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By Do-Hyeong Kim, Tae-Jung Kim, Seung-Yeon Won, Jong-Jin Pak, Min-Kyu Paek

Liquid iron alloys containing V, Mo, and Ni can be produced by the carbothermic reduction of spent catalysts used in petrochemical industry. Thermodynamics of carbon in these alloy melts is important for refining these alloys. In the present study, the carbon solubility in Fe-V, Fe-Mo, Fe-Ni, Fe-V-Mo, Fe-V-Ni, Fe-Mo-Ni and Fe-V-Mo-Ni alloy melts of various compositions was measured at 1873 K. The temperature dependency of vanadium effect on carbon solubility in liquid iron was also measured in the temperature range from 1823K to 1923K. The additions of vanadium and molybdenum significantly increased the carbon solubility in liquid iron alloys while nickel decreased the solubility. The experimental results were thermodynamically analyzed using Lupis’ relation at constant activity to determine the first- and the second-order interaction parameters of vanadium, nickel and molybdenum on carbon at carbon saturated condition. Using thermodynamic parameters determined in the present study, the carbon solubility in Fe-V-Mo-Ni alloy melts of various composition were accurately predicted and verified experimentally at 1873 K.

Jan 1, 2014

By S. Neven

The smelting of copper anode slimes, a material which contains mostly lead, silver, copper and selenium, has been practiced for many years with a view to recovering the silver and associated small amounts of gold. However, a theoretical understanding of the process has been lacking and this handicaps efforts to improve and intensify smelting operations. In the past few years work has been done in this area and this work will be reviewed in the paper. The underlying thermodynamics of the oxidation of silver-copper selenide mattes has been developed and used as a basis for the construction of a computational thermodynamics model which attempts to predict the composition of all condensed phases during the course of smelting. The model will be outlined and its successes in matching experimental data, as well as its current deficiencies, will be considered. Supporting work on the thermodynamics of silver solubility in slags, on activity-composition relationships in the Ag-Se system and work in progress on the oxidation state of copper in the slags will be reviewed. These projects are designed to provide further detailed data which will improve the robustness of the thermodynamic model.

Jan 1, 1999

By De-wen He

The distribution of persistent organic pollutants in the environment is studied using the multimedia environmental fugacity model, and environmental health risk assessment of POPs nearby a copper smelt enterprise is carried out. The result indicates that all are in an agreeable risk level without exception. The annual individual chronic risk index of HCB is 7.50×10-11. The annual individual risk index of 3,3',4,4'-TCB is 1.57×10-9, and the annual individual risk index of 2,3,7,8-TCDD is 6.57×10-9.

Jan 1, 2009

By Liu Chunpeng

Under an inert atmosphere, the temperature enhancement of nickel bearing pyrrhotite irradiated by microwave was measured with a special metal-sheathed thermocouple and the non-isothermal rate equations were obtained. Under the controlled oxygen potential of the reacting gas in the microwave field, over 90% sulfur contained in the pyrrhotite is converted into elemental sulfur directly, the iron and the nickel are transformed into FeO,, NiO, NiFe,O, and FeSiO,. According to the experimental data the rate of the elemental sulfur produced is in diffusional control and the non-isothermal equation derived is

Jan 1, 1993

By Hiroyuki Sano

A closed recycling process for the low-grade scrap of Al-based composite materials was developed. In this process flux treatment with water-soluble halide is a key technique. In the present work, flux treatment conditions were discussed from the viewpoint of the separation and the recovery of the base material, reinforcement and flux. Optimum separation condition was obtained for the NaCl-KCI-KF flux treatment. The recovered aluminum alloy can be recycled for various usages. The recovered SiC particles cannot be reused as reinforcement because of the coexistence of the contamination, therefore it is necessary to eliminate these contaminates or to find another use. The recovered flux is reusable with supplemental addition of fluoride.

