Special Issue "Recycling of Metals"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (30 April 2016)

Special Issue Editor

Guest Editor
Prof. Dr. Corby G. Anderson

Kroll Institute for Extractive Metallurgy, Colorado School of Mines, Golden, CO 80401, USA
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Special Issue Information

Dear Colleagues,

This Special Issue will focus on the recycling of metals using mineral processing, hydrometallurgy, electrometallurgy, and pyrometallurgy. The source of the metals may be recycled engineered materials, sludges, slags, tailings, or other similar materials.

Prof. Dr. Corby G. Anderson
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Metals
  • Recycle
  • Reuse
  • Reclaim
  • Hydrometallurgy
  • Electrometallurgy
  • Pyrometallurgy
  • Mineral processing

Published Papers (11 papers)

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Research

Open AccessArticle One-Step Extraction of Antimony in Low Temperature from Stibnite Concentrate Using Iron Oxide as Sulfur-Fixing Agent
Metals 2016, 6(7), 153; doi:10.3390/met6070153
Received: 28 April 2016 / Revised: 5 June 2016 / Accepted: 16 June 2016 / Published: 7 July 2016
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Abstract
A new process for one-step extraction of antimony in low temperature from stibnite concentrate by reductive sulfur-fixation smelting in sodium molten salt, using iron oxide as sulfur-fixing agent, was presented. The influences of molten salt addition and composition, ferric oxide dosage, smelting temperature
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A new process for one-step extraction of antimony in low temperature from stibnite concentrate by reductive sulfur-fixation smelting in sodium molten salt, using iron oxide as sulfur-fixing agent, was presented. The influences of molten salt addition and composition, ferric oxide dosage, smelting temperature and duration on extraction efficiency of antimony were investigated in details, respectively. The optimum conditions were determined as follows: 1.0 time stoichiometric requirement (α) of mixed sodium salt (αsalt = 1.0), WNaCl:Wsalt = 40%, αFe2O3 = 1.0, Wcoke:Wstibnite = 40%, where W represents weight, smelting at 850 °C (1123 K) for 60 min. Under the optimum conditions, the direct recovery rate of antimony can reach 91.48%, and crude antimony with a purity of 96.00% has been achieved. 95.31% of sulfur is fixed in form of FeS in the presence of iron oxide. Meanwhile, precious metals contained in stibnite concentrate are enriched and recovered comprehensively in crude antimony. In comparison to traditional antimony pyrometallurgical process, the smelting temperature of present process is reduced from 1150–1200 °C (1423–1473 K) to 850–900 °C (1123–1173 K). Sulfur obtained in stibnite is fixed in FeS which avoids SO2 emission owing to the sulfur-fixing agent. Sodium salt can be regenerated and recycled in smelting system when the molten slag is operated to filter solid residue. The solid residue is subjected to mineral dressing operation to obtain iron sulfide concentrate which can be sold directly or roasted to regenerate into iron oxide. Full article
(This article belongs to the Special Issue Recycling of Metals)
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Open AccessArticle Designing of Synergistic Waste Mixtures for Multiphase Reactive Smelting
Metals 2016, 6(6), 138; doi:10.3390/met6060138
Received: 29 March 2016 / Revised: 20 May 2016 / Accepted: 24 May 2016 / Published: 8 June 2016
Cited by 1 | PDF Full-text (3948 KB) | HTML Full-text | XML Full-text
Abstract
Electric arc furnace (EAF) dust, together with a mill scale and coke were smelted in a laboratory electric arc furnace. These metallurgical wastes consist of a many different phases and elements, making the reaction process complex. Thermo-chemical analysis of the reactions in metal,
[...] Read more.
Electric arc furnace (EAF) dust, together with a mill scale and coke were smelted in a laboratory electric arc furnace. These metallurgical wastes consist of a many different phases and elements, making the reaction process complex. Thermo-chemical analysis of the reactions in metal, slag, and gas phases was done, and used for modeling of the mixture composition and energy consumption required for smelting. Modelling was performed with the software named RikiAlC. The crude ZnO, slag, and metal phase were analyzed using the atomic absorption spectrometry (AAS), the optical emission spectrometry with inductively coupled plasma (ICP-OES), the X-ray diffraction (XRD), the scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS), and reflected and transmitted light microscopy. Also, in order to follow the behavior of this process the exhausted gases were monitored. The synergetic effects of the designed mixture may be recognized in minimizing energy consumption for the smelting process, improving the product yield efficiency, and reducing the negative environmental effects. Full article
