Industrial Production Of Aluminium Research Articles

Experimental Study on The Partial Replacement of Cement with Red Mud in Concrete

These days the construction industry is fully developed due to a massive increase within a short period of time in the use of cement and concrete for multiple construction activities. The same rate is expected to continue in the next decade and this may cause global environmental impacts. The raw materials needed to manufacture cement and produce concrete provide less and require more energy for production. This increasing demand is causing a rapid depletion of resources. To overcome this situation, it is very important to use industrial waste and by-products for the manufacture of cement and concrete construction. Red mud is the extensive amount of industrial waste generated during the production of alumina. It has been found that for every 1 ton of alumina 1.2 to 1.3 tons of red mud waste is generated. As red mud has complex properties, the disposal process becomes quite challenging Disposal of this waste was the first prime problem encountered by the alumina industry after the adoption of the Bayer process. The conventional method of disposal of the red mud in ponds has often adverse environmental impacts as during monsoons the waste may be carried by run off to the surface water courses and as a result of percolating may cause contamination of ground water. Further disposal of large quantities of red mud dumped, poses increasing problems off storage occupying a lot space over the years many attempts have been made to find a use for red mud but nobody have proven to be economically satisfactory. Red mud or red sludge is a waste product generated in the industrial production of Aluminum via Bayer’s process of refining bauxite enrooted to alumina. With about 150 million tons (Globally) & 9 million tons in India of this hazardous material produced annually, red mud is one of the most important disposal problems in the mining industry. In this study, Mix was designed for M25 grade of conversational concrete. 6 mix were made in which Red mud were substituted by weight of cement in varying proportion 0%, 5%, 10% ,15%,20% and 25%. We evaluated the strength of concrete by performing tests which are compressive strength, flexural strength at the age of 7days and 28day. Study results revealed that 15% cement can be the optimally replaced by red mud beyond which compressive strength, Flexural strength deceasing. We find out that Compressive strength increase by 3.80 %, Flexural strength increase by 9.42% and replacing cement with red mud at 15%. However, the optimum level was observed as 15% without deceasing in strength. Study results revealed that 15% cement can be the optimally replaced by red mud beyond which compressive strength, Flexural strength deceasing. We find out that Compressive strength increase by 3.80 %, Flexural strength increase by 9.42% and replacing cement with red mud at 15%. However, the optimum level was observed as 15% without deceasing in strength.

Contour Maps for Simultaneous Increase in Yield Strength and Elongation of Hot Extruded Aluminum Alloy 6082

In this paper, the Conditional Average Estimator artificial neural network (CAE ANN) was used to analyze the influence of chemical composition in conjunction with selected process parameters on the yield strength and elongation of an extruded 6082 aluminum alloy (AA6082) profile. Analysis focused on the optimization of mechanical properties as a function of casting temperature, casting speed, addition rate of alloy wire, ram speed, extrusion ratio, and number of extrusion strands on one side, and different contents of chemical elements, i.e., Si, Mn, Mg, and Fe, on the other side. The obtained results revealed very complex non-linear relationships between all of these parameters. Using the proposed approach, it was possible to identify the combinations of chemical composition and process parameters as well as their values for a simultaneous increase of yield strength and elongation of extruded profiles. These results are a contribution of the presented study in comparison with published research results of similar studies in this field. Application of the proposed approach, either in the research and/or in industrial aluminum production, suggests a further increase in the relevant mechanical properties.

Red mud regulates arsenic fate at acidic pH via regulating arsenopyrite bio-oxidation and S, Fe, Al, Si speciation transformation

