In the manufacture of aluminum, a carbon-based liner acts asthe cathode for the electrolysis process which reduces alumina toaluminum. This liner degrades during the production process, and theresultant waste, spent potliner(SPL), is defined as a listed (K088)hazardous waste. Approximately 110,000 metric tons/year of this hazardouswaste must be disposed of in the U.S. Vortec proposes to develop achemical process to remove the cyanides, fluorides and heavy metals fromthe SPL, leaving a material rich in carbon, alumina and silica. Theproposed chemical process will also allow for the separate recovery ofaluminum fluoride and heavy metals, as well as the destruction of thecyanides.During Phase I, Vortec will perform laboratory testing of the acidicextraction of cyanides, fluorides, and heavy metals from SPL and thedestruction of cyanides by ozonation. The testing will focus on theparameters which control the extraction and oxidation processes. Phase IIof the program will concentrate on the design, construction and testingos a laboratory-scale unit to verify the effectiveness of the proposedchemical process. The Phase II program will also develop a preliminarycommercial system design, and its life cycle cost.
