Technical Market Support

Trace Element Deportment in Combustion Processes

Technical Market Support » Thermal Coal

Published: March 07Project Number: C10057

Get ReportAuthor: MI Attalla, S Morgan, Ken Riley, G Bryant, Peter Nelson | CCSD, CSIRO Energy Technology, University of Newcastle, Macquarie University

Coal combustion is an important anthropogenic source of semi-volatile trace elements such as As, Hg, Cd, Se, Pb and Zn to the environment. These emissions are of significance because of potential environmental impacts on human and ecosystem health.

These metals are known to be volatile to some extent in the hot zone of combustion furnaces and to heterogeneously condense on to available surfaces such as ash particles in cooler zones downstream in the combustion process. Due to their relatively large surface area, fine ash particles can be preferentially enriched in trace metals. Depending on the trace metals deposition mechanism, different enrichment patterns can be observed. An understanding of the mechanism and factors that influence the partitioning of the trace metals between the different product streams of the combustion process is an important step in predicting and mitigating the release of these elements into the environment.

This project is a component of a larger CCSD program to develop a model to predict the vaporisation and subsequent partitioning of trace metals during the combustion of Australian coals, based on theoretical thermodynamic equilibrium, theoretical trace element vaporisation, experimental data and data correlation.

The main components of the ACARP project are:
  1. Bench scale combustion and pyrolysis experiments on specific coals at different oxygen concentrations.
  2. Summarise the experimental program by defining the coal and mineral character determining trace element partitioning to gas and particulate phases, and establish any impact of the combustion conditions.

Small-scale experiments were conducted in a laminar flow drop tube furnace on several Australian coals under various combustion and pyrolysis conditions. The coals used in this investigation were sourced from the CRC coal bank and represent a broad range of trace element and chemical compositions. All ash and aerosol products were analysed for the target trace metals by ICP-MS and the degree of trace metal enrichment was determined. Calcium-metal and metal-metal correlations were examined to determine the extent of these interactions and their impact on trace metal volatility.

The following observations can be made from the experimental results:
  1. Mercury was found to be highly volatile in all coals, with large concentrations appearing in the sub-micron and aerosol size fractions. A strong correlation was also observed between levels of "unburnt carbon" in the "bottom" ash or char and mercury retention in the coarse material (> 30 micron).
  2. The proportion of selenium found in the gas phase and in the submicron ash fell in the range of 60 to 80 % of the coal's starting selenium content.
  3. The other trace elements showed a broad range of partitioning to the submicron material, eg lead (10 to 90%), cadmium (0 to 70%) and nickel (0 to 50%). The trace element partitioning trends observed in this study are consistent with partitioning information obtained on US coals.
  4. Arsenic - calcium interaction appears to play an important role in the heterogenous transformation of arsenic from the vapour phase to the submicron particles, which is consistent with US studies. However, contrary to some work reported overseas (Seames, 2000), no other correlation between calcium and the trace elements studied were observed.
  5. The application of an air column for the preparation of "ash rich" and "ash depleted" coal fractions proved successful. Analysis of the fractionated coals revealed selective enrichment and depletion for some of the trace elements, notably mercury and selenium. This result may indicate a strong mineral association for these elements.
  6. Determination of "modes of occurrence" of the trace metals in the feed coals will be undertaken as part of the ongoing CCSD program. Once established the "modes of occurrence" of the trace elements will be used to determine the impact this has on partitioning behaviour of the elements.


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

C29021Assessing The Impact Of Consecutive Night Shifts On Night-Time Alertness, Daytime Sleep And Timing Of The Circadian System

In the Australian coal mining industry, most guidelines for managing...

C33037Quantifying Recharge To Groundwater Systems In The NSW Coalfields (Sydney, Gunnedah And Gloucester Basins)

The purpose of this project was to estimate the rate of diffuse rec...

C26029Geological Controls On Fluorine And Phosphorus In Bowen Basin Coals

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

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