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Publisher: Elsevier   (Total: 3162 journals)

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Showing 1201 - 1400 of 3162 Journals sorted alphabetically
Growth Factors and Cytokines in Health and Disease     Full-text available via subscription   (Followers: 1)
Growth Hormone & IGF Research     Hybrid Journal   (Followers: 16, SJR: 1.059, CiteScore: 2)
Gynecologic Oncology     Hybrid Journal   (Followers: 25, SJR: 2.339, CiteScore: 4)
Gynecologic Oncology Reports     Open Access   (Followers: 10, SJR: 0.307, CiteScore: 1)
Gynécologie Obstétrique & Fertilité     Full-text available via subscription   (Followers: 1)
Habitat Intl.     Hybrid Journal   (Followers: 6, SJR: 1.336, CiteScore: 3)
Hand Clinics     Full-text available via subscription   (Followers: 5, SJR: 0.556, CiteScore: 1)
Hand Surgery and Rehabilitation     Full-text available via subscription   (Followers: 4, SJR: 0.358, CiteScore: 1)
Handai Nanophotonics     Full-text available via subscription  
Handbook of Adhesives and Sealants     Full-text available via subscription   (Followers: 2)
Handbook of Agricultural Economics     Full-text available via subscription   (Followers: 3)
Handbook of Algebra     Full-text available via subscription  
Handbook of Analytical Separations     Full-text available via subscription   (Followers: 3)
Handbook of Behavioral Neuroscience     Full-text available via subscription   (Followers: 3)
Handbook of Biological Physics     Full-text available via subscription  
Handbook of Chemical Neuroanatomy     Full-text available via subscription  
Handbook of Clinical Neurology     Full-text available via subscription   (Followers: 2, SJR: 1.007, CiteScore: 2)
Handbook of Clinical Neurophysiology     Full-text available via subscription  
Handbook of Complex Analysis     Full-text available via subscription  
Handbook of Computational Economics     Full-text available via subscription   (Followers: 1, SJR: 4.16, CiteScore: 2)
Handbook of Defense Economics     Full-text available via subscription   (Followers: 1)
Handbook of Development Economics     Full-text available via subscription   (Followers: 7)
Handbook of Differential Equations: Evolutionary Equations     Full-text available via subscription  
Handbook of Differential Equations: Ordinary Differential Equations     Full-text available via subscription  
Handbook of Differential Equations: Stationary Partial Differential Equations     Full-text available via subscription   (Followers: 2)
Handbook of Differential Geometry     Full-text available via subscription  
Handbook of Dynamical Systems     Full-text available via subscription   (Followers: 1)
Handbook of Econometrics     Full-text available via subscription   (Followers: 8)
Handbook of Economic Forecasting     Full-text available via subscription   (Followers: 1)
Handbook of Economic Growth     Full-text available via subscription   (Followers: 2)
Handbook of Environmental Economics     Full-text available via subscription   (Followers: 2)
Handbook of Experimental Economics Results     Full-text available via subscription   (Followers: 4)
Handbook of Exploration and Environmental Geochemistry     Full-text available via subscription   (Followers: 2)
Handbook of Exploration Geochemistry     Full-text available via subscription   (Followers: 1)
Handbook of Ferromagnetic Materials     Full-text available via subscription   (Followers: 1)
Handbook of Game Theory with Economic Applications     Full-text available via subscription   (Followers: 1)
Handbook of Geophysical Exploration: Seismic Exploration     Full-text available via subscription  
Handbook of Health Economics     Full-text available via subscription   (Followers: 10)
Handbook of Immunohistochemistry and in Situ Hybridization of Human Carcinomas     Full-text available via subscription   (Followers: 1)
Handbook of Income Distribution     Full-text available via subscription   (Followers: 2)
Handbook of Industrial Organization     Full-text available via subscription   (Followers: 3)
Handbook of Intl. Economics     Full-text available via subscription  
Handbook of Labor Economics     Full-text available via subscription   (Followers: 14)
Handbook of Law and Economics     Full-text available via subscription   (Followers: 17)
Handbook of Macroeconomics     Full-text available via subscription   (Followers: 6, SJR: 0, CiteScore: 2)
Handbook of Magnetic Materials     Full-text available via subscription   (Followers: 2, SJR: 0.467, CiteScore: 2)
Handbook of Mathematical Economics     Full-text available via subscription  
Handbook of Mathematical Fluid Dynamics     Full-text available via subscription   (Followers: 2)
Handbook of Metal Physics     Full-text available via subscription  
Handbook of Monetary Economics     Full-text available via subscription   (Followers: 5)
Handbook of Natural Resource and Energy Economics     Full-text available via subscription   (Followers: 3)
Handbook of Numerical Analysis     Full-text available via subscription   (Followers: 4)
Handbook of Perception and Action     Full-text available via subscription   (Followers: 2)
Handbook of Petroleum Exploration and Production     Full-text available via subscription   (Followers: 2)
Handbook of Population and Family Economics     Full-text available via subscription   (Followers: 3)
Handbook of Powder Technology     Full-text available via subscription   (Followers: 6)
Handbook of Public Economics     Full-text available via subscription  
Handbook of Regional and Urban Economics     Full-text available via subscription   (Followers: 1)
Handbook of Sensors and Actuators     Full-text available via subscription   (Followers: 10)
Handbook of Social Choice and Welfare     Full-text available via subscription   (Followers: 3)
Handbook of Statistics     Full-text available via subscription   (Followers: 7, SJR: 0.102, CiteScore: 0)
Handbook of Surface Science     Full-text available via subscription   (Followers: 4, SJR: 0.193, CiteScore: 0)
Handbook of Systemic Autoimmune Diseases     Full-text available via subscription   (Followers: 2)
Handbook of the Economics of Art and Culture     Full-text available via subscription   (Followers: 1)
Handbook of the Economics of Education     Full-text available via subscription   (Followers: 9, SJR: 0, CiteScore: 2)
Handbook of the Economics of Finance     Full-text available via subscription   (Followers: 6)
Handbook of the Economics of Giving, Altruism and Reciprocity     Full-text available via subscription  
Handbook of the Geometry of Banach Spaces     Full-text available via subscription   (Followers: 1)
Handbook of the History of Logic     Full-text available via subscription   (Followers: 1)
Handbook of Thermal Analysis and Calorimetry     Full-text available via subscription   (Followers: 1)
Handbook of Thermal Conductivity     Full-text available via subscription   (Followers: 4)
Handbook of Vapor Pressure     Full-text available via subscription  
Handbook on the Physics and Chemistry of Rare Earths     Full-text available via subscription   (Followers: 3, SJR: 0.755, CiteScore: 3)
Handbooks of Management Accounting Research     Full-text available via subscription   (Followers: 4)
HardwareX     Open Access  
Harmful Algae     Hybrid Journal   (Followers: 5, SJR: 1.531, CiteScore: 4)
HBRC J.     Open Access   (Followers: 2)
Health & Place     Hybrid Journal   (Followers: 15, SJR: 1.506, CiteScore: 3)
Health Outcomes Research in Medicine     Hybrid Journal   (Followers: 3)
Health Policy     Hybrid Journal   (Followers: 42, SJR: 1.252, CiteScore: 2)
Health Policy and Technology     Hybrid Journal   (Followers: 4, SJR: 0.322, CiteScore: 1)
Health Professions Education     Open Access   (Followers: 3)
Healthcare : The J. of Delivery Science and Innovation     Full-text available via subscription   (Followers: 1)
Hearing Research     Hybrid Journal   (Followers: 11, SJR: 1.35, CiteScore: 3)
Heart & Lung: The J. of Acute and Critical Care     Hybrid Journal   (Followers: 10, SJR: 0.757, CiteScore: 2)
Heart Failure Clinics     Full-text available via subscription   (Followers: 2, SJR: 1.153, CiteScore: 2)
Heart Rhythm     Hybrid Journal   (Followers: 10, SJR: 3.231, CiteScore: 4)
Heart, Lung and Circulation     Full-text available via subscription   (Followers: 9, SJR: 0.599, CiteScore: 1)
HeartRhythm Case Reports     Open Access   (SJR: 0.232, CiteScore: 0)
Heliyon     Open Access   (SJR: 0.355, CiteScore: 1)
Hellenic J. of Cardiology     Open Access   (Followers: 1, SJR: 0.479, CiteScore: 1)
Hematology, Transfusion and Cell Therapy     Open Access   (Followers: 1)
Hematology/Oncology and Stem Cell Therapy     Open Access   (Followers: 4, SJR: 0.532, CiteScore: 1)
Hematology/Oncology Clinics of North America     Full-text available via subscription   (Followers: 6, SJR: 1.282, CiteScore: 3)
Hepatobiliary & Pancreatic Diseases Intl.     Full-text available via subscription   (Followers: 1, SJR: 0.711, CiteScore: 2)
High Energy Density Physics     Hybrid Journal   (Followers: 2, SJR: 0.933, CiteScore: 2)
Hipertensión y Riesgo Vascular     Full-text available via subscription   (SJR: 0.115, CiteScore: 0)
Historia Mathematica     Full-text available via subscription   (Followers: 1, SJR: 0.174, CiteScore: 0)
History of CERN     Full-text available via subscription   (Followers: 1)
History of Neuroscience in Autobiography     Full-text available via subscription   (Followers: 3)
HIV & AIDS Review     Full-text available via subscription   (Followers: 12, SJR: 0.134, CiteScore: 0)
Homeopathy     Hybrid Journal   (Followers: 6, SJR: 0.678, CiteScore: 1)
HOMO - J. of Comparative Human Biology     Hybrid Journal   (Followers: 2, SJR: 0.335, CiteScore: 1)
Hong Kong J. of Nephrology     Open Access   (Followers: 2, SJR: 0.137, CiteScore: 0)
Hong Kong J. of Occupational Therapy     Open Access   (Followers: 42, SJR: 0.237, CiteScore: 1)
Hong Kong Physiotherapy J.     Open Access   (Followers: 12, SJR: 0.183, CiteScore: 0)
Hormigón y Acero     Full-text available via subscription  
Hormones and Behavior     Hybrid Journal   (Followers: 12, SJR: 1.638, CiteScore: 4)
Horticultural Plant J.     Open Access   (Followers: 5)
Hospital Medicine Clinics     Full-text available via subscription   (Followers: 2, SJR: 0.107, CiteScore: 0)
Human Factors in Information Technology     Full-text available via subscription   (Followers: 35)
Human Immunology     Hybrid Journal   (Followers: 17, SJR: 0.856, CiteScore: 2)
Human Movement Science     Hybrid Journal   (Followers: 15, SJR: 0.756, CiteScore: 2)
Human Pathology     Hybrid Journal   (Followers: 26, SJR: 1.304, CiteScore: 3)
Human Pathology : Case Reports     Open Access   (Followers: 1, SJR: 0.136, CiteScore: 0)
Human Resource Management Review     Hybrid Journal   (Followers: 50, SJR: 1.675, CiteScore: 4)
Hydrometallurgy     Hybrid Journal   (Followers: 13, SJR: 1.208, CiteScore: 3)
IATSS Research     Open Access   (SJR: 0.37, CiteScore: 1)
Icarus     Hybrid Journal   (Followers: 73, SJR: 2.037, CiteScore: 3)
ICT Express     Open Access   (SJR: 0.234, CiteScore: 1)
IDCases     Open Access   (SJR: 0.344, CiteScore: 1)
IERI Procedia     Open Access   (Followers: 1)
IFAC-PapersOnLine     Open Access   (SJR: 0.26, CiteScore: 1)
IIMB Management Review     Open Access   (Followers: 9, SJR: 0.24, CiteScore: 1)
IJC Heart & Vessels     Open Access   (Followers: 1)
IJC Heart & Vasculature     Open Access   (Followers: 1, SJR: 0.342, CiteScore: 1)
IJC Metabolic & Endocrine     Open Access   (Followers: 1, SJR: 0.4, CiteScore: 1)
Image and Vision Computing     Hybrid Journal   (Followers: 15, SJR: 0.612, CiteScore: 3)
Imagen Diagnóstica     Full-text available via subscription   (SJR: 0.106, CiteScore: 0)
Imagerie de la Femme     Full-text available via subscription   (Followers: 1, SJR: 0.124, CiteScore: 0)
Immunity     Full-text available via subscription   (Followers: 53, SJR: 13.393, CiteScore: 16)
Immuno-analyse & Biologie Spécialisée     Full-text available via subscription   (Followers: 2)
Immunobiology     Hybrid Journal   (Followers: 9, SJR: 1.1, CiteScore: 3)
Immunology and Allergy Clinics of North America     Full-text available via subscription   (Followers: 6, SJR: 1.132, CiteScore: 3)
Immunology Letters     Hybrid Journal   (Followers: 12, SJR: 1.168, CiteScore: 3)
Immunotoxicology of Drugs and Chemicals: an Experimental and Clinical Approach     Full-text available via subscription   (Followers: 1)
Implantodontie     Full-text available via subscription  
Indagationes Mathematicae     Open Access   (Followers: 1, SJR: 0.685, CiteScore: 1)
Indian Heart J.     Open Access   (Followers: 4, SJR: 0.333, CiteScore: 1)
Indian J. of Medical Specialities     Hybrid Journal   (SJR: 0.118, CiteScore: 0)
Indian J. of Tuberculosis     Full-text available via subscription   (SJR: 0.221, CiteScore: 0)