Jan 1, 2003

By J. A. Holmes

Due to varying and complex mineralogy, the flotation tailings from the Chingola Concentrator have, for some years, contained upwards of 0.4% acid soluble copper. In 1968, an investigation was initiated, to determine a method for recovering this acid soluble copper. This initial investigation concluded with a recommendation to install a leach-solvent extraction-electrowinning plant at Chingola, to treat up to 900 000 tonnes of material per month, for an additional copper production of some 4 500 tonnes per month. The process consists basically of six stages :- Materials reclamation handling and preparation, acid leaching in air agitated pachucas, solid-liquid separation by countercurrent washing in thickeners, solution concentration and purification by solvent extraction, copper recovery by electrowinning, and residue neutralisation and disposal. This paper describes the development of the main parameters for design of each of the six sections, and gives details of the final plant design. Problems encountered in commissioning and initial operations are commented on, particularly insofar as they indicated any errors or misjudgements in the design. The choice of materials of construction is commented on in some detail.

Jan 1, 1976

By H. Y. Sohn, S. PalDey

"Fine particles of nickel aluminides and Ni4Mo were synthesized by reducing mixtures of, respectively, A1Cl3 + NiC12 and NiC12 + MoC12 vapors with hydrogen. Though thermodynamically favorable, the coreduction of NiC12 and A1Cl3 by H2 to form Ni3Al did not readily happen experimentally. The addition of a small amount of aluminum vapor was needed to initiate the coreduction reaction. The product particles as observed by TEM were very fine but usually agglomerated. The electron diffraction pattern of particles identified NiAl and NiA13 along with Ni3Al and metallic Ni. The content of Ni3Al was maximized at 52 mol% at 1050°C under the partial pressures ofH2, A1Cl3, and NiC12 at 57, 1.4, and 0.5 kPa, respectively. When a mixture of NiC12 + MoC15 was reduced by hydrogen, Ni4Mo particles with some Ni or Mo particles were obtained, the maximum content of Ni4Mo obtained being 93 mol % . The particle size was in the range of 100 to 200 nm. An Ni4Mo coating of 700 nm thickness on an Ni substrate was also prepared.IntroductionThe search for new high-temperature structural materials has stimulated much research on intermetallic compounds. Nickel aluminides have low densities, relatively high melting points, and good high-temperature strength properties. They show an increase, rather than a decrease, in yield strength with increasing temperature (1). Ni4Mo is also of interest as a high-temperature structural material. The major shortcomings of these intermetallics are their inherent brittleness at room temperature when they are in polycrystalline form. For much the same reason, the conventional casting of intermetallics is difficult. Ingot metallurgy and powder metallurgy are two other processing techniques. The first technique is quite energy consuming. In powder metallurgy, the powders of metals and alloys are consolidated in near net shape and then subjected to secondary processing. It would, therefore, be advantageous if intermetallic compounds can be produced in fine powder form from inexpensive raw materials, using less energy."

Jan 1, 1998

By G. B. Harris

Much has been written over the past decade concerning the disposal of arsenic from metallurgical processes. In Canada, there are proposed regulations which would classify arsenic in the Primary Group of twenty one persistent, toxic pollutants to be banned or phased out. Since many nickel and cobalt ores, not to mention those of copper, gold and uranium, contain significant amounts of arsenic, it is pertinent to assess the current state-of-the-art of its disposal. The literature is reviewed, and it is demonstrated that from a purely chemical point of view, the family of ferric arsenates largely immobilize arsenic. There is clear evidence from laboratory studies that both crystalline ferric arsenate (scorodite) and amorphous ferric arsenates in which the molar Fe/As ratio is at least three (Fe/As = 3) have very low arsenic solubility; plant data are given to support this. The debate over the long term stability of these compounds continues however; the evidence presented for long term stability and for compound breakdown is critically reviewed in the light? of the recent structural studies, and the role of base metals in these compounds evaluated. Finally, conclusions are drawn as to the viability of a purely chemical process for the long term disposal of arsenic from metallurgical processes.

