| 1. |
- Abbasalizadeh, Aida, et al.
(författare)
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Electrochemical Extraction of Rare Earth Metals in Molten Fluorides : Conversion of Rare Earth Oxides into Rare Earth Fluorides Using Fluoride Additives
- 2017
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Ingår i: JOURNAL OF SUSTAINABLE METALLURGY. - : SPRINGER. - 2199-3823 .- 2199-3831. ; 3:3, s. 627-637
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Tidskriftsartikel (refereegranskat)abstract
- In the present research on rare earth extraction from rare earth oxides (REOs), conversion of rare earth oxides into rare earth fluorides with fluoride fluxes is investigated in order to overcome the problem of low solubility of the rare earth oxides in molten fluoride salts as well as the formation of oxyfluorides in the fluorination process. Based on thermodynamic calculations, a series of experiments were performed for converting the rare earth oxides into rare earth fluorides using AlF3, ZnF2, FeF3, and Na3AlF6 as fluorinating agents in a LiF-Nd2O3 system. The formation of neodymium fluoride as a result of the reactions between these fluxes and neodymium oxide is confirmed. The rare earth fluoride thus formed can subsequently be processed through the electrolysis route in the same reactor, and rare earth metal can be produced as the cathodic deposit. In this concept, the REO dissolution in molten fluorides would become unnecessary due to the complete conversion of the oxide into the fluoride, REF3. The results of XRD and EPMA analysis of the reacted samples indicate that AlF3, ZnF2, and FeF3 can act as strong fluorinating agents for the neodymium oxide giving rise to a complete conversion of neodymium oxide into neodymium fluoride.
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| 2. |
- Allertz, Carl, et al.
(författare)
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Possibility of Sulfur Removal from Ladle Slag by Oxidation in the Temperature Range 1373-1673 K
- 2015
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Ingår i: Journal of Sustainable Metallurgy. - : Springer Science and Business Media LLC. - 2199-3823 .- 2199-3831. ; 1:3, s. 229-239
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Tidskriftsartikel (refereegranskat)abstract
- Experiments were conducted to investigate the possibility of removing sulfur from used ladle slag by oxidation. Slag samples (solid, two-phase mixture, and liquid with a small fraction of solid MgO particles) were subjected to an oxygen-rich atmosphere in the temperature range 1373–1673 K. The sulfur removal from the samples of solid and two-phase mixture was found to be a slow process due to the slow diffusion. The sulfur removal was found to have little dependence on temperature in the range 1373–1573 K. When the slag was mostly liquid (at 1673 K), the sulfur removal was significantly increased. More than 85 % of the sulfur could be removed after 60 min of oxidation in pure oxygen. An increase in oxygen partial pressure was found to increase the desulfurization slightly. Increasing the Al2O3 content in the slag decreased the degree of sulfur removal.
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| 3. |
- Andersson, Anton, et al.
(författare)
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Insights into the Valorization of Electric Arc Furnace Slags as Supplementary Cementitious Materials
- 2023
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Ingår i: Journal of Sustainable Metallurgy. - : Springer. - 2199-3823 .- 2199-3831. ; 10, s. 96-109
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Tidskriftsartikel (refereegranskat)abstract
- The transition to hydrogen-based reduction processes within the iron and steelmaking industry will generate new types of slag compositions that require valorization routes. Using slags as supplementary cementitious materials (SCMs) addresses the carbon dioxide emissions of the cement industry since the SCM requires neither calcination nor clinkering. Conventionally, ironmaking slags from the blast furnace (BF) are recycled as SCMs, i.e., ground granulated BF slag (GGBS). Ideally, future slags from electric arc furnaces (EAFs) operating on hydrogen-based direct reduced iron should be valorized analogously. Since the hydrogen-based process route is not yet realized in an industrial scale, the literature lacks data to support this valorization route, and additionally, literature on scrap-based EAF slags is scarce. Therefore, the present study aimed to offer insights into the utilization of ore-based EAF slags as SCMs based on an industrial slag sample from an EAF operating on hot briquetted iron. The slag was remelted, modified, and water-granulated in laboratory scale, and its performance as an SCM was compared to water-granulated ladle slag and two commercial GGBS. The results showed promising reactivities measured using the R3 isothermal calorimeter-based testing protocol. Based on the comparison to GGBS, the study indicated that generating reactive and appropriate SCMs from EAF slags will partly be a challenge in balancing the crystallization of the MeO-type solid solution rich in magnesia and addressing the iron oxide content in the amorphous phase.
