Coal Preparation

Commercial Laboratory Scale Float-Sink Testing Using Stabilised Suspension

Coal Preparation » Gravity Separation

Published: May 12Project Number: C18038

Get ReportAuthor: Shenggen Hu and Andrew Taylor | CSIRO

The objective of this project was to carry out commercial lab scale float-sink testing using the stabilised suspension of submicron zirconium dioxide developed in ACARP project C15057.


A float-sink separator has been developed for carrying out float-sink testing using opaque suspensions. In this separator, floats can be quickly and easily separated from sinks by using a separation plate without causing back-mixing.


To compare the washability data from the two methods when the number of repeated tests or the mass of sample is increased, float-sink testing on six parallel samples was carried out using both stabilised suspensions and organic heavy liquids. Variations among washability curves can be reduced to an acceptable level when the mass of combined sub-samples satisfies the rule on minimum sample masses as specified in Australian Standard AS 4156.1. The combined washability curve of six sub-samples obtained from the stabilized suspension is almost identical to that from organic heavy liquids except in the density range lower than 1.4. The small difference was caused by water filling the pore structure of coal particles and also the different drying methods used.


Water can penetrates more pore spaces than organic liquids due to its smaller molecular size, leading to a slightly higher apparent relative particle density, particularly for coals having a RD less than 1.3. Coals with a lower RD are more porous than those with a higher RD.


As a significant degree of uncertainty was involved in air dried masses due to uncontrolled air temperature, humidity and air flowrate, the mass of floats and sinks was determined after drying in an oven at a temperature between 1010C to 105 0C for 24 hours. Consequently, washability results obtained by stabilised suspensions using thermal drying have a relatively high precision.


Although the washability data obtained from aqueous suspensions would better reflect what occurs in coal preparation plants, both stabilised suspension and organic heavy liquids would give equally good predictions of process efficiencies, yields and separation cutpoints as the difference in washability curves occurs only at the lowest end of density range. In term of the evaluation of coal resources, the accuracy in the determination of the amount of coal in situ using the washability data obtained from aqueous suspensions will depend on the moisture content of the coal in situ. For dry coals, the amount of coal with a relative density lower than 1.3 would be slightly underestimated due to the reason that the apparent relative density of porous coal is higher in aqueous suspensions than that in organic liquids. For the prediction of yield, there should be no significant difference between the two methods.


Operating procedures for preparing stabilised suspensions and carrying out float-sink testing using the suspension were developed and validated.


Health and safety, productivity and environment initiatives.

Recently Completed Projects

C27039True Triaxial Strength Of Coal Measure Rocks And Its Impact On Roadway Stability And Coal Burst Assessment

Rocks in the ground are subject to a range of stresses. The stresses...

C3063Underground Vehicle Design Standards And Statutory Implications

The Australian underground diesel vehicle fleet has evolved since di...

C3064Conveyor Belting And Lagging Shear Characteristics - Drive Drum Slip

The primary aim of this project was to investigate the relationsh...


Open Cut

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

Recently Completed Projects

C26029Geological Controls On Fluorine And Phosphorus In Bowen Basin Coals

Increasing global restrictions on fluorine in product coal prompted ...

C28033Raw Ash To Yield Relationships

Correct outcomes in yield predictions for product ash from coal bore...

C27038Establishing Self-Sustaining And Recognisable Ecological Mine Rehabilitation

In recent years an increasing interest has been placed on mining ope...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C27064Dry Beneficiation Using FGX And X-Ray Sorters

Conventional dry processing methods engage a single beneficiation de...

C26010Multi-Sloped Screening Efficiency With Changing Strokes, Frequencies, Feed Solids And Feed Rates-Pilot Plant Study

Optimising multi-sloped screens is often described as an art and the...

C28059Impact Of Water Quality In Coal Handling And Preparations Plants

The objective of this project was to deliver a concise reference do...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C23052Novel Stone Dust Looping Process For Ventilation Air Methane Abatement

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

C27054Optimisation Of A Thermal Flow Reversal Reactor For Ventilation Air Methane Mitigation

Ventilation air methane (VAM) generally accounts for 50-85% of the t...

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...

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