Indian Pacing and Electrophysiology J.     Open Access   (SJR: 0.273, CiteScore: 0)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 3)
Industrial Crops and Products     Hybrid Journal   (Followers: 5, SJR: 1.091, CiteScore: 4)
Industrial Marketing Management     Hybrid Journal   (Followers: 23, SJR: 1.663, CiteScore: 4)
Industrial Safety Series     Full-text available via subscription   (Followers: 16)
Infant Behavior and Development     Hybrid Journal   (Followers: 14, SJR: 0.784, CiteScore: 2)
Infectio     Open Access   (SJR: 0.133, CiteScore: 0)
Infection, Disease & Health     Open Access   (Followers: 8, SJR: 0.23, CiteScore: 1)
Infection, Genetics and Evolution     Hybrid Journal   (Followers: 5, SJR: 1.278, CiteScore: 3)
Infectious Disease Clinics of North America     Full-text available via subscription   (Followers: 5, SJR: 2.359, CiteScore: 5)
Informatics in Medicine Unlocked     Open Access   (SJR: 0.224, CiteScore: 1)
Information & Management     Hybrid Journal   (Followers: 56, SJR: 1.628, CiteScore: 5)
Information and Computation     Hybrid Journal   (Followers: 4, SJR: 0.504, CiteScore: 1)
Information and Organization     Hybrid Journal   (Followers: 39, SJR: 1.202, CiteScore: 3)
Information and Software Technology     Hybrid Journal   (Followers: 6, SJR: 0.581, CiteScore: 4)
Information Economics and Policy     Hybrid Journal   (Followers: 4, SJR: 0.63, CiteScore: 1)
Information Fusion     Hybrid Journal   (Followers: 2, SJR: 1.832, CiteScore: 7)
Information Processing & Management     Hybrid Journal   (Followers: 282, SJR: 0.92, CiteScore: 4)
Information Processing in Agriculture     Open Access   (SJR: 0.352, CiteScore: 2)
Information Processing Letters     Hybrid Journal   (Followers: 6, SJR: 0.412, CiteScore: 1)
Information Sciences     Hybrid Journal   (Followers: 335, SJR: 1.635, CiteScore: 5)
Information Security Technical Report     Full-text available via subscription   (Followers: 12)
Information Systems     Hybrid Journal   (Followers: 13, SJR: 0.805, CiteScore: 4)
Infosecurity     Full-text available via subscription   (Followers: 11)
Infrared Physics & Technology     Hybrid Journal   (Followers: 12, SJR: 0.54, CiteScore: 2)
Injury     Hybrid Journal   (Followers: 18, SJR: 0.99, CiteScore: 2)
Injury Extra     Open Access   (Followers: 2)
Inmunología     Full-text available via subscription   (Followers: 2)
Innovative Food Science & Emerging Technologies     Hybrid Journal   (Followers: 5, SJR: 1.201, CiteScore: 3)
Inorganic Chemistry Communications     Hybrid Journal   (Followers: 13, SJR: 0.43, CiteScore: 2)
Inorganica Chimica Acta     Hybrid Journal   (Followers: 9, SJR: 0.485, CiteScore: 2)
Insect Biochemistry and Molecular Biology     Hybrid Journal   (Followers: 3, SJR: 1.912, CiteScore: 4)
Instabilities in Silicon Devices     Full-text available via subscription   (Followers: 1)
Insulin     Full-text available via subscription   (Followers: 5)
Insurance: Mathematics and Economics     Hybrid Journal   (Followers: 9, SJR: 1.083, CiteScore: 2)
Integration, the VLSI J.     Hybrid Journal   (Followers: 6, SJR: 0.223, CiteScore: 1)
Integrative Medicine Research     Open Access   (Followers: 3)
Intellectual Economics     Open Access  
Intelligence     Hybrid Journal   (Followers: 7, SJR: 1.633, CiteScore: 3)
Intensive and Critical Care Nursing     Hybrid Journal   (Followers: 28, SJR: 0.611, CiteScore: 2)
Interdisciplinary Neurosurgery     Open Access   (SJR: 0.164, CiteScore: 0)
Interface Science and Technology     Full-text available via subscription  
Intermetallics     Hybrid Journal   (Followers: 22, SJR: 1.568, CiteScore: 4)
Internet Interventions : The application of information technology in mental and behavioural health     Open Access   (Followers: 4, SJR: 1.962, CiteScore: 4)
Interventional Cardiology Clinics     Full-text available via subscription   (Followers: 3, SJR: 0.156, CiteScore: 0)
Intl. Biodeterioration & Biodegradation     Hybrid Journal   (Followers: 1, SJR: 1.086, CiteScore: 4)
Intl. Business Review     Hybrid Journal   (Followers: 10, SJR: 1.012, CiteScore: 3)
Intl. Communications in Heat and Mass Transfer     Hybrid Journal   (Followers: 21, SJR: 1.553, CiteScore: 5)
Intl. Comparative Jurisprudence     Open Access   (Followers: 2)
Intl. Dairy J.     Hybrid Journal   (Followers: 6, SJR: 1.051, CiteScore: 2)
Intl. Economics     Hybrid Journal   (Followers: 4, SJR: 0.451, CiteScore: 1)
Intl. Emergency Nursing     Hybrid Journal   (Followers: 10, SJR: 0.461, CiteScore: 1)
Intl. Geophysics     Full-text available via subscription   (Followers: 3)
Intl. Immunopharmacology     Hybrid Journal   (Followers: 2, SJR: 1.051, CiteScore: 3)
Intl. J. for Parasitology     Hybrid Journal   (Followers: 11, SJR: 1.638, CiteScore: 4)
Intl. J. for Parasitology : Drugs and Drug Resistance     Open Access   (Followers: 4, SJR: 1.556, CiteScore: 4)
Intl. J. for Parasitology : Parasites and Wildlife     Open Access   (Followers: 2, SJR: 1.455, CiteScore: 3)
Intl. J. of Accounting     Hybrid Journal   (Followers: 1)
Intl. J. of Accounting Information Systems     Hybrid Journal   (Followers: 5, SJR: 0.399, CiteScore: 2)

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Journal Cover
Journal Prestige (SJR): 1.208
Citation Impact (citeScore): 3
Number of Followers: 13  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0304-386X
Published by Elsevier Homepage  [3162 journals]
  • Interactions of mimic weathered pyrite surfaces (FeS2) with acidic culture
           media (0 K): An approach for (bio)leaching applications
    • Abstract: Publication date: Available online 7 November 2018Source: HydrometallurgyAuthor(s): Albert Saavedra, J. Viridiana García-Meza, Eduardo Cortón, Ignacio González In biohydrometallurgical processes, a mineral exhibits different oxidation phases due to the system's heterogeneity, especially in heap leach pads. Oxidation chemically modifies the mineral surface altering its interface, and thereby affecting the bacteria-mineral interaction, mineral reactivity and leaching velocity. Given that the mineral can be found in different oxidation states in heap bioleaching processes, three oxidation conditions of FeS2, in which iron and/or sulfur related compounds are formed on the mineral surface were assayed. This paper studies the interaction between the modified surface of a sulfide mineral, FeS2, and 0 K culture medium, typically used in biomining processes. Chemical and electrochemical changes on surfaces were characterized by subjecting them to weathering in an acidic culture medium (pH 1.8), without applying potential or current. The chemical species formed were identified by Raman spectroscopy. The modified pyrite surfaces showed significant interfacial transformations upon immersion in the culture medium, and the formation of passive chemical species, such as elemental sulfur, jarosite, phosphates and oxides, were identified. These interfacial modifications are correlated with changes in the open circuit potential (OCP) values during immersion of pyrite and surface modified pyrites in 0 K culture medium. Electrochemical characterization showed a decrease in mineral oxidation capacity, which directly affects the extent of leaching and possibly, of the interaction with other elements participating in the process, such as microorganisms.Graphical abstractUnlabelled Image
  • Polyethylenimine-coated biomass-chitosan composite fibers for recovery of
           ruthenium from industrial effluents: Effects of chitosan molecular weight
           and drying method
    • Abstract: Publication date: Available online 5 November 2018Source: HydrometallurgyAuthor(s): Myung-Hee Song, Jeong Ae Kim, Wei Wei, Sok Kim, Yeoung-Sang Yun Sustainable recovery of precious metal ions from secondary sources is of high interest due to their limited availability, high demand, and high cost. The objective of this study was to establish manufacturing conditions of acid-stable and high-performance composite fibers and to apply the fibers for recovery of ruthenium from industrial effluents generated from acetic acid making Cativa™ process. The polyethylenimine-coated onto biomass-chitosan composite fibers (PBCFs) were prepared by different methods. The molecular weight of chitosan and drying methods were selected major factors affecting the stability and adsorption performance of PBCFs. The drying method largely affects the stability and adsorption performance, while the effect of molecular weight was not significant. After adsorption, Ru was successfully recovered as a solid state by incineration of the Ru-loaded PBCFs. The present study provided optimized conditions for fabricating stable and high-performance PBCFs able to be used for recovery of Ru through the adsorption-incineration technique.Graphical abstractUnlabelled Image
  • The effect of calcium sulfate crystallization and the crystal modification
           on aqueous REE stability in Ca saturated REE-Ca-SO4-H2O systems
    • Abstract: Publication date: December 2018Source: Hydrometallurgy, Volume 182Author(s): Farzaneh Sadri, Rina Kim, Zhi Yang, Ahmad Ghahreman Impurity removal is a key stage in the hydrometallurgical processing of rare earth elements (REE), which is performed after water leaching of the acid baked REE concentrate. 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 co-precipitation of REE with calcium sulfate dihydrate (CaSO4·2H2O, CSD), which results in a significant REE loss, renders this process inefficient. A feasible route to eliminate or minimize the REE loss associated with the lime neutralization process is to use a crystal habit modifier to alter the crystalline morphology and surface properties of CSD and subsequently reduce the portion of REE loss to the CSD. In this study, cetryltrimethylammonium bromide (CTAB) and polyacrylic acid (PAA) as cationic and anionic modifiers were employed at different concentrations of 0.2, 2 and 5 g/L to reduce the REE loss to CSD in a titration process simulating the impurity removal step. In addition, the effect of temperature and Ca(OH)2 pulp density on the co-precipitation process and morphology changes were investigated. It was observed that the cationic modifier (CTAB) reduced the fraction of REE that co-precipitate with CSD and 2 g/L CTAB was chosen as the optimum dosage of CTAB. However, the anionic modifier (PAA) deteriorated the process by helping an average of about 70% of REE to co-precipitate with CSD at low pH values (1-5). ζ-potential analysis on the precipitates revealed a more negative surface charge in the precipitates obtained from the PAA-containing solution and a less negative surface charge in the precipitates from CTAB-containing solution compared to the no-additive experiments that explains the mechanism of co-precipitation of positively charged trivalent REE ions with CSD crystals. Increasing the precipitation process temperature from 25 to 50 °C resulted in a slight increase in the fraction of REE loss and further increase in the temperature up to 70 °C resulted in a lower REE loss compared to 50 °C. Similarly, increasing pulp density of the Ca(OH)2 slurry from 0.5 to 10% showed an increase in the fraction of REE loss to CSD by changing the supersaturation of the system. Effect of all the parameters under investigation on the morphology changers of CSD crystals were studied by HR-SEM and the elemental composition of the precipitates were probed by XPS analysis.Graphical abstractUnlabelled Image
  • Investigations on the hydrolysis behavior of AlN in the leaching process
           of secondary aluminum dross
    • Abstract: Publication date: Available online 3 November 2018Source: HydrometallurgyAuthor(s): Qi Li, Qun Yang, Guofan Zhang, Qing Shi In this paper, the hydrolysis behavior of AlN in the leaching process of secondary aluminum dross was studied through thermodynamic analysis, leaching tests, X-ray Fluorescence (XRF), X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). The effects of reaction temperature and time on the AlN hydrolysis process in deionized water were studied. The leaching results showed that the solution pH and nitride change increased with the increase of leaching temperature and time. The XRD and SEM results showed that the morphology of hydrolysis process includes the AlN surface exposure, the form of amorphous aluminum hydroxide, boehmite, and precipitation of bayerite. The thermodynamic calculation demonstrated that the hydrolysis of AlN could proceed spontaneously. For practical significance, AlN can easily hydrolyze because of the moist air and exothermic chemical reactions, especially in summer which the ambient temperature is pretty high. Taking the environmental impact into consideration, the dross can be pretreated by water leaching to decompose the AlN before landfilling.
