Technical Market Support » Thermal Coal
Increasing concern on the environmental impact of electricity generation from coal-fired power plants has focussed greater attention on the levels of trace elements in thermal coals. This has been mainly due to current and proposed legislation in may countries which places limits on the discharge, to the atmosphere, of trace elements known to be detrimental to health. There are also concerns relating to the fate and impact of trace elements in waste ash. As a consequence of this, there is now an increasing need for producers of export thermal coals to provide more reliable and accurate data on the levels of key environmental trace elements. A major problem with the specification of the levels of trace elements n coal is the lack of reliable and accurate standard methods. Methods currently available have been shown to be inadequate for specifying the concentrations of trace elements of environmental significance at the levels normally present in product coals. The main reason is that current standard methods were based on analytical techniques which lacked the necessary sensitivity. For many of the more important trace elements, no standard methods exist. The development of new methods for determining trace elements of environmental concern is therefore needed. The methods should be based on modern techniques and have the necessary sensitivity to reliably and accurately specify the levels of all key environmental trace elements.
The aim of this project was to develop new methods which would be adequate to reliably and accurately determine all environmental trace elements. The methods were to be based on modern instrumental techniques taking advantage of their high sensitivity and cost effectiveness.
A major consideration was that they be suitable for use in commercial laboratories and, where possible, be ultimately accepted as new standard methods. Where most sophisticated techniques were required for some trace elements, methods based on these techniques would be developed.
New reliable and accurate methods, based on modern instrumental techniques, were developed for determining all trace elements of environmental significance at the levels normally present in Australian export thermal coals.
The elements included in these methods are arsenic, antimony, beryllium, boron, copper, chromium, cobalt, cadmium, chlorine, lead, manganese, nickel, selenium, thorium, uranium, vanadium and zinc.
Two of the methods covering all the elements with the exception of antimony, cadmium, chlorine, uranium and thorium were based on techniques available in commercial laboratories. It is intended to propose these methods as new Australian standard methods after necessary validation trials.
Other methods developed for antimony, cadmium, chlorine, uranium, and thorium were based on more sophisticated techniques not normally available in commercial laboratories.
These new methods will provide the necessary sensitivity to accurately specify trace elements levels in export thermal coals and lead to better quality assurance in the marketing of thermal coals.
It has been shown that current standard methods for trace elements of environmental significance are inadequate to specify the level normally present in Australian thermal coals.
This was clearly evident from the results of inter-laboratory comparison in which laboratories generally preferred the use of in-house methods.
In some cases even these in-house methods proved unsatisfactory. The fact that standard methods were not generally used is evidence to suggest that these methods are assessed by commercial laboratories as being inadequate.
It is noteworthy that the results obtained by some os the laboratories using standard methods were inadequate and, in fact, worse than those using in-house methods.
This problem has been addressed in this project by the development of new methods based on modern techniques, which are accurate and reliable. Of most importance is the fact that these new methods have the necessary sensitivity to reliably specify the concentrations of all trace elements of environmental significance at the levels normally present in Australian export thermal coals.
The development of new methods was carried out in collaboration and consultation with commercial laboratories in order to achieve a consensus for application in commercial laboratories. This process was considered essential for the future adoption of these methods as standards for the industry.
It was achieved through the Standards Australia Committee MN1/1 Working Group on Trace Elements consisting of representatives of all participating laboratories.
While it is conceded that the methods based on ICPMS, XRD and PIGME may not be available to some commercial laboratories because of the sophisticated instrumentation require, they never-the-less provide the means for determining some the key trace elements not amenable to analysis by the more conventional techniques.
These methods are however available in the Division's Lucas Heights Laboratory which maintains a commercial service to coal superintending laboratories.
This project has addressed a concern in the coal industry relating to the specification of trace elements in export thermal coals. The adoption of the new methods will provide the necessary quality assurance of our exports. This is seen as a major benefit in maintaining Australia's position as the world's largest exporter of coal.