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By Tabbetha A. Dobbins

We report studies concerning the time frame for catalytic reactions between NaAlH4 (sodium alanate) and TiCl3 during high energy milling. Spectral features in x-ray absorption spectra were analyzed for samples milled for various times (0 minutes, 1 minute, 5 minutes, 25 minutes, and 125 minutes). A structural transition from Ti3+ to Ti0 is observed within the first 5 minutes of milling. The Ti0 structure persists for samples milled for times longer than 5 minutes?even after those samples underwent a subsequent single hydrogen desorption/absorption cycle. Samples milled for less than 5 minutes retain Ti3+. For samples milled for 1 minute, the Ti-K edge position shifts from Ti3+ to Ti0 after a single desorption/absorption cycle. However, the first coordination sphere around the Ti0 absorber occurs at longer distances for 1 minute milled sample. These results hint at the formation of Ti0 pure metallic clusters upon desorption/adsorption cycling of 1 minute milled sample. Previously reported x-ray absorption spectroscopy studies have demonstrated the structural transition from Ti3+ (in TiCl3) to Ti0(determined to be TiAl3 found at the surface of the alanate powder). Aluminum deficiency on the NaAlH4 lattice is responsible for controlling hydrogen absorption capacity. These time-resolved spectroscopy studies suggest the possibility for controlling aluminum deficiency, while still maintaining titanium activation of the alanate powder, by manipulating the coordination environment of the titanium dopant during the first five minutes of high energy milling. Specifically, a possible approach to mitigating aluminum deficiency during doping would be to introduce an alternative species to which the to Ti3+ catalyst would form a metallic bond after the TiCl3 has attached at the surface of the sodium alanate powder and before the Ti3+ forms the TiAl3 intermetallic species.

Jan 1, 2006

By Katsutoshi Inoue, Shafiq Alam

Several novel types of chemically modified chitosan were prepared by immobilizing functional groups of EDTA and DTPA onto polymer matrices of chitosan in order to investigate their potential for mutual adsorptive separation among rare earths. Following the batch wise adsorption tests to elucidate their basic adsorption characteristics for rare earths, mutual separation was carried out using a column packed with the chemically modified chitosan. The separation between Sm(III) and Y(III) was tested using a column packed with EDTA-type chitosan while mutual separation among 4 light rare earths, La(III), Ce(III), Pr(III) and Nd(III) was tested using a column packed with DTPA-type chitosan. In both cases, satisfactory mutual separation was achieved by the chromatographic operation using these chemically modified chitosan.

Jan 1, 2014

By Monteirom Sergio N., Romulo L. Loiola, Giulio R. Altoe, Noan Simonassi, Frederico M. Margem

"The environmental concern is creating pressure for the substitution of high energy consumption materials for natural and sustainable ones. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as flexibility and toughness. So there is a growing worldwide interest in the use of these fibers. Buriti fiber extracted from buriti palm tree (Mauritia flexuosa), presents some significant characteristic, but until now only few studies on buriti fiber were performed. This work aims to make the analysis of the tensile strength of epoxy composites reinforced with buriti fibers. This analysis was performed in fibers with diameters between 0.1 and 0.4 mm. Those fibers were incorporated into the epoxy matrix with volume fraction from 0 to 30%. The fiber diameters were measured by a profile projector. After fracture the specimens were analyzed by a SEM (scanning electron microscope).IntroductionNatural fibers with high amount of cellulose, also known as lignocellulosic fibers, have been used from primeval times of our civilization. In the last century, synthetic fibers such as nylon, carbon, aramid and glass fibers gained interest owing to superior strength and precise dimensional control. Natural fibers were then replaced by synthetics in many fields such as textiles, sports goods and appliances. In the past decades, however, environmental issues drawn, once again, the attention to lignocellulosic fibers as possible substitute for intensive energy-consuming and long term polluting synthetics, specially the glass fiber(1). In particular, research works have disclosed the potential advantages associated with the use of lignocellulosic fibers as the reinforcing phase in polymer composites(2-3). Among the advantages it is worth mentioning the renewability, recyclability, biodegradability and the fact that natural fibers are neutral with respect to CO2 emissions responsible for global warming. In addition to environmental benefits(l,10) the lignocellulosic fibers present economical advantages, such as worldwide abundance and comparatively low costs as well as some technical properties associated with flexibility and toughness( 4), which contribute to the performance of automobile components fabricated with natural fibers composites(l 1-13)."

