Aluminum Production Research Articles

Bioprospects of Tree Species in Bioremediation of Bauxite Residue

Red mud or bauxite residue is a highly alkaline toxic by-product that is generated during the production of aluminum by Bayer’s process. Around 1.5 tons of bauxite residues are produced for generating 1 ton of alumina. The toxicity of bauxite residue is a major catastrophe due to its disposal management as it limits the growth of plant species because of high alkalinity and salinity. In the present study, bioprospects carried through the cyanobacterial strains (viz. Phormidium and Oscillatoria) with the planting of tree species have potentially shown successful outputs on the physical and chemical attributes of bauxite residue. The cyanobacterial strains were combined along with the microbial cultures of VAM (vesicular arbuscular mycorrhiza) and PSB (phosphate solubilizing bacteria) to enhance root length, leaf area, fresh and dry weight of shoot and root, plant height, and chlorophyll content. The inoculated seeds of a few plant species namely, Siamese cassia, Acacia auriculiformis A. Cunn. ex. Benth., Dalbergia sissoo Roxb. Ex DC., Pithecellobium dulce (Roxb.)., and Prosopis juliflora var. juliflora were raised to study the effect of bioremediation of bauxite residue for revegetation. Further, we also found that S. cassia, A. auriculiformis, D. sissoo, P. dulce, and P. juliflora var. juliflora thrived well on the amended bauxite residue with other useful inoculums.

Scoping Review of Employer-Led Research Using Employee Health Claims Data.

Employers may evaluate employee claims data for various reasons, including assessment of medical insurance and wellness plan efficacy, monitoring employee health trends, and identifying focus areas for wellness measures. The objective of this scoping review (ScR) is to describe the available literature reporting the use, applications, and outcomes of employee health claims data by self-insured employers. The ScR was conducted in a stepwise manner using an established framework: identifying the research question, identifying and selecting relevant studies, charting the data, and collating and reporting results. Literature searches were conducted in PubMed and Embase. Studies of self-insured employee populations that were conducted by the employer/s through May 2022 were identified using predefined criteria. Forty-one studies were included. The majority (90%) were cohort study designs; most employers (51%) were in industries such as aluminum production and health insurance providers. Twenty-four (59%) studies supplemented claims data with other sources such as human resource data to evaluate programs and/or health outcomes. A range of exposures (eg, chronic conditions, wellness program participation) and outcomes (eg, rates or costs of conditions, program effectiveness) were considered. Among the 25 studies that reported on patient confidentiality and privacy, 68% indicated institutional review board approval and 48% reported use of deidentified data. Many self-insured employers have used employee health claims data to gain insights into their employees' needs and health care utilization. These data can be used to identify potential improvements for wellness and other targeted programs to improve employee health and decrease absenteeism.

Properties and characterization of red mud modified by hydrochloric, sulfuric, and nitric acid for the catalytic oxidation of toluene

In this paper, red mud (RM), a solid waste with high alkalinity generated by the alumina production industry, was modified using three different acids. The catalytic efficiency of HNO3-MRM was the best, and the T10, T50, and T90 were 280 ℃, 325 ℃, and 361 ℃, respectively. The CO2 selectivity of HNO3-MRM was better than those of HCl-MRM and H2SO4-MRM. Further, the HNO3-MRM catalyst maintained high stability at 420 ℃. This good catalytic performance of HNO3-MRM is related to its high specific surface area, Fe3+ content, surface adsorbed oxygen content, and surface acidic sites. The reaction rate linearly increases with the number of surface acidic sites on the catalyst, indicating that surface acidity is an important factor affecting the catalytic activity of toluene. H2SO4 solution forms calcium sulfate with Ca2+ in the RM, resulting in a lower catalytic activity for H2SO4-MRM. Fe2O3, Al2O3, and SiO2 were the main components of HNO3-MRM. Fe2O3 was the active component of the catalyst, which played the role of the catalytic oxidation of toluene. Al2O3 and SiO2 were used as catalyst carriers. Moreover, the catalytic mechanism of toluene oxidation over the HNO3-MRM catalyst was studied. The catalytic oxidation of toluene on HNO3-MRM catalysts may have two simultaneous reaction paths. The first reaction path would be toluene → species benzyl→ benzaldehyde→ benzoic acid→ heptaldehyde→ CO2 and H2O. The second reaction path would be toluene → benzene →phenol → maleic acid →CO2 and H2O.

