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By Mansoor Barati, Shaghayegh Esfahani

"The slag from extraction of ferrous and non-ferrous metals is a potential heat source which if treated properly can contribute to recovery of a significant amount of energy. The waste heat of slag may be used to generate steam, synthetic fuel gas, or electricity. Although several technologies have been investigated for this purpose, very little has been achieved in terms implementing the technology in industry. In this article, the development and application of various granulation techniques are reviewed and the methods to recover energy from granulated slag are discussed.IntroductionEvery year, more than 422 million tons of slag is being produced around the world as a by-product of the metal manufacturing at temperatures of up to 1300-1600°C [1, 2]. Currently slags are either disposed of or treated by processes such as granulation. Through the granulation process, most slags can be converted into a material which may be fully used as a cement feedstock. Conventional cement production is an energy intensive process with large emissions of CO2; therefore, the replacement can both be energy saving and environmentally friendly. However, for this purpose, the slag should have what is known as a “glassy” content (i.e. it should be amorphous) which requires rapid cooling rates that are not easily achieved due to the very low thermal conductivity. The main challenge in all these processes is to granulate the slag at a high cooling rate while the heat is also being recovered."

Jan 1, 2012

By Djalma Souza, Felipe Perissé Duarte Lopes, Frederico Muylaert Margem, Sergio Neves Monteiro

The development of composite materials is a combination of distinct materials, with applications in various areas, such as: aerospace, automobile, etc. Regardingmechanicalresistance,composites reinforced with a dispersion phase in a fiber form is more relevant. The green idea is use composites with natural fibers instead offiberglass, especially in non-structural applications. The Fique fiber has occupying an important place at Colombian agricultural and agribusiness sectors. Epoxy matrix composites reinforced with 1–6 Fique fabric layers were tested and the results indicated that thetensile properties improve with increasing theamount of Fique fabric layers. The fiber/matrix interaction was analyzed by scanning electron microscopy.

Mar 1, 2018

By Bingguo Liu, Daifu Huang, Jinhui Peng

"The conditions to prepare U3O8 by calcination from ammonium diuranate were optimized, and the response surface design method was applied to analyze the influence on the total uranium and U+4 of calcination temperature, calcination time and mass of sample. A quadratic equation model for the total uranium and U+4 of U3O8 was built and the effects of main factors and their corresponding relationships were obtained. The analysis of variance shows that calcination temperature and calcination time significantly affected the value of total uranium and U+4 of U3O8. The optimal calcination conditions were as follows: calcination temperature 931.83 K, calcination time 24.32 min and 43.89 g. Under these conditions the value of total uranium and U+4 of U3O8 was 84.78% and 28.02%, respectively. The validity of the model was confirmed experimentally and the results were satisfactory.IntroductionNuclear energy is clean, effective, and a sustainable from of energy. It plays an important role in overcoming the impending global energy crisis, and in reducing energy vulnerability. In addition, nuclear energy is a possible cheaper and cleaner source of energy compared to fossil fuels, with no not really, mining of uranium produces CO2 contribution to green house gases [1]. Uranium dioxide, one of the most important fuel pellets used as nuclear fuel in light water reactors, is manufactured by calcining ammonium diuranate to triuranium octaoxide, followed by its reduction to uranium dioxide using cracked ammonia at 700°C [2]. Earlier attempts to optimize the important calcination process through several common techniques have not yielded desirable results [3]. These techniques either rely on the classical one parameter at a time approach that ignores the combined interactions between physicochemical parameters, or are theoretical in nature. Furthermore, these techniques also require large number of experimental data to be generated [4]. In order to produce triuranium octaoxide in an optimized manner, which considers the interaction of different process parameters [5], there is a need to adopt a multivariate statistical technique."

