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By Sepideh Abolghasem, Juan Pablo Casas Rodriguez, Juan Camilo Osorio

Predicting flow stress at high strain-rates is a desirable practice for material behavior characterization. Sub-grain size has shown a huge influence in cutting forces and the workpiece surface finish determination during orthogonal cutting process. Hence, a prediction of flow stress as a function of thermomechanical conditions and sub-grain size is of great important which is studied in this work for OFHC copper. The principal thermomechanical conditions being strain, strain-rate and the accompanying temperature rise are characterized in Plane Strain Machining (PSM) and the resulting microstructure, sub-grain size, is quantified. Material maximum flow stress (a constitutive model) as a function of thermomechanical conditions and sub-grain size is predicted considering a saturated state in microstructure using optimization algorithms for reaching the validated temperature rise based on modified Hahn’s model. Evaluated models suggest a major influence of strain-rate and dislocation in temperature rise estimation and flow stress prediction leading to consideration of mechanical failure phenomenon involved in machining-based manufacturing processes.

Mar 1, 2018

By Oscar Restrepo, Juan C. Nino, Henry A. Colorado

New and extraordinary physical-chemical properties of materials at nanoscale open up new applications for the building and infrastructure industry such as structural reinforcements, electronic properties and energy harvesting. Therefore the issues and risks associated with the manufacturing of nanomaterials are now of big concern due to the large volumes and typical processing involved in this industry. This paper presents a discussion and selected applications of nanotechnology in the construction and building materials: from metals and alloys, clay and minerals, ceramics, cement and concrete, asphalt, wood and composites, to finishing systems and some of the most used characterization techniques. Besides the progress in some areas, nanotechnology is just emerging in this field, with many challenges and opportunities, problems unsolved and business opportunities. A discussion regarding the potential health issues and risks of using nanomaterials for workers and the potential environment effects is included as well. New images and diagrams are presented and discussed.

Mar 1, 2018

By C. G. Bastos Andrade, F. R. Valenzuela Diaz, S. M. Toffoli

The climate change observed in the last decades, the increase of global warming, the melting of the polar ice caps, and the sea level rise have in common the non-sustainable development as causative agent. Different nations have mobilized joint efforts with the objectives of minimizing the impact of greenhouse gas (GHG) emissions, investing in the research and the development of new technologies in recycling, in biomaterials, environmentally friendly processes, and new fuel alternatives. This paper evaluates the efficiency of a Brazilian bentonite modified by acid attack, in the purification step of a waste oil to be used for biofuel production, that is, diesel from waste cooking oil (WCO). The following characterization test swere performed: XRD, CEC, XRF, SEM/EDS, specific surface area (BET), stereomicrography, kinematic viscosity, and spectrophotometry at 440 nm. The modified bentonite exhibited good purification capacity for WCO when compared to a commercial product.

Mar 1, 2018

By Monica M. Jimenez Correa, Jorge A. Soares Tenorio, Denise Crocce Romano Espinosa, Paula Aliprandini

The surface zone of nickel laterite ore is generally considered as residue. However, because of the depletion of ore sources and the increase in demand, this previously discarded zone may now be processed economically for nickel and cobalt. After leaching and removal of the impurities, the solution contains cobalt, magnesium, manganese and nickel. Solvent extraction is a hydrometallurgical technique used in the separation of metals from aqueous solutions. Cyanex 272 and D2EHPA are extractants used to separate nickel from cobalt. The mixture of extractants can change the performance during the metals extraction. This work aims to evaluate the solvent extraction of nickel and cobalt when Cyanex 272 and D2EHPA are mixed. The results showed that the increased concentration of D2EHPA in the organic phase increased the extraction of nickel and magnesium. However, cobalt extraction was reduced and the manganese extraction was not altered.

