REWAS 2022: Recovering the Unrecoverable: On-Demand Oral Presentations
Sponsored by: TMS Extraction and Processing Division, TMS: Recycling and Environmental Technologies Committee, TMS: Hydrometallurgy and Electrometallurgy Committee
Program Organizers: Mertol Gokelma, Izmir Institute of Technology; Elsa Olivetti, Massachusetts Institute of Technology; Camille Fleuriault, Eramet Norway; John Howarter, Purdue University; Takanari Ouchi, University of Tokyo; Gisele Azimi, University of Toronto; Kerstin Forsberg, KTH Royal Institute of Technology; Hong (Marco) Peng, University of Queensland; Kaka Ma, Colorado State University

Monday 8:00 AM
March 14, 2022
Room: Energy & Environment (including REWAS 2022 Symposia)
Location: On-Demand Room

Recent Trend on the Studies of Recycling Technologies of Rare Earth Metals: Osamu Takeda1; Xin Lu1; Hongmin Zhu1; 1Tohoku University
    There is uncertainty in the supply of rare earth resources. Technical developments on the resource saving of rare earths and the alternate materials are important challenges, and the development of recycling technologies is also important for securing stable supply of rare earth resources. This presentation focuses on the recycling of the waste of neodymium magnet that is the industrially important product containing rare earth metals. Recent trend on research and development of recycling technologies of rare earth metals will be briefly reviewed. The research conducted by the authors, particularly the development of pyrometallurgical processes for recycling, will be also introduced.

Recycling of Tungsten by Molten Salt Processes: Tetsuo Oishi1; 1Aist
    Tungsten(W) is one of the most important metals in various industries, especially in the machining industries. At least 60% of W is consumed in cemented carbide or super hard alloy in Japan and the US. Most major recycling method for cemented carbides is the hydrometallurgical process combined with the roasting step, which oxidizes W in the scrap into tungsten oxide. On the other hand, molten salt process has certain advantages in terms of processing rate, simplicity and so on. In this presentation, recycling processes for W using molten salt will be reviewed. After that, our new recycling process using molten hydroxide will be introduced and the recent progress on this process will be discussed.

Recycling Technologies Developed at KIGAM: Jin-Young Lee1; Kyeong Woo Chung1; Hong-In Kim1; SooKyung Kim1; Shun Myung Shin1; Ho-Seok Jeon1; 1Korea Institute of Geoscience and Mineral Resources
    KIGAM, which is a unique government-funded Geoscience research organization in Korea, has researched and devised many technologies on mineral processing and extractive metallurgy for more than 70 years. In addition, several recycling processes have much studied from lab scale to pilot plant scale for the last two decades, and many technologies for the recycling of secondary resources such as Lithium batteries, Neodymium magnet, and catalyst etc have been developed based on pyrometallurgy, hydrometallurgy and electrometallurgy. Especially, some of them were already transferred to industry and commercialized in KOREA. In the presentation, details of the recycling technologies at KIGAM will be introduced and discussed.

Setting New Standards for Circular Economy in the Cement Industry: Michael Klitzsch1; Martin Geith1; 1RHI Magnesita
     In the past, recycling of refractory linings from the cement industry has not been possible due to contaminations impregnating the linings during the cement production process. These contaminations lead to production issues and negative effects on the refractoriness when spent material is reused as raw material. RHIM has developed and patented a treatment method to reduce the contamination of spent refractories which technically enables their reuse. Linings based on this technology have a reduced CO2 footprint of up to 20%.However, a business model based on a circular economy requires additional developments to be implemented in the organization. As spent refractory linings are classified as waste, the legal framework of the supply chain must be adapted. A changed supply chain setup enables the sourcing and cross-border shipment of spent refractories. With introduction of products containing recycled material to the market, the perception of these “waste” products must be positively changed.

Recycling of Electronic Wastes, Waste Batteries and Rare Metal Wastes in China: Li Qinxiang1; 1Jingmeng GEM Co., Ltd.
     1) Introduce the basic information of disposal enterprises and disassembly capacity of electronic wastes in China in 2020. And detailed information on the classification,the amount of recycling and dismantling products of GEM in 2020. 2)Summarize the recycling of background, status and technology of spent lithium-ion batteries in China. and present and analyze the advantage and disadvantage of the application of all kinds of industrial scale technologies of spent lithium-ion batteries.3) introduce the classification,treatment technology and the recycling amount of renewable nickel and cobalt resources.

