Results from Fluoride Emission Reduction Projects in Alcoa Baie-Comeau

In 2012, Alcoa started an initiative to sustain the operation at the Baie-Comeau aluminum smelter in provision of creeping the amperage of potlines by more than 7%. As part of this initiative, solutions needed to be identified to stabilize the operation of the four Gas Treatment Centers (GTCs) and ensure compliance with a new emission limit for total fluorides (TF) of 0.65 kg TF/ton Al. The project is an engineering alliance project jointly executed by a team of Alcoa and Hatch specialists. The first stage was to identify which tools were available to the smelter to reduce their emissions. The impact and costs were evaluated after which a strategy was formulated. Following Alcoa procedures for approvals, three improvement projects were funded. These were (1) the installation of extended surface filter bags in the GTCs, (2) new fresh alumina GTC distribution systems, and (3) a refurbishment program for the GTC collector ducts. This paper highlights the process for developing the strategy to lower emissions and how the three individual projects were executed with one common goal. The paper concludes with the outcomes and the overall results achieved in the fluoride emission reduction.