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By Cassandre Nowicki, Louis Gosselin, Carl Duchesne

"Quebec's primary aluminium production industry consumes roughly 39 TWh of electricity per year and is accountable for roughly 7 million tons of CO2 equivalent. By tapping only a small portion of waste heat and integrating it inside the production facility itself, we can significantly reduce GHG emissions and energy consumption. Although the amount of thermal waste can be adequately estimated by applying an energy balance to production processes, this provides very little information on the quality of waste heat and its potential for integration. A measure of exergy is required. Waste heat streams characterized by high exergy content may generally offer valuable incentives for recovery and integration. More generally, exergy values limit integration possibilities. An exergy analysis is provided for the aluminium electrolytic reduction process. This is meant to guide future heat recovery initiatives and energy efficiency measures.IntroductionCanada is one of the world leaders in primary aluminium production and 92% of its aluminium production capacities are located in the province of Quebec. In 2007, production capacity reached 2,786,000 tons in Quebec alone. Since it is estimated that 2.5 equivalent tons ofCO2 are released for each ton of aluminium produced in Canada, Quebec's aluminium production industry is accountable for roughly 7 million tons of CO2 yearly [1, 2]. Furthermore, with an average electricity consumption of 14 MWh per ton, primary aluminium accounts for 39 TWh of electricity per year in Quebec and this energy consumption represents 350 thousand tons ofCO2 equivalent [3, 4]. Natural gas consumption associated with primary aluminium production accounts for less than 1 TWh, but it represents an additional 350 thousand tons of CO2 equivalent [ 4].This work is meant to provide a tool to guide future efforts towards heat recovery and energy efficiency in the primary aluminium industry. Waste heat recovery and thermal integration can cut down both energy consumption costs and GHG emissions. In a primary aluminium production facility, waste heat represents roughly half of the energy input into the Hall-Heroult process. Tapping only a small portion of this energy could reduce natural gas and electricity consumption significantly. In order to evaluate how much of this energy is actually usable, we propose to apply an exergy analysis to individual transformation processes in an aluminium production facility, such that a potential to do work can be assigned to every waste heat flux. The approach will be described in the next section."

Jan 1, 2012

By Christopher R. Casias

A basic methodology is presented (employing both standard and theoretical assessment, analysis. and data interpretation techniques) for classifying waste containing trace levels of radionuclldes. Despite increased regulatory requirements for handling. transporting. and disposing of such waste: (I) no formal characterization methodology has yet been Implemented. and (2) no limits have been set to define the point at which a waste material is considered to be low-level and below which it Is "below regulatory concern" (BRC) or can be considered to contain no more than a diminimus level of radioactivity (i.e . is nonradioactive). 'I1le concept of diminimus limits specific to waste streams and waste forms is introduced. and a mechanism fur evaluating waste In relation to BRC and diminimus limits is outlined. This methodology can be used to perform a complete and adequate characterization of waste for classification according to its level of radioactivity.

Jan 1, 1992

By Sheng-hai Yang

The electrochemical synthesis was conducted in anhydrous ethanol solvent mixed with conductive reagent when tantalum plate was used as anode and stainless steel plate as cathode. The effects of different conductive reagents (such as NH4Br, (CH3)4NCl, (C4H9)4NCl), conductive reagent concentration and the space on the cell voltage and the current density were investigated. The current efficiency of electrosynthesis was more than 95%. The electrolyte, a mixed solution was then undergone air distillation and vacuum distillation to get the final product which was characterized by Fourier Transform Infrared(FTIR) spectroscopy, Raman spectra, 1H-Neclear Magnetic Resonance(1H-NMR) spectroscopy. Carbon and hydrogen contents in the product were determined by elemental analysis instrument. Results consistently show that the product was tantalum penta-ethoxide.

