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By J. C. DeSantis

Thin, highly reflective rhodium films with metal compositions greater than 98% (elemental -weight percentage) have been deposited by chemical vapor deposition using Rh(allyl)3 (ally1 = q3-C3H5) in the presence of a hydrogen plasma. Uniform, crystalline films that adhere well to several types of substrates result from depositions at temperatures as low as 150°C. Depositions using H2 (no plasma), or an argon plasma yields material that is amorphous, contains a significant amount (>14%) of residual carbon, and has a dramatically slower growth rate. The composition of these materials does not vary significantly from that of the materials obtained from the in vacuo thermal deposition with Rh(allyl)3.

Jan 1, 1992

By Gerardo Muñoz

All along this century CODELCO's smelters have been operating on conventional technology, which Codelco has streamlined by using oxygen, developing oxy-fuel burners for reverberatory furnaces and introducing oxygen smelting of concentrates in converters (Teniente Converters). Chuquicamata began capturing sulfur from its first Teniente Converter in 1985. Since then, it has implemented a program allowing to gradually increase such capture. In 1994 a Frame Law on the Environment was enacted in Chile. By virtue thereof and of CODELCO's corporate environmental policy, an investment program aimed at capturing more than 95% of gaseous pollutants in all its smelters in a term not exceeding twelve years was established. The above entails a substantial improvement of the operational management as regards fugitive gases capture and treatment. This paper describes the way CODELCO is to deal with this challenge with a view to fully complying with environmental regulations and obtaining the required environmental certifications of its operations.

Jan 1, 1996

By R. W. Lawrence

A method by which it is possible at an oxidation potential below 680 mV SHE to achieve quantitative conversion of sulphide sulphur to elemental sulphur instead of sulphate in a biological leach of chalcopyrite and bornite has been investigated. The process chemistry, biological phenomena and process flowsheet options are discussed. Several copper concentrates have been evaluated and have been found to be amenable to th process. Results to study the progression of chalcopyrite decomposition during the leach are presented and mineralogical factors affecting the requirement for silver addition are discussed. A chloride addition method for improving silver recovery is described. The results of a small scale continuous leach test have demonstrated that continuous operation can be carried out with high copper extraction and stoichiometric conversion of sulphide sulphur to elemental sulphur.

Jan 1, 1985

By Derek J. Fray

The need for on-line sensors is outlined and it is demonstrated that the control of many processes is prevented by the availability of these devices. The use of solid electrolytes is described for the sensing of elements in molten pyrometallurgical phases. In the cases where there is no suitable electrolyte, the addition of a second phase of a compound containing both the element to be measured and the element whose ion is mobile in the electrolyte can be used. For the measurement of high concentrations of an element a method based on current measurement is proposed.

Jan 1, 1994

By M. J. King

The Chino Smelter embarked on a program to reduce smelter emissions. Fugitive sulfur dioxide and particulate emissions were reduced by (i) removing the flash furnace settling chamber and (ii) installing a baghouse, to treat converter secondary emissions. Neutralization plant capacity was increased, to accommodate increased flow from the flash furnace off-gas cleaning system and to reduce costs.

Jan 1, 1998

By Joel Anderson

Allvac 718Plus is a newly developed superalloy with a good potential for use in fabricated aircraft engine structures when service temperatures exceed 650°C; the limit for standard alloy 718. Fabrication involves welding, where cracking usually is a prohibitive factor. Comparison of the solidification cracking behavior between these two alloys was made by Transvarestraint testing. It was shown that the total amount of cracking was significantly lower for 718Plus alloy, which was associated with a lower amount of ?/Laves or ?/NbC eutectic-type constituents. This in turn is believed to be due to the lower iron content of the Allvac 718Plus material. The analysis of alloying element segregation both within primary dendrite and interdendritic constituents clearly indicates that the segregation of Nb is the controlling factor in determining the final solidification microstructure in these alloys. The Nb concentrations of these constituents are significantly higher compared to the bulk alloy concentration. This was confirmed by the SEM-EDS analysis and calculations assessed with JMatPro, the latter also indicated that alloy 718 is more prone to form Laves and NbC eutectic-type constituents compared to Allvac 718Plus material.