Mar 1, 2018

By Muhammad A. Imam, Ramana G. Reddy

This study provides a reasonable evaluation of the Mg-B binary system. Magnesium and Boron (Mg-B) alloys were investigated to determine their thermodynamic properties employing solid state electrochemical cells based on CaF2 electrolyte represented as –Pt; Ar= MgþCaMgF4 f gCaF2 k kf½Mg B alloy þ CaMgF4 g=Ar; Pt+ Investigations were performed over the temperature range of 773–873 K to measure the electromotive force (EMF), which was used to derive the partial Gibbs Free energies of the alloys in the composition range of XB = 0.07 to 0.95. The activities of Mg were also calculated from partial Gibbs Free energies. The activities of Mg in MgB2, MgB4, and MgB7 were expressed as a function of temperature respectively, ln aMg = 4.27–9.32 × 103/T, ln aMg = −7.54 + 6.67×103/T, and ln aMg = 4.93–19.57 × 103/T, where T is the temperature in K. From this expression, the activity of Mg for these intermediate phases can be extrapolated at a higher temperature to get the accurate phase boundaries for the Mg-B system.

Mar 1, 2017

By Laura Angeles, Martin Reyes, Ivan Reyes, Miguel Perez, Francisco Patiño, Mizraim Flores, Elia Palacios

Chemical and mineralogical characterization of a sulphide ore from the mining district of Zimapan, Hidalgo, Mexico, was performed in order to obtain accurate information on the composition of the ore to optimize the subsequent flotation process. A combination of techniques was used: Scanning Electron Microscopy (SEM) with Energy Dispersive Spectrometer (EDS), X-ray diffractometry (XRD), Inductively Coupled Plasma (ICP) and Fourier transform infrared spectroscopy (FTIR). The SEM mapping confirmed the presence of the elements: Ca, Si, Fe, K, S, Al, Zn, Mg and Mn. The XRD analysis suggests that the ore matrix is calcite; additional species found were wollastonite, johannsenite, and pyrite, among other impurities. The FTIR analysis performed for the aqua regia insoluble showed the presence of calcium oxide, copper oxide and silicon oxide. The results for the ICP analysis were:13.31% S, 2.55% Fe, 0.46% Zn, 0.03% Cu, 0.06% Pb, 0.07% Mn, 0.09% As, 0.01% Sb and 0.08 grton-1 Ag.

Mar 1, 2017

By S. L. I. Chan, M. Z. Quadir, D. C. Austin, P. J. Hazell, A. Chen, A. A. H. Ameri, D. East, J. P. Escobedo, M. A. Bevan, A. D. Brown

The microstructure and mechanical response of additive manufactured Ti64 under compression and tension has been investigated. Quasi-static and dynamic experiments were conducted on electron beam powder bed Arcam A1 (EBM) and blown powder laser Optomec LENS MR-7 (LMD) additive manufactured specimens. Hot isostatic pressing (HIP) was conducted on both of the additive manufactured specimens and results were compared with as-received specimens. Digital image correlation (DIC) was utilized to observe the in situ development of deformation fields during tensile loading. Optical microscopy was conducted on pristine and deformed specimens to examine the microstructure of the specimens. HIP treatment reduced the porosity by *90% with a concomitant increase in hardness by 40%. The results from tensile experiments show that additive manufactured Ti64 display a higher values for the yield stress, hardness, and ultimate tensile strength than conventionally manufactured Ti64. Under quasi-static compression, it was observed that EBM specimens exhibit a higher yield strength and ultimate tensile strength than LMD specimens.

Mar 1, 2017

By L. I. C. Fernandez, E. B. Ferreira Filho, L. G. Pedroti, L. G. Justino, W. E. H. Fernandes, R. C. S. S. Alvarenga

More and more industries have been concerned with the disposal of the wastes generated in their production processes, once this generates a positive impact, both visual and economic enterprise, no more needing to have resources for transport and final disposal of wastes. In this context, and seen the importance of the Portland cement a sa building material, which aims the creation of an ecological cement from the mix of two wastes, the grits, which is a waste generated in pulp production, and the granite beneficiation waste. It proceeded initially with the chemical and physical descriptions of the wastes. Five mixtures, varying the percentages of the wastes and the preparation method of the raw materials, were prepared. After,the blends were sintered in a muffle furnace at 1300 °C for 15 min, forming new compounds that were compared with national cements, according to the Brazilian technical standards. It was concluded that the sintering of the product obtained satisfactory results, presenting good binder characteristics, however, some parameters were outside the limits for common Portland cements such as rapid setting time, large expandability and low compressive strength.

