Aluminum Scrap Research Articles

Synthesis of nanocrystalline MgO/MgAl2O4 spinel powders from industrial wastes

This article reports a simple and cost-effective method to prepare ultrafine nanocrystalline MgO/MgAl2O4 spinel (M-MA) powders from industrial wastes arising from aluminium and magnesium scraps. M-MA precursor powders were calcined at different temperatures (650, 750, 850, 950, 1300–1500 °C). The calcined powders were characterized by XRD, FT-IR, DTA, FESEM, and HR-TEM. In particular, ultrafine MgO/MgAl2O3 powder was formed at a temperature of 650 °C with crystallite size of 4.8 nm and 7 nm, respectively, as determined by XRD. Optical properties of the M-MA spinel powders revealed that the optical reflectance is highly dependent on the calcination temperature. A simple and cost-effective method to obtain ultrafine MgO/MgAl2O4 nanocrystalline powders with expected unique properties was established. These synthesized spinel powders is a highly promised feedstock for refractory, ceramic and environmental applications.

Processing of Al-Fe Scraps by Powder Metallurgy

Iron has a low solubility in aluminium solid solution even at elevated temperatures and forms brittle intermetallic phases with needle-like or platelets-like morphology when it is produced by conventional casting technologies. These phases have a detrimental effect on mechanical properties. Therefore with increasing significance of recycling and also amount of aluminium scrap that needs to be recycled, it is necessary to find a promising ways of processing such waste materials. Powder metalurgy leads to intensive microstructural refinement, increases solid solubility of alloying elements and overall to improvement of mechanical properties. Hence, it belongs to promising alternatives for proccesing aluminium materials with increased amount of iron. Aluminium alloy with 17 wt. % iron was prepared by centrifugal atomization and consolidated by spark plasma sintering followed by hot extrusion. The microstructure and phase composition of compact samples as well as mechanical properties were studied. Fine microstructure has been achieved by centrifugal atomization and consolidation by spark plasma sintering in combination with hot extrusion. Compression strength was 565 MPa with remarkable ductility reaching almost 35 %.

A New Trend of Physical Concentration in Resources Recycling

Physical separation is one of the key technologies in the field of resources recycling for concentrating targeted component(s) and could create an environment friendly recycling process because of their relatively low energy consumption and low cost required. Physical separation process involves two kinds of stages, one is comminution for achieving the liberation of targeted component(s) and the other is real separation of target component(s) from the others. Recently a variety of smart comminution processes, involving mechanical and electrical disintegration as well as the pre-treatment, is developed for aiming selective breakage of phase boundaries of the solid materials to be recycled. The paper indicated several examples of such processes, (1) selective mechanical comminution for effective utilization of aluminum dross, (2) two-stage comminution for recovering minor rare metals from electronic appliances, and (3) concentration of platinum group metals from spent automobile catalyst. The paper also mentioned a sensor based sorting (SBS) process by combining several sensing systems, XRT and XRF, to achieve a horizontal recycling of scrap aluminum.

Circular economy: To be or not to be in a closed product loop? A Life Cycle Assessment of aluminium cans with inclusion of alloying elements

Packaging, representing the second largest source of aluminium scrap at global level, deserves a key role in the transition towards the circular economy. Life Cycle Assessment (LCA) of aluminium products has been typically based on one life cycle considering pure aluminium flows and neglecting the presence of alloying elements and impurities. However, this simplification undermines the potentials of using LCA to quantify the environmental performances of products in multiple loops, as required in the circular economy. This study aims to investigate the effects of including the actual alloy composition in the LCA of aluminium can production and recycling, in order to understand whether a can-to-can (i.e. closed product loop) recycling should be promoted or not. Mass balance of the main alloying elements (Mn, Si, Cu, Fe) was carried out at increasing levels of recycling rate, corresponding to a temporal interval of five years. Different aluminium packaging scrap sources were considered: mixed packaging aluminium scrap and used beverage can scrap. The outcomes of the mass balance were used to quantify the amount of Mn and primary Al that needs to be reintegrated in each scenario according to the recycling rate and this information was further used to perform an LCA of 30 loops of aluminium can production and recycling, based on the actual alloy composition. The LCA revealed that the closed product loop option (considering used beverage can scrap) has lower climate change impacts over the other recycling scenario using mixed Al packaging scrap. The main recommendation from an LCA methodological point of view is to include the idea of multiple co-functions in the functional unit definition. To further improve the environmental performances of the aluminium beverage can sector towards circular economy implementation the key actions are: to reduce the weight of the lid, to develop methods to separate the body and lid at the point of collection, and to investigate the potentials of a closed supply chain loop for aluminium cans in terms of combined environmental and economic value creation.