Jan 1, 2008

By Jin Liu

In the early 1990?s, Inco successfully installed two new flash furnaces as part of their SO2abatement project to reduce SO2 emissions from the Copper Cliff Smelter by 60%. The flash furnace off-gas is cooled and cleaned through two new Monsanto Dynawave gas cleaning systems that replaced the traditional venturi scrubbing system. It was discovered that the flash furnace production capacity is often limited by the capacity of the gas cleaning system. The key task is to eliminate pressure drop from the system. The froth column is responsible for by far the largest pressure drop in the gas cleaning system. Initially, the column was fitted with 22 plates. In 1994, both #1 and #2 froth columns were modified by reducing the number of plates in each column from 22 to 18 and increasing the interplate spacing on lower plates. With increasing demand for more throughput in the flash furnaces, further modifications on the froth columns were made in 2005. This paper describes these modifications and results together with some fundamental analysis of the froth column characteristics.

Jan 1, 2006

By J. T. Stanley

The identification of crystal phases and crystal chemistry can be critical to understanding the mechanisms of waste material interaction with native soils. Understanding these mechanisms can suggest correct methods for remediation and treatment. A program is outlined and examples are given of the development of effective techniques for rapid phase identification of environmental samples using electron microscopy. The program concentrates on the development of integrated object oriented software to aid rapid searching of online databases and rapid simulation of potential crystal diffraction patterns. Examples come from dried sludge taken from a former hard-chrome plating facility.

Jan 1, 1993

By Xingming Zhang, Huawei Zhang, Yanxiang Li

"A hybrid porous metal with nano-micro double scale pore size and regular-random bimodal porous structure has been fabricated by unidirectional solidification of a lotus-type alloy followed by dealloying treatment to the base alloy. The base alloy selected is a Cu-Mn binary alloy. The lotus-type porous Cu-Mn alloy with straight pores of several hundred micrometers in diameter was manufactured by unidirectional solidification with a mould casting process. Dealloying treatment was then done to the lotus-type porous structure of Cu-Mn alloy. The solid Cu-Mn alloy wall of the lotus-type porous structure was transformed to random porous structure of dozens to hundreds nanometers. The influence of corrosion parameters, such as the current and time in electrochemical corrosion, temperature and corrosion agent in chemical corrosion, on the nano-porous structure formed has been studied systematically.1. IntroductionA hybrid porous metal is a kind of cellular structure with different porous or cellular forms inside, which possesses special properties and can be applied in many fields as fuel cells, catalysis, sensors, etc. Several means have been developed to fabricate this kind of porous material [1-2]. In this paper, a novel process of Gasar plus dealloying is introduced to fabricate a new form of hybrid porous metal with nano-micro double size and regular-random bimodal structure.The Gasar process, also called the metal-gas eutectic directional solidification, that invented by Shapovalov [3] in Ukraine and now in USA some twenty years ago, is used to fabricate porous metals with regularly aligned pores basing on the solubility difference of a gaseous element in solid and liquid metal. Nakajima and his colleagues [4] in Japan studied this process further and called this kind of structure a lotus-type porous metal. They put more attention to various fabrication techniques and properties of lotus-type porous metals. Li heading a group [5-6] in P.R. China studied the mechanism of Gasar process and process controlling techniques. The Gasar pore structure and porosity can be controlled by processing parameters, and a regular Gasar structure with oriented pores distributing uniformly in the solid matrix can be obtained under optimized processing parameters."

Jan 1, 2014

By L. Klinger, T. Werber, LA Levin, A Katsman

"The process of catastrophic carburization known as ""metal dusting"", whereby a solid metallic material is converted into fine particles in a carburizing atmosphere, was analyzed. It was shown that this conversion is the result of plastic deformation and subsequent fracture accompanying diffusional phase formation in the near-surface layer. The process is controlled by internal stresses arising during phase transformation. Competition between stress generation and relaxation may result in the attaining the ultimate strength in the near-surface layer and its fracture. Such a mechanism of metal disintegration may occur in a certain temperature interval depending on the kinetic and geometrical parameters of the system - the diffusivities of the alloy's components, the ratio between specific volumes of the new and the old phases, and the ultimate plastic strain. The temperature interval for disintegration of carbon steel, the rate of disintegration, and the period of the disintegration cycle, were evaluated and compared with experimental data. IntroductionCatastrophic carburization, known as ""metal dusting"", consists in conversion of a solid metallic material into fine particles. The process occurs in a carburizing atmosphere at elevated temperatures. The corrosion product, usually named ""coke"", consists of metallic particles dispersed in a loose carbon matrix. Under industrial conditions metal dusting takes place, for example, in a gas mixture of CO and H2 or in hydrocarbon environments. Steels, nickel- and cobalt alloys are susceptible to this kind of wastage in the temperature range 400-800°.A mechanism of metal dusting in steels was proposed by Hochman [1] and later developed by Grabke and coworkers [2-5]. According to the proposed model, the process consists of the following reaction steps:"