Recyclability of aluminium piston alloy

One of the most recycled and recyclable materials now in use is aluminium. Frequently, aluminium cans, automobile components, and window frames are recycled back into itself. A vital component of the contemporary aluminium industry is recycling. Recycled aluminium production uses only around 5% of the energy required to produce new aluminium, resulting in lower carbon emissions and cost savings for both corporations and end users. As a result, today's use of roughly 75% of all aluminum created throughout history. Recycling rates for aluminium exceed 90% in the majority of industrial sectors, including the construction and automobile industries. Every year, the United States saves more than 90 million barrels of oil equivalent through industry recycling. Capability to re-melting aluminium alloys scrap without losing its alloying elements and finding optimum pouring temperature are the purpose of this paper, and the results will determine the possibility of reusing piston alloy to make components similar to those they were recycled from. Automotive cast aluminium scrap obtained from pistons were used as experimental specimens, which were melted via an electrical furnace then poured at four different temperatures, namely 680, 720, 760, and 800 °C into a strip fluidity steel mould. The chemical composition of the four specimens were examined using spark emission spectrometer and the length of melted metal that flowed through the mould strips was measured as well to determine fluidity. Also, an optical microscope was used to detect microstructure defects. The chemical composition ratios of alloying elements before and after recycling showed that the resulting alloys could be closely equivalent to the commercial alloy that was originally used to make the components. In addition, the higher the pouring temperature the greater the casting fluidity. Generally, the consumed aluminium piston alloy can be re-melted and used to produce many parts.

Study of glutathione-S-transferase (GST) T1 and M1 genes in aluminum industry workers with comorbid cardiovascular pathology

Introduction. Employees of the main professions of aluminum production have a high level of professional and production-related pathology, primarily diseases of the circulatory system associated with the long-term influence of vasotoxic factors on the body. The pathogenetic course of angiopathies does not proceed in isolation, it is predetermined by chronic fluoride intoxication and hereditary component. The establishment of associations determined on the basis of studying the polymorphism of glutathione-S-transferase genes with the risk of developing comorbid cardiovascular pathology makes it possible to use genetic analysis in its early diagnosis.
 The study aims to explore the polymorphism of GST genes in aluminum industry workers with comorbid cardiovascular pathology.
 Materials and methods. The authors have carried out the study using clinical and molecular genetic diagnostic methods in workers of the main professions engaged in the production of aluminum, with chronic occupational intoxication with fluorine compounds and persons with individual signs of fluoride exposure to the skeleton (comparison group). By detecting extended deletions in the loci of the GSTT1 and GSTM1 genes, the researchers have assessed the association of the studied genotypes with the risk of chronic intoxication and atherosclerosis.
 Results. In the cohort of patients (36.58%) and in the comparison group (16.98%), the authors have revealed a combined form of cardiomyopathy complicated by coronary atherosclerosis, coronary heart disease. Also, scientists have established significant differences in the frequency distribution of genotypes of GST genes. Homozygous polymorphism GSTT1 0/0 is a risk factor for the development of occupational pathology against the background of the predominance of the normal genotype GSTM1+. Predictors (GSTT1 0/0, GSTM1 0/0) of the risk of atherosclerosis associated with hypertension in persons with chronic fluoride intoxication were determined.
 Conclusion. The association of GST genes with the development of comorbid cardiovascular pathology was determined in the structure of professional and production-related pathology in aluminum industry workers.
 Ethics. We have conducted the study of employees at the aluminum plant on a voluntary basis with the written consent of the examined persons on the basis of a specialized clinic of the Research Institute of Complex Problems of Hygiene and Occupational Diseases in accordance with the Ethical principles of conducting scientific and medical research with human participation ("Rules of Clinical Practice in the Russian Federation", Order of the Ministry of Health of the Russian Federation No. 266, 2003; Helsinki Declaration of the World Medical Association "Ethical principles of conducting scientific medical research with human participation", 2013).

