Primary Aluminum Production Research Articles

The Adsorption Behavior of Moisture on Smelter Grade Alumina during Transportation and Storage—for Primary Aluminum Production

Smelter grade alumina (SGA) plays multiple roles in the Hall–Héroult process for primary aluminum production. Given its very porous nature, one major role of SGA is to adsorb toxic hydrogen fluoride (HF) in the dry scrubber. However, also because of its porous nature, SGA inevitably adsorbs ambient moisture. This paper discusses the influence of alumina properties, including pore size distribution and specific surface area, on the physical adsorption of water vapor on SGA, as well as the adsorption kinetics. The result shows that the adsorption enthalpy of moisture on SGA is in the range of 4–13 kJ/mol. The adsorption capacity increases significantly with the particle specific surface area and total pore volume. A higher adsorption temperature indicates a much faster adsorption rate but corresponds to a lower equilibrium adsorption capacity.

Analysing the chemical composition of man-made materials resultant from the production of primary aluminium in order to find cost-effective recycling techniques

Analysing the chemical composition of man-made materials resultant from the production of primary aluminium in order to find cost-effective recycling techniques

Soft Sensors in the Primary Aluminum Production Process Based on Neural Networks Using Clustering Methods.

Primary aluminum production is an uninterrupted and complex process that must operate in a closed loop, hindering possibilities for experiments to improve production. In this sense, it is important to have ways to simulate this process computationally without acting directly on the plant, since such direct intervention could be dangerous, expensive, and time-consuming. This problem is addressed in this paper by combining real data, the artificial neural network technique, and clustering methods to create soft sensors to estimate the temperature, the aluminum fluoride percentage in the electrolytic bath, and the level of metal of aluminum reduction cells (pots). An innovative strategy is used to split the entire dataset by section and lifespan of pots with automatic clustering for soft sensors. The soft sensors created by this methodology have small estimation mean squared error with high generalization power. Results demonstrate the effectiveness and feasibility of the proposed approach to soft sensors in the aluminum industry that may improve process control and save resources.

BIOMONITORING OF THE CONTENT OF FLUORINE IN WORKERS IN THE MODERN ALUMINUM MANUFACTURE

Introduction. Workers of modern aluminum plants experience long-term exposure to a complex of toxic chemical compounds, components of which are fluoride compounds. They have a chronic toxic effect on an organism. In this regard, it becomes relevant to conduct biomonitoring studies to assess the level and dynamics of excretion of fluorine in exposed workers of modern aluminum production. Material and methods. A total of 186 workers in primary aluminum production, individuals at increased professional risk (42 people) and 77 patients with established occupational diseases were examined. Results. The average fluoride - ion concentrations in the urine of aluminum production workers ranged from 1.2 ± 0.3 to 3.6 ± 0.9 mg/dm3 and were by 1.7-5.1 times higher than in the control group (0.7 ± 0.2 mg/dm3), the highest values were observed in workers of the main occupations of workshops with the technology of prebaked anodes. In workers of the high-risk group, examined in a hospital, content of fluoride ion in the urine increased by 1.1-1.4 timeswith the increase their experience of work in all experience groups (from 1.5 ± 0.2 to 2.1 ± 0.3 mg/dm3), with the exception of persons who have worked for 25 years or more (1.5 ± 0.1 mg/dm3). In workers with an established diagnosis of an occupational disease with an increase in the length of the post-exposure period there was observed a decrease in urinary fluoride ion excretion from 1.8 ± 0.1 mg/dm3 in the group with a time period up to 4 years and to 1.2±0.1 mg/dm3 in the group with 10 years or more. Conclusion. The results of studies argue a high content of fluoride ion in the urine in workers at aluminum smelters and in patients with an established diagnosis of occupational disease, which depends on the technology used, the worker’s occupation, length of service and the length of the post-contact period. This allows recommending the biomonitoring of fluoride compounds to assess occupational risks and the effectiveness of preventive and therapeutic measures.