Red mud (RM) as waste of industrial aluminum production is piling up in huge ponds. RM could be a cost-effective adsorbent for heavy metals, but adsorption is vulnerable to pH changes, metal ions speciation and the occurrence of iron bearing minerals. In this study, the precipitation and elemental speciation transformation relevant to arsenic fate in responding to the addition of RM during arsenopyrite bio-oxidation by Sulfobacillus thermosulfidooxidans was investigated. The results show that the addition of RM significantly changed the arsenic precipitation and the solution chemistry and thus affected the arsenopyrite bio-oxidation and arsenic fate. An addition of a small amount (≤ 4 g/L) of RM substantially promoted arsenopyrite bio-oxidation with formation of SiO2 @ (As, Fe, Al, Si) spherical nanoparticles that can enhance the stability of the immobilized arsenic. The SiO2-based spherical nanoparticles precipitate was mainly composed of jarosites, amorphous ferric arsenate and crystalline scorodite, and its formation were controlled by Fe3+ concentration and solution pH. An addition of increased amount of RM (≥ 6 g/L) resulted in a significant increase of the solution pH and a decrease in the Fe2+ bio-oxidation activity, and spherical nanoparticles were not formed. Consequently, the dissolution of arsenopyrite was inhibited and the release of arsenic was blocked. This study suggests the applicability of RM in mitigation of arsenic pollution from bio-oxidation of As-bearing sulfide minerals.

Building of a digital model of aluminum electrolysis modes

The article discusses the issues of constructing a digital model of aluminum electrolysis modes. This model allows to achieve the specified criteria of the production process on the basis of scientific processing of historical data accumulated during the industrial production of aluminum at factories using a mathematical apparatus as well as to obtain recommendations on the values of control parameters. The study is aimed at achieving the business goals of the company’s management in particular on increasing of the profits by improving the quality and quantity of products with reduced production costs.

Processes soft modeling based on stacked autoencoders and wavelet extreme learning machine for aluminum plant-wide application

Data-driven soft modeling has been extensively used for industrial processes to estimate key quality indicators which are hard to measure by some physical devices. However,the existing deep soft methods faces the challenge of training efficiency, gradient diminishing and explosion. Constructing an accurate and robust soft model is still a challenging topic from an application point of view. This paper develops an effective and efficient soft method (SAE-WELM) for processes modeling. First, a stacked autoencoder (SAE) is used to extract the deep features. Then, a top-layer extreme learning machine (ELM) is further applied to a plant-wide industrial aluminum production process. The activation function is wavelet kernel. Finally, the approximation and convergence of the proposed SAE-WELM are theoretically proved. The industrial case demonstrates that SAE-WELM captures the deep features faster than other iterative-based neural networks, and the accuracy and robustness outperform the existing state-of-the-art methods.

Alumina Solubility in NaF-KF-LiF-AlF3-Based Low-Temperature Melts

NaF-KF-LiF-AlF3-based low-temperature electrolytes have attracted great interest because of their potential to optimize and improve current industrial aluminum production methods. In the present study, the saturated alumina solubility in quaternary NaF-KF-LiF-AlF3-based melts (total cryolite molar ratio $$ {\text{CR}} = \left( {n_{\text{NaF}} + n_{\text{KF}} + n_{\text{LiF}} } \right)/n_{{{\text{AlF}}_{3} }} $$ of 1.3) with both KF and LiF content of 0 mol.% to 20 mol.% were evaluated by measuring the weight loss of a rotating corundum disk over the temperature range of 800–920°C. The effects of the KF content, LiF content, and temperature on alumina solubility are discussed in detail. The results fit well with the following empirical equation within the temperature of 830–890°C: ω(Al2O3)sat = A × (t/1000)B, where A = 0.3101[KF] − 0.1254[LiF] − 0.0057[KF]2 + 0.0028[LiF]2 + 4.486, B = 0.3839[KF] + 0.0368[LiF] − 0.0140[KF]2 + 0.0057[LiF]2 + 4.913, and t is the temperature in Celsius. Alumina solubility diagrams at various temperatures are illustrated based on the empirical regression equation obtained. Finally, some problems and challenges preventing the application of these low-temperature melts in industry are discussed.

