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Singh R.,Visvesvaraya National Institute of Technology | Khatirkar R.K.,Visvesvaraya National Institute of Technology | Chouhan R.N.,Jawaharlal Nehru Aluminium Research Development and Design Center | Sapate S.G.,Visvesvaraya National Institute of Technology
Transactions of the Indian Institute of Metals

AA3004 aluminium alloy is most widely used in the beverage industry due to its excellent deep drawing properties and corrosion resistance. During deep drawing of the AA3004 sheets, the ‘earing phenomenon’ has to be minimized for economic advantage. In AA3004 and modified AA3004 alloys (like AA3104), this can be achieved by tailoring the crystallographic texture of the fully recrystallized sheet. Conventionally, AA3004 sheets are produced through direct chill (DC) casting route. In the present study, a twin roll cast AA3004 sheet is used for further processing (cold rolling and annealing). The texture comprised mainly of Cu ({112} 〈111〉), Brass ({110} 〈112〉) and S ({123} 〈634〉) orientations in the as-cast as well as cold rolled condition (Cu, Brass and S components being stronger in the cold rolled condition as compared to as-cast material). After complete recrystallization of 90 % cold rolled sheet, cube texture are deviated from ideal cube ({100} 〈001〉) (5°–10°) along with formation of Goss ({110} 〈001〉) and P{011} 〈122〉 components. This was in contrast to the DC casting route, where strong cube recrystallization texture is obtained. © 2016 The Indian Institute of Metals - IIM Source

Agnihotri A.,Jawaharlal Nehru Aluminium Research Development and Design Center | Pathak S.U.,Visvesvaraya National Institute of Technology | Mukhopadhyay J.,Indian Institute of Technology Gandhinagar
Transactions of the Indian Institute of Metals

Aluminium reduction process is a nonlinear, time varying electrochemical process, in which alumina (Al2O3) dissolved in cryolite (Na3AlF6) is electrolysed to produce molten aluminium. In industrial practice the term noise refers to unsteady voltage signal in the reduction cell or random and/or uncontrolled fluctuations in the cell voltage; it can be used to identify problems in the cell operation. The main objectives of the reduction process is to achieve as high a current efficiency as possible with minimum energy consumption. Noises of certain frequencies are generally considered unfavorable to cell current efficiency and energy consumption. Therefore, noise control is an important issue in commercial cell automatic control system. The present paper analyses noise from different sources during cell operation and their possible causes with help of Fast Fourier Transformation techniques in terms of frequency and amplitudes of the fluctuations. An advanced data acquisition system was used for collecting the data required for the noise studies. The characterization of the three types of noise generated is discussed. Real-time algorithms have been implemented to allow on-line estimation of the noise sources and intensities. © 2013 Indian Institute of Metals. Source

Agnihotri A.,Jawaharlal Nehru Aluminium Research Development and Design Center | Pathak S.U.,Visvesvaraya National Institute of Technology | Mukhopadhyay J.,Indian Institute of Technology Gandhinagar
Advanced Materials Research

The Hall-Heroult process for the production of aluminium is based on the electrochemical reduction of alumina (Al2O3) dissolved in a cryolite (Na3AlF6) based electrolyte. Instability in cell voltage is referred to as noise. Normal voltage noise is inevitable due to bubble evolution and it has little effect on performance parameters such as, current efficiency and power consumption. Metal rolling noise (wavy noise) is caused by the disturbances in cell magnetic field and it affects the cell current efficiency adversely. Investigating the causes of the cell instability in the aluminium smelting cells can lead to better cell performance. Understanding the variation in cell voltage is critical for cells, because magnitude of voltage determines the energy consumption pattern in the process and hence, any saving on voltage can save energy. Voltage affects the current efficiency of the cell and an optimum cell voltage leads to higher current efficiency without compromising on energy consumption. Magnetic, current distribution, heat loss and voltage at zero current measurements along with online current and voltage signal can help to identify the problems and their combined effects on the performance of the cells. In order to estimate the loss in current efficiency of the aluminum electrolysis cells due to metal instabilities, measurements were performed and data analyzed. The present paper analyses the effect of voltage fluctuations (noise) during metal instability along with cause of instability and its effect on current efficiency of the cell. Measurements carried out to estimate the deviations from the normal cell operations are also discussed. © (2014) Trans Tech Publications, Switzerland. Source

Bhukte P.G.,Jawaharlal Nehru Aluminium Research Development and Design Center | Chaddha M.J.,Jawaharlal Nehru Aluminium Research Development and Design Center
Journal of the Geological Society of India

India is endowed with more than 3000 million tons of bauxite resources. Out of total India reserves, about 70% reserves are concentrated in Eastern Ghats (Odisha and Andhra Pradesh) region. Majority of the Eastern Ghat bauxite deposits are located at high altitude (high level type) and have been developed on khondalite and charnockite group of rocks with different geomorphological conditions. These are formed at an elevation of about 900- 1400 meter above mean sea level (msl). The physico-mechanical and technological properties of these bauxite vary widely depending upon the parent rock composition, mode of origin, geomorphological position, duration and age of bauxite formation. In the Bayer process the most important parameter that decides the economic importance is the quality of bauxite which again decides the digestion parameters for alumina extraction. Jawaharlal Nehru Aluminium Research Development and Design Centre (JNARRDC) is in process of evaluating the bauxite and laterite deposits of India for its suitability for commercial applications. The present paper highlights the geological and geomorphological features of Eastern Ghats bauxite deposits and their technological characteristics. These studies are required to evaluate the bauxite in terms of their suitability for metallurgical and non metallurgical applications. © 2014 Geological Society of India. Source

Rai S.,Jawaharlal Nehru Aluminium Research Development and Design Center | Wasewar K.L.,Visvesvaraya National Institute of Technology | Lataye D.H.,Visvesvaraya National Institute of Technology | Mukhopadhyay J.,Jawaharlal Nehru Aluminium Research Development and Design Center | Yoo C.K.,Kyung Hee University
International Journal of Environmental Science and Technology

In this study, feasibility of using seawater to neutralize alkaline red mud for its safe disposal has been studied using Taguchi's design of experimental methodology. Parameters such as weight of red mud, volume of seawater, stirring time and temperature were tested at three levels to study their effect on response characteristic, i.e., pH of the neutralized slurry. The analysis of variance showed that volume of seawater added and quantity of red mud are the two significant parameters with 53.59 and 44.92 % contribution each, respectively. Under the optimized parameters, pH value of red mud slurry reaches to about 8.0 which is within disposable limits. When seawater or other Ca- and Mg-rich brines are added to caustic red mud, the pH of the mixture is reduced causing hydroxide, carbonate or hydroxy carbonate minerals to be precipitated. This mechanism of neutralization process has been explained with emphasis on chemical analysis, mineralogy and morphology of the neutralized red mud. The process improved the physical characteristics of red mud with entrained liquor becoming non-hazardous water with reduced alkalinity. The results would be extremely useful in the process of safe disposal of red mud. © 2012 CEERS, IAU. Source

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