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Metals, Volume 5, Issue 3 (September 2015), Pages 1127-1769

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Open AccessArticle Experimental Study of the Mg-Ni-Y System at 673 K Using Diffusion Couples and Key Alloys
Metals 2015, 5(3), 1746-1769; https://doi.org/10.3390/met5031746
Received: 1 September 2015 / Revised: 15 September 2015 / Accepted: 16 September 2015 / Published: 22 September 2015
Cited by 6 | PDF Full-text (2338 KB) | HTML Full-text | XML Full-text
Abstract
Three solid-solid and two solid-liquid diffusion couples together with 32 key samples were used to construct the isothermal section of the Mg-Ni-Y system at 673 K. The present investigation revealed 12 ternary intermetallic compounds. Crystal structures of two ternary compounds τ1 (Gd
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Three solid-solid and two solid-liquid diffusion couples together with 32 key samples were used to construct the isothermal section of the Mg-Ni-Y system at 673 K. The present investigation revealed 12 ternary intermetallic compounds. Crystal structures of two ternary compounds τ1 (Gd4RhIn prototype with lattice parameter of a = 1.3666 nm) and τ2 (Mo2FeB2 prototype with lattice parameters of a = 0.7395 nm and c = 0.3736 nm) were determined. The phase relations and ternary solubility of the binary and ternary compounds at 673 K were determined using scanning electron microscopy (SEM), wave dispersive X-ray spectrometer (WDS) and X-ray diffraction (XRD) analysis. Full article
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Open AccessArticle Low-Temperature Mechanical Behavior of Super Duplex Stainless Steel with Sigma Precipitation
Metals 2015, 5(3), 1732-1745; https://doi.org/10.3390/met5031732
Received: 13 July 2015 / Revised: 31 August 2015 / Accepted: 15 September 2015 / Published: 18 September 2015
Cited by 4 | PDF Full-text (1350 KB) | HTML Full-text | XML Full-text
Abstract
Experimental studies in various aspects have to be conducted to maintain stable applications of super duplex stainless steels (SDSS) because the occurrence rate of sigma phase, variable temperature and growth direction of sigma phase can influence mechanical performances of SDSS. Tensile tests of
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Experimental studies in various aspects have to be conducted to maintain stable applications of super duplex stainless steels (SDSS) because the occurrence rate of sigma phase, variable temperature and growth direction of sigma phase can influence mechanical performances of SDSS. Tensile tests of precipitated SDSS were performed under various temperatures to analyze mechanical and morphological behavior. Full article
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Open AccessArticle Constitutive Relationship Modeling and Characterization of Flow Behavior under Hot Working for Fe–Cr–Ni–W–Cu–Co Super-Austenitic Stainless Steel
Metals 2015, 5(3), 1717-1731; https://doi.org/10.3390/met5031717
Received: 4 August 2015 / Revised: 9 September 2015 / Accepted: 15 September 2015 / Published: 18 September 2015
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Abstract
The hot deformation behavior of a Fe–22Cr–25Ni–3.5W–3Cu–1.5Co super-austenitic stainless steel was investigated using isothermal compression tests with a wide range of temperatures (1173–1373 K) and strain rates (0.1–10 s−1). The results showed that all the flow curves gradually turned to balanced stress state
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The hot deformation behavior of a Fe–22Cr–25Ni–3.5W–3Cu–1.5Co super-austenitic stainless steel was investigated using isothermal compression tests with a wide range of temperatures (1173–1373 K) and strain rates (0.1–10 s−1). The results showed that all the flow curves gradually turned to balanced stress state without notable peak stress characteristics during the entire deformation, which indicated that the dynamic recovery behavior played a main restoration mechanism in the steel. Modeling constitutive equations relating to the temperature, strain rate and flow stress were proposed to determine the materials constants and activation energy necessary for deformation. In order to give the precise predicted values of the flow behavior, the influence of strain was identified using polynomial functions. The relationship of flow stress, temperature and strain rate was represented by the Zener-Hollomon parameter including the Arrhenius term. The predicted results validated that the developed constitutive equations can describe high temperature flow behavior well. Furthermore, a modified Zener-Hollomon parameter map of the studied steel was developed to clarify the restoration mechanism based on the constitutive modeling data and microstructural observation. Full article