Yellow Phosphorus Production from Phosphoric Acid by Carbothermic Reduction: Huafang Yu1; Ryoko Yoshida2; Yasushi Sasaki1; Tetsuya Nagasaka1; 1Tohoku University; 2DOWA
    Phosphorus is an essential element for agriculture and industry and is a non-renewable resource. High purity yellow phosphorus is always produced from high-grade phosphate ore, however, high-grade phosphate ore deposits are rapidly being depleted and claim that economically available deposits may be completely exhausted with a century. Therefore, producing yellow phosphorus from the secondary resource is an urgent matter. In this research, high purity yellow phosphorus was successfully produced from phosphoric acid extracted from steelmaking slag by carbothermic reduction. In the newly developed system, gaseous P4O10 evaporated from H3PO4 is reduced to yellow phosphorus at less than 1273K. Since our process consumes less energy and has a very low environmental impact compared with the current process, it will be one of the promising solutions to meet the depletion of phosphate ore.

Leaching of Rare Earth Elements from Phosphogypsum Using Mineral Acids: Sicheng Li1; Monu Malik1; Gisele Azimi1; 1University of Toronto
    Rare earth elements (REEs) are critical metals for modern and emerging green technologies. The increasing demand and limited supply of them have sparked the research on the recovery from secondary resources. The current study is focused on developing a hydrometallurgical process for the extraction of critical REEs from waste product from fertilizer manufacture (phosphogypsum, PG), and on elucidating the mechanism of the process. Three types of mineral acids are used for the leaching, and systematic study is utilized to assess the effect of operating parameters and to determine the optimum operating conditions. The thermodynamic modeling and solubility investigation show the strong correlation between phosphogypsum solubility and leaching efficiency, and the mechanism behind the leaching process is explored. Characterization results indicate that the REEs can exist as isomorphous substitutions and/or separate phases inside PG crystal. Based on these results, destruction of PG lattice and dissolution is required to achieve improved extraction.

Recovery of Terbium, Europium, and Yttrium from Waste Fluorescent Lamp Using Supercritical Fluid Extraction: Jiakai Zhang1; John Anawati1; Gisele Azimi1; 1University of Toronto
    Recycling of waste electrical and electronic equipment (WEEE) has been receiving significant attention around the world. Here, we develop an environmentally sustainable process that uses supercritical carbon dioxide as the solvent along with a small volume of tributyl-phosphate (TBP) nitric acid adduct as the chelating agent to recover rare earth elements (REEs) from fluorescent lamp waste. We show that mechanical activation using oscillation milling increases extraction efficiency. We elucidate the process mechanism by characterizing the solids before and after the process using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). We show that Al3+ and Ca2+ cations from the Al2O3 and Ca5(PO4)3OH (hydroxyapatite) present in the fluorescent lamp waste result in competing reactions with REEs with TBP-HNO3 adduct; thus, REE extractions from real fluorescent lamp waste is less than what has been reported from synthetic feeds. Management of fluorescent lamp waste leads to sustainability of biosphere and circular economy.

