Rare Metal Extraction & Processing: PGM, Zn, V, Ti, U, Th, In, Ag, Fe
Sponsored by: TMS Extraction and Processing Division, TMS: Hydrometallurgy and Electrometallurgy Committee
Program Organizers: Gisele Azimi, University of Toronto; Takanari Ouchi, University of Tokyo; Hojong Kim, Pennsylvania State University; Shafiq Alam, University of Saskatchewan; Kerstin Forsberg, KTH Royal Institute of Technology; Alafara Baba, University of Ilorin

Tuesday 8:30 AM
February 25, 2020
Room: 13
Location: San Diego Convention Ctr

Session Chair: Hojong Kim, Pennsylvania State University; Gisele Azimi, University of Toronto


8:30 AM  Keynote
Electrodialysis in Hydrometallurgical Proceses: Odne Burheim1; Liyuan Deng1; Kerstin Forsberg2; Øivind Wilhelmsen1; Pauline Zimmermann1; 1Norwegian University of Science and Technology; 2KTH
    Albeit electrodialysis is a membrane process originally developed for sea water desalination, it is possibly even more suited for separation in various hydrometallurgical processes. Several examples of such process have been demonstrated or demonstrated in a relevant environment. Particularly this context is when it comes to separating cations with different valences or likewise for anions of different valences. This has been done successfully by using membranes that are modified on the surface as to block ions of higher valences. Moreover, when having compositions with components of large differences in molarity, it has been demonstrated that utilisation of the boundary layer transport properties can be used for cationic species separation or likewise for anionic species separation. Given these examples the possibility for electrodialysis in hydrometallurgical processes is vast. The presentation will highlight some of these possibilities.

9:00 AM  
Leaching of Eudialyte –The Silicic Acid Challenge: Dag Eriksen1; Kurt Forrester1; Mark Saxon1; 1Primus.inter.pares AS
    Heavy rare earth elements (HREE) are considered as a group of critical elements of high supply risk. The most abundant mineral containing HREE is xenotime, YPO4, but to extract Y and the substituting HREE tough handling to dissolve the phosphate is required. Eudialyte, on the other hand, is much less common, but is easy to leach. The mineral is basically an alkaline zirconium silicate and it is leachable at pH < 3. This means that even organic acids or dilute mineral acids may be used for the leaching. However, the challenge with eudialyte is that silicates are also dissolved and after a while these silicates may form gels. Usually the silicates are referred to as silicic acids. Such gels have detrimental effect on chemical processes where fluid flows are imperative. The presentation will seek to present published and unpublished efforts conducted to find ways of omitting this problem.

9:20 AM  
Co-precipitation of Impurity (Ti, Fe, Al, Zr, U, Th) Phases during the Recovery of (NH4)3ScF6 from Strip Liquors by Anti-solvent Crystallization: Edward Peters1; Carsten Dittrich2; Bengi Yagmurlu2; Kerstin Forsberg1; 1KTH Royal Institute of Technology; 2MEAB Chemie Technik GmbH
    Scandium can be extracted from waste streams of other industrial processes, particularly the bauxite residue and TiO2 acid waste, by acidic leaching and solvent extraction of the leach solutions. Stripping of the organic phase using NH4F solutions produces strip liquors containing Sc (>2000 mg/L). Scandium can be separated from these liquors by anti-solvent crystallization of (NH4)3ScF6. In this study, the extent to which impurities co-precipitate as separate crystalline phases or are incorporated into the crystal lattice of (NH4)3ScF6 was investigated. The impurity metals Fe, Zr and U co-precipitated with the Sc phase. Moderate Ti precipitation was only observed from strip liquors containing mainly Fe and Ti impurities. Detection of these phases by powder XRD was difficult due to almost similar peak positions of the ammonium metal hexafluoride salts. However, EDS confirmed that the impurity metals were present in the precipitates in relative abundances that matched non-proportionally those of the initial strip liquors, except for Ti. SEM images showed that (NH4)3ScF6 crystals obtained from strip liquors containing predominantly scandium were bigger (2–3 μm) compared to crystals of the mixed precipitate samples (< 2 μm) obtained from strip liquors containing relatively high impurity levels. This could be attributed to surface diffusion impediment of one metal ion by other metal ions at the solid-liquid interface and surface incorporation of foreign metal ions in the growth steps or kinks of one solid phase, thereby reducing the crystal growth rate of that phase. The excess supersaturation is then consumed by more crystal nucleation as observed.

9:40 AM  
Impurity Uptake during Cooling Crystallization of Nickel Sulfate: Ina Beate Jenssen1; Seniz Ucar1; Oluf Bøckman2; Ole Morten Dotterud2; Jens-Petter Andreassen1; 1Norwegian University of Science and Technology; 2Glencore Nikkelverk AS
    The ever-increasing battery production for electric vehicles leads to a need for recycling of valuable metals used in batteries, such as nickel, for a sustainable development. Nickel can be recovered from process streams or side streams in hydrometallurgical industry as nickel sulfate by crystallization, in order to obtain high purity products for applications like battery-grade nickel sulfate. In this work, NiSO4*6H2O was precipitated by cooling crystallization in a temperature-controlled batch reactor, and uptake of chloride, sodium and magnesium was investigated. Precipitates were characterized by XRD and their impurity contents were determined by ICP-MS. Increasing impurity concentrations in the reactor gave increased impurity uptake, and the highest uptake was provided by magnesium. The results indicated that sodium and chloride were adsorbed on the crystal surface, while magnesium was incorporated in the bulk of the crystals, possibly explained by the similar properties of nickel and magnesium.

