Technical Sessions

 

The 9th International Symposium on Hydrometallurgy brings you many aspects of metallurgical processing including mineral processing, extractive metallurgy, environmental science and engineering, as well as its future role in processing base metals, precious metals, and strategic metals and minerals.

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Environment/Waste Treatment

Assessing the Suitability of Mine Tailings as a Geopolymer Precursor Material for Subsurface Engineered Barriers for In-Situ Recovery Operations

Godfrey Mawire, Curtin University, Commonwealth Scientific and Industrial Research Organisation; Robbie McDonald, Commonwealth Scientific and Industrial Research Organisation; Lionel Esteban Commonwealth Scientific and Industrial Research Organisation; Abhijit Mukherjee, Curtin University; Navdeep Dhami, Curtin University

Introducing artificial barriers to contain lixiviants within in-situ recovery operations is critical for economic and environmental reasons. Geopolymers which offer high acid resistance and rapid strength development were investigated as barrier materials. A range of mix designs were used to study tailings from two sites, CMT1 and CMT2. The reaction stages were quantitatively analysed with isothermal calorimetry. Under representative of subsurface pressure and temperature conditions, all permeability measurements were made at 3.5 MPa confining pressure (or 1.72 MPa effective pressure) and 22ºC; and converted into apparent hydraulic conductivity assuming water physical properties at the subsurface pressure and temperature conditions. The best hydraulic conductivity was found at 2.74×10-11 m/s for CMT1 and 3.62×10-11 m/s for CMT2 corresponding to a period ~ 1150 and 875 years respectively to displace lixiviants through 1-meter of such artificial barrier.

 

Sustainable Water Recovery from Hydrometallurgical Effluents Using Gas Hydrate Based Desalination

Seyed Mohammad Montazeri, Department of Mining, Metallurgical, and Materials Engineering, Université Laval, Québec, Québec, Canada; Georgios Kolliopoulos, Department of Mining, Metallurgical, and Materia ls Engineering, Université Laval, Québec, Québec, Canada

Hydrometallurgical processes generate large volumes of aqueous effluents. These effluents are deposited in tailings ponds, after being treated to remove impurities and recover water for reuse in process circuits. Effluent desalination is key to attain a zero liquid discharge future in the industry. In this study, we report on hydrate based desalination (HBD), which is an innovative, energy-efficient, and sustainable desalination technology, capable to treat hydrometallurgical effluents to recover water in the form of gas hydrates by consuming CO2, which is a harmful greenhouse gas. Therefore, HBD meets the criteria of an eco-friendly effluent treatment technology, especially compared to conventional methods.

 

In Pursuit of Zero Discharge: Forward Osmosis and Freeze Concentration for Hydrometallurgical Wastewater Recycling

Noel Devaere, University of Toronto; Vladimiros Papangelakis, University of Toronto

To address the growing need for improved water capture for recycling in the hydrometallurgical industry, we are developing a hybrid process to treat aqueous wastes and intermediate streams by Forward Osmosis (FO) and Freeze Concentration (FC). The proposed FO-FC process has energy advantages over traditional precipitation and evaporative technologies, particularly for cold climates. This work describes the FO-FC proof-of-concept results and developments to date.

 

Materials for Clean Energy

The Atlas Materials Process for Carbon Negative Nickel and Cobalt Recovery from Laterites

David Dreisinger, Atlas Materials Co;  Jeremy Ley, Atlas Materials Co; Mike Johnson, SGS Canada Inc.; Niels Verbaan, SGS Canada Inc.; Sridevi Thomas, SGS Canada

Atlas Materials has developed a process for extraction of nickel and cobalt from saprolite ores to meet the growing demand for nickel and cobalt salts for lithium-ion battery manufacture to enable the electric vehicle transition in the global transport sector. Saprolite ores are milled in a sodium chloride brine solution and then leached using hydrochloric acid addition. The silica residue from leaching may be used as a supplemental cementitious material. Iron and aluminum are removed by pH adjustment with olivine addition. Nickel and cobalt are precipitated as a mixed hydroxide product. Manganese is removed by oxidation and pH adjustment to form a manganese product (+25% Mn content). Magnesium is precipitated as magnesium hydroxide. The final brine solution is recirculated to leaching or directed to chlor-alkali processing to produce hydrochloric acid and sodium hydroxide. The mixed hydroxide product (MHP) can be converted to high purity nickel sulfate salt for the lithium-ion battery market.

 

Metal Extraction

Evaluating the Use of a Dynamic Model to Predict Direct Copper Electrowinning Tankhouse Performance

Suné Grobbelaar, Department of Chemical Engineering, Stellenbosch University; Christie Dorfling, Department of Chemical Engineering, Stellenbosch University; Margreth Tadie, Department of Chemical Engineering, Stellenbosch University

A dynamic model can be coupled with advanced control strategies to improve the efficiency of tankhouses employing resource-intensive direct copper electrowinning. Consequently, a high-fidelity, dynamic model that captures the complex fundamental chemistry associated with the variable electrolyte composition present in direct copper electrowinning was developed. A self-updating parameter-fitting approach was incorporated to calibrate the model for use on tankhouse-specific data. Validation of the model was performed using industrial electrowinning data. This paper presents the findings, challenges, and opportunities associated with the application of the model to industrial case-study data obtained from a direct copper electrowinning tankhouse.

 

Precious Metals Refinery Transformation – Piloting as a Basis for Success

Christoph Ziegler, Aurubis AG, Hamburg, Germany; Leslie Bryson, Aurubis AG, Hamburg, Germany

Aurubis is considering upgrading its precious metals refinery. Developed internally, the current process is based on a Möbius type silver electrolysis and a combined nitric/chloride gold refining and platinum group metals (PGM) solution production. A future refinery shall be based on a direct chloride leach of the silver anode slimes and a subsequent treatment of the resulting gold/PGM solution and silver chloride residue. For this purpose we developed a full flowsheet based on lab scale results. In this paper we present how we planned, built and operated a pilot plant for this flowsheet. Furthermore, we will discuss the importance of an early definition of scope and success criteria. Finally, the results of the piloting were transformed into process design criteria that are the basis of a feasibility engineering.

 

Optimisation of Silver Electrorefining at Aurubis

Leslie Bryson, Aurubis AG, Hamburg, Germany; Christoph Ziegler, Aurubis AG, Hamburg, Germany

Aurubis is considering the upgrade of its precious metal refinery. Developed and optimized over the years, input to the current process is based on cast silver anodes feeding a Möbius type silver electrolysis section. It has been envisaged that the future refinery shall continue to incorporate a Möbius based silver electrorefinery, however at unprecedented higher PGM contents and operating current densities. These modifications aim at the development of a silver-based Precious Metals refinery with a higher degree of flexibility and lower CAPEX and working capital. In this paper we will discuss these new developments along with the design and operation of a pilot plant used to validate design criteria. These design criteria have been considered in the basis of a feasibility engineering study.

