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By Purushottam Kumar

Keywords: Magnetostriction, magnetic properties, Pd(Fe,Co,Ni) single crystals Fe-Pd, Co-Pd and Ni-Pd alloy systems show appreciable magnetostrictive strains that are of interest for sensor applications. These systems exhibit congruent melting minima. In this work the magnetic and magnetostrictive behavior of congruent melting Fe-Pd, Co-Pd, and Ni-Pd compositions have been examined. The alloys examined include Fe-54.9 at.-% Pd, Ni-45.4 at.-% Pd, and Co-45 at.-% Pd. The paper describes the growth of bulk single crystals of these alloys using Czochralski technique. X-ray diffractometer was used to obtain rocking curves that were used to determine the [001] crystal direction. Magnetostriction in [001] direction was measured using strain gages. Magnetic properties were measured using a vibrating sample magnetometer. Ni-Pd showed the highest magnetostriction values among the congruent melting compositions. Magnetic and magnetostrictive behaviors of these alloy single crystals are presented.

Jan 1, 2005

By Hong Yong Sohn

Keywords: Barium sulfate, Barium sulfide, Environment, Kinetics, Pollutants, Sulfur dioxide conversion, Thermodynamics Nonferrous smelters and coal gasification processes generate sulfur dioxide streams, most of which are treated to produce sulfuric acid with the accompanying problems of market shortage and transportation difficulties. While the conversion of sulfur dioxide to elemental sulfur has many environmental advantages, no processes exist that are environmentally acceptable and economically viable. A method for converting sulfur dioxide to elemental sulfur by a cyclic process involving calcium or barium sulfide and calcium or barium sulfate without generating solid wastes has been developed. In this process, the sulfate, as the starting raw material, is reduced by a suitable reducing agent such as hydrogen to produce the sulfide, which is used to reduce sulfur dioxide producing elemental sulfur vapor and regenerating the sulfate. The latter is then reduced to reproduce the sulfide. This paper describes work on the BaS/BaSO4 system. Thermodynamic analysis and experimental results indicated that the BaS-SO2 reaction produces mainly sulfur vapor and solid barium sulfate and that the gaseous product from the BaSO4-H2 reaction is mainly water vapor. The rates of the two reactions are reasonably rapid in the temperature range 700-1050°C.

Jan 1, 2005

By Wang Shulan

The synthesis process of BaTiO3 from TiO2 and BaCO3 in the molten NaOH-KOH at 350oC was studied by the A.C impedance technique. The A.C. impedance of molten NaOH-KOH (xNaOH = 0.36) and the variation of the conductivity of the salt with time during the synthesized process were measured. The synthesized reaction of the BaTiO3 and the decomposition reaction of BaCO3 are fast and were finished in 10min. The interaction between TiO2, BaO and BaTiO3 and the molten salt was confirmed by the variation of the conductivity.

Jan 1, 2005

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 Wilson Acchar

The accelerated growth of urbanization processes and current environmental concerns brought to light the existing enormous quantity of construction and demolition waste (C&DW). Considering the frequent lack of adequate landfill areas available for the disposal of these materials, their use in the manufacture of ceramic products has been attracting a growing interest from researchers and is becoming common practice, with the consequent relief in public administration concerns for the C&DW appropriate management. This work describes the study of clay-based products added with C&DW collected directly from the construction industry. Samples containing up to 50 wt.% C&DW were uniaxially pressed and sintered in air in an electric furnace (950-1150 °C, 1 hour). Sintered test pieces were characterized by X-ray diffraction, apparent density, open porosity and flexural strength. The results showed that up to 50 wt.% C&DW can be added to the clay material, with no degradation in the final product properties.

Jan 1, 2009

By Fang Wu

The paper designs an extraction flow for the total recovery of nickel and cobalt and removing magnesium simultaneously from the cadthodic materials of the spent hydrogen-nickel and cadmium-nickel batteries. The separation of Co, Ni and Mg though P507 extraction .The extraction equilibrium pH is 4.5~5.0, ßNi/Co is 140~180, and ß Ni/Mg is 20~25; nickel and magnesium are scrubbed in two steps, in which the equilibrium pH of nickel and magnesium scrubbing is controlled at 5.0±0.1 and 4.4±0.1 respectively. The stepwise scrubbing technique is adopted to remove 94.5% of magnesium and to recover 99.45% of nickel and 95.35% of cobalt. During the integrated extraction and precipitation process the total recovery fraction of nickel and cobalt are 99.99% and 99.95%, and the recovery fraction of magnesium is 94.02%.The recovered NiSO4 and CoSO4 solution are enriched and crystallized.