Characterization and Thermal Treatment of Eggshell and Olive Stones for Heavy Metals Removal in Mining Environmental Liabilities Sites: Mery Gomez-Marroquin1; Henry Colorado2; Dalia Carbonel-Ramos3; Jhony Huarcaya-Nina3; Stephany Esquivel-Lorenzo3; Alfredo Ceroni-Galloso3; Hugo Chirinos-Collantes3; 1FIGMM UNI; 2University of Antioquia - UDEA; 3FIA UNI
     This paper presents the results of characterization, thermal, and chemical treatments made over natural eggshells (ES) and olive stones (OS) samples. The main goal was to perform an analysis to assess the potential of treated ES and OS to remediate heavy metals from polluted soils with mining tailings (PSMT). Sample powders of ES, OS, and PSMT were mechanically treated and characterized with chemical analysis, X-Ray Diffraction, Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric, and Differential Thermogravimetric techniques (TGA & DTG). ES was subjected to a calcination test. OS samples were thermally treated and chemically modified with thiol. PSMT was characterized using specific gravity, average particle size, and environmental indicators. FT-IR analysis indicated the presence of CaCO3, Li2CO3, K2CO3, and KNO3 functional groups in ES and OS. The XRD analysis of ES samples showed the presence of one mineralogical phase (CaCO3). Diffraction patterns in the OS could not be identified due the amorphous condition of the sample. ES calcination tests presented a mass loss near 47% (w/w). The process to obtain chemically modified pre-oxidized biochar from OS reported pyrolysis mass loss of 80.59%, pre-oxidized mass loss of 35.43%, and an addition of 0.14g during the chemical treatment. Equilibrium diagrams showed that Cd+2 and Hg+2 are most likely in the PSMT soil solution (aqueous phase), whose cations could be removed via cation exchange of the calcinated ES. The mercaptoethanol content in the chemically modified pre-oxidized biochar could be effective in removing the Hg content in PSMT.Keywords: EEggshell, Olive stones, Calcination, Thermal treatment, Chemical modified, Agricultural Recycling, Environmental effects, Processing Extraction, Secondary Recovery

Characterization and Thermal Treatment of Electric Arc Furnace Dusts Generated during Steel Production in Peruvian Industries: Mery Gomez-Marroquin1; Jose Carlos D´Abreu2; Roberto de Avillez2; Sonia Letichevsky2; Kim Phatti - Satto1; Abraham Terrones - Ramirez1; 1FIGMM UNI; 2PUC-Rio
     Self-reduction is a pyrometallurgical treating process which aims to valuable metal recovery from mining-metallurgical industry wastes, mainly from steelmaking industries. Electric Arc Furnace Dusts (EAFD) are still the most attractive materials to be tested in using this technique, due to their high magnetite and franklinite/zinc ferrite contents. This research will address the reuse of these co-products in steel plants, providing added value to this material that until now is constituted as an environmental liability of considerable economic importance in steelmaking industries. Chemical and microstructural analysis have determined high contents of iron and zinc from magnetite and franklinite/zinc ferrite. Iron was present in the non-stoichiometric form of “hapkeite” (Fe1.34Si0.06) in both EAFD 1 and EAFD 2. A rare appearance of Moissanite CSi –2H was also found in EAFD 1. Thermogravimetric evaluations allowed elimination of almost 15 % of volatile matter at 1000 °C in EAFD 1. EAFDs were partially reduced and showed a high porosity, which would make it possible for the recovery of its main metal content by carbothermic self-reduction. Proximate analysis, and carbon dioxide reactivity of two reductants were tested for evaluating the behavior of selected reductants in carbothermic self-reduction of EAFDs using a procedure given by the Steelmaking and Ironmaking Group of DEQM PUC/RJ. This mixture included 85% (EAFD + coal), 6% CPV ARI, and 9% water. Operational Diagram of Phase Predominance (ODPP) from the Zn-Fe-C-O system was used to calculate the required carbon and to guarantee the occurrence of the global chemical reactions of carbothermic reduction either in franklinite/zinc ferrite as in magnetite by 100% CO, and temperatures between 1000°C to 1100°C. In these conditions, self-reducing briquettes of EADF 2 lost more weight so reacted faster than EAFD 1. Finally, reactions rates of carbothermic self-reducing briquettes EAFDs were very fast during the first 5 minutes and retarded from 5 to 40 minutes.Keywords: Self-reduction, Carbothermic reduction, Electric Arc Furnace Dusts-EAFD, Steelmaking residues, Processing & Extraction, Environment effects, Recycling & Secondary Recovery

