Scandium Extraction and Use in Aluminum Alloys: Scandium - Extraction/Mining and Master Alloy Production
Sponsored by: TMS Light Metals Division, TMS: Aluminum Committee
Program Organizers: Timothy Langan, Sunrise Energy Metals; Samuel Wagstaff, Oculatus Consulting; Phil Chataigneau, Ppk Group Australia / Pdu Inc. ; Efthymios Balomenos, Mytilineos S.A., Metallurgy Bu; Thomas Dorin, Deakin University; M. Akbar Rhamdhani, Swinburne University of Technology; Dimitrios Filippou, Rio Tinto Iron & Titanium; Henk van der Laan, V.I.C. Van der Laan International Consultancy BV; Frank Palm, Airbus Defence and Space GmbH

Monday 2:00 PM
March 20, 2023
Room: 30D
Location: SDCC

Session Chair: Henk van der Laan, V.I.C. Van der Laan International Consultancy BV


2:00 PM Introductory Comments

2:05 PM  
Investigations into Optimized Industrial Pilot Scale BR Leaching for Sc Extraction: Efthymios Balomenos1; Panagiotis Davris1; Alexandra Apostolopoulou1; Danai Marinos2; Elena Mikeli2; Aikaterini Toli2; Dimitris Kotsanis2; Grigoris Paschalis1; Dimitrios Panias2; 1Mytilineos S.A., Metallurgy Bu; 2NTUA
    Scandium is a critical metal with increasing demand in modern technologies, like oxide fuel cells, light-weight Al-Sc alloys and it is present at considerably high concentrations in various metallurgical by-products, including the bauxite residue (BR). Scandium extraction from the Greek bauxite residue (BR) that contains 70–100 mg/kg Sc has been demonstrated at an industrial pilot plant at MYTILINEOS. BR has been treated with sulfuric acid at conditions that allow for low acid consumption. In such conditions, high Sc leaching selectivity is achieved over Fe and Ti, which are the main impurities for the further purification of the leachate through the ion-exchange technique. This paper reports on the recent investigations on the effect of pH control during the leaching process, which can lead to optimized Sc leaching yields. Moreover, the treatment of the produced leachate solution is also studied, in order to further refine it, prior to the ion-exchange.

2:30 PM  
Solvent Extraction of Scandium from Titanium Process Solutions: Dimitrios Filippou1; Michel Paquin1; Yves Pépin1; Mike Johnson2; Niels Verbaan2; 1Rio Tinto Iron & Titanium; 2SGS Canada Inc.
    Scandium is present in titanium dioxide feedstock (ilmenite, titania slags, etc.) and usually reports to process solutions and effluents either at the feedstock producer site or at the end user site (TiO2 pigment or Ti metal plant). In this paper, we report on the refining of scandium from such solutions by solvent extraction. A mixture of D2EHPA and TBP was used to extract scandium from a scandium-rich intermediate aqueous solution, which had been previously recovered from a titania slag upgrading process. Scandium loaded organic was scrubbed with H2SO4 to remove titanium and thorium, and the scrubbed organic was stripped with NaOH to produce an impure scandium hydroxide precipitate. The precipitate was dissolved in H2SO4, and the resulting solution was treated further with Alamine® 336 and Aliquat® 336 to remove persistent impurities. The formation of solids in the D2EHPA stripping step was a significant process issue, but ultimately high purity scandium oxide was produced. For reasons not related to the work reported here, Rio Tinto eventually selected other processing methods for its scandium extraction plant in Sorel-Tracy, QC, Canada.

2:55 PM  
State of the Art Technologies for Scandium Recovery, Purification, and Aluminum-Scandium Alloy Production: Anne Marie Reyes1; Gomer Abrenica1; Ghazaleh Nazari1; 1Coherent
     Aluminum-based alloys containing minimal amount of scandium have been extensively investigated for their exceptional mechanical properties which make them particularly suitable for advanced engineering applications such as aerospace and defense by allowing design and construction of high-strength, lightweight structural parts.Understanding the challenges in scandium sourcing, recovery and purification processes, and alloying methods, a vertically integrated solution has been developed which includes a portfolio of technologies: (i) patented recovery of Sc from Sc-containing ores and industrial waste streams from ppm levels to 20-25 % in the concentrate – validated in the pilot scale; (ii) purification of Sc from concentrates containing impurities such as titanium, iron and other rare earths to produce >99.5 % pure scandium oxide – validated in the commercial scale; and (iii) patent-pending technology for production of the final alloy through a one-step alloying process using a vacuum induction furnace, refined casting technique, and suitable heat treatment processes – validated at demonstration scale.