Progress in Application of Energy-Saving Measures in Aluminum Reduction Cells

The Hall–Herault process is the only methodology applied in the industrial production of aluminum. Energy saving has long been the focus of the aluminum industry since its invention. Nowadays, the pursuit of high productivity, low DC energy consumption and large-scale cell adds new urgency to energy saving, among which the improvement of magnetic-hydro-dynamic (MHD) stability in aluminum electrolysis cells plays a very important role. This article reviewed the developments and applications of the measures in improving MHD stability in terms of structure, effectiveness, simulation, pilot and industrial results. Also some studies were conducted on a TiB2 wettable cathode. At the end, some suggestions on further reduction of energy consumption in the future are proposed.

Comparative Analysis of Biological Effects Induced on Different Cell Types by Magnetic Fields with Magnetic Flux Densities in the Range of 1–60 mT and Frequencies up to 50 Hz

Moderate static magnetic fields (SMFs) are generated from sources such as new-generation electric trams and trains, electric arc welding, and magnetic resonance imaging (MRI) devices, as well as during the industrial production of aluminium, while extremely low frequency pulsed magnetic fields (ELF-PMFs) are produced by house power installations, household appliances, and high voltages transmission lines. Moderate SMFs and ELF-PMFs with magnetic flux densities (B) in the range of 1–60 mT and frequencies (f) up to 50 Hz are common MF exposure sources for the population. Even though humans are continually exposed to these MFs, to date no definitive endpoint has been drawn about their safety. In this review, the state of knowledge about the biological effects induced by these MFs on different cell types will be addressed. In our own observation, the putative modulation of Ca2+/H+ and Na+/H+ plasma membrane antiporters of human peripheral blood lymphocytes (PBLs) was found to occur after a 24 h exposure to a 6 mT SMF, and the bystander effect observed on U937 cells cultivated for up to 6 h in the conditioned medium harvested from human PBLs previously exposed for 24 h to the same MF (secondary necrosis induction) will be also herein discussed.

Momentum‐based approximation of incompressible multiphase fluid flows

SummaryWe introduce a time stepping technique using the momentum as dependent variable to solve incompressible multiphase problems. The main advantage of this approach is that the mass matrix is time‐independent making this technique suitable for spectral methods. A level set method is applied to reconstruct the fluid properties such as density. We also introduce a stabilization method using an entropy‐viscosity technique and a compression technique to limit the flattening of the level set function. We extend our algorithm to immiscible conducting fluids by coupling the incompressible Navier‐Stokes and the Maxwell equations. We validate the proposed algorithm against analytical and manufactured solutions. Results on test cases such as Newton's bucket problem and a variation thereof are provided. Surface tension effects are tested on benchmark problems involving bubbles. A numerical simulation of a phenomenon related to the industrial production of aluminium is presented at the end of the paper.

New polymeric/inorganic hybrid sorbents based on red mud and nanosized magnetite for large scale applications in As(V) removal

Red mud (RM), a waste product generated in the industrial production of aluminium, was recovered for a second use as As(V) adsorbent. RM adsorption properties were compared to those obtained with a nanostructured in-lab synthesized iron oxide, magnetite. Operational problems associated with powdery consistency of raw materials were solved with the synthesis of new polymeric/inorganic hybrid sorbents by dispersing red mud and magnetite in chitosan. The behaviour of raw red mud and magnetite towards As(V) adsorption has been critically compared with that observed for the hybrid materials. pH dependence studies demonstrated that near neutral environments favour As(V) elimination. The sorption kinetics for the iron oxides showed that equilibrium was reached in less than 3h for raw materials and up to 15h for immobilized red mud and magnetite. The amount of arsenic sorbed on the four different sorbents as a function of the equilibrium arsenic concentration has been fitted to a Freundlich isotherm and a multilayer adsorption mechanism is proposed. Finally, continuous flow experiments were developed using chitosan immobilized red mud. Results allowed selecting batch conformation as the most effective for As(V) removal.

