Life cycle assessment of the casting process with the addition of niobium from scrap

Abstract

Sustainability has become increasingly important, given the scenario of environmental degradation, and the industrial sector is significantly responsible for this adverse scenario. An important manufacturing process is casting, but it consumes many natural resources and generates waste, emitting pollutants and consuming much water and electricity. Thus, this work investigated the environmental impacts through life cycle assessment (LCA) arising from the gray cast iron casting process by adding niobium from scrap. Niobium improves molten material’s structure and mechanical properties, and it has been obtained from a company that separates it with a ballistic magnetic separator. A production model of 800 ingots was devised, using recycled material from a supplier and reused material from the factory itself, such as recycled sand. The processes using recycled materials resulted in lower impacts than those using new materials. Sand recycling and sand mold preparation stages have significant impact due to the presence of binders, typically used in sand molds, and transportation by vehicles powered by fossil fuels. Abiotic depletion indicates the need to transition to renewable energy sources and sustainable materials, such as developing clean energy infrastructure. Regarding global warming, there were high values for all stages of the casting process, with the highest value in the sand recycling stage. To prevent eutrophication, proper waste management should be implemented, such as cleaner technologies in the smelter implementing efficient effluent treatment systems. Concerning freshwater ecotoxicity, the effluents generated should be treated to reduce the concentration of pollutants before being discarded in the aquatic environment.