Metallurgy Aluminum Research Articles

Aluminum Alloys as Anodes for Aluminum Batteries

The development of batteries based on metals alternative to Lithium (e.g. Na, Mg, Zn, Al) requires the investigation of new electrodes and electrolytes. [1,2].This is particularly true in the case of non-aqueous Aluminum batteries which typically include a pure (>99.8%) Aluminum anode which: a) suffer of poor cycling stability and low coulombic efficiency; b) is particularly subjected to dendrite growth; c) can undergo to corrosion phenomena upon cycling; and d) show a poor compatibility toward chloroaluminated electrolytes [3].In this regard, the development of Aluminum alloys, alternative to pure Al anodes, is a challenging task which is barely investigated in the field of Aluminum ion batteries and requires experience in both battery electrochemistry and Aluminum metallurgy and casting.In this scenario, the proposed work investigates the synthesis and characterization of ternary Aluminum, alloys comprising Si, Ti and B as alloying elements, as anodes for Al-ion batteries [4]. Deposition/stripping measurements, impedance spectroscopy, metallographic analysis, EDXS and XRD techniques unveil the complex interplay existing between the microstructures of the alloys and the obtained electrochemical performance. It is demonstrated that a remarkable improvement in the: a) oxidation/reduction currents and overvoltages; and b) interfacial stability with the electrolyte; can be obtained, with respect to a conventional Al anode. Results allow to demonstrate that the investigation of Aluminum alloys can be crucial for the development of future Aluminum batteries.[1] F Bertasi, C Hettige, F Sepehr, X Bogle, G Pagot, K Vezzù, E Negro, S J Paddison, S G Greenbaum, M Vittadello, V Di Noto, ChemSusChem, 2015, 8 (18), 3069-3076[2] F Bertasi, F Sepehr, G Pagot, SJ Paddison, V Di Noto, Advanced Functional Materials 2016, 26 (27), 4860-4865[3] Y Zhang, S Liu, Y Ji, J Ma, H Yu, Advanced Materials 2018, 30 (38), 1706310[4] Italian Patent Application n° 102022000024522

Selective separation of Al, Fe, and Ti from red mud leachate by Fe-Ti iso precipitate flotation and reduction hydrolysis process: Ions selective chelation and separation mechanism

Bauxite residue (red mud) is a typical solid waste discharged from the aluminum metallurgy industry and can be considered as an alternative resource for the recovery of iron (Fe), aluminum (Al), and titanium (Ti). Acid leaching is an effective technique for the simultaneous extraction of valuable metals from red mud, whereas the leachate with various metals confronts the difficulty of metals separation. In this work, a selective separation and recovery of Fe, Al and Ti from red mud leachate by the preferential Fe-Ti iso precipitate flotation followed by a reduction-hydrolyzation process was proposed. In the iso precipitate flotation process, the cupferron was acted as an Fe-Ti synchronous chelation agent and hexadecyl trimethyl ammonium bromide (CTAB) was used as an anionic collector for the flotation separation of Fe-Ti chelate. The generated fine hydrophobic chelates are rapidly separated from solution by flotation with the assistance of CTAB, in which 99.3% Fe and 99.8% Ti were transferred into the flotation product, while 96.7% Al remained in the leachate, realizing the first separation of Al. Reduction-hydrolyzation was further conducted to separate Ti and Fe from the dissolving solution of the flotation product. Hydrolysis thermodynamic analysis indicated that the required hydrolysis pH range of Fe2+ was much different from that of TiO2+ and Ti3+. After selective reduction of Fe3+ to Fe2+ by KI, 99.8% Ti was concentrated in the residue while 94.8% Fe remained in the solution. Eventually, the comprehensive recoveries of Fe, Ti, and Al are 94.1%, 99.7%, and 96.7%, respectively.