 

Improving the Rate of Recovery from Copper Leach Residue with the Addition of a Wetting Aid: A Metallurgical and Geophysical Study

M.L. Catling, BASF Corporation, Tucson, AZ; R.G. Copp, BASF Corporation, Tucson, AZ; JJ Taute, BASF Corporation, Tucson, AZ; D.F. Rucker, HydroGEOPHYSICS, Inc. Tucson, AZ; B.D. Cubbage, HydroGEOPHYSICS, Inc. Tucson, AZ

Ore grades have been shown to be decreasing globally, forcing more mining operations to increase the annual throughput of ore to maintain metal production targets. A leaching aid has been developed with the goal of increasing the kinetic rate and overall metal recovery in heap-leaching processes. This investigation utilizes electrical resistivity testing to investigate the conductivity of an active leach pad before and after the addition of a leaching aid and discusses the changes observed in the geophysical and metallurgical data following its addition, as well as the implications of those results.

 

Performance Evaluation of Modified Biopolymers as Acid Suppressants in Copper Electrowinning

Marcio Ribeiro, W Tech Technologies Ltd; Peter So, W-Tech Technologies Ltd; Patrick Wong, W-Tech Technologies Ltd

Sulfuric acid mist is released during the electrowinning of copper. Among several techniques applied to suppress acid mist formation, fluoroalkyl based products have been the most chemistry type used worldwide. In this paper, modified biopolymers were tested as alternative surfactants to reduce acid mist in copper electrowinning. Two products, Biopolymer NCB and Biopolymer LB, were tested in laboratory to determine their effects on acid mist suppression. Both products lead to over 90% reduction of sulfuric acid mist with no significant impact on current efficiency. The two products were recommended for a commercial field test.

 

Leaching Metals from Phyllosilicate Ores

Isabel Barton, University of Arizona Department of Mining & Geological Engineering; Maxwell Drexler, Rio Tinto Inc.; Molly Radwany, Freeport-McMoRan Inc.; Pierre Marie Zanetta, Univ Jean Monnet, Saint Etienne, France

Phyllosilicate minerals are important ores of V, Zn, Ni, and sometimes Cu. This paper uses phyllosilicate crystal chemistry, leaching experiments, and transmission electron microscopy to examine metals’ three distinct modes of occurrence and leachability in these ores. (1) Adsorbed metals can be liberated via exchange with solution cations, depending on chemical conditions and phyllosilicate type. (2) Crystallographically contained metals are partially leachable, typically at elevated temperatures, if they are in octahedral or higher coordination. (3) V, Ni, Cu, and possibly other metals, form discrete nanometer-scale inclusions within phyllosilicates whose leachability is mostly controlled by their mineralogy, not the phyllosilicate host’s.

 

High Performance Liquid Chromatography Analytical Method Development for Reduced Sulfur Species Quantification in Cyanide Leach Solutions

N. Duru, University of Nevada, Reno; C. Nesbitt, University of Nevada, Reno

Development of an accurate analytical method for sulfur species in cyanide leaching units of gold ores where sulfur speciation occurs has important role to explain the metal recovery deviations. This study presents the development steps of high-performance liquid chromatography (HPLC) method to analyze reduced sulfur species thiocyanate (SCN-), thiosulfate (S2O32- ), trithionate (S3O62- ), tetrathionate (S4O62-) in cyanide leaching circuits for gold ores. HPLC method developed has resulted in precise quantification of target sulfur species in leach solutions. Method development and validation results were illustrated on analytical graphs contains each species’ peak number, retention time (min), type, width (min), area (mAU*s), height (mAU), area distribution (%) of the peak.

 

Ammonium Thiosulfate Leaching of Gold with Magnesium Hydroxide and Its Effect on the Consumption of Thiosulfate

Sujin Chae, Queen’s University, The Robert M. Buchan Department of Mining, Queen’s University; Farzaneh Sadri, University of Alberta, Department of Chemical and Materials Engineering; Yeonuk Choi, Queen’s University, The Robert M. Buchan Department of Mining, Queen’s University; Ahmad Ghahreman, Queen’s University, The Robert M. Buchan Department of Mining, Queen’s University

Thiosulfate gold leaching is a promising alternative to cyanidation though it still has to be improved due to the significant reagent consumption caused by its decomposition. The purpose of this study is to mitigate thiosulfate consumption. The key to this study is the cycle in which ammonia vaporizes and the lowered pH is restored by the dissolution of magnesium hydroxide. Mg(OH)2, which has low solubility in alkaline solutions, has the potential to benefit gold leaching by preserving a pH that is favorable to gold extraction. In this study, the effects of pH, magnesium, copper, and thiosulfate concentration were evaluated. The test adjustment using NH4OH had higher Au recovery than using Ca(OH)2 though, Ca(OH)2 is still suggested to be an alternative that can reduce the amount of ammonia. Gold concentration increased with 0.01 M of Mg(OH)2, but there was no discernible improvement with further addition. Thiosulfate showed enhanced gold leaching when increasing from 0.5 to 2.0 M. Up to 1.0 mM, copper concentration had a favorable impact on the concentration of au, but after that point, it had the opposite effect. The optimal gold extraction condition in this study was thiosulfate 0.2 M, Mg(OH)2 0.01 M, Cu 1 mM, pH 10.0, leaching 70.5% gold, which is comparable to 66.5% obtained by cyanide leaching.

 

Extraction of Critical Elements from Sulfuric Acid Solutions

Weston C Hartzell, Missouri University of Science and Technology, Rolla, MO; Michael S Moats, Missouri University of Science and Technology, Rolla, MO

To address the supply risk of critical semiconducting materials, sustainable resources need to be developed. A zinc leach residue originating from electric arc furnace dust contains gallium (Ga), germanium (Ge), and indium (In). The residue can be leached with sulfuric acid to extract Ga, Ge, and In into an aqueous solution, however a process is needed to separate and concentrate these elements for recovery. The extraction of these critical elements from sulfuric acid solutions were examined using commercially available solvent extraction extractants and ion exchange resins. Distribution ratios and separation factors of these products are reported. A potential flowsheet to recover these critical electronic elements from a zinc leach residue is presented.

 

Stabilization of Arsenic Byproduct from Decopperization Process to Scorodite Using Methanesulfonic Acid

Junmo Ahn, The Department of Mineral Resources & Energy Engineering, Jeonbuk National University, Jeonju, South Korea; Jiajia Wu, The Department of Mining Geological Engineering, University of Arizona, Tucson, AZ, USA; Jaewoo Ahn, The Department of Advanced Materials Science and Engineering, Daejin University, Pocheon, South Korea; Jaeheon Lee, The Department of Mining Engineering, Colorado School of Mines, Golden, CO, USA

Arsenic (As) is a toxic byproduct from copper smelter. Arsenic immobilization is critical to prevent detrimental impacts on the environment. Arsenic compounds from decopperization requires to be dissolved and stabilized into scorodite. However, conventional lixiviant, H2SO4 limits As leaching, so methanesulfonic acid (MSA), an alternative lixiviant was investigated for arsenic leaching and scorodite crystallization. Results of arsenic trioxide leaching show that arsenic extraction with MSA was above 90% at 80oC within 4 hours. In addition, arsenic removal in scorodite was 98% at 80oC, and scorodite was successfully crystallized at MSA medium of pH 0.5. Overall, MSA was proven to be an alternative lixiviant to treat arsenic byproduct and feasible to precipitate arsenic into scorodite in MSA medium.