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| 4. |
- Andersson, Anton, et al.
(författare)
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Upgrading of Blast Furnace Sludge and Recycling of the Low-Zinc Fraction via Cold-bonded Briquettes
- 2019
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Ingår i: Journal of Sustainable Metallurgy. - : Springer. - 2199-3823 .- 2199-3831. ; :3, s. 350-361
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Tidskriftsartikel (refereegranskat)abstract
- Depending on the operation of the blast furnace (BF), the main outlet of zinc from the furnace is more or less via the BF dust and sludge. As the dust is recycled to the BF, the sludge has to be de-zinced prior to recycling to prevent the accumulation of zinc in the BF. De-zincing and recycling of the low-zinc fraction via sinter have been reported. However, no research con-cerning recycling of upgraded BF sludge via cold-bonded briquettes has been performed. In the present study, a fine-grained BF sludge with low zinc content, generated by a BF operating on a ferrous burden of 100% pellets, was upgraded using the tornado process. The process simultaneously dried and separated the BF sludge into a high-zinc and a low-zinc fraction. The feasibility of recycling the low-zinc fraction to the BF using cold-bonded briquettes was studied on a laboratory-scale BF shaft simulator. On comparison with a reference briquette, the experiments indicated that 10 wt% of the upgraded BF sludge can be added to the briquette without negatively affecting the reducibility. Higher additions were found to render the briquette less reduced compared to the reference under test conditions corresponding to the central part of the BF. The strength of the briquettes was not compromised with the addition of the upgraded BF sludge, and a decision to study the briquettes in the LKAB experimental blast furnace was made in order to evaluate the behavior under actual BF conditions.
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| 5. |
- Babanejad, Safoura, et al.
(författare)
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High-Temperature Behavior of Spent Li-Ion Battery Black Mass in Inert Atmosphere
- 2022
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Ingår i: Journal of Sustainable Metallurgy. - : Springer Nature. - 2199-3823 .- 2199-3831. ; 8, s. 566-581
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Tidskriftsartikel (refereegranskat)abstract
- The increased demand for Li-ion batteries has prompted the scientific community to improve recycling routes in order to reuse the valuable materials in batteries. After their end-of-life, the batteries are collected, discharged, and mechanically disintegrated, generating plastic and metallic streams that are recycled directly; this leaves behind a small particle size fraction known as black mass (BM). BM is composed mainly of graphite and Li-metal complex oxides. Pyrometallurgy is a route known for recycling of BM, in which identifying the BM’s behavior at high temperatures is essential. In this study, two types of BM are characterized in two fractions of 150–700 µm and smaller than 150 µm. The thermal behavior of the BM is studied with thermal analysis techniques. The analyses demonstrate that the mineralogical and morphological properties of the two fractions do not significantly differ, while the amounts of C and organic materials might vary. When the BM was thermally treated, the binders decomposed until a temperature of 500 ℃ was reached, where the volatilization of hydrocarbons was observed, although F mostly persisted in the BM. The Li-metal oxide was partially reduced to lower oxides and Li carbonate at ⁓ 600 ℃, and the main mass loss was caused by carbothermic reduction immediately thereafter. As the products of this process, metallic Co and Ni phases were formed, and part of the graphite remained unreacted. Regarding the Li behavior, it was observed that in the presence of Al, AlLiO2 is the most likely composition to form, and it changes to LiF by increasing the F concentration in the composition.
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| 6. |
- Babanejad, Safoura, et al.
