Rare Metal Extraction and Processing: On-Demand Oral Presentations
Sponsored by: TMS Extraction and Processing Division, TMS: Hydrometallurgy and Electrometallurgy Committee
Program Organizers: Takanari Ouchi, University of Tokyo; Gisele Azimi, University of Toronto; Kerstin Forsberg, KTH Royal Institute of Technology; Hojong Kim, Pennsylvania State University; Shafiq Alam, University of Saskatchewan; Neale Neelameggham, IND LLC; Alafara Baba, University of Ilorin; Hong (Marco) Peng, University of Queensland
Monday 8:00 AM
March 14, 2022
Room: Materials Processing
Location: On-Demand Room
Development of New Extractants for Platinum Group Metal Ions in Hydrochloric Acid Solutions: Hirokazu Narita1; 1National Institute of Advanced Industrial Science & Technology
Solvent extraction is widely used for the separation and purification of platinum group metals (PGMs). We have studied the extraction of PGM ions from HCl solutions and found promising extractants for Pd(II) and Rh(III), respectively. Sulfide-diamide-type thiodiglycolamides (TDGAs) extract Pd(II) chloridometalates much faster than the conventionally used di-n-hexyl-sulfide (DHS). In addition, TDGAs show high stability against strongly acidic solutions, unlike DHS. The Pd(II) extracted with TDGAs can be stripped with aqueous ammonia. As for Rh(III), amide-containing tertiary amines (ACTAs), especially diamide-type and triamide-type ACTAs, efficiently extract Rh(III) in 1-5 mol/L HCl solutions, although a pentachlororhodate, [RhCl5(H2O)]2-, which is a typical unextractable complex, is dominantly present in these solutions. The high extraction efficiency would stem from the outer-sphere coordination assemblies that comprised the [RhCl5(H2O)]2- and protonated ACTAs. The loaded Rh(III) in the ACTAs can be stripped with a highly-concentrated HCl solution or NaOH aqueous solution.
Direct Synthesis of Intermetallic Compounds through Thermo-reduction and Electrochemical Deposition: Shuhan Wang1; Chao Du2; Xin Lu1; Osamu Takeda1; Hongmin Zhu1; 1Tohoku University; 2Anhui University of Science and Technology
Intermetallic compounds such as titanium aluminides, are currently produced by arc-melting of pure metals. The large difference in the melting point of the elements and the compounds, causes the difficulty to make uniform accurate stoichiometric compounds. This paper presents the possibility of direct synthesis of intermetallic compounds with precise component through thermo-reduction from the mixtures of oxide. The possibility of electrochemical deposition uniform intermetallic compounds will also be discussed.
Research Progress in Biohydrometallurgy of Rare Metals and Heavy Nonferrous Metals with an Emphasis on China: Jianzhi Sun1; Bowei Chen2; He Shang2; Xiaolan Mo2; Jiankang Wen2; 1GRINM Resources and Environment Tech. Co., Ltd.; 2GRINM Resources and Environment Tech. Co., Ltd
In the 21st century, progress in the field of biohydrometallurgy had been significant. A total of 17 novel biomining microorganisms were discovered, and 10 copper heap bioleaching plants and 12 gold biooxidation plants were established or expanded. In this review, it was summarized the physiological properties of the newly isolated biomining microorganisms and three novel microbial ecological methods for studying microbial community dynamics and structure. In addition, biohydrometallurgy research on rare metals such as uranium, molybdenum, tellurium, germanium, indium, and secondary rare metal resources, as well as heavy nonferrous metals such as copper, nickel, cobalt, and gold has been reviewed, with an emphasis on China. In future, further studies on bioleaching of low grade chalcopyrite ore, rare metals, secondary resources from waste, and environmental pollution caused by resource utilization are necessary.