  • Process mineralogy of refractory gold ore in thiosulfate solutions
    • Abstract: Publication date: Available online 1 November 2018Source: HydrometallurgyAuthor(s): Juan D. Ospina-Correa, Erica Mejía-Restrepo, Carlos M. Serna-Zuluaga, Alejandro Posada-Montoya, Juan G. Osorio-Cachaya, José A. Tamayo-Sepúlveda, Jorge A. Calderón-Gutiérrez A mineralogical characterization was carried out in samples of refractory gold ore with 59 g/ton, according to fire assays, which were taken from a previous leaching process with ammonium thiosulfate. The potential window used to evaluate the cathodic and anodic processes was chosen knowing that gold and copper reduction, and thiosulfate and Cu(I) species oxidation occurs in it. The leaching process consisted of a pretreatment of the mineral (in ammonium hydroxide and copper sulfate during 12 h with and without air bubbling) followed by leaching (in ammonium thiosulfate solution and EDTA at a pH ∼ 10 during 24 h with mechanical stirring at a rate of 250 rpm) which rendered a gold-release of 81.57%. When oxidants and stabilizers like Cu(II), NH3 and EDTA are present in thiosulfate based leaching solutions, the chemistry turns complex, and the partial reduction of copper, and redissolution of gold may occur. This fact and the low gold concentration make the electrowinning process especially difficult. Characterization techniques such as polarized light microscopy, X-Ray Diffraction, Rietveld quantification, and Automated Digital Imaging System, were chosen to track the process mineralogy of the sample, and the results prior to the leaching revealed association, size, and shape of each mineral occurrence; it was found that the mineral composition was pyrite crystals, exhibiting subhedral and inequigranular morphology (75%); galena crystals (10%); sphalerite (1.8%); chalcopyrite and arsenopyrite crystals ( M3> sphalerite. Rietveld quantification suggested changes in the ratio of the main phases: pyrite decreased from 75.6% up to 65.7%; quartz increased from 21.1% up to 31.3%; galena decreased from 10.4% up to 7.6%; sphalerite decreased from 1.8% up to 1.1%.. It is worth saying that the presence of precipitated amorphous phases was not observed.Graphical abstractUnlabelled Image
  • Co+composite+anode+during+Zinc+electrowinning&rft.title=Hydrometallurgy&rft.issn=0304-386X&">Electrochemical performance of PbCo composite anode during Zinc
    • Abstract: Publication date: Available online 1 November 2018Source: HydrometallurgyAuthor(s): Maryam Karbasi, Eskandar Keshavarz Alamdarib, Elaheh Amirkhani Dehkordia In this study, the electrochemical and anodic behaviors of CoPb anodes in electrowinning process were investigated. Accumulative roll bonding (ARB) method was applied to fabricate CoPb composites. The electrochemical properties of the produced anodes were investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry technique (CV), electrowinning tests, and scanning electron microscopy (SEM). The results indicated that ARB-process is an appropriate method to developed CoPb anodes. The produced anodes containing 0.5% of Cobalt particles as a second phase after 10 cycles of ARB process which is named Pb-0.5%Co-10pass samples showed 83.37% increase in current density compared to pure lead anode. The results of electrowinning tests revealed that Pb-0.5%Co-10pass samples had the best anodic performance with a significant lower corrosion rate, product and electrolyte contamination, slime formation, energy consumption and a higher Zn deposit as a product and energy conservation.
  • The electrochemistry and kinetics of the oxidative dissolution of
           chalcopyrite in ammoniacal solutions: Part I – Anodic Reactions
    • Abstract: Publication date: Available online 30 October 2018Source: HydrometallurgyAuthor(s): T. Moyo, J. Petersen, M.J. Nicol The oxidative dissolution of chalcopyrite in aqueous solutions is an electrochemical process. Such processes can be evaluated as coupled anodic and cathodic reactions using electrochemical techniques. The chalcopyrite dissolution reaction has been studied in ammonia-ammonium sulphate solutions using potentiostatic and potentiodynamic methods. Anodic current densities in the vicinity of the mixed potential have been found to increase with an increase in total ammonia (NH3 + NH4+) from 1 M to 3 M, and the order of reaction was found to be 1st order with respect to ammonia. The reaction was found to be zero order with respect to [OH−] at a pH between 9 and pH 10. An analysis of the Tafel slopes suggested an average charge transfer coefficient of 0.61. The rate controlling step was concluded to be a single electron transfer reaction, which supports the formation of a copper depleted intermediate surface that is rapidly oxidised in subsequent electron transfer reactions. The anodic sweeps and constant potential tests did not support the formation of a passivating surface deposit on the oxidising chalcopyrite surface.
  • Kinetic study of copper leaching from chalcopyrite concentrate in alkaline
           glycine solution
    • Abstract: Publication date: Available online 29 October 2018Source: HydrometallurgyAuthor(s): Doyun Shin, Junmo Ahn, Jaeheon Lee Recently, glycine, one of the simplest amino acids, has been emerging as an efficient and environmental-friendly lixiviant for copper leaching. In the present study, an alkaline glycine–peroxide lixiviant system was used to leach copper from chalcopyrite concentrate by a suite of kinetic studies under different conditions. The particle size of the concentrate was P80 40 μm. Glycine concentration was varied from 0.5 to 3.0 M (glycine to copper molar ratio of 1.1 to 6.6:1) and the pH was maintained at 11 during the experiment. The copper extraction within 96 h was observed from 13 to 14% with glycine concentrations from 0.5 to 2 M, while the copper extraction decreased at 3 M of glycine. By reconstituting the glycine concentration during the leach test and adding hydrogen peroxide periodically, the copper extraction with 1 M glycine at 96 h increased from 14 to 21%, respectively. By changing the glycine and hydrogen peroxide solution every 24 h, 42% of copper extraction was achieved within 168 h. With increasing temperature, copper extraction decreased, while iron dissolution increased. Copper sulfide and copper sulfate precipitates were found in the leaching liquor at 22 °C test. Poorly crystalline copper-iron sulfate phase was observed in the leaching liquor at 35 and 45 °C. This precipitation is believed to be one of the factors to decrease the copper recovery from chalcopyrite.
  • The adsorption of gold(I) on minerals and activated carbon (preg-robbing)
           in non-ammoniacal thiosulfate solutions - effect of calcium thiosulfate,
           silver(I), copper(I) and polythionate ions
    • Abstract: Publication date: Available online 24 October 2018Source: HydrometallurgyAuthor(s): O. Sitando, G. Senanayake, X. Dai, P. Breuer The ability of some typical gangue minerals and activated carbon to adsorb gold(I) (preg-robbing) in non-ammoniacal thiosulfate solutions was examined at different calcium thiosulfate concentrations. In the absence of calcium thiosulfate, sulfide minerals such as pyrite and chalcopyrite, and carbon were highly preg-robbing with 100% gold being adsorbed within half an hour. The oxide minerals examined including kaolinite, goethite and hematite were significantly less preg-robbing under the same conditions. The presence of free thiosulfate can significantly reduce or eliminate the preg-robbing of gold on mineral surfaces. With an initial thiosulfate concentration of 0.1 M, gold adsorption by oxide minerals was completely eliminated, while that of sulfide minerals and carbon was insignificant at 0.2 M free thiosulfate.Copper(I) was found to enhance the preg-robbing of gold by oxide minerals but to reduce the preg-robbing of gold by sulfide minerals and by carbon. Similar effect of silver(I) was observed except for chalcopyrite. Trithionate, a by-product of thiosulfate degradation, has no significant effect on the preg-robbing of gold(I). Tetrathionate, another by-product of thiosulfate degradation, significantly increases the preg-robbing of gold(I) onto pyrite. Activated carbon enhances the degradation of tetrathionate to trithionate and thiosulfate, the latter helps stabilise the gold(I) in solution.