Jan 1, 2011

By Du Sichen, S. Seetharaman, J. A. Bustnes

"The present study deals with the kinetic studies of reduction of some selected transition metal tungstates with hydrogen. The measurements were carried out by the isothermal thermogravimetric method. Shallow powder beds were employed in order to avoid the effects due to transport phenomena affecting the reaction rate. In this way, the chemical reaction rates could be selectively studied. The experiments were carried out in the temperature range 873 - 1173 K. From the experimental data, the activation energies were evaluated and were found to be around 88 kJ / mol in the case of both iron as well as cobalt tungstates indicating the similarities in W-O bonds in both cases. The activation energies obtained are discussed in the light of the position of the transition metal in the periodic table as well as the thermodynamic stabilities of the various tungstates.IntroductionThe tungsten containing hard metals, characterized by high density, belong to a class of two-phase metal matrix composites. While these types of materials have traditionally found their applications within the defence industry as armour-piercing projectiles, counterbalance in helicopters and military aircrafts, outer casings of hand-grenades, etc., commercial applications for this class of alloys also exist, including radiation shields, penetrators for the oil industry, turbines for turbo-jet engines and a wide range of sports related parts. A possible route to the production of these alloys is to reduce the tungstates such as FeW04, Co W04 and NiW04 using a reductant like hydrogen or carbon monoxide. In order to have a better understanding of the processes involved in the production, it is important to have a knowledge of the reduction kinetics for these tungstates. According to the knowledge of the present authors, while the reduction ofNiW04 by hydrogen gas has been investigated earlier in the present laboratorypl no systematic reduction study has been carried out previously for the tungstates of iron, cobalt."

Jan 1, 1996

By Kazue Moriya

At the 1980 TMS-AIME world symposium, Dr. Davey mentioned that the traditional lead blast furnace is now being challenged by direct smelting processes. In the copper smelting field both the blast furnace and reverberatory furnace are also disappearing in favour of direct smelting processes such as Outokumpu flash smelting, Mitsubishi continuous smelting, Noranda furnace, Inco furnace and so on. Those new processes all have the following in common: (1) High degree of mechanization (2) Metallurgical reactions carried out in closed vessels (3) Application of oxygen and/or oxygen enriched air (4) Minimization of handling materials and gaseous volume (5) Minimum energy requirements (6) Removal of workers from near the furnace (7) Reduction of emissions of harmful gas to meet environmental regulations. (8) Improvement to the work place environment to avoid occupational hygiene hazards. Direct and continuous smelting of powdered concentrate in one vessel was a romance of the metallurgist since early times. However as mentioned above, in the copper field this objective is being achieved in practice. The industry however can't deny that the serious and severe regulation of environmental pollution in every country was the prime motive for the modernization of smelters. In early days, to meet regulations, it was anticipated that many economic difficulties such as higher capital and energy costs and extravagant use of resources and waste disposal would be the result. "Turn a misfortune into a blessing" is an old saying which reveals the current thinking and reacent developments in the nonferrous industries. In the last ten years in the lead smelting field, about two decades later than copper, commercial scale smelting using new furnance technology has started. The KIVCET process and QSL process, which is flash smelting and bath smelting respectively, are becoming major competitors. They will be sure to upgrade their processes to remain economically and environmentally viable in the comming decade.

Jan 1, 1990

By Lloyd R. Nelson

Selective carbothermic reduction is the preferred method of treatment of electric arc furnace (EAF) dust (listed hazardous waste, K061). The process maximizes the recovery of recyclable constituents by concurrent production of saleable zinc metal (directly condensed from the furnace off-gases), an innocuous, disposable iron oxide-rich slag, and some metallic iron. Results of a mineralogical investigation of a foaming slag produced during selective carbothermic reduction treatment of EAF dusts are presented. Wiistite and tricalcium silicate were identified by reflected light microscopy as the primary crystalline phases contained in a glassy matrix, but this technique failed to reveal any solid phases that could have significantly contributed to foam stability. It was concluded therefore, that the foam had been unstable, and had been primarily generated by copious gas evolution associated with the sudden reduction of the slag by an inadvertent addition of carbonaceous reductant. This is consistent with the susceptibility to foaming, when subjected to sudden excesses of carbon, of the slags produced by selective carbothermic reduction, because they still contain unreduced components such as iron oxide.

Jan 1, 1994

By K. Fagerlund

Methods for simulation of settler reactions, matte-slag separation and matte settling in copper flash smelting have been examined. The reaction, separation and settling phenomena of slightly oxidized chalcopyrite samples and cuprous sulfide-magnetite mixtures in fayalite type slags were examined at about 1300°C under inert atmosphere. Two methods based on introduction of molten samples of oxidized chalcopyrite concentrates or synthetic matte-magnetite mixtures onto the surface of molten iron silicate slag were tested. In the first method the samples were water quenched and polished specimens were studied and analysed using light optical microscope, scanning electron microscope, energy dispersive spectrometer. In the second method processes taking place after the introduction of samples onto the slag are followed "in situ" using X-ray transmission image monitoring. Great differences were observed in separation and settling behaviour of low and high grade copper mattes produced as a results of interaction of initial samples and slag.