(This article belongs to the Special Issue Recycling of Metals)
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Open AccessArticle Synchronous Upgrading Iron and Phosphorus Removal from High Phosphorus Oolitic Hematite Ore by High Temperature Flash Reduction
Metals 2016, 6(6), 123; doi:10.3390/met6060123
Received: 31 March 2016 / Revised: 11 May 2016 / Accepted: 11 May 2016 / Published: 24 May 2016
Cited by 4 | PDF Full-text (5754 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, an effective method was developed to remove phosphorus and upgrade iron from high phosphorus oolitic hematite ore by high temperature flash reduction—a wet magnetic separation process. A thermodynamic analysis of iron and phosphorus mineral reactions and experiments with Fe-P separation
[...] Read more.
In this paper, an effective method was developed to remove phosphorus and upgrade iron from high phosphorus oolitic hematite ore by high temperature flash reduction—a wet magnetic separation process. A thermodynamic analysis of iron and phosphorus mineral reactions and experiments with Fe-P separation process were performed, and the mechanism of phosphorus removal and beneficiation of iron is discussed as well. The results show that under the proper conditions, a final metallic iron powder assaying over 91% Fe and 0.25% P was obtained with iron recovery of 90% and phosphorus removal rate of 91.79% using the new process, indicating that the high temperature flash reduction process is a feasible and efficient way to process this kind of complex and refractory iron ore. Moreover, sodium sulfate is found to be capable of improving the removal of phosphorus and the upgrading of iron, as well as enhancing the growth of metallic iron grains significantly for higher recovery of iron. Full article
(This article belongs to the Special Issue Recycling of Metals)
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Open AccessArticle Roles of Mineralogical Phases in Aqueous Carbonation of Steelmaking Slag
Metals 2016, 6(5), 117; doi:10.3390/met6050117
Received: 29 March 2016 / Revised: 2 May 2016 / Accepted: 5 May 2016 / Published: 18 May 2016
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Abstract
Mineralogical phases of steelmaking slags have significant influences on the carbonation of the slags. In this paper, the effects of temperature and reaction time on the conversion of calcium-related phases and the carbonation degree of a slag sample were studied. The experimental conditions
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Mineralogical phases of steelmaking slags have significant influences on the carbonation of the slags. In this paper, the effects of temperature and reaction time on the conversion of calcium-related phases and the carbonation degree of a slag sample were studied. The experimental conditions were a liquid-to-solid ratio of 20 mL/g, a carbon dioxide flow rate of 1 L/min and a slag particle size of 38–75 μm. The results show that the optimum carbonation temperature and reaction time are 60 °C and 90 min, respectively, and calcite phase content is about 26.78% while the conversion rates of Ca3Al2O6, CaSiO3, Ca2SiO4 and free CaO are about 40%, 42.46%, 51% and 100%, respectively, and the carbon dioxide sequestration efficiency is about 170 g/kg slag. Full article
(This article belongs to the Special Issue Recycling of Metals)
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Open AccessArticle Effects of Basicity and MgO in Slag on the Behaviors of Smelting Vanadium Titanomagnetite in the Direct Reduction-Electric Furnace Process
Metals 2016, 6(5), 107; doi:10.3390/met6050107
Received: 29 March 2016 / Revised: 21 April 2016 / Accepted: 4 May 2016 / Published: 10 May 2016
Cited by 6 | PDF Full-text (17622 KB) | HTML Full-text | XML Full-text
Abstract
The effects of basicity and MgO content on reduction behavior and separation of iron and slag during smelting vanadium titanomagnetite by electric furnace were investigated. The reduction behaviors affect the separation of iron and slag in the direct reduction-electric furnace process. The recovery