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Open AccessArticle Characterization of Microstructure and Mechanical Properties of Resistance Spot Welded DP600 Steel
Metals 2015, 5(3), 1704-1716; https://doi.org/10.3390/met5031704
Received: 9 July 2015 / Revised: 10 September 2015 / Accepted: 13 September 2015 / Published: 17 September 2015
Cited by 12 | PDF Full-text (1712 KB) | HTML Full-text | XML Full-text
Abstract
Resistance spot welding (RSW) as a predominant welding technique used for joining steels in automotive applications needs to be studied carefully in order to improve the mechanical properties of the spot welds. The objectives of the present work are to characterize the resistance
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Resistance spot welding (RSW) as a predominant welding technique used for joining steels in automotive applications needs to be studied carefully in order to improve the mechanical properties of the spot welds. The objectives of the present work are to characterize the resistance spot weldment of DP600 sheet steels. The mechanical properties of the welded joints were evaluated using tensile-shear and cross-tensile tests. The time-temperature evolution during the welding cycle was measured. The microstructures observed in different sites of the welds were correlated to thermal history recorded by thermocouples in the corresponding areas. It was found that cracks initiated in the periphery region of weld nuggets with a martensitic microstructure and a pull-out failure mode was observed. It was also concluded that tempering during RSW was the main reason for hardness decrease in HAZ. Full article
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Open AccessArticle Effect of Post Heat Treatment on the Microstructure and Microhardness of Friction Stir Processed NiAl Bronze (NAB) Alloy
Metals 2015, 5(3), 1695-1703; https://doi.org/10.3390/met5031695
Received: 20 July 2015 / Revised: 21 August 2015 / Accepted: 24 August 2015 / Published: 16 September 2015
Cited by 6 | PDF Full-text (1707 KB) | HTML Full-text | XML Full-text
Abstract
NiAl bronze (NAB) alloy is prepared by using friction stir processing (FSP) technique at a tool rotation rate of 1200 rpm and a traverse speed of 150 mm/min. A post heat treatment is performed at the temperature of 675 °C. The effect of
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NiAl bronze (NAB) alloy is prepared by using friction stir processing (FSP) technique at a tool rotation rate of 1200 rpm and a traverse speed of 150 mm/min. A post heat treatment is performed at the temperature of 675 °C. The effect of heat treatment on the microstructure and microhardness is studied. The results show that the microstructure of the FSP NAB alloy consists of high density dislocations, retained β phase (β′ phase) and recrystallized grains. When annealed at 675 °C, discontinuous static recrystallization (DSRX) takes place. The content of β′ phase gradually decreases and fine κ phase is precipitated. After annealing for 2 h, both the microhardness of the FSP sample in the stir zone (SZ) and the difference in hardness between the SZ and base metal decrease due to the reduction of the dislocation density and β′ phase, accompanying recrystallized grain coarsening. With further increasing of the annealing time to 4 h, the aforementioned difference in hardness nearly disappears. Full article
(This article belongs to the Special Issue Casting Alloy Design and Modification)
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Open AccessArticle Mechanical Properties of Nanoporous Au: From Empirical Evidence to Phenomenological Modeling
Metals 2015, 5(3), 1665-1694; https://doi.org/10.3390/met5031665
Received: 30 June 2015 / Revised: 5 September 2015 / Accepted: 8 September 2015 / Published: 16 September 2015
Cited by 4 | PDF Full-text (1754 KB) | HTML Full-text | XML Full-text
Abstract
The present work focuses on the development of a theoretical model aimed at relating the mechanical properties of nanoporous metals to the bending response of thick ligaments. The model describes the structure of nanoporous metal foams in terms of an idealized regular lattice