Jan 1, 1997

By D. J. Chaiko

Certain radionuclide ions (e.g., TcO4) exhibit unusually strong Affinities toward the polymer-rich phase in aqueous biphase systems generated by combinations of salt solutions with polymers such as poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG). Thus, aqueous. polymer ,phases could potentially be used to selectively extract these ions during pretreatment of radioactive tank wastes at Hanford. To help develop a fundamental understanding of the interactions between various ions and polymers in aqueous solution, interaction enthalpies between sodium -perrhenate and a random copolymer of PEG and PPG (UCON-50) were measured by microcalorimetric titration. An entropy compensation effect was observed in this system in which changes in enthalpic interactions were balanced by entropy changes such that the interaction free energy remained constant and approximately equal to zero.

Jan 1, 1999

By T. Ranki-Kilpinen

In the flash smelting technique, developed by Outokumpu Oyj, off-gases with dust load are directed into the heat recovery boiler (HRB). As the temperature decreases, metallic sulphates become thermodynamically stable. Sulphation of oxidic particles initiates. The release of heat causes an increase in particle temperatures, and soft sulphated particles can stick to the heat transfer surfaces. Dust accretion may form and cause operational problems. The objectives of the project are to study sulphation reaction mechanisms and kinetics of flue- dust particles under HRB conditions, and get more information for the flue-dust treatment possibilities. The sulphation behaviour of synthetic Cu2O particles (37-53 pm) was studied using a fluid-bed reactor of laboratory scale. The experimental parameters in the latest campaign were oxygen and sulphur dioxide contents of 2.5-10 vol-% 02 and 40-60 vol-% SO2 respectively and temperatures of 600-660°C. Samples were examined microscopically (SEM+EDS) and chemical analysis were conducted. The sulphation rate was found to have a maximum at the certain temperature, which was dependent on the gas SO2 content. Regardless of the level of SO2, a rise in oxygen content promoted sulphate formation.

Jan 1, 2002

By Katja Reinharter

Arsenic can be found in different sulfidic copper concentrates and residues, which for several years have commonly been used in copper metallurgy, as the “arsenic-free” resources are getting rare. Due to the high toxicity the removal of arsenic in the copper smelting process is a very important topic. The typical chemical slag and sulfur attack on the refractory material is getting enhanced by the presence of arsenic. This work deals with post-mortem investigations of a magnesia-chromite brick and castable used in copper smelting furnaces showing an additional and increased chemical attack by arsenic. The knowledge on the wear behaviour is not only based on a detailed chemical and mineralogical characterization, but also on thermochemical FactSageTM calculations, which are carried out on provided post-mortem samples. Post-mortem investigations on used refractory materials represent an important prerequisite for the product development, as well as for special engineered lining concepts to support our customers.

By Fabiola Alvarez, Ana E. Bote, Daniel Pasquevich

"The oxidation of aluminum and its alloys was extensively studied for improving the corrosion resistance in structural materials having high specific strengths. But this reaction involves the formation of a very thin barrier layer on the metallic pieces. Furthermore, the ·recent development of the directed melt oxidation process for producing metal-ceramic; composites has renewed the interest in the study of interaction between gases and metals. Oxidation experiments in the presence of different chlorine partial pressures and at different temperatures were performed in ·a thermogravimetric balance, and microstructures were analyzed by electronic microscopy and X-ray diffraction. The oxy-chlorination kinetics was determined and the oxide formed W(IS amorphous at temperatures below 600 °C and crystalline .at higher temperatures. The appropriate experimental conditions for the fastest completed oxidation was further determined.IntroductionThe use of fine powders for the manufacture of ceramic components has significant advantages. They include excellent sinterability; low sintering temperature and better microstructure leading to improved mechanical properties. The conventional method of producing fine oxide powders involves controlled precipitation and pirolysis of suitable salts. The main limitation of the high temperature decomposition route is the evolution of environmentally unacceptable and corrosive gases. Controlled precipitation of hydroxides from solutions of salts, followed by thermal treatment involves large volumes of solutions and the calcination step that can induce grain growth (1).Direct oxidation of aluminum metal for producing alumina powder requires high temperatures for the direct oxidation of molten Al alloys by a vapor phase oxidant process (2, 3) or high technological process like thermal plasma reactor ( 4).Oxidation of high purity aluminum (5, 6) below the melting temperature· is initially characterized by a nearly linear reaction rate, followed by a rate which decreases rapidly with further weight gain. However, the oxidation rate of an aluminummagnesium alloy is much faster and it does not conform to any common oxidation law, but it is nearly parabolic at temperatures between 200 and 400 °C, an nearly linear· above 400 °C."