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The effects of basicity and MgO content on reduction behavior and separation of iron and slag during smelting vanadium titanomagnetite by electric furnace were investigated. The reduction behaviors affect the separation of iron and slag in the direct reduction-electric furnace process. The recovery rates of Fe, V, and Ti grades in iron were analyzed to determine the effects of basicity and MgO content on the reduction of iron oxides, vanadium oxides, and titanium oxides. The chemical compositions of vanadium-bearing iron and main phases of titanium slag were detected by XRF and XRD, respectively. The results show that the higher level of basicity is beneficial to the reduction ofiron oxides and vanadium oxides, and titanium content dropped in molten iron with the increasing basicity. As the content of MgO increased, the recovery rate of Fe increased slightly but the recovery rate of V increased considerably. The grades of Ti in molten iron were at a low level without significant change when MgO content was below 11%, but increased as MgO content increased to 12.75%. The optimum conditions for smelting vanadium titanomagnetite were about 11.38% content of MgO and quaternary basicity was about 1.10. The product, vanadium-bearing iron, can be applied in the converter steelmaking process, and titanium slag containing 50.34% TiO2 can be used by the acid leaching method. Full article
(This article belongs to the Special Issue Recycling of Metals)
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Open AccessArticle Oxidation Kinetics and Oxygen Capacity of Ti-Bearing Blast Furnace Slag under Dynamic Oxidation Conditions
Metals 2016, 6(5), 105; doi:10.3390/met6050105
Received: 23 December 2015 / Revised: 20 April 2016 / Accepted: 21 April 2016 / Published: 6 May 2016
Cited by 3 | PDF Full-text (2897 KB) | HTML Full-text | XML Full-text
Abstract
The oxidation kinetics of low valence titanium and iron in Ti-bearing blast furnace slag were investigated, the activation energies were calculated, which are 461.1 and 437.3 kJ/mol, respectively. The results illustrate that the oxidation process of Ti3+ in the slag is controlled
[...] Read more.
The oxidation kinetics of low valence titanium and iron in Ti-bearing blast furnace slag were investigated, the activation energies were calculated, which are 461.1 and 437.3 kJ/mol, respectively. The results illustrate that the oxidation process of Ti3+ in the slag is controlled by chemical reactions. However, the chemical reaction between oxygen and iron, between slag and gas, is the determining step of the iron oxidation process. The effects of the isothermal oxidation on the content of Fe2O3, FeM, FeO, and FeT in the slag are discussed. The Fe2+ and Ti3+ in the molten slag were oxidized at high temperatures. Oxygen affinity of the slag can be described using oxygen capacity. The oxygen capacity of Ti-bearing blast furnace slag was investigated during the dynamic oxidation process, the results indicates that the oxygen capacity of the slag decreased with increasing oxidation time during the dynamic oxidation process. Full article
(This article belongs to the Special Issue Recycling of Metals)
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Open AccessArticle Processing Mineralogy Study on Lead and Zinc Oxide Ore in Sichuan
Metals 2016, 6(4), 93; doi:10.3390/met6040093
Received: 16 February 2016 / Revised: 8 April 2016 / Accepted: 9 April 2016 / Published: 22 April 2016
Cited by 1 | PDF Full-text (1615 KB) | HTML Full-text | XML Full-text
Abstract
The processing mineralogy characteristics of an oxidized lead-zinc ore from Sichuan were studied systematically using numerous modern instruments. Results showed that lead and zinc oxide content in the ore exceeded the minimum industrial grade, and also included a relatively high concentration of silver
[...] Read more.
