Exergoeconomic and exergoenvironmental analyses of a promising alumina extraction process from secondary aluminum dross in China

Abstract

Secondary aluminum dross (SAD), listed as a hazardous waste in China, has become a big bottleneck for aluminum industry under massive accumulation and tight regulations. In the dilemma of few industrial treatment cases, an alumina extraction process from SAD proposed by us has been proved a promising technological-feasible process. A coupled exergoeconomic and exergoenvironmental analysis was used to identify key consumption reduction opportunities and potential for economic or environmental improvement of this process. Results showed that Calcination had the lowest exergy efficiency (32.16 %), which required waste heat recovery. Alumina Dissolution and Evaporation and Concentration had high exergy destruction ratio, which is necessary to improve steam utilization efficiency. Furthermore, the relative cost difference of Calcination was the highest (208.75 %) with the greatest potential for economic benefit optimization. Except for Filtration and Drying and Grinding and Sieving, exergoeconomic factors were all below 30 %, which need to adjust non-energy investment cost or equipment structure. The units with low exergy efficiency also had high relative environmental impact difference, among which Calcination was the most significant (183.61 %). Finally, a sensitivity analysis was performed on the identified units with low economic or environmental benefits. This study provides multi-dimensional guidance for the sustainable design, process optimization and industrialization of SAD recovery processes.