Highly efficient separation of titanium minerals from a modified bauxite residue through direct reduction: A comparison study

Bauxite residue, which is a solid waste generated during the production of alumina, contains significant amounts of iron (Fe) and titanium (Ti) resources. The large-scale utilization of bauxite residue has become an urgent concern from both an environmental and resource perspective. In this study, a calculation of phase diagram (Calphad) was conducted to analyze the changes in mineral phases during the direct reduction process of both the current and reductive Bayer bauxite residue. Additionally, a comparison experiment was performed to investigate the enrichment and separation characteristics of iron and titanium minerals. The results indicated that during the carbon thermal reduction process, titanium existed as CaTiO3 and Na-Al-Si-Ti molten phase slag in the current and reductive Bayer bauxite residue, respectively. Furthermore, NaFeO2 was observed in the latter slag phase, which facilitated the migration and reduction of iron-containing minerals. The reductive Bayer bauxite residue was carbon thermal reduced for 1 h at a temperature of 1200 °C, with the addition of 7.5% Na2CO3. Following grinding and separation under a magnetic field strength of 0.08 T, the iron grade of the concentrate, iron recovery, and TiO2 grade in the tailing increased to 95.30%, 98.40%, and 50.50%, respectively. This was in comparison to the bauxite residue from current Bayer digestion, which showed values of 78.90%, 87.18%, and 14.87% under the same conditions. The findings of this work contribute to the potential utilization of iron and titanium present in bauxite residue from a modified Bayer digestion process.

Improvement of combustion performance with novel vortex generators in the powder-fueled ramjets

Combustion performance of powder-fueled ramjets depends mainly on the combustor configurations. In this study, three combustors with various vortex generators are put forward firstly in powder-fueled ramjets. The comparison between three novel and the basic configurations is conducted and analyzed by transient numerical simulation. It can be proved that three configurations with various vortex generators have positive effects on the gas-particle phases flow field, mass fractions of products and combustion efficiency. The scheme of tapped vortex generator has best gas-particle flow temperature distribution and most mass fraction of products, meaning more transfer and consumption of powdered fuel. The oxygen content in the scheme of tapped vortex generator, being only 60% of that in basic scheme, also proves the conclusion. Moreover, this configuration also has most mass flow rate of Aluminum gas, products and most particles resided in the combustor, which is 2.25 times than the basic combustor.

Developing a Comprehensive Mathematical Model for Aluminium Production in a Soderberg Electrolyser

The technological process of aluminium electrolysis is a complex scientific and technical task. This is due to a large number of internal, external and resultant factors. The aim of this work is to analyse these factors, assess them and their influence on the technological process of electrolysis and develop a comprehensive and mathematical model of aluminium production in the Soderberg electrolyser. The work analyses the technological process of primary aluminium production on the basis of the Bayer method and then on the basis of the Hall–Eru method. The existing methods and technologies for computer modelling of the technological process are analysed. The modern methods of analysis for thermal and electromagnetic fields in electrolysers are considered. On the basis of an in-depth analysis, a number of factors influencing the process of primary aluminium production are identified. Using the methods of system analysis to analyse the identified factors, a ranked list of factors according to the degree of influence is obtained. Using the Pareto diagram, we obtain a list of factors with maximum impact. A conceptual model of the technological process is derived. Based on the obtained conceptual model, the mathematical model of the technological process is derived. The conducted research may be useful to specialists in the field of metallurgy for the analysis of the technological processes of primary aluminium production.

