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By Jens Kristen Laursen

In 1999, Molymex S.A. de C.V. (Molymex), Mexico. (a company wholly owned by Molibdenos y Metales S.A. (Molymet), Chile) decided to install the Haldor Topsrae Wet gas Sulphuric Aicd (WSA) process for cleaning of the 4-5% SO2 off-gas from their molybdenum sulphide master in Cumpas, Mexico to produce sulphuric acid. The decision to install a WSA plant was based on the successful operation of a WSA plant at Molymet's molybdenum sulphide roaster in Santiago, Chile since 1993. This paper describes the process layout of the Cumpas plant, the operating experience of the Santiago plant, and the, differences in. process design between the two plants. It will furthermore summarise the applications of the WSA process for other roasting plants and smelters within the non-ferrous. metals industry producing metals such as copper, lead, and molybdenum.

Jan 1, 2002

By R. W. Harnmack

Hydrogen sulfide generated by the anaerobic respiration of sulfate-reducing bacteria was used to treat pH 2.2 water from the abandoned Rio Tinto copper mine in Nevada. The untreated water contained 550 mg/L Fe, 140 mg/L Al, 90 mg/L Cu, 80 mg/L Mn, 60 mg/L Zn, 4 mg/L Co, and 2 mg/L Ni. The bench-scale treatment system examined consisted of a bioreactor for H2S generation and three precipitator/clarifier units for metal sulfide precipitation and recovery. The treatment system reduced the concentrations of all metals except Mn to less than 0.1 mg/L. Manganese concentrations were reduced by 96 percent to 3.3 mg/L. A CUS/SO concentrate (33 pct Cu) and a ZnS/5° concentrate (28 pct Zn) were produced that may be suitable for metal recovery at existing smelters

Jan 1, 1994

By Dexter G. Mendoza

To analyze the behavior of minor elements in the copper smelting process, the phase relations and the activities of arsenic and antimony in the miscibility gap of Cu-Fe-S-X (X = As or Sb) system have been determined at 1473K by the quenching method and the double Knudsen cell- mass spectrometric method, respectively. The experiments have been conducted for the charges in the miscibility gap with different mass%Fe/mass%Cu ratios with varying arsenic or antimony content. The activity measurements indicate that the arsenic activities in both the metal and matte phases show extremely negative deviation from the ideal behavior. The Raoultian activity coefficients at infinite dilution in the metal and matte phases are found to be almost constant against the charges in the miscibility gap, and they are 4.3 x 10-3 and 5.5 x 10-2 for the metal and matte phases, respectively. Moreover, the activity measurements of antimony show an activity value larger than that of arsenic but it still deviates negatively from Raoult's law. The activity coefficients of antimony at infinite dilution are found to be 1.2 x and 2.2 x 10-1 for the metal and matte phases, respectively. The vapor pressures of the predominant As, AS2, AsS, Sb, Sb2, and SbS species in the gas phases of arsenic and antimony, respectively, equilibrated with the immiscible solutions have been calculated on the basis of the determined activity coefficients and they are very small at less than 1 Pa, even when their contents in the metal phase are increased up to 10 mass%.

Jan 1, 2002

By Hang Goo Kim

A mathematical analysis based on equilibrium modeling has been developed to describe the distribution behavior of minor elements such as Pb, Zn, Bi, Sb, and As among gas, slag and recovered copper phases during the reduction of copper oxide in slag cleaning with CO gas. The results show that large fractions of the impurities transferred to slag during smelting or converting are recycled to the recovered copper metal. It is also shown that there is a limit to the recovery of copper from slag because iron oxides are also reduced to form a copper-iron alloy at low oxygen potentials. The effects of various operating parameters such as temperature, the activity of FeO, the initial amounts of the elements in the slag and CO content in process gas, on the behavior of these minor elements are discussed. The predicted results were compared with the results of a pilot plant operation in which pulverized coal was used as a reductant. Consistent trends between the two cases were obtained.

Jan 1, 1992

By G. T. Lapidus

One of Society’s major concerns with hydrometallurgical processing is the large amount of water that is quintessential to its nature. This is especially troubling in arid areas, where the population struggles to procure potable water for their daily needs. For that reason, it has become our responsibility to conceive, design and implement processing schemes that not only use as little water as possible, but recycle streams within the plant itself and minimize waste that exits its perimeter. With this in mind, the conference will center on the importance of selecting the appropriate chemical systems and integrating material balances to avoid reagent overkill and to detect impurity accumulation. The three “R’s” (reuse, recycle and recovery) of aqueous solutions within the processes are emphasized. Examples of processes for the recovery of lead, copper, precious and PG metals from minerals and waste materials will be presented.