From Science to Industry: The Sites of Aluminium in France from the Nineteenth to the Twentieth Century

This paper explores the history of the isolation and industrial production of aluminium in France, from the work of Henri Sainte-Claire Deville in the 1850s to the latter part of the twentieth century, focusing on the relationships between academic research and industrial exploitation. In particular, it identifies a culture and organisation of research and development, “learning-by-doing,” that emerged in the French aluminium industry following the establishment of the first electrolytic production facilities in the late 1880s by Paul Héroult, who, along with the American Charles Hall, patented the electrolytic method of producing the metal. This French method of R&D was a product both of a scientific culture that saw a continuity between scientific research and industrial application, and of a state policy that, unlike in Germany or the United States, was late to recognise the importance of fostering, on a large scale, the relations between academic chemistry and industry. It was only after World War II that the French state came fully to recognise the importance of underpinning industry with scientific research. And it was only from the 1960s, in the face of intensifying global competition, the risks of pollution, and the cost of energy, that the major aluminium firm Pechiney et Cie was able to replace a culture of “learning-by-doing” by one that integrated fundamental science with the production process.

The Aluminum Smelting Process and Innovative Alternative Technologies

Objective:The industrial aluminum production process is addressed. The purpose is to give a short but comprehensive description of the electrolysis cell technology, the raw materials used, and the health and safety relevance of the process.Methods:This article is based on a study of the extensive chemical and medical literature on primary aluminum production.Results:At present, there are two main technological challenges for the process—to reduce energy consumption and to mitigate greenhouse gas emissions. A future step may be carbon dioxide gas capture and sequestration related to the electric power generation from fossil sources.Conclusions:Workers' health and safety have now become an integrated part of the aluminum business. Work-related injuries and illnesses are preventable, and the ultimate goal to eliminate accidents with lost-time injuries may hopefully be approached in the future.

Vacuum Carbothermic Reduction of Alumina

The current industrial production of aluminum from alumina is based on the electrochemical Hall-Héroult process, which has the drawbacks of high-greenhouse gas emissions, reaching up to 0.70 kg CO2-equiv/kg Al, and large energy consumption, about 0.055 GJ/kg Al. An alternative process is the carbothermic reduction of alumina. Thermodynamic equilibrium calculations and experiments by induction furnace heating indicated that this reaction could be achieved under atmospheric pressure only above 2200°C. Lower required reaction temperatures can be achieved by alumina reduction under vacuum. This was experimentally demonstrated under simulated concentrated solar illumination and by induction furnace heating. By decreasing the CO partial pressure from 3.5 mbar to 0.2 mbar, the temperature required for almost complete reactant consumption could be decreased from 1800°C to 1550°C. Deposits condensed on the relatively cold reactor walls contained up to 71 wt% of Al. Almost pure aluminum was observed as Al drops, while a gray powder contained 60–80% Al and a yellow-orange powder contained only Al4C3, Al-oxycarbides and Al2O3.

Study on Spark Plasma Sintering of NiAl<sub>2</sub>O<sub>4</sub>-Metal Inert Anodes

NiAl2O4-metal composite material is an effective candidate for anodes used in industrial production of aluminium as a substitute for graphite anodes. NiAl2O4-Cu-Ni anode was prepared by spark plasma sintering in present paper. According to the density and electrical conductivity of the anodes, the optimal process parameters were given and the result showed that sintering temperature had the most significant influence on the properties of the inert anodes. Moreover, NiO was added to the inert anodes. The results showed that adding NiO will highly increase electrical conductivity of the inert anodes. SEM and optical microscope were applied to study the mechanism of the effect of NiO on the inert anodes.

A High‐Temperature Multinuclear NMR Study of Na3AlF6–FeO andNa3AlF6–Fe2O3 Melts

AbstractIn the Hall–Héroult process for the industrial production of aluminum, iron oxide impurities are known to lower the current efficiency as well as the metal quality. Iron can be present in the di‐ or trivalent form. The nature of dissolved FeIII and FeII species and the reactions taking place in cryolitic melts have been investigated by high‐temperature NMR spectroscopy. The evolution of 27Al, 23Na, and 19F NMR chemical shifts are reported in the Na3AlF6–FeO and Na3AlF6–Fe2O3 systems for different iron oxide contents. They express the formation of oxofluoroaluminate species. For the Na3AlF6–FeO system, the 19F signal appears only after 14 minutes at 1020 °C. The line position is shifted with heating time. This evolution is associated with a narrowing of the 27Al signal due to a decrease in the content of paramagnetic compounds in the sample. This effect is probably caused by the evaporation of an FeII compound, as already mentioned in the literature. For the Na3AlF6–Fe2O3 system we have never observed the 19F NMR spectra over the full heating time (ca. 30 min). This could be due to the influence of paramagnetic FeIII nuclei, probably in FeF63– species present in the melt. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

