April 18, 2020
A Fresh Look at Waste
Operators at the facility in Washington state in the U.S. have improved processes in the rod shop, where residual crust is cleaned from used anodes. The metal rod inserted into the anode is also removed in the shop. Both operations result in fine particles that, until recently, were gathered by the same dust-collection system and then landfilled.
A process change along with new equipment enabled the dust streams to be separated, allowing the crust fines to be reused in the smelting process and the metal fines to be sold for use in other industries. The change diverts 1,500 metric tons of waste from the landfill annually.
A second project resulted in reclassifying sludge from Intalco’s onsite wastewater treatment plant from hazardous to non-hazardous, opening the door to reuse possibilities.
The sludge was designated as hazardous since the plant treated the leachate from the site’s onsite landfills, which contain a hazardous waste known as spent potlining. The landfills were closed in 1990 and capped in 2011, but the leak detection system—intended to determine if leachate was breaking through containment liners—was receiving fluid. This was despite the leachate collection system being dry, which indicated no leachate was present from the closed landfill.
A study conducted by external experts found that the fluid was rainwater, which never contacted the spent potlining. This meant the wastewater treatment plant was not receiving any landfill leachate. As a result, the state reclassified the wastewater sludge as non-hazardous in 2019. Intalco has started exploring possibilities for the sludge’s reuse.