Influence of Salt Quantity on Recovery Yield of Heterogeneous Aluminium Scrap

The influence of the salt quantity on the recovery yield of aluminium scrap was studied considering an heterogeneous charge. The analysed heterogeneous charge was composed by different types of scrap such as turning, shredded materials and dross. The amount of salt was related to the scrap quality using the salt factor, which is defined as the ratio between the non-aluminium content in the scrap and the quantity of salt required. Two levels of salt factor were considered, 1.2 and 1.8. The analysis of variance was then implemented to verify the influence of the salt quantity on the recovery yield. The results were statistically confirmed using the Anderson-Darling test, the Dixon’s outliers test and the coefficient of variance. An increment of the recovery yield from 95% to 97% was revealed by increasing the salt factor from 1.2 to 1.8.

Development and Evolution of Aluminum Industry in China Based on Aluminum Flow Analysis

AbstractThe whole process of aluminum cycle consists of four stages: Production of alumina and primary aluminum, fabrication and manufacture of aluminum products, use of aluminum final products, and recycling of obsolete aluminum products. Aluminum cycle in China in 2011 was analyzed using alumium flow diagram, and the following indices were obtained: The resource self-support ratio of alumina, aluminum and the whole aluminum industry were 53.18%, 95.58% and 54.85%, respectively; self-produced and net imported aluminum scrap use ratios of the aluminum industry were 4.68% and 7.98%, respectively. Aluminum cycles and aluminum flow indices in China of the year 1990, 1995, 2000, 2005 and 2008–2010 were also analyzed. It was found that from 1990 to 2011, imported Al-containing resources increased and imported bauxite has increased significantly since 2005. Resources self-support ratio of aluminum industry changed gradually from fully self-support to depencdent on the imports of raw materials. Self-produced auminum scrap use ratio presented downtrend basically and the imported aluminum scrap use ratio was greater than self-produced aluminum scrap use ratio after 1995.

Aluminium scrap melting under different liquid aluminium flow conditions: part-I: single phase flow

The melting characteristics of aluminium (Al) scrap were studied in a pilot-scale revolving liquid metal tank (RLMT) which sits in a resistance furnace. Commercially pure Al of about 39 kg was melted in the RLMT. Experiments were carried out in a stagnant and in a revolving Al bath at different liquid metal temperatures and speeds. Cylindrical Al 6061 alloy samples were used in this experimental work. Their melting time inside the Al bath was recorded with a specially designed electrical circuit. Upon immersion of a cold cylindrical sample into liquid Al, a shell solidifies around the specimen and subsequently melts back. The time during which the shell exists around the cylinder is called shell period. The free melting period commences when the shell period ends. The thermal contact resistance (TCR) at the Al shell/cylinder interface affects how long the shell lasts. A methodology was developed to estimate this TCR. The convective heat flux from the Al bath to the cylindrical specimen influences the shell and free melting periods, and is a function of liquid Al temperature and speed. The Part I of this research work presents a baseline of Al melting measurements under single phase flow conditions, that will be compared against two phase flow conditions in Part II of this research.On a étudié les caractéristiques de fusion de rebut d’aluminium (Al) à l’échelle pilote dans une citerne rotative de métal liquide (RLMT), située dans un four à résistance. On a fait fondre dans la RLMT environ 39 kg d’Al commercialement pur. On a effectué les expériences dans un bain stagnant ou dans un bain rotatif d’Al à diverses températures et à diverses vitesses du métal liquide. Dans ce travail expérimental, on a utilisé des échantillons cylindriques d’alliage d’Al 6061. On a enregistré leur temps de fusion dans le bain d’Al au moyen d’un circuit électrique spécialement conçu. Au moment de l’immersion d’un échantillon cylindrique froid dans l’Al liquide, une coquille se solidifie autour de l’échantillon et subséquemment, fond à son tour. La période durant laquelle la coquille existe autour du cylindre s'appelle la période de coquille. La période de fonte libre commence quand la période de coquille se termine. La résistance du contact thermique à l’interface coquille et cylindre d’Al affecte la durée de vie de la coquille. On a développé une méthodologie pour estimer cette résistance du contact thermique. Le flux de chaleur par convection du bain d’Al à l’échantillon cylindrique influence les périodes de coquille et de fonte libre, et il est une fonction de la température et de la vitesse de l’Al liquide. La première partie de ce travail de recherche présente une ligne de base des mesures de fusion de l’Al sous des conditions d’écoulement monophasé, qui sera comparée à des conditions d’écoulement biphasé dans la deuxième partie.