F2Al(mu-eta2:eta2-O2)AlF2: an unusual, stable aluminum peroxo compound.

The oxidation processes in the industrial production of aluminum from cryolite melts are not fully understood. Oxidation of AlOF2- leads initially to AlOF2 radicals. The structure of the AlOF2 dimer and several oxidized and reduced forms of this compound are investigated by theoretical methods and compared to analogous boron and gallium compounds. The thermodynamic stability of these compounds is investigated. It is shown that the dimeric compound of AlOF2 contains a symmetric peroxo bridge and is unexpectedly stable toward decomposition.

Modeling and simulation of the industrial production of aluminium: the nonlinear approach

We report on the numerical simulation of the industrial production of aluminium. The motion of the two nonmiscible conducting fluids is modeled through the incompressible Navier–Stokes equations coupled with the (parabolic) Maxwell equations. Stabilized finite elements techniques and an arbitrary Lagrangian Eulerian formulation (for the motion of the interface separating the two-fluids) are used in the numerical simulation. The industrial problem and the modeling strategy are presented in details. An outline of the numerical analysis of the problem, with a special emphasis on conservation and stability properties is provided. Examples of numerical simulations of the industrial case are eventually presented.

Simulations of MHD flows with moving interfaces

We report on the numerical simulation of a two-fluid magnetohydrodynamics problem arising in the industrial production of aluminium. The motion of the two non-miscible fluids is modeled through the incompressible Navier–Stokes equations coupled with the Maxwell equations. Stabilized finite elements techniques and an arbitrary Lagrangian–Eulerian formulation (for the motion of the interface separating the two fluids) are used in the numerical simulation. With a view to justifying our strategy, details on the numerical analysis of the problem, with a special emphasis on conservation and stability properties and on the surface tension discretization, as well as results on tests cases are provided. Examples of numerical simulations of the industrial case are eventually presented.

Mass transport considerations for the development of oxygen-evolving anodes in aluminum electrolysis

Oxygen-evolving, non-consumable anodes are being developed for use in industrial aluminum production. Ceramic-type electrodes dissolve slowly into the electrolyte, a process governed by mass transport conditions. For achievable anode life, factors determining mass transfer rates at the cathode are generally more important than those at the anode. This is discussed by means of model calculations and using experimental results. The roles of incomplete alloying of anode constituents with the aluminum upon reduction at the cathode and of metal dissolution from the cathode are also treated.

An investigation of the recovery of cryolite from alumina‐electrolyte froth by flotation

AbstractIn the industrial production of aluminium by the electrolysis of alumina, electrolyte froth, which is a mixture of carbon and cryolite is obtained at a rate of 50 kg of froth per ton of aluminium produced. Cryolite can be recovered from this mixture by flotation. In this study, the effects of the following parameters on flotation were experimentally investigated: particle size, type, combination, dosage and ratio of reagents, and conditioning time. It is found that it is possible to decrease the carbon content of cryolite below 1% by suitably choosing the operating parameters. Electrolyte froth must be ground to —100 mesh size for the liberation of carbon particles captured in the cryolite matrix. Any combination of two of the reagents, kerosene, fuel oil, creosote and terebenthene yield good results if used together with pine oil. Pine oil is found to be a more effective frother compared to Pril, a commercial detergent. Satisfactory separations are obtained when a kerosene‐fuel oil mixture (50:50, v/v) is used as the collector with a dosage of 3.7 kg per ton of feed together with pine oil, the frother, with a dosage of 0.095 kg per ton of feed.