Jan 1, 1996

By Alice Barreto Bevitori, Frederico Muylaert Margem, Renan Sopeletto Carreiro, Sergio Neves Monteiro, Isabela Leão Amaral da Silva

"The ramie fiber is one of the strongest lignocellulosic fibers with applications ranging from simple items such as fabrics and ropes to engineering composites for automobile parts and building panels. Characterization of the ramie fiber has recently been conducted for physical and mechanical properties. In principle, thinner ramie fiber could be comparatively stronger and consequently more effective as a composite reinforcement. In this work an attempt to correlate the ramie fiber elastic modulus obtained in tensile test with its corresponding diameter, precisely measured by means of a profile projector, was carried out. Tensile results analyzed by the Weibul1 statistic showed a significant increase in elastic modulus with decreasing the diameter of ramie fiber. Scanning electron microscopy observation of the fracture of selected ruptured fiber revealed possible mechanisms that could justify the elastic modulus/diameter inverse dependence.IntroductionEngineering applications of natural fibers obtained from cellulose-rich plants, also known as lignocellulosic fibers, are currently being the focus of attention. In fact, they are considered an enviromnental1y correct alternative to substitute synthetic fibers such as the glass fiber, associated with an intensive intake of energy during production, as reinforcement of polymer composites [1-4]. In recent years there has been a growing tendency towards the use of lignocellulosic fiber composites in several industrial sectors from civil constructions to car making. In particular, the automotive industry is expanding the number of both interior and exterior components made of natural fiber composites [5]."

Jan 1, 2012

By Leonard J. Friedman

Modern smelting systems using continuous, flash and/or oxygen smelting processes have a significant effect on the choice of sulfur dioxide control processes and system arrangements. Based on gases from an enriched air or oxygen smelting furnace and copper converters the paper reviews and analyzes alternate processes and system arrangements for recovery of sulfur dioxide. The work indicates the choice system to include a conventional sulfuric acid plant for converter gas and a liquid SO2 plant to handle the high strength smelting fur¬nace gas. The liquid SO2 plant would be used as a fly-wheel to damper the flow and SO2 concentration variations of the con-verter acid plant. Potential energy recovery alternates and product flexibility are also reviewed.

Jan 1, 1983

By Martin J. Hansel, Jan Bäckström

Starting from historic perspectives on converting at the Rönnskär Smelter, the continuous developments of refractory practice is described. In the development the joint efforts of operators and suppliers of refractory have lead to significant achievements. This paper comprises the development of the converting process and the refractory lining as well as future prospects regarding operation and refractory lining design, especially in the face of equipment and raw material availability. 81

Jan 1, 2009

By Gary K. Elliott

Many industrial processes generate hot waste gases which contain particulate pollutants. Conventional clean-up techniques suffer limitations either because collection efficiency is low or because the gas must be cooled before treatment. thereby increasing costs and preventing energy recovery. The application of increasingly stringent environmental legislation to the non-ferrous metallurgical industry is presently illustrating these conventional technology limitations. Low density ceramic media allow filtration to ta,ke place at 'high temperatures and are now rapidly becoming accepted In many industries. This paper reviews experiences with a proprietary low density ceramic filter element. CerafH. It includes consideration of the structure, composition. typical operating and case studies with particular reference to non-ferrous metallurgical furnace applications.

Jan 1, 1992

By Gary K. Elliott

Many industrial processes generate hot waste gases which contain particulate pollutants. Conventional clean-up techniques suffer limitations either because collection efficiency is low or because the gas must be cooled before treatment. thereby increasing costs and preventing energy recovery. The application of increasingly stringent environmental legislation to the non- ferrous metallurgical industry Is presently illustrating these conventional technology limitations. Low density ceramic media allow filtration to take place at high temperatures and are now rapidly becoming accepted in many industries. This paper reviews experiences with a proprietary low density ceramic filter element, Cerafill. It includes consideration of the structure, composition. typical operating and case studies with particular reference to non-ferrous metallurgical furnace applications.

Jan 1, 1992

By W. John Rankin

The finite and non-renewable nature of mineral resources poses unique challenges for sustainability: How can mineral and material needs of society be satisfied indefinitely? How can the benefits of exploitation of minerals best be captured for present and future generations? How can the environmental problems caused by large scale mining and processing best be ameliorated? These issues are rarely addressed, or if so only incidentally, in traditional courses in geology, mining, metallurgy and materials yet addressing them will increasingly be a major role for professionals in the minerals and materials industry and related sectors and agencies. This paper describes a framework for examining these and other sustainability issues related to meeting future material needs from non-renewable resources. The framework may be useful for educational purposes, either as the basis of a dedicated subject or by including the elements of it throughout a traditional course in relevant subjects.