Jan 1, 2013

By Guanyong Shi, Zhihe Dou, Cong Wang, Ting'an Zhang, Hongyan Zhang

We prepared the CuCr alloy by thermit reduction-electromagnetic casting. But there are the defects such as stomata and oxide inclusions in CuCr alloy. In this paper, the existing state and distribution of inclusions and stomata in CuCr alloy are systematically analyzed. The alloy was characterized via SEM, EDS and metallographic microscope, in which the existing state and micro-structural defects of inclusions are analyzed. The results show that: there are three distinct areas: copper-rich areas, chromium-rich areas and the inclusion areas. Inclusions are mainly in the form of stomata and Al2O3 phase, mainly locating in the copper-rich phase and the interface area of chromium-rich phase and the copper-rich phase. Then, the composition of phases of the smelting slags and alloy were characterized via XRD. The results show that: the slag consists of Al2O3 and a little of Cr, the alloy consists of Cr, Cu and a little of Al2O3.

Jan 1, 2015

By W. G. Davenport

This chapter extends our mathematical description of flash smelting to -nitrogen in the flash furnace blast. As in chapters 4 and 5, the discussion is limited to auto thermal smelting (no hydrocarbon combustion). Hydrocarbon combustion is introduced in Chapter 9. Outokumpu flash furnace blast is a mixture of air and industrial oxygen. Most of its N2 originates in the air portion of the blast. A small portion originates as an impurity in the industrial oxygen. The nitrogen entering a flash furnace must always be heated from its input temperature, 298 K in this chapter, to its off gas temperature, -1500 K. Energy must be supplied for this purpose. With auto thermal smelting, the energy is-provided by oxidizing extra Fe-and S.

Jan 1, 2001

By Richard D. Hagni

Ore microscopy is a useful technique to detect and study the ore minerals that are associated with sediment-hosted and volcanic-hosted deposits of finely disseminated gold and silver. Ore microscopy can be used to determine the: 1) precious metal-bearing minerals in some ores, 2) associated ore minerals that may form geochemical exploration halos, 3) character of iron sulfide grains, 4) extent of sulfide oxidation, 5) character of oxidized iron minerals, 6) character of original sulfide grains from a study of the hypogene and supergene oxidized ores, 7) relative time of oxidation, 8) character of organic matter, 9) minerals that may consume excessive amounts of cyanide solution, 10) extent of silicification and silica encapsulation, and 11) possibility of salting.

Jan 1, 1987

By H. Y. Sohn, Y. Mohassab, D. Q. Fan, M. Elzohiery

A flash ironmaking process is being developed at the University of Utah in which iron is produced directly from magnetite concentrate. The kinetics of magnetite reduction by a mixture of H and CO gases was determined in the 2 temperature range 1150–1600 °C. Over 90% reduction degree was achieved at a temperature as low as 1250 °C within 4–6 s which is the typical residence time available in a flash reactor. The kinetics results were applied to experimental data obtained in a laboratory flash reactor in which H and CO gas mixtures were 2 produced from in situ partial oxidation of natural gas with oxygen. CFD was used to simulate the laboratory reactor,and the results were in good agreement with the experimental data.

Mar 1, 2017

By Bingyi Bai, Wangjun Peng, Yanling Guo, Jieyu Zhang, Guoding Gao

The phase transformation of bayan obo ore with high concentration of iron and calcium was reduced at temperatures no more than 1000℃ were investigated in this study. The samples with insufficient carbon were treated at the temperature using a vertical furnace with a thermogravimetry (TG). The mineral phases and content were examined using Xray diffraction (XRD) and X-ray fluorescence spectroscopy (XRF) respectively. The complex phases of bayan obo ore transformed to some simple phases after treated with different content of carbon at the same temperature for 10 hours. The result of XRD、 XRF and TG showed that the reduction degree of Fe3O4 phase formation varied with the temperature and the carbon content of bayan obo ore.