This Thing Called Goodwill: The Reynolds Metals Company and Political Networking in Wartime America

This article examines the Reynolds Metals Company’s political networking activities in Washington, D.C., and the state capitals of the U.S. South in the 1940s and 1950s. It argues that Reynolds’ astute recruitment of senior staff from federal and state governments, its adept building of elite networks in the legislative and executive branches, its judicious espousing of key political rhetoric (antitrust, regional development, national security), as well as its nurturing of Democratic circles in the South were crucial to their attainment of competitive advantage. This saw the company rise from being a new entrant in the U.S. primary aluminum production during World War II to the second-largest national producer by 1946 and a major global player by the mid-1950s. This same political networking was critical in maintaining that advantage after World War II in the face of competition from the Aluminum Company of America and the Canadian multinational Aluminium Company of Canada. Both “wartime” (covering the period from World War II and into the Cold War) and the legacy of government intervention (from the early twentieth century until the 1960s, including the New Deal) provided a fertile context for RMC’s business strategy. The company’s success owed much to founder Richard S. Reynolds Sr.’s acumen in hiring the right people, creating or joining the right networks, having the right social capital, as well as his experiences and connections accrued from working with his uncle, the noted tobacco magnate R. J. Reynolds. The article offers insights into the nature of U.S. business–government relations.

Sustainable Primary Aluminium Production: Technology Status and Future Opportunities

Energy and greenhouse gas emission remain the major technological challenges to the aluminium production. Over the last few decades, aluminium industries have been aiming for higher production volumes through capacity creep in the existing smelters with reasonable additional investment. However, a strong focus on specific energy consumption has always been part of technology considerations, and this aspect is even more critical today from the point of view of long-term sustainability. Through research and innovations in design, control and operations of Hall–Heroult cell, modern smelters are achieving a benchmark performance as low as 13 kWh/kg of Al at commercial scale and 12 kWh/kg of Al at pilot scale. There is also significant research effort put on alternate technology platforms like drained cathode cell and inert anode. Although there are many pilot-scale demonstrations, many critical issues like operating cost and stability problems in drained cell and higher specific energy in inert anode need to be addressed for commercial consideration of these technologies. Industry 4.0 platform technologies like internet of things, cloud computing, machine learning and artificial intelligence, etc., are opening up further opportunities for benchmark performance to the modern smelters. Digital twin is such an emerging technology for predictive control and operation and will be a key driver for low-energy cells. Based on a discussion on the status of present technology, this article presents a comprehensive review of the technological progress of aluminium smelting and emerging new technology like Industry 4.0, towards reduction of energy and making aluminium production sustainable.

Scenario analysis of China's aluminum cycle reveals the coming scrap age and the end of primary aluminum boom

China has dominated the global aluminum production and consumption in the past few decades, therefore it is of particular interest to stakeholders in China and worldwide to explore whether such aluminum boom will continue or not in China. This study applies a scenario-based dynamic material flow analysis to quantify the stocks and flows along the anthropogenic aluminum cycle in China from 1950 to 2100. Potential future changes of significant parameters are explored and identified, and around 250 sets of scenario results (including all flows, stocks, and losses along the aluminum cycle in China) are obtained for the comprehensive scenario analysis. The main findings include: (1) China's primary aluminum production will peak at around 40 MMT (million metric tons) at around 2025, leading to the end of primary aluminum boom that started from the early 1990s; (2) Domestic aluminum demand will continue to increase to more than 40 MMT due to the growing accumulation of in-use stocks in meeting future societal needs; (3) China's old aluminum scrap generation will increase dramatically (around 0.8 MMT per year) soon and secondary production will account for more than 60% of aluminum production after 2050s in almost all scenarios. Thus, there will be a rapid shifting in production capacity from primary to secondary routes. In this context, the corresponding policy should focus more on the urban mining, and improvement of end-of-life management systems and sorting technologies. These scenario results also reveal key opportunities and barriers in the process. Notably, it becomes increasingly important for China's and the global aluminum industry to investigate China's future role in the global market of primary and waste aluminum products.