Jan 1, 2014

By Maria D. Salazar-Villalpando, Anthony Cugini, Bryan Reyes

"The electrochemical reduction of CO2 was performed in a laboratory-made, divided Htype cell. A copper electrode was used as the cathode. An Aldrich Nafion 117-type ion exchange membrane (0.18mm thickness) was used as the diaphragm. NaHCO3 and KHCO3 were studied as the catholytes. Hydrogen evolution from water reduction and products from CO2 electrochemical conversion were recorded. Higher CO2 reduction enhancement was observed by KHCO3 as compared to NaHCO3. The main conclusion of this work is that in fact CO2 can be electrochemically reduced with copper electrodes.1.-INTRODUCTIONThe direct electrochemical reduction of CO2 may allow for a simple process and, by avoiding high temperature reactors, would enable the process production rate to be quickly varied to follow the time of day availability of surplus electricity [1]. Temperature has a major effect on the electrochemical conversion of CO2 since its solubility increases when temperature decreases [2]. The electrical potential applied to the electrochemical reacting system will have an influence on the product distribution, as well. For example, a narrow potential range during cyclo-voltagraphic studies will determine the detection of a lower number of products. A recommended potential range to study the electrochemical reduction of CO2 is -2V to 2V. Moreover, the reaction rate on the electrode is governed by various processes, such as the kinetics of electron transfer, adsorption/desorption at the electrode surface, and diffusion of CO2 to the Cu electrode. The availability of active species, CO2 for electro-reduction, is extremely low at the vicinity of the electrode surface and it seriously interferes with the rate of mass transfer. In batch type electrolytic reactors, depletion of CO2 at the surface takes place first. CO2 from the bulk then has to diffuse to the electrode surface, resulting in mass transfer controlled kinetic phenomena. During the above process, several other competitive side reactions could suppress the primary reaction even though the cathode has good electro catalytic properties for reduction of carbon dioxide. When the dynamic supply of specific active species is ensured to electrode surface, the mass transfer effects are minimized to certain extent. Hence it is envisaged that a continuous flow reactor is more efficient for the electro-reduction of CO2 in CO2 saturated aqueous electrolytes. The primary reactions that occur at the copper electrode during the reduction of CO2 are listed below (with the standard potentials calculated using formation energies [1] :"

Jan 1, 2010

By T. Inami

The chlorine leach of the anode slime was studied in order to improve the treatment process at the Niihama Nickel Refinery. The anode slime originates from the nickel matte electrorefining and, contains 3-5% of nickel as sulfides. A comparative study has been conducted on the filter cake resulting from the sulfur filtration of the molten anode slime. The kinetic factors of the chlorine leach such as temperature, grain size were defined. Under the optimized condition, 70-80% of the nickel is recovered from the slime or filter cake. On the basis of these results, the chlorine leach process for the treatment of anode slime has been established. The leaching plant has been installed and successfully operated since 1986.

Jan 1, 1988

By Michael P. Meisel

Solinox is a physical scrubbing process capable of removing a number of noxious materials from off-gasses, especially SO2, hydrocarbons, halo¬gens, heavy metals such as dust, etc. As these materials are dissolved physically, (not chemically bound), the solvent is absolutely stable and no by-products are formed in the scrubbing cycle. The process has been installed in three plants up to now, treating from approximately 30 MMSCFD to approximately 100 MMSCFD. These installations are in a non ferrous metal smelting operation, in a cellulose factory, and in a roasting process.

Jan 1, 1992

By Kandipati Sreenivasarao

Ion flotation is a promising separation process for continuously removing toxic metal ions from dilute process effluents. After treating the effluent with appropriate surfactant(s), the metal- bearing species adsorb onto the surface of rising gas bubbles and can be collected as foams. Suitable collectors have been identified for most of the elements of the periodic table. However, a better understanding of the thermodynamic, kinetic and engineering principles that determine the performance of ion flotation systems would facilitate commercial utilization of this technology. A model system of sodium dodecylsulfate-ethanol has been studied for the removal of Cu (11) from dilute solutions, using laboratory-scale flotation columns. This paper reports the effects of the air flow rate, solution height, foam drainage zone height and col1ector:metal ion ratio on the flotation kinetics, ultimate recovery of metal, flotation product grade, foam losses and effluent quality. Preliminary results for Pb (11) removal are also reported.

Jan 1, 1993