Search Documents

By Sayavur Bakhtiyarov

Keywords: Rheology, Viscoelastic, Oil In this paper we present the results of the rheological property measurements on viscoelastic composite materials used in oil industry. Laboratory experiments were carried out to determine important thermophysical, rheological and mechanical properties of the test materials using both the standard commercial and in-house made equipment. The composites with the paramagnetic particles (?-iron oxide) are exhibited a significant magnetic memory after magnetic treatment. The measured value of the yield stress after the magnetic treatment increased almost twice in comparison with the yield stress value of the magnetically untreated composite. The yield stress of the composite material exponentially decreases with time and reaches its magnetically untreated value after 15 hours. The yield stress also increases with the amount of the paramagnetic powder additive, and it reaches a maximum value at 8 wt-% of this additive. The obtained results provide valuable information for computer modeling of the viscoelastic fluid flow in pipes of complex geometry.

Jan 1, 2005

By Jukka Tuominen

The history of making blister copper in an Outokumpu Flash Smelting Furnace dates back to the late 1960?s, when Outokumpu first piloted the Outokumpu Direct Blister (ODB) process. The first commercial scale applications have been in use at Glogow, Poland, since 1978 and at Olympic Dam, Australia, since 1988. These applications utilize special concentrates, which are low in iron, and thus the formation of slag is also low. In 1995 the same principle was applied to smelting copper matte into blister copper in industrial scale at Kennecott Utah Copper. This application, the Kennecott-Outokumpu Flash Converting process, will celebrate its 10th anniversary of commercial scale operation this year. This paper outlines the development in efficiency and flexibility of Blister Flash Smelting processes compared to other smelting and converting options. The focus is on the economical aspects i.e. on the total feasibility of both greenfield investment projects and revamping of existing smelters.

Jan 1, 2005

By Ramana G. Reddy

Thermodynamic modeling and experimental study on impurity capacities and their distribution between mattes or metal and slags in smelting, converting and refining of non-ferrous metals was discussed. A brief review on the recent developments in copper smelting and converting is presented. The analysis showed that, copper smelting capacity increased by a factor of 10 since 60's, smelting rate increased by a factor of more than 5 and process fuel equivalent decreased by a factor of 2. A thermodynamic model for prediction of impurities capacities in slags and their distribution in mattes and slags was developed. The impurities capacities (i.e. sulfur and arsenic) of slags were calculated a priori with no adjustable parameters using the Reddy-Blander model. The capacities predictions were made in a wide range of matte and slag compositions, Pso, and temperatures in conditions pertaining to copper and lead industrial slags. The calculated results for sulfide and arsenate capacities are in good agreement with the available experimental and industrial copper and lead industrial slags data. The sulfide and arsenate capacities in copper slags (fayalite, ferrite and olivine) and lead slags are reviewed. The application of RB model predicted ratios of 02 and S2 partial pressures in industrial copper smelting processes are discussed. Application of this model for the prediction of Sb, Bi and other impurity capacities and their distribution ratios in mattes or metal and slags, in industrial smelting and refining processes is discussed.

Jan 1, 2003

By K. Morsi, S. K. Kassegne, A. El-Desouky, K. S. Moon

"Current Activated Tip-based Sintering (CATS) is a new process for the powder-based fabrication of macro, micro and possibly nano-scale features and shapes. This new and unique process enables selective sintering of powders by localizing electrically activated sintering conditions through a stationary or moving electrically conducting tip. We present preliminary experimental results on the effect of tip size in the CA TS process as well as the effect of initial powder particle size on the sintering behavior of nickel powder.IntroductionSpark Plasma Sintering (SPS) has been the center of attention of numerous researchers due its noticeable advantages over conventional sintering techniques such as rapid heating rates, lower sintering temperature and shorter holding times. Research on SPS has been applied on a wide variety of materials such as pure metals [ 1], ceramics [2], composites [3], nano-materials [ 4], biomaterials [ 5], shape memory alloys [ 6] and many other material systems. However, it has been mostly limited to bulk materials with simple shapes with a few exceptions ofresearch efforts where the effect of electric current was combined with metal forming processes such as spark plasma extrusion [7,8] and electric rolling of powders[9]. In this paper a novel process (Current-Activated Tip-Based Sintering (CATS)) is discussed where electric current and pressure are applied simultaneously through a small conducting tip (stationary or moving) over a conducting powder compact. This process has the potential advantages of sintering complex geometries with minimum energy requirements as unconventionally high current densities can be achieved due to the small contact area between the tip and the powder compact. Furthermore, by controlling the tip size, it can be possible to sinter features on the macro-, micro- and even nanoscales."