By Zheng Wei, Jian Cheni, Zhenliang Weng, Wei Liang, Hongbo Zhu, Jinhui Peng, Linqing Dai, Qianxu Ye

"By testing the dielectric constant and the dielectric loss factor of concentrated Dahongshan, mill scale, anthracite and light-burned dolomite in different frequency and temperature, and by studying the temperature-rising characteristics of the materials in the microwave field of 2.45GHz in frequency, the research in the paper shows that to reach at 1250°C under the same condition -2KW the microwave power and 30g the mass --the time concentrated Dahongshan takes is 330s, whereas the millscale is 855s and the anthracite is 820s. About the last one, the higher the temperature is, the stronger the absorptivity is. After the temperature has rose to 400°C, the anthracite's absorptivity increases dramatically. The result of the research would serve as the foundation of the further study on making direct reduced iron by microwave heating.1. IntroductionUnder the microwave fields, materials' dissipation of dielectric bodies would generate thermal effect. Therefore, the dielectric constant and the dielectric loss factor are closely related to materials' ability of absorbing microwave energy-the larger the dielectric constant and the dielectric loss factor are, the stronger the material's ability of absorbing microwave energy is, and the better the thermal effect would be[1-2]. In order to research how to make reduced iron from iron ore fines by microwave heating deeply and systematically, the test of raw materials' dielectric constants and dielectric loss factors are of the essence. What's more, because a mineral' conductivity is influenced by its components and crystal structure[3], it is necessary to study different materials' different temperature-rising characteristics; hence such studies would provide theoretical foundation of further research."

Jan 1, 2012

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Nathalie Neveux

For the first time, dehydrated ferrous sulfate was successfully used for the dry synthesis of potassium ferrate. In addition, ferrate ion is stabilized as a solid solution where hexavalent iron is partially substituted by S(V1) leading to a sulfato-ferrate having the following formula K2(Fe,S)04. This substance has an efficient life time of about six months. Ferrate ion is a powerful oxidant ( EO = 2.2V ), a bactericidal agent and possesses coagulant, flocculant properties. Its reduction generates nascent oxygen, hydroxyl groups and Fe(OH)3. Alkali metal ferrate is probably the future global agent for water treatment. Applications of this material in the field of urban and industrial effluents treatment have been investigated. Heavy metals cations such as Cu, Cd, Mn, Ni, Pb, Zn, ... were successfully removed. The results of sulfato-ferrate use for cyanide destruction, decrease in COD, soil, discoloration of pulp and paper effluents will be summarized.

Jan 1, 1999

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Pinakin C. Chaubal

Today?s steel industry is in a vibrant and resurgent mode. This transformation has been in the making for some time now. Over the last few decades, the industry was steadily transforming itself into becoming a high tech industry. New technology was adopted, efficiencies were enhanced, lean manufacturing concepts were brought in and a strong customer focus was developed. Today?s mills employ sophisticated instrumentation, computerized monitoring, on-line smart systems etc. driving processes that are producing at rates of many tons/minute. All this is not possible without judiciously using the latest available technologies in various fields and developing a more sophisticated work force. Prof. Sohn has been a pioneer in driving the concept of process engineering in process metallurgy. In this paper the focus is on some aspects of process engineering ? primarily process modeling - as applied to iron and steelmaking processes. Examples are shown to demonstrate how problems have been addressed. Some thoughts on future directions are presented.

Jan 1, 2006

By Jared Ball, Benjamin Hogg

There are over 100 process parameters that can be monitored during a single Peirce-Smith (PS) converter batch operation. To support a consistent operation it is important to select the correct Key Performance Indicators (KPI’s) to monitor. They should be strategically chosen to drive the desired behaviour with enough flexibility to endure process variations. At the Xstrata Copper Smelter in Mount Isa most of the PS converter operators have very little experience and are often lacking in the appropriate education or training to properly understand the process. For this reason 10 simple KPI’s were chosen that could be easily comprehended and monitored by all smelter personnel. KPI compliance has been supported by relevant project work in the converter area. Charge sequence trials have been performed in an effort to reduce splash and optimise activity time. The online measurement of full and empty ladle weights has enabled an immediate indication of skull size, skim/slag carryover, and metal loss.