 

Bioleaching of Gold: Status of Research and Where Must We Go From Here?

James McNeice, Hydrometallurgy and Environment Group, Robert M. Buchan Department of Mining, Queen’s University, Kingston, Ontario, K7L 3N6, Canada Kingston Process Metallurgy, 759 Progress Ave, Kingston, ON K7M 6N6; Fariborz Faraji, Technological Center for Industrial Residues (CTRI), Cégep de Abitibi, boulevard du Collège, Rouyn Noranda (Québec), J9X 0E1, Canada; Ahmad Ghahreman, Hydrometallurgy and Environment Group, Robert M. Buchan Department of Mining, Queen’s University, Kingston, Ontario, K7L 3N6, Canada

Gold recovery from ores and other sources is commonly undertaken by cyanidation. However, in some cases technical or legislative barriers make conventional cyanidation unfeasible. Chemical interactions with refractory ores and transportation bans can preclude implementing cyanidation to new or expanding operations. Biogenic lixiviants have been proposed as alternatives with effective recovery and low costs. Biogenic cyanide, thiosulfate, iodine, and organic acids have been applied to leach gold. This paper combines technical experience in gold bioleaching with a review of the literature to overview advantages and disadvantages of each option and what must be achieved for economic application by industry.

 

Microbial Pretreatment of Preg-Robbing Carlin-Type Carbonaceous Ore

Anthony Kaah, McEwen Mining, Nevada

Gold deposits in northern Nevada have the occurrence of carbonaceous material that tends to adsorb leached gold in a phenomenon called preg-robbing. Processing of carbonaceous ore requires the use of a Roasting facility to combust the organic carbon into CO2 and CO. For heap leach operations, having carbonaceous ore on the leach pad causes a reduction in gold recovery. Bacterial pretreatment of carbonaceous ore was successful in reducing the preg-robbing potential of carbonaceous ore samples from the Eureka trend in Nevada. The conditions for the pretreatment are as follows:

Sample particle size of 85% passing 75 microns (200 mesh)
40% solids slurry
6.5 to 7.5 pH
Temperature maintained between 37 OC to 40 OC
30 L/min air addition
24 hours residence time

For a carbonaceous ore sample, a preg-robbing reduction of 74% (94.2% to 24.6% preg-robbing) was achieved at 24 hours. Under similar conditions, another carbonaceous ore sample achieved a preg-robbing reduction of 77.3% (95.3% to 21.6% preg-robbing) at 6 hours and 78.1% preg-robbing reduction at 24 hours. This processing method could be an alternate method for pretreating carbonaceous ore for both Milling and Heap leach operations.

 

Suppression of Ammonium Thiosulfate Gold Leaching in the Presence of Arsenopyrite and a Pretreatment to Improve Gold Extraction

Takunda Joseph Mhandu, Division of Sustainable Resource Engineering, Graduate School of Engineering, Hokkaido University, Sapporo 060 0808, Japan; Sohta Hamatsu, Division of Sustainable Resource Engineering, Graduate School of Engineering, Hokkaido University, Sapporo 060 0808, Japan; Sanghee Jeon Department of Earth Resources Engineering and Environmental Science, Faculty of International Resources Science, Akita University, Akita 010 0852, Japan; Ilhwan Park Division of Sustainable Resource Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060 0808, Japan; Mayumi Ito Division of Sustainable Resource Engineering,
Faculty of Engineering, Hokkaido University, Sapporo 060 0808, Japan; Naoki Hiroyoshi Division of Sustainable Resource Engineering, Faculty of Engineering, Hokkaido University, Sapporo 060 0808, Japan

The use of thiosulfate to extract gold from refractory ores is promising because of its non-toxicity and high selectivity. Arsenopyrite is a major gold carrier mineral in refractory gold ores and known to hinder gold extraction due to high consumption of lixiviant. Hence, this study investigated the effects of arsenopyrite on gold leaching in ammonium thiosulfate solutions and found that gold extraction after leaching gold powder in the presence of arsenopyrite for 24 h was suppressed because of the unwanted decomposition of thiosulfate on the surface of arsenopyrite. To address this problem, this study investigated on the use of ammonia solution containing cupric ions pretreatment and confirmed that gold dissolution was improved in the subsequent ammonium thiosulfate leaching.

 

Copper Extraction from Chalcopyrite in Various Hydrometallurgical Systems

Jaeyeon Kim, Department of Mining Engineering, Colorado School of Mines. Kroll Institute for Extractive Metallurgy, Colorado School of Mines; Junmo Ahn, Department of Mineral Resources and Energy Engineering, Chonbuk National University; Jaeheon Lee, Department of Mining Engineering, Colorado School of Mines. Kroll Institute for Extractive Metallurgy, Colorado School of Mines

Copper sulfide concentrate leaching, particularly chalcopyrite or other primary copper sulfides, has been investigated as an alternative to the conventional smelting. The grand challenge for copper industry is to improve copper extraction from the primary sulfides such as chalcopyrite. A newly developed method using activated carbon showed almost 99% copper extraction from a chalcopyrite concentrate containing 85% chalcopyrite and 8% pyrite. The system used sulfuric acid and ferric ion as a stock solution with activated carbon as an additive. In the absence of the activated carbon, only 19.2% copper extraction was observed for 96 hours at 65℃. With 10 g/L activated carbon increased the copper extraction up to 98 % for 48 hours at 65℃ in 10 g/L H2SO4. The activation energy of the H2SO4-activated carbon leaching system was 127.47 kJ/mol from the 25-65℃ temperature range, indicating the reaction is controlled by the chemical reaction. The system enhanced the copper extraction without surface passivation under the conditions used because the solution potential has been maintained lower than 640 mV vs. SHE. This leaching system is also compatible with the current solvent extraction and electrowinning process without any modification.

 

Heap Leaching of Rare Earth Deposits – Hydrodynamic Characterization

Amado Guzman, HydroGeoSense Inc.; Toren Olson, HydroGeoSense Inc.; Randolph Scheffel, Independent Metallurgical Consulting; Tim Harrison, Ionic Rare Earths; Harley Davies, Ultramet Ltd.; Juan Illescase, USA Rare Earths Inc.