Mar 1, 2017

By Muammer Kaya

This paper reviews the existing and state of art knowledge for electronic waste (e-waste) recycling. Electrical/electronic equipments (EEEs) which are unwanted, broken or discarded by their original users are known as e-waste. The main purpose of this study is to provide a review of e-waste problem, give e-waste management strategies and introduce various physical e-waste recycling processes with special attention towards extraction of both metallic values and nonmetallic substances. The hazards arise from the presence of heavy metals (e.g. Hg, Cd, Pb etc.), brominated flame retardants (BFRs) and other potentially harmful substances in e-waste. Due to the presence of these substances, e-waste is generally considered as hazardous waste and may pose significant human and environmental health risks if improperly managed. This review paper describes the potential hazards and economic opportunities of e-waste. First of all, an overview of e-waste/printed circuit board (PCB) components and substances are given. Current status and future perspectives of e-waste and waste PCB recycling techniques are described. E-waste characterization, dismantling, liberation, classification and separation processes, are also covered. Manual selective dismantling after desoldering and metal-nonmetal liberation at −150 μm with two step crushing are seen to be the best techniques. After size reduction, mainly physical separation processes employing gravity, electrostatic, magnetic separators etc., which are commonly used in mineral processing, have been critically reviewed here for separation of metals and nonmetals. The recovery of pure metals from e-waste after physical separation can be performed by pyrometallurgical, hydrometallurgical or biohydro metallurgical routes, which are not covered here. Suitable PCB recycling flowsheets for industrial applications are also given. E-waste recycling will be a very important sector in the near future from economic and environmental perspectives for both developing and developed countries. Recycling technology aims to take today’s waste and turn it into conflict-free, sustainable polymetallic secondary resources (i.e. Urban Mining) for tomorrow. Recycling technology must ensure that e-waste is processed in an environmentally friendly manner, with high metal/nonmetal recovery efficiency a lowered carbon footprint. Taking into consideration our depleting natural resources, this Urban Mining approach offers quite a few benefits; it provides a substantial secondary resource, while also ensuring that the environment is kept free from harmful toxins in e-waste. This results in increased energy efficiency and lowers demand for mining of new raw materials.

Mar 1, 2017

By D. C. Austin, P. J. Hazell, A. A. H. Ameri, J. P. Escobedo-Diaz, D. East, M. A. Bevan, A. D. Brown

Additive Manufacturing (AM) has become increasingly popular due to the ability to produce components with complex geometries and properties. The efficiency of this manufacturing method is investigated in this paper by examining the mechanical performance of AM austenitic stainless steel 316L under different strain rates. Dynamic compression experiments were conducted by using a Split Hopkinson Pressure Bar (SHPB). Microstructural observations were performed by utilizing optical microscopy. The behavior of this material is compared against stainless steel 316L manufactured by conventional methods. The results show that theAM316L used in this study display a considerable difference in the mechanical properties compared with conventional stainless steel alloys.

