The amount of casthouse dross produced depends on the quantity of bath contained in the metal, the amount of aluminum fluoride (AIF3) added to the latter, operations in the melting oven and the quantity of value-added products being produced.
Recycling dross traditionally involves sending it to a supplier that can extract the metal and return it to the plant for reintroduction into the smelting process (recovery rate of 50-60%). The remaining material is considered either a waste product that must be disposed of or a by-product to be valorized.
An Alcoa technical group made up of experts from each plant in the region, as well as professionals from the Centre of Excellence, is currently sharing best internal practices on dross reduction and recycling. Following trials conducted in 2011, implementation of these best practices began gradually in 2012. Approximately 15% of the dross produced at the Deschambault Smelter and 38% of that produced at the Baie-Comeau Smelter were recycled in house. The recycling of pure metal dross was prioritized since it is an easier program to put in place.
Note: The quantities of casthouse dross produced and recycled in Baie-Comeau in 2011 were adjusted to account for the amount of dross recycled in house.