Vacuum Distillation-Treated Spent Potlining as an Alternative Fuel for Metallurgical Furnaces

Spent potlining (SPL) is a well-known hazardous waste from primary aluminum production, and recycling it as an alternative fuel for metallurgical furnaces is a promising application. However, because of the presence of volatile fluorides and fluoride compounds, there are significant environmental concerns and practical/engineering issues. An environmentally friendly technique involving pretreatment of SPL first cut at 700°C by vacuum distillation (VDM) is proposed herein. Using this process route, volatile and leachable fluorides (NaF, LiF, and Na3AlF6) in SPL first cut samples were successfully recycled. The distillation process was found to be beneficial for improving the fixed carbon content of the samples, and the combustion characteristics of the VDM residue were superior to those of raw untreated SPL. Such VDM residue could potentially be used in metallurgical furnaces and burners, with promising applications such as partial or full replacement of coal in pulverized coal injection (PCI) systems.

Towards the implementation of an ion-exchange system for recovery of fluoride commodity chemicals. Kinetic and dynamic studies

Spent potlining (SPL), a hazardous waste product from primary aluminium production, presents an important opportunity to recycle fluoride and conserve global fluorspar reserves. A novel strategy for treatment of the waste requires a selective fluoride-removal step from aqueous leachate. This has been demonstrated, using a Lanthanum-loaded chelating resin, in a series of kinetic and dynamic studies, with a view to industrial implementation. Kinetics could be described by the pseudo second-order model and uptake from SPL leachate was considerably higher than from equivalent NaF solutions, although observed rate constants were an order of magnitude less. Uptake of coexisting species and activation energy calculations indicated that a novel complexation interaction between La centres and aqueous aluminium hydroxyfluorides dominated the uptake process. The resin operated efficiently in column studies, with a dynamic fluoride uptake capacity of 66.7 mg g−1, calculated by the Dose-Response model, which produced the best fit to the data. The attained elution profile suggested that fluoride recovery by cryolite precipitation would be feasible, which could be recycled back into primary aluminium production or exploited as a commodity. The resin was found to have high durability in performance studies over repeated batch treatments.

Aluminium Primary Production Off-Gas Composition and Emissions: An Overview

The raw gas composition from primary aluminium production depends mostly on the process technology applied and the composition of the raw materials. At steady state, a stationary condition is established among the material sources, gas production and sinks: the gas treatment centre and escaping gases. Only a few papers discuss the off-gas composition itself; most papers deal with the gas composition from laboratory-scale experiments performed under inert conditions. In this article, an overview of the literature describing gas production from aluminium electrolysis is given. Effects of temperature and chemical equilibrium on the stationary condition are also discussed. The typical chemical composition of the raw materials is presented to evaluate their input into the gas composition, especially with respect to their impurity levels.

Elemental Carbon and Nitrogen Dioxide as Markers of Exposure to Diesel Exhaust in Selected Norwegian Industries.

Elemental carbon (EC) and nitrogen dioxide (NO2) in air as markers for diesel exhaust (DE) emission exposure were measured in selected work environments in Norway where diesel-powered engines are in use. Two hundred and ninety personal full-shift air samples were collected in primary aluminium production, underground and open-pit mining, road tunnel finishing, transport of ore, and among airport baggage handlers. EC was determined in the samples by a thermo-optical method, while NO2 was determined by ion chromatography. Highest EC air concentrations (geometric mean, GM) were found in aluminium smelters (GM = 45.5 μg m-3) followed by road tunnel finishing (GM = 37.8 μg m-3) and underground mining activities (GM = 18.9 μg m-3). Low EC air concentrations were measured for baggage handling at an international airport (GM = 2.7 μg m-3) and in an open-pit mine (GM = 1.2 μg m-3). Air concentrations of NO2 were similar in road tunnel finishing (GM = 128 μg m-3) and underground mining (GM = 108 μg m-3). Lower NO2 values were observed in open-pit mining (GM = 50 μg m-3), at the airport (GM = 37 μg m-3), and in the aluminium smelters (GM = 27 μg m-3). Highly significant (P < 0.001) positive correlations between NO2 and EC air concentrations in underground mining (r = 0.54) and road tunnel finishing (r = 0.71) indicate a common source of these pollutants. NO2 and EC were also correlated (P < 0.01) positively at the airport. However, due to the complex air chemistry and a potential contribution of various sources, the correlation between EC and NO2 cannot be regarded as unambiguous hint for a common source. The association between EC and NO2 was not of statistical significance in open-pit mining. In the aluminium smelters, EC and NO2 were negatively correlated, although not reaching statistical significance. The substantial differences in NO2/EC ratios across the investigated industries, ranging from around 0.2 in the primary aluminium production to around 25 during spring at the airport, clearly show that exposure to DE cannot be estimated based on NO2 concentrations, at least for outdoor environments. Results in the primary aluminium production suggest that the measured EC concentrations are related to DE emissions, although the NO2 concentrations were low. Further studies are required to assess the magnitude of exposure in primary aluminium production.