Jan 1, 2009

By A. Broussaud

An original methodology has been developed for steady state simulation of selective grinding and mineral liberation in rod and ball mills. Three fundamental aspects of the methodology are presented successively : modeling ore texture, modeling grinding and its selectivity, and modeling mineral liberation. The methodology for modeling ore texture includes the conversion of 2D data into 3D reconstructed information and the use of the BILCO coherent material balance software. The models for grinding Simulation are classified into three levels, corresponding to three levels of available experimental data. All models account for grinding selectivity and for variations of engineering para-meters and operating conditions. An algorithm has been introduced to forecast mineral liberation, compatible with accurate simulation of selective grinding, which generates reasonable results.

Jan 1, 1987

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 Guangqing Zhang

The paper presents results of a systematic study of synthesis of titanium oxycarbide and its chlorination. Titanium oxycarbide was produced by carbothermal reduction of titania in hydrogen, argon and helium. Formation of titanium oxycarbide started at 1200°C in all gases. The reduction was the fastest in hydrogen. Formation of titanium oxycarbide in hydrogen was close to completion in 120 min at 1300°C, 60 min at 1400°C and less than 30 min at 1500°C. Reduction in argon and helium progressed at a similar rate and reached 90-95% after 300 min at 1400-1500°C. The chlorination of titanium oxycarbide was ignited at 150-200°C. Chlorine partial pressure and gas flow rate strongly affected the chlorination rate. Chlorination of titanium oxycarbide produced with carbon to titania molar ratio 2.5 at 235-400°C was close to 100% in 30 min.

Jan 1, 2009

By Christophe Thiébaut

Keywords: Pyrochemistry, Salts Treatment, Distillation The pyrochemical purification of metal generates spent salts. When this metal is an actinide such as plutonium, the slags cannot be discarded and are thus disposed in nuclear facility. In order to handle with these slags, the decision has been taken to reduce stored quantities. The development of a pyrochemical treatment is in progress in the CEA Valduc centre. The feed salt, typically composed of various Pu and Am species contained into monovalent or divalent chloride matrix, is first oxidized to convert the actinides into oxides. Then the chlorides are separated from the actinide oxides by vacuum distillation. Temperatures higher than 750°C for monochloride salts mixture NaCl/KCl and higher than 1100°C for divalent CaCl2 base salts, are required to produce an industrial flow of vaporization. Inactive qualification of the process for NaCl/KCl base salt has been carried out with lanthanide surrogates. Then, a pilot equipment, called distillator has been designed and built for production-scale distillation of NaCl/KCl and CaCl2 oxidized plutonium salts. Industrial flows of vaporization have been obtained with this pilot equipment : about 4 g/cm²/h for NaCl/KCl at 800?900°C and 1 Pa, and more than 1,5 g/cm²/h for CaCl2 base salts between 1000?1200°C at 0.1 Pa. The last step, now in progress, is the integration of the distillator into a glove box.

Jan 1, 2005

By Emmanuel N. Zevgolis

Energy required for roasting and smelting of a nickeliferous laterite ore by the rotary kiln - electric furnace process is investigated. From this work it comes that thermal energy is about 65% of the total energy needed and the rest is electrical. Also, 61.3% of thermal energy input in the roasting step (of all combustibles fed into the rotary kilns) is used for pre - heating, 11.6% for pre - reduction and the rest (27.1%) corresponds to the energy of the remaining carbon in the rotary kiln products (i.e., calcine, dust and coatings). Carbon entering the system is used as follows: 57.9% for combustion, 37.1% for reduction and the rest (5.0%) remains unburnt. Exploitation of energy from gases of both furnaces, as well as the higher possible reduction degree, the optimum temperature of the calcine and also elimination of the excess air in the rotary kilns, improve significantly energy balance and economics of the process.