Utilization of Copper Nickel Sulfide Mine Tailings for CO2 Sequestration and Enhanced Nickel Sulfidization: Fei Wang1; David Dreisinger1; Glenn Barr2; 1The University of British Columbia; 2Twin Metals Minnesota LLC
    Global warming mitigation is carrying out under two strategies of reducing CO2 emissions and encouraging battery-powered electrical vehicles. Enhancing nickel sulfide production is significant to increase battery supply. Nickel in olivine which is an important mineral of many nickel sulfide mines and suitable for permanent CO2 sequestration, is regarded as non-recoverable and discarded in mine tailings as wastes. This work confirms that a copper nickel sulfide flotation mine tailing in Minnesota as a case study can be used for directly accelerated mineral carbonation and concurrent sulifidization. In addition to converting magnesium and iron silicates to mineral carbonates for permanent CO2 storage, nickel in olivine is concurrently converted to nickel sulfide for potential recovery. The mineral carbonation of olivine is the dominant chemical reaction process and provides the precondition for nickel sulfidization. A pre-concentration step of olivine from tailings is recommended to enrich olivine and nickel contents for potential application.

Extraction of Nickel from Recycled Lithium-ion Batteries: Meng Shi1; Sabrina Reich2; Ankit Verma3; John Klaehn1; Luis Diaz1; Tedd Lister1; 1Idaho National Laboratory; 2Michigan State University; 3University of Kansas
     Aiming to recover critical materials from waste batteries, we have developed a series of operations to extract individual metals from the end-of life solid mixture based on their electrochemical (EC) and chemical properties. Our large-scale EC-leaching process isolates graphite and metallic copper by electricity, and generates a leachate solution of metals.[1] This leachate can contain aluminum and iron that are removed by pretreatment processes. Then, the remaining critical metals can be individually extracted through other extraction operations, including solvent extraction, ion-exchange, precipitation, and electrochemical dialysis. Through these methods, we have successfully developed a feasible and flexible recovery of critical materials and high purity metal salts from recycled waste lithium-ion battery materials.1. Diaz, L.A., et al., Electrochemical-assisted leaching of active materials from lithium ion batteries. Resources, Conservation and Recycling, 2020. 161: p. 104900.

Recovery of Precious Metal Silver from Scrap Computer Keyboards: Rekha Panda1; Om Shankar Dinkar1; Pankaj Kumar Choubey1; Rukshana Parween1; Manis Kumar Jha1; Devendra Deo Pathak2; 1CSIR-National Metallurgical Laboratory, INDIA; 2Indian Institute of Technology (ISM) Dhanbad, INDIA
    Silver (Ag) is extensively used in manufacturing of electronic goods due to its low-cost and conductivity. In view of the escalating demand, stringent environmental rules and limited primary sources of Ag, present paper is focused on the development of hydrometallurgical process flow-sheet to extract Ag from scrap computer keyboards. These keyboards contain ~0.4% Ag. Initially, scrap keyboards were dismantled to separate the Mylar sheet containing Ag. The same was pyrolysed at 300 °C for 2 h to get enriched metallic part (~2%). About 99.99% Ag was leached using 2 M HNO3 at 60 °C within 30 min in closed and proper condensed system. Separation techniques (precipitation/ cementation) could be use to obtain high purity Ag salt/ metal. Based on the laboratory scale experiments, the process flow-sheet developed is economical, eco-friendly and has potential to be translated to industry for commercial exploitation after scale up/ pilot trial.

Efficient Steel Mill Dust Recycling – Aiming For Zero Waste: Juergen Antrekowitsch1; 1University of Leoben
     Steel mill dust recycling today is an important business. However, most processes in operation hardly fulfil future requirements from the environmental point of view. In general, these treatment facilities show a certain CO2-footprint due to carbothermal reduction and produce high amounts of residues which often have to be landfilled. The paper discusses possibilities to optimize state of the art processes regarding the realization of a zero waste strategy and the minimization of the CO2-footprint. Furthermore, new developments are evaluated in respect of energy consumptions and environmental awareness. As an example the “2-step-Dust-Recycling” process, an own development of the University of Leoben in Austria, is analyzed regarding its potential to meet requirements of present and future environmental legislation.Finally, the way how different options of steel dust treatment influence the overall zinc cycle, especially the role of zinc oxide from such sources as substitute for primary concentrates, is described.