Mar 1, 2017

By Sheng-li Wu, Guo-liang Zhang, Bo Su

One of the major challenges for the Canadian Gen IV Super-Critical Water-cooled Reactor (SCWR) concept is the selection of fuel cladding materials. The Canadian SCWR concept will operate at a core outlet temperature of 625 oC and 25 MPa of pressure with peak cladding temperature reaching as high as 800 oC. Corrosion resistance is an important factor for material selection. Austenitic stainless steels that contain Cr contents greater than 18 wt.% are generally considered to provide adequate corrosion resistance. In this work, the pressure dependence of the corrosion of austenitic stainless steel 310 containing 24 wt% Cr is assessed at 625 C for exposures of 1000 hours to evaluate the suitability of superheated steam as a surrogate for supercritical water at 25 MPa. Transmission Electron Microscopy (TEM) revealed that 310 exposed to different pressure conditions at 625 oC. (i.e., 0.1, 8 and 29 MPa) had generally the same type of the oxide structure, i.e., a Cr-rich oxide with the spinel structure on outer surface adjacent to the water phase. The material exposed at 8 and 29 MPa had a double layer oxide structure, with the outer oxide layer having a much larger grain size, while the samples exposed at 0.1 MPa showed only a single spinel-phase oxide layer. Cr-depleted recrystallized austenite grains were found underneath the spinel phase oxide. The adjacent large-grained austenite substrate had M23C6 carbides in the grain interior. The implications of these results are discussed.

Jan 1, 2015

By S. Yin, A. Bogno, H. Henein, P. Natzke

Impulse Atomization (IA) (a single fluid atomization technique) was used to rapidly solidify Al- 4.5wt%Cu and Al-4.5wt%Cu-0.4wt%Sc under argon atmosphere. In addition to the IA-generated droplets, the same technique was used to produce strips by Spray Deposition (SD) of the same alloys on a copper substrate with and without oil coating. The rapid solidification microstructures were analyzed using Scanning Electron Microscopy (SEM). From the SEM images, the amount of eutectic and the secondary dendrite arm spacing (SDAS) were measured. These SDAS results lead to the estimation of cooling rate. The eutectic fraction coupled with the metastable extension of the solidus and liquidus lines of Al-Cu (Sc) phase diagram lead to the estimation of primary and eutectic undercoolings. A comparison of the solidification path of the droplets and the strips was done as well as the analysis of the effects of scandium.

Jan 1, 2015

By Kunwar Pal, S. K. Tyagi, A. K. Pandey

"This study deals with the performance evaluation, technical and environmental aspects of different cookstove models (NIRE-02, NIRE-03 & NIRE-04). These cookstove models were designed, fabricated and evaluated following Bureau of Indian Standards (BIS) and their performance was compared from technical and environmental points of views. The theoretical efficiencies of all the cookstove models are found to be in good agreement with the experimental one. Also, the overall performance of these models is found to be in the order of (NIRE-04 > NIRE-03 > NIRE-02) which is also observed to be much better than that of the traditional cookstoves being used by the people in most of the developing countries around the world. The CO2 emission reduction from these models is found to be between 2.0-3.0 tons per household annually which is ultimately in good agreement with the experimental values.IntroductionMore than 2.5 billion people around the world depends on the biomass based resources for cooking and heating applications which includes wood, cattle dung, charcoal and agriculture residue [1,2]. Generally, people of rural area cook their food on unvented open fire, which burn biomass fuel inefficiently besides it creates many thermal and environment pollution hazardous causing health problems in the women and girl children due to more exposure of emissions. Also the consumption of biomass is very high as compared to the fossil fuels due to the fact that the large population of the developing countries lives in the rural area than that of in the urban area. It is estimated that about 3% of the diseases are caused due to incomplete combustion of biomass, which results in the around 1.8 million premature death every year including around 0.9 million death under five year of their age [3,4].Ramanathan and Carmichael [5] recently found that the black carbon of unburned smoke is playing a major role in global warming. The emission factors for different combinations of fuel and stove tested in China for direct and indirect GHGs as well as other airborne pollutants such as, CO2, CO, CH4, TNMHC, N2O, SOx, NOx, TSP etc. for a typical set of operating parameters [6]. The improved biomass cookstove technology came into assistance which is technically feasible, socially reliable and economically viable [7, 8]. The improved biomass cookstove not only reduces pressure on the biomass resource, but also reduces the environmental pollution and also minimize the time required for collection of fuel wood [9, 10]. Sharma et al. [11] emphasized on the adoption and large-scale propagation of efficient stoves to improve the health of rural women and to reduce the consumption of firewood and environmental pollution."

