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By G. Achurra

The products of the smelting of copper concentrates in an El Teniente Converter (CT) are a high grade matte, analyzing 74-76% Cu; and a highly oxidized slag, typically containing 15-20% Fe3O4 and 4-10% Cu. The El Teniente Division of CODELCO¬CHILE has developed a slag reduction-cleaning process, that is practised in a tilting, horizontal furnace, to recover copper from these slags. The El Teniente slag cleaning process has been successfully implemented at the El Teniente Caletones smelter and various other smelters in Chile: Today, eight such slag cleaning furnaces, each with a capacity of 800-1000 tonnes/day, are in operation in Chile. This paper discusses basic laboratory research and industrial tests that led to substantial reductions in the slag cleaning cycle time and the specific consumption of fuel and reductants. Simultaneously, the slag cleaning off-gas quality was improved. Based on the experimental results, recommendations were made to improve the practice of the El Teniente slag cleaning process. The recommended modifications have been fully implemented at the Caletones smelter.

Jan 1, 1999

By Jimsher Aneli

The investigation of some peculiarities of conductivity dependence on filler type and amount in the polymer composites has been conducted. It is established, that conductivity of composites based on phenolformaldehide resin essentially depends on proportion of double fillers: graphite + carbon black, graphite+ andesite, contained in composites. It was shown, that these composites characterized by synergetic effect ? non additive influence of fillers concentration on the conductivity of composites. Some other properties of composites contained binary fillers (effect of temperature and pressure on the conductivity) have been investigated.

Jan 1, 2006

By David B. Dreisinger

The total pressure oxidation treatment of arsenical copper ore and concentrate from the El Indio mine of Banick Gold was tested in benchtop autoclave treatment. The concentrate oxidation typically achieved ~95% copper extraction. Copper extraction was limited by the reprecipitation of a complex precipitate containing arsenic. Gold extraction by cyanidation of the oxidation residue was around 95%. Silver extractions were less than 10% due to the formation of argentojarosite in the autoclave. The total pressure oxidation of the whole ore sample was more successful. Copper extractions of 98-99% were routine achieved. Gold extraction by cyanidation was +95%. Silver extraction could be increased to as high as 95% by using the lime boil treatment. A process flowsheet was proposed based on the results achieved. Copper recovery was proposed by direct solvent extraction and electrowinning of copper by treating the dilute solution from the autoclave discharge.

Jan 1, 1999

By Thomas Schuman, Jaan Kers, Lucas N. W. Damoah, Xiangjun Zuo, Lifeng Zhang

"Rapid technological innovation has propelled the use of electronic equipment leading to the generation of more and more waste electrical and electronic equipments (WEEE). Printed wiring board (PWB) is a component made of one or more layers of insulating material with electrical conductors. To investigate an environmentally friendly process to recycle PWBs, PWB samples with and without additives were pyrolyzed. Liquid, gas and solid products were achieved with different conversion fraction. Analysis of the exhaust gases from the experiments using GC-MS and MS showed that without CaCO3 additives poisonous gases such as C6H6 and HBr were produced which were adequately controlled if CaCO3 was added.IntroductionPyrolysis is one of the best methods for treating complex mixtures of waste polymers and to recover the material and energy content. The process consists of thermal decomposition at moderate temperatures in total absence or small amount of oxygen in which the structures of polymers break down into smaller intermediate products "". The decomposition temperature of a substance is the temperature at which the substance breaks up into smaller substances or into its constituent atoms 2). Thermal treatment of PWBs were reported using DC Arc Plasma furnace 3), and fixed bed reactor 4). One drawback in dealing with thermal treatment of PWB scraps is the likely production of super-toxic halogenated dibenzodioxins and dibenzofurans from the bromine containing structures. Pyrolysis of organic materials contained in waste PWBs leads to the formation of gases, oils, and chars which can be used as chemical feedstock or fuels ""'. Dehalogenation of the pyrolysis product of electronic scraps is essential to make it commercially acceptable. It would be obviously the most advantageous solution as pyrolysis and dehalogenation are carried out simultaneously. Reported pyrolysis investigations are at experimental stage and have been carried out in vacuum, molten salt, fluidized bed, rotary kiln, entrained, stationary, and moving bed reactors 7). Comparing to the incineration and combustion of PWBs, the pyrolysis process has several characteristics: 8'"">) 1). Converting the organic solid substance into fuel gas, fuel oil and carbon-black as storage energy; 2) Emitting toxic substances such as sulfur, bromine and heavy metals in wastes; and 3) Keeping metals from being oxidized. Although many researches into the pyrolysis of PWB wastes have been reported, most of the works have been carried out using analytical pyrolysis techniques or very small batch reactors ""~'5). Also, most of the works for the pyrolysis of PWBs haves concentrated on the composition of the organic products, particularly the brominated organics. The current study is to investigate the pyrolysis of PWB powders in a small TG-DTA scale and a 50-gram tube furnace scale."