Jan 1, 2006

By Lifeng Zhang, Zineb Benouahmane, Yaqiong Li

Experimental oxidation tests at high temperature (1000-1200 °C) on SiC samples have been respectively performed under wet and dry air atmosphere for different holding times. The thickness of thermally grown oxide was experimentally measured by DEKTAK Stylus Profilometry. The results showed that the oxidation rate was increased with temperature and holding time, corresponding to a passive oxidation regime which led to the formation of SiO2 layer. The sessile drop method was employed in order to measure the contact angles between Si and SiC at high temperature. Contact angle can be varied from 39.6° to 75.6° by controlling the atmosphere. The deoxidation of the oxide layer and infiltration of liquid silicon caused a decrease in the contact angle.

Jan 1, 2016

By Bryn Harris

Much has been written over the past twenty years on the removal and chemical stabilization of arsenic from metallurgical process solutions. This paper reviews again the latest developments in this field, and concludes as before that the high-iron arsenical ferrihydrites, together with the high temperature arsenic minerals, scorodite and Type II, remain as the best and most viable vehicles for industrial control and disposal. However, a cautionary note is introduced, in that chemical environments cannot be considered in isolation, and that cogniscence has to be taken of microbiological activity in determining the disposal method. Data are also presented on a survey of industrial practice, which shows that arsenical ferrihydrite is by far the most widely-practiced and accepted method used worldwide. Finally, the disaster in Bangladesh is briefly discussed with reference to lessons that the metallurgical community might learn from this.

Jan 1, 2003

By Luis G. S. Sobral, Gabrielle N. Bard

Copper sulphides Concentrates, from the flotation process of copper primary ore; contain, commonly, small amounts of precious metals, such as gold and silver. During the smelting process of those concentrate all gold and silver are practically in the blister copper, which is cast into anodes. Those copper anodes are electrorefined in an electrolytic system, where the electrolyte is an acid copper sulphate solution, where a high purity electrolytic copper is produced (>999,9/1000). The slime when submitted to an oxidative leaching process, using sodium hypochlorite and hydrogen peroxide as oxidizing agents, turn those metals into solution. This research practical work, apart from concentrating effort on the digestion of the anode slime, aims at evaluating the efficiency of the cementation process of the metals of interest for the separation of them to take place. 141

Jan 1, 2008

By J. L. Liow

Studies have been carried out on the causes and effects of slopping in an annular cylindrical geometry such as the top submerged combustion reactor. Properties of standing waves formed such as the wave profile, period, pressure distribution and velocity have been derived analytically. The wear profile due to wave erosion was calculated based on the assumption of linear motion and that the wear is a dissolution process. The use of the j, factor showed that the wear was proportional to the square root of the wave velocity at any point. Using the dimensions of the lsasmelt reactor given by Errington et al. (1987)[11, the wear profile due to wave erosion was calculated using the analytical solution. The wear profile calculated was shown to have a maximum just below the initial bath surface. The wear was found to be concentrated in the region where the first asymmetric standing wave was most active. The results showed that the refractory near the bath surface will be affected by wave erosion, more so than any other parts of the reactor. The contribution of wave erosion on wear must be accounted for in assessing the total refractory wear of a vessel in which slopping exists.

Jan 1, 1991

By M. C. Ruiz

The conventional pyrometallurgical methods to treat copper sulfide concentrates include generally, one or more oxidizing steps where the formation of SO2 gas can not be prevented. From the economical point of view and the nature of some of the processes in which SO2 is produced, its complete capture is not feasible; therefore an important fraction is released to the atmosphere as fugitive emissions. In this research, the reduction of chalcocite was studied in the presence of lime as an alternative method, which overcomes the pollution problems related to SO2 emissions. The effect of temperature, time, concentration of carbon and CaO on the reduction rate were studied. Among these variables, temperature affects most the reduction rate. Conversions over 95 % can be obtained in less that 20 minutes at temperatures over 1000 ° C. The measured partial pressures of the gaseous components indicated that the chalcocite reduction proceeded through the gaseous intermediate species CO, C02, and the overall kinetics was controlled by the Boudouard reaction. The kinetic model In(1-X)= kt fits well the experimental data. Apparent activation energy of 3 14 kJ/mol was calculated for the temperature range of 900 0C-1050 °C.