Jan 1, 2014

By Gavin Lind

The Minerals Council of Australia (MCA), through its Minerals Tertiary Education Council (MTEC), builds capacity in higher education in the core disciplines of mining engineering, metallurgy and minerals geoscience. Over the past fourteen years, this all-of-industry approach in securing the long-term supply of these critical skills (which remain a chronic skills shortage for the Australian minerals industry) through nationally collaborative programs across sixteen Australian universities delivers spectacular and sustainable results for the industry. These unique, world-first programs are built on a healthy platform of dedicated industry funding and in-kind support and forms part of the MCA’s broader uninterrupted, sustainable education and training pathway to increase workforce participation, workforce diversity and workforce skills, regardless of the business cycle in the industry. This paper will highlight the origins, iterations and current successful programs of MTEC, including its future vision, and presents a mechanism for industry and academia to collaborate to address future professional skills needs in the minerals industry globally.

Jan 1, 2014

By Evgenii Pavlov, Ivan Tronin, Viktor Timofeev, Vladimir Kislov, Sergei Bogovalov

"Modeling of the magnetohydrodynamical (MHD) and thermodynamical processes during the industrial scale Direct Chill (DC) casting of aluminum slabs is performed using a combination of ANSYS/CFX and ANSYS/EMAG software. The electromagnetic field is modeled through ANSYS/EMAG, while hydrodynamic and thermodynamic processes are modeled through ANSYS/CFX. Both packages were modified in order to calculate MHD flows in the liquid pool that forms during aluminum DC casting, and they were unified into a software combination that provides simultaneous simulation of all the above processes. The simulation shows that the electromagnetic stirring of the molten aluminum changes the shape of the solidification front (solid-liquid interface) very dramatically, namely it becomes significantly flatter. This effect should improve the internal structure of aluminum DC slabs and allows us to increase the casting velocity.IntroductionProduction of Aluminum alloys with high mechanical properties and structural uniformity is one of the main goals of industry. The preferred production method of aluminum alloys in most modern plants is Direct Chill (hereafter DC) casting because it offers high productivity and commercial success. One important limitation of this technology is the development of centerline shrinkage in slabs larger than about 1 meter. The improvement of the internal structure of long DC cast slabs can be achieved by electromagnetic stirring (hereafter ES) of the liquid metal above the solidification front. This intensifies heat transport in the zone close to the solidification front and suppresses shrinkage formation."

Jan 1, 2013

By Marcelo Mourao, Adolfo Pillihuaman, Alberto Nogueira, Cyro Takano

"The self-reduction is an alternative and promising process for production of pig iron because offers decisive benefits such as enhancing the reaction kinetic with decrease in fuel consumption and C02 emissions. The self-reduction mixture of iron ore fines, carbonaceous reducer and additives for slag forming components, without agglomeration, was tested in a laboratory rotary kiln. The additives for slag were defined for presenting two different estimated liquidus temperatures (1623 Kand 1773 K) to verify the effect of these temperatures on the iron-carbon nuggets coalescence process. These mixtures were tested at 1673 and 1773 Kin an experimental rotary kiln. After reduction-melting and coalescence processes the samples were disaggregated and the iron nuggets were classified by size. It was considered that nuggets larger than 7,93mm would be a good reference for coalescence index. Low liquidus temperature slag presented 37% of this larger fraction against only 13.5% for high liquidus temperature one. The low liquidus temperature slag would facilitate contact between the particles of iron-carbon in a rotary kiln, enhancing the coalescence.IntroductionThe slag composition usually depends on the reducer ash composition, the ore gangue, the binder composition and any fluxing material [l], and the mechanism of carbon transportation in slag that contains iron oxide reducible by carbon can be explained by the oxide reduction and the metal carburization. During carbon transportation, the carburized particle is transported to slag-metal interphases by the gravity effect, being assimilated by the metallic phase [2]. When the slag's iron oxide comes in contact with the solid carbon, it is immediately reduced, forming Fe particles and CO bubbles as it is shown in the figure l(a). The Fe particles are carburized by carbon particles; they are liquefied simultaneously in the carbon-slag interphase. The Fe-C liquid particles are transported from the slag-carbon interphase to iron-slag interphase as a result of slag flow, based on the surface tension difference (Marangoni effect), figure l(b). The Fe-C liquid particles coalesce on the iron surface and the carbon is immediately diffused in the iron as it is shown in figure l(c). The reduced iron is carburized continuously by repeated sequences [3]."