Development and investigation of the technological process of plasma carbothermal reduction of slag from secondary metallurgy of aluminum

Based on a critical analysis of the current state and prospects of development of the problem of pyrometallurgical recovery/extraction of aluminum from aluminum-bearing industrial waste, the need to replace traditional, electrocarbonothermic processes and melting process units with innovative, plasma carbothermal processes and furnace-reactors, with the possibility of reverse feeding and recovery of gasified during melting metal and metal oxide components is substantiated. On the basis of this analysis a new technological scheme of smelting with a new design of plasma-arc furnace-reactor, which provides a solution to the problem using a special hollow double-shell graphite cathode connected to the system of circulating supply of gases separated from the reaction zone, was developed and presented. The proposed technological scheme also differs in the use of such highly active liquid and gaseous reagents as carbon-containing reducing agents as calcium carbide (CaC2) and methane (CH4). The main features of chemism of reducing processes are described. It is shown that by replacing traditional coke with anodized calcium carbide and natural gas (methane) the recovery rate of aluminum oxide (Al 29-34%) and silica (SiO2) and hematite (Fe2O3) present with it increases to 80-99%. Specific power consumption is reduced by 35-40%, the 90-95% reduction in the loss of target elements, the 80% reduction in the emission of greenhouse carbon dioxide, which is replaced by a very valuable recyclable synthesis gas - CO-H2. By additionally feeding separate portions of quartzite and steel-rolling scale in the furnace-reactor, a complex alloy-ligature of Fe-Si-Al-Ca system is melted, with the ratio of components: 1:[1.3-2]:[1.3-1.2]:[0.9-1.25]. With the introduction into industrial practice of the plasma carbothermal process of aluminum reduction from secondary aluminum dumping slags accumulated in the world (4 million tons/year), it will be possible to return up to 1-1.5 million tons/year of aluminum to the production processing cycle.

Magnetization of Bauxite Residue to Enhance the Removal Efficiency Towards Heavy Metals.

Bauxite residues are a mass of industrial wastes derived from aluminum metallurgy. This work provided a simple pyrolysis method to magnetize the bauxite residue to serve as a magnetic adsorbent towards heavy metals removal. The X-ray diffraction patterns and Mossbauer spectrum results confirmed the partial reduction of iron species with an obvious enhancement in magnetization. The magnetized bauxite residue exhibited excellent removal efficiencies for Cu2+, Cd2+ and Pb2+ with maximum adsorption capacities of 219.0mgg-1, 275.4mgg-1, and 100.4mgg-1, which could be quickly separated through a magnet. The adsorption equilibrium data were fitted to the Langmuir isotherm model, while the adsorption kinetics followed a pseudo-first-order model. According to the characterization results, chemical precipitation and sorption was the major mechanism for the removal of Cu2+, Pb2+, and Cd2+. Thus, the magnetized bauxite residue exhibited promising applications for heavy metals removal in wastewater.

Clean dealkalization technology from aluminum industry hazardous tailings-red mud by displacement with Mg-based agent.

Red mud is a kind of strong alkaline hazardous slag discharged from aluminum metallurgy industry. In this study, the water immersion with high temperature and high pressure was developed for the selective dealkalization from red mud by adding Mg-based additives. The removal efficiency of alkali could reach 92% by using 12% MgCl2 with 9 mL/g at 250 °C for 60 min. The MgCl2 was the most effective leaching reagent to promote the decomposion of cancrinite lattice. The new minerals bearing Mg, i.e., chlorite (Mg5Al2Si3O10(OH)8) and pyrope (Mg3Al2Si3O12) could be formed, which was in favor of transforming the structural alkali into the free alkali by the analysis and validation of XRD and SEM-EDS. The dealkalization process was mainly controlled by chemical reactions according to the analysis of unreacted shrinking core model (USCM) of leaching kinetics. The leaching kinetics equation of 1 - (1 - x)1/3 = 32.2 × exp[4582.6 / T] × t was built and the apparent activation energy of 38.1 kJ/mol was obtained. This method may provide a new and cleaner way for the efficient dealkalization of red mud and a basis for the utilization of leaching residue as the soil amendment.