Jan 1, 2011

By Saynbaatar, Gangping Ma, Jianhua Fu, Qiqige, Jinghua Wang

The influence on the performance of foam concrete made by replacing cement with some industrial waste residues was researched in this paper. The result shows that the 7d and 28d compressive strength of foam concrete increases firstly and then decreases with the increasing amount of industrial waste residue. The proper added range is 10%-20% for steel slag, blast furnace slag and coal ash, but, 8% for desulfurized fly ash. With the proper adding ratio, the compressive strength of foam concrete always increased comparing with the pure cement foam concrete. When adding 48% of the compound industrial waste residues, the 28d compressive strength of the foam concrete reached the 2.9MPa which could match the pure cement foam concrete. The results indicates that there is a synergistic effect among the compound industrial waste residue, and this effect is benefit to improving the compressive strength of foam concrete.

Jan 1, 2015

By Junji Shibata

Keywords: Synergistic effect, Solvent extraction, Nickel ion, extractant mixture Waste solution from the Ni non-electric plating process contains 4.0 kg/m3 Ni (II), 0.1 kg/m3 Fe (III), 0.01 kg/m3 Zn (II), 48 kg/m3 SO42-, 98 kg/m3 HPO32- and 31 kg/m3 lactic acid as a typical composition. Solvent extraction, cementation, ion exchange resin and precipitation methods may be used for the treatment of this kind of solution. In this study, solvent extraction of Ni (II) is investigated by using two kinds of extractants in order to clarify the relationship between extraction equilibrium (static synergistic effect) and extraction rate (dynamic synergistic effect) for several extractant mixtures. The static synergistic effect does not take place significantly for the extractant mixtures of acidic extractants and neutral organphosphorous compounds, while a large static synergistic effect is confirmed when the extractant mixtures of acidic extractants and nitrogen-containing compounds are used. Nickel ions can be extracted in the wide pH range of 3.0-8.0 without any pH adjustment by using the several extractant mixtures. At the same time, the extraction rate remarkably increases by using the extractant mixtures of acidic extractants and nitrogen-containing compounds.

Jan 1, 2005

By Kafui Nyavor

The indirect, and the direct contact mechanisms of bacteria oxidation of sulfides were studied using Thiobacillus ferrooxidans and pyrite. The aim was to determine which of the two generally aeeepted mechanisms played a dominant role, if any, during acid mine drainage (AMD) formation from the oxidation of sulfide minerals. The results show that at a pH of 4.5 where T. ferrooxidans are quite active, but where initial chemical oxidation of pyrite to Fe2+ is limited, the bacteria were unable to directly oxidize pyrite to any significant extent. Whereas, in the presence of Fe2+, T. ferrooxidallS assisted oxidation of pyrite by the indirect mechanism was observed and sustained over the pH and Eb range where the bacteria is active. The results lead to the conclusion that the direct contactmechanism of pyrite oxidition by T. ferrooxidans is insignificant. The predominant, and possibly the only, pathway involves the indirect bacteria oxidation of available Fe2+ to Fe3+, which in turn oxidizes FeS2 to generate additional Fe2+ and acidity in a cyclic process.

Jan 1, 1996

By Jin Qiu

Experiments were performed to determine the extent of minor element elimination that occurred when mixtures of copper smelter dust and copper concentrate, were calcined under vacuum. Almost complete removal of the As, Sb, Bi and Pb occurred due to the conversion of the minor element compounds of these elements into their highly volatile sulphides by reaction with sulphur from the concentrate. Heat and mass balance calculations of the slag-blow in a copper converter found that ~30 tonnes of the vacuum calcine could be used to produce 100 tonnes of copper as white metal. The use of dirty concentrate as the sulphidizing agent in the vacuum calcination means that the minor element treatment capacity of the smelter complex could be increased by 60 %. Also the productivity of the converters may be increased by up to 8 % due to the supply of copper values and oxygen in the calcined mixture.

Jan 1, 2005

By Anish Kumar

Keywords: Ultrasonic velocity, Poisson?s ratio, Elastic constants A new correlation has been established between two independent elastic properties, ultrasonic shear wave velocity and Poisson?s ratio, in a wide variety of isotropic solid materials, such as pure metals, ceramics, polymers and intermetallics. It has been shown for the first time that Poisson?s ratio decreases with increase in elastic moduli, E & G and ultrasonic velocities. This new correlation between two independent elastic constants may lead to the reduction in independent elastic constants for isotropic solid materials from two to one, at least for a given alloy system with different microstructural conditions.