Jan 1, 2009

By S. G. Galbraith

We have used the principles of supramolecular chemistry to develop reagents to transport metal salts. These reagents have separated charged "compartments" which recognize a metal cation and its attendant anion(s). They are easy to manufacture as they are structurally related to the commercial hydroxy-oxime extractants for copper. Efficient protocols for loading and stripping of these extractants depend on the novel feature that they bind the metal salt in a zwitterionic form of the ligand. Transfer of the phenolic protons to the pendant amines generates the charged "compartments" to accommodate the metal cation and its attendant anion(s). This paper focuses on how these types of reagent can be used to recover base metals from sulfate and chloride media in flowsheets in which solvent extraction effects separation and concentration operations, interfacing between conventional leach and electrowin/reduction processes. Work on the development of reagents that have high selectivity for metal chloride/sulfate transport, convenient stripping protocols and appropriate hydrolytic stability will be described.

Jan 1, 2003

By Bin Xu, Qian Li, Yong-bin Yang, Tao Jiang, Jian-jun Hu

It could significantly increase the leaching rate of refractory gold concentrate containing sulfur and arsenic by roasting pretreatment with adding certain amount of sodium sulfate, and the mechanism of that was systematically researched with DSC, XRD and SEM in this paper. Results indicated that the mechanism of Na2SO4 on double refractory gold concentrate at roasting pretreatment can be summed up in the following three aspects：Firstly, Na2SO4 can react with SO2 and SO3 which is produced by the oxidation of sulfides and generate Na2S2O7(l), which plays buffer effect on sulfides exothermic oxidation, avoiding the secondary-encapsulated of gold. Secondly, the liquid phase of Na2S2O7 can cover mineral particles' surface that possesses a sintering effect, it leads to internal cracks of the particles. Finally, mineral particles will gather with sodium sulfate particles as the center that can improve the permeability of the layer.

Jan 1, 2015

By Shadia J. Ikhmayies

"Nanocrystalline CdS thin films were prepared by vacuum evaporation on glass substrates at ambient temperature. The films were characterized by recording and analyzing their transmittance, X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) images and Energy dispersive X-ray (EDAX) spectra. X-ray diffractograms revealed that the material is nanocrystalline with predominant cubic crystal structure and preferential orientation along (1 1 1) plane. SEM micrographs confirmed the nanostructure of the material and showed uniform and well covered surfaces. EDAX reports revealed that the films are cadmium rich and contain oxygen. The first derivative of the absorbance was used to estimate the effective bandgap energies of the nanocrystallites and the hyperbolic band model was used to estimate their radii. The results were compared with those obtained by XRD and SEM measurements.IntroductionCdS thin films are of considerable interest as they can be used in fabrication of solar cells and other opto-electronic devices. In particular, heterojunction solar cells with a narrow band gap base and wide band gap window have been investigated in an attempt to develop efficient, stable and low-cost solar cells [1]. The CdS quantum dot embedded in a glass matrix is one of the well-known quantum dot systems and its electronic and luminescent properties have been studied extensively [2].Three-dimensional confinement of carriers within the quantum dots leads to the blue shift of the optical band-gap and to modification of many properties of semiconductor material [3]. It has been argued that in these semiconductor nanoparticles the hyperbolic band model gives a better fit to the observed quantum size effect as compared to the effective mass approximation [4]."

Jan 1, 2012

By Dengfu Chen, Huabiao Chen, Yunwei Huang, Mujun Long, Youguang Ma, Lintao Gui

In the current work, a three-dimensional model coupling turbulent flow, heat and solute transport was developed to investigate the solute transport and redistribution in the mold of slab continuous casting where the Reynolds number is very high and the molten steel flows strongly. The conservation equations of momentum, energy and species for a multicomponent system which includes solute element C, Si, Mn, P, S were solved with the commercial software ANSYS Fluent. The parameters used in the model are based on the actual continuous casting. The fluid flow, temperature distribution and solute elements distribution were analyzed. Results showed that negative segregation occurred near the strand surface, and the species concentration reached a peak value at the solidification front during solidification. The segregation degree of solute element S is higher than the other solute elements because of its lower equilibrium partition coefficient. The species concentration in the liquid pool is homogeneous because of the turbulent flow effect.

Jan 1, 2015