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By Luciano B. Oliveira, Angela O. Costa, Sergio N. Monteiro, Luis Guilherme C. Marques

"Biofuels are gaining a relevant role in today’s world not only as a solution for the decreasing petroleum reserves but mainly as a positive contribution to the efforts in global warming mitigation. In Brazil, since 1975, the replacement of gasoline by ethanol started a so-called PROALCHOOOL program, which is now being complemented with the replacement of petroleum diesel by biodiesel. This biodiesel program was officially created in 2005 with mandatory goals, supported by legislation, of 2% addition in 2008 and 5% addition in 2013 into all commercialized regular diesel. In this work, a critical analysis of the Brazilian biodiesel program is presented. The technical aspects related to the different raw materials, including wastes, available for biodiesel conversion as well as the economical conditions associated with production costs and market logistic are discussed. The environmental benefits associated with the retention of greenhouse gases are also discussed.IntroductionToday the commonly accepted fact that the petroleum world reserves are probably passing through a maximum and start declining in terms of the total amount that can be extracted by existing technologies is motivating significant changes in our society. The continuous increase in the price of gasoline and other liquid fuels is an immediate worrisome and visible consequence. However, more than an economical problem, our civilization is already facing the effects of global warming, due to CO2 emission from burning fossil fuels, mainly from coal and petroleum. It is now realized that a large scale solution for these problems demands the prompt substitution of non-renewable fossil fuels by others that, in addition of being renewable, have a relatively lower contribution to the greenhouse gases."

Jan 1, 2008

By Brian Cochran, C. Edward Eckert

"EXECUTIVE SUMMARYINTRODUCTIONThe commercial incentives for using molten aluminum in casting operations are numerous and substantial. Although these incentives apply broadly to both shape castings (foundry) operations and wrought alloy production, the merit of a particular motive is indeed downstream processing sensitive. Melting cost reduction is a universal incentive that impacts on essentially all aluminum products. At a natural gas burner cost of $4.50 per therm, for example, the reverberatory furnace energy cost is at least $0.01 per pound of aluminum melted, exclusive of melt loss, fixed costs, and other expenses. The Aluminum Statistical Review' cited 3.188 million metric tons of secondary aluminum that was recovered by the industry in 1995. This represents a re-melt energy cost of over $70 million. Other incentives to use molten secondary aluminum include throughput enhancement, metal chemistry assurances, environmental considerations, and the avoidance of an in-house scrap processing operation.A traditional disincentive to use molten secondary aluminum is metal quality. If a particular secondary processing operation was successful in achieving and preserving an acceptable metal quality level prior to shipment, the subsequent metal transfer and ladle delivery events would frequently obviate these efforts. For example, a metal superheat on the order of several hundred degrees is required for an unheated transfer ladle to travel 3 to 4 hours to a customer location. The rate of the y-alumina formation reaction approximately doubles for every 120°F increase in temperature, therefore, the effect of excess superheat on melt loss and metal quality is considerable. Linear oxidation reactions, such as magnesia formation in magnesium containing alloys, are influenced to an even greater extent by temperature.The typical quality detractor events are:"

Jan 1, 2000

By J. Wendt, P. R. Sahm, T. Uloth, M. Weck, F. Foertsch

"The FEM program systems CASTS (Computer Aided Solidification TechnologieS) (1) and FINELF (FINite ELement Frontal Solver) are used to optimize a thin walled die casting. After a short description of the programs it will be worked out how to use them not only for simulating solidification processes but also for optimizing the design of workpieces. The calculations will be done for an automobile's support bracket which is manufactured in a well known car factory in Stuttgart, FRG.IntroductionAt the Aachen Foundry Institute the software package CASTS was developped to simulate solidification of castings. In order to optimize the whole manufacturing process it does not appear sufficient any more to take into account only the specific aspects of casting. For instance one has to consider additionally the stress situation under service load. For this reason the Foundry Institute together with the Aachen WZL-Institute (Machine Tool Laboratory) and the car factory mentioned above started to probe into a first step in that direction. Figure 1 shows the support bracket which shall be optimized."

Jan 1, 1986

By Cong Wang, Kexin Jiao, Yongan Zhao, Haibin Zuo, Jianliang Zhang

Traditional refractory materials for blast furnace hearth lining are mainly composed of carbon bricks and the ceramic cup. However, these materials can’t meet the demands for long service life design of blast furnaces. In this paper, a new refractory called carbon composite brick (CCB) was introduced, which combined the advantages of carbon bricks and the ceramic cup. In this case, the resistance of the CCB against corrosion was equal to the ceramic cup and the thermal conductivity of the CCB was equal to carbon bricks. From the results of more than 20 blast furnaces, the CCB could be well used in small blast furnaces and large blast furnaces. In the bad condition of low grade burden and high smelting intensity, the CCB gave full play to the role of cooling system, and effectively resisted the erosion of hot metal to improve the service life of blast furnaces.