Aluminium scrap melting under different liquid aluminium flow conditions: part-II: two phase flow

This experimental research work deals with aluminium (Al) alloy melting in an Al bath. In this liquid metal, nitrogen gas was introduced at specific locations and at different gas flow rates. The samples employed, along with their position in the liquid Al, and the procedure for melting detection, were identical with the ones utilised in Part I. The introduction of gas into liquid Al has different effects on the melting time of the immersed Al 6061 alloy cylinder. For the range of gas flow rates examined, the addition of gas into a stagnant Al bath (i.e. natural convection conditions) produces insignificant changes in melting time. However, when the liquid Al is moving (i.e. forced convection conditions), the gas addition leads to a sizeable reduction in melting time. The melting time reduction ratio is introduced as a way to compare the melting under single and two phase flow liquid Al conditions. It is found that this ratio is affected by the nozzle position and also by the gas flow rate. The concept of an equivalent single phase velocity is also introduced, and defines the single phase velocity of liquid Al which results in the same melting time of the cylinder as under two phase flow conditions. It is found that the equivalent single phase velocity is influenced by both the gas flow rate and the nozzle position. The parameter which most likely contributes to the acceleration of the melting rate in two phase flow is the turbulence intensity, which is expected to increase due to the nitrogen gas injection.

Cancer risk among workers of a secondary aluminium smelter.

Cancer risk in secondary aluminium production is not well described. Workers in this industry are exposed to potentially carcinogenic agents from secondary smelters that reprocess aluminium scrap. To evaluate cancer risk in workers in a secondary aluminium plant in Spain. Retrospective cohort study of male workers employed at an aluminium secondary smelter (1960-92). Exposure histories and vital status through 2011 were obtained through personal interviews and hospital records, respectively. Standardized mortality (SMRs) and incidence ratios (SIRs) were calculated. The study group consisted of 98 workers. We found increased incidence and mortality from bladder cancer [SIR = 2.85, 95% confidence interval (CI) 1.23-5.62; SMR = 5.90, 95% CI 1.58-15.11]. Increased incidence was also observed for prostate cancer and all other cancers but neither were statistically significant. No increased risk was observed for lung cancer. Results of this study suggest that work at secondary aluminium smelters is associated with bladder cancer risk. Identification of occupational carcinogens in this industry is needed.

Pengaruh Tegangan dan Waktu Nickel-Chrome Plating terhadap Kekasaran Permukaan pada Hasil Produk Pengecoran Aluminium Scrap

Aluminum was widely used in the industry because of its light weight, along with the increasing need for spare parts which has spurred the foundry industry locally to utilize the aluminum alloy scrap material to be melted again (re-melting). Although, nowadays many local industries remelting wheels scrap, but the resulting product had a highly roughness of material surface, so it is necessary to finish the process with surface treatment method of electroplating using nickel-chrome. This study aims to determine the effect of voltage and time of nickel-chrome plating on aluminum scrap casting products. During the nickel-chrome plating process, the voltage of 5, 7, 5, 9 volts and the time of 5, 10, 15 seconds were used. The results shown that the aluminum scrap of nickel-chrome plating roughness decreased along with the increasing of electrical voltage and time. The 5 volts of electrical voltage resulted in decrease of surface roughness by 13,53 – 37,2 %, 7,5 volts resulted 2,7% - 55,91 %, and 9 volts resulted 24,9% - 49,71 %. Furthermore, 5 seconds of surface coating time produced 19,14% - 42,9% of the decreasing of surface roughness, 10 seconds produced 8,9% - 50,4 % and 15 seconds produced 47,1% - 57,4 %. These results shown that nickel-chrome plating with fluctuations in voltage and time had an effect on the surface roughness.

