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By María Guadalupe Sánchez-Loredo

Silver from nitrate aqueous solutions was extracted by commercial organophosphorous extractants (tri-n-butylphosphate, Cyanex 471x, Cyanex 301 and Cyanex 302). Quantitative silver extraction was obtained using the Cyanex reagents. After loading, aqueous solutions of several reducing reagents were used to prepare fine silver powders by reductive stripping. Only both extractants Cyanex 471x and tri-n-butylphosphate (TBP) could be reductive stripped and regenerated by aqueous solutions of ascorbic acid, and Cyanex 471x was decomposed to the corresponding phosphine oxide by using sodium borohydride as reducing agent. Silver was recovered as fine particles, which were characterised by means of scanning electron microscopy (SEM). Micrographs showed that the powder size and morphology were directly affected by the composition of the applied organic phases and aqueous reducing media.

Jan 1, 2003

By V. A. Bryukvin

A hydroelectrochemical technology has been proposed and experimentally proven for processing metallic gold- and silver-containing concentrates on the basis of copper and copper alloys obtained as a result of preliminary physico-mechanical upgrading of electronic scrap. The proposed technology is based on hydroelectrochemical leaching of scrap using reversible electric current and diluted nitric acid solutions, containing complexing agents, permitting complete separation of gold from the nonferrous matrix without involving gold in the process, and dissolving copper, zinc, lead and tin virtually without any emission of nitrose gases.

Jan 1, 2006

By K. H. Ho

This paper describes a simplified numerical model which is used to study the skull formation of liquid metal on a rapidly rotating disc in centrifugal atomisation. The skull formation is one of the problems limiting the wide use of centrifugal atomisation. The enlarging skull on the atomising disc reduces the yield of metal powder produced and produces a resistance to the centrifugal force which worsens the quality of the powder. It is costly and often difficult to study the flow behaviour by experiments due to the complex heat transfer and phase transformation during the processing. Computer modelling is therefore a powerful tool for mechanistic understanding of centrifugal atomisation. This paper investigates the flow pattern of the melt on the rotating disc as a function of initial temperature, melt flow rate and disc rotation speed as well as the physical properties of the melt, such as density, surface tension and viscosity using the commercial package Flow-3D. Keywords: Solidification, Rotating disk, Centrifugal Atomization

Jan 1, 2003

By Denis Legault, Ghyslain Dube, Ronald Morin, Jacques Bonneau, Daniel Guay, Keith Annett, Raymond Breault

"·The total recycling of all the constituents present in aluminum dross is now an industrial reality for Akan. This is made possible by the combination of two patented processes: the Alcan plasma dross treatment process, operating since 1990 at its Guillaume-Tremblay Works, and the calcium aluminate fabrication process, operating at AlumiCa's new plant in Thetford Mines. The latter process uses the total non-metallic content of the dross, thus rendering possible the complete recycling of aluminum dross.After describing the plasma dross treatment process, this paper will present the calcium aluminate fabrication process and how both processes contribute to close the recycling loop. The characteristics of Nova!™ by-product will also be described, as well as how they contribute to make a calcium aluminate with chemical and physical properties that are highly sought after. This calcium aluminate, produced by AlumiCa, is marketed under the trade name Kwikflux®. AlumiCa's total production is presently sold to a number of steel plants worldwide."

Jan 1, 2000

By Milind Deo, Neale R. Neelameggham

The mixture of carbon dioxide and water vapor - called Soda [as in carbonated water] can be converted to easily stored transportation fuels. Earlier papers on Soda- fuel metallurgy noted that this conversion is endothermic requiring energy. Reduced state metallic elements - preferably the alkali, alkaline earth elements, or aluminum can act as oxygen carriers. Availability of such a combination in commonly land fille waste materials is shown. Plant based wastes which are normally composted form a better-controlled reagent. The energy required for the reaction can come from solar energy. This paper describes possible reactor designs, which can accommodate this conversion effectively using carbon dioxide recovered from flue gases.

Jan 1, 2008

By Gregor Mori

Niobium electrolysis has been performed in a NaCl-KCl-NaF-NbCls electrolyte. By means of electrolytic .refining the average valency of the niobium ions was determined as well as the crystallization behaviour. In electrowinning runs the influence of the main parameters such as temperature, RF (mole ratio F/Nb), chemical prereduction, niobium content of the melt and current density has been determined with respect to low specific energy consumption and high purity of the deposit.

Jan 1, 1995

By K. D. Peaslee

The 150 metal producers in Missouri generate approximately 8,000 tons of spent refractories each year, most of which is landfilled. Spent refractory samples were characterized and recycling / reuse techniques developed for some of the largest waste streams. Products using recycled materials are compared with products made from virgin materials.