Jan 1, 2015

By Wenjun Duan, Zhimei Wang, Tianwei Wu, Qingbo Yu

In order to recover the waste heat of molten blast furnace slag, a reactor with top-submerged lance was established. The numerical simulation and experiment study of the flow characteristic in the reactor were conducted. The mathematical model of reactor was established and the Euler-Euler model was employed to simulate the gas-liquid flow in molten slag bath. Meanwhile, the experiment results were obtained and compared with the simulation to testify the accuracy of the established model. According to the bubble behavior in bath, there were four stages: initial expansion stage, bubble detachment stage, freedom lift up stage and bubble broken stage. When the flow field in bath fully developed, the gas fraction decreased with the increasing of bath depth. During injection process, the area near the nozzle and lower the bath would first generate two symmetric heliciform flow regime, and then the flow regime in whole bath would become irregular because of bubble lifting up and rupturing. The gas fraction in bath, the average velocity and turbulence energy of slag would decrease before it increased to maximum and then it would keep fluctuate in a range.

Mar 1, 2018

By Liu Wei-feng

In this paper, the practice of separating precious metals from base metals in gold-antimony alloy by selective chlorination leaching under controlling potential in China has been introduced in detail. The precious metals and the base metals can be separated completely when the complex gold-antimony alloy is treated by this process. The impurity metals were removed effectively since the leaching efficiencies of copper, nickel and antimony are over 99%, with direct recovery of gold being 99.83% that is about 20% higher than that of the original process and silver, antimony, copper and nickel are also recovered effectively. The gold grade of the resulting crude gold powder can reach to 94%.The new process has been applied in the treatment of gold-antimony alloy for two years, and many former procedures have been cancelled, such as electrolysis, Anode slime leaching by nitric acid, smelting in crucible and blowing in muffle. The new process is more shorten, lower cost and friendly to the circumstance comparing to the original process.

Jan 1, 2008

By Marietta Canty

A paper is presented in which an innovative biological process is described for the treatment of cyanide-, metals-, and nitrate-contaminated mine process water. The technology was tested for its ability to detoxify cyanide and nitrate and immobilize metals in wastewater from agitation cyanide leaching. A pilot-scale demonstration is described in which a pilot plant was constructed to demonstrate the technology on a mine process waste stream at a mine in Nevada. The demonstration was performed Jointly under the Mine Waste Technology Program (MWTP), which is funded by the U.S. Environmental Protection Agency (EPA) and is jointly administered by the U.S. Department of Energy's (DOE) Western Environmental Technology Office (WETO) and the Superfund Innovative Technology Evaluation (SITE) Demonstration Program under Interagency Agreement Number DW89938513-0 I-0. MSE Technology Applications, Inc. (MSE) located in Butte. Montana, was the contractor responsible for conducting the project, and Pintail Systems, Inc., of Aurora. Colorado, was the technology provider. The pilot-scale unit was field-tested at the Echo Bay McCoy/Cove Mine southwest of Battle Mountain, Nevada. The biotreatment process was considered to be successful in destroying cyanide in the mine process water. The process was also determined to be effective in removing metals. The pH was consistently neutralized, and nitrates were successfully removed from the mine process water. As a result of conducting these pilot-scale tests, the biotreatment process was concluded to be an innovative, cost-effective alternative for the treatment of mining wastewaters.

Jan 1, 1998

By Yong Hwan, Wang Jian-Jun, Cai Jiu-Ju, Chen Chun-Xia

"The quantity of residual-heat and its recovery in some Chinese sinter plants are investigated. The main factors affecting energy consumption are analyzed using exergy analysis combining energy level analysis. It is indicated that the “gradation recovery and cascade utilize” of discharged gas and sinter residual heat in different temperature is the direction and the available approach to reduce energy consumption of the sinter process. Taking an iron& steel enterprise as an example, the three-ranked scheme of residual-heat recovery is put forward: ?Part of the sinter gas is used for warm-up and dryness; ?The high-temperature part of the cooler and exhaust-heat boiler are actualized as a closed-circuit, which can produce high-quality steam to generate electricity. ?The waste air in low-temperature part is introduced to sintering machine to support combustion. According to the CDQ which can recover the coal heat, the assumption of pot-recovery is put forward to replace the belt cooler. The two equipments of residual-heat recovery are analyzed in the aspect of energy consumption and CO2 reduction.1. IntroductionEnergy consumption in sintering is only inferior to iron-making in iron& steel enterprises, accounting for 10%~20% of the total energy consumption. A lot of residual heat is produced during sintering, and mostly from the sinter ore and waste gas. Sensible heat of hot sinter ore and discharged gas have accounted for 60%[1] (equals to 40 kgce/t-ore), which are the key point of sintering waste heat recovery. Discharge gas of sintering is mostly composed of flue gas deriving from sinter bed’s combustion, and the content distribution of H2O and O2 and the temperature of the gas along the length of belt-type sintering are shown in Figure1[2,3]. Currently, the sensible heat of hot sinter ore is mainly recovered by circular cooler and cooled by blasting air: the temperature of cooled discharge gas brings down from 350? to about 100? along with the decrease of sinter ore temperature. It is significant to recovery and reuse the waste heat as 4000~6000m3 discharge gas per ton of ore can be produced"