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The present work focuses on the development of a theoretical model aimed at relating the mechanical properties of nanoporous metals to the bending response of thick ligaments. The model describes the structure of nanoporous metal foams in terms of an idealized regular lattice of massive cubic nodes and thick ligaments with square cross-sections. Following a general introduction to the subject, model predictions are compared with Young’s modulus and the yield strength of nanoporous Au foams determined experimentally and available in literature. It is shown that the model provides a quantitative description of the elastic and plastic deformation behavior of nanoporous metals, reproducing to a satisfactory extent the experimental Young’s modulus and yield strength values of nanoporous Au. Full article
(This article belongs to the Special Issue Nanoporous Metallic Alloys)
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Open AccessArticle Beeswax-Colophony Blend: A Novel Green Organic Coating for Protection of Steel Drinking Water Storage Tanks
Metals 2015, 5(3), 1645-1664; https://doi.org/10.3390/met5031645
Received: 30 July 2015 / Revised: 7 September 2015 / Accepted: 9 September 2015 / Published: 15 September 2015
Cited by 4 | PDF Full-text (1749 KB) | HTML Full-text | XML Full-text
Abstract
Beeswax-colophony blend is mainly used as a sealant mixture for preservation applications. The beeswax itself, however, has had a long way in history taking part in conservation processes including mummification. In this research, this blend was used as a protective coating for drinking
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Beeswax-colophony blend is mainly used as a sealant mixture for preservation applications. The beeswax itself, however, has had a long way in history taking part in conservation processes including mummification. In this research, this blend was used as a protective coating for drinking water distribution tanks. Initially, a layer with 400 μm thickness was applied on a sand blasted mild steel plate. The long-term electrochemical behavior of the coating was investigated by open circuit potential (OCP) and electrochemical microbiological characteristics of the coating, microbial and chemical examinations were performed on drinking water samples that had been in contact with the coating. Furthermore, its behavior in an up-flow anaerobic sludge blanket reactor (UASBR) in a wastewater treatment plant was investigated using the scanning electron microscopy (SEM) technique. Regarding the consistency of experimental results, it was concluded that this proposed recyclable blend could be considered as a novel green organic coating and also a good corrosion barrier even in aggressive environments. Full article
(This article belongs to the Special Issue Oxidation of Metals)
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Open AccessArticle Nickel Extraction from Olivine: Effect of Carbonation Pre-Treatment
Metals 2015, 5(3), 1620-1644; https://doi.org/10.3390/met5031620
Received: 19 August 2015 / Revised: 2 September 2015 / Accepted: 6 September 2015 / Published: 11 September 2015
Cited by 7 | PDF Full-text (1483 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this work, we explore a novel mineral processing approach using carbon dioxide to promote mineral alterations that lead to improved extractability of nickel from olivine ((Mg,Fe)2SiO4). The precept is that by altering the morphology and the mineralogy of
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In this work, we explore a novel mineral processing approach using carbon dioxide to promote mineral alterations that lead to improved extractability of nickel from olivine ((Mg,Fe)2SiO4). The precept is that by altering the morphology and the mineralogy of the ore via mineral carbonation, the comminution requirements and the acid consumption during hydrometallurgical processing can be reduced. Furthermore, carbonation pre-treatment can lead to mineral liberation and concentration of metals in physically separable phases. In a first processing step, olivine is fully carbonated at high CO2 partial pressures (35 bar) and optimal temperature (200 °C) with the addition of pH buffering agents. This leads to a powdery product containing high carbonate content. The main products of the carbonation reaction include quasi-amorphous colloidal silica, chromium-rich metallic particles, and ferro-magnesite ((Mg1−x,Fex)CO3). Carbonated olivine was subsequently leached using an array of inorganic and organic acids to test their leaching efficiency. Compared to leaching from untreated olivine, the percentage of nickel extracted from carbonated olivine by acid leaching was significantly increased. It is anticipated that the mineral carbonation pre-treatment approach may also be applicable to other ultrabasic and lateritic ores. Full article