Heap leaching has been used for centuries to process low-grade ores containing significant amounts of gold and copper. As the electric age progresses and new metals and elements, such as Rare Earths, become essential, our understanding of how to process the typically low-grade deposits must improve. For successful leaching processes, an integrated evaluation of the physical (geotechnical), hydraulic, and metallurgical ore responses is necessary.
This paper will present case studies on the characterization testing of an Ionic Clay Rare Earth deposit and a Hard Rock Rare Earth deposit for heap leaching. The data shows proper agglomeration at the correct moisture content facilitates good percolation for a heap height of up to 5 to 7 meters in the Ionic Clay deposit. The Hard Rock Rare Earth deposit requires optimization of the particle size distribution to improve wetting efficiency. The data derived from the hydrodynamic characterization can be used to optimize the sample preparation and selection of operational conditions.

 

Kupferglimmer – Its Identification and Leaching in Copper Anode Slimes

Shijie Wang, Coeur Mining, Inc., Chicago, IL

Kuferglimmer is a copper-nickel-antimony oxide phase contained in some copper anode slimes. It is difficult to effectively leach copper from kupferglimmer due to its refractory nature. This paper identifies and analyzes kuferglimmer for the first time as a needle-shape mineral in slime samples. This paper presents the mineralogy results, describes how to leach kuferglimmer during slimes processing, and shows the kuferglimmer composition before and after the leach.

 

Plant Practices

Reverse Osmosis Treatment of In-situ Copper Leach Solution

Lingyu Zhang, Florence Copper, LLC

This paper summarizes the development of Reverse Osmosis treatment to concentrate low grade copper leach solution which produces high quality permeate for use as electrowinning process make up water. The demand for sustainability in the copper hydrometallurgy process is to increase sharply due to the water crisis especially in dessert area like Arizona and the significant growth of copper usage in electrical industries such as semiconductor or electrical car manufacturing. A review of RO plant optimization practices including acid RO design, fouling and scaling problems, pH control, multimedia filter management strategies, membrane selection, and clean in place frequency is given in this paper.

 

Comprehensive Analysis of Cathode Stripping Behavior: Simulation by the Finite Element Method and Experimental Results

Almeida, N.G.S, Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte MG, 31270 901, Brazil; Ciminelli, V.S.T. T., Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais (UF MG), Belo Horizonte MG, 31270 901, Brazil. Acqua Institute, Belo Horizonte MG 31270 901, Brazil; Cetlin, P.R. R., Metallurgical, Materials and Mining Engineering Graduate Program, Universidade Federal de
Minas Gerais (UFMG), Belo Horizonte MG, 31270 901, Brazil; Majuste, D., Department of Metallurgical and Materials Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte MG, 31270 901, Brazil. Acqua Institute, Belo Horizonte MG 31270 901, Brazil

The main goal of this work is to improve the fundamental understanding of the stripping behavior of electroplated metals in an attempt to better control metal sticking in industrial practice, thus minimizing its impact on cost and productivity. The effect of cathode surface roughness and number of electrowinning cycles on the adhesion of zinc deposits in aluminum blanks was evaluated by experimental investigation, while the effect of deposit thickness and adhesion strength on the stripping behavior was evaluated by finite element analysis. The experimental and simulated stripping curves (force vs. displacement plots) were analyzed by each component effect: (i) adhesion; (ii) bending; and (iii) friction. Each stage of the stripping curve was associated with the component force responsible for it. Increasing the cathode surface roughness and the number of electrowinning cycles increased the adhesion force. Deposit thickness increased the bending force. The results also showed that the bending force was the main component of the stripping curve. The adhesion strength was shown to be responsible for controlling the amount of bend, acting as a critical indirect effect on the stripping curve and deposit warping. The direct effect of adhesion, beyond controlling the bending condition, is responsible for the first peak of force in the stripping curve. The slightly ticker deposit at the bottom of the cathode due to the heterogeneous current distribution was shown to be responsible for the final force peak in the stripping curve.

 

Rare Earth/Critical Minerals

Temperature Dependence of Biooxidation of Coal-Based Pyrite

Kitsel Lusted, University of Utah; Prasenjit Podder, University of Utah; Joel Ilunga, University of Utah; Kara Sorenson, University of Utah; Prashant Sarswat, University of Michael Free, University of Utah

Rare earth elements have properties that make them useful in advanced electronics, magnets, and batteries. However, they are difficult to isolate from their constituent elements, which results in an environmentally costly operation to refine them. An environmentally friendly alternative extraction method involves biooxidation which uses bacteria to generate acid and ferric ions from pyrite to free the REEs from chemically bonded constituents. Because bacteria are living creatures, one of the most important factors to consider when running a bioreactor is the operating temperature. This study involved testing and analysis of the temperature dependence of biooxidation using pyrite concentrated from coal waste. The temperature was varied from 25°C to 40°C. Acid production in the bioreactor was monitored with pH measurements and bacterial oxidation was measured using the oxidation-reduction potential (ORP) of the system. Bacterial vitality was monitored by periodic ferrous oxidation tests which quantitatively assessed the biooxidation rate. The ferrous biooxidation rate (BOR) was evaluated using the Michaelis-Menten or Monod kinetic equations. Elemental and volumetric mass balances were done after each parameter. Pyrite recoveries were analyzed using energy-dispersive x-ray spectroscopy (EDS), scanning electron microscope (SEM) analysis, and x-ray diffraction (XRD). Additionally, bacteria species analysis showed that Leptospirillum ferriphilum was the dominant bacteria species, showing divergence from the original Acidithiobacillus ferrooxidaans culture. Analysis showed that 35°C had the lowest pH, highest ORP, and highest BOR, while 40°C caused bacterial death.

 

Hydrometallurgical Treatment of Copper Flash Smelter Dusts via Ammoniacal Leaching

Joseph Trouba, Colorado School of Mines, Kroll Institute of Extractive Metallurgy; Corby Anderson, Colorado School of Mines, Kroll Institute of Extractive Metallurgy

Cu smelter flue dusts contain appreciable quantities of Cu, which would represent a substantial financial loss if not recovered. The presence of deleterious elements including Bi, As, and Pb limits the ability to recycle dusts back into the smelter as it inhibits downstream operations. Disposal of dusts also presents a challenge, due to the toxic elements As and Cd. A hydrometallurgical method involving ammoniacal leaching for treatment of dusts addressing these challenges is presented. This method also provides improved potential for recovery of minerals critical to thin film photovoltaic applications including Cd and In.