Jan 1, 2015

By C. Anderson

Most applications of copper metallurgy are geared towards primary production. However, as recycling of materials is a growing industry, one future facility will rely on copper metallurgy as a means of processing precious metals. This paper will discuss the derivation of the proposed copper pyrometallurgical and electrometallurgical unit operations to be utilized in industrial recycling of secondary precious metals.

Jan 1, 1999

By Ahmet Geveci

[Generally accepted formula related to sulfur slag-metal distribution ratio is given by the following equation: [ ] According to the above equation it can be deduced that sulfur distribution between slag and metal is governed mainly by metal composition (?s term), slag composition (slag basicity and in turn sulfide capacity), oxygen potential of the system (ao¬¬ term) and temperature(related to equilibrium constant, K). In this study, the results of ladle furnace operations conducted in Erdemir-Iron and Steel Works Co. (Turkey) in relation to sulfur removal, have been given. Typical ladle furnace slag analyses of 4937K quality steel have been presented. Activity coefficient of FetO,?FetO, have been calculated with the relation obtained fromthe literature. Activity calculations have been performed with the program written in Mathcad. The changes in activity of aFetO in the slag phase,, have also been studied in relation to the sulfur removal: The relation between % Decrease aFetO and %DeS (measured)have been investigated for 4937K runs and someother types of steel produced in the Erdemir Plant. Related to ladle operations %desulfurization defined as [(%Sinitial-%Sfinal)/S%initial]*100 values have been presented for different steel qualities.]

Jan 1, 2006

By M. K. Alam

Chemical Vapor Deposition (CVD) processes are currently attracting special attention in materials processing. CVD processes are now used to produce special materials in the form of thin films, coatings, composites, and optical fibers. This process produces material of high purity, in complex shapes, and in a variety of microstructures. It is a capital intensive process, involving use of high cost raw materials. Modeling simulations have the potential of reducing the time for CVD . process design, and the need for experimentation. Modeling would, therefore, appear to be an attractive option for producing a product of acceptable quality. At Ohio University, progress has been made in modeling of CVD processes, specially in the areas of optical fiber preform fabrication, and fiber coating.

Jan 1, 1990

By T. Inami

The chlorine leach of the anode slime was studied in order to improve the treatment process at the Niihama Nickel Refinery. The anode slime originates from the nickel matte electrorefining and, contains 3-5% of nickel as sulfides. A comparative study has been conducted on the filter cake resulting from the sulfur filtration of the molten anode slime. The kinetic factors of the chlorine leach such as temperature, grain size were defined. Under the optimized condition, 70-80% of the nickel is recovered from the slime or filter cake. On the basis of these results, the chlorine leach process for the treatment of anode slime has been established. The leaching plant has been installed and successfully operated since 1986.

Jan 1, 1988

By John K. Wright

The segregation process involves heating oxide-type ores with a halide salt in the presence of a solid reductant. By a complex series of cyclic vapour-phase reactions, the desired metal is extracted from its original position in the ore and segregated to the vicinity of the reductant. In this form it is then amenable to concentration by physical methods. In this work the segregation behaviour or eight different nickel laterite ores has been examined using a laboratory rotary kiln. It was found that the silicate (serpentine) ores responded better to the segregation conditions used than did the limonitic ores. An examination of the segregated metal particles showed that they consisted of ferro-nickel. The concentration of nickel in the metallics was sensitive to the ore types and the segregation roasting conditions.

Jan 1, 1994

By S. Uddin

An integrated device has been developed to measure sedimentation potential, conductivity and pH simultaneously of particulate systems. Maxwell?s model was used to calculate volume fraction of solid from the conductivity data. In this approach, all system variables are known and zeta potential can be calculated from Smoluchowski?s equation. The technique is validated by comparing zeta potential vs. pH for alumina and silica suspensions with electrophoresis measurements. The technique was extended to mixed alumina/silica systems. Sufficient column height along with size difference between the two minerals allowed gravity fractionation during settling. Sedimentation potential measured over time identified the transition from one mineral to the next. Using XRD analysis the results supported the correlation between surface charge and sample composition. This is a step towards characterizing surface charge of mixed systems of interest in mineral processing.

Jan 1, 2010

By N. Kanari

Chalcopyrite concentrates and their pure constituents were chlorinated by C12+N2 between 25 °C and 750 °C. The reaction products were analyzed by SEM, XRD and chemical analysis. The effect of gas flow rate and chlorine content of the gas mixture on the reaction rate were investigated. At room temperature, these solids start to react with chlorine giving metal and sulfur chlorides. Complete reaction is achieved at about 300 °C and the iron and sulfur chlorides were fully volatilized. The chlorination residue is composed of valuable metals' chlorides. A simplified flow - sheet for the treatment of chalcopyrite concentrates by chlorine was suggested.