  • Fungal treatment of lignites with higher ash and sulphur contents using
           drum type reactor
    • Abstract: Publication date: Available online 23 October 2018Source: HydrometallurgyAuthor(s): Büşra Şener, Derya Öz Aksoy, Pınar Aytar Çelik, Yağmur Toptaş, Sabiha Koca, Hüseyin Koca, Ahmet Çabuk Biological desulphurization is a good option because of simple equipment, easy operation, and low cost advantages. In this study, biodesulphurization of low rank lignites having high ash and sulphur content was investigated through a drum reactor using Alternaria sp. fungus which provided high removal of sulphur at erlen scale in our previous study. Designing of experiments, analysing of experimental results, creating the mathematical models and optimization of conditions were performed using Central Composite Design Method. Experimental work resulted in about 20% sulphur removal, about 21% ash removal and about 42% reduction in sulphur emission values. Analyses showed that both pyritic (17% removal) and organic sulphur (about 19% removal) were reduced. Besides, after biotreatment, FTIR, SEM-EDS, TGA-DTA analysis as well as volatile matter and major oxide analysis were carried out. Furthermore, data for increasing sulphur removal in drum type bioreactor and moving to larger scale by enhancing solid ratio were provided.Graphical abstractUnlabelled Image
  • Enhanced selective leaching of scandium from red mud
    • Abstract: Publication date: Available online 16 October 2018Source: HydrometallurgyAuthor(s): Kanggen Zhou, Chunying Teng, Xuekai Zhang, Changhong Peng, Wei Chen Selective leaching of Sc from red mud is particularly important for both solid waste treatment and reclamation of rare earth elements. This work developed a new method for selective acid leaching of Sc and Fe from red mud. Ethylene diamine tetraacetic acid (EDTA) was chosen as the chelating agent to re-distribute the species of Sc and Fe ions in the leaching process, which greatly enhanced the selectivity of Sc over Fe. EDTA–enhanced selective leaching of Sc from red mud using diluted hydrochloric acid was achieved under the optimal experimental conditions: ratio of leaching agent (HCl + H2O): red mud: EDTA was 40 mL: 10 g: 2 g, and HCl dosage was 40% of theoretical value at temperature 70 °C and reaction time 4.0 h. The leaching efficiencies of Sc and Fe were 79.6% and 6.12% respectively. The Sc/Fe leaching efficiency ratio was greatly improved with the involvement of EDTA, which made the subsequent separation of Fe and Sc easier. Furthermore, this work may provide an alternative way for the recovery and separation of valuable metals from solid wastes.Graphical abstractUnlabelled Image
  • A review of recent studies into hydrometallurgical methods for recovering
           PGMs from used catalytic converters
    • Abstract: Publication date: Available online 16 October 2018Source: HydrometallurgyAuthor(s): Collins Saguru, Sehliselo Ndlovu, Desiree Moropeng Demand for the 3 PGMs - platinum, palladium and rhodium has been steadily increasing, largely as a result of the growing use of the metals in autocatalytic converters. Due to the challenges in the PGM mining industry, studies to recover PGMs from autocatalytic converters have been increasing. In this regard, hydrometallurgical and pyrometallurgical processes have dominated the research field, with pyrometallurgical processes enjoying widespread adoption in the autocatalytic converter recycling industry. However, pyrometallurgical based processes are expensive, require specialized equipment, are highly energy consuming and produce toxic combustion products. Hydrometallurgical processes do not suffer from some of these problems and in that regard, may be favourable for recycling auto converters. Furthermore, the use of less toxic, less flammable extractants like ionic liquids for recovering the PGMs out of solution presents benefits in terms of increased recoveries and safety of operating conditions. Studies for the recycling of PGMs by leaching and extraction have therefore been increasing, and the use of novel extractants like ionic liquids has also been investigated in the literature.
  • Desilication of concentrated alkali solution by novel desilication reagent
           calcium hydroferrocarbonate: Part I. Synthesis of desilication reagent
    • Abstract: Publication date: Available online 15 October 2018Source: HydrometallurgyAuthor(s): Tao Hong, Ying Zhang, Manbo Liu, Shili Zheng, Yi Zhang For the deep removal of silica from sodium aluminate solution with a high alkaline concentration, we propose novel ferrite desilication reagents calcium hydroferrocarbonate (CHFC; 3CaO·Fe2O3·CaCO3·12H2O) because Fe3+ cations show extremely low solubilities of ~1–3 mg/L in highly concentrated caustic solutions. The main factors affecting the synthesis of CHFC were studied, including time, temperature, liquid-to-solid mass ratio, and particle size of CaO. The results showed that CHFC is a metastable material in the alkaline solution, and the synthesis factors, time and temperature, are related to each other. The optimum synthesis conditions of CHFC were determined. The mechanisms in the synthesis of CHFC, and the desilication mechanism by CHFC, are discussed, using the desilication reaction and X-ray Diffraction analysis. In the desilication process, silica combines with CHFC to form calcium hydroferrosilicate, calcium hydroferroaluminosilicate and.calcium ferroaluminosilicate.
  • Electrochemical behaviour and surface analysis of chalcopyrite in alkaline
           glycine solutions
    • Abstract: Publication date: Available online 15 October 2018Source: HydrometallurgyAuthor(s): G.M. O'Connor, K. Lepkova, J.J. Eksteen, E.A. Oraby Electrochemical experiments with a chalcopyrite rotating disk electrode were carried out in alkaline glycine solutions. This showed no apparent passivation behaviour during anodic dissolution that is observed in acid solutions. The current increased with applied potential from the open circuit potential with no resemblance to the passivation region seen in acid solutions. A loosely held porous layer developed on the surface consisting largely of iron oxyhydroxides that had a limited effect on the anodic current. Elemental sulfur and a disulfide species were detected using XPS and Raman spectroscopy but did not passivate the surface as has been proposed for acid solutions. The disulfide species is sometimes used to infer a metal deficient sulfide or polysulfide that is responsible for passivation but in this study it had no passivating influence. Current-potential curves showed features of a non-ideal semiconductor that were explained by charge transfer via surface states.
  • Resin-enhanced acid leaching of tungsten from scheelite
    • Abstract: Publication date: Available online 15 October 2018Source: HydrometallurgyAuthor(s): Dandan Gong, Kanggen Zhou, Changhong Peng, Dewen He, Wei Chen Leaching of tungsten from scheelite is critical for the reclamation of tungsten resources. Conventional approaches for tungsten leaching involve the problems of low efficiency, sophisticated equipment demand, or complicated follow-up issues. In this study, a resin-enhanced acid leaching method was developed for the rapid extraction of tungsten from both natural scheelite and synthetic scheelite. Herein, 732 resin was used to accelerate the leaching process and increase the leaching yield of tungsten through the adsorption of Ca2+ and the release of H+. The leaching process was significantly affected by acid concentration, resin dosage, liquid-to-solid ratio, and temperature. Furthermore, the leaching reaction followed the chemical reaction-controlled kinetics, and tungsten was extracted in the form of isopoly-tungstic acid. This study may provide a cost-effective alternative for the rapid decomposition of scheelite under relatively low temperature conditions.Graphic abstractUnlabelled Image
  • Solvent extraction of zinc from chloride solutions using dialkyl
           derivatives of 2,2′-bibenzimidazole as extractants
    • Abstract: Publication date: Available online 10 October 2018Source: HydrometallurgyAuthor(s): Iwona Mądrzak-Litwa, Aleksandra Borowiak-Resterna Four new 1,1′-dialkyl-2,2′-bibenzimidazoles were used to extract zinc(II) from acid chloride solutions at various concentrations of chloride and hydrogen ions. In low acidity media (pH > 2), the maximum zinc(II) extraction with the compounds is observed at chloride concentrations in the range 0.7–1.8 M. Zinc(II) ions are extracted as neutral (ZnCl2)mLn complexes (L = extractant) in which the m:n ratio varies from 1:2 to 3:3, depending on the metal-to-extractant molar ratio in the extraction media. In strongly acidic systems, anionic zinc(II) chloro-complexes may be extracted from aqueous solutions by protonated bibenzimidazoles as (LH+)2(ZnCl42−) or/and (LH+)(ZnCl3−) ion pairs. In weakly acidic media, at [Cl−] 
  • The separation of Ni(II) over base metal ions in acidic polymetallic
           medium: Synergistic extraction and structural evidence
    • Abstract: Publication date: Available online 8 October 2018Source: HydrometallurgyAuthor(s): Fang Hu, Huiping Hu, Yuqing Luo, Yongxi Wang, Jinpeng Yang, Jiugang Hu The selective extraction of Ni(II) from a polymetallic solution was achieved with an extractant mixture containing dinonylnaphthalene disulfonic acid (H2DNNDS) and 2-ethylhexyl 4-pyridinecarboxylate ester (4PC, LII). The equilibrium results indicated that Ni(II) extraction was sensitive to the molar fraction of 4PC in the mixture containing H2DNNDS and 4PC. It was found that individual H2DNNDS or 4PC resulted in low extraction efficiency of Ni(II). Interestingly, when the mole fraction of 4PC in the mixture surpassed 50%, significant synergistic effect was observed for Ni(II) separation over Fe(III), Al(III), Ca(II), Mg(II) and Mn(II), thus highlighting the synergistic role of 4PC. In order to provide structural evidence for synergistic mechanism, two nickel model complexes were synthesized with 1,5-naphthalene disulfonic acid (H2NDS) in the absence/presence of methyl isonicotinate (LI), which were the corresponding short-chain analogues of H2DNNDS and 4PC, respectively. Combined with single crystal X-ray diffraction of nickel model complexes, the coordination chemistry of nickel complex in the loaded organic phases was disclosed with the Fourier Transform infrared spectroscopy (FT-IR) and electrospray ionization mass spectrometry (ESI-MS). The results showed that Ni(II) was directly coordinated with two monodentate ligands LI and four water molecules, while no direct interaction existed between Ni(II) and the O atoms of the deprotonated H2NDS in both two nickel model complexes. Hydrogen-bonding interaction between the H atom of coordinated water and the O atom of the deprotonated H2NDS played important role in stabilization of coordination configuration. The selective extraction of Ni(II) might be attributed to the incorporation of the pyridine based nitrogen donor into the inner coordination sphere of Ni(II) to supplant coordinated water.Graphical abstractUnlabelled Image
  • Enhancing decontamination of zirconium and ruthenium in the Thorex process
           using acetohydroxamic acid
    • Abstract: Publication date: Available online 8 October 2018Source: HydrometallurgyAuthor(s): Zheng Li, Haogui Zhao, Mumei Chen, Qingnuan Li, Lan Zhang The decontamination of some extractable fission products, such as Zr and Ru, is an important issue in the Thorex process. Acetohydroxamic acid (AHA) is an organic ligand composed of only C, H, N and O atoms. It can be used as complexing and reducing agent to inhibit the extraction of Zr and Ru. In this paper, the effect of AHA and preheating on the extraction of Th, U, Zr and Ru was studied. It is found the extraction of Zr and Ru would be inhibited in the presence of AHA and preheating, meanwhile there was no obvious effect on the extraction of Th and U. Afterwards, the countercurrent extraction using centrifugal extractors was performed to further test and verify the effect of AHA in a typical Thorex process. The results indicate that the decontamination of Zr and Ru could be enhanced evidently due to the effect of AHA, and the corresponding decontamination factor would be improved from 27.0 to 3.3 × 103 and 111.0 to 1.5 × 103, respectively. Thus, the use of AHA would be an efficient means for enhancing the decontamination of Zr and Ru in Thorex process.
  • Optimizing vanadium and tungsten leaching with lowered silicon from spent
           SCR catalyst by pre-mixing treatment
    • Abstract: Publication date: Available online 6 October 2018Source: HydrometallurgyAuthor(s): Su Qingfa, Miao Jifa, Li Huirong, Chen Yanting, Chen Jinsheng, Wang Jinxiu In this paper, the leaching behaviors of vanadium (V), tungsten (W) and silicon (Si) from spent SCR (selective catalytic reduction) catalyst were evaluated and a pre-mix treatment to enhance V-W leaching with low Si leaching at 25°C and atmosphere pressure was developed. The effects of leaching factors were investigated systematically by two orthogonal array experiments, and then experiments with a single variable factor of NaOH concentration and temperature were carried out, respectively. Alkali, especially NaOH, is the best reagent for V and W simultaneous leaching from spent SCR catalyst. Increasing temperature or NaOH/catalyst ratios enhances V and W leaching rates. 68.3% V leaching rate and 50.1% W leaching rate were obtained under an optimal conditions (temperature 100°C, NaOH/catalyst ratio 0.9, L/S 15, stirring speed 900 rpm and time 240 min). However, the W/Si concentration ratio under this condition, as low as 1.4, is unacceptable from the view of separation and economy. A proposed pretreatment process, in which NaOH and catalyst was pre-mixed, decreases time consuming to 20 min and lowers temperature to 25°C but obtains higher W/Si concentration ratio 7.0 and almost the equal leaching rate (67.7% for V and 56.3% for W).