10:00 AM  
Potential of a Nigerian Cassiterite Ore for Industrial Steel Coatings: Alafara Baba1; Abdulrasheed Yusuf1; Folahan Adekola1; Abdul Alabi2; Kuranga Ayinla1; Abdullah Ibrahim1; Christianah Adeyemi3; Mustapha Raji1; Sadisu Girigisu3; Rasaki Gbadamosi1; Aishat Abdulkareem4; 1University of Ilorin; 2Kwara State University, Malete; 3Federal Polytechnic Offa; 4National Mathematical Centre, Sheda-Kwali
    As the world demand for pure tin and its compounds are quite steady with an estimated projection of 5% per annum and coupled with its wide array of applications in iron and steel industries in Sub-Sahara Africa, the need for continuous ore purification has become paramount. Thus, the treatment of Nigerian cassiterite ore for industrial value addition by selective acid leaching and solvent extraction was investigated. The effects of leachant concentration, temperature and particle size on ore dissolution rates were examined. At optimal leaching conditions, 76.7 % ore reaction was achieved within 120 minutes. Tin recovery from the leach liquor by 0.5 mol/L tributyl phosphate (TBP) in kerosene at 27±2°C gave 89.31% efficiency. Stripping of tin from organic-loaded phase recorded 98.9 % purity and beneficiated to obtain high grade tin chloride (SnCl2, melting point: 239.7 °C; density: 3.89 g/cm3), suitable as steel coating indices in some defined indigenous steel industry.

10:20 AM Break

10:35 AM  
The Iron Precipitate from Primary Zinc Production – A Potential Future Source for Indium and Silver: Stefan Steinlechner1; Lukas Höber1; 1Montanuniversitaet Leoben
    Indium as a so-called hitchhiker metal is extracted almost entirely in course of the primary zinc production. Thus, a strong dependence on the output of the corresponding base metal is given. Taking the annually growth rate of approximately 3 wt-% in the case of zinc production and the one from indium, respectively around 15 wt-% into account, it is obvious that a shortage is faced. Because of the relative new application area of indium in high-tech products a great potential of dumped indium is present in the residues of the past production. Therefore, the present paper describes the characterization and the possible treatment of such a residue, including the thermodynamic background for a pyrometallurgical extraction of indium and silver.

10:55 AM  
Recovery of Platinum Group Metals from Secondary Sources by Selective Chlorination from Molten Salt Media: Ana Maria Martinez1; Karen Osen1; Anne Støre1; 1Sintef
     The use of molten salts as "solvents" offer interesting possibilities for the treatment of ores, industrial by-products as well as scrap, allowing the development of processes that are mid-way between pyro-and hydrometallurgy, with the advantage of salts offering a wide choice of chemical and electrochemical properties. The molten mixtures can be fed to industrial electrolytic cells (electrometallurgy) where the reactions can take place. One example of this type of reactions is the selective chlorination using gaseous mixtures in a molten chloride salt mixture.Within the frame of the EU-financed project PLATIRUS (GA730224), SINTEF has investigated the possibility of selective chlorination of the platinum group metals (PGM) contained in secondary sources (e.g. spent car catalyst), using molten salts as reaction media. In this way, the extraction of valuable PGM from the waste matrix can be carried out selectively in a single and simple step, without prior up-concentration of the waste material.

11:15 AM  
Reclamation of Precious Metals from Small Electronic Components of Computer Hard Disks: Rekha Panda1; Manis Kumar Jha1; Om Shankar Dinkar1; Devendra Deo Pathak2; 1CSIR-National Metallurgical Laboratory; 2Indian Institute of Technology (ISM)
    Present research work focus on the recovery of precious metals (Ag, Au, Pd and Pt) from the leach liquor of small populated chips present in the hard disks of computers. Initially, the hard disks were dismantled to separate the printed circuit boards (PCBs) followed by its depopulation to liberate the mounted small electronic parts. The liberated black chips were pulverized and physically beneficiated by wet scrubbing technique to separate the metallic and non-metallic fractions. The metallic concentrate (containing ~0.6% Ag, ~0.3% Au, ~0.01% Pd, ~0.0003% Pt, 20% Cu, etc.) was first leached in nitrate medium for maximum dissolution of non-ferrous metals along with Ag leaving Au, Pd and Pt in the residue. About 99.99% precious metals were leached out from the residue using suitable lixiviant. The obtained leach liquor was purified using advance separation techniques (solvent extraction/ ion-exchange/ precipitation) from which marketable products (metals/ salts) could be produced.