Assessing the Life Cycle Performance in the Metallurgical Sector: A Case Study in Italy

This study compared two types of sheets: one made of steel and one made of aluminum, using Life Cycle Assessment (LCA), Life Cycle Costing (LCC), and Social Life Cycle Assessment (S-LCA). The LCA results show that the aluminum sheet had a greater environmental impact than the steel one in 11 out of 18 impact categories, such as a 5% higher Global Warming Potential, 3% higher Stratospheric Ozone Depletion, and 72% higher Ionizing Radiation. The main contributing factors were energy-intensive processes and bauxite processing associated with aluminum production. The LCC results also supported the findings of the LCA, demonstrating that the raw material, electricity, and labor costs for aluminum sheets were higher compared to steel ones, with the aluminum sheets costing €163 and the steel ones costing €19. However, the S-LCA results presented a contrasting perspective. They indicated that steel sheets exhibited poorer social performance compared to aluminum ones, particularly regarding child labor and discrimination, primarily due to the harsh working conditions in Ghana, the primary source of iron used in steel production. Overall, this study highlights the environmental superiority of steel screens over aluminum ones but also underscores the social challenges associated with steel production.

Comparative assessment of the state of main arteries in workers of the pivotal occupations in the coal and aluminum industries

Introduction. To prevent cardiovascular accidents and preserve the employability in workers in the pivotal occupations of the coal and aluminum industries it is required timely identification of risk groups for long-term asymptomatic damage to the atherosclerotic process of the arteries.
 Material and methods. The study included two hundred twenty two miners and 109 workers in the aluminum industry aged of 40–55 years (average age of miners – 47.1 ± 0.36 years, metallurgists – 47.64 ± 0.43 years, р = 0.367). All subjects underwent ultrasound investigation of the carotid and femoral arteries. Also anamnestic, anthropometric data, the presence of arterial hypertension, indices of lipid and carbohydrate metabolism were evaluated.
 Results. Miners were more often diagnosed with intimal thickening (41.9% vs. 27.5%, p = 0.011), in contrast to aluminum production workers, who were significantly more likely to have atherosclerotic plaques (57.8% vs. 43.2%, p = 0.0127). The frequency of generally accepted risk factors for atherosclerosis in both occupational cohorts (arterial hypertension, smoking, carbohydrate metabolism disorders, physical inactivity, obesity) was detected without significant differences. Miners with atherosclerosis were diagnosed with significantly higher average values of total cholesterol and low-density lipoprotein cholesterol, metallurgists with atherosclerosis showed hypertriglyceridemia.
 Limitations. The study was limited by the number of the examined persons undergoing periodic medical examination at the Research Institute for Complex Problems of Hygiene and Occupational Diseases.
 Conclusion. A more significant lesion of the main arteries in the form of atherosclerotic plaques with varying degrees of stenosis was found in aluminum production workers compared to miners, which was probably due to the more aggressive influence of harmful production factors in metallurgists. In this regard, it is recommended to conduct a screening ultrasound investigation of the main arteries at a periodic medical examination, which will identify a risk group for the timely prevention of cardiovascular complications.

Bubble Behavior and Anode Effect on Different Carbon Anode Designs in Cryolite Melt Applying a See-through Furnace

Anodic CO2 gas evolution is one of the main processes in the Hall-Héroult electrolysis cell for primary aluminium production. This work is a laboratory scale study of the effect of anode geometry, anode orientation and carbon anode material on bubble behavior and bubble properties in cryolite melt. Increased knowledge of the bubble behavior is important for improved design of industrial cells, but also for laboratory‐scale experiments. The anodes studied in this work are frequently applied for investigation of reaction kinetics and mass transport, anode effect, current efficiency, anode quality properties, etc. It is therefore of interest to study the bubble dynamics of these anodes in more detail because bubble evolution is relevant for all the above-mentioned phenomena.The anode potential has been shown to be highly dependent on anode geometry and orientation. For this study four different anode designs were made: horizontal (downward-facing), inverted horizontal (upward-facing), vertical, rod (with both vertical and horizontal surface). For most of the designs, characteristics such as bubble noise, bubble size, and wetting were obtained as a function of current density or anode potential/cell voltage. The bubble noise normally went through a maximum, while the bubble size decreased in the whole current density range. The wetting contact angle showed little variation with current density. It was assumed that the current density had a stronger effect on the contact angle through its effect on the bubble size than the polarization and associated surface roughening.Also, phenomena like nucleation, growth, coalescence, bubble detachment and anode effect were studied for both graphite and industrial carbon as anode material. The nucleation was more pronounced at the industrial carbon due to more active sites confirmed by CT analysis. The coalescence process was found to be independent of current density/potential and carbon anode material and was in the range 16-24 msec. On increased currents anode effect occurred on both anodes, the current being lower for the graphite anode at onset. Video recordings and electrochemical measurements showed more abrupt initiation of the anode effect on the graphite and a strong de-wetting of the anode. With the existence of a (C – F) surface compound on the anode, as long as the anode effect gas could escape the electrode surface, the anode seems to be electrochemically active towards both CO/CO2 and PFC formation during anode effect.In addition to the bubble characteristics and phenomena described, the impact of the results for better anode design for laboratory scale studies is discussed.