  • Mathematical modeling of the dissolution of phosphate rock into various
           acidic medium
    • Abstract: Publication date: Available online 5 October 2018Source: HydrometallurgyAuthor(s): Arbi Mgaidi, Hichem Mokni The leaching of phosphate ores in acid medium is widely practiced in the chemical fertilizers industry. Several processes can take place in the reactor and the quantitative modeling of the reaction kinetics or thermodynamics is essential for the design and dimensioning of the industrial equipments. The aim of the present study is to develop a mathematical model to describe the behavior of phosphate particles into acidic solution under certain conditions. A new formalism based on the Noyes-Whitney equation (NWE) is presented in this paper. In this approach, simplified Lucas-Washburn's equation (LWE) is incorporated to evaluate the progression of reaction zone into the mesoporous phosphate rock. The reliability and validity of this new approach are tested on a large database. Results show that the model is predictive in the case of a solid dissolution without ash film and non predictive in the case of solid leaching with formation of a rushed in the mesoporous area follows. Furthermore, the values and physical significance of the parameters of this model are also discussed in the present work.
  • Leaching of chalcopyrite ore agglomerated with high chloride concentration
           and high curing periods
    • Abstract: Publication date: Available online 5 October 2018Source: HydrometallurgyAuthor(s): L. Velásquez-Yévenes, David Torres, Norman Toro It is well known that the leaching of chalcopyrite has very slow kinetics. The generally higher reactivity of chalcopyrite in chloride as opposed to sulfate solutions has resulted in many studies of chloride systems for the hydrometallurgical treatment of chalcopyrite. Despite much progress on the chloride leaching process, agglomeration and curing has received less attention over the past years. This paper reports a study on the effect of addition of chloride ion in the agglomeration and the effect of curing time on the overall leaching process of chalcopyrite ore. The work involved leaching tests carried out in columns containing 3.0 kg of agglomerated ore irrigated with raffinate solution under ambient conditions. Experiments with agglomerates produced at different concentration of chloride (20, 50 and 70 kg/t) leach at approximately the same rate. It has been demonstrated that chloride ions presence is necessary to improve the leaching kinetics, but high concentrations of chloride are not essential under ambient conditions. The rate of dissolution of chalcopyrite ore agglomerated with high concentrations of acid and chloride ions increases as the curing period increases from 15 to 80 days observing extraction of copper up to 60% in 20 days of leaching. In all experiments, the shape of the leach curves indicate that the copper that has been solubilized during the curing period is rapidly leached followed by continuous slow leaching thereafter. This study supports the addition of chloride at the agglomeration stage as a viable route for the treatment of low-grade copper sulfide ore.
  • Electrochemical behaviour of copper in alkaline glycine solutions
    • Abstract: Publication date: Available online 4 October 2018Source: HydrometallurgyAuthor(s): G.M. O'Connor, K. Lepkova, J.J. Eksteen, E.A. Oraby The fundamental electrochemical properties of the copper-glycine system were investigated in this study to understand the factors that affect the dissolution of metallic copper. Potentiodynamic polarisation measurements were carried out over the pH range 9.0 to 11.5, at temperatures of 22 °C and 60 °C and glycine concentrations 0.1 M and 0.3 M. A window for maximum corrosion current was determined to be between pH 10.0 and 10.5 with a maximum at 60 °C and 0.3 M glycine. Passivation was only observed at pH values>10.5, and then only at potentials above 0.4 V (vs SHE) for quiescent solutions. This passivation potential increased with the rotation speed of the copper electrode. The passive layer broke down after a short rest at the open circuit potential, which allowed reactivation of the surface and high initial currents to briefly flow until the layer re-formed. Potential-step and capacitance measurements are consistent with the formation of a duplex oxide layer of Cu2O and CuO that thickens with increasing potential. The copper glycinate complex itself also acts as an oxidising agent, the effectiveness is increased with its concentration and the concentration of free glycine. Free glycine is oxidised irreversibly above 1.2 V (vs SHE).
  • Recovery of Zr, Hf, Nb from eudialyte residue by sulfuric acid dry
           digestion and water leaching with H2O2 as a promoter
    • Abstract: Publication date: Available online 4 October 2018Source: HydrometallurgyAuthor(s): Yiqian Ma, Srecko Stopic, Lars Gronen, Bernd Friedrich Following the initial hydrometallurgical extraction of rare earth elements from the eudialyte mineral, the residue is known to contain additional valuable metals. In this reported study, a two-stage acidic treatment was investigated to extract Zr, Hf, Nb from the eudialyte residue. The objective was to obtain high recovery yields with a low consumption of acid, so the proposed preprocessing step was sulfuric acid dry digestion, which was held above the boiling point of water. The treated residue was then leached with water and H2O2 was added to promote the leaching of Zr, Hf and Nb. It was found that the H2O2 increased the oxidation potential of the acidic system, which assisted the decomposition of the mineral phases that contained Zr, Hf and Nb. In addition, the H2O2 acted as a reaction promoter by providing O22– ions that formed complexes with the cations, shifted the reaction equilibrium and inhibited hydrolysis of Nb(IV). The QEMSCAN, XPS and SEM analysis were used to reveal the mineralogical characteristics of the solid samples. These characteristics demonstrated the chemical changes that occurred during extraction and helped to explain the mechanisms at work during the processes. The SEM analysis results showed that metals sulfate salts and quartz were present after the digestion process. The treated eudialyte residue leached the soluble salts into solution, whereas the quartz remained in the residue. After optimizing the treatment parameters by varying the process conditions it was found that the eudialyte extract produced 89.1% Zr, 81.2% Hf and 71.2% Nb and the most suitable process parameters were: digestion conditions: H2SO4/eudialyte residue: 25 ml/100 g, water/eudialyte residue: 20 ml/100 g, 110 °C, 4 h; leaching conditions: L/S: 3:1, H2O2/eudialyte residue: 10 ml/100 g, room temperature, 1 h.
  • A study of the electro-assisted reductive leaching of a chalcopyrite
           concentrate in HCl solutions. Part I: Kinetic behavior and nature of the
           chalcopyrite reduction
    • Abstract: Publication date: Available online 1 October 2018Source: HydrometallurgyAuthor(s): V.J. Martínez-Gómez, J.C. Fuentes-Aceituno, R. Pérez-Garibay, Jae-Chun Lee This first part of research presents an analysis of the electro-assisted reductive leaching (ERL) of refractory chalcopyrite (CuFeS2) performed in HCl media using an electrolytic cell operated at room temperature and pressure. This is as an alternative approach to decrease the passivation phenomenon observed in the ERL process with sulfuric acid, which favored the chalcopyrite reduction kinetics at pulp densities>10 g/L. Different variables were optimized to understand the electro-reduction kinetics of chalcopyrite such as: acid concentration, current density and pulp density. The reaction mechanism proposed was complemented with the electrochemical techniques, and SEM-EDS and X-ray diffraction analyses. The results revealed that electro-reduction of chalcopyrite performed in HCl at a pulp density of 100 g/L present a higher reduction rate than that of the sulfuric acid system. From a mechanistic viewpoint, chalcopyrite can be sequentially reduced to chalcocite and metallic copper, respectively. The latter is a very reactive species which can be easily oxidized in the presence of air and remaining hydrochloric acid, to cuprous hydroxychloride or atacamite species (Cu2Cl(OH)3) and cuprite (Cu2O) when the solid residue is withdrawn from the reactor. These copper species are highly soluble in aqueous solutions which can permit the recovery of copper. From an energetic viewpoint, the energy consumption of the HCl electrolytic system is lower than that of the H2SO4 electrolytic system.
  • Separation of cobalt and nickel in leach solutions of spent nickel-metal
           hydride batteries using aqueous two-phase systems (ATPS)
    • Abstract: Publication date: Available online 24 September 2018Source: HydrometallurgyAuthor(s): Alberto Valadares, Clara França Valadares, Leandro Rodrigues de Lemos, Aparecida Barbosa Mageste, Guilherme Dias Rodrigues This paper presents the use of an aqueous two-phase system (ATPS) as an alternative to liquid–liquid solvent extraction for the selective removal of cobalt and nickel from nickel metal hydride batteries (NiMH). The optimized extraction conditions were determined with a leach liquor obtained from the NiMH battery residue as a matrix. The effect of several key variables on the metal extraction was evaluated: (i) extractant nature, (ii) pH, (iii) the ATPS-forming electrolyte, (iv) the ATPS-forming copolymer, (v) the ratio between the top and bottom phases, and (vi) liquor dilution. Process efficiency was measured by the percentage of cobalt (%ECo) and nickel (%ENi) extraction and the separation factor between these metallic ions (βCo/Ni). The highest cobalt extraction percentages were obtained for ATPS formed by L64 + Na2SO4 + H2O at pH 5.00, using 1-nitroso 2-naphtol (1N2N) extractant and a liquor dilution factor of 35. At these conditions, %ECo and %ENi were 99.18% and 1.29%, respectively, and βCo/Ni reached 9339 after three successive extraction steps.Graphical abstractUnlabelled Image
  • Increasing cell concentration does not affect specific ferrous iron
           oxidation rate in a continuously stirred tank bioreactor
    • Abstract: Publication date: Available online 20 September 2018Source: HydrometallurgyAuthor(s): Naomi J. Boxall, Ka Yu Cheng, Chris A. du Plessis, David Collinson, Christina Morris, Natalia Streltsova, Brigitte Seaman, David Seaman, Luke Vollert, Anna H. Kaksonen Microbial oxidation of ferrous to ferric iron allows efficient oxidative processing of sulfide minerals under ambient conditions. This study determined the effect of cell concentration of a mixed mesophilic microbial culture on iron oxidation rate, and evaluated if there was a cell concentration threshold that dictates a maximal volumetric iron oxidation rate. A bioreactor with feedback-loading of ferrous media was operated at 30 °C to maintain a redox potential of +480 mV vs. Ag/AgCl at pH of 1.3. A positive and linear correlation (R = 0.955) between the cell concentration (6.8 × 107–7.1 × 109 cells mL−1) and volumetric biological iron oxidation (up to 6.9 g L−1 h−1) was observed. The specific iron oxidation was not affected by cell concentration, and no biocatalytic threshold was observed. This indicated that a high cell concentration can be used to achieve a high volumetric iron oxidation rate, enabling the use of a compact reactor size.
  • Recovery of ruthenium by solvent extraction and direct electrodeposition
           using ionic liquid solution
    • Abstract: Publication date: Available online 20 September 2018Source: HydrometallurgyAuthor(s): Yueqi Song, Yusuke Tsuchida, Masahiko Matsumiya, Katsuhiko Tsunashima It is important to recover Ru metal from spent target materials including Pt, Co and Cr. The extraction behavior using Di-(2-ethylhexyl)phosphoric acid (HDEHP) and ionic liquid (IL), triethyl-n-pentyl phosphonium bis(trifluoromethyl-sulfonyl)amide; [P2225][TFSA] diluent was investigated with pH dependence. Co(II) and Cr(II) were selectively extracted into the organic phase because the extraction of Co(II) and Cr(II) proceeded by cation exchange. As a result, Pt(IV) and Ru(III) can be separated from Co(II) and Cr(II) by controlling the pH. Moreover, the extraction mechanism of Ru(III) with the Alamine336 (A336)/[P2225][TFSA] system was based on the following anion exchange reaction; [R3NH+Cl−]org + [RuCl4(H2O)2−]aq ⇔ [R3NH+RuCl4(H2O)2−]org + [Cl−]aq, (R = CH3(CH2)7-/CH3(CH2)9-).The electrochemical behavior for Ru(III) in the [P2225][TFSA] was investigated by cyclic voltammetry at 373 K. It was revealed that two step cathodic reactions: Ru(III) + e− → Ru(II) and Ru(II) + 2e− → Ru(0) were proceeded in the [P2225][TFSA] system. Moreover, the potentiostatic electrodeposition allowed us to recover the blackish electrodeposits, which were identified as most of Ru metal by EDX analysis. Finally, we investigated the reuse of the Ru(III) in A336/IL solvent for continuous extraction and electrodeposition. The extraction percentage of Ru(III) using A336/IL remained relatively high (81.5–96.1%) for the 1st − 5th cycles. This series of experimental results enabled us to demonstrate that Ru metal can be obtained from direct electrodeposition of the extracted [R3NH+RuCl4(H2O)2−] in the A336/[P2225][TFSA] system.