3:20 PM  
FEA Materials - AlSc Master Alloy Production Technology: Eugene Prahin1; Rick Salvucci1; Brian Hunt1; 1FEA Materials LLC
    There are three common production techniques for AlSc: Sc dissolution, aluminothermic reduction and electrolysis. These techniques have well known shortfalls, including time intensive, costly, composition, impurities, etc. FEA Materials has developed a process that overcomes some of these shortfalls. FEAM Process is a hybrid metallothermic/electrolysis process that enables low-cost production of AlSc. It can achieve Sc concentrations up to 8wt% in the alloy, runs continuously and maintains a material yield above 90%. A proprietary molten salt composition is used that is robust and self-correcting, overcoming the challenges with traditional electrolysis processes. The technology platform is modular, allowing for tuned production rates and flexible infrastructure requirements. It runs semi-continuously and sealed under inert atmosphere to keep tight control of the output streams and ensure a safe work environment. FEAM is currently producing 4kg of material per shift with the capability to expand to 50kg/shift within its existing facility.

3:45 PM Break

4:00 PM  Invited
Scandium Master Alloy Production via Sulfidation and Vacuum Aluminothermic Reduction: Caspar Stinn1; Ethan Benderly-Kremen1; Antoine Allanore1; 1Massachusetts Institute of Technology
    Scandium is a critical component for high strength aluminum products, yet manufacture is burdened by challenges in metal reduction and alloying. Current best practice begins with generation of a scandium-aluminum master alloy from oxide or halide precursors. However, this approach is characterized by high costs and large environmental impacts. Recent results have shown that employing a metal sulfide feedstock for aluminum master alloy production increases metal yield and improves process economics. Herein, we conduct the sulfidation of scandium oxide using elemental sulfur to generate a scandium sulfide intermediate, which we experimentally confirm to be amenable for reduction to metal. We demonstrate production of aluminum-scandium master alloy at the hundred-gram scale from scandium sulfide using aluminothermic reduction via reactive vacuum distillation. Chemical analysis is conducted to determine product purity and yield. Operating conditions to manufacture master alloys with scandium contents of 2 wt% and higher are identified.

4:25 PM  Invited
European Scandium for a Lighter and Greener Future: Henk van der Laan1; Beate Orberger2; 1V.I.C. Van der Laan International Consultancy BV; 2CATURA Geoprojects
    Scandium is a soft silvery metal, with an atomic number of 21 it is the lightest of the transition metals. The melting point is 1.541 °C, the boiling point is 2.836 ° C and with a density of 2,985 g/cm³ is slightly heavier than Aluminium. Scandium is actual not rare – it is more abundant than precious metals and commercial metals like cobalt, lead and mercury. Scandium is primarily produced as a byproduct from the mining of other metals or minerals like Bauxite, Coal, Rare Earth Elements (REE), Iron, Tungsten, Uranium, Zirconia or Titaniumdioxide. Scandium and scandium compounds have unique properties for many advanced technological applications. Scandium is considered as a Strategic metal by the EU and by the US government due to the current limited Western supply situation. Scandium is increasingly used in energy storage systems such as solid oxygen fuel cells (SOFC) and for green hydrogen production in solid oxide electrolyser cells (SOEC). AlScN piezoelectric films for energy generation are important compounds for 5G applications. Today, the EU imports 100 %, mainly from China. Therefore, a continuous supply of scandium at reasonable prices must be ensured in and for Europe, and the dependency from China must be reduced. Europe is leading in the development of green technologies and has sufficient scandium resources.

4:35 PM Panel Discussion Scandium Supply