Jan 1, 1993

By Chris Doyle

From 1997-2000. PT INCO undertook the Fourth Line Expansion Project (FLEX) to increase annual production rates from 90-100 to 150 Mlbs Ni/year (68,000 MT Ni/yr). In 2003, PT INCO nickel production underwent a major sustainable step jump that finally exceeded the targeted rate. This paper presents the changes that led to this achievement. The focus of mining changed. Improving Ni grade was important but only if electric furnace feed met target chemistry so that on-specification slag could be produced. The intensity of diamond core drilling for exploration was dramatically upgraded, mine planning strategy was totally re- vamped and an ore chemistry quality assurance team was formed. In the processing plant, measurement systems were upgraded for better control. Teamwork between sections vastly improved. The final step jump in production occurred when the fifth hydro-electric power generator was added to the furnace grid to allow the power-starved furnaces to cruise in operation at 70+ MW. Keywords: Free cash flow, Ore Chemistry, Measure, Control, Improve

Jan 1, 2004

By Pesic. Batric

A novel chitosan-pyridoxal-epichlorohydrin was synthesized and evaluated in our laboratories. The evaluation was achieved by performing kinetic and equilibrium studies of copper sorption. The parameters examined were pH, temperature, concentration of copper, particle size and selectivity of copper sorption against iron, zinc, cadmium and cobalt. It was found that pH was the most important parameter, and sorption of copper increased with pH increase in the range pH 2.5-6.0. The low activation energy of the sorption reaction, 1 1.13 kJ/mole (2.66 Kcal/mole), showed that temperature was not an important parameter. The synthesized chitosan was selective against iron, zinc, cadmium and cobalt. The selectivity with respect to last three metals was achieved by the kinetic difference of sorption, as sorption of copper was much faster than for other metals. Iron (Fe2+) does not adsorb on chitosan. The mechanism governing the sorption of copper is intraparticle diffusion. This finding was supported by the dependance of copper sorption on the square root of time, the low activation energy, and the fit of experimental data in the diffusion through the product layer equation.

Jan 1, 1994

By Cesar Garban

The samples of the washings are characterized of the ore for physical, chemical and metalurgical properties for representivity. the optimum values are determined for the recuperation of gold of the washings of the gold ore from the zone El Callao, Venezuela by acidic solutions of thiourea of the following parameters: Ph , contact time, composition of the liquid mixture, ratio of solid to liquid, grade of liberation, in an apparatus designed for contacting solid powder of the mineral with liquid solution of thiourea mantained in suspension by bubles of compressed air. The experimental results showed that the velocity of lixivation in primier time of (20) minutes is rapid and practically 2/3 part of the reaction is completed. For experimental design of parameters, the optimum conditions of recuperation of gold determind in this experimental investigation are:

Jan 1, 1999

By Niloy K. Nath

Two layer sintering by charging green sinter mix with normal coke rate in the upper layer and reduced coke rate in the lower layer, can substantially reduce the coke rate and also improve the sinter quality by producing more uniform thermal profile through out the bed height. The two-layer sintering process have been analyzed by numerical simulation of the process by a detailed CFD based model, considering all the important phenomena like gas-solid reaction, melting and solidification, flow through porous bed, heat and mass transfer etc. Optimization techniques like genetic algorithm, differential evolution is then applied to evaluate the optimum coke rate in the two layers of the bed to produce the ideal thermal profile and melting fraction in the sinter bed for optimum sinter quality. Through this optimization method both high quality sinter with minimum return fines can be achieved along with reduced coke rate. Application of a genetic algorithm for this type of process optimization has several advantages over the traditional optimization techniques since it can identify global optimum condition and perform multi-objective optimization much easily for complex industrial process like iron ore sintering. Keywords: Two-layer Sintering, Iron Ore Sinter Quality, Ergun's Equation, Gas-solid reaction, Melting Fraction, Multi Objective Optimization, Pareto Set, Genetic Algorithm