 

Sequential Leaching of Nevada Sedimentary Claystones for Subsequent Selective Lithium Extraction

Angela Tita, Department of Mining and Metallurgical Engineering, University of Nevada, Reno; Pengbo Chu, Department of Mining and Metallurgical Engineering, University of Nevada, Reno

To meet the current high demand for lithium, new sources of lithium are needed. A Nevada sedimentary claystone containing lithium was analyzed for its composition, phase transformation, and leaching efficiency for lithium extraction through a 5-step sequential (step-by-step) leaching. Methods such as XRD, SEM, AAS, and ICP-MS were used to characterize the clay and its resulting products. The study found that the clay consisted mainly of compounds of Ca, Al, Mg, Fe, K, and Na, as well as Li having 1188 ppm. In the first step trace element extraction was performed using MgCl2, which positively impacted the second step for calcite removal. In the second step, about 50% of Ca was removed in 5 hours at room temperature with 1M sodium acetate, which was an indication that some of the Ca was associated with the carbonate-bound fraction. In the third step, the temperature was applied at 96oC with hydroxylamine hydrochloride in acetic acid. Under these conditions, less than 20% of the Fe was removed, which suggested that the Fe is barely associated with the Fe-oxide bound fraction. The last step (residual step) made use of aqua regia, aiming at attacking the silicate matrix. At this step, most of the metal ions were released. The results showed that most of the metal ions were situated in the crystalline matrix (residual fraction).

 

Intra-Lanthanide Separation Processes Using Neutral Diglycolamide Extractants

Kevin L. Lyon, Idaho National Laboratory, Idaho Falls ID, USA; Santa Jansone Popova, Oak Ridge National Laboratory, Oak Ridge TN, USA; Derek M. Brigham, Oak Ridge National Laboratory, Oak Ridge TN, USA; Mitchell R. Greenhalgh, Idaho National Laboratory, Idaho Falls ID, USA; Amy K. Welty, Idaho National Laboratory, Idaho Falls ID, USA; Melissa M. Warner, Idaho National Laboratory, Idaho Falls ID, USA; Bruce A. Moyer, Oak Ridge National Laboratory, Oak Ridge TN, USA

Separation of individual rare earth elements (REE) is often regarded as the most difficult processing step in the production of high-purity rare earth oxides for end-use technology applications due to their inherent chemical similarities. Current industrial REE separation practices utilize solvent extraction with organophosphorus extractants, a complex process plagued by poor adjacent-lanthanide selectivity, excessive chemical reagent consumption, and adverse environmental impacts. Consequently, research efforts within the Critical Materials Institute (CMI) are aimed at the development of alternative REE separation technologies that improve economic viability and environmental sustainability to enable domestic supply diversification. Recent efforts have focused on electroneutral solvating diglycolamide (DGA) extractants as an alternative method for the separation and purification of critical rare earth elements. DGAs offer distinct advantages over traditional phosphonic acid extractants used in separations including elimination of saponification to achieve high recovery in a solvent extraction cascade and improved adjacent-lanthanide separation factors, ultimately requiring fewer solvent extraction stages to facilitate the required separations. Novel DGA extractants have been synthesized and tested to maintain high intra-lanthanide selectivity, high organic-phase loading capacity, and proper phase dispersion behavior for high throughput separations. In this paper, solvent extraction cascade design principles have been tested using the well-known DGA N,N,N’,N’-tetraoctyldiglycolamide as the first test case to validate separation performance in counter-current solvent extraction equipment to obtain high degrees of REE recovery and purity. Finally, challenges and ongoing research associated with this family of neutral extractants are evaluated within the context of domestic rare earth oxide production from bastnäsite ore.

 

Enhancing the Recovery of Rare Earths and Phosphate Enriched By-product from Monazite Ore via Sulfuric Acid Baking with Additives

Tarek Mohammed, College of Science, Technology, Engineering and Mathematics, Murdoch University; Andro Tomas, College of Science, Technology, Engineering and Mathematics, Murdoch University; Gamini Senanayake, College of Science, Technology, Engineering and Mathematics, Murdoch University; Wensheng Zhang, Hydrometallurgy Innovation, CSIRO Mineral Resources

Monazite, a rare earth phosphate mineral, is the second most important primary source of REEs for increasing demand in modern technologies. Current technologies for processing monazite ore using sulfuric acid are primarily focused on REE recovery. However, these technologies result in the loss of phosphorus in waste streams, which impedes downstream REE recovery processes. Therefore, there is a need for efficient processing methods that could recover both REEs and phosphorus from monazite ore. This study presents a method for recovering both REEs and phosphorus as iron phosphate battery precursor from monazite ore by sulfuric acid baking with the addition of sulfate salts. The leaching efficiency of REEs and P varied depending on the additives used, with the highest efficiencies observed for the ferric sulfate system. As the temperature increased, the leaching efficiency of REEs and P decreased when baking with no additive. However, the addition of ferric sulfate salt to the baking reactants improved leaching efficiency of REEs and favourably enriched P in the residue for subsequent processing as battery precursor (FePO4). The XRD confirmed the successful constraining of P and Fe in the residue while more than 95% REEs were selectively leached. The results suggest that this method can be a promising alternative to conventional methods for processing monazite ore. An integrated flowsheet was proposed to produce a marketable REO product of over 99% purity.

 

Selective Recovery of Rare Earths and Phosphate By-product from Iron-rich Monazite Ore by Roastings and Water Leaching

Tarek Mohammed, College of Science, Technology, Engineering and Mathematics, Murdoch University; Gamini Senanayake, College of Science, Technology, Engineering and Mathematics, Murdoch University; Wensheng Zhang, Hydrometallurgy Innovation, CSIRO Mineral Resources

The demand for rare earth elements (REEs) has increased with the rise of modern technologies. However, current practices of processing monazite ore pose sustainability challenges. These practices involve the use of concentrated acids, which result in the discharge of acidic effluents containing dissolved gangue minerals and require energy-intensive high temperature operations. To address these challenges, a novel approach has been proposed in this study. The proposed method involves roasting the ore with NaOH, which yields water leachable Na3PO4 as a by-product that can be used in the production of fertilizer. The dephosphorized ore is then further roasted with NH4Cl, followed by water leaching, resulting in over 95% REEs recovery and merely 2% Fe. Additionally, the proposed method yields a high-purity RE2O3 product with over 99% purity, making it a promising alternative to conventional methods for processing monazite ore of high iron content. The proposed method offers numerous benefits and can contribute to the development of eco-friendly technology while promoting sustainable practices in the mining industry.

 

Fluoride-free Processing of Columbite Concentrate for Selective Recovery of Niobium and Tantalum Oxides

Himanshu Tanvar, Material Science and Worcester Polytechnic Institute; Brajendra Mishra, Material Science and Engineering, Worcester Polytechnic Institute

The industrial processes for extracting niobium and tantalum oxides depend highly on hydrofluoric acid. This work focuses on developing an alternative fluoride-free approach based on alkali treatment and solvent extraction. The application of microwaves in thermal treatment with potassium hydroxide shows positive outcomes of rapid processing with a high reaction rate and recovery. The microwave alkali treatment produces a water-soluble complex of niobium and tantalum separated in a downstream solvent extraction process using methyltrioctylammonium chloride as an extractant. Finally, niobium oxide and tantalum-rich mixed oxide with >98% purity were prepared after microwave treatment and solvent extraction.