Development of Molten Salt Electrolysis of MgO Using a Metal Cathode and Vacuum Distillation to Produce Ultra-high Purity Mg Metal: Jungshin Kang1; Tae-Hyuk Lee1; Hyeong-Jun Jeoung1; Dong-Hee Lee1; Young Min Kim2; Kyung-Woo Yi3; Toru H. Okabe4; Jin-Young Lee1; 1Korea Institute of Geoscience and Mineral Resources; 2Korea Institute of Materials Science; 3Seoul National University; 4The University of Tokyo
To resolve the drawbacks of the current Mg production process, the direct use of MgO as a feedstock via an electrolytic method has been attempted. In this study, molten salt electrolysis of MgO using a metal cathode such as Sn, Cu, or Ag and a graphite anode followed by vacuum distillation was developed to produce ultra-high purity Mg metal. During the electrolysis of MgO in MgF2–LiF molten salt at 1053 K, Mg alloy is produced at the bottom of the electrolysis cell owing to the high density of the cathode. Afterwards, 99.999% Mg metal is produced through vacuum distillation of the Mg alloy at 1200–1300 K. In addition, the use of secondary resources containing MgO as a feedstock, the stability of structural materials used, scale-up of the process, and the use of an inert electrode were also investigated in order to establish a cost-effective and environmentally-friendly Mg production process.
A Highly Selective Metal–organic Complex Collector for Efficient Mineral Flotation: Wei Sun1; Zhao Wei1; Haisheng Han1; 1Central South University
The increasingly low-grade, fine particle size and complex composition of mineral resources require higher efficiency and precision of flotation process. Flotation is one of the core technologies for the efficient utilization of complex low-grade resources, and the flotation reagents (especially collectors) are the scientific basis and the key of flotation technology. Metal ions have a good template effect and can regulate the structure of metal-organic complex to realize directional functional assembly. The metal-organic complex collector with metal ions as functional groups and organic ligands as hydrophobic groups has displayed excellent performance in collecting ability and selectivity, showing a new direction for the development of new flotation reagents. Metal ion-fatty acid and metal ion-hydroxamic acid complexes have made important progress in the flotation process of cassiterite, rutile, ilmenite, and rare earth ore, providing a new approach for the efficient utilization of complex low-grade mineral resources.
Method for Producing High Purity LiOH.H2O Using Ba(OH)2: Hongting Liu1; Gisele Azimi1; 1University of Toronto
In this study, a process for producing high purity lithium hydroxide monohydrate (LiOH.H2O) from synthetic lithium sulfate (Li2SO4) solution by using barium hydroxide (Ba(OH)2) is proposed. Various operating conditions are investigated and results show that 90% of the lithium in initial Li2SO4 solution can be converted to aqueous LiOH in a one-step precipitation process and the final LiOH.H2O product is determined to have over 99.5% purity. Additional steps including product washing and carbonation are also proposed to improve the lithium conversion and product purity. The by-product barium sulfate (BaSO4) has high market value and can be used in many applications. This process has simple operating procedure, low capital and energy cost and can achieve high product yield and battery grade purity in one batch of reaction without complicated procedures.
Bionanominig: A Revised Insight into Processing of South Africa’s Complex Gold Ores: Daniel Okanigbe1; 1Tshwane University of Technology
South Africa's economy is built on gold mining, the sector is an important foreign exchange earner, with gold accounting for more than one-third of exports. But due to decrease in high grade gold ores, the need therefore arises to investigate ground-breaking approaches for sustainable pretreatment of complex gold ores (CGO). Despite CGOs mineral composition (MC) assisting in figuring out their responsiveness to conventional treatment processes, the challenge of low degree of liberation remains. Hence, this paper presented a revised insight into pre-treatment methods for enhanced liberation and recovery of gold from CGO in South Africa. This aim was achieved by reviewing publications on the different pretreatment methods. It was concluded that it is important to develop cost-effective pretreatment method or combination of methods depending on MC of CGO for low cost and higher gold recovery rates in order to guarantee a sustainable gold industry in South Africa.