Jan 1, 2003

By Zhao Guangwen, Wu Tan, Qiuzhan Tian, Duan Shuzhen

"A thorough study of lost currents in bipolar cells has been made for the development of the great potential of bipolar cells in energy saving. A proper equivalent circuit for bipolar cells has been found, and mathematic methods for computing lost currents at all kinds of polarization have been developed.At linear polarization, the lost currents can be computed by solving either a tridiagonal matrix or an ordinary differential equation of second order. This kind of values can be used to evaluate the minimal lost currents at given conditions. At other kinds of polarization, the lost currents can be computed by the same methods as above if the necessary experiments of measuring the cell voltages of every electrolytic compartment have been made. This kind of values can be used to design bipolar cells at practical conditions.Extensive experiments have been made to evaluate the effects of electrode polarization, emf of galvanic cell for the formation of electrolyzed substance, gaseous products, geometric dimensions of electrolytic cells, special resistance of electrolyte used, and the total and ordinal number of electrolytic compartments on lost currents. It is the first time to make such a systematic research by experiments in the world. Experiments showed that theoretic models were in good agreement with measured data. Experiments also showed that D.C. energy consumption of 0.45 kwh/kg of Pb for lead electrolysis from molten chlorides could be achieved in a cell with 7 bipolar electrodes.IntroductionIt is very promising to apply bipolar electrolytic cells to electrolysis of aluminum, magnesium, lead, zinc and perchlorinates for their great potential of energy saving for example, bipolar cells had been used in the production of magnesium and saved more than 30% of energy, being one of the three main techniques of energy saving in the production of titanium sponge (1)."

Jan 1, 1988

By Zhigeng Xu

Pressure leach of a Yunnan marmatite concentrates with adding coal as the elemental sulfur disperser was investigated. The experimental results show that the coal with carbon content higher than 70% is incapable of dispersing elemental sulfur from minerals and cannot improve the leaching of zinc. The coal with low carbon content (lignite coal) can act as excellent sulfur-disperser in the pressure leaching at 423K. The mechanism of lignite coal as sulfur disperser was further discussed by ultraviolet, infra-red spectrum and mass spectrum.

Jan 1, 2008

By Y. A. Chang, L. M. Pike, C. R. Kao

"Knowledge of the site preference of ternary solute additions is essential to developing an understanding of how these solutes affect the properties of B2 intermetallic compounds. A quasichemical model will be presented which is able to predict the site preferences of dilute solute additions to tliple defect B2 compounds. The only parameters required are enthalpies of formation at the stoichiometric composition. General equations are developed which can be used to determine site occupations and defect concentrations for dilute as well as non-dilute solute additions. These equations use atom pair bond enthalpies as the parameters. It is found that the site preferences of dilute additions are not always in agreement with predictions based on the solubility lobes in ternary Gibbs isothelms. Predictions for dilute additions to NiAl and FeAl are compared to expel1mental results found in the literature. Satisfactory correlation is found between the model and the experimental results. In addition, the predictions from the model on vacancy concentrations in Fe doped NiAl are compared to recent experimental results by the authors.1.0 IntroductionIntennetallic compounds with the B2 crystal structure such as NiAl and FeAl have been investigated recently for possible use as structural materials in high temperature, oxidizing, and/or corrosive environments. The major limiting property of these materials has been a lack of sufficient room temperature ductility. Attempts to improve the ductility have often been made through ternary or higher order alloying. For B2 compounds, substitutional alloying additions can occupy either of the two sublattices and this site occupancy can be crucial in determining how the alloying addition affects the properties of the alloy. In this manuscript we will discuss the use of thelmodynamic modeling to predict the site occupancies of ternary alloying additions in B2 compounds with the triple defect structure."

Jan 1, 1996

By Jin-tao Gao

In order to recover Ti resource from titanium bearing blast furnace slag, a new technology to separate perovskite phase from CaO-TiO2-SiO2-Al2O3-MgO system by supergravity is researched. In the condition of gravity coefficient of 750g, treatment temperature of 1305°C and time of 20min, the significant layers appear in samples which are obtained by means of centrifugal treatment. Along the direction of the supergravity, the volume fraction of perovskite phase increases gradually, and the equivalent diameters of perovskite phase crystals increases with the area approaching to the bottom of the sample. It is indicated that TiO2 is enriched in the bottom of sample as concentrate with a recovery ratio of 74.05% by supergravity treatment.