Jan 1, 2000

By L. Dornelles, M. H. Prediger, R. de C. de S. Schneider, D. A. R. Lopez

In this work it was evaluated the environmental impact of sunflower plantation for biodiesel production. It was considered, for life cycle analysis (LCA) of sunflower in familiar agriculture in the South of Brazil, data collected in 23 experimental farmings with sowing in the period from August to November (2006 -2007). The LCA has considered the plantation conditions, energetic efficiency, man power, diesel volume, type of machines, fertilizers and pesticides used. From the analysis carried through it was evidenced that the sunflower produced in small scale does not need the use of tractors to have an excellent productivity and low impact. Therefore, the sunflower can be cultivated, with the necessary cares, in periods that do not compromise the man power for other cultures and the sunflower is an alternative so that the familiar property can produce biodiesel.

Jan 1, 2008

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By Patrick F. Mahoney

Each year in the United States over 10 million tons of metal are discarded with our municipal waste. This, includes, not only ferrous metals, aluminum and copper but gold, silver, platinum and every other precious metal. Resource recovery, as an approach to waste management, is replacing disposal and it presents great opportunities for those in the metal refining and recovery industry. Combustion of waste enriches the metal fraction left in the ash to the point where metals can be efficiently recovered. The recovery and quality of metals can be enhanced by good combustion control. Innovative technology is needed to efficiently tap this generous, and renewable mine.

Jan 1, 1995

By Kent D. Peaslee, Lifeng Zhang, Edith Martinez, Yufeng Wang

The current study investigated the multiphase fluid flow, heat transfer, solidification of the steel, and the motion and entrapment of inclusions during the centrifugal casting process using FLUENT software. User-defined functions (UDFs) were developed to add velocity with a value related to the rotation speed and radial distance to the solidified steel, to exert a centrifugal force to the motion of inclusions, and to add the entrapment condition of inclusions at the solidifying shell and export the entrapment locations of the inclusion. The calculation shows that there are two peaks of inclusions along the thickness of the produced tube: one at close to outer surface and another one close to the inner surface of the tube. With a larger rotation speed, inclusions tend to be entrapped more towards the inner surface. The calculation agrees well with the industrial measurements.

Jan 1, 2012

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By Levent Özmen

Colemanite is a mineral containing varying amount of boron that is found in abundance in Turkey. It has a good possibility to be used as a flux in iron and steel industry. In this study a review of the use of colemanite, as a flux agent in steel production has been carried out and various related aspects such as its influence in metal-slag reactions, solubility of lime and magnesia in the slag are discussed along its performance in several points of views including its technical and environmental usage characteristics. Positive and negative factors of using this material as a flux are also underlined.

Jan 1, 2006

By Y. Prévost

The Noranda Continuous Converting Process was commissioned in November 1997 at the Home smelter in Rouyn-Noranda, Quebec, Canada. It has completed over 18 months of successful operation. Excellent team work and technical expertise contributed to achieve targeted production levels and environmental goals after only a few months of operation. The operating results have demonstrated the flexibility of the process in producing blister copper from a variety of copper feed materials including a combination of molten and solid copper matte, reverts and fluxes. This paper describes the startup activities and process optimization tasks performed during the first year of operation of the new Noranda Converter.

Jan 1, 1999

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By M. -L. Metsärinta, J. Nyberg, A. Roine

The Kokkola roasting plant uses more than 20 different zinc concentrates every year. During recent years there has been an increase in the variation in concentrate quality; in particular, the amount of fine-grained and low-grade concentrates has increased. Therefore, a great deal of development work has been carried out to improve the operational flexibility, online availability, production capacity and calcine quality of the roasting plant. This work consisted of a heat and material balance model of the roasting based on HSC Chemistry software, a new water admixture system for the concentrate feed, a new oxygen feed system for the process air line, improved cooling of the furnace and boiler and improved operational practices, dust removal and concentrate mixing. These new process control tools and other improvements, as well as some test results, will be described in this paper. The oxygen feed may be used to improve production capacity and to decrease the sulfide content of the calcine. The water feed may be used with fine concentrates to decrease both dust carry-over and the temperature in the top part of the furnace. Improved cooling of the furnace and boiler helps to increase production capacity.

Jan 1, 2000

By Nathaniel Arbiter

The first ammonia leaching plants, applied to copper carbonate and native copper tailings in 19 15, were followed more recently by research and development of flowsheets for ammonia leaching of sulfide concentrates. These were applied to two commercial plants. Anaconda's Arbiter Plant started up in 1974 with a design capacity of 36,000 tons/year of cathodes, to be produced by ammonia leaching with oxygen, followed by solvent extraction and electrowinning. The plant shutdown in late 1977 as a result of high maintenance and operating costs, partly due to harsh winters; to complications associated with sulfate disposal; and to changes in mineralogy. BHP's Coloso plant in Chile was designed to produce 80,000 tons/year of cathodes by leaching part of Escondida's concentrate production. Using a similar flowsheet but with air and low temperatures to avoid sulfate production, it started up in late 1994 and shutdown in mid-1998, after failing to reach cathode design capacity, and experiencing problems with its technology. The paper reviews the technologies and also alternative methods for overcoming the problems.

Jan 1, 1999