(This article belongs to the Special Issue Hydrometallurgy) Printed Edition available
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Open AccessArticle Exploring the Possibilities of Biological Fabrication of Gold Nanostructures Using Orange Peel Extract
Metals 2015, 5(3), 1609-1619; https://doi.org/10.3390/met5031609
Received: 22 July 2015 / Revised: 3 September 2015 / Accepted: 6 September 2015 / Published: 11 September 2015
Cited by 4 | PDF Full-text (908 KB) | HTML Full-text | XML Full-text
Abstract
Development of nanotechnology requires a constant innovation and improvement in many materials. The exploration of natural resources is a promising eco-friendly alternative for physical and chemical methods. In the present work, colloidal gold nanostructures were prepared using orange peel extract as a stabilizing
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Development of nanotechnology requires a constant innovation and improvement in many materials. The exploration of natural resources is a promising eco-friendly alternative for physical and chemical methods. In the present work, colloidal gold nanostructures were prepared using orange peel extract as a stabilizing and reducing agent. The initial pH value of the solution and the concentration of the gold precursor had an effect on the formation and morphology of nanoparticles. The method developed is environmentally friendly and allows control of nanoparticles. By controlling the pH and, especially, the gold concentration, we are able to synthesize crystalline gold nanowires using orange peel extract in the absence of a surfactant or polymer to direct nanoparticle growth, and without external seeding. UV-VIS spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize the nanoparticles obtained by biosynthesis. Full article
(This article belongs to the Special Issue Hydrometallurgy) Printed Edition available
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Open AccessArticle Heavy Metal Behavior in Lichen-Mine Waste Interactions at an Abandoned Mine Site in Southwest Japan
Metals 2015, 5(3), 1591-1608; https://doi.org/10.3390/met5031591
Received: 13 July 2015 / Revised: 26 August 2015 / Accepted: 28 August 2015 / Published: 2 September 2015
Cited by 3 | PDF Full-text (1324 KB) | HTML Full-text | XML Full-text
Abstract
The lichen, Stereocaulon exutum Nylander, occurring in a contaminated abandoned mine site was investigated to clarify (1) the behavior of heavy metals and As during the slag weathering processes mediated by the lichen; and (2) the distribution of these elements in the lichen
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The lichen, Stereocaulon exutum Nylander, occurring in a contaminated abandoned mine site was investigated to clarify (1) the behavior of heavy metals and As during the slag weathering processes mediated by the lichen; and (2) the distribution of these elements in the lichen thallus on slag. The heavy metals and As in the slag are dissolved from their original phases during the weathering process by lichen substances (organic acids) and hypha penetration, in addition to non-biological weathering. The dissolved elements are absorbed into the lichen thallus. Some of these dissolved elements are distributed in the cells of the hyphae. The others are distributed on the surface of the hyphae as formless particles and show lateral distribution inside the cortex of the thallus. The Cu and Zn concentrations in the thalli are positively correlated with the concentrations in the corresponding substrata and a positive intercept in the regression curve obtained using a linear function. These chemical characteristics make this lichen a good biomarker for Cu and Zn contamination of the substrata of the lichen. Therefore, the present study supposes that Stereocaulon exutum has a possible practical application in biomonitoring or risk assessment of heavy metal pollution at abandoned mine sites. Full article
(This article belongs to the Special Issue Hydrometallurgy) Printed Edition available
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Open AccessArticle Experimental and Numerical Studies on Self-Propagating High-Temperature Synthesis of Ta5Si3 Intermetallics
Metals 2015, 5(3), 1580-1590; https://doi.org/10.3390/met5031580