Jan 1, 2005

By Zhiqiang Han, Anil K. Sachdev, Baicheng Liu, Guomin Han, Alan A. Luo

The growth of precipitate phase ,B-Mg11Al12 in Mg-Al alloy is closely related to interface anisotropy and elastic interaction. The aim of this work is to investigate the effects of the interface anisotropy and elastic interaction on the morphology evolution and growth kinetics of the precipitate. In the work, the precipitation of ,B was studied using phase field modeling. In the model, the chemical free energy of the precipitate and the matrix were obtained via thermodynamic calculation. It is demonstrated that the interface anisotropy results in lath-shaped precipitate and the elastic interaction affects the shape of the end of the precipitate. The interface anisotropy causes uneven growth in different directions and the elastic interaction influences its preferential growth orientation. By combining the interface anisotropy and elastic interaction in the phase field modeling, the results showed that the precipitate phase has a lath-shape with lozenge ends, which is in agreement with experimental observations.

Jan 1, 2013

By Mark Jolly, Xiaojun Dai

"Foundry engineers in the traditional foundry usually regard the quality of casting component as the most important issue and leave the energy saving or energy efficiency as the subsidiary one. This frequently causes disproportionate energy consumption as a result of the inefficient casting processes used and increases the production costs. This paper presents the novel CRIMSON aluminium casting process and compares its facility and melting process with traditional melt furnaces and aluminium alloy melting process. A real example is investigated to demonstrate quantitatively how the traditional foundry wastes energy and what the improvement of energy efficiency can be achieved using the new CRIMSON method. The results of this investigation will help the foundry engineer recognize the importance of energy saving and demonstrate how to use this new technology to reduce production costs and carbon footprint without decreasing the quality of the cast component.IntroductionAluminium melting in metal casting industry is an energy intensive process where it is estimated that the energy consumption is in the order of 1,700 ~ 4,700 kWh tonne-1 in using crucible and natural gas [1]. Different countries may use different energy resources for aluminium melting: in US the main energy resources are natural gas, electricity and coke [2] and in UK most of the foundry use electricity, gas and oil as energy resources [3]. Due to the pressure of rising energy price and the strict environment law, it is anticipated that under the right socioeconomic conditions, the efficiency optimisation of industrial process can be an important step toward increased industrial sustainability [4]. In metal casting industry the energy efficiency of a casting facility depends largely on the efficiency of its melting and heat treating performance. In association with the two performances, over 60 % of the total process energy costs are represented in a typical casting facility [5] where there are huge opportunities for metal casting industry to adopt the best energy practices for potential energy saving. How to ameliorate the current processes for increasing energy efficiency will have a vital effect on reducing the production costs and increasing the competitiveness. For instance, by implementing some state of the art technologies such as the CRIMSON method in aluminium alloy casting will make use of such opportunities."

Jan 1, 2011

By Duclerc Fernandes Parra, Vijaya Kumar Rangari, Washington Luiz Oliani, Ademar Benevolo Lugao, Nilton Lincopan

Due to its versatility and low cost, polypropylene (PP) is one of the most widely used polymers in the world, consequently in research and development of new products. The polypropylene modified was prepared by gamma irradiation in acetylene at 12.5 kGy dose, technical polymer also known as high-melt-strength-polypropylene (HMSPP). It was mixed with montmorillonite (MMT) clay and silver nanoparticles (AgNPs) for bactericide activity. HMS-Polypropylene-clay-silver nanocomposites were manufactured using twin-screw extruders. Those materials were prepared by a melt mixing process via twin screw extrusion with a wide range of processing conditions. The polypropylene nanocomposites (PPNC) surfaces were exposed to gamma-radiation (60Co) source in presence of nitrogen as inert atmosphere at 1; 3; 5; 10; 20 and 50 kGy doses for modified the surfaces in order to enhance biocide activity. The samples surfaces were characterized by Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and evaluated by determination of bactericide effects. The results indicate the formation of structures predominantly intercalated of HMSPP nanocomposite. Contact tests for antibacterial activity of the hybrid polymer were applied against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. The irradiations on the samples surfaces were insufficient to promote activity on contact biocide tests.