Jan 1, 1999

By Lidong Teng, Seshadri Seetharaman, Aida Abbasalizadeh

0In the present paper, the feasibility of the recovery of dysprosium from spent Nd-Fe- B magnets containing approximately 9 wt% Dy was investigated by using molten salt process. The salt bath consisted of a mixture of NaCl-KCl-LiCl corresponding to the ternary eutectic composition. AlCl3 was used as a chlorinating agent in order to enable an efficient dissolution of metal in the molten salt phase in the salt bath. The metal chloride which is formed as the result of chemical reaction between the metal in magnet and AlCl3, is subsequently subjected to electrolysis in order to be deposited on the cathode. Graphite rods were dipped in the salt bath as electrodes and alumina crucibles were used as the containers for the electrolytic cells.

Jan 1, 2014

By Sergio N. Monteiro

Polymeric matrix composites reinforced with coir fibers are being used in many industrial applications such as automobile interior panels and cushions. These composites have relatively low mechanical strength due to the weak fiber/matrix interface. The objective of the present work was to investigate the effect of a surface alkali treatment of the curaua fiber on the mechanical behavior of polyester composites with different amounts of these fibers. The treatment, also known as mercerization, was performed with distinct concentrations, 0.1 and 10% of NaOH at 1 min and 1 hour, before incorporation of the coir fibers into the polyester composite. The results showed no significant change in comparison to similar untreated coir fiber composites. A microstructure analysis revealed that, in addition to reducing the hydrophilic characteristic of the fiber,the treatment also affects the surface morphology and impairs the fiber/matrix interfacial strength.

Jan 1, 2009

By V. R. Voller

"The World Wide Web (the web) provides a very useful resource for the enhancement of teaching and research dissemination. This paper advocates that researchers take control of this resource and become actively involved in creating web content. Two examples of the use of the web in a materials setting is provided. The first illustrates how a concept quiz for teaching can be developed. The second shows how a materials processing model can be run in real time over the web. The paper closes with a summary of some resources that can be used to create web materials.IntroductionA recent copy of a newspaper advertisement read""Share what you know, learn what you don't""This neat phrase sums up a powerful teaching and research philosophy. In an educational setting a prime motivation for research is to uncover the unknown and venture in directions previously uncharted. The balance to this search for knowledge should be a desire to share that knowledge with others; whether it be with students in the classroom or research colleagues in a wider setting.The .World Wide Web and its associated multi-media software offer a perfect platform for researchers to share their knowledge with an extremely wide sector of the research community. To enable the use of this resource researchers must take the power that the web offers them into their own hands and create products that take maximum advantage of the medium. It is key that researches at the forefront become directly involved, otherwise a potential powerful medium will not realize it's true potential, and colorful products with no core content will proliferate. The object of this paper is to outline two ways in which the web can be used to enhance teaching and research objectives."

Jan 1, 2000

By Yousef Mohassab, Feng Chen, Hong Yong Sohn, Mohamed Elzohiery

The determination of reduction degree in a DR process is sensitive to the total iron in the ore and DRI. An accurate and high throughput analysis method for total iron has been developed. Titration of the solution after tin(II) chloride reduction of ferric ion is a widely used method for iron analysis. However, it is a multistep method that requires many chemical reagents and much time. In this work, an ICP-OES analysis method with higher or equivalent accuracy compared with the titrimetric method was developed. This method has much higher throughput and demands fewer chemical reagents compared with the titrimetric method. In this paper, a comparison of the two methods is presented.