Combined effects of bayer process bauxite waste (red mud) and agricultural waste on technological properties of fired clay bricks

The sustainability of raw materials used in great amounts in the production of building materials used in the construction industry is of great importance. This research investigates the utilization of bayer process bauxite waste and agricultural residues as alternative additive materials for clay replacement to produce eco-friendly porous ceramic bricks. The use of organic and inorganic additives in brick production reduces the consumption of natural clay reserves and the weight of the brick. In addition, these additives have been used as pore formers in brick production to increase thermal performance and waste remediation in ceramic structures for environmental beneficial. Considering these issues, two different types of waste and their combinations were evaluated in brick production in the study. Hazelnut shells (HS) (from 2.5 wt% to 10 wt%), which is an agricultural waste, were used as pore former during firing of brick. On the other hand, this study is related to the evaluation of red mud waste (RM) (from 5 wt% to 30 wt%), which is released in large quantities at the result of Bayer process in the aluminum metallurgy and threatens environmental health, as an alternative raw material in the production of clay bricks. The compacted samples were fired at 900 °C and 1000 °C for 2 h to investigate the effects of firing temperature. Bulk density, water absorption, apparent porosity were determined by Archimedes method. Thermal conductivity and compressive strength of the samples were measured by a thermal conductivity analyzer with a modified transient plane source, and the mechanical test method, respectively. Also, the microstructural and leaching analysis of produced samples was performed. This research have confirmed that the potential use of these wastes decreases the bulk density and mechanical strength and increases the porosity, which leads to higher thermal insulation . The results indicated that samples produced with addition of 10% HS-30% RM exhibited the lowest thermal conductivity values (0.45 W/mK) and the acceptable compressive strength (9 MPa). Also, the effective thermal conductivity coefficient of the perforated brick model designed from this sample is found as 0.112 W/mK in ANSYS Fluent 19.1 Software. Furthermore, the brick samples with a high amount of waste materials show values of leaching toxicity much lower than the specified limits of the Environmental Protection Agency (EPA). The microstructures are also supporting the porosity ratios of brick samples. Based on the results, the combination of waste materials considered for making brick samples in this study can be used as additives in lightweight eco-friendly brick production to reduce waste landfill and recycle waste. • An agricultural residue is evaluated as a pore maker in brick production. • Red mud exhibits partially a flux effect with increasing firing temperature. • Addition of wastes increases porosity and lightweight bricks are produced. • Thermal conductivity of a perforated brick model designed from obtained results is simulated. • Leaching analysis is revealed that the fired bricks are eco-friendly.

Atmospheric aerosols analysis and identification of polluting sources in the industrial city of Arak, Iran

Total suspended particulates (TSP) were collected in the industrial city of Arak, Iran, during the windy and cold seasons of 2018–2019 to investigate the air pollution sources. The associated elements were analyzed by particle‐induced X‐ray emission technique. The major elements detected in the samples were Mg, Al, Si, S, Cl, K, Ca, Ti, Mn, Fe, Co, Cu, and Zn. In this investigation, the time trend, monthly and seasonal variations, the correlation between the elemental concentrations, and the sources of air pollution were evaluated. An increase in the concentrations of Zn, Ti, and Fe was seen in winter due to temperature inversions. The highest correlation coefficients were found between soil dust key elements, Fe–Si, Ca–S, Ca–Fe, Ca–Si, and Al–Si. From the aerosols time trend concentration and the wind map direction, it was identified that there are northwesterly winds bringing desert dusts to the sampling site. The statistical positive matrix factorization model in combination with correlation coefficient and enrichment factor values were used to identify the sources of air pollution. It was deduced that the soil dusts, machining and assembling activities, industrial salts, vehicle, aluminum metallurgy, and petrochemical productions were the main contribution to the detected TSP concentration.

