Recycling and Sustainability for Emerging Technologies and Strategic Materials: Recycling and Process Optimization I
Sponsored by: TMS Extraction and Processing Division, TMS Light Metals Division, TMS: Recycling and Environmental Technologies Committee
Program Organizers: John Howarter, Purdue University; Mingming Zhang, Baowu Ouyeel Co. Ltd; Elsa Olivetti, Massachusetts Institute of Technology; Hong (Marco) Peng, University of Queensland
Wednesday 8:30 AM
March 17, 2021
Room: RM 24
Location: TMS2021 Virtual
Session Chair: Hong Peng, University of Queensland
8:30 AM
Copper Separation from Steel Scrap: Hyunsoo Jin1; Brajendra Mishra1; 1Worcester Polytechnic Institute
Copper impurities in scrap restrict the recycling of steels due to surface defects and loss of ductility in products. At present, the dilution method is the best and efficient way and is widely used where low impurity iron-bearing products, relatively pure iron are mixed with high copper post-consumer scrap to lower its negative impacts. However, the composition of steel scrap will show more copper and tin because of more electric appliances, electric vehicles and other WEEE needed to be reprocessed. Therefore, the dilution method will face some processing as well as cost limitations, since low impurity iron sources are expensive and scrap will need to be reused. Roughly, there are two strategies for refining one is based on hydrometallurgy for surface copper contamination whereas, pyrometallurgical techniques are suitable for bulk copper and tin contamination. Specifically, the aluminum bath extraction method, has been conducted for different heat treating temperature and time.
8:50 AM
Improvement of Steel Scrap Recycling: Optical Recognition of Cu Impurities Using Machine Learning: Zhijiang Gao1; 1Colorado School of Mines
Cu impurities in steel scrap, mainly presented as motors and wires, could induce surface hot shortness during hot working recycled steel with high Cu content, limiting the efficiency of recycling. Impurity removal methods have been developed, including physical separation and chemical treatment, to overcome such detrimental effects. For physical separation, optical recognition was explored as a type of sensor-based sorting method, apart from regular shredding and magnetic separating, considering either the Cu metal in the motor rotors with reddish-brown color and the Cu wire with colorful insulation, or the potential difference of shape geometry between Cu impurities and Fe shreds. To further improve the optical detection, image classification through machine learning was adopted to optimize the recognizing process of shredded scrap collected from auto shredders. The results show that better recognition of Cu impurities could be achieved, resulting in a reduction of Cu content.
9:10 AM
Copper Supply for Electric Vehicles and Impacts on the Recycling Sector: Ayomipo Arowosola1; Gabrielle Gaustad2; 1Rochester Institute of Technology; 2Alfred University
The transition from internal combustion engine (ICE) vehicles to electric vehicles (EV) is currently accelerating. The market for EVs is uncertain due to inter-related environmental, social, and economic parameters that drive adoption and market demand. EVs and ICEs differ greatly in the materials that are required to manufacture them. Here, we have focused on the increasing demand for copper, a strategic material for EVs. Data mining and material characterization were performed in order to develop a forecasting model. Our results show that in the short term (to 2030), available primary and secondary supply should keep pace with increasing copper demand due to EV adoption. However, in the long-term, an increase in supply will be required, likely from secondary materials. The high diversity of metal alloys introduced by increased EV adoption creates unique challenges for the recycling sector, however. Technology (e.g. sorting, smelting) or policy interventions (e.g. mandates) are likely required.
9:30 AM
Development and Impact of High-performance Al Alloys Alloyed with Rare Earth Co-products: Hunter Henderson1; Zachary Sims2; David Weiss3; Tomer Fishman4; Ryan Ott5; Orlando Rios2; Scott McCall1; 1Lawrence Livermore National Laboratory; 2University of Tennessee-Knoxville; 3Eck Industries, Inc.; 4IDC Herzliya; 5Ames Laboratory
The production of industrial by-products is a persistent issue that has plagued the economics and sustainability of manufacturing throughout history. We propose a methodology wherein low value rare earth element (REE) waste products may be repurposed to develop high performance products with exceptional value, thereby increasing REE production and decreasing the criticality of other REE. Al-REE alloys are an emergent material with the capability to push boundaries of performance, especially in weight critical applications like transportation. The exceptional castability and thermal stability of Al-REE alloys enable performance outside of normal limits of Al alloys. Here, we discuss how this alloy can address REE supply imbalances and the potential impacts of deployment of Al-REE deployment on the diversity of REE production. Associated opportunities for improvements to existing Al recycling streams by the introduction of this material will also be discussed.
9:50 AM
Electrochemical Separation of Aluminum from Mixed Scrap Using Ionic Liquids: Aninda Nafis Ahmed1; Ramana Reddy1; 1The University of Alabama
Electrodeposition of aluminum experiments were conducted in three types of ionic liquids (IL); EMIC, BMIC and HMIC with AlCl3. The molar ratio of IL:AlCl3=1:2 was determined to be optimum molar ratio for all three ILs. Over 170 A/m2 current density with more than 85% current efficiency was obtained for EMIC. Similarly, for BMIC, over 300 A/m2 current density was found with more than 85% current efficiency and for HMIC, more than 250 A/m2 of current density with over 85% current efficiency was obtained. Based on the lab-scale experimental findings, scale up experiments were carried out for BMIC:AlCl3=1:2 molar ratio. Significant increase in current density was observed when higher potentials were applied. More than 220 A/m2 of current density was found in a scale up system. Additionally, lower distance between anode and cathode (~1cm) and higher stirring rate (120 rpm) produced higher current densities. Outcome of this work would facilitate the scale up studies for the electrochemical separation of aluminum from mixed scrap.
10:10 AM
High-temperature Oxidation of Explosion Welded Tantalum-tungsten Alloy on Steel Substrate as a Potential Technique for Recycling: Akanksha Gupta1; Brajendra Mishra1; 1Worcester Polytechnic Institute
In recent years, tantalum is being increasingly researched as a potential coating material on steel substrate for application in gun barrels. This study is focused on a potential recycling route of such composite material at its end of life. High-temperature oxidation is studied as a potential route for recycling of tantalum alloy explosion-welded on steel. The oxidation tests are carried out in box furnace between 500-1000C. Oxidation kinetics was studied by measuring weight gain per unit area with change in temperature and time. The microstructural change is analysed using scanning electron microscopy, and structural change is analysed using X-ray diffractometer. Moreover, a comparative oxidation study is carried out on samples- Tantalum cold-sprayed on 4130 steel and Tantalum cold-sprayed on A36 steel. This is used to analyse the effect of coating, substrate and deposition technique on oxidation of tantalum coated steel. Some reuse opportunities of recovered tantalum oxide will be presented.