Received: 11 August 2015 / Revised: 21 August 2015 / Accepted: 28 August 2015 / Published: 1 September 2015
Cited by 5 | PDF Full-text (1008 KB) | HTML Full-text | XML Full-text
Abstract
Formation of Ta5Si3 by self-propagating high-temperature synthesis (SHS) from elemental powder compacts of Ta:Si = 5:3 was experimentally and numerically studied. Experimental evidence showed that the increase of either sample density or preheating temperature led to the increase of combustion
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Formation of Ta5Si3 by self-propagating high-temperature synthesis (SHS) from elemental powder compacts of Ta:Si = 5:3 was experimentally and numerically studied. Experimental evidence showed that the increase of either sample density or preheating temperature led to the increase of combustion wave velocity and reaction temperature. The apparent activation energy, Ea ≈ 108 kJ/mol, was determined for the synthesis reaction. Based upon numerical simulation, the Arrhenius factor of the rate function, K0 = 2.5 × 107 s−1, was obtained for the 5Ta + 3Si combustion system. In addition, the influence of sample density on combustion wave kinetics was correlated with the effective thermal conductivity (keff) of the powder compact. By adopting 0.005 ≤ keff/kbulk ≤ 0.016 in the computation model, the calculated combustion velocity and temperature were in good agreement with experimental data of the samples with compaction densities between 35% and 45% theoretical maximum density (TMD). Full article
(This article belongs to the Special Issue Intermetallics 2016) Printed Edition available
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Open AccessArticle Chalcopyrite Dissolution at 650 mV and 750 mV in the Presence of Pyrite
Metals 2015, 5(3), 1566-1579; https://doi.org/10.3390/met5031566
Received: 6 August 2015 / Revised: 21 August 2015 / Accepted: 25 August 2015 / Published: 28 August 2015
Cited by 1 | PDF Full-text (721 KB) | HTML Full-text | XML Full-text
Abstract
The dissolution of chalcopyrite in association with pyrite in mine waste results in the severe environmental issue of acid and metalliferous drainage (AMD). To better understand chalcopyrite dissolution, and the impact of chalcopyrite’s galvanic interaction with pyrite, chalcopyrite dissolution has been examined at
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The dissolution of chalcopyrite in association with pyrite in mine waste results in the severe environmental issue of acid and metalliferous drainage (AMD). To better understand chalcopyrite dissolution, and the impact of chalcopyrite’s galvanic interaction with pyrite, chalcopyrite dissolution has been examined at 75 °C, pH 1.0, in the presence of quartz (as an inert mineral) and pyrite. The presence of pyrite increased the chalcopyrite dissolution rate by more than five times at Eh of 650 mV (SHE) (Cu recovery 2.5 cf. 12% over 132 days) due to galvanic interaction between chalcopyrite and pyrite. Dissolution of Cu and Fe was stoichiometric and no pyrite dissolved. Although the chalcopyrite dissolution rate at 750 mV (SHE) was approximately four-fold greater (Cu recovery of 45% within 132 days) as compared to at 650 mV in the presence of pyrite, the galvanic interaction between chalcopyrite and pyrite was negligible. Approximately all of the sulfur from the leached chalcopyrite was converted to S0 at 750 mV, regardless of the presence of pyrite. At this Eh approximately 60% of the sulfur associated with pyrite dissolution was oxidised to S0 and the remaining 40% was released in soluble forms, e.g., SO42. Full article
(This article belongs to the Special Issue Hydrometallurgy) Printed Edition available
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Open AccessReview New Approaches to Aluminum Integral Foam Production with Casting Methods
Metals 2015, 5(3), 1553-1565; https://doi.org/10.3390/met5031553
Received: 25 June 2015 / Revised: 3 August 2015 / Accepted: 21 August 2015 / Published: 28 August 2015
Cited by 6 | PDF Full-text (947 KB) | HTML Full-text | XML Full-text
Abstract
Integral foam has been used in the production of polymer materials for a long time. Metal integral foam casting systems are obtained by transferring and adapting polymer injection technology. Metal integral foam produced by casting has a solid skin at the surface and
