Coal Preparation

Effect of Flotation Water Chemistry on Coal Chemistry, Fluidity and Coke Quality

Coal Preparation » Process Control

Published: March 18Project Number: C25011

Get ReportAuthor: Ghislain Bournival, Feng Zhang Noel Lambert, Sushil Gupta, Pramod Koshy and Seher Ata | The University of New South Wales

In an effort to minimise fresh water use, a number of Australian coal preparation plants use underground water or recycled water. The use of alternative water sources in coal preparation, especially in flotation, has significant effects on flotation and coke characteristics since these water sources contain many dissolved compounds, both inorganic as well as organic, which radically alter the chemistry of the system. Significant work has been carried out on the role of alternative water sources on flotation performance. However no study has looked into the effect of the use of recycled water on the caking properties (Gieseler plastometry) of coals in preparation plants using recycled water. Whilst some plants have observed a reduction in maximum fluidity, the cause was unknown. This study investigated the effect of recycled water on the caking properties of coals.

Experiments were conducted with a series of inorganic electrolytes which includes: Na2CO3, K2SO4, Na2SO4, CaCO3, CaCl2, and MgCl2 as well as process water. The coal samples were either left to oxidise in a well controlled environment or placed in an inert atmosphere to limit oxidation. The changes occurring on the coals were evaluated by Gieseler plastometry and the surface was characterised by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) equipped with an energy dispersive x-ray spectrometer (EDS).

The reduction in fluidity observed due to the use of recycled water may be caused by the oxidation of the coal. The oxidation may be accelerated by the presence of inorganic electrolytes, which were shown by XPS to produce carbon oxides. However, the major effect, which has been observed to reduce fluidity, was from the concentration of inorganic electrolytes in the water. It was shown that even after dewatering a substantially large amount of inorganic electrolytes remains in the water with the coal as evidenced by SEM-EDS. These ions precipitate in the form of solid salts on the surface of the coal particles and affect the caking properties of the coal. De-watering a 0.1 M solution (which is found in coal preparation plants) at 30 % water (w/w) in coal leaves a 2 % (w/w) of salt in the coal. Such amount of salt was sufficient to reduce the maximum fluidity of the coal by approximately 84%. Salts have been known for their de-caking properties. It is speculated that they act as cross-linking agents and produce large macromolecular structures thus combining free radicals which are produced during pyrolysis. These structures are believed to reduce the fluidity of the coal.


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