Permanent magnet bottom-stirred swirling flow in coaxial shallow cylindrical containers

Here, an original rotating permanent magnet (RPM) system placed coaxially with the liquid metal container is studied as an effective means of generating flow in shallow cylinders for potential application in aluminum metallurgy (e.g., for ladle stirring and metal dosing). The studied RPM system generates volume force with strong axial variation and force maximum near the radial midpoint. The numerical and experimental data show that, in the shallow cylinder case, the azimuthal velocity follows the force radial distribution. The resulting velocity maximum occurs near the radial midpoint, unlike in the traditional rotating magnetic field (RMF) stirrer systems, where the velocity maximum occurs near the outer radius. An analytical description is developed to explain the velocity radial distribution. The numerically calculated velocity distribution shows a peculiar result that the bottom-stirred liquid metal container results in peak angular momentum at the top of the container. The solution to asymptotic boundary layer equations shows that this is due to the force axial variation.

Examination of patterns in obtaining porous structures from submicron aluminum oxide powder and its mixtures

This paper proposes an economical thermal cycle of the production of ceramic articles from submicronic powders of aluminum oxide, titanium oxide, and manganese oxide. The implementation of a given cycle involves the introduction of a special aluminophosphate bond into the charge in order to reduce the temperature of firing. The optimal composition of the material for a foam-ceramic filter with the highest physical and mechanical properties has been determined; the optimal method for preparing the original charge and the baking mode have been selected. According to the results of tests under industrial conditions, the manufactured alumina filters became a decent alternative to known analogs used in aluminum metallurgy for the purification of liquid metal. The application and rational dosage of titanium dioxides, manganese, and aluminum aluminophosphate in porous ceramic compositions on an alumina base have made it possible to significantly reduce the time and, consequently, improve the productivity, of firing. The results obtained were evaluated by the level of maximum temperature in the cycle of heat treatment according to known technologies. Compared to those technologies, the developed technology ensures the growth of firing productivity when implementing the proposed solution by about 220 %. It was found that the high true density of ceramic powder requires large dispersion as the relatively large powder particles are significantly worse retained in foam films and settle. At medium (intermediate) temperatures, a large weight loss occurs at a heating rate of 10 °C/h. In this case, the decomposition progress changes in proportion to the heating speed. Changing the heating speed with temperature is the most effective technique for deparaffinization in the air. The heating time from the ambient temperature to 200 °C significantly decreases. At a certain temperature, prior to the thermal decomposition, the bond would transfer from a strongly viscous state to a liquid state

A new route for separation and recovery of Fe, Al and Ti from red mud

Red mud is one kind of by-products rejected from industrial production of alumina plant and characterized by high content of alkaline and containing many valuable metals such as iron, aluminum, titanium, etc. It is urgent to effectively utilize red mud for the sustainable development of aluminum metallurgy industry. In this paper, a new route was proposed to fully recover Fe, Al2O3 and TiO2 from the red mud, which includes three procedures, i.e. pre-reducing-smelting, alkaline leaching and acid leaching. The pre-reducing-smelting step was employed to recover iron from the mud, producing pig iron at an iron recovery of some 98.15% and slag containing 43.17%Al2O3 and 15.71%TiO2, respectively. Then, based on the thermal dynamic calculations, a modification of the slag-alkaline leaching and hydrochloric acid leaching process were conducted to obtain the stepwise recovery of Al2O3 and TiO2, respectively, from the smelting slag. Aluminum and titanium were recovered in the form of sodium aluminum solution and perovskite at a recovery of 85.85% and 95.53%, respectively. The innovative route is probably a potential way to achieve comprehensive and clean utilization of red mud.