(författare)
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Mechanical Activation-Assisted Recovery of Valuable Metals from Black Mass in the Form of Fe/Cu Alloys
- 2023
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Ingår i: Journal of Sustainable Metallurgy. - : Springer. - 2199-3823 .- 2199-3831. ; 9:2, s. 522-536
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Tidskriftsartikel (refereegranskat)abstract
- Pyrometallurgy is a popular industrial method that is employed in the recovery of valuable elements from black mass (BM), which is produced by pretreatment of Li-ion batteries. This method struggles with some downsides, such as the incineration of graphite and high energy consumption. In this study, the goal is to utilize graphite in the BM to produce a master alloy in an attempt to decrease the energy input requirement. To achieve this, metal oxides (Fe2O3 and CuO) are added to the BM to produce an Fe/Cu-based alloy containing Co/Ni as alloying elements. Mechanical activation is also employed to decrease the energy requirement and to increase the amount of metal oxide that can be reduced by the graphite in the BM. The results revealed that it is possible to produce the aforementioned alloys, the efficiency of which can be improved by applying mechanical activation. After 1 h of milling, the required heat flow for producing Fe- and Cu-based alloys is lowered for ⁓10 and ⁓25 kWh, respectively. Plus, the direct CO2 emission decreases for 13-17% in the iron system and 43-46% in the copper system.
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| 7. |
- Beheshti, Reza, et al.
(författare)
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Black Dross Processing : Utilization of Black Dross in the Production of a Ladle Fluxing Agent
- 2017
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Ingår i: Journal of Sustainable Metallurgy. - : Springer. - 2199-3831 .- 2199-3823. ; 3:2, s. 265-273
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, black dross (BD) residue, a hazardous by-product generated during secondary aluminum production, has been evaluated as a possible raw material for the production of a calcium aluminate-based ladle fluxing agent to be used in the steel industry. The thermally treated BD [pretreated black dross (PBD)] used as a starting material, consisted of approximately 49.5 ± 3.5 wt% alumina and 0.3 wt% chloride. The effects of different process parameters on the properties of the produced flux were experimentally investigated, i.e., the CaO/Al2O3 ratio, the sintering temperature and time, and the cooling medium. The prepared samples were all sintered in a rapid high-temperature inductive furnace, and later characterized by SEM–EDS, XRD, XRF, and DTA/TG analyses. Dissolution tests were also performed using a synthetic slag simulating the carryover. Based on the presently obtained results, it can be concluded that the utilization of PBD as the alumina source during the production of a calcium aluminate fluxing agent shows promising results, and the optimum process conditions were established to be 1523 K for 15 min as the sintering temperature and time, water as the cooling medium, and a CaO/Al2O3 ratio of 0.94. Utilizing PBD as a raw material in the production of a value-added product would significantly reduce the need for the disposal of BD as a waste, and thereby help to decrease the overall environmental impact. It would also provide economic benefit to both the steel and aluminum industry.
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| 8. |
- Compañero, Reinol Josef, et al.
(författare)
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Circular Steel: How Information and Actor Incentives Impact the Recyclability of Scrap
- 2021
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Ingår i: Journal of Sustainable Metallurgy. - : Springer Nature. - 2199-3823 .- 2199-3831.
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Tidskriftsartikel (refereegranskat)abstract
- Recycling plays a vital role in preserving resources like steel and consequently in a circular economy. Scrap dealers and steel mills, the main business units in this system, often encounter opposing financial and sustainability incentives in using scrap as feedstock because regular sorting and scrap-preparation infrastructure cannot deal with the increasing complexity of steel scrap. Mismatches between the inputs and the target composition of the recycled steel result in trade-offs that favor the economics at the expense of resource efficiency. By examining literature and interviewing several actors, different scrap characteristics were identified as dimensions of scrap quality. Quality is typically associated with chemical composition, which is important, but this study aims to elaborate the concept of quality further and to connect it to the realities of scrapyard operations. Industry actors have different definitions for desired content, physical condition, shape and size, and homogeneity, based on their needs. Very few studies examine these details. Additionally, the relationship of quality and the level of information about the characteristics of the material was established. Having more definitive information on scrap increases opportunities for resource-efficient actions. This work offers an alternative perspective on how to address issues pertinent to recycling.