Impact analysis of energy efficiency measures in the electrolysis process in primary aluminium production

The Paris Agreement includes the goals of ‘holding the increase in the global average temperature to well below 2°C above pre-industrial levels’ and ‘making finance flows consistent with a pathway towards low greenhouse gas emissions’. Industrial energy efficiency will play an important role in meeting those goals as well as becoming a competitive advantage due to reduced costs for companies. The aluminium industry is energy intensive and uses fossil fuels both for energy purposes and as reaction material. Additionally, the aluminium industry uses significant amounts of electricity. The electrolysis process in the primary production of aluminium is the most energy- and carbon-intensive process within the aluminium industry. The aim of this paper is to study the effects on primary energy use, greenhouse gas emissions and costs when three energy efficiency measures are implemented in the electrolysis process. The effects on the primary energy use, greenhouse gas emissions and costs are calculated by multiplying the savings in final energy use by a primary energy factor, emissions factor and price of electricity, respectively. The results showed significant savings in primary energy demand, greenhouse gas emissions and cost from the implementation of the three measures. These results only indicate the size of the potential savings and a site-specific investigation needs to be conducted for each plant. This paper is a part of a research project conducted in close cooperation with the Swedish aluminium industry.

Analysis of microstructure in AlSi7Mg0.3 cast alloy with different content of Fe.

Abstract The use of recycled alloys brings potential energy savings, and generates less CO2 emission compared to primary aluminum production, but it is necessary to take into account their specifics properties. The properties of the secondary aluminum alloys are comparable to primary alloys, but important attention must be paid due to the higher iron content. Iron with the presence of other elements in the alloy creates intermetallic compounds which have negative influence especially on the mechanical properties. It is impossible to remove iron from melt by standard operations. Some elements eliminates iron by changing iron intermetallic phase morphology, decreasing its extent and by improving alloy properties. Therefore, the effects of different content of Iron (Fe) on the microstructure and the morphology of the intermetallic iron phases of AlSi7Mg0.3 alloy casted in to the sand molds were investigated. For influencing their morphology formation the heat treatment T6 (according standards) and addition of Manganese (Mn) were used in some bars. 2D and 3D metallographic and image analysis have been performed to measure the microstructural changes occurring at different Fe, Mn levels and heat treatment conditions. The study confirms that T6 have influence on to size of Fe-rich phases (especially in needles form), but the increasing length of Fe-needles intermetallic phases with increasing content of Fe did not by confirmed.

Entry and Exit Decisions with Switching Regime Excess Capacity

This paper examines how expected excess capacity fosters impediments to entry and incentives to exit. To examine this phenomenon, we apply the switching regime methods of Goldfeld and Quandt to a logit model using data from the U.S. aluminum industry over the period 1954 through 2010. The results show that both entry and exit decisions are statistically significantly affected by excess capacity. However, the correlation of entry and exit with capacity is more significant than with production. The evidence implies that excess capacity in the aluminum industry rises to be a substantial threat to entry only when the company produces ahead of demand growth. Excess capacity is also an impetus to exit during the later stage after primary aluminum production reverts to a declining trend.