Jan 1, 1998

By C. Hecker, J. A. Garcia

To determine the kinetic reaction mechanism, electrochemical experimental techniques of stationary polarization, linear voltammetry and faradaic impedance were used. Gold electrodeposition experiments were realized using an electrolysis cell, provided· by a rotary disk of vitreous carbon and or' platinum counter electrode of platinum mesh and reference electrode. Using an automatic measurement system voltarnmograrns and Nyquist faradaic impedance spectra were obtained. In this paper, responses for different cases were analyzed through faradaic impedance criteria, considering several kinds of diagrams obtained. The importance diffusion influence of aurocyanide ions and adsorption as controlling steps previous charge transfer was verified. A model of proposed mechanism is discussed.

Jan 1, 1997

By Tiebao Yang

In high pressure die casting processes, a die plays a critical role in removing heat from the molten metal during the cavity filling and solidification stages. Proper control of die temperature is essential for producing superior quality components and yielding high production rates. This paper proposes a local temperature control scheme for die thermal management based on a computerized intelligent real-time monitoring and control system (IRMCS). In this scheme, cooling water lines are controlled by a pump and solenoid valves. A controller is designed according to the law of die temperature fluctuations. The results obtained from the experiments carried out on a laboratory die casting process simulator indicate that the controller can limit the local die insert temperatures in a given band. Hence, the desired thermal pattern of the die insert becomes achievable.

Jan 1, 2006

By Alana Pereira Ramos, Walman Benicio de Castro

Amorphization and martensitic transformation (Ms) characteristics of Ti–Ni-Cu alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray diffraction. In these experiments particular attention has been paid to change the wheel linear velocity from 21 to 63 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate and alloy composition on martensitic transformation behavior is discussed.

Jan 1, 2015

By N. L. Piret, E. N. Mounsey

Ausmelt technology is successfully used to process primary and secondary materials to produce lead in large-scale commercial operations and to meet stringent environmental standards. The development and commercial data covering these applications and the results with respect to metallurgical, cost and environmental performance are reviewed in commercial operations. A new smelter is scheduled for commissioning in 2000 at Korea Zinc's Onsan site to process lead fume and other secondary materials to produce 50,000 tonnes per annum of lead bullion. The unique features of Ausmelt technology also allow for the efficient processing of polymetallic concentrates and secondary materials, particularly copper and lead, through the effective separation of these elements into metal, slag and fume species. This capability has been successfully demonstrated at a commercial scale and the results and implications for the industry are discussed.

Jan 1, 2000

By Xi-Shan Li, Qian Li, Yong-bin Yang, Li-na Cui, Tao Jiang, Jie Ge

"With regard to control environment pollution in the roasting pretreatment of sulfur & arsenic-bearing gold concentrate, roasting of double-layered pellet was proposed. In the paper, the characteristics of double-layered pellet roasting were studied. Removal and solidification rates of sulfur and arsenic were investigated as primary factors. The result indicated that the removal and solidification rates of arsenic reached up to 95.91 % and 98.95% while the sulfur was 97.19% and 97.90% respectively on the premise of adopting slaked lime as solidified agent at temperature of 6000, the package proportion of 2.14 and roasting time of 3h. However, pyrite and arsenopyrite were transformed to hematite and magnetite and product of solidification mainly consisted of calcium sulfate, calcium arsenate and calcium sulfite within optimum roasting parameters.IntroductionUtilization of refractory gold resources has been gradually concentrated on with the depletion of the gold resources which are easy to deal with in the world [1]. Sulfur and arsenic-bearing gold ore is a typical refractory gold one, in which ultrafme gold is encapsulated in the structure of metal sulfide minerals [2,3], so it gives poor recovery through direct cyanide leaching. These refractory ores need pretreatment before the process of cyanide leaching to undermine lattice structure of pyrite and arsenopyrite containing gold [4] so that the gold could touch with cyanide solution [5]. Among various methods of pretreatment, conventional roasting method is most effective, but this process generates gases such as S02 and As203 harmful to environment. Therefore solidification roasting was proposed to solve this problem occurring in the conventional roasting at the end of last century."

Jan 1, 2013

By V. V. Kutumbarao, M. T. Nimje, G. Balasubramanian

Wastes from the aluminium industry such as red mud from the alumina refinery, fly ash from the captive power plant and spent pot lining from the smelter, have been successfully converted into glass-ceramic products. The process involves addition of a small quantity of glass former along with traces of nucleating agents to aid crystallization, to a specific mixture ofred mud, fly ash and spent pot lining, followed by melting at around 1300°C and vitrification by cooling. The resultant glass is then converted into a glass- ceramic by a suitable heat treatment at around 700 - 750°C. The glass-ceramic products show excellent wear resistance, besides possessing an aesthetic appearance. The major application foreseen for such products is as decorative tiles in the building industry.