Deoxidation of Titanium Using Cerium Metal and Its Oxyhalide Formation: Gen Kamimura1; Takanari Ouchi1; Toru Okabe1; 1The University of Tokyo
    Recycling of titanium (Ti) scraps requires the direct removal of oxygen (O) from the Ti scraps. Many deoxidation techniques for Ti have been developed; however, the strong affinity between Ti and O has limited their cost-effectiveness. In this study, we developed a new deoxidation process for Ti using cerium (Ce) metal, which is the most abundant and the lowest-price rare earth element. The thermodynamic analysis suggests that the deoxidation through the formation of Ce oxyhalides in halide fluxes containing Ce ions can produce Ti with extremely low O concentration. We experimentally demonstrated that the formation reaction of CeOCl with Ce metal can deoxidize Ti metal and produce highly pure Ti with 100 mass ppm O or below, which is lower than the O concentration of the virgin Ti produced through the Kroll process. This deoxidation process with Ce metal enables Ti scraps contaminated with O to be recycled.

Estimation of the Generation and Value Recovery from E-waste Printed Circuit Boards: Bangladesh Case Study: Md Khairul Islam1; Nawshad Haque2; Michael Somerville2; Mark Pownceby2; Suresh Bhargava1; James Tardio1; 1Royal Melbourne Institute of Technology; 2CSIRO
    This article analyses Bangladesh export-import data to quantify historically generated e-waste from four types of discarded electronic devices (mobile phones, TVs, tablets, computers/laptops) and uses the trends to predict the generation of e- waste from these devices up to 2030. From this data, together with estimated redundancy rates, printed circuit board (PCB) masses, metal content and value based on characterisation of indicative samples, the potential value of e-waste was evaluated. Through processing the PCBs in Bangladesh, metals including Cu, Ag, Au, Pd and Sn, worth more than US$2.4 billion till 2020 could be recovered. This value could reach US$7 billion when forecasted to 2030. The potential value varies mainly with the fluctuating metal prices in the international market.

A Green Process to Acquire a High Purity Rare Earth Elements Leach Liquor from Nd-Fe-B Magnets by Caustic Digestion and Roasting Processes: Rina Kim1; Kyeong Woo Chung1; Ho-Sung Yoon1; Chul-Joo Kim1; Yujin Park1; 1Korea Institute of Geoscience and Mineral Resources (KIGAM)
    To recover rare earth elements (REEs) from Nd-Fe-B magnets, a variety of hydrometallurgical processes have been developed, and among them, caustic digestion-acid leaching is the most promising. Through the caustic digestion, Nd and Fe in the magnet alloy could be converted into Nd(OH)3 and Fe3O4, respectively, and they were easily recovered in the following acid leaching step. To remove iron from REE leach liquor, it was essential to precipitate iron after the acid leaching, and it consumed an amount of chemical like lime. So, to solve the aforementioned problem, a new green process was developed, lowering iron content in leach liquor; through an oxidative roasting of the digested product prior to the acid leaching, iron dissolution was considerably decreased. The digested powder was roasted at 350-450˚C, and the product was leached in 0.5 M HCl. The final leach liquor contained ca. 17 g/L Nd and ca. 330mg/L Fe.

An Innovative Separation Process for Spent Lithium-ion Battery Using Three-stage Electrodialysis: Ka Ho Chan1; Monu Malik1; Gisele Azimi1; 1University of Toronto
    An innovative electrochemical process to separate lithium, nickel, manganese, and cobalt using a three-stage electrodialysis with the addition of ethylenediaminetetraacetic acid (EDTA) is proposed. Before the electrodialysis experiment, ultraviolet-visible spectroscopy is used to study the complexation behavior of EDTA with four different metals. During the electrodialysis experiment, a synthetic solution mixed with a stoichiometric ratio of EDTA to the target metal is supplied to a lab-scale electrodialysis stack, in which nickel is separated in the first stage, cobalt is separated in the second stage, and manganese is separated from lithium in the third stage. The results reveal that the concept of separating four different metals in a multi-metallic system using the three-stage electrodialysis is feasible, which could be potentially implemented in other industries that involve the waste valorization of critical metals.