Virtues of fluorite-case of Bou-Izourane fluorite

Fluorite minerals are among the non-metallic natural substances that have played an important role in the industry for decades. The economic importance of each of the grades of fluorite marketed meets precise chemical specifications such as its melting quality and fluor content. They also provide specific and very diverse outlets: iron and steel industry, aluminum metallurgy, plastics manufacturing, solvents, refrigerants, welding, glassmaking, cement industry, etc. In Morocco, fluorite is a very important resource because of its multiple high-grade deposits, which currently make it the 8th largest producer of metallurgical fluorite concentrate in the world with 70 kt produced per year. In the Moroccan High Atlas, the fluorite district of Bou-Izourane, located 40 km south of the city of Midelt, is estimated to be one of the most important fluorite deposits in Morocco. There are at least four violet fluorite sites in this district, the two deposits of Bou-Izourane and Bou-kharouba in the eastern part of the study area. The western part of the Bou-Izourane region hosts the two other deposits (Tabja and Bou-Imtessene). Although the Bou-Izourane fluorite is more or less colored (Violet-Lilac) with remarkable quality and perfect transparency, its uranium content, especially at the Tabja and Bou-Imtessene sites, is quite high (97.4–188.5 ppm). This property of uranium richness is an axis of research in addition to the determination of its physico-chemical characteristics, which will define the virtues and the fields of use of this fluorite. This document has been written in the hope that it will be of some use in highlighting the potential of the fluorite of the Moroccan Bou-Izourane deposit.

Synthesis and friction properties of a multifunctional diamond-containing ceramic material

Abstract The paper investigates the fundamentals of the technology of forming multifunctional composite diamond-containing materials with a ceramic matrix of an aluminum oxide. It shows the results of comparative tests of triboengineering properties of the obtained material. The developed technology for creating a billet for a diamond-containing composite ceramic material uses powder metallurgy (aluminum powder and dispersed diamonds). The paper determines optimal modes to form a billet. A sample of a composite mixture has been modified by microarc oxidation. It had a hardened layer of a ceramic matrix on its surface, and a dispersed diamond evenly enclosed in it. There is a description of features of the microarc oxidation technological process of a part from a sintered diamond-aluminum mixture compared with aluminum alloys. It is determined that the thickness of the formed ceramic layer is several times higher compared with the parts made of non-porous aluminum alloys. Moreover, the alkali concentration in the electrolyte and the relative density of a sintered billet have the greatest effect. There are two types of ceramic diamond-containing materials based on the proposed technology. They are: antifriction construction materials for sliding friction units and tool materials for abrasive processing. Triboengineering tests of materials with a small grain size of diamonds revealed their good antifriction properties even without lubricating with liquid materials. It has been established that an abrasive tool made from a material with a high grain size of diamonds has higher wear resistance and productivity compared with traditional abrasive materials.

CMOS-compatible batch processing of monolayer MoS2 MOSFETs

Thousands of high-performance 2D metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated on wafer-scale chemical vapor deposited MoS2 with fully-CMOS-compatible processes such as photolithography and aluminum metallurgy. The yield was greater than 50% in terms of effective gate control with less-than-10 V threshold voltage, even for MOSFETs having deep-submicron gate length. The large number of fabricated MOSFETs allowed statistics to be gathered and the main yield limiter to be attributed to the weak adhesion between the transferred MoS2 and the substrate. With cut-off frequencies approaching the gigahertz range, the performances of the MOSFETs were comparable to that of state-of-the-art MoS2 MOSFETs, whether the MoS2 was grown by a thin-film process or exfoliated from a bulk crystal.

Aluminum and Nickel Matrix Composites Reinforced by CNTs: Dispersion/Mixture by Ultrasonication

The main challenge in the production of metal matrix composites reinforced by carbon nanotubes (CNTs) is the development of a manufacturing process ensuring the dispersion of nanoparticles without damaging them, and the formation of a strong bond with the metallic matrix to achieve an effective load transfer, so that the maximum reinforcement effect of CNTs will be accomplished. This research focuses on the production by powder metallurgy of aluminum and nickel matrix composites reinforced by CNTs, using ultrasonication as the dispersion and mixture process. Microstructural characterization of nanocomposites was performed by optical microscopy (OM), scanning and transmission electron microscopy (SEM and TEM), electron backscattered diffraction (EBSD) and high-resolution transmission electron microscopy (HRTEM). Microstructural characterization revealed that the use of ultrasonication as the dispersion and mixture process in the production of Al/CNT and Ni/CNT nanocomposites promoted the dispersion and embedding of individual CNT in the metallic matrices. CNT clusters at grain boundary junctions were also observed. The strengthening effect of the CNTs is shown by the increase in hardness for all nanocomposites. The highest hardness values were observed for Al/CNT and Ni/CNT nanocomposites, with a 1.00 vol % CNTs.