  • Extraction and separation studies of rare earth elements using Cyanex 272
           impregnated Amberlite XAD-7 resin
    • Abstract: Publication date: Available online 19 September 2018Source: HydrometallurgyAuthor(s): S. İnan, H. Tel, Ş. Sert, B. Çetinkaya, S. Sengül, B. Özkan, Y. Altaş As a part of technological evaluation of Eskisehir-Beylikahir thorium–Rare Earth Elements (REEs) ore of Turkey, a novel study investigating the extraction behaviours of light REEs for Cyanex 272 impregnated Amberlite XAD–7 resin was carried out. Solvent impregnated resin (SIR) was prepared by the impregnation of kerosene diluted Cyanex 272 onto Amberlite XAD–7 resin. SIR was characterized by FTIR, SEM, TGA–DSC, surface area and porosity analyses. The usability of Cyanex 272 impregnated XAD–7 for the extraction of La, Pr, Nd, Sm, Eu and Gd from nitric acid solution was investigated by batch experiments. Parameters affecting the uptake of these metal ions such as pH, contact time and liquid/solid (V/m) ratio were studied. Experimental data indicated that REEs have a tendency to behave as two separate groups as La, Pr, Nd and Sm, Eu, Gd. Light elements are being displaced by the heavier elements as they load up. Kinetic data fit the pseudo second order model for each element and the capacity values at the equilibrium were obtained as 11.1, 0.56, 1.69, 0.75, 0.10 and 0.25 mg g−1 for La, Pr, Nd, Sm, Eu and Gd, respectively. Complete stripping of Pr(III), Nd(III), Sm(III), Gd(III) and 95.1% of Eu(III) ions were achieved by using 0.1 mol L−1 HNO3 in one stage batch contact.
  • Selective leaching of arsenic from enargite concentrate using alkaline
           leaching in the presence of pyrite
    • Abstract: Publication date: Available online 18 September 2018Source: HydrometallurgyAuthor(s): Tengfei Li, Yansheng Zhang, Bo Zhang, Jiaming Zhang, Wenqing Qin Alkaline leaching is a promising treatment to extract arsenic from enargite. This study investigates the feasibility of leaching enargite concentrate in the presence of pyrite in alkaline solution with sodium hydroxide only. Single factor and orthogonal experiments were performed to determine the effect of sodium hydroxide concentration, temperature, leaching time and liquid-to-solid ratio on enargite dissolution and to optimize leaching conditions. The results indicate that sodium hydroxide concentration has the greatest effect on arsenic dissolution from enargite, while the liquid-to-solid ratio has the smallest effect. Finally, over 99% of arsenic was removed using optimal conditions. Characterization of the leach residue by XRD and SEM-EDS analyses showed that enargite was converted into non‑arsenic copper sulfides such as anilite (Cu7S4), geerite (Cu8S5) and djurleite (Cu31S16). This research is applicable to solving problems related to arsenic pollution.
  • Recovery of uranium, thorium and rare earth from industrial residues
    • Abstract: Publication date: Available online 17 September 2018Source: HydrometallurgyAuthor(s): Janúbia C.B.S. Amaral, Michelle L.C.G. Sá, Carlos A. Morais This paper addresses the development of a process to recovery uranium, thorium and rare earth elements from an industrial residue, with a subsequent removal of U and Th from the liquor generated. Sulfuric acid digestion followed by water leaching was found to be the best method to solubilise the metals. The acid digestion was carried out with an acid sample ratio of 700 kg t−1 and a reaction time of 2 h, without temperature control. The water leaching step was performed at room temperature (25 ± 2 °C), with 1 h of mechanical stirring and 20% of solids. Under these conditions, a metal dissolution of 94%, 81% and 97% was reached for the REE, Th and U, respectively. After the metal solubilisation, a sulfuric liquor containing 0.08 g L−1 Th, 0.35 g L−1 U, 9.1 g L−1 REE, 16 g L−1 Al, 7.8 g L−1 Fe, 0.47 g L−1 Ca, 0.75 g L−1 Zn and 0.1 g L−1 Si was formed. This liquor was used in the solvent extraction stage in order to separate Th and U from the REE, as well as from other metals. The effect of the type and extractant concentration, acidity of the liquor and type and concentration of the stripping solution were investigated. The results showed that 97% of the uranium and 94% of the thorium were extracted by a mixture of 0.05 mol L−1 of Primene JM-T and 0.1 mol L−1 of Alamine 336, in a single stage. The stripping from the loaded organic phase for the simultaneous removal of U and Th can be effectively done by using 1.7 mol L−1 NaCl solution at pH 1.2.Graphical abstractFlow sheet for the recovery of U, Th and REE from an industrial residue.Unlabelled Image
  • Investigation of the kinetics and the morphology of cementation products
           formed during purification of a synthetic zinc sulfate electrolyte
    • Abstract: Publication date: Available online 17 September 2018Source: HydrometallurgyAuthor(s): Toni Gutknecht, Yu Cao, Yuda Colombus, Britt-Marie Steenari In zinc production, the purity of incoming zinc solution is of great importance. The presence of cobalt in the electrolyte used for zinc production lowers the current efficiency of zinc deposition and affects the purity of the zinc product. For this reason, cobalt must be removed from the electrolyte prior to zinc electrowinning. Cobalt removal is commonly achieved by the addition of metallic zinc dust through a process called cementation. The mechanism by which cementation occurs is not well understood. Parameters, such as cementation time, temperature, solution pH, concentration of activators, concentration of zinc ions in the electrolyte were investigated in this study. It was concluded that cobalt cementation could be described by a first order rate equation with an activation energy of 45 kJ/mol. Temperature played a significant role on the kinetics while the presence of hydrogen, intermediate compound formation, and zinc ions inhibited the cobalt cementation. Cu/Sb activators were cemented within the first 90 s and gave synergistic effect on cobalt cementation. Surface compounds on the cementation product were identified as mainly Zn(OH)2 and ZnSO4. Redissolution of cobalt did not occur from cemented cobalt but from dissolution of intermediate Co(OH)2 and CoSO4 salts.
  • Decision support system for bioleaching processes
    • Abstract: Publication date: Available online 8 September 2018Source: HydrometallurgyAuthor(s): Cecilia Demergasso, Roberto Véliz, Pedro Galleguillos, Sabrina Marín, Mauricio Acosta, Víctor Zepeda, Jaqueline Zeballos, Felipe Henríquez, Rodrigo Pizarro, Juan Bekios-Calfa The use of information available in the organizations to understand what good performance looks like has been proposed for improving the decreased productivity in mine sector. Detailed monitoring has been performed at the heap bioleaching process in Minera Escondida since the start of the industrial operation in 2006. The huge industrial data recorded represents an opportunity to raise knowledge about complex bioleaching processes for improving the technology. A systematic approach using machine learning tools for the analysis of High Dimensional Feature Space is now being developed to deliver experience-based learning with the aim to serve as the foundation for optimal production planning and operational decision making, in the presence of inherent process variations. The construction of a Decision Support System (DSS) is reported, which considers a Real Time PCR array, a database for data logging and storage, the application of suitable statistical and computational tools for knowledge acquiring and finally the creation of a system of knowledge translation to transform it into action by applying recommendations that come to terms with operational limitations. The user can accurately retrieve data and design similar matches to the historic operation to get, for instance the expected metallurgical performance (such as copper recovery, acid consumption and bacterial activity) and recommendations. The process followed to construct the base of knowledge of the DSS is discussed.
  • Flow field characterization in the vicinity of vertical plane electrodes
           in a bench-scale zinc electrowinning cell
    • Abstract: Publication date: Available online 7 September 2018Source: HydrometallurgyAuthor(s): Jin Luo, PengPeng Jiao, Ning Duan, Fuyuan Xu, Linhua Jiang Characteristics of flow fields in the vicinity of vertical plane electrodes in a bench-scale zinc electrolysis cell were visualized using particle image velocimetry (PIV). Two experimental conditions, fN (current density = 0 A m−2) and fW (current density = 440 A m−2), were applied to investigate and compare the pump-induced and bubble-induced flows. The flow patterns in the selected region changed from vortex topology in fN to smooth streamlines in fW. In the presence of rising electrogenerated bubbles, the average velocity of the electrolyte between electrodes increased around 9 times. Based on the spatial velocity variation in fW, the average thicknesses of the bubble diffusion regions near the anode and the cathode were 3.59 mm and 3.78 mm, respectively, where the local turbulence was significantly stronger than that in the bulk region. It is noteworthy that near the anode surface, the turbulence intensity increased linearly (R = 0.99) upwards from the anode bottom, indicating that the local turbulent two-phase flow might be attributed to the accumulated perturbations from individual bubbles. The drag effect of the bubble curtains was the main driving force to renew the electrolyte within electrode gap rather than the electrolyte feeding into cell in the zinc electrowinning system.
  • Effect of temperature on the stability constants of zinc- nitrilotriacetic
           acid- ammonia system
    • Abstract: Publication date: Available online 7 September 2018Source: HydrometallurgyAuthor(s): Tianzu Yang, Boyi Xie, Lin Chen, Zhandong Hao, Duchao Zhang, Weifeng Liu To study the effect of temperature on the stability constant of zinc-nitrilotriacetic acid- ammonia (Zn-NTA-NH3) system, the protonation constants of the free ligands and stability constants of the ternary complexes were determined via pH potentiometric method at temperatures of 25.0 °C, 40.0 °C, 55.0 °C, 70.0 °C. The first and second stability constants of Zn-NTA-NH3 system decrease from 11.83, 14.00 to 10.72, 12.81, respectively, with the temperature increasing from 25.0 °C to 70.0 °C. While those of the Zn-NTA-H2O system decrease from 9.20, 11.98 to 8.27, 11.29. These results indicate that Zn-NTA-NH3 system is more stable than Zn-NTA-H2O system, leading to enhanced zinc leaching efficiency in the zinc leaching process.
