Material and Energy Beneficiation of the Automobile Shredder Residues

Abstract

Although vehicles represent a main key of our modern society, they affect our environment via the energy and resource consumption, waste generation during their manufacturing as well as greenhouse gas emissions all along their use. Further, hazardous residues are produced at the end-of-life vehicles “ELV”. After collection and dismantling, the remainders of the ELV are directed to shredding operator followed by a series of mechanical and physical separations in order to recover the ferrous and non-ferrous metals. The residue of the shredding process, called automobile shredder residue “ASR” represents about 20–25% of the ELV. The ASR, while toxic enough to be classified as hazardous waste, could be considered as material and energy sources.

The present study deals with the possibility of material and energy beneficiation of the ASR by its use in the metallurgical units. ASR samples from an European automobile shredder company were collected and subjected to the physical separation process followed by a thermodynamic approach and isothermal batch tests to assess the reducing performance and energy capacity of the ASR hydrocarbon matter. Particular attention was devoted to the behavior of several residual and tramp elements (Cl, Pb, Cu, Zn) affecting the metallurgical process and the product quality. Results showed that physical operations (screening, attrition, dry low intensity magnetic separation) lead to a selective extraction of the mineral part of the ASR which can be directed to the blast furnace unit. Direct reduction of hematite by the plastics contained in the ASR was obtained at 1000–1050 °C resulting into multistage steps of Fe₂O₃ converting into metallic iron. Multi-parametric analysis of the results suggests that the purified ASR can partially substitute raw materials used in pig iron and steel production.