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| 9. |
- De Colle, Mattia, et al.
(författare)
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Study of the Hydration Behavior of Synthetic Ferropericlase with LowIron Oxide Concentrations to Prevent Swelling in Steel Slags
- 2021
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Ingår i: Journal of Sustainable Metallurgy. - : Springer Nature. - 2199-3831 .- 2199-3823.
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Tidskriftsartikel (refereegranskat)abstract
- Steel slags generally swell when subjected to water or humidity, which prevents proper recycling in the cement or asphaltindustries. The MgO and CaO phases in steel slags are responsible for this phenomenon, as both minerals easily absorb waterto form their respective hydroxides. MgO is often present in steel slags in a solid solution with several oxides, constitutingthe so-called RO phase. This study investigates the hydration rate of an RO phase consisting of FeO and MgO called ferropericlase.The material was synthesized in a laboratory furnace by sintering a FeO–MgO powder mixture with varying initialFeO contents (approximately 10, 15, and 20 wt%). Thereafter, electron probe micro-analyzer (EPMA) and X-ray diffraction(XRD) spectroscopies were used to characterize the structure of the samples, which were mainly composed of ferropericlaseand an exsolution of magnesioferrite. Also, Mössbauer spectra showed that the total ferrous iron proportion (Fe2+/ΣFe) ofthe sintered samples was in the range of 0.55–0.72. To measure the hydration behavior, the samples in powder form werecured in an autoclave at an H2Opartial pressure of 2 atm. Thereafter, thermal gravimetric analysis (TGA) was performed tomeasure the amount of water absorbed during the autoclave curing from the mass drop associated with the dehydration ofthe hydroxide. The study found a linear correlation between the initial FeO content and the weight loss after TGA, with areduction down to 6% in the sample with an initial FeO content of 20 wt% content compared to pure MgO.
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| 10. |
- Gergoric, Marino, 1989, et al.
(författare)
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Characterization and Leaching of Neodymium Magnet Waste and Solvent Extraction of the Rare-Earth Elements Using TODGA
- 2017
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Ingår i: Journal of Sustainable Metallurgy. - : Springer Science and Business Media LLC. - 2199-3831 .- 2199-3823. ; 3:3, s. 638-645
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Tidskriftsartikel (refereegranskat)abstract
- The rare-earth elements (REEs) are considered as some of the most critical elements in the EU and the USA today. E-scrap, such as end-of-life neodymium magnets, could be a viable secondary source for the recovery of these elements. Neodymium magnets (NdFeB) consist of considerable amounts of Nd, Dy, Pr, and some other REEs, depending on the specific application. Apart from REEs, neodymium magnets are made up of around 60% iron, which can pose a challenge in their recycling. For example, iron can be dissolved along with other elements during leaching or co-extracted during solvent extraction. In this work, extraction of REEs with TODGA (tetraoctyl-diglycolamide) from a real leachate, obtained by neodymium magnet powder dissolution in nitric acid, was studied. The goal was to selectively extract the REEs from other elements in the solution. TODGA was used as the extracting agent due to its selective extraction properties for REEs and other f-block elements. The influence of the diluent on the overall extraction and the selectivity of the extraction was studied in order to determine application feasibility of future processes. To this end, experiments using Solvent 70 (hydrocarbons C11-C14, ae 0.5 wt% aromatics), hexane, toluene, cyclohexanone and 1-octanol as the diluents were performed. TODGA has shown good selectivity between REEs and other elements in solution under almost all conditions, reaching the highest distribution ratios of REEs in the aliphatic diluents, while the distribution ratios of other non-REEs reach a mere value of 0.1. An exception was cyclohexanone, which has the ability to extract small amounts of ions itself. The highest separation factors between Dy and the light REEs (Nd and Pr) were observed with a 0.01 M solution of TODGA in Solvent 70. REEs, as group, were extracted with 0.1 M solutions of TODGA in all diluents except for cyclohexanone, which led to extraction of Al and B at amounts greater than 10%. Stripping with over 98% efficiency was achieved using MQ water in one step.
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