Pretreatment of automobile shredder residue (ASR) for fuel utilization

Abstract

Automobile shredder residue (ASR) was pretreated to improve its quality for fuel utilization. Composition analysis revealed that ASR components could be classified into four groups: (1) urethane and textile—light fraction and combustibles containing low levels of ash and Cl; (2) plastics and rubber—light or heavy fraction and combustibles containing high levels of Cl; (3) metals and electrical wire—heavy fraction and incombustibles, and (4) particles smaller than 5.6 mm with high ash contents. Based on these results, we successively performed sieving to remove particles smaller than 5.6 mm, float and sink separations to reject the heavy fraction and plastics and rubber containing Cl, thermal treatment under an inert atmosphere to remove Cl derived from PVC, and char washing to remove soluble chlorides. This series of pretreatments enabled the removal of 78% of the ash and 91% of the Cl from ASR. Sieving using a 5.6-mm mesh removed a considerable amount of ash. Product quality was markedly improved after the float and sink method. Specifically, the sink process using a 1.1 g cm −3 medium fluid rejected almost all rubber containing Cl and a large amount of PVC. The remaining Cl in char, after heating at 300 °C under an inert atmosphere and washing, was considered to be present as insoluble chlorides that volatilized at temperatures above 300 °C. Based on a tradeoff relationship between product quality and treatment cost, ASR may be utilized as a form of refuse plastic fuel or char.