Development of Technology for Recycling Large-capacity Lithium-ion Batteries for EV,ESS: Hongin Kim1; Jeong-Soo Sohn2; Soo-Kyung Kim2; Dong-hyo Yang2; Suk-hyun Byun3; 1KIGAM/Convergence Research Center for DMR; 2KIGAM/Mineral Resource Division; 3SungEel HiTech.
     The lithium-ion batteries used in electric vehicle are composed of one pack. This pack is composed of several modules and each module is composed of several cells. The weight of battery pack is above 400 kg but the weight percent of cell is only 60%. The other 40% is not lithium-ion cells but another components such as BMS(battery management system), PRA(power relay assembly), safety plug, cable, cooling system and pack case. Recycling technologies for valuable metals such as cobalt, nickel, manganese and lithium are now commercialized but non-battery components in battery pack of electric vehicles are not fully recycled. In order to complete the recycling of spent battery pack in electric vehicles, recycling of non-battery components is necessary in addition to lithium-ion cell recycling. So in this study, we introduced the physical treatment processes such as dismantlement, crushing, grinding, magnetic separation and size separation for non-battery components recycling.

Recovery of Molybdenum from Metallurgical Wastewater by Fe(III) Coagulation and Precipitation Flotation Process: Bei Zhang1; Bingbing Liu1; Yanfang Huang1; Guihong Han1; Yifan Du1; Shengpeng Su1; 1Zhengzhou University
    Molybdenum (Mo) is an irreplaceable alloying element of steel, resulting in the vigorous development of Mo metallurgy industry. However, abundant Mo-bearing wastewater with low concentrations are concomitantly generated, which is difficult to recycle, resulting in a waste of resources. In this work, recovery of Mo from metallurgical wastewater by Fe(III) chelation and precipitation flotation process was investigated. The effects of pH value, Fe(III) and HA dosage, reaction time on the Mo recovery efficiency from wastewater were systematically studied. The results showed that the molybdate in the solution can be coagulated by Fe(III) to form precipitation. HA can effectively increase the sizes of precipitation particles and improve flotation separation of Mo. After optimization, over 99.6 % Mo are removed under the optimal coagulation and flotation condition. This technology can realize the effective recovery of molybdate from wastewater.

Treatment of Benzohydroxamic Acid Wastewater by Fe(III) as Chelator Precipitation Flotation Process: Yifan Du1; Guihong Han1; Yanfang Huang1; Bingbing Liu1; Wenjuan Wang1; Bei Zhang1; 1Zhengzhou University
    Benzoximic acid (BHA) is a commonly used collector in mineral processing industry. The accumulation of BHA in water will cause serious damage to environment. Therefore, how to efficiently treat the residual BHA in mineral processing wastewater is an important issue in the mineral processing industry. In this study, Fe(III) was used as chelating agent to separate BHA from wastewater by precipitation flotation. The optimum flotation conditions of BHA and Fe(III) were obtained by optimizing the chelation and flotation processes. The results showed that the chelating efficiency was the highest when the chelating pH was 7 and Fe(III) was 40mg/L.. When the addition amount of surfactant CTAB is 4mg/L and the gas flow rate is 40mL/min, the flotation removal rate of BHA reaches 90%, and the COD removal rate of the solution is 73%.The treated solution reaches the first class standard of industrial waste water discharge.

Maximizing the Efficiency of By-product Treatment by Multi Metal Recovery and Slag Valorization: Gustav Hanke1; Jürgen Antrekowitsch1; Fernando Castro2; Helmut Krug3; 1Montanuniversität Leoben; 2University of Minho; 3R+M Ressourcen + Management GmbH
    Complete utilization of every material mined seems to be a highly obvious strategy to save natural resources and avoid residues to be dumped. In fact, examples where this is practiced are very limited. Often residues out of metal production are not fully exploited and contain still considerable amounts of various valuable elements when being dumped. Using the full potential of mined material would significantly support the metal supply, while optimizing the CO2 balance, as much of the afford of winning a metal is already done, especially the mining. Not only the CO2 footprint, but also the avoidance of residues is an omnipresent topic nowadays. Pyrometallurgical treatment is unavoidably linked to slags. Regarding a zero-waste solution, these slags have high potential to be used as construction materials. Referring to this, zero-waste solutions for residues from primary zinc and lead production were tested, emphasizing the potential of this strategy.