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By Rauf Hurman Eric

The high temperature liquid miscibility gap in the Ag-Ag2S pseudobinary portion of the Ag-S system has been redetermined by very carefully conducted equilibration-quenching experiments. Samples were contained in evacuated and sealed silica capsules. The stratified liquid phase compositions were obtained by chemical analysis. The miscibility gap extends from 14 to 32.3 atomic percent at the monotectic temperature of 906°C and closes at around 1320°C.Thermodynamic properties of the liquid solutions, including the limiting activity coefficient of sulfur in molten silver were expressed analytically by using the sub-regular solution model which proved to be in excellent agreement with the experimental findings.

Jan 1, 2006

By Henrique Hesse, Rosana de Cassia de Souza Schneider, Wolmar Alípio Severo Filho, Ezequiel Bavaresco, Rodrigo Klamt, Luciano Roni Silva Lara, Luciano Dornelles

Alkyd resins are used in surface treatment. They are product of the glycerolysis followed by polymerization. In the present work it was studied methods of alkyd resin production from crude glycerol compared with resin produced with pure glycerol. This glycerol corresponds to 10% of the final products in the biodiesel production. The crude glycerol was partially purified with neutralization, flotation and adsorption. The experiments were accomplished with temperature control, inert atmosphere and with several quantities of the substrate. For the products characterization physic-chemistry methods, infrared spectroscopy and hydrogen nuclear magnetic resonance were used. According to the observed results, the resins obtained with crude glycerol have presented similar properties of the classic alkyd resin produced with pure glycerol. The exploitation of the crude glycerol reduces the stages and costs of the process.

Jan 1, 2008

By Han Ilhan

This paper discusses and describes aspects of a cost effective and safe tailings impoundment selection. In light of the current low metal prices and recent tailings embankment failures around the world, it is becoming extremely more important to develop tailings impoundment design that balance cost efficiency with safety. The paper will present critical design components associated with a tailings impoundment which need to be addressed during the planning phase. Procedures for identifying various tailings impoundment alternatives, and evaluation and selection of alternatives are presented.

Jan 1, 1999

By R. K. Amankwah

The ability of Streptomyces viridosporus in sorbing heavy metals from wastewater has been investigated. It was found out that the biomass of the soil microorganism could be used in sorbing Pb2+, Cu2+, Zn2+ and Ni2+ ions from acidic solutions of metal ion concentration between 10 and 100 ppm. Over 99% of Pb2+ and 88% of Cu2+ ions were sorbed from wastewater of concentration 10 ppm with Ni2+ and Zn2+ recording values below 50% for a contact period of 4 hours. The quantity of metal ions sorbed per gram of biomass from the wastewater was in the order Pb2+ > Cu2+ > Ni2+ > Zn2+ and this is related to their electronegativities. Biosorption was sensitive to variations in pH and in the range investigated; metal binding was optimum at 5.5. About 63% antimony was also sorbed from dilute cyanide solution.

Jan 1, 2003

By Andrew A. Fyfe

The start-up and operating results obtained at Zia Technology Inc.'s first commercial operating facility at Caldwell, Texas are described. The operation which stated in early 1991 is the first to employ the patented Inclined Rotary Reduction System (IRRS') with the associated 'all-metallic retort for the recovery of all metallics contained in EAF dust.

Jan 1, 1992

By Peter Kettle

This paper describes the performance of the copper industry over a period of some two decades and examines the theme that improvements in operating efficiency have not been matched by improved returns on capital. The financial performance of the copper industry is analysed using CRU's MICA database. Regression analysis indicates a two percentage point increase in operating margins but no increase in returns on capital. The gain in operating efficiency appears to have been mainly achieved in the mid 1980s. The investment boom of recent years has resulted in a rapid increase in the industry's level of debt and gearing ratio (now some 47%). Data on 44 copper mine projects is used to show the linear relationship between scale and capital costs. Typically new capacity costs some US$5,000 /tpy. The relationship between cash costs and capital intensity of projects is also plotted. The greater attention now being focused on efficient use of capital means that capital intensity rankings will become increasingly important in determining which projects go ahead.