HYGIENIC ASPECTS OF WORKING CONDITIONS IN THE MODERN PRODUCTION OF ALUMINUM

Introduction. The production of primary aluminum is one of the leading and belonging to the category of an increased health hazard for workers in the economy, which requires close attention to working conditions while modernizing production technology. Material and methods. The research methodology included a comprehensive study of working conditions and assessment of priority occupational risk factors, an in-depth study of the morphology, dispersed and component composition of dust and gas components air-suspended at different technologies of electrolysis of aluminum. Results. The leading production factors of occupational risk, degrees are fluorine-containing compounds, dust and gas-aerosol mixtures in the form of separate and assembled into agglomerates micro- and nanostructured particles of complex chemical composition (fluorine, carbon, aluminum, sodium, oxygen, silicon, iron, sulfur, chromium, nickel, etc.), unfavorable microclimate, electromagnetic field, noise, vibration, physical loads, which are related to the 3rd (harmful) class of 1 to 3 degree. Discussion. Modernization of aluminum production with the introduction of technology of pre-baked anodes allows significantly improve working conditions, reduce the admission of harmful chemical substances into the air of the working area, with the exception of hydrofluoride, the concentration of which exceeds extremely permissible levels in 1.5-3.1 times. Noteworthy is the fact of the detection of aerosols of disintegration and condensation, including particles of nanoscale range, impurities of heavy metals in the air. The consequences of the effect of such complex combination mixtures, their combined effects with other factors on the body, can have pronounced negative effects, which is important with adequate exposure analysis and personalized assessment of the health risks of workers engaged in the production of aluminum. Conclusion. Working conditions at workplaces with the technology of self-baking anodes are characterized by moderate or severe professional risk, with the technology of pre-baked anodes - mild or moderate risk, which makes the urgent problem of further improvement of aluminum production technologies, detailed analysis of personal exposures of harmful substances for a correct assessment of the health risk of workers, is relevant.

Recycling of LM25 aluminum alloy scraps

Abstract These days, a lot of metal scraps are generated by the automobile industry since the use of vehicles is increasing globally. As the production of automobile increases, the use of aluminum alloys has been increasing in automobile applications. Since the resources for the production of primary aluminum are getting scarce and the production of primary aluminum is highly expensive, production of components using secondary aluminum alloy in the form of scraps is highly essential. The present study deals with the re-melting of aluminium alloy scraps and the production of secondary aluminum alloy through a gravity die casting process. An investigation of its microstructure, chemical composition and mechanical properties such as hardness, tensile strength and an impact test have been performed and compared with the properties of primary and standard aluminum alloy. Porosity of secondary aluminum alloy is observed macroscopically. In addition a radiograph test was performed to study the internal defects of the secondary aluminum alloy.

Eco-Technological Modernization of the Irkutsk Aluminum Plant and its Impact on Carcinogenic Hazard to Shelekhov

A retrospective analysis of the modernization technology of production of primary aluminium in the Irkutsk aluminium smelter in the 55-year period of activity (1962–2017) and its implications for carcinogenic risk of polycyclic aromatic hydrocarbons and their indicator benzo(a)pyrene in the environments of the city of Shelekhov. Brief ecological and technological characteristics of the production, including the introduction of more advanced technology of baked anodes and "EcoSoderberg". The dynamics of the content of Benz(a)pyrene and its analogues in the air of the working area, the atmospheric air of the urban environment and the associated underlying surface of snow, soil and vegetation are estimated. The tendency of reduction of air pollution in comparison with depositing objects is revealed.