  • Dissolution of calcium, phosphate, fluoride and rare earth elements (REEs)
           from a disc of natural fluorapatite mineral (FAP) in perchloric,
           hydrochloric, nitric, sulphuric and phosphoric acid solutions: A kinetic
           model and comparative batch leaching of major and minor elements from FAP
           and RE-FAP concentrate
    • Abstract: Publication date: Available online 6 September 2018Source: HydrometallurgyAuthor(s): A.M.T.S. Bandara, G. Senanayake Some rare earth phosphate minerals are associated with fluorapatite (FAP) in phosphate ores which make them a potential source of rare earth elements (REEs), to satisfy the increasing demand of REEs, especially for green energy technology and new energy materials. Previous studies have shown that the leachability of different elements which may be categorised as REEs and non-REEs in different acid solutions with the possibility of selective leaching of non-REEs by phosphoric acid to produce a REE rich leach residue which can be processed separately. This study investigates the dissolution of calcium, phosphate, fluoride and REEs from a rotating disc of a natural FAP mineral sample in perchloric, hydrochloric, nitric, sulphuric and phosphoric acid solutions under various leach conditions including different acid concentrations and temperatures and compares the results with batch leaching of natural FAP mineral and RE-FAP concentrate particles.The dissolution rate of REEs, which occur as minor elements in FAP mineral disc, are lower than that of the major elements: Ca, P and F. Higher dissolution rate of calcium from FAP disc in solutions of HCl, HNO3 and H2SO4 compared to HClO4 at high acid concentrations are due to the influence of Cl−, NO3− and SO42− ions, caused by association with Ca2+ ions in disc leaching, but precipitation of CaSO4 retard particle leaching in H2SO4. Despite the lower leaching rates of REEs due to low abundance of REEs on FAP mineral disc surface, the rates in 0.5 mol L−1 acid solutions follow the order H2SO4, HNO3 > HCl > HClO4 > H3PO4 indicating the beneficial effect of ion-association of the type RE(III)-sulfate/nitrate compared to RE(III)-phosphate precipitation. The higher leaching efficiencies of REEs in H3PO4 during first 10 min also decreases with prolonged leaching due to RE(III)-phosphate precipitation. The leaching efficiencies of Ca, Sr, Fe, Al and Mg are in the range 50–100% in 3.25 mol L−1 HCl, HNO3, HClO4 and H3PO4, compared to REEs, Th and U which vary in the range 20–80%, depending upon the formation of complex species or precipitation. A comparison between elemental composition of natural FAP mineral and a RE-FAP concentrate and their similarities in leaching behaviour in different acids is also presented highlighting the exceptional behaviour of phosphoric acid to selectively leach majority of non-REEs leaving REEs and silica in the leach residue.The surface reaction kinetic models and mechanisms are used to show that the dissolution reaction of calcium is mainly controlled by a chemical phenomenon in strong acids and phosphoric acid at the temperature range 25–50 °C. The experimental reaction orders with respect to H+ concentration in HCl, HNO3, HClO4, H2SO4 and H3PO4 in the range 0.46–0.93 for the dissolution reaction of calcium and/or phosphate are explained on the basis of stoichiometric dissolution and the influence of ion-association of anions with H+ and Ca2+.
  • A process to recover high purity iodine in wastewater from liquid crystal
           display (LCD) manufacturing industry
    • Abstract: Publication date: Available online 6 September 2018Source: HydrometallurgyAuthor(s): Hong In Kim, Janaka Jayamini Wijenayake, Debasish Mohapatra, Pradeep C. Rout The polarization process during LCD manufacturing generates wastewater containing significant amounts of valuable elements such as iodine and boron. The present paper outlines a process to recover iodine value from wastewater using oxidative precipitation followed by a solvent extraction (SX) technique. With H2O2 as an oxidant, 95% of iodine was precipitated out at a pH of 0.9 from a wastewater bearing 10.2 g/L of iodide and 0.82 g/L of boron. The remaining iodine, which could not be precipitated due to its low concentration, was recovered by SX using xylene as an organic solvent diluted in kerosene. Quantitative extraction and stripping were achieved using 0.05 M xylene and 0.1 M ascorbic acid at O:A ratios of 1:3 and 6:1, respectively. The purity rates of the iodine produced by the precipitation and SX routes were 99.3% and 99.8%, respectively. The highest separation factor achieved by the iodine‑boron system was 28,900 at an equilibrium pH value of 0.5. The present process is economically and environmentally friendly and therefore, can be used as an alternative industrial technique to recover iodine from wastewater.
  • Quantitative mineralogy and geochemistry of pelletized sulfide-bearing
           gold concentrates in an alkaline heap leach
    • Abstract: Publication date: Available online 6 September 2018Source: HydrometallurgyAuthor(s): Elizabeth A. Holley, Yu Ting Yu, Alexis Navarre-Sitchler, Jeffrey Winterton Sulfide-rich gold mill concentrates from the Cripple Creek & Victor Gold Mining Co. (CC&V) in Colorado, USA were pelletized with Portland cement at 20, 80 or 200 lbs./ton. The hand-formed ~1 in. diameter pellets were leached in a bench-scale heap leach system for 16 weeks in a 0.3 mM NaOH solution at pH 10.5, in a matrix of crushed ore or clear acrylic balls. Leached pellets were sampled every two weeks. The sampled pellets were encapsulated in epoxy, cut, polished, and examined using a field emission scanning electron microscope equipped with an automated mineralogy system. Leachate samples were collected after 2, 4, 6, 8 and 16 weeks and analyzed for major cations. Higher cement concentrations produced pellets with better macroscopic integrity, although microscopically and chemically detectable degradation occurred at all cement concentrations tested. Pellets with 200 lbs./ton cement retained their physical integrity macroscopically throughout the trial, whereas pellets with 20 and 80 lbs./ton cement were significantly fractured within 2 days of leaching. Mineralogical analyses by electron microscopy showed that physical degradation was localized where cement had been removed. The electron microscopy also revealed that all pellets had cement-leached rims by 8 weeks, and sulfide:oxide ratios decreased in most experiments. Leachate concentrations of Ca, Ba and Sr were initially high and decreased over the experiment, consistent with rapid dissolution of cement from the pellets in the first 4 weeks. These results show that pellets will break apart and dissolve on the heap leach pad at all of the tested binder concentrations; thus pelletizing CC&V mill concentrates is not likely to improve leach pad permeability or minimize acid generation. The combination of automated mineralogy, element mapping, and chemical analysis of leachates proved to be an effective means of monitoring leach behavior of fine-grained materials. The Ca element mapping was the most efficient method of monitoring cement binder degradation.
  • Effect of mechanical activation on the leaching kinetics of
           niobium-bearing mineralisation in KOH hydrothermal system
    • Abstract: Publication date: Available online 5 September 2018Source: HydrometallurgyAuthor(s): Xiaohui Wang, Yujuan Jia, Shuhua Ma, Shili Zheng, Qing Sun The leaching kinetics of niobium-bearing mineralisation in KOH hydrothermal system was investigated. Particle size analyzer, XRD and SEM were used for studying the influences of mechanical activation on particle size, surface area, crystal structure and surface morphology of niobium-bearing mineralisation. The results showed that mechanical activation decreased the mineral particle size, increased the surface area and the degree of lattice distortion or disorder. Kinetics of alkali leaching of niobium is modeled and explained. The activation energy of niobium leaching from unactivated niobium-bearing mineralisation was 45.6 kJ/mol. When the mineralisation was activated for 10 min and 30 min, the activation energy decreased to 32.2 kJ/mol and 21.9 kJ/mol respectively. Compared with the non-mechanical activation method, mechanical activation greatly improved the activity of niobium-bearing mineralisation and decreased the activation energy, so that the reaction speed was accelerated remarkably.
  • Regeneration of alkali leaching solution through precipitation using
           calcium hydroxide
    • Abstract: Publication date: Available online 31 August 2018Source: HydrometallurgyAuthor(s): Richard Machiela, Long Zhang, Mingming Zhang, Timothy Eisele Sodium hydroxide (NaOH) is known to be capable of selectively leaching phosphorus from oolitic iron ores. The main limitation on implementing this leaching approach is the expense of NaOH. In order to make sodium hydroxide leaching practical, a method is needed for removing the dissolved phosphorus from solution and inexpensively regenerating the sodium hydroxide. In this work, removal of phosphorus from solution was achieved using calcium hydroxide (Ca(OH)2), which is significantly less expensive than NaOH. The addition of Francolite seed crystals greatly accelerates the precipitation rate. Up to 99.9% of phosphorus in solution was removed within thirty minutes. A leaching comparison between fresh and regenerated caustic solution was performed, with removal rates of 51.9% and 52.2% respectively, demonstrating that the regenerated leaching solution was still effective for removing phosphorus.
  • Mechanism of poisoning hydroxyoximes by cobalt in different organic
    • Abstract: Publication date: Available online 31 August 2018Source: HydrometallurgyAuthor(s): Qi Sun, Limei Yang, Songtao Huang, Zheng Xu, Yan Li, Wei Wang Poisoning of 2-hydroxy-5-nonylbenzaldoxime (Mextral 84H) by cobalt in the presence of neodecanoic acid (Versatic 10) and bis(2-ethylhexyl) phosphoric acid (P204) diluted in aliphatics was comparatively studied. The cobalt-organic extractants species structure and stoichiometry were determined by slope analysis, Fourier transform infrared (FT-IR) spectrometer, visible absorption and cyclic voltammetry. It is found that P204 can significantly inhibit the poisoning of Mextral 84H by cobalt and the poisoning is weakened with the increase of P204 concentration while Versatic 10 has no effect on it. The stoichiometries of adducts formed in the organic phase with Mextral 84H (HL) in the presence of Versatic 10 and P204 (HA) are CoL2 · 2H2O and Co(H2A2L2), respectively. The divalent cobalt in the CoL2 · 2H2O complex is easily oxidized to trivalent cobalt because of its inner-orbital d2sp3 hybridization, resulting in low oxidation potential and the poisoning of Mextral 84H by cobalt in the presence of oxygen. With the addition of P204, the hybridization configuration of the cobalt complex transforms from d2sp3 to the more stable sp3d2, and the oxidation potential of divalent cobalt in the organic phase significantly increases to prevent the Co(H2A2L2) complex from being oxidized, resulting in the significantly inhabitation of the poisoning Mextral 84H by cobalt in the presence of oxygen.Graphical abstractUnlabelled Image
  • Mechanochemical pre-treatment of lateritic nickel ore with sulfur followed
           by atmospheric leaching
    • Abstract: Publication date: Available online 31 August 2018Source: HydrometallurgyAuthor(s): Huseyin Basturkcu, Marcela Achimovičová, Mária Kaňuchová, Neset Acarkan In this study, the role of mechanochemical pre-treatment with the addition of S in atmospheric agitation leaching of a lateritic nickel ore was investigated. In the mechanically activated sample with S (20 wt%), the amount of Ni-Co-bearing amorphous FeMg hydrosilicate phases decreased and a new FeMgS phase was formed. In addition, the formation of NiSO4 was determined by X-ray photoelectron spectroscopy analysis. The effect of leaching temperature, leaching time, H2SO4 concentration, and the amount of S added during the mechanochemical pre-treatment on the extractability of Ni, Fe, and Co were investigated. When the mechanically activated sample with 20% added S was leached for 2 h under conditions of a solid/liquid ratio of 1/2.5 (w/w), temperature of 85 °C, and H2SO4 concentration of 300 g/L, 92.0% Ni, 79.1% Fe, and 84.8% Co extractions were achieved. Moreover, 17.5% lower Ni extraction was obtained using the mechanically activated sample without S. In terms of leaching behavior, the relationship between Ni and Fe dissolution weakened after mechanochemical activation. Furthermore, the leaching of the newly formed compounds was mostly controlled by the chemical reaction model.
  • Simultaneous removal of sulfur and iron by the seed precipitation of
           digestion solution for high-sulfur bauxite
    • Abstract: Publication date: Available online 28 August 2018Source: HydrometallurgyAuthor(s): Xuejiao Zhou, Jianguo Yin, Yongli Chen, Wentang Xia, Xiaoyan Xiang, Xiaoli Yuan Sulfur in bauxite ore results in a series of notable negative effects in Bayer process. It is necessary to remove sulfur for the utilization of high-sulfur bauxite resources. A novel process involving seed precipitation of digestion solution was adopted to simultaneously remove sulfur and iron from the sodium aluminate solution for the high-sulfur bauxite. Seed was prepared from the digestion solution of pyrite in a water bath. X-ray diffraction, a scanning electron microscope and chemical analysis were used to characterize the prepared seed. The utilization of the seed precipitation to remove sulfur and iron for the sulfur-containing sodium aluminate solution was studied. The various parameters included seed dosage, agitation speed and temperature. The results indicated that seed dosage and temperature had a remarkable effect on the sulfur and iron removal. Under the optimum condition, the removal percentages of sulfur and iron from the digestion solution can achieve to 76% and 87%, respectively, and the loss of alumina is lower than 2%. The research shows that the sulfur and iron seed prepared from pyrite can be used effectively for the sulfur and iron removal. A cyclic flowsheet for the simultaneous removal of sulfur and iron for high-sulfur bauxite is proposed.
