Nashville, Tennessee, 5 – 7 May 2015
This interesting conference was organised by the American Coal Ash Association (ACAA) and the Center for Applied Energy Research (CAER), University of Kentucky and I attended to present a paper and as a delegate.
Papers were presented on such diverse topics as the beneficial use of coal construction products (CCP’s) in cement and concrete, regulations, extraction of rare earth elements (REE’s) and agricultural uses. Over 800 delegates attended, with many visitors from outside the USA.
Several papers stressed the great potential of extracting fly ash from stockpiles and lagoons, or ponds in US terminology, and processing the material to obtain products for the construction industry. This recovery and beneficial use of fly ash contributes to sustainable construction and would help to maintain the availability of fly ash. A readily available complementary source of fly ash would help to reduce seasonal supply variability.
The Environmental Protection Agency (EPA) has introduced new regulations to control storage and disposal of CCP’s in the USA. These materials will be controlled under “subtitle D” of the Resource Conservation and Recovery Act (RCRA) and are considered non-hazardous. Rules exist to ensure the structural stability of storage facilities such as stockpiles and lagoons, with inspection regimes and corrective actions detailed. Groundwater monitoring procedures are also specified. This approach has the advantage of protecting local communities and the environment, without classifying CCP’s as hazardous which would reduce significantly the beneficial use of coal ashes in the USA.
A more unusual application for fly ash considered at the conference was as a source of industrial minerals. This ranged from aluminium extraction to obtaining REE’s and other scarce strategic metals. For example, neodymium and dysprosium are critical for the permanent magnets which are used in many modern electronic devices. Within particular ashes, RRE’s may be at high enough concentrations to make extraction worthwhile.
Robert Carroll – Technical Director UKQAA
20 May 2015