Development of a Standard Operating Procedure for Analysis of Ammonia Concentrations in Coal Fly Ash.

摘要

Research was performed to support the development and recommendation of a standard operating procedure (SOP) for analyzing the ammonia content in fly ash intended for use in concrete. A review of existing ash producers found that several different analytical approaches are currently in use. Preliminary research involved examining both ammonia extraction and analysis techniques. An assessment of accuracy, precision, cost, and test duration was conducted for three test methods (salicylate color disc, ion-selective electrode, and gas detection tubes). The research team is recommending a standard operating procedure (SOP) utilizing a methodology involving the use of gas detection tubes to measure the headspace concentration of liberated ammonia gas above a mixed fly ash slurry in a closed flask. The measured gas phase concentration of ammonia in the flask headspace is then related to the amount of ammonia in the fly ash which was sampled. This method was selected as a preferred procedure because of higher accuracy and precision, consistent results, appropriate test duration, ease of use, and practical running costs. This SOP was beta tested at an ash producing facility in central Florida, and the method was then refined to address facility operator comments.