Coal Preparation

Impact of Saline Water on Coal Flotation

Coal Preparation » Environmental Improvement

Published: October 05Project Number: C13051A

Get ReportAuthor: Philip Ofori, Bruce Firth, Graeme Jameson, G Franks, A Nguyen | CSIRO Energy Technology, University of Newcastle

This project has produced a handbook to assist plant operators to understand the implications of changes in water chemistry in the plant, particularly on flotation.
Large inventories of saline water are accumulating at some mine sites due to discharge restrictions. At the same time there is pressure on the importation of fresh water for use at mine sites. It makes sense to use the saline mine water for all duties and processes where detrimental effects are minimal or where there is beneficial impact on operations. One of the areas where saline water can be used is as process water in the coal preparation plant. The work detailed here is aimed at understanding the major impacts of saline water on coal flotation which is the process most likely to be significantly affected due to its dependence on surface chemistry to function effectively.

Experimental data from batch flotation tests in which no conventional reagent was added clearly showed that flotation recovery generally increases with increasing electrolyte concentration at least for the salts used in these experiments.  For the single salts studied, combustibles recoveries attained in the presence of MgSO4 were slightly higher than those of MgCl2 and CaCl2 and these salts in turn produced much higher flotation recoveries than NaCl at the same concentrations. This is consistent with zeta potential data. When the combustibles recovery data was examined in terms of ionic strength, the results for all the salts were much closer.

Flotation in mixtures of salts produced higher combustibles recoveries than in single salts at the same concentration. The implication is that lower concentrations of several salts as found in saline waters at minesites could produce enhanced flotation recoveries even when individual salts at those concentrations have only minor effect on coal combustibles recovery.

Flotation using conventional collector and frother in the presence of low concentrations of salts such as MgSO4 results in higher combustibles recovery than when the salt is absent. Conversely, lower concentrations of the collector may be required to attain the same combustibles recoveries when the water contains small concentrations of salts.

The flotation kinetics data also show increases in flotation rate with increasing salt concentration.

The concentrations at which maximum recovery is attained are different for the different coal samples. For two coals of similar rank, one was found to be more difficult to float in saline water than the other. Petrographic analysis of the coals showed that the dominant maceral in the more floatable coal was vitrinite and the difficult to float coal was dominated by inertinite. The differences in flotation response between these coals may be attributed to a lower response of inertinite to salt flotation.

Social and commercial requirements mean that many coal preparation plants will be forced to use saline water accumulated from the associated mining operations.  This investigation has identified potential opportunities to decrease the use of collector/frother in the flotation circuit by proactive use of a saline water mixture to optimise a flotation response, especially where divalent cations concentration is high.


Health and safety, productivity and environment initiatives.

Recently Completed Projects

C26061The Young’S Moduli, Poisson’S Ratios And Poroelastic Coefficients Of Coals

This report describes the measurement of coal (and rock) properties ...

C24015 Assessment Of Convergence Based Roof Support Design For Longwall Abutment Loads

The aim of Stage two of project C24015 was to develop a roof support...

C25072New Approaches To Mine Gas Analysis And Ratios

The spontaneous combustion of coal remains a hazard in underground c...


Open Cut

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

Recently Completed Projects

C26022Real-Time Prediction Of Coal Top Through Guided Borehole Radar Wave Imaging For Open Cut Blast-Hole Drilling

Damage to the tops of coal seams caused by incorrect blast stand-off...

C26027Using An Ecotoxicological Approach To Validate The DGT Technique For The Measurement Of Bioavailable Metal Concentrations

This project builds on the opportunity identified through Project C2...

C25039Prediction Of Long-Term Salt Generation From Coal Spoils

The release of salts from spoil piles has the potential to affect su...

Open Cut

Coal Preparation

Maximising throughput and yield while minimising costs and emissions.

Recently Completed Projects

C250083D Flotation Of Fine Particles

In this project a process for the continuous, selective agglomeratio...

C20052Full Scale Gravity - Desliming Using Cascading REFLUX Classifiers

Considerable quantities of fine coal are disposed of as part of the ...

C26007 Revised Dustiness And DEM Test Method (Update Of AS4156.6) Part 2:Preparation

In 2015 project C23054 investigated and reviewed the Australian Stan...

Coal Preparation

Technical Market Support

Market acceptance and emphasising the advantages of Australian coals.

Recently Completed Projects

C25045Stage Two - Assessment Of In Situ High-Temperature Strength Of Cokes

Stage I of this project established a reliable and repeatable proces...

C27003Review Of ACARP Research To Support Marketing Of Australian Thermal Coal

In this project, researchers pinpointed issues relating to the use o...

C25044Trace Elements In Coal; Status Of Test Methods In Use And Their Applicability


The key objectives of this stage...

Technical Market Support

Mine Site Greenhouse Gas Mitigation

Mitigating greenhouse gas emissions from the production of coal.

Recently Completed Projects

C27008Selective Absorption Of Methane By Ionic Liquids

The connection of a ventilation air methane (VAM) abatement plant di...

C24061Proof-Of-Concept Photocatalytic Destruction Of Methane For Coal Mining Fugitive Emissions Abatement

Australia's fugitive emissions in 2015 were 41 Mt CO2-e (representin...

C23052Novel Stone Dust Looping Process For Ventilation Air Methane Abatement - Phase 3

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