How Will Copper Contamination Constrain Future Global Steel Recycling?

Abstract

Copper in steel causes metallurgical problems, but is pervasive in end-of-life scrap and cannot currently be removed commercially once in the melt. Contamination can be managed to an extent by globally trading scrap for use in tolerant applications and dilution with primary iron sources. However, the viability of long-term strategies can only be evaluated with a complete characterization of copper in the global steel system and this is presented in this paper. The copper concentration of flows along the 2008 steel supply chain is estimated from a survey of literature data and compared with estimates of the maximum concentration that can be tolerated in steel products. Estimates of final steel demand and scrap supply by sector are taken from a global stock-saturation model to determine when the amount of copper in the steel cycle will exceed that which can be tolerated. Best estimates show that quantities of copper arising from conventional scrap preparation can be managed in the global steel system until 2050 assuming perfectly coordinated trade and extensive dilution, but this strategy will become increasingly impractical. Technical and policy interventions along the supply chain are presented to close product loops before this global constraint.

Weighing regional scrap availability in global pathways for steel production processes

“…The end-of-life recovery rate for iron and steel products has been estimated to be in a range between 70 and 90% (Graedel et al 2011a, b). Previous studies indicate that there is a need for a coordinated, global effort for avoiding copper contamination of scrap resources by 2030 (Daehn et al 2017).…”

Material efficiency strategies to reducing greenhouse gas emissions associated with buildings, vehicles, and electronics—a review

“…Such downcycling constitutes itself an energy loss: pig iron production causes emissions of 1.5 kg CO 2 equivalent per kg iron, while alloying elements range from similar (1.9 kg CO 2 /kg metal for ferrochromium) to much higher (11 kg CO 2 /kg nickel from sulfide ores) [170], so that the emissions associated with highly alloyed steel can be significantly higher than those of construction steel. Further, alloying elements and other metals mixed in as part of the shredding process become contaminants that compromise the quality of the material in question even for bottom applications, potentially leading to a future where secondary material needs to be discarded [154,171]. Copper and tin contamination limits the usefulness of secondary steel and scenarios foresee a possible saturation of the steel stock with copper within material tolerances, impeding further recycling [171].…”

“…Further, alloying elements and other metals mixed in as part of the shredding process become contaminants that compromise the quality of the material in question even for bottom applications, potentially leading to a future where secondary material needs to be discarded [154,171]. Copper and tin contamination limits the usefulness of secondary steel and scenarios foresee a possible saturation of the steel stock with copper within material tolerances, impeding further recycling [171]. Similarly, secondary aluminum will need to be discarded unless alloy-specific recycling is introduced, in particular when internal combustion engine blocks, which currently absorb much of the low-quality supply, are no longer needed [154].…”

Potentiale der Kreislaufwirtschaft zur Reduktion des Ausstoßes von Treibhausgasen

“…in geringerem Maß auch mit anderen Elementen wie etwa Nickel, dar [16]. Bereits geringe Anteile von Kupfer im Stahl können die Qualität drastisch verringern, so wird Stahl bereits ab einem Kupfergehalt von lediglich 0,1 % für zahlreiche Anwendungen unbrauchbar [17]. Da Kupfer aus dem Stahl praktisch nicht mehr zu gewinnen ist, führt die Verunreinigung zu einer dauerhaften Abwertung des Materials.…”