Jan 1, 2008

By R. T. Hernández, I. Hilerio, A. Altamirano, M. A. Barrón

"The principal objective for finishing surfaces is to protect and/or to decorate them. This can be achieved by adding or removing material from the work surface. The addition of aggregated material is called coating or recovering. In this work, mecano-chemical techniques are investigated for surface finishing. For these techniques, barreling or polishing by the friction method will be used. These are the cleaning or finishing processes most used for great volumes of small pieces. These methods improve the surface finishing by eliminating burrs, sharp pointed, tool marks and crusts of casting. They are used to clean metallic pieces, ceramics and polymeric materials. The process is based on rubbing or friction by abrasives. The pieces are arranged in the barrel with an abrasive and an additive (water or chemical additive). The machine produces a rotating movement on the pieces. When the abrasive passes against the surfaces of the pieces, it produces an action of rubbing and impact that cleans the surfaces. The rubbing action is developed when the upper layer of the charge slides to the lower extreme when the barrel rotates. The barrel can be hexagonal or octagonal to facilitate the sliding of the charge. The barrels can be between 15 to 120 cm in length and they can have almost any diameter and velocity of rotation. There are several types of barrel: individual, multiples, and multiple compartments. The barrels are rotated using a wheel spindle or rolling pins, that the can ride horizontally or be tilted to produce an additional movement of the charge.IntroductionShot penning is a cold method in which compressive effects are induced on an exposed surface of a metallic piece, by the impact of a rain of shots directly on the surface of the metal, at great speed under controlled conditions. This differs from cleaning with the help of air, because even when shot penning cleans the surface of the metal, this function is incidental. The main purpose of shot penning is to increase the resistance of the piece to fatigue. The process has other applications: raises the tensile strength and decrease corrosion fracture."

Jan 1, 2012

By R. Ghisleni, R. E. G. Bohrer, L. Radtke, R. M. C. Santana

"The major source of environmental pollution in urban areas is the transport sector and its impact on human health and the greenhouse is preoccupying. In many works of literature is monitored the pollutants in urban cities, however in specific areas such as universities, they are scarce. Therefore, the aim of this work is to monitorate the gaseous pollutans in a bus terminal at Santa Cruz do Sul University-UNISC and to develop a control framework of the air quality. Six points were selected for monitoring, being one of them inside a bus. The monitoring of CO, HC and CO2 were carried out on arrival and departure of the bus. Preliminary results conducted in a day of spring showed that the most critical condition was during the night shift, where the concentration of CO (200 ppm) was the highest, caused by the vehicles increase, due to the larger number of students.IntroductionThe first major global assessment of climate change science in six years has concluded that changes in the atmosphere, the oceans and glaciers and ice caps show unequivocally that the world is warming. The report released on February 2, 2007, the first of four volumes to be released this year by the IPCC, also confirms that the marked increase in atmospheric concentrations of greenhouse gases is the result of human activities.The transport sector has become by far major source of environmental pollution in urban areas. The continual traffic growth has raised concerns over the impact of traffic emissions on human health and urban environmental quality, and has fuelled the demand for a coherent regulatory framework for the management of traffic, air quality and emission at urban level, as well as at regional and national scales.In Greater Metropolitan São Paulo, Brazil, fossil fuel combustion in the transportation system is a major cause of outdoor air pollution (Miraglia&El Kouri, 2007). In China several studies on gaseous emissions are being conducted by F. Costabile&Alegrini, (2007), developed a study on the pollutants in the city of Beijing suggesting methods for the control of pollution.The results obtained from the estimation of the atmospheric pollutants emitted monthly in Campo Grande/MS, Brazil, by buses and minibuses, which employ diesel, biodiesel or natural gas as fuels showed that the substitution of diesel by biodiesel would diminish the emissions of pollutants (Kozerski&Hess, 2006)."

