Distribution characteristics of PCDDs/PCDFs in products generated from Pyrolysis/ gasification/ melting process of automobile shredder residues

In Korea, the number of automobiles in use is around 15,400,000 and 500,000 End-of-Life Vehicles (ELVs) are generated annually. About 80,000 of ELVs are exported and rest of them are dismantled and shredded to recover valuable parts. After recovering steel at a shredding factory, the residue (automobile shredder residue; ASR) is left and this can be converted into any fuel forms such as gas, oil, or char using pyrolysis or gasification technology. In this study, dioxin concentrations and distributions of congeners in products (i. e. the yields of gas, oil, char and melting slag) from ASR pyrolysis, and dioxin concentrations in ASR are analyzed to compare the products of pyrolysis. In addition, the emission characteristics of dioxin at different air/fuel ratios and the distribution of dioxin concentrations in melting slag are investigated. ASR was found containing about 6 pg-TEQ/g of dioxins with more chlorinated congeners. Product gas in the presence of oxygen (gasification) shows 75 times higher concentration of dioxins than that with no oxygen present (pyrolysis). Oil produced by pyrolysis contained more chlorinated dioxins and char product showed higher dioxin concentration at air existence. All products, gas, oil, and char, tend to include more PCDFs than PCDDs because of lack of oxygen during pyrolysis. The obtained results will be used as basic data for developing pyrolysis, gasification and melting technologies of ASR in future.