Impact of rolling processes in the production of aluminum packaging assessed through LCA

PurposeThe environmental impact of aluminum cans and aluminum food packaging has been extensively studied in the last years; most of the researchers focused their attention on the whole lifecycle: from the aluminum extraction to the end-of-life management, while there are no dedicated studies devoted to the detailed analysis of the rolling phase. The aim of this paper is to present an LCA analysis focused on the fabrication of the thin plates to be used for can and tray production; the work has been carried out by studying the “Laminazione Sottile” plant with a cradle-to-gate approach, considering as functional unit thin plates of two different alloys.Materials and methodsInventory data were collected from the “Laminazione Sottile S.p.A.” plant, and off-plant emissions from external goods and fuels were accounted for based on existent LCA databases. Gabi has been used as software to model the process and calculate the impacts, while the CML method has been used. Most of the data have been directly measured in the plant during 1 year of work.Results and discussionThe results showed that the most impactful phase is the extraction of aluminum or the use of primary aluminum. Focusing the attention on the manufacturing process, the foundry is the most impacting stage, and the high energy required to melt the aluminum leads to most of the emissions. Moreover, this contribution is probably underestimated in this work because the impacts related to the manufacturing of the facilities used (furnaces and so on) are not considered. Another interesting finding is that both the supply chain and the general consumption have a non-negligible impact, highlighting the necessity to optimize these two aspects by implementing new policies for purchasing and work organization.ConclusionsThe study highlighted that the production of primary aluminum is the most impacting step, followed by the foundry and the hot rolling. Production of thin aluminum plates by rolling requires a lot of energy, so the carbon footprint of these processes is quite high. The chemicals used in the rolling steps play also a role in the general impact of the whole process. The company continuously promotes improvements of the process to reduce the footprint and puts a lot of money and effort to introduce new sensors and technologies to monitor the consumptions and improve the processes.

Redefining the degree of industry greenness using input–output tables

Climate risk is a novel exposure that may rock the financial stability world-wide. For this reason the world banking regulation standards-setter – the Basel Committee on Banking Supervision (BCBS) – suggested considering pricing in the climate risk and adopting its relevant regulation. It listed input–output tables as one of the key tools to measure the climate riskiness of a borrower. However, most of the prior research considered carbon dioxide emissions when applying input–output tables. Same time there is a significant volume of research focusing on climate (or environmental) risk ratings. Nevertheless, both approaches might present only part of the larger climate-related financial risk implications. That is why, our research purpose is to develop full climate risk estimate by leveraging on the input–output tables and climate risk ratings. By doing so, we intend to demonstrate when the existing approaches yield sufficient information to make financial risk-related decision and when those should be improved by considering full climate risk justified in the current paper. The novelty of this work is the amalgamation of a known data source on environmental (climate) risk scores from Sustainalytics.com with the world input–output database (WIOD) for 2000–2014. The major finding of ours is that the greenness of industries is materially perturbed when considering WIOD-based full climate risk estimates as follows from an equivalent to the Leontief full production costs. We specifically find that aluminium as a commodity occurs much’browner’ from full climate risk perspective, than it seems from the marginal climate risk one. Hence, the steps taken by Australia to reduce aluminium production are necessary, but not sufficient. For the global welfare China has adopt a negative emission target (i.e., reduce more carbon dioxide, than is produced) to attain the objective of noticeable improvement in the global carbon footprint, particularly the one related to aluminium production. Our results are solicited by the Central Banks to accurately design the specialized lending facilities to truly green industries and projects.