Jan 1, 2008

By Jin-Chun Kim

Nanosized W based powders (W, WC, WC-Co) were produced by chemical vapor condensation (CVC) process. Two different solid W(CO)6 and Co2(CO)8 metal-organic materials were used as precursors. CVC experiment was conducted in the temperature range of 400-1100. As-CVC WC1-x powder which had non-stoichiometric composition was carburized by using of the CH4-H2 mixed gas in temperature range of 750-850. The CVC W and WC1-x powders showed loosely agglomeration structure, and the Co powder had intricate long stand structure because of intrinsic magnetic properties of Co phase. Carbon content of the CVC powders controlled by gas-phase carburization was well matched with theoretical WC stoichiometry (6.13wt%).

Jan 1, 2006

By J. E. Wey

Extraction of cobalt from cobalt sulfide and cobaltite flotation concentrate from the Blackbird Mine, Idaho, was investigated using an adapted strain of Thiobacillus ferrooxidans. Cobalt extractions as high as 100% were realized in the inoculated experiments, whereas only 4% extraction was obtained in the sterile run. The influence of pulp density on the rate and extent of cobalt extraction was also determined. It was found that the extraction of cobalt followed predominantly the indirect mode of bacterial activity. In this process, ferric iron oxidizes cobaltite to cobalt sulfate and ferric arsenate while being reduced to its ferrous state; the bacteria continuously re-oxidize ferrous to ferric iron. Electrochemical measurements using cyclic voltammetry suggested that cobaltite oxidation involved a number of intermediate reactions.

Jan 1, 1993

By Y. H. Liu

Several foaming aluminum samples of different density were prepared in a semi?industrial scale experimental system, Their properties such as the energy absorption characteristics, mechanical properties, heat conductivity and acoustical properties were measured. The results showed that the foaming aluminum with a density of 0.5 to 0.6 g/em3J has the best energy absorption and this makes it suitable as the ensuring bar of the automobiles and also as a cushion material for the engine. The foaming aluminum with a density of 0.25 to 0.4 g/em3 has the best acoustical properties and heat conductivity resistance, which is suitable for the door filling material, the ceiling and the partition or the car engine.

Jan 1, 2003

By C. Allen, A. Roy, J. W. Evans

A spouted bed electrode (SBE) has been used, in laboratory experiments, to electrowin zinc from zinc chloride electrolytes with the objective of determining the suitability of this electrode for commercial application. Zinc was successfully electrowon at current densities ranging up to 4,38 lA/m2, which are an order of magnitude larger than those used at present in the zinc industry. Current efficiencies, for the cell with the SBE, have been as high as 90% and DC energy consumption as low as 2.8 kWh/kg zinc deposited. The performance of the cell has been measured as a function of current density, anode type, cell diaphragm, addition of tributyl ammonium chloride and purging of the electrolyte (to remove dissolved chlorine).

Jan 1, 2000

By Yuanbo Zhang, Yingming Chen, Zijian Su, Bingbing Liu, Jun Chen

Iron, tin-bearing tailings is a kind of hazardous solid waste generated from cassiterite dressing operation. It is difficult to utilize the tailings by present mineral processing methods due to the complex dissemination characteristics. In this study, a process of gas-based magnetizing roasting followed by magnetic separation was studied for separating and recovering iron from the tailings. The effects of roasting and magnetic separation parameters on the recovery of iron were systematically investigated. The optimum parameters were proposed as follows: CO/(CO+CO2) content of 5%, roasting temperature of 850 C, roasting time of 60 min, grinding particle size of 90% less than 45 μm and magnetic field intensity of 800 Gs. Under these conditions, the magnetic concentrate containing 68.5% Fe and 0.06% Sn was achieved, which can be used as high-quality raw materials for direct reduction iron production.

Jan 1, 2016

By Jaeheon Lee

Gold-copper alloys are shown to form during the cementation of gold on copper in a solution containing 0.25M [S2O32-] at 25oC. The alloy composition is strongly dependent on the initial Cu:Au ratio in solution and ranges from Au3Cu to AuCu3. XPS results for Au, Cu, S, and O are reported as a function of depth through an entire deposited film with an initial solution containing 20 ppm [Au] and 30 ppm [Cu]. The deposit contained about 20 atomic % gold and was predominantly Cu3Au. Underpotential deposition (UPD) theory is discussed as a mechanism for explaining the formation of these alloys. Several other systems that produce alloys during contact reduction/cementation are also discussed.

Jan 1, 2003