The processing mineralogy characteristics of an oxidized lead-zinc ore from Sichuan were studied systematically using numerous modern instruments. Results showed that lead and zinc oxide content in the ore exceeded the minimum industrial grade, and also included a relatively high concentration of silver and iron. This ore is composed of many different minerals. Major zinc-containing minerals include sphalerite, hemimorphite, smithsonite, hydrozincite, zinc-containing baileychlore, and zinc-containing dolomite and calcite. Lead-containing minerals are primarily galena and cerussite with small amounts of dechenite, cesaronite, anglesite, limonite and coronadite. Gangue minerals include dolomite and calcite. Dissemination size for the main minerals ranges from medium (0.04 mm) to fine (0.02 mm). All the valuable minerals are well liberated, including galena, sphalerite, cerussite, calamine, and smithsonite. However, the dissemination relationships are complex. Lead is concentrated mainly in galena and cerussite, while zinc occurs primarily in sphalerite, calamine, and smithsonite. The theoretical recovery for lead and zinc were estimated at 72% and 67%, respectively. Full article
(This article belongs to the Special Issue Recycling of Metals)
Open AccessArticle Preparation of Metallic Iron Powder from Pyrite Cinder by Carbothermic Reduction and Magnetic Separation
Metals 2016, 6(4), 88; doi:10.3390/met6040088
Received: 16 February 2016 / Revised: 31 March 2016 / Accepted: 11 April 2016 / Published: 16 April 2016
Cited by 3 | PDF Full-text (4971 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The reduction and magnetic separation procedure of pyrite cinder in the presence of a borax additive was performed for the preparation of reduced powder. The effects of borax dosage, reduction temperature, reduction time and grinding fineness were investigated. The results show that when
[...] Read more.
The reduction and magnetic separation procedure of pyrite cinder in the presence of a borax additive was performed for the preparation of reduced powder. The effects of borax dosage, reduction temperature, reduction time and grinding fineness were investigated. The results show that when pyrite cinder briquettes with 5% borax were pre-oxidized at 1050 °C for 10 min, and reduced at 1050 °C for 80 min, with the grinding fineness (<0.44 mm) passing 81%, the iron recovery was 91.71% and the iron grade of the magnetic concentrate was 92.98%. In addition, the microstructures of the products were analyzed by optical microscope, scanning electron microscope (SEM), and mineralography, and the products were also studied by the X-ray powder diffraction technique (XRD) to investigate the mechanism; the results show that the borax additive was approved as a good additive to improve the separation of iron and gangue. Full article
(This article belongs to the Special Issue Recycling of Metals)
Open AccessArticle Reaction Behavior of Phosphorus in Coal-Based Reduction of an Oolitic Hematite Ore and Pre-Dephosphorization of Reduced Iron
Metals 2016, 6(4), 82; doi:10.3390/met6040082
Received: 8 January 2016 / Revised: 29 March 2016 / Accepted: 1 April 2016 / Published: 8 April 2016
Cited by 2 | PDF Full-text (3665 KB) | HTML Full-text | XML Full-text
Abstract
Coal-based reduction followed by magnetic separation is an effective way to recover iron from high phosphorus-containing oolitic hematite ore. Given that high quantities of dephosphorization agent are needed to obtain low phosphorus reduced iron, a novel approach is proposed by the authors. Without
[...] Read more.
Coal-based reduction followed by magnetic separation is an effective way to recover iron from high phosphorus-containing oolitic hematite ore. Given that high quantities of dephosphorization agent are needed to obtain low phosphorus reduced iron, a novel approach is proposed by the authors. Without prior phosphorus removal, the phosphorus was enriched in the reduced iron during a reduction process, then high-phosphorus reduced iron was refined to low phosphorus molten iron and high phosphorus dephosphorization slag to be used as a phosphate fertilizer. The influences of various parameters, including the reduction temperature, the reduction time, and the C/O molar ratio, on the reaction behavior of phosphorus during reduction process were studied. Experimental results indicate that a higher reduction temperature, a longer reduction time, or a higher C/O molar ratio was favorable for the reduction of apatite to phosphorus and the enrichment of phosphorus in reduced iron. X-ray diffraction (XRD) analysis demonstrated that the apatite was reduced to phosphorus and Ca2SiO4 (or Ca(Al2Si2O8)) in the presence of SiO2 and Al2O3, whilst the phosphorus enriched in reduced iron formed Fe3P. The migration behavior of phosphorus was investigated using line scanning analysis of reduction products at different reduction times. The results show that the phosphorus primarily existed in the slag phase 10 min before reduction, and a large amount of phosphorus migrated into iron phase from slag phase with a reduction time of 40 min. The phosphorus content in the iron phase only slightly changed after 50 min. The pre-dephosphorization of reduced iron was performed at 1873 K, indicating a higher basicity or FetO content of CaO-based slag was beneficial to dephosphorization of the reduced iron. Full article
