :

  • There is sufficient centrifugal acceleration (Zg) to obtain an acceptable dewatering outcome.
  • The particles are subjected to that force for sufficient time for the film drainage to take place.

The work program was split between two aspects :

  • Controlling and modifying the movement of coal through the centrifuge. This meant examining and controlling the delivery of coal on to the basket via the chute, and the movement of coal across the basket before discharge.
  • Observing and measuring the movement of material (coal) through the chute and centrifuge and the moisture content of the coal.

The work program was further divided into a laboratory and full scale programs.

One of the main aspects of the laboratory program was the development of a novel chute design to improve the presentation of the coal to the basket. The best design at this scale was the use of a channel rather than a rounded pipe section, curved at the end to aid in the redirection of the feed and tilting the channel end to aid in the distribution of the feed across the chute.

For the plant investigation, a basket with full length accelerator bars was constructed to accelerate the coal up to the basket speed in as short a time as possible and to help minimise bed slippage along the full length of the basket.

The following conclusions were made from the results :

  • The moisture contents were higher than expected due to the centrifuge being lightly loaded. This is at odds with conventional thinking which suggests that a lightly loaded centrifuge should perform best due to unhindered dewatering of thin beds. Analysis of particle movement across the basket suggests that the particles have a low kinetic friction factor which means that they are fluidised and exit the basket quickly, reducing residence time in the basket. Optimisation of the centrifuge for lower feed rates may improve the dewatering performance of the centrifuge, optimisation may include lowering the vibration amplitude or adding a discharge lip to the basket, both will increase the residence time of the coal in the centrifuge.
  • As the centrifuge speed is increased, the increased centrifugal acceleration (Zg) appears to be balanced by the decreased residence time and reduced bed depth for the normal chute with minimal impact on the moisture content. Although the increased force acting on the water surrounding the particle drives it off faster, unfortunately, there is insufficient time to effectively remove it from the particle.
  • The residence time does decrease with increasing centrifugal acceleration (Zg) for baskets fitted with either the normal or long accelerator bars. Interestingly, the basket fitted with long accelerator bars had lower residence times and slightly higher moisture compared to the conventional basket, at least for the larger particle sizes.
  • The slightly higher product moisture for the basket with long accelerator bars is related to the reduced residence time. Optimisation by reducing the amplitude of the basket vibration may also reduce this moisture.
  • The curved chute resulted in higher moisture values than the normal chute; it is believed that the new method of entry results in a more fluidised bed with a lower kinetic friction factor, thus reducing the residence time.
  • The curved chute had similar moistures for both the normal basket and the basket fitted with long accelerator bars except for the higher Zg on the normal basket. The high moisture value is linked with the rapid movement of the coal over the basket surface.
  • The main difference between the Coppabella investigation and this one at Morevale was the level of loading in the centrifuge and the significantly different bed depths.
  • It is suspected that bed depth increases the kinetic friction factor and the balance between the impacts of centrifugal acceleration (Zg)


Health and safety, productivity and environment initiatives.

Recently Completed Projects

C34019Longwall Bretby Cable Handling Monitoring With Fibre Optics

This project examined the potential of using fibre optic sensing tec...

C28028The Inclusion Of High Interest Native Plants In Mine Site Restoration Programs: Propagation, Translocation And Field Re-Introduction

This report synthesises over 10 years of ex situ and in si...

C27049Mine Machine Radar Sensor Integration

The aim of this project was to develop an integrated radar sensor an...


Open Cut

Safety, productivity and the right to operate are priorities for open cut mine research.

Recently Completed Projects

C34029Validation Of Laser Induced Breakdown Spectroscopy (LIBS) As A Rapidly Deployable Field Technology To Estimate Coal Quality

Rapid evaluation of a coal resource by in-situ characterisation dow...

C34028Guidelines For Assessment Of Geotechnically Safe And Stable Post-Mining Landforms

The purpose of this project was to develop a guidelines document as ...

C34016Elements In Coal – A Start-To-End Analysis

This project explores the fate and concentration potential of critical e...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C26016Determining The Benefits Of Online Thickener Underflow Rheology Measurements

The aim of this project is to determine how useful the rheology meas...

C33056Modelling And Control Of Classifying Cyclones

Hydrocyclones are one of the key technologies for the classification...

C28056Surface Alloying Of Centrifuge Baskets And Sieve Bends Screen Surfaces To Increase The Service Lifetime

The main objective of this project was to improve the wear resistanc...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C33066Washability And Distribution Of Sulfur And Trace Elements For Different Size And Density Fractions Of Raw Coals

Based on the hypothesis that the levels of sulfur and other toxic tr...

C34060In-Situ Investigation Of Coke Structure Formation Under Stamp Charged Coking Conditions

Stamp charged cokemaking has emerged as an effective technique to im...

C34062Improving The Classification Of Microstructure Distribution In Coke CT Images Using Deep Learning And Lineal Path Calculations

This project builds on a number of earlier projects that have helped...

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C28076Selective Absorption Of Methane By Ionic Liquids (SAMIL)

This third and final stage of this project was the culmination of a ...

C29069Low-Cost Catalyst Materials For Effective VAM Catalytic Oxidation

Application of ventilation air methane (VAM) thermal oxidiser requir...

C23052Novel Stone Dust Looping Process For Ventilation Air Methane Abatement

This multi‐phase project is concerned with the mitigation of m...

Mine Site Greenhouse Gas Mitigation

Low Emission Coal Use

Step-change technologies aimed at reducing greenhouse gas emissions.

Recently Completed Projects

C17060BGasification Of Australian Coals

Four Australian coals were trialled in the Siemens 5 MWth pilot scale ga...

C17060AOxyfuel Technology For Carbon Capture And Storage Critical Clean Coal Technology - Interim Support

The status of oxy-fuel technology for first-generation plant is indicate...

C18007Review Of Underground Coal Gasification

This report consists of a broad review of underground coal gasification,...

Low Emission Coal Use

Mining And The Community

The relationship between mines and the local community.

Recently Completed Projects

C16027Assessing Housing And Labour Market Impacts Of Mining Developments In Bowen Basin Communities

The focus of this ACARP-funded project has been to identify a number...

C22029Understanding And Managing Cumulative Impacts Of Coal Mining And Other Land Uses In Regions With Diversified Economies

The coal industry operates in the context of competing land-uses that sh...

C23016Approval And Planning Assessment Of Black Coal Mines In NSW And Qld: A Review Of Economic Assessment Techniques

This reports on issues surrounding economic assessment and analysis ...

Mining And The Community


National Energy Research,Development & Demonstration Council (NERDDC) reports - pre 1992.

Recently Completed Projects

1609-C1609Self Heating of Spoil Piles from Open Cut Coal Mines

Self Heating of Spoil Piles from Open Cut Coal Mines

1301-C1301Stress Control Methods for Optimised Development...

Stress Control Methods for Optimised Development and Extraction Operations

0033-C1356Commissioned Report: Australian Thermal Coals...

Commissioned Report: Australian Thermal Coals - An Industry Handbook