High-speed aluminum metallurgy

High-speed aluminum metallurgy

Ceramic Objects for Dispensing Molten Aluminum Alloys

Preparation of special aluminum alloys and refractories conforming to them are considered from the point of view of physicochemical processes and aluminum metallurgy mechanisms, functional capacity of melting and casting equipment and a ceramic lining, making it possible to control casting structural and chemical parameters during their preparation. Compositions and production solutions are developed for preparing shaped refractory lining objects based on cement-free ceramic concretes.

The early years of light metals programming at TMS

The symposium “Extractive Metallurgy of Aluminum,” held in New York in 1962 under the auspices of The Metallurgical Society (TMS) of the American Institute of Mining, Metallurgical and Petroleum Engineers Inc. (AIME), was a groundbreaking event in the United States for the entire aluminum industry. As a result of two years of organizing, 55 contributors, 31 embracing the production of aluminum, freely shared results of research done within their companies or universities during this tentative opening up of communication and sharing of data and discoveries that had occurred previously only in a few conferences in Europe. The amicable interactions and success of this meeting led to the beginning of annual meetings organized by the Light Metals Committee of TMS. The consensus was emphatic that sharing non-competitive technology and discovering some of the trends in the strategies of competitors were all conducive to advancing competitiveness of the whole aluminum industry. Raising the awareness of the effectiveness of in-house R&D would enhance the innovations and creativity of all technologists. So in 1970, in Denver, the TMS Light Metals program began its series of annual symposia involving international industries, suppliers, and academia. This paper explores the inaugural TMS Light Metals symposia with the objective of commenting on how selected papers were “cutting edge” and how they influenced the electrolytic production of aluminum and inspired competitive research, improved funding, the attraction of future technologists, and “centers of excellence” for research into the Hall–Heroult process, novel processes, and advanced materials.

Development of environmentally oriented processes for obtaining the articles from aluminum powders by powder metallurgy: Report 1. Functional simulation of processes of powder metallurgy of aluminum

It is shown that, for the environmentally safe implementation of processes of powder metallurgy of aluminum, it is necessary to form highly productive technologies based on partially or completely closed cycles and new methods for preparing the starting finely dispersed aluminum powder, decreasing their dusting ability, and solving the problem of fireproofing and explosion proofing production.

Simplified PM processing of mechanically alloyed aluminium

Mechanically alloyed aluminium powder has been consolidated by a single cycle of cold pressing and sintering to produce bulk powder metallurgy (PM) aluminium parts. To facilitate the difficult consolidation, the as milled aluminium powder, eventually in the annealed condition, was mixed, previously to pressing, with a small amount of magnesium powder, as sintering aid. Both the blending of magnesium powder and the annealing treatment improves ductility and strength of consolidated samples simultaneously. Bulk samples also have a remarkable stability and performance at high temperature.

Increasing the ductility and strength of submicrometer-grained P/M aluminium

Elemental aluminium powder was attrition-milled, and then consolidated by cold pressing and sintering to produce bulk powder metallurgy (P/M) aluminium parts. To facilitate consolidation, the as-milled aluminium powder, eventually in the annealed condition, was mixed, previously to pressing, with a small amount of silicon powder, as sintering activator. Both the blending of silicon and the annealing treatment improve simultaneously ductility and strength of consolidated samples. A new strategy to increase ductility of nanostructured materials is also outlined.