Strength formation mechanism and curing system optimization of low-carbon cementitious materials prepared by synergistic activation of multiple alkaline solid wastes

Lack of proper disposal of carbide slag (CS), soda residue (SR), and red mud (RM), which are alkaline solid wastes released from the production of acetylene, soda ash, and alumina, respectively, adversely affects the environment. This study synthesized a new low-carbon cementitious material using CS-SR-RM-fly ash (FA) as raw material and optimized its curing method.The influence of raw material composition and various curing systems on the mechanical properties and microstructure of specimens was analyzed using compressive strength, chloride ion consolidation, XRD, FTIR, and SEM-EDS. The optimum ratio of CS:SR:RM:FA was determined to be 2:1:4:3, and the compressive strength of 3/28 d at room temperature (RT) sealed curing reached 10.7/22.1 MPa. The alkaline environment created by CS-SR-RM facilitated the decomposition of active components in FA and RM, contributing to the formation of a stable three-dimensional network comprising N-A-S-H gel, C-(A)-S-H gel, and Friedel's salt crystal product. High-temperature (HT) curing at 80 °C for 8 h significantly enhanced early strength, with strength growth rates of up to 147.7/29.9% compared with RT sealed curing at 3/28 d. HT curing promoted the rapid and steady growth of hydration products, resulting in increased structural compactness and improved strength. The present study offers suggestions for reducing the environmental pollution caused by alkaline solid waste and developing new resource utilization means.

Development of flux-cored wire of Fe – C – Si – Mn – Cr – W – V system with additives of carbon-fluorine-containing material and titanium

The paper considers research of quality of the electric arc coating obtained using flux-cored wire of the Fe – C – Si – Mn – Cr – W – V system with additives of carbon-fluorine-containing material and titanium. The formation of an electric arc coating was carried out using an automatic arc welding machine ASAW-1250 with a new chromium-containing flux-cored wire on plates made of St3 steel. To exclude mixing of the deposited metal with the substrate steel, multilayer surfacing was conducted. The surfacing mode was calculated and refined experimentally. The authors studied the composition and properties of the surface of the electric arc coating after surfacing. As a substitute for amorphous carbon they used a carbon-fluorine-containing material (dust of gas purification of aluminum production). Surfacing was carried out under a flux made from slag produced by silicomanganese with a high content of sulfur. A regression analysis of influence of the deposited layer’s chemical composition on its hardness and wear rate was carried out and mathematical models of the investigated performance characteristics of the electric arc coating were obtained. With an increase in the content of chromium, tungsten, carbon and silicon, hardness of the deposited metal and its resistance to abrasive wear increase. The results of the conducted research make it possible to develop measures ensuring the required level of performance characteristics of the electric arc coating and can be used to make a forecast of hardness of the deposited layer and its wear resistance when the chemical composition of the metal changes, to predict the operational resistance of rolling rolls deposited with wires of the PP-Np-35V9Kh3SF type. Mathematical models of hardness of the deposited layer and its wear resistance help to clarify the mechanism of hardening and formation of protective properties of the surface layers of rolling rolls by means of electric arc coatings deposited with flux-cored wires.

Genetic Basis of Acinetobacter sp. K1 Adaptation Mechanisms to Extreme Environmental Conditions.

Anthropogenic pollution often leads to the generation of technosols, technogenic soils with inhospitable conditions for all living organisms including microbiota. Aluminum production near Ziar nad Hronom (Slovakia) resulted in the creation of a highly alkaline and heavy-metal-rich brown mud landfill, from which a bacterial strain of a likely new species of the genus Acinetobacter, Acinetobacter sp. K1, was isolated. The whole-genome sequence analysis of this strain confirmed the presence of operon units enabling tolerance to the heavy metals copper, zinc, cobalt, cadmium, chromium, and metalloid arsenic, which are functionally active. Despite the predominance of plasmid-related sequences in the K1 genome, the results indicate that most of the resistance genes are chromosomally encoded. No significant alkali tolerance of Acinetobacter sp. K1 was observed in vitro, suggesting that community level mechanisms are responsible for the survival of this strain in the highly alkaline, brown mud bacterial community.