Jan 1, 2011

By L. Béjar-Gómez

The aim of this research work is to study and characterize the precipitates in structural microalloyed steel by transmission electron microscopy and analysis by low resolution. Microalloyed steel with niobium was produced by casting in an electrical induction oven of 25 Kg capacity. Carbon content in steel was less than 0.1 % and 0.036% of niobium. Steel was processed thermomechanically; reheated to 1250 °C and hot rolled on a laboratory mill to a 13.0 mm thick plate with a finish rolling temperature of 900ºC and a thickness reduction of 80% . This work shows what precipitates are present in steel, the type of precipitates and their morphology. Analysis by transmission electron microscopy of low resolution was applied to obtain the chemical analysis of precipitates and the matrix. Spectroscopy of dispersive energy (STEM - EDS) was applied to obtain the element profile of precipitates. Particles of precipitates of NbC were found; with cubic morphology and size from 70 to 130 nm, circular morphology and size from 10 to 70 nm, polygonal morphology and size from 10 to 80 nm.

Jan 1, 2006

By John L. Uhrie

Oxide stockpile leaching operations can realize increased copper recovery and decreased acid consumption from in-situ generated acid resulting from the oxidation of intentionally introduced pyrite recovered from mill tailings or other sources. While all oxide leach ores can benefit from pyrite addition, low acid consuming ores can show remarkably increased recovery and net acid generation; however, more highly acid consuming ores will show benefit more exclusively through increased copper recovery. Additional work shows that the value of highly acid consuming ores can be optimized by balancing copper recovery against acid consumption.

Jan 1, 1999

By Sergio Bustos

Covellite resulting from an original 0.5 % Cu(tot) chalcocite ore has been leached in columns at different temperatures, in the lower range of 10 - 20 °C, under acid - ferric bacterial leaching conditions. Dissolution of copper from covellite depends on the rate and extent of sulphide oxidation by ferric ion. While it is recognised that the dissolution of sulphide minerals is electrochemical in nature, an apparent chemically controlled dissolution pattern was measured with activation energy of 78.09 kJ/mol (18.66 kcal/mol). Ferric iron is the main oxidant and its production and availability will depend on the bacterial activity developed in the system. This activity is characterised by the population size and by the specific oxidation rate of the bacteria. Bacterial growth was followed directly by the number of bacteria appearing in the column effluent solutions and indirectly by the generation of ferric iron or by the total oxidation observed in the columns. These results have been interpreted by using the heap oxidative capacity parameter, which indicates an equivalent ferric production of about 0.07 - 0.15 kg Fe +3/t/day at 20°C. Although bacterial activity decreases to about 0.03 kg Fe +3/t/day with decreasing temperature, a significant bacterial oxidation is still observed at 10 °C. However, extended lag times are observed, which delay the start of bacterial growth to times concurring with covellite leaching. Under these conditions, bacterial activity is displayed through a population controlled by the rate at which- ferrous iron is released from the reducing covellite surface. These results suggest the potential benefit of including some kind of inoculation when operating at lower temperatures. Also, heat loss control and/or heat addition to the heaps should be considered during process design and operation of ferric bacterial heap leaching of secondary copper sulphide ores at temperatures lower than 20°C.

Jan 1, 1999

By Kenji Monden

"The creep properties of tin-based lead-free solders Sn3.0AgO.5Cu and SnO.7CuO.1Ni and lead solders 10Sn90Pb and 50Sn50Pb were investigated at temperatures between 298 K and 398 K. The creep-rupture time decreases with increasing initial stress and temperature. The analysis of the solder creep curves uses the Omega method. The creep rate E is expressed by following formula: 1n ? = 1n ?0 + O?, where ?0 and O are experimentally determined. The parameter Eo increases with increasing initial stress and temperature. The activation energy for ?0 is 108 kJ/mol for Sn3.0Ag0.5Cu and 85 kJ/mol for SnO.7CuO.INi. These energies suggest that the lattice diffusion of tin is dominant. The energy of 1OSn90Pb is 37 kJ/mol and that of 50Sn50Pb is 67 kJ/mol. The creep-rupture time is calculated using the parameters, ?0 and O. The calculated creep-rupture time is in good agreement with the measured creep-rupture time.IntroductionLead-free solders are replacing traditional tin-lead solders as part of a major trend toward protecting the earth's environment. However, tin-lead solders are currently needed for a high temperature range. Since creep is the main deformation mechanism in solder joints, understanding a constitutive model for creep and examining creep data for solders are important for reliability analysis of solder joints. A steady-state creep equation is generally used for solders [1,2], and it supposes that the secondary-, or minimum-, creep rate occupies the entire creep life. However, secondary creep accounts for only about 15 % to 40 % of the entire creep life for solders. Thus, the equation may not represent the entire creep life."