(This article belongs to the Special Issue Recycling of Metals)
Open AccessArticle Recovery of Vanadium from H2SO4-HF Acidic Leaching Solution of Black Shale by Solvent Extraction and Precipitation
Metals 2016, 6(3), 63; doi:10.3390/met6030063
Received: 21 January 2016 / Revised: 28 February 2016 / Accepted: 3 March 2016 / Published: 14 March 2016
Cited by 1 | PDF Full-text (1557 KB) | HTML Full-text | XML Full-text
Abstract
The recovery of vanadium from sulfuric and hydrofluoric mixed acid solutions generated by the direct leaching of black shale was investigated using solvent extraction and precipitation methods. The process consisted of reduction, solvent extraction, and stripping, followed by precipitation and calcination to yield
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The recovery of vanadium from sulfuric and hydrofluoric mixed acid solutions generated by the direct leaching of black shale was investigated using solvent extraction and precipitation methods. The process consisted of reduction, solvent extraction, and stripping, followed by precipitation and calcination to yield vanadium pentoxide. The influence of various operating parameters on the extraction and recovery of vanadium was studied. Vanadium (IV) was selectively extracted using a mixture of 10% (v/v) di(2-ethylhexyl)phosphoric acid and 5% (v/v) tri-n-butylphosphate in sulfonated kerosene. Using six extraction and five stripping stages, the extraction efficiency for vanadium was 96.7% and the stripping efficiency was 99.7%. V2O5 with a purity of 99.52% was obtained by oxidation of the loaded strip solution and precipitation of ammonium polyvanadate at pH 1.8 to 2.2, followed by calcination of the dried precipitate at 550 °C for 2 h. It was concluded that the combination of solvent extraction and precipitation is an efficient method for the recovery of vanadium from a multi-element leach solution generated from black shale. Full article
(This article belongs to the Special Issue Recycling of Metals)
Open AccessArticle Upgrading of High-Aluminum Hematite-Limonite Ore by High Temperature Reduction-Wet Magnetic Separation Process
Metals 2016, 6(3), 57; doi:10.3390/met6030057
Received: 8 January 2016 / Revised: 22 February 2016 / Accepted: 3 March 2016 / Published: 8 March 2016
Cited by 3 | PDF Full-text (4040 KB) | HTML Full-text | XML Full-text
Abstract
The huge consumption of iron ores in China has attracted much attention to utilizing low grade complex iron resources, such as high-aluminum hematite-limonite ore, which is a refractory resource and difficult to upgrade by traditional physical concentration processes due to the superfine size
[...] Read more.
The huge consumption of iron ores in China has attracted much attention to utilizing low grade complex iron resources, such as high-aluminum hematite-limonite ore, which is a refractory resource and difficult to upgrade by traditional physical concentration processes due to the superfine size and close dissemination of iron minerals with gangue minerals. An innovative technology for a high temperature reduction-magnetic separation process was studied to upgrade a high-aluminum iron ore assaying 41.92% Fetotal, 13.74% Al2O3 and 13.96% SiO2. The optimized results show that the final metal iron powder, assaying 90.46% Fetotal, was manufactured at an overall iron recovery of 90.25% under conditions as follows: balling the high aluminum iron ore with 15% coal blended and at 0.3 basicity, reducing the dried pellets at 1350 °C for 25 min with a total C/Fe mass ratio of 1.0, grinding the reduced pellets up to 95%, passing at 0.074 mm and magnetically separating the ground product in a Davis Tube at a 0.10-T magnetic field intensity. The metal iron powder can be used as the burden for an electric arc furnace (EAF). Meanwhile, the nonmagnetic tailing is suitable to produce ceramic, which mainly consists of anorthite and corundum. An efficient way has been found to utilize high-aluminum iron resources. Full article
(This article belongs to the Special Issue Recycling of Metals)
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