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Addition of briquettes to supplement the anode.
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2008 — Environment
The ABS approach to better environmental compliance
New, stricter regulations will be going into effect in 2010 for polycyclic aromatic hydrocarbons (PAH) emissions – contaminants produced during the combustion of organic matter. In anticipation of these harsher requirements and to ensure compliance, the Baie-Comeau Smelter applied ABS (Alcoa Business Systems) tools such as visual management and the standardization of work methods to reduce emissions at its Söderberg potrooms.
In 2005, the smelter was emitting an average of 0.28 kilograms of PAH per metric ton of aluminum produced (kg/mt Al). The new limit will be 0.20 kg/mt Al, requiring a reduction of at least 28%.
“We had to adopt new and original operating methods to be able to comply with the regulations once they come into effect in 2010,” explained Denys Bérubé, Anode Technical Coordinator at the smelter. “This was excellent motivation to work together to lower our PAH emissions.”
In 2006, the teams began to focus on the two activities that generate the most PAH emissions, namely changing the anode studs and the adequate distribution of briquettes at the top of the anodes.
Three of the 54 steel studs at Baie-Comeau’s Söderberg pots must be changed every day. This operation used to take an average of 20 minutes. One of the reduction solutions is to complete the operation in only 10 minutes. The smelter implemented a standardized work method, supported by a performance management system that enables the monitoring of the results of each operator.
The addition of briquettes is done from the top of the anodes, which compensates for the part of the anode that is consumed during the normal process of electrolysis. The briquettes also filter PAH emissions during the continued baking of the anode. These emissions increase when there are not enough briquettes.
To ensure that each anode received an adequate amount of briquettes, we created a visual progress chart to plan briquette distribution and ensure proper monitoring of the activity. Problem-solving mechanisms enable workers in every position to quickly take action in the event of a problem.
At the end of 2006, the Baie-Comeau Smelter was emitting an average of 0.18 kg/mt Al of PAH, less than will be required by the new regulations. Emissions were 0.20 kg/mt Al in 2007, which confirms the smelter’s improved performance.