Optimization of Pore Formation Process of Lotus Aluminum by Phase Field Simulation

Abstract We have used multi-phase field simulation to mimic the actual process of lotus aluminum production, i.e., unidirectional solidification of aluminum in a hydrogen atmosphere. We used PD control and PID control, conventional methods of feedback control, to control the pore width precisely in the simulation. The pore width was shown to decrease slowly in PID control due to the slow feedback of I-control, and PD control was shown to produce stable long pores, although the pore width became larger than the target pore width. The initial hydrogen concentration in the liquid, which was controlled by atmospheric hydrogen pressure, had a significant effect on the pore growth; the higher the hydrogen concentration, the thicker the pore width and vice versa. It was also clarified that the pore width and the elongation length of the pore took various values depending on the combination of PD parameters even if the same target value was set.

Synthesis of Rankine cycle systems with cascade and separate configurations utilising multiple heat sources at different temperature levels

The optimisation of Rankine cycle systems is mainly influenced by the type of heat source, working fluid selection, process components, control strategy, component layout and sizing, and has been recognised as a promising way to contribute to the development of renewable and sustainable energy systems. In this study, a combined steam-organic Rankine system is proposed to recover waste heat from aluminium production at various temperature levels and heat from solar, geothermal and biomass renewable sources. Based on a case study in a Slovenian city, the operating conditions of two different configurations are optimised for individually positioned cycles and for a cascade design of these cycles. The process design and its characteristics are captured in a flowsheet structure formulated with a non-linear programming model and solved in GAMS. The comparison of the optimal performance of the studied systems shows the better performance of the separate design, generating a total power of more than 1.6 MW, while in cascade design 11.4% less power is produced. The flexibility and adaptability of the system to different energy sources are investigated and the trade-offs associated with different system configurations are discussed.

Reduction of Fine Dust Emissions During Sintering of Nepheline-Lime-Stone Charge

It was found that dust of electrostatic precipitators supplied to the sintering furnace from the hot end precipitates little on the sintered material of the raw charge of alumina production of JSC "RUSAL Achinsk", increases the dust turnover and dust release of solid pollutants from the furnace into the atmosphere. In order to increase efficiency of purification of atmospheric air from fine dust of electric precipitators it is proposed to remove it from dust circulation of the sintering furnace and dispose of it separately in technology of road mixture when laying the base of road pavements. The introduction of this technology provides a reduction in atmospheric emissions from 18.965 to 5.859 g/s, a reduction in coal consumption by 1.39 kg of conventional fuel for the production of 1 ton of sinter and savings of coal fuel by 8350 tons per year.

Numerical Investigation of Electro-Thermal Field Distribution Law of Busbar under Different Operating Conditions

The electro-thermal state of a busbar system of electrolysis cells for aluminum production represents the main factor affecting hydromagnetic stability and current distribution. Based on the busbar system of a 500 kA aluminum electrolytic cell, an overall busbar electro-thermal field coupling calculation model was established based on ANSYS. The characteristics of busbar temperature, current density, and voltage drop distribution were analyzed. In addition, the electro-thermal distribution of the busbar system was simulated under different current intensities, ambient temperatures, and heat transfer coefficients. The results show that the temperature distribution of the riser busbar and the cathode busbar is higher in the middle location and tends to decrease along the two sides. Differences in heat conduction and heat dissipation environment are the main factors affecting the distribution of the busbar system’s electro-thermal field, while the Joule heat of the current is not the major factor. Increasing the current intensity will increase the average temperature and average voltage drop of the busbar. With an increase in the ambient temperature, the average busbar temperature increases significantly, and the voltage drop of the busbar also increases. With an increase in heat transfer coefficient, the average temperature and voltage drop of the busbar decreases.