Extraction of Rare Earth Metals from Coal Ash Using Mild Lixiviants in a Single Step Process: Riya Banerjee1; Saswati Chakladar1; Sanchita Chakravarty1; 1CSIR-National Metallurgical Laboratory
The redemption of Rare Earth Elements from coal ash has multifarious advantages in utilization of waste and also as a way to minimize unnecessary mining. There is a significant escalation in the quantity of coal ash production, as well as the need of REE in modern day advanced technological products. Utilization of coal ash, knowing its REE enrichment, has been a persistent area of research and development. Our approach is to extract REEs from coal ash in a non-destructive way utilizing least quantity of relatively eco-friendly lixiviant. The novelty lies in efficient and selective leaching of REE using milder and less corrosive reagents compared to mineral acids. Our research group is currently engaged in exploring the leaching potential and kinetics of novel organic lixiviants which can leach REEs (~60-70%) using lower quantities (2-10%), preferably in a single step. Interesting findings from our experimental work will be discussed.
Rare Earth Elements Adsorption to Gypsum in Hydrometallurgical Processes: Farzaneh Sadri1; Ahmad Ghahreman1; 1Queen's University
There has been an increasing demand on the REE supply in the last few decades and a special attention has been directed towards the extraction process of these elements. The impurity removal step is a key step in the processing circuit as it can determine the purity of the final product. Lime neutralization is deemed a preferred process due to its high efficiency in the removal of impurities and low reagent cost. However, some drawbacks such as coprecipitation of REE with calcium sulfate dihydrate (CaSO4 2H2O, CSD), which results in a significant REE loss, renders this process inefficient. In this study, the mechanism of REE co-precipitation with gypsum as well as the effect of two main impurities (Fe and Al), on the REE uptake from the pregnant leach solutions, during the impurity removal step are discussed.
Electrochemical Reduction of Iron Oxides in Aqueous NaOH Electrolyte Including Iron Residue from Nickel and Zinc Electrowinning Processes: Geir-Martin Haarberg1; Bo Qin1; Babak Khalaghi2; 1Norwegian University of Science & Technology; 2SINTEF Norlab
Experiments were carried out in NaOH-H2O (50-50 wt%) electrolyte with a suspension of Fe2O3 particles at ~100 o C. A rotating disk electrode of graphite or silver was used as the cathode. The current efficiency for iron deposition was consistently higher than 90 %. Recent experiments were carried out by using iron containing residue from industrial electrolysis processes for producing nickel and zinc. The challenge is to purify the residue before electrolysis.
Extraction Behaviors of Vanadium(V) with Unacidified- and Acidified-N1923 from a Real Leachate of Vanadium-titanomagnetite: Liu Lei1; Liu Zhaobo2; Pu Nianwen1; Fu Yunfeng2; Zhang Zhongyu1; Du Shangchao2; Du Guoshan2; Sun Ninglei2; Wang Dehua2; Li Xiaoyan2; 1Sichuan Xingming Energy and Environmental Protection Technology Co., Ltd.; 2China ENFI Engineering Corporation
Recently, vanadium extraction has received special attention owing to the application of vanadium in the energy storage. In this study, a vanadium-containing leachate obtained from vanadium-titanomagnetite was employed for the solvent extraction. The primary amine N1923 is selected for vanadium recovery from the feed solution with a high vanadium concentration of 29.21 g/L. The effects of initial pH of feed solution on the vanadium extraction with unacidified N1923 and HCl acidified N1923 are first investigated, respectively. Subsequently, the vanadium extraction performance by HNO3 acidified N1923 is presented. Furthermore, the comparative analysis of vanadium stripping by NaOH from both loaded HCl and HNO3 acidified N1923 is also presented. These experimental results provide a significant reference for the vanadium extraction by N1923 in the industrial production.