 

Ultrasonically Generated Cyanex572 Droplets for Selective Separation of Nd, Dy, Pr, and Tb from Synthetic Leaching Solution of NdFeB Permanent Magnets: A Comparative Study

Deniz Bozkurt, The Robert M. Buchan Department of Mining, Queen’s University; Ilkay Yildiz , The Robert M. Buchan Department of Mining, Queen’s University; Farzaneh Sadri, Department of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta; Ahmad Ghahreman, The Robert M. Buchan Department of Mining, Queen’s University

Rare earth elements (REE) have characteristic features making them irreplaceable in their modern applications. With increasing awareness in the developing world, green technologies are replacing traditional energy sources, creating a huge demand on critical metals such as REE. The drawbacks associated with the use of conventional separation techniques, i.e., SX, has directed a special attention towards alternative methods. Emulsion droplets stand out by creating larger surface area, increasing the mass transfer capacity. The current investigation presents a comparison between conventional SX and ultrasonically-generated Cyanex572 droplets for selective separation of Nd, Dy, Pr, and Tb from synthetic PLS of end-of-life permanent magnets.

 

Impurity Removal and Separation of Critical Metals from Synthetic PLS of End-of-Life Permanent Magnets Using Ionic Liquids

Ilkay Yildiz, The Robert M. Buchan Department of Mining, Queen’s University; Deniz Bozkurt, The Robert M. Buchan Department of Mining, Queen’s University; Farzaneh Sadri, Department of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta; Ahmad Ghahreman, The Robert M. Buchan Department of Mining, Queen’s University

Although solvent extraction (SX) is the conventional technique to extract metals of interest from the solution, certain drawbacks such as large consumption of hazardous reagents and by-products generation has shifted the attempts to substitute them by greener reagents. Ionic Liquids offer numerous advantages over organic solvents, such as lower toxicity, non-flammability, and highly solvating features. In the current study, solution purification was performed using NaOH and Ca(OH)2 precursors on the synthetic solution of Nd, Dy, Pr, Tb, Sm, Co and Fe, followed by the application of Cyanex 272 and Ionquest 801 to separate Co, heavy and light REE from the solution.

 

Fluoride Control and Flowsheet Development for the Hydrometallurgical Processing of Bastnaesite Concentrates

Austin Rich, Colorado School of Mines; Corby Anderson Brock O’Kelley, Colorado School of Mines

Rare Earth Elements (REEs) are materials which are critical to the landscape of modern and evolving technology. In the United States, these elements often occur in bastnaesite ore, which has been historically mined and processed at the Mountain Pass mine. The most recent leaching process used on the Mountain Pass bastnaesite ore achieved a REE recovery of 55-60%. As a result of the poor recovery values, the Critical Materials Institute (CMI) commissioned an investigation on leaching recovery improvement. Colligan et al. showed that a decreased slurry density could yield leaching REE recovery values greater than 80%, and as high as 97%. However, this method still required improvement, as the leaching of such a low percentage of solids left large concentrations of hydrochloric acid in the residual leach liquor. This acid could be recycled for further leaching, which would result in much better process economics than using a new batch of acid per leach. It was ultimately found that any recycling of the solution would cause the fluoride from previous batch leaches to react with fresh bastnaesite, which would form insoluble Rare Earth Fluoride and decrease process REE recovery. Therefore, this study was conducted to develop a process which could remove the fluoride from the process solution, thus mitigating its detrimental effects. To achieve this goal, analytical procedures were developed to quantify fluoride in both solid and liquid REE-bearing matrices. As a byproduct of the testing of a fluoride removal process, a continuous bastnaesite leaching process flowsheet was developed throughout the test work. The test work evaluated data for processes including bastnaesite leaching, solvent extractant, stripping, precipitation, fluoride removal, and activated alumina regeneration. Overall, it was determined that a continuous, single-stage hydrometallurgical process was metallurgically viable, as it achieved a leaching REE recovery of 91% and an effective recovery (all processes combined through product precipitation) of 80%. Additionally, it was proven that fluoride could be successfully removed from the solution, so that the solution could be recirculated for subsequent leaching cycles.

 

The Use of Hydrogen Peroxide to Inhibit Silicon Co-Extraction with Iron during Slag Leaching

Michael Caplan, Kroll Institute for Extractive Metallurgy, Colorado School of Mines; Corby Anderson, Kroll Institute for Extractive Metallurgy, Colorado School of Mines; Erik Spiller, Kroll Institute for Extractive Metallurgy, Colorado School of Mines; Roberto Huamani, Universidad Nacional de San Agustin de Arequipa

The extraction of silicon and iron commonly pose problems during hydrometallurgical leaching. These problems generally arise during downstream processing where iron can co-extract with target elements and silicon-based gels can hinder processing. This work presents a mechanism by which hydrogen peroxide can be used to suppress iron and silicon extraction during leaching of pyrometallurgical slags with sulfuric acid. Ferro-silicates are common in slags, therefore the extraction of iron and silicon by leaching in slags is linked. By increasing the oxidizing environment during leaching, the thermodynamically favored iron bearing species becomes solid. This reduces the degradation of the ferro-silicates in slag, which reduced the silicon available for extraction. This work supports this mechanism by leaching a mixture of copper reverberatory slag and lead blast furnace slag with sulfuric acid and hydrogen peroxide. The presence of hydrogen peroxide suppressed the extraction of both iron and silicon.

 

Direct Leaching Methods for Lithium Extraction from Lepidolite Minerals

Angeline Kudzai Mchibwa, Murdoch University; Gamini Senanayake, Murdoch University; Manickam Minakshi Sundaram, Murdoch University

The current metallurgical processing technologies for lithium extraction from spodumene and lepidolite are based on the Sulphuric Acid Process (SAP) developed in the early 1950s. These technologies are energy intensive and involve steps such as decrepitation (1100°C), sulphuric acid digestion (250°C) and roasting (750-1000 °C) which generate voluminous waste. In this project, we investigated the extraction of lithium from lepidolite using alternative techniques such as direct acid leaching at mild temperatures to obtain Li extraction efficiencies above 95%. The findings provide useful insights for alternative routes for lithium extraction which are cleaner and more cost-effective, subjected to favourable economic outcomes.

 

Separation of Rare Earth Elements Using Electrodialysis

Gisele Azimi, Laboratory for Strategic Materials, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada. Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario M5S 3E4, Canada; Lingyang Ding, Laboratory for Strategic Materials, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Canada

Rare earth elements (REEs) are widely utilized in advanced green technologies including permanent magnets for wind turbines and electric vehicles. The REE processing involves leaching followed by separation and purification. Conventional methods for REE separation are precipitation, ion exchange, and solvent extraction. Recently, the electrodialysis method has gained increasing interest as an effective separation method. Electrodialysis offers several advantages including simple, continuous, and multi-stages operation. Chelating agents are used to provide additional selectivity in this method. Here, the electrodialysis method with Hydroxyethylethylenediaminetriacetic acid chelating agent is applied to separate cerium-lanthanum from praseodymium-neodymium as two groups. A separation model is developed to simulate the separation characteristics of REEs. Using the model, the optimum ratio of HEDTA to neodymium that results in highest product purity and yield is determined.