Jan 1, 2016

By Bohumir Jelinek, Sergio Felicelli, Mohsen Eshraghi

"We present a parallel lattice Boltzmann - cellular automaton model of the two-dimensional dendritic growth during solidification of binary alloys. The model incorporates effects of solute and energy transport under melt convection. The parallel performance of the algorithm is assessed. A loss in the parallel efficiency is observed when multiple computational cores per processor are utilized. Excellent strong scaling up to thousands of computing cores is obtained across the nodes of a computer cluster, along with the near-perfect weak scaling up to forty thousand cores. The presented solidification model shows a good scalability up to centimeter size domains, including millions of dendrites.IntroductionLattice Boltzmann method (LBM) is an attractive numerical technique for solving fluid dynamics problems. Its advantages are simple formulation and locality, with locality facilitating parallel implementation. In the present model, interface kinetic is driven by the difference between local actual and local equilibrium liquid composition [1]. The cellular automaton (CA) technique is deployed to track the solid-liquid interface [2]. A serial version of the present LBM-CA model with a small number of dendrites was validated against theoretical and experimental results in the previous publications [3, 4]. In this work, it is the first time that simulations with millions of dendrites were performed, something not possible with the computationally much more costly phasefield method [5].This research effort examines a technique for simulations of millions of dendrites in centimeter size domains, including thermal, convection, and solute redistribution effects. Nearly ideal scaling properties of the model are demonstrated. This extensively large landmark was achieved because of• the CA technique being two orders of magnitude faster than alternative, phase-field methods [5]• highly parallelizable LBM method, convenient for simulations of flow within complex and time dependent boundaries• availability of the powerful NSF Extreme Science and Engineering Discovery Environment (XSEDE) supercomputing resources"

Jan 1, 2013

By T. J. White

Xtaltite is the trade name for a generic technology which exploits the well known insolubility of some minerals, which naturally incorporate toxic waste elements, to consolidate and immobilise a range of inorganic waste products. It is a specific case of synthetic mineral immobilisation technology (SMITE) which is already used to immobilise high level nuclear wastes (HLW. Although HLW is highly toxic, it exists in relatively small volumes, occurs in central facilities and may be stabilised at low waste loading (< 10 wt%). In contrast, heavy metal wastes are of considerable volume, therefore Xtalitite waste forms must routinely accommodate high waste loadings (usually in excess of 30 wt% for a particular toxic oxide or combination of oxides) and be suitable for fabrication in remote locations using relatively simple technology. This paper details the methodology underlying Xtaltite, with particular emphasis given to the interplay between solid state chemistry, durability and economic considerations. Specific reference is made to the treatment of arsenious and mercurial wastes.

Jan 1, 1994

By T. S. Bannos

Section 1417 of the Safe Drinking Water Act Amendments enacted by the O.S. Congress prohibits the use of lead containing solders for potable water systems in new construction or when making repairs. The legislature defines "lead-free" solder as containing less than 0.2% lead. In the development of a new solder it was recognized in addition to the lead free requirement, the alloy should perform as well as the popular 50/50 tin lead solder, both in application and properties. Another objective was to have only nontoxic elements. This led to the development of a 4.0% copper, 0.5% silver and 95.5% tin solder. Review of the merits of other alloy systems and the development of the physical properties along with test data are presented for the lead free tin. rich alloy.

Jan 1, 1990

By Petr Sulovsky, Jaroslava Ledererova, Miroslav Svoboda, Michaela Suchardova

"The thinning resources of natural raw materials necessitate an increased degree of waste material recycling. The building industry offers a range of technologies enabling incorporation of industrial wastes into building materials for construction purposes in an economically acceptable way. Our research is focused on finding the appropriate technologies for specific groups of industrial waste materials (IWM). The studied IWM involve coal combustion residues (CCR), desulphurization products, sludges, metallurgical slags, and various other wastes. Many of them contain increased amounts of toxic elements that can under certain conditions get released. In order to prevent this, each specific IWM requires finding the technology that best ensures the binding of toxic elements in the building matter are fixed for the long term.Introduction The sustainable development of mankind is more than ever viewed as a matter of resources. Many aspects of the switch from a throw-away to a recycling society concern one of the largest consumers of natural resources and producer of greenhouse gases, the building industry. One of the biggest tasks lying before the researchers in the field of building materials is to find substitute or alternative raw materials that would save the thinning reserves of natural resources. The most promising and natural way is to replace the traditional raw materials with rejected and unwanted products of industrial processes, classified as wastes. These of course are not produced with the primary intention of achieving some desired properties. The usage of industrial wastes therefore involves finding the optimal way of usage their existing positive (from the point of view of utilizations) properties and minimizing the impact of their undesired properties, i.e. from the perspective of the considered application."