Pengaruh Tegangan Listrik Dan Waktu Pada Krom Plating Terhadap Keausan Pada Hasil Produk Pengecoran Aluminium Scrap

Currently use of materials to manufacture spare parts of motorcycle has progress among others is aluminum alloy. Alloy properties aluminum is lenient, be formed, easy to work with machines, thermal and electrical conductivity is high, and is not magnetic. The purpose of this study was to determine the effect of electric voltage and time on chrome plating toward wear product casting aluminum scrap. For the materials used casting process is a motor vehicle wheels made of aluminum material with gravity casting process. The sample size of 30 mm x 30 mm x 10 mm. Subsequently, the samples were chrome plating is used with a power supply voltage, 5, 7.5 and 9 volts, and a long period of 5, 10 and 15 seconds. Tests after the wear of the samples coated with chrome testing using Ogoshi wear and so also the data analysis is performed. Show on basis of the test results, a decrease in the value of chrome wear with increasing electrical voltage and time. Values wear coating chrome plating at time 5, 10 and 15 seconds with voltage 5 volt is 7.859-07 mm2/kg, 4,366E-07 mm2/kg, 2.490E-07 mm2/kg, voltage 7.5 volt in the amount of 4.882E-07 mm2/kg, 2.525E-07 mm2/kg, 2.248E-07 mm2/kg, and voltage 9 volt in the amount of 3.394E-07 mm2/kg, 2.213E-07 mm2/kg, 2.250E-07 mm2/kg. The highest wear value at 5 volts with 5 seconds and the lowest wear value at 9 volts 15 seconds

Pengaruh Variasi Tegangan Dan Waktu Terhadap Kekerasan Lapisan Nikel Dengan Metode Electroplating Pada Coran Aluminium Scrap

Aluminum is widely used in the industry for its light weight, corrosion resistance and good heat conductivity and high electrical. Violence is not so high and a less attractive appearance needs to be fixed, one of which with a coat of aluminum with a Nickel electroplating process. This research aims to know the influence of voltage and time of Nickel plating on aluminum scrap casting. The specimen made from castings of optional with a size of 30 x 30 x 10 mm. Nickel coated aluminum with electroplating process with a voltage of 3, 4.5 and 6 volt. With the variation of time coating 5, 10 and 15 minutes. Once coated, micro hardness testing done by the method of testing the Vickers with a load of 10 gr and detained 10 s. test results indicate the presence of nickel plating hardness values increase with increasing voltage and time. Electric voltage 3 volts of 10.4%-15.9%, 4.5 volt voltage of 14.3%-4.62%, and 6-volt voltage of 24.8%-84.2%

INVESTIGATIONS ON OPERATION OF ROTARY TILTING FURNACES

Rotary tilting furnace (RTF) is a new type of fuel furnaces, that provide the most efficient heating and recycling of polydisperse materials. The paper describes results of the investigations on thermal processes in the RTF, movement of materials and non-isothermal gas flow during kiln rotary process. The investigations have been carried out while using physical and computer simulations and under actual operating conditions applying the pilot plant. Results of the research have served as a basis for development of recommendations on the RTF calculations and designing and they have been also used for constructional design of a rotary tilting furnace for heating and melting of cast iron chips, reduction smelting of steel mill scale, melting of aluminum scrap, melting of lead from battery scrap. These furnaces have a high thermal efficiency (~50 %), technological flexibility, high productivity and profitability. Proven technical solutions for recycling of ferrous and non-ferrous metals develop the use of RTF in the foundry and metallurgical industry as the main technological unit for creation of cost-effective small-tonnage recycling of metal waste generated at the plants. The research results open prospects for organization of its own production for high-quality charging material in Belarus in lieu of imported primary metal. The proposed technology makes it possible to solve environmental challenge pertaining to liquidation of multi-tonnage heaps of metal-containing wastes.