Jan 1, 2006

By Rick Honaker

Rare earth elements (REEs) contained in coal and associated mineral matter exist in several forms including micro-dispersed minerals, ion adsorption onto clay surfaces, and chemically bound. Tests found that REEs can be effectively recovered from certain components of three coal sources by leaching under mild conditions followed by solvent extraction. A range of pH values were evaluated at solution temperatures of 25 and 75 °C. When using 1.2 M of sulfuric acid, nearly 85% recovery of the REEs was extracted from the middlings material collected from an operating plant. Acid leaching of a second middling source from another plant resulted in 60% of the total REEs being recovered under the same leaching conditions. Solvent extraction treatment of the leachate produced from six different coal sources resulted in products containing up to 50% total REEs from feedstocks starting with around 300 ppm.

By J. C. Huyhua

The effect or various oxidants on gold and silver dissolution in thiourea solutions (0.05 M in H2SO4) was studied using the rotating disc technique, a.t 2s c and 600 rpm. These studies were carried out at constant (4:1) initial molar ratio or thiourea to oxidant concentrations, to produce 50 % thiourea. oxidation. The initial dissolution rate of gold was approximately four times higher in the presence. of ferric sulfate (5.37 x 10-3mg cm-2 s-1) than in the presence of hydrogen peroxide (H2O2), potassium persultate (K2S2O3), or monopersulfa.te (KHS06). The dissolution rates for silver were considerably lower than gold for the same oxidants. Oxidation of thiourea in the presence of peroxygen and persulta.te compounds is a. fast reaction and it is completed in less than ten minutes. On the other hand, the oxidation or thiourea with? ferric.sulfate is slow, yielding a second-order reaction rate constant k = 6.09 I mol-1 h-1. Sulfur formation in the ferric thiourea system begins when ferric ion reduction approaches to completion. With hydrogen peroxide, sulfur is observed at lower thiourea concentration than ferric. Suifate. The presence of a large excess or free thiourea i.e., s to 20 % thiourea oxidation) retards sulfur formation and maintains favorable dissolution rates. Finally, carbon-in-leach experiments indicate that thiourea solutions a.re stable for several days, with ferric sulfate or hydrogen peroxide. The dissolution rates of gold and silver doubles in the presence or activated carbon when hydrogen peroxide is used as oxidant.

Jan 1, 1989

By Ryszard Prajsnar

During copper production in shaft and flash smelting processes at KGHM Polska Miedz S.A., lead bearing material of sulfide, sulfate, and oxide character is generated in forms such as slime from shaft furnace gas handling systems, converter dusts, and dusts from an electric furnace for copper removal from flash smelting slag. These materials are polymetallic concentrates of Pb, Zn, and Cu, with As, Cl, and Cd as impurities. Shaft furnace slime, containing. about 50% PbS and 15% bituminous substances, is the main lead-bearing material. At the Glogów copper mill, a new plant was commissioned in June 2001 to process 80,000 tonnes per year of lead bearing materials to produce 26,000 tonnes per year of crude lead. The plant consists of a feed conditioning system, three (3) rotary rocking furnaces with a capacity of sixteen (16) tonnes of lead feed fired with natural gas and oxygen-enriched air containing up to 45 vol% O2, and a gas handling system. The gas handling system includes a post-combustion chamber, a gas cooling chamber with Cl neutralization, gas mixing chamber, bag filter, and dry limestone scrubbing system for SO2 removal. The lead-bearing feed is smelted with five (5) wt% Na2CO3 and thirteen (13) wt% iron scrap at a temperature of 950 to 1050°C for three (3) hours. The smelting process consists of four (4) stages; feed drying, firing of gaseous hydrocarbons and solid coal from the feed, lead reduction from slag, and separation of molten products. The flow rates of natural gas and oxygen to the burners are controlled to ensure combustion of the bituminous material in the furnace. The process produces crude lead bullion containing (wt%) 0.1 to 0.5% Cu, 0.02 to 0.5% As, 0.05 to 0.07% Bi, 0.1 to 0.5% Sb, and 0.1 to 0.6%Sn. The process also produces a mixture of sodium silicate slag, Fe-Zn-Pb-Cu-S matte, and Fe-As speiss containing (wt%) 5 to 10% Pb, 2 to 6% Cu, 10 to 15% Zn, 1 to 3% As, 10 to 15% S, 0.5 to 3.0% Cl, 2 to 4% K, 4 to 7% Na, 20 to 30% Fe, and 5 to 10% SiO2. The dust is made up of PbO, ZnO, PbSO4, and PbCI2, KCI, and NaCI with a chemical composition (wt%) of 35 to 50% Pb, 5 to 15% Zn, 3 to 6% As, 4 to 8% Cl, 2 to 5% K, and 2 to 5% Na. The construction of the new lead production plant at the Glogów copper mill will process both current lead-bearing materials as well as lead-bearing material that have been stockpiled over the last fifteen (15) years to give a significant improvement in protection of the natural environment.

