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Antimony in Australian export thermal coals

An examination of antimony in Australian export thermal coals intended for industrial, scientific and research audiences.

• 21 July 2010 | Updated 14 October 2011

• Modes of occurrence
• Behaviour during combustion
• Health and environmental effects
• Analytical methods

Trace elements in coals may be associated with specific minerals or with organic 'coaly' matter.

The sources of trace elements include biological material (plants, algae and bacteria) that is the precursor of the coaly material, water in the peat swamp and mineralogical material washed or blown into the swamp.

Antimony has been identified as a Hazardous Air Pollutant (HAP) by environmental authorities.

Modes of occurrence

There is a high level of uncertainty about the occurrence of antimony in bituminous coals. It is thought to be associated with sulfide minerals and the organic matter.

Behaviour during combustion

Antimony is volatile and condenses on the fly ash particles. It is enriched in the finer particles; a small percentage of these fine particles are emitted to the atmosphere from modern power stations. 

Health and environmental effects

On the spectrums:

• for the NPI health hazard of 0–3, antimony and compounds registers 1
• for the NPI environmental of 0-3, antimony and compounds registers 1.3.

There are no reports of adverse environmental impacts from the antimony compounds present in coal and coal ash.

Analytical methods

There are a number of Standard Methods for determining antimony in coal.

AS 1038.10.0, Australian Standard, Coal and coke - Analysis and testing - Part 10.0: Determination of trace elements – Guide to the determination of trace elements.

AS 1038.10.2 Australian Standard, Coal and coke – Analysis and testing – Part 10.2: Determination of arsenic, antimony and selenium – Hydride generation method.

ASTM D4606-95(2000) Standard Test Method for Determination of Arsenic and Selenium in Coal by the Hydride Generation/Atomic Absorption Method.
 
ASTM D6357-00a Test Methods for Determination of Trace Elements in Coal, Coke, & Combustion Residues from Coal Utilization Processes by Inductively Coupled Plasma Atomic Emission, Inductively Coupled Plasma Mass, & Graphite Furnace Atomic Absorption Spectrometries.

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