Study on Pre–removal Antimony from Antimony–gold Concentrate Using Slurry Electrolysis: Yonglu Zhang1; Chengyan Wang1; Xiaowu Jie2; Wei Gao2; Shufeng Ruan2; 1School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing; 2BGRIMM Technology Group
Antimony has a negative effect on the gold extraction from antimony–gold concentrate, and it is necessary to remove antimony in advance. For a high calcium low antimony gold concentrate (Ca–Sb–Au ore), this study proposed to pre–remove antimony using slurry electrolysis in HCl–CaCl2 system. The results indicated that the optimal conditions were: CaCl2 300~350 g/L, electric quantity 1.2 times, HCl 30 g/L, time 3.5 h, and temperature 60 ℃. The leaching efficiency of antimony and calcium was higher than 96% and 98%, respectively, and gold was less than 1%. The dissolved antimony can be directly electrodeposited on the cathode to produce metallic antimony, the sulfur present in stibnite was transformed into elemental sulfur remaining in the residue, and the leaching residue can be used as raw material for further gold extraction. Thus, the separation of antimony and gold was achieved.
CO2 Optimized Recovery of Special Metals from Precipitation Residue by Selective Chlorination: Stefan Steinlechner1; Lukas Hoeber1; 1Montanuniversitat Leoben
Millions of tons of iron precipitation residues, predominantly jarosite, are accumulating in the primary zinc- or primary precious metals industry every year. Regardless of environmental concerns the material is land filled in almost any case, although valuables such as indium, silver, gold , nickel or zinc are present in considerable amounts. Within the presented research CO2-optimized multi-metal recovery from the residues jarosite by means of a selective chlorination extraction has been evaluated by executed experiments but also by a multidimensional simulation of possible process parameters, utilizing a python algorithm in combination with automated FactSage process step simulation. This allows a simultaneous iteration of relevant reaction parameters such as temperature, pressure, stoichiometry, or variation of additives and with this offers a high degree of freedom in the choice of evaluated reactants. The paper will outline a selection of possibly recovered special metals and the best choice of additives and process parameters.
Novel Environmentally Friendly Leaching Process for Vanadium and Tungsten Recovery from Spent SCR Catalyst: Jong Hyuk Jeon1; Ana Belen Cueva Sola2; Rajesh Kumar Jyothi1; Jin-Young Lee1; 1Korea Institute of Geoscience and Mineral Resources; 2University of Science and Technology
Selective catalytic reduction (SCR) is the best technology to reduce the nitrogen oxides (NOx) emissions in industries. Due to the increasing demand and the limited lifespan of them, after deactivation, they usually end up in landfills posing a major environmental issue. Most catalysts for stationary applications contain around 0.5-1.5% wt V2O5 and 7-10% wt of WO3 in a TiO2 glass fiber matrix and considering the necessity of replacing primary with secondary sources makes the recovery of vanadium and tungsten a major motivation for this research. During this investigation, spent SCR catalyst soda roasting process with dissolved NaOH compared with the traditional NaOH dry roasting and its influence in the subsequent water leaching was studied. With the ideal parameters obtained after optimization there is a reduction of roasting temperature, leaching time and the amount of silicon impurities leached alongside the title metals.
Extraction for Neodymium from NdFeB Magnet Using Supercritical Carbon Dioxide and Organophosphorus Ligands: Nattanai Kunanusont1; Jiakai Zhang2; Yusuke Shimoyama1; Gisele Azimi2; 1Tokyo Institute of Technology; 2University of Toronto
Supercritical carbon dioxide (sc-CO2) is an emerging green solvent for recovery of metals from secondary sources. The sc-CO2 is a non-polar solvent; thus, a suitable chelating agent is required to accommodate a polarity difference between the solute and solvent during the extraction of metal ions and organometallic compounds. This study investigates four different organophosphorus ligands including triethyl phosphate (TEP), tri-n-butyl phosphate (TBP), tributyl phosphine oxide (TBPO), and trioctyl phosphine oxide (TOPO), on the solubility and effect on extraction for neodymium from NdFeB magnet in sc-CO2. A COSMO-vac model was developed to estimate solubility of the four agents in sc-CO2, and it shows that the order of solubility is following: TEP > TBPO ~ TBP > TOPO. The coordination environment of neodymium was determined by UV-Vis measurement, resulting a TEP:Nd = 1, TBP:Nd = 3, TBPO:Nd = 3, and TOPO:Nd = 4. The highest extraction for neodymium is achieved with TEP, which is due to low coordination number resulting less hydrophobic interactions between aliphatic functionalities, and the smaller micellar assemblies has a higher solubility in sc-CO2; thus, a higher extraction efficiency is achieved.