Jan 1, 2008

By H. Fukushima, T. Ohgai, N. Baba

The electrodeposition behavior of Zn and the morphology of the deposited Zn were studied in electrowinning solutions containing polymer additives such as gelatin and polyethylene glycol (PEG). The cathode potential was shifted in a less noble direction and the polarization resistance for Zn deposition increased with increasing concentrations and molecular weights of both gelatin and PEG added to the electrolytic solutions. However, when the molecular weights of these additives exceeded about lxlO4, the cathode was depolarized and the polarization resistance for Zn deposition decreased with increasing molecular weight. The crystal grain size and the (002) orientation of the deposited Zn became smaller when the concentration and molecular weight of the additives increased, and the cathode was polarized.

Jan 1, 2000

By Claudia Gasparrini

Uranium occurs in a variety of minerals, the more common primary ones of which are uraninite-pitchblende, coffinite and a group known as the complex multiple oxides. Identification and description of the uranium-bearing and associated minerals in ore samples may give a preliminary indication of the potential economic importance of the deposit and may also suggest initial approaches to metal extraction. The present paper reviews the common uranium minerals, describes their manner of occurrence and compares the types of deposits with which they are associated. Methods and techniques for their identification are described and their leaching characteristics discussed.

Jan 1, 1981

By D. M. Hausen

Microscopic point-counting of polished sections, in combination with x-ray diffraction analyses of representative whole rock samples, provides an efficient means to compare the modal mineralogic composition of different rock types. Major gangue minerals, e.g., quartz, feldspars, micas, amphiboles, chlorite, clays, etc., are estimated semiquantitatively by x-ray diffraction techniques, utilizing optimum grind, gridded sample surfaces and a sample spinner during scanning. Opaque to semi-opaque oxide and .sulfide phases are estimated by microscopic "point-count" and "gross-count" scanning. Total mineralogic compositions are calculated and normalized to 100 percent from XRD and microscopic data by computer programming. Comparative mineral analyses for different rock types, as well as quantitative microscopic data for various parameters, including particle and crystal sizes, textures, degree of alteration, paragenesis, etc., provide useful guides in mineral exploration, both in early stages of geologic mapping and later stages of economic evaluation. Several case histories are described.

Jan 1, 1981

By E. O. Stensholt

The Hybinette electrorefining process for production of cathode nickel was in use at Falconbridge Nikkelverk A/S, Norway, until 1975 when conversion to the new chlorine leach process was started. In 1978 the conversion to electrowinning had been completed, but further major improvements to the process have been made up to 1987. After a major expansion program in 1985 - 87 the refinery has a nickel capacity of 54 000 mt Ni/year. The main feed materials to the process are converter matte from the Falconbridge smelter in Sudbury, Ontario, Canada, and from the BCL smelter in Selebi-Phikwe, Botswana. A typical composition of the mixed feed to the refinery is: 40 - 45% Ni, 25 - 30% Cu, 20 - 22% S, 2 - 3% Fe and 1.0 - 1.5% Co. The matte is chlorine-leached in the first process step, nickel being dissolved selectively in a train of leach-cementation tanks. Essentially all copper and sulphur that was present in matte appears in the leach residue as CuS. In 1986 an autoclave treatment stage was added to the process to improve nickel extraction from the leach residue. The resulting strong nickel chloride solution is purified by the process steps (1) precipitation of iron and arsenic, (2) solvent extraction of cobalt and other minor elements and (3) precipitation of lead and the remaining impurities. The nickel solution is then fed to the tankhouse, where various nickel products are produced by electrowinning. The chlorine gas that is produced during the electrolysis is returned directly to the chlorine leaching tanks to dissolve more matte. After stripping from the loaded organic phase and solution purification cobalt is also produced by electrowinning. The copper sulphide leach residue, which contains some nickel, is dead- roasted in fluidized-bed roasters. The sulphur is recovered and sold as sulphuric acid. The calcine is leached in spent copper electrolyte, from which cathode copper is produced by electrowinning. Precious metals and the remaining base metals are recovered from the copper leach residue. The Falconbridge chlorine process is very versatile. It can accept a wide range of impurities in the feed and still produce metals of exceptional purity.

Jan 1, 1988