Application Integrated Fuzzy TOPSIS based on LCA Results and the Nearest Weighted Approximation of FNs for Industrial Waste Management-Aluminum Industry: Arak-Iran

Background/Objectives: Aluminum dross as waste is always a problematic issue. The aim of this study is to apply a systematic method for the Aluminum waste management system selection problem in environment management. Methods/Statistical Analysis: In this study, a methodology extended fuzzy TOPSIS and based on LCA is applied by using the nearest weighted interval approximations. The functional unit includes aluminum dross and aluminum scrap, which are defined as 1000 kg. The model is confirmed in the case of aluminum waste management in the city of Arak. The scenarios are ranked based on their closeness coefficient to the ideal solution. Results: Five scenarios, in a step-wise manner were surveyed. Based on study results and particularly the closeness coefficients, Scenario S4 was assigned as the most preferred choice with a weight of 0.723514. Also the Scenario S1with a value of 0.448137, Scenario S5 with a value of 0.354226, Scenario S2 with a value of 0.314215 and Scenario S3 with a value of 0.204909 were ranked from second to fifth respectively. The results of the present study illustrated that the procedure is simple in calculations and set priorities. It is very appropriate for solving MCDM problems. Conclusion/Application: From the application perspective, this research will provide a valuable insight for managers to attempt to improve the environmental, social and economic condition all together at the same time.

Recycling without Melting: An Alternative Approach to Aluminum Scrap Recovery

Method of scrap recovery by hot extrusion in a contrast to traditional aluminum recycling process distinguishes itself with a low energy consumption and high recovery efficiency. Additionally, this type of recycling allows to recover materials even from highly fragmented forms of metal like chips, foils or filings by omitting melting procedure. In the present study results of 413.0 aluminum chips plastic consolidation will be presented. Chips after machining process were used as a charge material for the entire recycling process. In order to determined the best emulsion elimination method, three separate processes such as centrifugation, annealing and pressing were carried out. In result dry, wet and cleaned chips in a form of cylindrical billets were hot extruded into longitudinal square cross-section profiles. Mechanical properties were examined by uniaxial tensile tests while microstructure observations were performed by means of scanning electron microscopy. It has been showed that emulsion elimination by annealing gives the best results while at the same time all extruded materials revealed no significant differences in mechanical properties.

Nanocrystalline Ni3Al-based alloys obtained by recycling of aluminium scraps via mechanical alloying and consolidation

Bulk nanocrystalline Ni3Al-based alloys were produced by ball milling of powdered aluminium scrap alloys (two silumines with chemical compositions: Al87.5Si7.8Cu2.1Fe0.7Zn1.4Mn0.4Mg0.1 (R1 scrap) and Al88.4Si5,7Cu3,9Fe0,9Zn0,6Mn0.5 (R2 scrap)) with addition of Ni powder and subsequent hot-pressing consolidation. The final products of mechanical alloying were consolidated at 1000°C for 180s under the pressure of 7.7GPa. The powders and the compacted samples were examined by XRD method. The results obtained show that during the milling supersaturated solid solutions Ni(Al,Si…) are formed and during the consolidation the disordered solid solutions transform into ordered nanocrystalline Ni3Al intermetallic based phases with a mean crystallite size of ∼30nm. The microhardness of the produced Ni3Al-based alloys is 955 for R1 process and 928 HV0.1 for R2 process respectively. The density of the pellets is nearly 100% of theoretical value for the Ni3Al intermetallic phase and the open porosity of the compacts is negligibly small.