Mar 1, 2018

By T. Sakaguehi

Some attempts were made to recover and remove of uranium that may be present in refining effluents, mine waste Water, and other waste sources by using microbial biomass. To establish which microorganisms accumulate the most uranium, 135 species of microorganisms (42 bacteria, 26 yeasts, 34 fungi and 33 actinomycetes) were screened. Of these 135 species of microorganisms tested, extremely high uranium absorbing ability was found in Pseudomonas stuzeri, Neurospora sitophila, Streptomyces albus and Streptomvces viridochromogenes. In addition to the research on uranium uptake, thorium recovery by using microorganisms was investigated. High abilities were found in Streptomyces levoris and Bacillus subtilis. The selective accumulation of heavy metal ions by various microorganisms has also been examined. Uranyl, mercury and lead ions were readily accumulated by almost all of the species of microorganisms tested. Actinomycetes and fungi differ from many bacteria and most yeasts in their selective accumulation of uranium, and mercury. The basic features of uranium uptake by Streptomyces viridochromogenes, a microorganisms with high uranium-uptake ability, were investigated systematically. Synthesizing these results, we suggested that the accumulation of uranium into these microbial cells is not directly mediated by any metabolic process:, but almost completely dependent upon physicochemical adsorption on the cell components. In addition to this fundamental research, uranium recovery was investigated in immobilized Streptomyces viridochromogenes. These immobilized cells adsorbed, uranium readily and selectively. The immobilized cells recovered uranium almost quantitatively and almost all uranium adsorbed was desorbed with 0.1 N Na2CO3, These results showed that microbial cells are more stable after Immobilization and can be used repeatedly for the process of uranium adsorption-desorption. These results suggested that these microbial cells can be used for the recovery and removal of nuclear fuel elements, such as uranium and thorium, from refining effluents and mine waste water.

Jan 1, 1991

By Gennady I. Gulyayev

A mathematical model of plastic deformation occurring in cold plug drawing of mother tubes with initial cross-sectional wall thickness variations (CSWTV) has been developed. The main provision of the model is that eccentricity em is of such value that projection of all forces acting upon the plug in the deformation zone along the axis perpendicular to the drawing axis equals to zero. Calculations have proven that with other conditions being equal increase in the die cone angle and the deformation cycle number reduces CSWTV. Theoretical findings were confirmed by practical results. Keywords: cold, drawing, plug, die cone, plastic deformation.

Jan 1, 2003

By Juliana Gutiérrez-Paredes

Keywords: Slag, chromium oxide, recovery, stainless steel Experimental and theoretical work was performed to estimate the effect of slag basicity and amount of reducing agents on the reduction of chromium oxide from the slag which interacted with molten steel at 1600°C. The slag system contained CaO, MgO, SiO2, CaF2 and Cr2O3 together with Fe-alloys (Fe-Si and Fe-Si-Mg). The CaF2 and MgO contents in the slags were 10 mass % each; Cr2O3 was 25%. The amount of the ferroalloys ranged from 12.5 to 50 g per 100 g of slag. The (CaO+MgO)/SiO2 ratio was held at 1 and 2. The Cr yield was determined using both Fe-alloys as reducing agents. Some estimations were made to determine the theoretical effect of temperature, slag basicity, (CaO+MgO)/SiO2, and amount of reducing agents in the slag on the chromium recovery. The FACT (Facility for the Analysis of Chemical Thermodynamics) computational package is used to determine the equilibrium between the slag and molten steel.

Jan 1, 2005

By Dong Joon Min, Joo Hyun Park, Mi Sun Choi, Jae Hong Shin

Sublimation of ZrCl4 is important for the production of nuclear grade metallic Zr in Kroll’s process. The sublimation kinetics of ZrCl4 was investigated by TGA under both isothermal and non-isothermal conditions. The sublimation rate of ZrCl4 increased with increasing temperature under isothermal conditions. ZrCl4 sublimation was confirmed to be a zero-order process under isothermal conditions, whereas it was first-order kinetics under non-isothermal conditions. The activation energy of ZrCl4 sublimation under isothermal conditions was 21.7 kJ/mol. The activation energy for non-isothermal sublimation was 101.4 kJ/mol and 108.1 kJ/mol with the Kissinger method and Flynn- Wall-Ozawa method, respectively. These non-isothermal activation energies were very close to the heat of sublimation (103.3 kJ/mol). Sublimation occurs by two elementary steps: surface reaction and desorption. Therefore, the overall activation energy of ZrCl4 sublimation is 104.8(±3.4) kJ/mol. The activation energy of the surface reaction and desorption steps are proposed to be 83.1 kJ/mol and 21.7 kJ/mol, respectively.