Jan 1, 2014

By William Petruk

The primary requisite for a successful extractive metallurgy operation is to grind an ore fine enough to liberate the minerals so that they can be concentrated, or to expose mineral surfaces so that the minerals can be leached. The ease or difficulty of liberating or exposing the mineral grains is dependent upon the mineral textures such as grain size, crystallinity and bonding between mineral grains. In particular, mineral grains with straight grain boundaries and a weak bonding to other minerals are easily liberated and readily concentrated into high grade concentrates. In contrast mineral grains that have re-entrant boundaries and are strongly bonded to their neighbours are not easily liberated and will not produce high grade concentrates, even with regrinding. Similarly, inclusions that occur along fractures and grain boundaries can be readily exposed and leached. Whereas minute random inclusions in large grains will not be liberated or exposed unless they occur along planes of weakness.

Jan 1, 1995

By Bemd. E. Langner

At Norddeutsche AfFmerie the CollaMat is an important instrument for controlling the activity of glue in copper electrolyte. Thanks to on-line measuring of the glue activity appropriate action can to taken in the event of sudden changes, such as an intemption in the glue supply, as well as long-term trends, such as continuously decreasing glue activity over days or weeks. Laboratory tests on the dependence of glue degradation on temperature have shown that relatively small increases in temperature of only 3OC cause the half change value of the glue degradation to reduce by 25 %. It is a similar picture with the sulphuric acid concentration in electrolyte. An increase in the acid concentration from 160 g/l to 200 g/l can - depending on the temperature - likewise result in a decrease in the half change value of up to 25 %.

Jan 1, 1995

By Guo Chen, Xuefeng Liao, Tu Hu, Shengzhou Zhang, Hongying Xia, Jinhui Peng, Libo Zhang

Pine nut shell is as raw material for preparation of high surface area activated carbon (HSAAC) by microwave induced KOH activation. The effects of microwave power, activation duration and KOH/C mass rate (R) on the iodine adsorption capability and activated carbon yield were investigated. Additionally the surface characteristics of HSAAC were characterized by nitrogen adsorption isotherms and SEM. The operating variables were optimized utilizing the response surface methodology and were identified microwave power 738W, activation duration 17 min, and R 4, corresponding to a yield of 46.28 % and an iodine number of 2154 mg/g. The key pore structure parameters of HSAAC such as the Brunauer–Emmett–Teller (BET) surface area and total pore volume were estimated to be 3819 m2/g and 2.09 mL/g, respectively. The findings strongly support the feasibility of microwave heating for preparation of HSAAC from spent pine nut shell by microwave induced KOH activation.

Jan 1, 2016

By Esperidiana A. B. Moura, Célio H. Wataya, Roberta A. Lima, Rene R. Oliveira

The purpose of this study was to investigate the mechanical, morphological and thermal properties of biodegradable composites based on aliphatic-aromatic copolyester/polylatic acid blends (PBAT/PLA blends) reinforced by açaí seed fibers, an abundant byproduct of the açaí fruit agro industry. The biodegradable polymeric composites were prepared by melting extrusion process using a twin-screw extruder machine. The fibers removed from the açaí seed were used as the reinforcement and PBAT/PLA blends as the matrix. The influence of the açaí seed fibers addition on properties of composites was investigated by tensile and impact tests, SEM, DSC, and XRD analysis. Correlation between properties was discussed. In addition, açaí seed fibers characterization by SEM, XRD and WDXRF have also been carried out. The addition of açaí seed fibers on biodegradable PBAT/PLA blends showed that it is possible to get interesting property gains in biodegradable polymer by using waste from renewable sources.

Jan 1, 2015