Purification of post-consumer steel scrap

Abstract

Post-consumer steel scrap is often handpicked for contaminants, such as copper, to meet the specifications of steelmakers. If the hand sorting capacity exceeds 20 t scrap/h, the efficiency generally becomes problematic, leaving 50% of the copper contaminants in the steel product. In response, new technologies are emerging that facilitate hand sorting of these types of scrap. The advantages are increased revenues, expanded plant capacity and higher and more consistent steel product quality. A shape sensitive magnetic separator is proposed that presorts scrap into two products. One is a bulky, thin walled steel fraction of high purity, and the other is a volumetrically small flow of relatively heavy parts, including the contaminants. The concentrated contaminant product is amenable for effective sorting by hand pickers or for sensor sorting but could also be sold directly to specialised sorters that extract the copper. Detailed results for the magnetic sorter are reported for midsized incineration bottom ash scrap.