Jan 1, 2014

By J. M. Shneerson

At Gipronickel Institute a technological flowsheet of pressure leaching of copper from rich copper concentrates (i.e. containing: Cu -59-75%; Ni -D.5-4.64%; Fe -D.2-J.3%; S -21.8-26.9%) was developed. As a result, the possibility of deep decomposition of copper-containing minerals with extraction of elemental sulphur (up to 90-95%) was established. The obtained sulphur concentrates contain 80-90% of elemental sulphur, which can be separated from sulphide residue through autoclave melting and settling. As a rule, sulphide concentrates remaining after extraction of sulphur contain up to 1-2% of noble metals. The sulphide concentrate can be purified to the level of rich concentrates or pure metals using the well-known methods as in the case of tankhouse slimes. The presented research specifies the parameters of main operations: pressure leaching and sulphur extraction. It was established that 98% of copper could be transferred into solution at temperatures of 108-1 10°C and oxygen partial pressure 0.4-0.6 MPa. Experiments were carried out in autoclaves of various volumes using the products of nickel matte processing.

Jan 1, 2003

By P .. R. Ammann

A two-stage pyrometallurgical process has been developed for the recovery of copper (and other non-ferrous metals) from copper smelter slags. All types of slags, including highly oxidized, converter-type slags, are cleaned in an electric furnace which employs mechanical mixers to promote magnetite reduction and copper extraction at high rates. In a 10-ton pilot furnace, it has been demonstrated that slags can be cleaned to 0.2-0.3 per cent copper with economically acceptable usage of raw materials and energy; copper is recovered as a high-grade matte. Pilot plant data have been scaled up to a commercial furnace and engineering designs have been made for a furnace to treat 60 tons per hour of slag from a Noranda Reactor and the associated converters. Plans are being formulated for the construction of a prototype slag cleaning furnace.

Jan 1, 1976

By Krishna Parameswaran

This paper illustrates sustainability considerations in copper hydrometallurgy using examples of practices at ASARCO LLC, an integrated U.S. primary copper producer. Using the classic Brundtland Commission development of sustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copper hydrometallurgical processes can be sustainable. The examples used to illustrate sustainable development and related concepts include: water conservation opportunities in milling and leaching operations; implementing green chemistry and promoting product stewardship in the electrorefining of copper.

By Wenxian Zhu, Patrick R. Taylor

"The small dimensions of nano-sized materials leads to novel and enhanced mechanical and physical properties. A thermal plasma reactor has been developed to study the formation of nanometer sized metal powders. A supersonic nozzle and a powder filter were designed and built. By vaporizing coarse metal powders in the plasma flame, and quenching the metal vapors through the nozzle at the rate of 107 K/sec, nanometric sized powders have been produced. The powders were collected in an airtight secondary quench-filter system. The particle size of the product power is 5 -20 nanometers, obtained through TEM analysis. The XRD analysis showed that the powder did not oxidize after the filter was handled in an inert atmosphere glove box.IntroductionNanostructured materials have been shown to exhibit improved physical and mechanical properties compared to conventional materials with larger grain sizes (1,2). There have been several methods proposed for preparing nanometer size materials. Thermally induced vapor-phase reactions have been used to produce a variety of powders. A common feature of these processes is the rapid production and cooling of condensable reaction intermediates and products, by gas-phase reactions, leading to the formation of a large number of very small particles. Thermal plasma synthesis of ultra-fine size particles has been attracting increasing interest (3,4,9-11), because it offers many advantages, especially in refractory materials processing, compared to conventional processes: (a) thermal plasma temperatures are very high(> 5000 K); (b) the rates of chemical reaction are much faster than those encountered in conventional processes; (c) high-purity materials may be obtained using fewer processing steps by collecting the product at temperatures where the by-products are in the vapor phase; ( d) the mean particle diameter can be controlled; (e) unifom sized particles may be produced with clean surfaces (these particles are particularly suitable for pressureless sintering); and, (f) high throughput per reactor volume can be achieved. In addition, the process used for generating particles determines the degree of sintering ability of the powders, since the process dictates the morphologies, the purity and its size distribution. In the future, thermal plasma synthesis nanometer size particles may play an important role in vapor phase reaction techniques and might be expected to be one of the first full scale commercial installations in the future."

Jan 1, 1998