Recovery of Aluminum from Industrial Waste (Slag) by Melting and Electrorefining Processes

Slag of aluminum is a residue which results during the melting process of primary and secondary aluminum production. Salt slag of aluminum is hazardous solid waste according to the European Catalogue for Hazardous Wastes. Hence, recovery of aluminum not only saves the environment, but also has advantages of financial and economic returns. In this research, aluminum was recovered and purified from the industrial wastes generated as waste from both of State Company for Electrical and Electronic Industries (Baghdad/AlWaziriya) and General Company for Mechanical Industries (Babylon/-Al-Escandria). It was found that these wastes contain tiny proportions of other elements such as iron, copper, nickel, titanium, lead, and potassium. Wastes were recovered for green sustainability, saving energy and cost effectiveness. The method applied for recovering aluminum was pyro-metallurgical method by smelting and refining. X-Ray fluorescence spectroscopy and X- Ray diffraction techniques of the slag sample were used to determine the chemical analysis and phases, respectively. Melting experiments were conducted by using different types of fluxes (KAlF4, NaCl, KCl and AlCl3) at different percentages (0, 5, 10 %) and different melting temperatures (700, 750, 800oC). Design of Experiment (DOE) by Taguchi method, orthogonal array L9, was used in melting experiments. Melting efficiency of aluminum was equal to 84.7%. Electro-refining of aluminum was done by using anhydrous aluminum chloride and NaCl as ionic liquids at low temperature 100 ◦C in electro-refining method producing aluminum of 99% purity.

Recovery of Aluminum from Industrial Waste (Slag) by Melting and Electrorefining Processes

Slag of aluminum is a residue which results during the melting process of primary and secondary aluminum production. Salt slag of aluminum is hazardous solid waste according to the European Catalogue for Hazardous Wastes. Hence, recovery of aluminum not only saves the environment, but also has advantages of financial and economic returns. In this research, aluminum was recovered and purified from the industrial wastes generated as waste from both of State Company for Electrical and Electronic Industries (Baghdad/AlWaziriya) and General Company for Mechanical Industries (Babylon/-Al-Escandria). It was found that these wastes contain tiny proportions of other elements such as iron, copper, nickel, titanium, lead, and potassium. Wastes were recovered for green sustainability, saving energy and cost effectiveness. The method applied for recovering aluminum was pyro-metallurgical method by smelting and refining. X-Ray fluorescence spectroscopy and X- Ray diffraction techniques of the slag sample were used to determine the chemical analysis and phases, respectively. Melting experiments were conducted by using different types of fluxes (KAlF4, NaCl, KCl and AlCl3) at different percentages (0, 5, 10 %) and different melting temperatures (700, 750, 800oC). Design of Experiment (DOE) by Taguchi method, orthogonal array L9, was used in melting experiments. Melting efficiency of aluminum was equal to 84.7%. Electro-refining of aluminum was done by using anhydrous aluminum chloride and NaCl as ionic liquids at low temperature 100 ◦C in electro-refining method producing aluminum of 99% purity.

Recovery of Aluminum from Industrial Waste (Slag) by Melting and Electrorefining Processes

Slag of aluminum is a residue which results during the melting process of primary and secondary aluminum production. Salt slag of aluminum is hazardous solid waste according to the European Catalogue for Hazardous Wastes. Hence, recovery of aluminum not only saves the environment, but also has advantages of financial and economic returns. In this research, aluminum was recovered and purified from the industrial wastes generated as waste from both of State Company for Electrical and Electronic Industries (Baghdad/AlWaziriya) and General Company for Mechanical Industries (Babylon/-Al-Escandria). It was found that these wastes contain tiny proportions of other elements such as iron, copper, nickel, titanium, lead, and potassium. Wastes were recovered for green sustainability, saving energy and cost effectiveness. The method applied for recovering aluminum was pyro-metallurgical method by smelting and refining. X-Ray fluorescence spectroscopy and X- Ray diffraction techniques of the slag sample were used to determine the chemical analysis and phases, respectively. Melting experiments were conducted by using different types of fluxes (KAlF4, NaCl, KCl and AlCl3) at different percentages (0, 5, 10 %) and different melting temperatures (700, 750, 800oC). Design of Experiment (DOE) by Taguchi method, orthogonal array L9, was used in melting experiments. Melting efficiency of aluminum was equal to 84.7%. Electro-refining of aluminum was done by using anhydrous aluminum chloride and NaCl as ionic liquids at low temperature 100 ◦C in electro-refining method producing aluminum of 99% purity.