Jan 1, 1999

By Jimsher N. Aneli

There are many experimental works on the investigation of temperature effect on the conductivity of polymers filled by carbon materials. However frequently the establishment of current nature in the polymer heterogeneous systems becomes difficult. This fact is explained by complexity of calculation of different physical or chemical phenomena passing in materials at variation of the temperature. Among these phenomena it must be noted some morphological changes in the structure of polymers. These changes reflex on the structure of conductive system of composites. So, it has been shown, that the character of temperature dependence of thermal noises level and conductivity of some polymers filled by carbon black essentially depend on some relaxation transition in the polymeric matrix. In this paper the effect of difference transitions in polymer matrix of filled by carbon black some polymers and rubbers have been investigated in a wide temperature range. The importance of such investigation is due to possibility of application of resistive temperature sensors based on conductive polymeric composites (CPC) to measuring technology. The experiments have been carried out in the cavity with regulation of temperature in the range 110-650K. The resistance of samples was measured by four electrodes method. The samples were obtained by hot pressing of dry mixture of powdered components at chosen temperatures, pressures and cooling time in the case of plastics and by peroxide vulcanization of the elastomers in the case of the rubbers. The samples were produced on the basis of the following thermoplastics: low density polyethylene, polytetrafluoroethylene, polycarbonate and polydimethylmethylvinilsiloxane.

Jan 1, 2006

By Katsunori Okaya, Gjergj Dodbiba, Hiroyuki Ono, Toyohisa Fujita, Seiji Matsuo

"In an attempt to raise the copper grade of Printed Circuit board (PCB) by removing other components, carbonization treatment was investigated. The crushed PCB without surface-mounted parts was carbonized under nitrogen atmosphere. After screening, the char was classified by size into oversized pieces, undersized pieces and powder. The copper foil and glass fiber pieces were liberated and collected in undersized fraction. The liberation of copper foil from the oversized pieces was also investigated. The copper foil was liberated easily from glass fiber by stamping treatment. Liberation rate of copper foil was high at high carbonized temperature. The experimental results indicated that 90% of oversized char was liberated and the copper foil recovery from PCB carbonized at 1073K was 110kg/t. The copper recovery from char powder by flotation was also investigated. 15% of the copper grade and 80 % of the copper recovery were obtained, whereas the removal rate of silicon was 55%.IntroductionWaste Electrical and Electronic Equipments (WEEEs) should be recycled because they have many kinds of valuable materials and most WEEEs include Printed Circuit Boards (PCBs). In Japan, about 30 km2 per year of Printed Circuit board (PCB) has been produced [1], PCBs are normally separated from WEEEs and picked up by hand and sold to non-ferrous metal market because PCBs include high grade of copper and other precious metal such as gold, silver and palladium [2]. However, PCB also has impurities such as silicon, aluminum and calcium which are slag materials in non-ferrous smelting process, and other harmful elements such as lead, bromine and antimony. Low grade PCBs are sold after removal of invaluable parts or sometimes land filled without any treatment"

Jan 1, 2011

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By Hong Yong Sohn

On the occasion of this symposium in my name, I reflect upon the contributions of my academic mentors and early associates who helped shape my professional career. I was fortunate to have these people around me during my graduate work and at the start of my professional career. In forming my view of the technical field and career, they represented academia, research institutions, industry, and different parts of the world.

Jan 1, 2006

By H. Kurama

In this paper, utilization of fly ash as a value added product in areas such as novel materials, waste management, fillers and agriculture is reviewed with the aim of helping the expand of the usage of fly ash and reduce the environmental and economic impacts of disposal. The used unburned carbon benefication/treatment methods such as low temperature combustion, froth flotation, partical size classification and electrostatic separations to remove unburned carbon particles from fly ash are also discussed.

Jan 1, 2006

By Larry G. Stolarczyk

The development of geosteering technology for geothermal reservoirs is challenged by the integration of electrically small antennas in small-diameter metallic drill rods. To be useful, the antenna pattern must achieve sufficient back-lobe suppression, preferably with a forward-looking pattern. Forward-looking capability requires an antenna array with phase control. The phase-controlled antenna pattern enables imaging of geologic structures ahead of and surrounding the well bore. This paper describes the development of electric and magnetic dipole arrays for small-diameter drilling pipe.

Jan 1, 2006

By Alexandr I. Volkhin

It is practically useful to separate copper from nickel at the fire refining stage of blister copper by transferring nickel in electrochemical inert silicides which are being concentrated further into the tank-house slimes. The treatment of copper melt by silicon-containing reagents is resulted in lowering the interfacial tension of the melt, its deoxidizing, selective siliconizing of in-melt nickel and forming a by-product with fluxing properties. Si-containing reagents have positive influence on results of fire and electrolytic refining, and further pulverizing of copper in plant conditions.

