Impact of Operational Practices and Cell Hooding on Total Fluoride Emissions in the Aluminium Smelter Plant of Aluar

摘要

EPA Method 14A is one of the most widely used methods for measurement of total fluoride (gaseous and particulate phase expressed as Ft) emissions through roof monitors in aluminium primary smelters. In order to obtain the Ft concentration emitted from the potroom, several cassette arrangements are placed in predetermined locations and later removed from the roof monitor for the analysis of each run.Because Aluar operates a total of 8 potrooms and this kind of environmental testing is costly and elaborate, an alternative approach is required to keep monitoring the emissions on a daily basis. A robust and cost effective option is to identify those pots that are missing at least one hood simultaneously due to operational and/or maintenance practises.This paper presents the development of tests with the purpose to find a correlation between Ft concentration measured with EPA method 14A and the sum of pots with at least one hood opened, as well as to establish a theoretical factor to relate the amount of pots in such condition to specific emissions in potrooms where we use the original Aluar type PFPB end-to-end cells. It was estimated that during normal operation an increase of 0.03 kg of Ft per (metric) ton of aluminium produced (equivalent to 0.36 kg Ft per hour) is added to the current Ft emission per pot with one hood opened.