Jan 1, 2013

By Mohamad Omarei, S. M. Sadrameli

"The aim of this research work was to produce biodiesel (fatty acid methyl esters, FAME) from canola oil using KOH loaded on y-Al203 support as a heterogeneous catalyst. Different parameters such as effects of the molar ratio of methanol to oil, catalyst amount and reaction time on the yield were investigated. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used for characterization of the catalysts. A biodiesel yield of 86.67% was obtained under catalyst preparation and transesterification conditions of calcinations temperature of 773 K, 4 h of reaction time at 338 K, and using 3.5 wt% catalysts and molar ratio of methanol/oil of 15:1. The leaching of potassium species in the spent catalyst was observed.1. IntroductionBiodiesel is an eco-friendly and alternative energy source for diesel engines that can be synthesized by transesterfication of vegetable oil or animal fat with alcohols [1 ]. There are four principal approaches to the synthesis of biodiesel involving the transesterification of the triglycerides of the plant oils and animal fats: base catalysis [2], acid catalysis [3-5], employing supercritical alcohol conditions [6] and enzyme catalysis [7]. The commonly used homogeneous catalysts are NaOH, KOH and their alkoxides. Homogeneous alkali-catalyzed transesterification is much faster than acidcatalyzed transesterfication [8]. However, a large amount of water is required to transfer the catalysts from the organic phase to a water phase after the reaction. Therefore, it is considerably more costly to separate the catalyst from the produced solution [9]. These disadvantages could be removed by use of a heterogeneous catalyst [10]. The use of heterogeneous catalysts eliminates the neutralization step, hence it results much easier to separate from liquid products. Also, they can be designed to give a higher activity and selectivity and to have longer catalyst lifetimes [11]. A large number of different heterogeneous catalysts have been synthesized for biodiesel production. For example, calcined Mg-Al hydrotalcites [12], zeolite and metal catalysts [13], metal oxides such as calcium oxide (CaO) [14], magnesium oxide (MgO) [15], zirconium oxide (Zr02) [16], and supported catalysts [17] have been investigated as heterogeneous catalysts. CaO and MgO are most frequently used heterogeneous catalysts for biodiesel production [18]. In this present work, we aimed at developing an efficient catalyst for transesterification of canola oil. We have prepared KOH/ Al203 by impregnation and applied to determine the optimum conditions for biodiesel production. Three different variables including reaction time , alcohol to oil molar ratio and catalyst loading with may influence the quality of the produced biodiesel were optimized. Moreover, SEM (scan electron microscope), XRD (X-ray diffraction) and XRF were used for characterization of the catalysts."