Jan 1, 2000

By H. Y. Sohn, M. Y. Mohassab-Ahmed

"As part of research to develop a novel flash ironmaking process using reduction of iron ore concentrate by natural gas or hydrogen, sulfur and phosphorus distribution ratios between MgOsaturated slag and iron were determined in the temperature range 1550-1650°C under three different gas atmospheres: H2/H2O, H2/H2O/CO/CO2, and CO/CO2. The distribution coefficients of sulfur (Ls) were 4.0, 2.0, and 0.8, respectively, under these atmospheres. The distribution coefficients of phosphorus (Lp) were, respectively, 8, 17, and 20 under these atmospheres. In the flash process over -25 wt% P and S volatilize during ore concentrate downward flight in the reactor shaft in addition to avoiding coke. Therefore, iron produced by the flash ironmaking process would have much lower sulfur contents than the typical hot metal produced by the BF.IntroductionGiven the issues related to large carbon dioxide emissions and energy consumption in the existing ironmaking technologies, a novel flash ironmaking technology was conceived by Sohn [1-3] at the University of Utah. This technology is the first ironmaking process that will convert iron ore concentrate directly to metallic iron in-flight. This process will produce iron directly from concentrate without requiring pelletization or sintering and avoid the need for coke. In addition, this process concept takes full advantage of the fine particle size of concentrate with a large surface area, which permits rapid reduction by a gas. In this novel ironmaking process, potential reductants and fuels are H2, natural gas, and coal gas. Therefore, an iron-slag bath is expected to be at equilibrium with gas atmospheres of mainly H2/H2O or CO/CO2/H2/H2O, respectively, corresponding to the use of H2 or natural gas/coal gas. Since the effects of an H2O- containing atmosphere on slag properties have not been studied before, it is critical for the development of the novel flash process to determine these effects. In H2-H2O-CO-CO2 gas mixtures under ironmaking conditions, H20 was found to have the most pronounced effect on the slag chemistry [ 4, 5]. In addition, it was found in this laboratory that water in the gas atmosphere affected the distribution of Mn between slag and molten iron [6]. Most previous work used CO/CO2 gas mixture to control oxygen partial pressure (p02) [7, 8]. Others used only inert atmospheres [9], although Kor and Richardson [10] used a mixture of C02/H2 to control p02. For phosphorus, previous research focused on Ar [11], Ar-CO mixture [12], CO [13], CO/CO2 [14] or N2/CO [15]. Therefore, it was necessary to investigate the effect of water vapor content in H2-H2O-CO-CO2 mixtures on the equilibrium distribution of sulfur and phosphorus between CaO-MgOsatSiO2-Al2O3-FeO- MnO (0.2-0.8 wt%)-P2O5 (0.1-0.9 wt%) slag and molten iron as part of the development of the novel flash ironmaking technology."

Jan 1, 2014

By John Anawati

Bauxite residue is an environmentally unfriendly byproduct of alumina manufacturing, produced worldwide in large quantities. This material contains 50– 100 ppm of scandium, a critical material for the production of stronger, weldable, corrosion resistant, and heat tolerant aluminum products. Aircraft manufacturers are particularly interested in Al–Sc alloys because of its ability to form weldable alloys that could potentially reduce aircraft weight by 15–20%. Because of its abundance and low cost, bauxite residue has the potential to be used as an efficient feedstock for valorization processes to recover its scandium content, while in turn degrading this problematic waste. In this project, we developed an efficient process to recover scandium and rare earth elements from a Canadian bauxite residue with high extraction yields, using industrially scalable and economical techniques. The process employs a modified version of sulfuric acid leaching and subsequent impurity removal by selective precipitation. This article outlines the current progress and design rationale in the development and optimization of this innovative and sustainable recovery process.

By Michael Meyer

In the past shredder fluff was discarded in landfills, but shrinking landfill space and the partly hazardous content of the fluff as well as its caloric value, all resulted in efforts to turn this waste problem into a an energy resource. In order to produce a fuel, the inorganic compounds have to be removed. Extensive analyses and particle size measurements were made on fluff from various shredder. For optimal separation all particles are reduced to a uniform, relatively small size. In a subsequent combined - screening and air classification - process, successful separation into organic and inorganic fractions is achieved. The inorganic fraction is treated in a heavy media or an eddy-current separator to recover the valuable metals, while the organic fraction is now suitable for thermal processing, such as fluidized bed gasification and using the resulting carbon as a chemical reagent.

Jan 1, 1995