The Integrated Fuzzy AHP and Goal Programing Model Based on LCA Results for Industrial Waste Management by Using the Nearest Weighted Approximation of FN: Aluminum Industry in Arak, Iran

The worldwide recycled aluminum generation is increasing quickly thanks to the environmental considerations and continuous growing of use demands. Aluminum dross recycling, as the secondary aluminum process, has been always considered as a problematic issue in the world. The aim of this work is to propose a methodical and easy procedure for the proposed system selection as the MCDM problem. Here, an evaluation method, integrated FAHP, is presented to evaluate aluminum waste management systems. Therefore, we drive weights of each pair comparison matrix by the use of the goal programming (GP) model. The functional unit includes aluminum dross and aluminum scrap, which is defined as 1000 kilograms. The model is confirmed in the case of aluminum waste management in Arak. For the proposed integrated fuzzy AHP model, five alternatives are investigated. The results showed that, according to the selected attributes, the best waste management alternative is the one involving the primary aluminum ingot 99.5% including 200 kg and the secondary aluminum 98% (scrap) including 800 kg, and beneficiation activities are implemented, duplicate aluminum dross is recycled in the plant, and finally it is landfilled.

The Modification of β-Al<sub>5</sub>FeSi Phase in Al-Si-Mg-Fe Alloys by Utilizing Recycled Beverage Can Body in Casting Process

The acicular iron intermetallic compound, β-Al5FeSi, is often quoted as disadvantages in aluminum based alloy ingots because of its brittleness. This undeniable phase, however, is found to show less effects on the ingots properties if trace manganese is added. The modified round ended and Chinese script-like structure showed significant higher ductility. The present work reports results of prospective experiments designed for obtaining shape modification of the iron intermetallic compound exclusively from readily available scrap aluminum cans as a source of manganese. A356 aluminum alloy with 1 wt.% iron and 10 wt. % manganese calculated from recycled aluminum can was melted in a laboratory furnace. The molten metal was soaked at 800°C for different aging times ranging from 15, 60 to 120 minutes before undergoing the conventional casting process. The produced ingots were characterized concerning their microstructures, hardness and final composition, which allows estimating the proper aging time for the microstructure improvement. It was observed that the 60 minute-aging time yielded the best modification of 14 micron round ended needle morphology. However, the longer aging time resulted in lower hardness as the result of the obtained Al15(MnFe)3Si2 as a majority phase.

Formation and emission of brominated dioxins and furans during secondary aluminum smelting processes

Secondary aluminum smelting (SAl) processes have previously been found to be important sources of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs). It is crucial that the key factors that influence the formation and emission of PBDD/Fs are identified to allow techniques for decreasing PBDD/F emissions during SAl processes to be developed. In this study, stack gas samples were collected from four typical secondary aluminum smelters that used different raw materials, and the samples were analyzed to allow differences between PBDD/F emissions from different SAl plants to be assessed. The composition of the raw materials was found to be one of the key factors influencing the amounts of PBDD/Fs emitted. The PBDD/F emission factors (per tonne of aluminum produced) for the plants using 100% (Plant1), 80% (Plant2), and 50% (Plant3) dirty aluminum scrap in the raw material feed were 180, 86, and 14 μg t(-1), respectively. The amounts of PBDD/Fs emitted at different stages of the smelting process (feeding-fusion, refining, and casting) were compared, and the feeding-fusion stage was found to be the main stage in which PBDD/Fs were formed and emitted. Effective aluminum scrap pretreatments could significantly decrease PBDD/F emissions. Much higher polybrominated dibenzofuran concentrations than polybrominated dibenzo-p-dioxin concentrations were found throughout the SAl process. The more-brominated congeners (including octabromodibenzo-p-dioxin, octabromodibenzofuran, heptabromodibenzo-p-dioxins, and heptabromodibenzofurans) were the dominant contributors to the total PBDD/F concentrations. The results could help in the development of techniques and strategies for controlling PBDD/F emissions during metallurgical processes.

Production of Magnesium and Aluminum-Magnesium Alloys from Recycled Secondary Aluminum Scrap Melts

An experimental proof of concept was demonstrated for a patent1 and trademark2-pending RE-12™ process for extracting a desired amount of Mg from recycled scrap secondary Al melts. Mg was extracted by electrorefining producing Mg product suitable as Mg alloying hardener additive to primary grade Al alloys. This efficient electrorefining process operates at high current efficiency, high Mg recovery and low energy consumption. Mg electrorefining product can meet all the impurity specifications with subsequent melt treatment for removing alkali contaminants. This economical and environmentally friendly chlorine-free RE-12™ process could be disruptive and transformational for the Mg production industry by enabling the recycling of 30,000 tonnes of primary-quality Mg annually.