 

Recovery/Recycling

Palladium Pressure Leaching Kinetics in Chloride medium, from Printed Circuit Boards, in a Pressure Reactor

Guadalupe Martínez Ballesteros, Chemical Engineering and Metallurgy Department, University of Sonora, Rosales y Blvd. Luis Encinas s/n, Hermosillo, Sonora 83000, México; Jesús Leobardo Valenzuela García, Chemical Engineering and Metallurgy Department, University of Sonora, Rosales y Blvd. Luis Encinas s/n, Hermosillo, Sonora 83000, México; Patricia Guerrero Germán, Chemical Engineering and Metallurgy Department, University of Sonora, Rosales y Blvd. Luis Encinas s/n, Hermosillo, Sonora 83000, México; María Mercedes Salazar Campoy, Chemical Engineering and Metallurgy Department, University of Sonora, Rosales y Blvd. Luis Encinas s/n, Hermosillo, Sonora 83000, México; Agustín Gómez Alvarez, Chemical Engineering and Metallurgy Department, University of Sonora, Rosales y Blvd. Luis Encinas s/n, Hermosillo, Sonora 83000, México

The recovery of palladium (Pd) by recycling printed circuit boards (PCBs) has attracted attention in recent years because this metal is found in low concentrations in the earth’s crust and the demand for it increases day by day due to its chemical and physical properties. Currently, the extraction of Pd from waste PCBs through an efficient and ecological process remains a challenge. In the present study, palladium leaching was carried out in a PARR titanium reactor with a capacity of 1 L with an acid leaching agent under pressure from printed circuit boards, using [NaCl]=0.017 M, [NaClO]= 0.067 M and varying the concentration of hydrochloric acid, pressure, and temperature, obtaining the best extraction results when using a pressure = 0.34 MPa, temperature = 70 °C and [HCl] = 4 M, with a recovery greater than 93% Pd, this it was based on the thermodynamic analysis of the Pd-Cl-H2O system. In addition, the study of the extraction kinetics was carried out to know the leaching reaction mechanism, which was carried out at 0.34 MPa, 20% solids, 600 rpm, varying the temperature (40, 50, 60, and 70 °C) and different reaction times (from 10 to 120 min). Obtaining an activation energy (Ea) less than 1 kJ/mol, the mechanism is diffusion through the product layer and an extraction greater than 93% of Pd at 70 °C and 120 min.

 

Method for Manufacturing High-purity Zinc Oxide Using RHF Dust

Hyoseok Song, S IMPAC Holdings RISTecBiz Plant 1 Co., Ltd; Daewoo Kim, SIMPAC Holdings RISTecBiz Plant 1 Co., Ltd; Kwanbin Kim, SIMPAC Holdings RISTecBiz Plant 1 Co., Ltd; Hyeonjon Yun, SIMPAC Holdings RISTecBiz Plant 1 Co., Ltd

This process is a method of manufacturing high-purity zinc oxide by recycling by-products generated in steel mills. The by-product is zinc dust generated in the RHF (Rotary Hearth Furnace) process. During the process, Fe, Mn, Pb, Cd, Cu and Ni are removed by dissolving zinc dust with aqueous hydrochloric acid solution containing 30-60% of zinc. Thereafter, zinc hydroxide obtained by precipitation reaction with sodium hydroxide is washed twice and dried to produce high-purity zinc oxide.

 

Recycling of Bauxite Residue (red mud) for Recovery of Metallic Values

Himanshu Tanvar, Material Science and Engineering, Worcester Polytechnic Institute; Brajendra Mishra, Material Science and Engineering, Worcester Polytechnic Institute

Bauxite residue is an industrial by-product generated during alumina production through the Bayer process. The worldwide stockpiles of bauxite residue are expected to reach 10 billion tons by 2050 if not processed effectively. Limited industrial-scale processing (3-4 %) of bauxite residue is mainly due to complex physical and chemical characteristics. High alkalinity and multiple elements make the recycling process complicated and expensive. The following work presents a hydrometallurgical approach for effectively recycling bauxite residue to recover high-purity metal oxide products, including magnetite, alumina, titanium dioxide, and scandium oxide. A pyrometallurgical method based on smelting for recovery of pig iron and subsequent processing of slag for value recovery is also discussed. A comparative analysis of hydro and pyrometallurgical processes is carried out to highlight the key differences and potential for large-scale application.

 

Potential of Total Recycling Valuable Materials from Light-Emitting Diodes Module by Pre-Treatment Using Heating and Resin Decomposition

Seunghyun Kim, Department of Integrated Energy and Infra System, Kangwon National University, Chuncheon si, Kangwon do, 24341, Republic of Korea; Ha Bich Trinh, Department of Integrated Energy and Infra System, Kangwon National University, Chuncheon si, Kangwon do, 24341, Republic of Korea; Taehun Son, Department of Integrated Energy and Infra System, Kangwon National University, Chuncheon si, Kangwon do, 24341, Republic of Korea; Jaeryeong Lee, Department of Integrated Energy and Infra System, Kangwon National University, Chuncheon si, Kangwon do, 24341, Republic of Korea

The recycling of LED lamps is important to reclaim the valuable materials and prevent the pollution problem. Herein, a process was investigated to recycle all the constituents from the LED modules. Firstly, the LED package and the printed circuit board of LED module were completely separated at 250 oC for 15 min. The further decomposition of resin was studied in suitable solvents: (i) epoxy resin coated on PCB in polyethylene glycol and sodium hydroxide, and (ii) silicon resin from LED package in N-methyl-2-pyrrolidone and N.N-Dimethylformamide. The remained encapsulant was subsequently processed to recovery gallium and other valuable metals.

 

Recovery of Valuable Metals from LIBs Black Mass by Nickel Pre-loaded Extractants

Yeon Chul Cho, Daejin University; Ki Hun Kim, Daejin University; Junmo Ahn, Jeonbuk National University; Jaewoo Ahn, Daejin University

Recycling of valuable metals from waste Li-ion batteries(LIBs) has recently attracted significant attention. A leaching solution obtained by leaching LIBs black mass with sulfuric acid contains copper, aluminum, manganese, cobalt and nickel. In order to remove Cu, Al and Mn from the leaching solution and recover Co and Ni, experimental work was performed using solvent extraction with Ni-D2EHPA and Ni-PC88A as extractants. The effects of various process parameters on pre-loading and extraction were investigated. Based on experimental designs, the parameters with the largest effects on the process performance were determined to be organic phase saponification, nickel concentration and phase ratio for pre-loading.