Jan 1, 2006

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By J. G. Peacey, P. Hancock, R. -Q. Li

A pyrometallurgical process for the direct recovery of zinc from zinc concentrates and zinc/iron residues has been proposed and tested extensively by Noranda. The process consists of smelting bone-dry zinc containing materials (sulfide concentrates and secondary zinc/iron materials) in a molten iron oxysulfide bath to volatilize metallic zinc into a SC^-free offgas. Sulfur contained in the feed materials is fixed as an iron oxysulfide matte for disposal. Thus, this process not only is capable of treating zinc sulfide concentrates and secondary zinc materials simultaneously, but also eliminates the need of sulfuric acid production. Detailed thermodynamic analysis and experimental test work are described in this paper.

Jan 1, 2000

By Adelana Adetunji

Ilmenite ore samples obtained from Dankoli in Zamfara, North Western Nigeria has been characterized using Energy Dispersive X-ray fluorescence (EDXRF) technique, X-ray diffraction (XRD) technique and the Neutron Activation Analysis (NAA) technique. The major constituents in the ore were quantitatively found to be TiO2 and Fe2O3 in concentrations of about 60wt% and 31wt% respectively. These occur in the forms of magnesian ilmenite (Fe, Mg)(Ti, Fe)O3, pure ilmenite (FeTiO3), and barium copper yttrium oxide (Ba2Cu3YO6.56) minerals. Other constituents/impurities in minor or trace quantities include MnO, Ta2O5, Nb2O5, Wo, SnO2, Hf, Zn, V, Zr, Co, Pb, Br, Al, Rb, Y, Th and U.

Jan 1, 2006

By Gustavo A. Munoz

Activated carbons owe their adsorption capacities to their extensively developed pore network structure. As a result, these adsorbents generally exhibit high specific surface areas. Currently, granular activated carbons produced from coconut shells are traditionally used for gold recovery by adsorption from cyanide leaching solutions. Magnetic activated carbons (MACs) for gold recovery from cyanide solutions produced from sources other than coconut shells have been developed at the University of Utah by mixing a magnetic precursor with a carbon source, and treating the mixture under controlled conditions of temperature and gas phase composition. The pore size distribution of the activated carbons is dependent on the degree of activation, among other factors. The significance of the MAC pore size distribution on gold adsorption kinetics and gold adsorption capacity is presented.

Jan 1, 2003

By V. K. Kalyani

The present paper discusses a three layer feed forward artificial neural network (ANN) model, trained using the error back propagation algorithm, has been established to simulate the column flotation circuit used for beneficiation of Sillimanite. Parameters such as superficial air velocity, wash water rate, froth height, % solid, feed velocity, sodium silicate and oleic cid are considered as process operating variables and % yield of Sillimanite is the output of the experiment. The results from the ANN modeling, involving the non linear relationship between inputs and outputs, indicate good agreement with experimental observations. The network model validates the experimentally observed trends. The optimal model parameters in terms of network weights have been estimated and can be used for computing parameters of the process over wide-ranging experimental conditions.

Jan 1, 2006

By Weyman Dunaway

This paper will present a description of the development and commissioning of the world?s most efficient process for manufacturing high purity aqueous zinc bromide. The method for making aqueous zinc bromide from metallic zinc and bromine comprises contacting zinc with bromine dissolved in a reaction solvent containing a metal halide salt. The reaction temperature is maintained at less than 60°C. The reaction solvent preferably comprises an alkali, alkaline earth, or transition metal halide; the halide salt preferably comprises a chloride or a bromide. One preferred method includes the step of recirculating the zinc bromide product stream back to the reaction vessel. The reaction vessel can be either a one stage or a multiple stage reactor. The resulting product stream is a high density aqueous zinc bromide solution. The process is so novel that Tetra Technologies, Inc. was awarded US Patent Number 6,036,937.

Jan 1, 2006

By G. St-Amant, V. Cloutier, E. Ghali, S. Jin, G. Houlachi

During the casting of lead-silver anodes, variations in cooling rates result in the formation of an uneven microstructure. The slowly cooled areas (SCA) have a coarser microstructure than that of the remaining part (called "the general zone"). The effect of anode microstructure on the electrochemical behavior was investigated using galvanostatic, potentiodynamic and electrochemical impedance techniques. The results show that the resistances for the two steps of the oxygen evolution reaction on the slowly cooled areas of Pb- Ag anodes are higher than that on the general zone. The double layer capacitance for the first step of the oxygen evolution reaction (OER) and the pseudocapacitance of the second step of OER on SCA are smaller than those on the general zone. The potentiodynamic results show that the amount of lead dioxide formed on the SCA is greater than that of the general zone of the anode. The potential decay curves after 30 minutes of galvanostatic polarization at 45 mA/cm2 show that the corrosion potential of the SCA is 200 mV lower than that of the general zone. This can lead to perforation because of the formation of a galvanic cell with a small anode and a large cathode.

Jan 1, 2000