Extraction of Cerium, Lanthanum, and Neodymium from Alluvial Gold Mining Waste from the Bagre-Nechí Mining District in Colombia: Luver Echeverry1; 1Universidad de Nacional de Colombia
In this work, the extraction efficiency of the elements Ce, La and Nd from monazite found in waste from alluvial gold mining was studied. In this sense, the monazite was concentrated through consecutive gravimetric, magnetic, and electrostatic separation processes for its subsequent dephosphorization treatment. The highest extraction of rare earths was achieved with H2SO4 as a leaching medium against HCl in all the concentration, time and temperature conditions evaluated. It was found that the addition of of H2O2 increases the dissolution of rare earths up to 93% in H2SO4 medium. Thermodynamic analysis indicates that H2SO4 solutions have a greater capacity to solubilize REE compared to HCl solutions, supporting the experimental results. Rare earths in sulfuric acid liquor can be recovered to ~100% by precipitation with oxalic acid, the oxalate precipitate obtained was calcined. The final product was characterized by XRD obtaining a composition of CeO2, La2O3 and Nd2O3.
Development of Antagonistic Solvent Extraction Systems for Selective Separation of Copper, Cobalt and Nickel in Ammoniacal Solution: Kurniawan Kurniawan1; Jae-chun Lee2; Jonghyun Kim1; Ha Bich Trinh3; Sookyung Kim2; 1Korea University of Science and Technology, Resources Recycling, KIGAM campus; 2Korea Institute of Geoscience and Mineral Resources (KIGAM); 3Kangwon National University
Selective separation of copper, cobalt and nickel from ammonical solution using antagonistic solvent extraction (SX) systems has been developed. Copper was first selectively extracted using a combination of LIX 84-I and TBP. Subsequently, cobalt was separated from nickel using a combination of PC88A and Alamine 336. Effects of parameters that were investigated include the total ammonia, initial metal concentration, extractants molar ratio, total extractant concentration and phase ratio. The results show that antagonistic interaction of each combination was suitable for selective separation of copper and cobalt, leaving nickel in the ammoniacal solution for further processing. The two-stage antagonistic SX method is simple and promising for further appropriate treatment steps, and can be regarded as the basis for a sustainable metal separation process.
Fundamental Study of a Novel Electrolytic Process Using a Cu Cathode in MgF2–LiF–KCl Molten Salt for Producing Mg Metal from MgO: Hyeong-Jun Jeoung1; Tae-Hyuk Lee1; Kyung-Woo Yi2; Jin-Young Lee1; Young Min Kim3; Toru H. Okabe4; Jungshin Kang1; 1Korea Institute of Geoscience and Mineral Resources; 2Seoul National University; 3Korea Institute of Materials Science; 4The University of Tokyo
In this study, a fundamental study on the molten salt electrolysis of MgO using a Cu cathode was investigated. The influence of the electrolysis temperature, the concentration of Mg in the Mg alloy, the size of the Cu pellets, and the cathodic current density on the current efficiency was investigated. The reaction between an alumina crucible and Mg alloy contained in the crucible was also analyzed. A current of 1.42–2.15 A was applied to the electrolysis cell using a Cu cathode and a carbon anode at 1043–1173 K for 9.5–27.5 h. The average cell potential and current efficiency were 2.28–2.36 V and 88.1–92.0 %, respectively, under certain conditions. When 13.6–14.2 mass% of Mg was electrodeposited, Mg alloys of Cu2Mg and Cu (Mg) mixtures were obtained. Therefore, the novel electrolytic process is an effective method for Mg metal production.