ACARP ACARP ACARP ACARP
Coal Preparation

Fine Coal Classification

Coal Preparation » Fine Coal

Published: February 99Project Number: C3084

Get ReportAuthor: Bruce Firth, Michael O'Brien, Darren Edward, Chris Clarkson | CSIRO Energy Technology, C Clarkson & Associates

This project formed part of a major program under the CMTE, with the overall objective of enhancing coal recovery by developing new or improved technology for fine coal classification.

The project had the following components.

1. Baseline testing at three coal preparation plants to define the actual performance of size classification unit operations under typical operational conditions. These were selected on the basis of differing types of plant feed and the fine coal circuits employed.
2. Best practice data was obtained from equipment suppliers, available research information and other sources.
3. A number of recently developed commercial size classification devices were made available to the project. These units were evaluated in the pilot facility at QCAT under controlled conditions and a detailed understanding of their capability was obtained. This information is available for a comprehensive comparison of potential options for classification.
4. The most promising option in terms of selection of unit operations and circuit configuration has been investigated at a realistic scale in an operating plant.

Hydrocyclones provide a cost effective method of classification, but two problems with this device were identified:

  • ultra-fine particles report with the oversize flowstream in proportion to the water split
  • coarse coal particles report to the undersize flowstream due to the adverse effect of the wide range of particle densities found in fine coal feeds

Approaches to overcome the first problem such as using two cyclones in series tend to exacerbate the density effect problem and result in unacceptable loss of coarser coal particles. Pilot plant investigations and computer simulations have identified the 'Three Stage Counter Current Cyclone Circuit' (CCC) as the best option for overcoming these two problems.

Three alternative separation units were tested at the QCAT pilot plant.

  1. Whirlsizer - Not suitable for classification of fine coal
  2. Varisieve - Technically superior to the hydrocyclone but requires high screen area and regular maintenance
  3. Water Injected Cyclone - Shown to be able to significantly reduce the amount of ultrafines, but leads to a large increase in the separation size of low density material such as coal. It may also worsen the density effect.

A 'Three Stage Counter Current Cyclone Circuit' was constructed with commercial sized cyclones (350 and 250mm diameter), and a detailed investigation was carried out at one of Australia's largest export coal mines. This novel circuit has achieved considerable improvement in classification efficiency when compared with a conventional single cyclone. The amount of ultrafine particles in the oversize flowstream was reduced by over fifty percent and this also led to a reduction in the amount of very fine sized pyrite particles in this flowstream. The size of separation was similar (0.09 compared with 0.10mm), but the sharpness of the partition curve was increased with the CCC circuit and the loss of clean coal in the minus 0.250 plus 0.063 size fraction reduced by about 40%.

All three stages can be implemented with only a single pumping station and gravity feeding of subsequent units if there is sufficient height in the plant, hence maintaining simplicity of the plant circuit.

Underground

Health and safety, productivity and environment initiatives.

Underground

Open Cut

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

Recently Completed Projects

C19024Establishing Ecologically Sustainable Mine Water Release Criteria In Seasonally Flowing Streams

Extreme rainfall conditions in the Fitzroy Catchment over an approxi...

C25030Coal Mine Open Pit Final Void Closure And Relinquishment - Addressing Uncertainty In Coal Mine Environmental Planning

This report addresses uncertainties faced by coal mine operators whe...

C27046Estimation Of True Deformation Vector From Slope Radar Monitoring

Slope deformation radar monitors are now widely used in open cut coa...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C27004Improving Coal Flotation With Oscillatory Air Supply

This report provides detailed information on coal flotation with os...

C25018Improving Solids Recovery And Moisture Reduction In Ultrafine Coal Dewatering

This report provides detailed information on fine coal dewatering in...

C27028Lab Froth Flotation Testing Guide With Coal Quality

Correct outcomes from laboratory froth flotation testing in coal bor...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C26039Nanoporosity In Cokes: Their Origin, Control And Influence On CO2 Reactivity

This project using the outcomes of previous project C24060, examine...

C28063A Comprehensive Technical Review Of High-Efficiency Low-Emission (HELE) Pulverised Coal Combustion Technologies For Power Generation

Research and development has been undertaken worldwide to realise co...

C28064Carbon Structure Transformation During Coking Of Australian Coking Coals: Better Understanding The Coke Formation

Carbon structures of coke that are formed during the plastic layer a...

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) - Phase 2 Demonstration In A Packed Bed Reactor

An alternative approach to high temperature oxidation of ventilation...

C26004CFD Modelling Of Reverse Thermal Oxidisers For VAM Abatement - CFD Modelling Of Fixed-Bed RTO Devices

The project is part of a larger multi‐phase program of study a...

C27058Technological Assessment Of A Recycle Reactor For VAM Abatement

Underground coal mining emits high volumes of methane, diluted in ve...

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

NERDDC

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

NERDDC