Jan 1, 2002

By Chang-Dong Li

Cadmium ingot and nickel powder were prepared by high-temperature distillation, solvent extraction and liquid phase reducing method with spent Cd-Ni batteries as raw material. The impacts of the temperature in the distilling stage, the concentration of H2SO4 in the leaching stage, the pH value in the extracting stage and the dosage of hydrazine in the reducing stage were discussed respectively. The as- prepared samples were characterized by the means of X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic absorption spectrometry (AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results showed that the recovering efficiencies of Cd and Ni reach 99.5% and 99.3%, and the purities of Cd ingot and nickel powder were higher than 99.90% and 99.80%, respectively.

Jan 1, 2009

By Theo Lehner

Turning matte into anodes continues to be an area to watch: for visitors to see pyrometallurgy in action; for metallurgists to keep up with modern smelting furnaces and ever increasing production rates; for management to remain profitable using more tools than taught in school; and for environmentalists to detect the last small clouds from the ever cleaner smelter. Current converting practices have been screened and analyzed, and today, converting and casting is a modern industry. An impressive, though typical learning curve of converter productivity may be detected. Local conditions such as availability and type of raw materials, products extracted, cost factors, etc., have stimulated the development of add-ons or even alternatives to the still dominant method of converting by Peirce-Smith technology. Turning blister copper into anodes follows a similar path, namely increased productivity and improved quality. We dare to predict that development will continue.

Jan 1, 2005

By Etsuro Shibata

The saturated solubility of chromium oxide and the valence of chromium in the slag are important matters when considering how to effectively utilize chromium-containing slags. The experimental data of various types of slags cited in the literature were arranged according to the optical basicity in order to evaluate the effects of the oxygen potential and the slag composition. The saturated solubility of chromium oxide and the Cr2+/ Cr3+ ratio tend to decrease with the increase of the optical basicity of the slag at an oxygen potential below 10.5 atm. However, at an oxygen potential of 0.21 atm, the saturated solubility and the Cr6+/Cr3+ ratio tend to increase with an increase of the optical basicity. A practical approach was suggested to reduce chromium in the stainless steel slag and simultaneously recover it as a ferroalloy by the direct smelting reduction of chromium oxide in the molten slag using some reductant in a small furnace.

Jan 1, 2003

By Oliver Zach

To know as much as possible about the condition of the refractory material (lining thickness, slag layer, build ups, ...) in an high temperature furnace is very important due to the safety and economic impacts. The new CONSCAN system offers the possibility to measure the inner surface of an furnace, and based on this results to calculate the thickness of the refractory lining, slag layer, build ups,.... The CONSCAN System provides this results as figures and graphics. This system is also working under hot conditions so it is not necessary to cool down the furnace. Based on these results the process control and the refractory lining concept could be optimized for maximum campaign life of the furnace.

Jan 1, 2006

By Susan Jacob

The heat of fusion of silver was measured using high temperature differential scanning calorimetry (HTDSC). Heating rate, sample mass, calibration standard and cover gas flow rate were varied to determine their impact on instrument accuracy and reproducibility. Good reproducibility was achieved in most of the runs. Accuracy was not satisfactory in most of the runs, though three runs gave results within 1.7%, 3.3% and 3.5% of the literature value, within the acceptable limits. A larger mass and higher heating rate tend to generate more accurate results.

Jan 1, 2006

By M. N. H. Khan

CSIRO has been experimenting with supersonic flows as a method of rapidly quenching metallic vapours. Cooling rates above 106 °C/s have been achieved. The supersonic flow conditions are achieved by adiabatic expansion of the vapour through a Laval nozzle into a vacuum chamber. This paper will describe the basic physics of the process, outlining computer fluid dynamic (CFD) modelling of flow in the nozzle, the effects of different flow conditions on the condensation process and discuss the practical design issues associated with operating supersonic nozzles. Results obtained from a CFD model of the nozzle, which compared two methods of incorporating condensation, showed that inclusion of condensation substantially changes the conditions in the nozzle. Most noticeably, the effect of condensation produces a region in the nozzle where the temperature remains almost constant.

Jan 1, 2006