Rare Metal Extraction & Processing: Li, Co, Au, Ag, PGMs, Te, Na, W, In
Sponsored by: TMS Extraction and Processing Division, TMS: Hydrometallurgy and Electrometallurgy Committee
Program Organizers: Gisele Azimi, University of Toronto; Takanari Ouchi, University of Tokyo; Kerstin Forsberg, KTH Royal Institute of Technology; Hojong Kim, Pennsylvania State University; Shafiq Alam, University of Saskatchewan; Alafara Baba, University of Ilorin; Neale Neelameggham, IND LLC

Monday 2:00 PM
March 15, 2021
Room: RM 44
Location: TMS2021 Virtual


2:00 PM  Invited
Environmental Aspects of the Electrochemical Recovery of Tellurium by Electrochemical Deposition-redox Replacement (EDRR): Petteri Halli1; Marja Rinne1; Benjamin Wilson1; Kirsi Yliniemi1; Mari Lundstrom1; 1Aalto University
    The current study investigates the energy consumption and the corresponding global warming potential (GWP) of tellurium recovery from multimetal solution by the use of a tailored electrochemical recovery approach based on electrodeposition-redox replacement (EDRR). A three electrode cell was used to recover Te from synthetically prepared pregnant leach solution similar to the PLS of leached Doré slag (30% aqua regia, [Cu] = 3.9 g/L, [Bi] = 4.6 g/L, [Fe] = 1.4 g/L, and [Te] = 100-500 ppm). Enrichment of Te on the electrode (with 100 EDRR cycles) had a calculated global warming potential of 3.7 CO2 -eqv from a solution with 500 ppm Te based on a Finnish energy mix. In comparison, a decrease of Te concentration to 100 ppm increased the corresponding environmental impact to 16.9 CO2 -eqv. Overall, GWP was shown to be highly dependent on the geographical area i.e. the dominating energy production methods.

2:20 PM  
Sodium Metal from Sulfate: Jed Checketts1; Neale Neelameggham2; 1Powerball Industries; 2IND LLC
    A new method of making sodium metal from sodium sulfate is discussed. Anhydrous sodium sulfate as may be made from sodium sulfate waste solutions is reduced with aluminum metal. The reactor design to make sodium metal along with aluminum and sulfur oxides minimizing wastes is explored. Thermochemical tools are used in this development. Experiments carried out in this regard and how they fit the thermochemistry is evaluated in this paper.

2:40 PM  
Preparation of High-grade Ammonium Metatungstate (AMT) as Precursor for Industrial Tungsten Catalyst: Alafara Baba1; Sadisu Girigisu1; Mustapha Raji1; Abdullah Ibrahim1; Daud Olaoluwa1; Kuranga Ayinla1; Christianah Adeyemi1; Aishat Abdulkareem1; Abdul Alabi2; Mohammed Abdul3; 1University of Ilorin; 2Kwara State University, Malete; 3Federal Polytechnic, Offa
    The increasing demand for pure tungsten and its compounds considering their high tensile strength warrants their usefulness in catalyst, heavy alloy, cemented carbide, among others. This exceptional property also signals its interest by industrialists for use in the engineering and manufacturing sectors. Thus, preparation of AMT from a Nigerian wolframite ore by hydrometallurgical process was examined in sulphuric-cum-phosphoric acid solutions. During leaching, parameters such as leachant concentration, reaction temperature and particle size on ore dissolution were examined. At optimal conditions (2.0M H2SO4 + 0.15M H3PO4, 75°C, -63µm), 93.7% of the ore reacted within 120 minutes. The calculated activation energy of 6.93kJ/mol supported the proposed mechanism. The leachate at optimal conditions was analytically treated to obtain a pure tungstate solution. The purified solution was further beneficiated to produce a high grade AMT ((NH4)6[H2W12O40].4H2O : 96-901-3322, melting point: 98.7°C, density: 2.16g/cm3), which could serves as an intermediate material for some defined industries.

3:00 PM  Invited
Extraction of Platinum Group Metals from Spent Catalyst Material by a Novel Pyro-metallurgical Process: Ana Maria Martinez1; Kai Tang1; Camilla Sommerseth1; Karen Osen1; 1SINTEF
    The extraction of platinum group metals (PGM) contained in waste automobile catalyst monolithic honeycomb was investigated by a novel approach that combines a pyro-metallurgical and electrolysis step. The first step aims to both up-concentrate the amount of PGMs by using a metal collector, as well as to prepare the conductive material to be used as anode in the electrolysis step. The electrolysis step is carried out in a molten chloride electrolyte, where the PGMs remains as metallic residue, and the refined metal is further reused in the pyro-metallurgical step. Optimisation of the pyro-metallurgical process led to 82-106% metal recovery rates, while the PGM recovery rates were close to 100%. Furthermore, the electrolyte composition and working temperature, as well as cell design of the subsequent electrolytic method were adjusted. The process was assessed in a lab-scale electrolysis reactor, where PGMs could be extracted selectively with a current efficiency of ca. 70%.

3:20 PM  
Developed Commercial Processes to Recover Au, Ag, Pt and Pd from E-waste.: Rekha Panda1; Manis Kumar Jha1; Jae-chun Lee2; Devendra Deo Pathak3; 1CSIR-National Metallurgical Laboratory; 2Korea Institute of Geosciences and Mineral Resources (KIGAM); 3Indian Institute of Technology (ISM) Dhanbad
    Due to the supply gap towards increasing demand as well as loss of precious metals by illegal recycling, present research reports application oriented processes developed at CSIR-NML, India to recover precious metals from small components of e-waste containing ~0.1-0.8% Ag, ~0.03-0.9% Au, ~0.01-0.02% Pd, ~0.0003-0.0005% Pt and related effluent. Firstly, ~99.99% Au was recovered from plated e-waste using the process of selective leaching followed by charcoal adsorption and heat treatment whereas the second process consists of dismantling, physical/ chemical pre-treatment of e-waste followed by hydrometallurgical processing to recover 99% Ag, 99.9% Au, 95% Pd and 90% Pt. Apart from the above, leaching and selective precipitation were used to recover ~95% Ag from waste computer keyboards. The effluent generated during the e-waste processing was found to contain ~8-10 mg/L Au, which was also recovered using ion-exchange technique. All processes presented are scientifically validated and after scale-up studies commercially viable.