Recycling without Melting: An Alternative Approach to Aluminum Scrap Recovery

Abstract

Method of scrap recovery by hot extrusion in a contrast to traditional aluminum recycling process distinguishes itself with a low energy consumption and high recovery efficiency. Additionally, this type of recycling allows to recover materials even from highly fragmented forms of metal like chips, foils or filings by omitting melting procedure. In the present study results of 413.0 aluminum chips plastic consolidation will be presented. Chips after machining process were used as a charge material for the entire recycling process. In order to determined the best emulsion elimination method, three separate processes such as centrifugation, annealing and pressing were carried out. In result dry, wet and cleaned chips in a form of cylindrical billets were hot extruded into longitudinal square cross-section profiles. Mechanical properties were examined by uniaxial tensile tests while microstructure observations were performed by means of scanning electron microscopy. It has been showed that emulsion elimination by annealing gives the best results while at the same time all extruded materials revealed no significant differences in mechanical properties.

Review of measures for improved energy efficiency in production-related processes in the aluminium industry – From electrolysis to recycling

“…This means that both the production costs and solid waste generation are reduced [70]. Good material properties are also achieved [69,70]. A nearly 90% energy saving compared to conventional recycling has been reported [74].…”

“…Recycling through hot extrusion is based on the compaction of (small) aluminium scrap into billets followed by conventional hot extrusion [69][70][71][72]. To ensure proper bonding between the scrap pieces, contact between pure aluminium surfaces must be achieved through the breaking of the oxide layers covering the scrap pieces [69,71].…”

“…This process has been shown to provide enough plastic deformation to consolidate the scrap particles [71]. Another issue which must be dealt with is contaminants, which require additional processes [70][71][72].…”

“…Compared to traditional remelting of scrap, recovery through hot extrusion has a lower energy usage as well as a higher recovery efficiency [70][71][72]. This means that both the production costs and solid waste generation are reduced [70]. Good material properties are also achieved [69,70].…”

Effect of Various Forms of Aluminum 6082 on the Mechanical Properties, Microstructure and Surface Modification of the Profile after Extrusion Process

“…350-450 • C, shortening the operation time to a few minutes and reducing energy consumption for reheating of the charge material several times. It also eliminates the risk of material losses as a result of oxidation, as surface oxidation is limited in this temperature range by a tight passivation layer [7,8].…”