Jan 1, 2012

By Jian Li, J. Miles, P. Liu, W. Cook, W. Zheng, Alvin Qian

"High temperature corrosion resistance is one of the key challenges in water-cooled nuclear reactor material development. Iron based materials with low Cr content exhibits superior high temperature mechanical properties. However, due to the relatively low Cr content, their corrosion resistances under supercritical water (SCW) conditions are generally poor. High-Cr alloys, despite their much improved corrosion resistance, often suffer from embitterment due to the precipitation of sigma phase in the microstructure. In this study, corrosion resistance of an in-house produced high Cr steel (25%Cr) showed much better corrosion resistance compared to that of low Cr alloy (14%Cr). This high-Cr steel can potentially be used as a corrosion-resistant coating for structural materials in sew applications.INTRODUCTIONThe supercritical water-cooled reactor (SCWR) concept is one of the promising designs for the next generation nuclear reactor, in which the water coolant is designed to be at about 625°C and 25 MPa at the outlet of the reactor core. Under these relatively high-temperature and high-pressure conditions, the cooling water is at supercritical state. High-temperature mechanical properties, corrosion resistance and radiation damage are some of the key challenges. At present, no single commercial material can meet all the requirements of the severe SCWR in-core conditions. Canada supports research in several key areas of SCWR development, including materials selection. A major focus is on materials development, selection and evaluation for both in-core and out-of-core components.Allen et. al. [1] carried out a comprehensive study on the SCW corrosion resistance up to 600 °C on commercially available high temperature materials including Ni-based super alloys, various types of stainless steels and ferritic/matensitic steels. They concluded that ferritic steels develop a relatively thick but mechanically stable oxide layer, while austenitic alloys develop a thinner oxide layer that has been found to spall in some cases. Of the three types of alloys examined, the Ni-based alloys exhibited the lowest oxide thickness, however pitting was observed in the vicinity of intermetallic precipitates."

Jan 1, 2011

By Graham Cooke, Abhishek Lahiri, Animesh Jha, E. Jeya Kumari

"CO2 reduction by alternative energy devices such as wind-power, electric vehicles utilize rare-earth elements (REE) in several forms; such as in piezo-electric devices, batteries and magnetic materials. In 2010, the 95% of Rare Earth supply is controlled by China, compared to USA being dominant supplier in the 1980s. The dependence upon a single source of lanthanides has prompted the utilization of lower grades of titaniferous mineral concentrates, which often have rich seams of REE. We propose a new methodology, which utilizes the low-grade minerals for the extraction of synthetic rutile and also significant quantities of REE. We demonstrate the alkali roasting of lower grades of mineral concentrates and subsequent leaching in an aqueous medium for preferential flocculation of REE during the extraction of synthetic rutile. Changes in mineral structure during alkali roasting and leaching determine flocculation of REE and permit their separation at the front end of unit process.The physical chemistry and crystal structure of minerals in equilibrium with alkali and aqueous medium play an important role, which we explain by demonstrating the changes in the crystal structure. The quantification of separation of RE oxide via chemical analysis suggests that it may be possible to separate rare-earth oxides between 50 and 80% of the initial concentration in the non-magnetic fractions of ilmenite, for example. The microstructural and X-ray diffraction analysis points out that the presence of alumina and roasting with potassium based alkali enhances the separation and flocculation of rare-earth elements at the front end of the process after roasting. The process allows the recovery of CO2 generated by recycling into the process for the regeneration of alkali."

Jan 1, 2011

By Jorge A. S. Tenorio, Chuanwei Zhuo, Joner O. Alves, Yiannis A. Levendis

"Reduction of combustion-emitted greenhouse gases, which are associated with global warming, may be achieved by use of CO2-neutral alternative fuels, such as bio-ethanol. Distillers Dried Grains with Solubles (DDGS) are the main co-products of the com-grain-based ethanol industries. In 2009, the North American production of ethanol from com was about 38 billion liters, which generated approximately 31.5 million tons of DDGS. Samples of DDGS were pyrolysed at temperatures of 600-1000 °C in a two-stage laminar-flow horizontal furnace, and a catalyst system was used to synthesize nanomaterials. This work presents a microstructural characterization of these nanomaterials by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results showed that the nanomaterials produced from pyrolysis of DDGS were in the form of long, entangled, rope-like structures with rugged walls, lengths in the tens of microns, and axially non-uniform diameters in the range of 100-300 nm.IntroductionThe interest in ethanol has increased considerably worldwide due to the necessity of finding renewable and cleaner energy resources [1, 2]. According to the Renewable Fuels Association (RF A), the world ethanol production in 2008 was approximately 65.7 billion liters (17.3 billion gallons), which figure represented a 24% increase in the production over that in the previous year [3]. The major producers of ethanol are the USA and Brazil, which together account for 90% of world production. The main feedstock for ethanol in USA is com grain, whereas sugarcane predominates in Brazil [2-4]."

Jan 1, 2011