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Integral foam has been used in the production of polymer materials for a long time. Metal integral foam casting systems are obtained by transferring and adapting polymer injection technology. Metal integral foam produced by casting has a solid skin at the surface and a foam core. Producing near-net shape reduces production expenses. Insurance companies nowadays want the automotive industry to use metallic foam parts because of their higher impact energy absorption properties. In this paper, manufacturing processes of aluminum integral foam with casting methods will be discussed. Full article
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Open AccessArticle Separation and Recycling for Rare Earth Elements by Homogeneous Liquid-Liquid Extraction (HoLLE) Using a pH-Responsive Fluorine-Based Surfactant
Metals 2015, 5(3), 1543-1552; https://doi.org/10.3390/met5031543
Received: 27 July 2015 / Accepted: 25 August 2015 / Published: 27 August 2015
Cited by 3 | PDF Full-text (422 KB) | HTML Full-text | XML Full-text
Abstract
A selective separation and recycling system for metal ions was developed by homogeneous liquid-liquid extraction (HoLLE) using a fluorosurfactant. Sixty-two different elemental ions (e.g., Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga,
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A selective separation and recycling system for metal ions was developed by homogeneous liquid-liquid extraction (HoLLE) using a fluorosurfactant. Sixty-two different elemental ions (e.g., Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, In, Ir, La, Lu, Mg, Mn, Mo, Nb, Nd, Ni, Os, P, Pb, Pd, Pr, Pt, Re, Rh, Ru, Sb, Sc, Se, Si, Sm, Sn, Sr, Ta, Tb, Te, Ti, Tl, Tm, V, W, Y, Yb, Zn, and Zr) were examined. By changing pH from a neutral or alkaline solution (pH ≥ 6.5) to that of an acidic solution (pH < 4.0), gallium, zirconium, palladium, silver, platinum, and rare earth elements were extracted at >90% efficiency into a sedimented Zonyl FSA® (CF3(CF2)n(CH2)2S(CH2)2COOH, n = 6–8) liquid phase. Moreover, all rare earth elements were obtained with superior extraction and stripping percentages. In the recycling of rare earth elements, the sedimented phase was maintained using a filter along with a mixed solution of THF and 1 M sodium hydroxide aqueous solution. The Zonyl FSA® was filtrated and the rare earth elements were recovered on the filter as a hydroxide. Furthermore, the filtrated Zonyl FSA was reusable by conditioning the subject pH. Full article
(This article belongs to the Special Issue Hydrometallurgy) Printed Edition available
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Open AccessReview Tannins in Mineral Processing and Extractive Metallurgy
Metals 2015, 5(3), 1520-1542; https://doi.org/10.3390/met5031520
Received: 28 July 2015 / Revised: 18 August 2015 / Accepted: 21 August 2015 / Published: 27 August 2015
Cited by 4 | PDF Full-text (811 KB) | HTML Full-text | XML Full-text
Abstract
This study provides an up to date review of tannins, specifically quebracho, in mineral processing and metallurgical processes. Quebracho is a highly useful reagent in many flotation applications, acting as both a depressant and a dispersant. Three different types of quebracho are mentioned
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This study provides an up to date review of tannins, specifically quebracho, in mineral processing and metallurgical processes. Quebracho is a highly useful reagent in many flotation applications, acting as both a depressant and a dispersant. Three different types of quebracho are mentioned in this study; quebracho “S” or Tupasol ATO, quebracho “O” or Tupafin ATO, and quebracho “A” or Silvafloc. It should be noted that literature often refers simply to “quebracho” without distinguishing a specific type. Quebracho is most commonly used in industry as a method to separate fluorite from calcite, which is traditionally quite challenging as both minerals share a common ion—calcium. Other applications for quebracho in flotation with calcite minerals as the main gangue source include barite and scheelite. In sulfide systems, quebracho is a key reagent in differential flotation of copper, lead, zinc circuits. The use of quebracho in the precipitation of germanium from zinc ores and for the recovery of ultrafine gold is also detailed in this work. This analysis explores the wide range of uses and methodology of quebracho in the extractive metallurgy field and expands on previous research by Iskra and Kitchener at Imperial College entitled, “Quebracho in Mineral Processing”. Full article
(This article belongs to the Special Issue Hydrometallurgy) Printed Edition available
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