Jan 1, 2000

By J. D. Miller

Air-sparged hydrocyclone (ASH) flotation is a high-capacity flotation technology originally developed in the Department of Metallurgical Engineering at the University of Utah for processing mineral resources. However, the technology has been found to be useful in industrial waste processing, in the recycle of secondary resources, and in remediation of environmental problems. For example, areas in which the ASH technology is expected to have potential application include cleaning of waste coal fines, air stripping to remove volatile organics from drinking and process water, water disinfection by ozone or chlorine sparging, dispersed oil removal from water, and contaminated soil remediation. Recently, the ASH has been studied extensively for deinking flotation in the wastepaper recycling industry and has been shown to have excellent efficiency/capacity. In fact, a 20-million-dollar plant has been in operation since June 1992. The ASH technology can provide a specific capacity hundreds of times more than that which can be achieved with conventional flotation equipment and in certain instances is expected to provide superior separation efficiencies when compared to other technologies. The design and principles of ASH flotation are described. Experimental data for fine coal flotation, volatile organics stripping, and deinking flotation for paper recycle are presented and discussed. Finally, other potential areas of application for environmental technology are considered.

Jan 1, 1993

By Liuyin Shi, Kang Liu, Fengqi Zhao, Yan Song, Zhiping Yang, Xing Fan

Due to the high energy consumption, long technical process, low usage rate of vanadium during the traditional smelting vanadium steel process, a new method for decarburization by CO2 to directly smelt vanadium-containing steel in blast furnace was proposed. In this paper, the thermodynamics of CO2 decarburization in molten iron process was calculated out by FactSage. The thermodynamic calculations indicated that in standard state, the transformation temperature of C and V was 1357 °C; the oxidation order of element was Si, C, V, Mn and S when using CO2 as oxidant. The experiment of blowing CO2 temperature showed that decarburization reaction temperature was 1550 °C, carbon content could be decreased to 0.676%, the decarburization rate was 88%. There was no effect on vanadium content in molten iron during the decarburization process, vanadium content was 0.323%, which meets the request of vanadium mould steel.

Mar 1, 2018

By R. J. Kuczynski

The U.S. Bureau of Mines Reno Research Center operated a batch pilot plant to demonstrate high-temperature cyanide leaching for recovering platinum group metals (PGM) from automobile catalysts. Approximately 1,600 kg of used pellet, monolith, and metal support catalyst containing 1,680 g (54 tr oz) of PGM were processed. Forty-five-kilogram batches of used catalyst were leached with sodium cyanide solution at 160° C for 1 h under basic conditions in a countercurrent processing sequence to dissolve the PGM. Extractions from the used pellet catalyst ranged from 94 to 95 pct for Pd, 95 to 97 pct for Pt, and 64 to 81 pct for Rh. Extractions from the used monolith catalyst ranged from 7B to BB pct for Pd, 75 to 90 pct for Pt, and 43 to 71 pct for Rh. Heating the pregnant leach solutions to 275' C for 4 h destroyed the PGM-cyanide complexes, resulting in over 99.7 pct of the PGM precipitating from solution. The PGM precipitate was predominantly a powder metallic concentrate, typically analyzing greater than 50 pct PGM. Heating destroyed cyanide to less than 0.2 mg/L. Both the pellet and monolith residues were evaluated for disposal using the EPA Toxicity Characteristic Leaching Procedure.

Jan 1, 1995

By Sunil G. Warrier

A rapid infrared forming technique has been developed to fabricate titanium matrix composites. This technique applies infrared heating to infiltrate titanium alloys into carbon and silicon carbide prepregs. The entire process typically takes 1-2 minutes in an inert atmosphere. The advantages of this technique are that the process is fast, simple, does not require a vacuum or a high external pressure. The process is very economical both in energy conservation and operation costs. This technique has been used to produce void free composites with limited, well controlled fiber-matrix reactions and mechanical properties comparable to currently available titanium matrix composites.

