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Cobalt in Australian export thermal coals
An examination of cobalt in Australian export thermal coals intended for industrial, scientific and research audiences.
- 21 July 2010 | Updated 14 October 2011
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.
| Concentration of cobalt in: | mg/kg |
| Australian export coals | 1 - 12 (4) # |
| Other internationally traded coals | 1 - 21 (5) # |
| Earth's crust | 25 |
| Earth's shales | 20 |
| # values in parentheses are averages | |
Cobalt has been identified as a Hazardous Air Pollutant (HAP) by environmental authorities.
Modes of occurrence
There is a very high uncertainty about the occurrence of cobalt in bituminous coals. It is associated with both the mineral matter (sulfides and/or clays) and organic matter.
Behaviour during combustion
Cobalt is slightly volatile and condenses on the fly ash particles. It may be 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, cobalt and compounds registers 1.0
- for the NPI environmental of 0-3, cobalt and compounds registers 2.
Cobalt is low in coal, and it is unlikely to have adverse environmental or health impacts.
Analytical methods
There are a number of Standard Methods for determining cobalt 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.
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 and Graphite Furnace Atomic Absorption Spectrometries.
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Fast facts
- Trace elements in coals may be associated with specific minerals or with organic 'coaly' matter
- There is a very high uncertainty about the occurrence of cobalt in bituminous coals
- Cobalt is associated with both the mineral matter (sulfides and/or clays) and organic matter