  • Microbial recovery of gold from neutral and acidic solutions by the
           baker's yeast Saccharomyces cerevisiae
    • Abstract: Publication date: Available online 28 August 2018Source: HydrometallurgyAuthor(s): Norizoh Saitoh, Ryotaro Fujimori, Masaki Nakatani, Daijiro Yoshihara, Toshiyuki Nomura, Yasuhiro Konishi An environmentally friendly method using the baker's yeast Saccharomyces cerevisiae was developed to recover soluble Au(III) from neutral and acidic solutions at room temperature. Resting cells of S. cerevisiae were able to reduce aqueous Au(III) ions in HAuCl4 solution to metallic Au(0) at pH 7.0 within 120 min when formate was provided as the electron donor under anaerobic conditions. Gold nanoparticles were deposited on the cell surface of S. cerevisiae. The S. cerevisiae cells were also applicable to a bio-material for adsorbing aqueous Au(III) ions from HAuCl4 solution at pH 1.0 under air atmosphere. When processing the aqua regia leachate of electronic waste (Central Processing Units, CPU), the S. cerevisiae cells were able to rapidly and selectively collect aqueous Au(III) ions from the aqua regia leachate at pH 1.2 within 10 min. Our proposed microbial methods enable the rapid and efficient recovery of gold over the pH range 1.0 to 7.0.
  • Prediction of holdup and drop size distribution in a disc-doughnut pulsed
           column with tenova kinetics internals for the water-Alamine 336 system
    • Abstract: Publication date: Available online 27 August 2018Source: HydrometallurgyAuthor(s): Wen Li, Yong Wang, Kathryn A. Mumford, Kathryn H. Smith, Geoffrey W. Stevens Tenova Pulsed Column Kinetics Internals (TPC-KIs) are a newly designed type of pulsed column internals with a novel structure that is expected to achieve less back-mixing, higher holdup and improved mass transfer. This study compared the hydrodynamic performance of TPC-KIs with standard disc and doughnut internals in a 2 m high 76 mm diameter pulsed solvent extraction column with the water-Alamine 336-Shellsol 2046 system. The effects of the wettability of column internals have also been considered. Dispersed phase holdup and Sauter mean droplet diameter were measured under various pulsation intensity and velocities of both phases, and empirical correlations for holdup and drop size have been refitted within absolute average relative errors within 15%. Tenova kinetics internals has lower holdup and larger Sauter-mean drop size compared to standard disc and doughnut internals, and these hydrodynamic parameters are predictable using the developed correlation in this study.
  • Selective extraction and recovery of copper from chloride solution using
           Cextrant 230
    • Abstract: Publication date: Available online 27 August 2018Source: HydrometallurgyAuthor(s): Yongjiao Wang, Zhifeng Zhang, Shengting Kuang, Guolong Wu, Yanling Li, Yunhui Li, Wuping Liao The extraction behavior of Cu(II) from chloride solution was investigated using di(2-ethylhexyl) [N-(2-ethylhexyl)aminomethyl] phosphonate (Cextrant 230, L). Cextrant 230 has a higher selectivity for Cu(II) over other divalent metal ions, e.g. Co(II), Ni(II), Mg(II) and Ca(II). The effect of the concentration of chloride ion and the extractant, aqueous pH values and temperature on the Cu(II) extraction was studied in detail. A possible extraction mechanism was proposed and the extracted complex was determined to be CuCl2·3L by the slope analysis method. Thermodynamic parameters (ΔG, ΔH and ΔS) were calculated, suggesting that the copper extraction was an exothermic process. The loading capacity of 30% (v/v) Cextrant 230 was 16.9 g Cu/L. The loaded Cu(II) can be stripped efficiently by HCl, HNO3 and H2SO4. A extraction process for the selective extraction and recovery of Cu(II) from a raffinate obtained after the recovery of rare earths from the waste NdFeB magnets was proposed, by which the purity of copper product reached 99.5% with a yield of 98.0%.
  • Bioleaching of arsenopyrite from Janggun mine tailings (South Korea) using
           an adapted mixed mesophilic culture
    • Abstract: Publication date: Available online 23 August 2018Source: HydrometallurgyAuthor(s): Emmanuel Ngoma, Danilo Borja, Mariette Smart, Kathija Shaik, Hyunjung Kim, Jochen Petersen, Susan T.L. Harrison This article explores a heap bioleaching technology for the removal of arsenic (As) from mine tailings using the GEOCOAT™ technique. Small-scale columns were operated at fixed temperatures of 20 °C, 30 °C, and 45 °C and at ramped-up temperatures from 25 °C to 45 °C using a mixed mesophilic acidophilic iron and sulfur oxidizing microbial culture, adapted to high As concentration (20 g/L). The packed-bed columns were filled with inert granite pebbles coated with Janggun Mine tailings, irrigated with a 1 g/L ferrous-enriched 0 K medium and aerated with 200 mL/min compressed air. To study the microbial colonization at various stages of the leaching process relative to the initial inoculum, the ramped-up-temperature experiment was conducted in triplicate and the columns were sacrificed after different leaching periods. The fixed-temperature column samples were sampled upon the termination of each experiment, for microbial speciation of the culture attached to the mineral during the leaching of the ore. The As that was released into the solution, the iron oxidation rates, the pH and the redox potential were used to assess the leaching performance of each column. A triangulation of the results between the fixed and the ramped-up temperatures allowed determination of the influence of temperature on As leaching kinetics and microbial distribution. 94–97% As removal was achieved among the various column experiments, 88 days after inoculation. The results showed that increased temperature induced an increased lag in the As leaching phase. Temperature also affected the abundance of acidophilic microorganisms present in the combined bulk volume of the column and on the mine tailings. The mesophilic bacterial species Acidithiobacillus caldus and Leptospirillum ferriphilum were the dominant biooxidation species (> 60%) in both the inoculum applied to the columns and in Col. A operated at a fixed 20 °C. Increased incubation temperature resulted in a decrease in the number of bacterial cells; however, the number of archaeal cells remained similar with a resulting increase in the archaeal dominance at 45 °C. The ramped-up temperature study showed similar results with an increase in both cell numbers and archaeal dominance between day 42 and 84. Overall, this study demonstrated the feasibility of As detoxification from the Janggun Mine tailings using microbial heap leaching.
  • A clean metallurgical process for separation and recovery of vanadium and
           chromium from V-Cr-bearing reducing slag
    • Abstract: Publication date: Available online 23 August 2018Source: HydrometallurgyAuthor(s): Xuewen Wang, Daxiong Gao, Bianfang Chen, Yuqi Meng, Zibi Fu, Mingyu Wang In this work, a clean metallurgical process is used to separate and recover vanadium and chromium from V-Cr-bearing reducing slag. Comparing with the traditional process, the process not only reduces the use of sulfuric acid, but also saves the cost of wastewater purification. The process consists of four procedures: low temperature sulphating roasting, reduction leaching, selectively oxidizing and the oxides of vanadium and chromium preparing. Among these, the reduction leaching and selectively oxidizing are the key steps. Low temperature sulphating roasting is used to strengthen the decomposition of V-Cr-bearing reducing slag, Na2SO3 is used for the reduction of vanadium from V(V) to V(IV) or V(III), CrO3 is used to selectively oxidize the vanadium in the leached solution, (NH4)2SO4 is used to make the vanadium precipitated in the form of ammonium polyvanadate, and NaOH is used to precipitate Cr(III) from the V precipitated solution. It was found that the leaching efficiencies of Cr and V can reach 99.7% and 99.6% respectively by low temperature sulphating roasting and reduction leaching. The products of V2O5 with purity 99.1% and Cr2O3 with purity 98.9% were obtained by treating the ammonium polyvanadate and the precipitate of Cr(III), respectively.
  • Recovery of scandium from sulfuric acid solution with a macro porous
           TRPO/SiO2-P adsorbent
    • Abstract: Publication date: Available online 31 July 2018Source: HydrometallurgyAuthor(s): Qing Yu, Shunyan Ning, Wei Zhang, Xinpeng Wang, Yuezhou Wei A macro porous silica-polymer based TRPO/SiO2-P adsorbent was prepared for recovery of scandium from sulfuric acid solution. The as-prepared TRPO/SiO2-P was characterized by SEM-EDS, TG-DSC, BET, IR. It was found the adsorption of TRPO/SiO2-P towards Sc reached equilibrium in 120 min with the saturated adsorption amount about 13.3 mg/g. It needed about six molecules of TRPO/SiO2-P to uptake 2 molecules of Sc(III), meanwhile three molecules of SO42− were needed for charge balance. Furthermore, TRPO/SiO2-P exhibited high adsorption selectivity towards Sc and almost no adsorption towards the other RE and Al, Fe and little adsorption towards Ti which could be effectively suppressed by H2O2. And column experiments showed clear separation of Sc from Al, Ti, Fe, Y, La and Ce in the effluent, indicating TRPO/SiO2-P could successfully separate Sc from the other metal ions. In a word, TRPO/SiO2-P is a very promising adsorbent for Sc separation from the H2SO4 system.Graphical abstractUnlabelled Image
  • Effect of iron(II) and manganese(II) on oxidation and co-precipitation of
           cobalt(II) in ammonia/ammonium carbonate solutions during aeration - An
           update and insight to cobalt losses in the Caron process for laterite ores
    • Abstract: Publication date: Available online 20 July 2018Source: HydrometallurgyAuthor(s): Graeme Thompson, Gamini Senanayake The Caron process involves the roasting of nickel laterite ore at 750 °C with fuel oil to produce a calcine containing Fe-Ni-Co alloy and other reacted or unreacted host minerals. The leaching of the calcine in the form of a quenched slurry in ammonia/ammonium carbonate solutions at pH ~10 and 45 °C under anaerobic and aerobic conditions sequentially dissolves alloy to iron(II), nickel(II) and cobalt(II), oxidizes iron(II), precipitates iron(III) and allows the discard of iron rich tailings after counter current decantation and steam stripping of ammonia and carbon dioxide for recycling. Oxidation of aqueous cobalt(II) during aeration in the Caron Process is one of the critical steps to reduce the incorporation of cobalt into the tailings. Cobalt(II) species which are co-precipitated with the iron phase are not able to be leached back into solution and lost to the tailings, but cobalt(III) remains in solution. Fast oxidation of cobalt(II) to cobalt(III) is expected to minimise the co-precipitation of cobalt(II) during iron precipitation, resulting in smaller losses of cobalt to tailings. Results from this study show that the oxidation of cobalt(II) species (1 g L−1) in a synthetic ammonium carbonate (SAC) solution containing 5.3 M NH3/NH4+(total) and 1.5 M HCO3– is relatively slow at room temperature and follows first order kinetics with respect to cobalt(II) concentration. The rate of reaction is temperature dependent with an activation energy of 65.8 kJ mol−1. The presence of manganese(II) and iron(II) increases the rate of oxidation of cobalt(II) when compared to that of cobalt(II) alone. The oxidation of cobalt(II) occurs only after most of iron(II) is oxidised to iron(III) solids which facilitates the co-precipitation of cobalt(II). The variation of the concentration of manganese(II) (0.025–1.25 g L−1) in SAC solution demonstrates minimal effect on cobalt oxidation. Analysis of the solids, using XRD, show that the final solid formed in the laboratory test by the aeration of iron(II) in SAC solution consisted of goethite and ferrihydrite and that formed by the aeration of manganese(II) in SAC solution was rhodochrosite (MnCO3). While the iron oxide precipitated during the oxidation of Fe(II) + Co(II) for 1 h in the laboratory test contains 0.38% Co, the solids formed in aerated tanks in the Caron processing plant increases from 0.15% in Tank 1 to 0.17% in Tank 4, but in all cases too low to be detected in XRD scans.
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