Jan 1, 1993

By J. W. Evans

Mathematical modeling has now become a standard technique in the development of new technology and the improvement of existing technology in the processing industries. Physical modeling has a longer history but a smaller following at present. The paper reviews some examples of the application of both types of modeling in non-ferrous metal extraction, particularly within the copper and aluminum industries. The objective is to show that well founded models can lead to results that have practical consequence in scaleup, design and operation.

Jan 1, 1993

By Ahmad-Bitar¸ Riyad N., Shadia J. Ikhmayies

"CdSi-xTex thin films with O<x<0.3 were prepared on glass substrates by the annealing of CdS:In thin films produced by the spray pyrolysis technique. The annealing was performed in nitrogen atmosphere at 400 --,C in the presence of Te vapor. The compositions of the films were determined by energy dispersive X-ray detection (EDAX) measurements. Scanning electron microscopy (SEM) was used to investigate the morphology of the films. The transmittance of the films was measured at room temperature in the wavelength range 400-1100 nm and used to produce the absorbance of the films. The first derivative of the absorbance was used to estimate the optical bandgap energy Eg by using the minima in the first derivative. The relation between the bandgap energy and the fraction x was found to fit with a parabola and bandgaps in the range 2.196: =Eg: =2.480 e V were obtained. Urbach tailing in the bandgap was also investigated.IntroductionPolycrystalline thin film CdS/CdTe solar cells are promising candidates for low cost and high efficiency photovoltaic applications. The fabrication process of these cells involves the deposition of a p-type CdTe absorber layer on top of an n-type CdS one which acts as a window. The efficiency of the solar cell is affected by the method of preparation of both layers [1, 2].Interdiffusion processes taking place at the CdS/CdTe interface have largely been realized to significantly affect the device performance [3] by changing the bandgap of both CdTe and CdS which modifies the spectral response of the solar cell [ 4]. The formation of a mixed crystal or a graded layer causes a reduction in the lattice mismatch at the CdS/CdTe junction [5] which is about 9% [ 6] and then a reduction in the number of interfacial states and recombination centers, thus enhancing the solar cell performance [7, 8]. A complete understanding of the properties of the intermixed layers CdSxTe1-x that usually constitutes the interfacial region in the CdS/CdTe solar cell is essential. According to our knowledge, a lot of research was devoted to the investigation of the diffusion of S into CdTe [3-5, 9]; but little on the direct investigation of the diffusion of Te into CdS [6]."

Jan 1, 2011

By Xu Weimin

The existing copper electrorefining tankhouse of Jinchuan Nonferrous Metals Complex (JNC) was commissioned in 1986 for refining blister copper anodes. Blister copper is produced by reverberating chalcocite separated from converter high grade nickel-copper matter by means of flotation. Special chemical analysis of the anodes shows, a composition of 93.02 - 95.72 % copper, 3.0 - 4.96 % nickel and 0.5 - 1.23 % sulfur. The wide range of composition makes the electrorefining process fairly different from others throughout the world. The initial nickel content of 20 ppm and sulfur 40 ppm or more in copper cathodes are reduced to 8.5 ppm and 11 ppm respectively. Since 1986 the tankhouse has undergone significant evolutionary modifications and implementations to ameliorate cathodes quality desirably. The important fact is that the N-additive was utilized through many studies and pilot and field trials successfully. While our primary purpose is to improve chemical quality of the cathodes, tankhouse capacity is increased considerably and the process is perfected satisfactorily. The tankhouse is described with special emphasis on JINCHUAN PROCESS. The upgrading of our product by the utilization of the N-additive is highlighted. The other aspects of the tankhouse including spent electrolyte treatment and by product nickel sulfate manufacturing are briefed as well. Key words: JINCHUAN PROCESS, anode, cathode, electrolyte, electrorefining, N-additive.

Jan 1, 1993

By Dachun Liu, Xuepeng Li

Smelting-acid leaching process is a way to treat high-content arsenic containing copper dust. However, smelting makes a low recovery of valuable metals and acid-leaching produces large amounts of arsenic-iron slag. Arsenic sulphuration volatilization at low temperature was studied, followed by pressure leaching to selectively recover Cu, Zn, and In from copper smelting dust while minimizing arsenic contamination.

Mar 1, 2017

By M. J. Collins

Direct pressure leaching of zinc sulphide concentrates was started? commercially in October 1980. Continuing research and development studies at Sherritt and feasibility studies for a number of clients have defined various pressure leach configurations for integrattons with existing roast- 1 each operations and for grass roots plants. Existing and potential applications of zinc pressure leaching are discussed.

Jan 1, 1990