 

Leaching of Lithium and Cobalt from Cathode of Lithium-ion Batteries with Novel Deep Eutectic Solvents

Shoaib Afzal, University of Engineering and Technology Lahore, Pakistan; Faisal Sajjad, University of Engineering and Technology, Lahore, Pakistan; Qasim Raza, University of Engineering and Technology, Lahore, Pakistan; Haseeb Gillani, University of Engineering and Technology, Lahore, Pakistan; Dr. Zulfiqar Ali, University of Engineering and Technology, Lahore, Pakistan

Modern technology in the transport industry especially about the electric vehicles results in the rapid production of the waste in the form of the batteries. Lithium percentage starts depleting due to its huge demand. Waste disposal challenge of end-of-life Lithium-ion batteries was also a great challenge. A lithium-ion battery is a favorable energy storage technology with no successful recycling model. In the future it can cause some serious damage to the environment. To counter this problem some recycling techniques should be addressed (1)(15). Use of the Hydrometallurgical technique has somehow bad impression towards economy, green environment, corrosiveness and consumption of the energy. That’s why the leaching technique that is known to be most optimum and safer for environment is the use of Deep Eutectic Solvent (DES) (2)(11)(12). In this case, we want to convert from the use of mineral acids and organic acids that are main features of the hydrometallurgical technique and are also very corrosive and have additional reducing agents to the more safe and optimum technique that is use of DES(3)(17). For this objective a battery was firstly pretreated (manual casing out). Then we got the layers from inside the battery which were thin. Cathode layer is separated out. After getting information about the cathode layer, we just simply put it into the DES solution. It reacts with the solution. Once it reacts the metal concentration in the layer just dissolved in the liquid. It was then heated at the Temperature of 600C to make more solubility. At the end, it was passed through the process of filtration and the residue we had was our metals lithium and cobalt. Filtrate was sent for XRD to determine the structure of crystal. It is expected to get a green reagent for Li-ion battery through this study. Further investigations could be done on recycling anode material from theses batteries.

 

Infrared Assisted Dissolution as a New Solubilization Method for Critical Metals in Different E-Waste Streams

Mélodie Bonin, Chemistry department, Université Laval; Frédéric Georges Fontaine, Chemistry department, Université Laval; Dominic Larivière, Chemistry department, Université Laval

Focused infrared digestion (FIRD) was evaluated as a new heating strategy for the solubilization of rare earth elements, which are considered as critical elements in many countries, in electronic waste (e-waste). Two different e-waste streams were investigated: neodymium magnets (Nd magnets) and fluorescent lamp phosphors (FLPs). Parameters relevant to digestion method, such as the nature and concentration of acids used and the solid/liquid ratio are discussed. The FIRD method is compared to more conventional digestion approaches such as hot plate, microwave, and alkaline fusion. For the magnets, FIRD is faster than hot plate and more convenient than microwave and alkaline dissolution. Investigation regarding the pros and cons of FIRD for the recycling of FLPs is still ongoing.

 

Solvometallurgical Recycling of Lithium-ion Battery Components

Halimeh Askari Sabzkoohi, Department of Mining, Metallurgical, and Materials Engineering, Université Laval, Québec, Québec, G1V 0A6, Canada; Georgios Kolliopoulos, Department of Mining, Metallurgical, and Materials Engineering, Université Laval, Québec, Québec, G1V 0A6, Canada

E-waste generation, including spent lithium-ion batteries (LIBs), is a significant problem facing the world that can be turned into a critical and strategic metal recycling opportunity. Although hydrometallurgy offers a sustainable pathway to extract and recover these metals, the extensive use of aqueous solutions generates toxic effluents and raises concerns over the social acceptability of such projects. In this study, we report on a new solvometallurgical process paradigm to recover metals from lithium-ion battery components using green selective anhydrous solvents, namely deep eutectic solvents. Our approach promises to minimize water use and effluent generation in process circuits, thus improving the overall efficiency of metal recycling processes.

 

A Sustainable Method to Recover the Critical Metals from Spent Lithium-Ion Batteries by Glycine and Sodium Metabisulfite in a Near-Neutral Solution

Jiajia Wu, Department of Mining and Geological Engineering, University of Arizona, Tucson, AZ 85721, USA; Jaeheon Lee, Department of Mining Engineering, Colorado School of Mines, Golden, CO 80401, USA

A green leaching system consisting of glycine and sodium metabisulfite was proposed to recover critical metals from spent lithium-ion batteries (LIBs). The preliminary leaching study using synthetic LiCoO2 revealed that metal extraction was 99.9% for cobalt and 99.8% for lithium under optimal conditions. Following metal dissolution, cobalt was separated using an acidification-precipitation technique involving oxalic acid as the precipitant, and glycine was recycled into the leaching step. This leaching system operates at near-neutral conditions and is cost-effective compared with the conventional method, making it an economical alternative for recycling spent LIBs.

 

Separation Technologies

On The Feasibility of Forward Osmosis and Freeze Concentration: A Process Simulation and Cost Analysis

Runlin Yuan, Chemical Engineering & Applied Chemistry, Institute for Water Innovation, University of Toronto; Vladimiros G. Papangelakis, Chemical Engineering & Applied Chemistry, Institute for Water Innovation, University of Toronto

Forward osmosis and freeze concentration (FO-FC) is a hybrid membrane-thermal process for water recovery. To fully understand its energy savings compared to conventional evaporative technologies, a thermodynamic process model was built using the OLI Flowsheet software. By simulating the operating conditions of a realistic FO-FC process and incorporating some basic heat integration, the energy cost was calculated to be 19 kWh/m3. It was also shown that the FC unit must be able to produce high purity ice otherwise the chemical cost of replenishing the lost draw solute can be prohibitive to the FO-FC process.

 

Rare Earth Elements Separation Principles and Methods

Michael L. Free, University of Utah; Prashant K. Sarswat, University of Utah

Rare earth elements are critical to many modern devices. REEs are not as rare in ores as many common elements, but many of them are rare in applications because of their cost and availability. Much of their low market availability and relatively high cost are related to their similarities in properties, which make them difficult to separate. This paper provides a brief overview of various fundamental principles, such as reaction free energies, equilibrium constants, and electrochemical potentials as well as application methods that can be used to separate rare earth elements. The principles that establish what is possible in terms of extraction, separation, and recovery of rare earth elements and critical elements are based on the atomic level properties of the elements as well as the processing methods with related time, temperature, and mass transport parameter effects. Correspondingly, the main tools for separating elements are generally related to selective complexation, precipitation, oxidation/reduction, and mass transport.

 

Copper Refinery and Impurity Control

Bradford C. Wesstrom, Freeport-McMoRan Copper & Gold, El Paso Refinery, 897 Hawkins, El Paso, Texas

Copper refining requires the removal of impurities that can build up in the electrolyte. This is typically done by removing a small amount of electrolyte from the refinery. This paper will cover the control methods used at the Freeport-McMoRan Refinery in El Paso, Texas for these soluble electrolyte impurities.