Jan 1, 2012

By O. C. Rojas

Improvements and modifications on lay out and process, from 1997 till 1998, are presented. Based on a Teniente Converter, started up 1993, a Strategic Development Plan was structured to increase the production efficiency and comply with the enviromental regulations, too. It considered the oxygen supplies to the Teniente Converter and Peirce Smith converters; reverberatory furnace shut down as a smelting unit; and the Teniente converter slag treatment through a combined process between a Slag Settler furnace and flotation. Also it included the off-gas handling and treatment.

Jan 1, 1999

By José C. Escobedo B.

A kinetic study of nitrogen dissolution in a. electromagnetically stirred Co-Cr-Mo alloy bath was made. The experiments were carried out at 1693, 1723 and 1743K of temperature, with a nitrogen pressure of 0.67 atm. The mass transfer coefficients were obtained, finding that their values increase as temperature grows. The true kinetic constants were calculated. It was found that at 1693K of temperature, the kinetics of the nitrogen dissolution process is controlled by a mixed mechanism involving both transport processes and chemical reaction, while at 1723 and 1743K of temperature, the kinetics is controlled only by transport processes mechanisms.

Jan 1, 1995

By C. K. Gupta

The paper reports on the experimental work and results obtained in processing a xenotime concentrate. The rare earth resource concentrate has been treated by three different methods namely, hydrothermal leaching, alkali roasting and alkali pugging or baking. The recovery in hydrothermal leaching with caustic soda at 150-160°C has been 89%. En comparison, processes involving alkali roastings with soda ash at 850°C and with caustic soda at 500°C, and alkali pugging or baking with caustic soda at 200°C have given recovery values close to 100%

Jan 1, 1992

By H. U. R. Kattentidt, W. L. Dalmijn, T. P. R. de Jong

Sensor controlled sorting is a promising technique for the upgrading of scrap aluminium alloys. In a universal detection system of Delft University characteristic features are extracted · from the material particles by means of cameras. Examples are size, texture, edge-structure, homogeneity, and colour pattern. Additional sensors are added for higher selectivity: electromagnetic detection, light transmission, spectral reflection and more. Signal processing theory learns that a classification of particles fundamentally improves as the number of independent features increases. At the laboratories of the Delft University a test bench is available for the development of advanced multi-sensor quality control and sorting systems. It is based on a software system for detection, segmentation and classification of particles, which was especially developed for this application. Work is now in progress for high-speed detection and sorting of non-ferrous alloys, including aluminium casting and wrought alloys. A recently developed actuator design enables positive sorting into more than 3 fractions of particles that are randomly orientated on a flat conveyor belt.

Jan 1, 2000

By Katsunori Yamaguchi

The zinc, lead and alumina contents in copper smelting slag are increasing with the increase in waste recycling. The recovery of base metals such as lead and zinc from copper converter slag is important from both an economical and environmental perspective. As a fundamental study of the metal recovery by reduction process, activity coefficients of ZnO and PbO in the CaO-SiO2-FeOx-5mass%AlO1.5 slag under iron saturation at 1573K are derived from the data of slag-metal equilibrium experiments. On the basis of the obtained data, the activity coefficients of ZnO and PbO in the CaO-SiO2-FeOx-5mass%AlO1.5 slag were compared with those of the CaO-SiO2-FeOx ternary system. Addition of alumina increases activities coefficient of ZnO and PbO in SiO2 rich side of the slag, and decreases them in CaO rich side.

Jan 1, 2006

By Henry Salomon-De-Friedberg

Quebrada Blanca has had to overcome numerous challenges in achieving design throughput. The paper reviews how actual practice has evolved from the original design. The major challenges that were encountered from heap leaching to solvent extraction, the tankfarm and through to electro winning are discussed. The eventual solutions to some of the key issues are presented.

Jan 1, 1999

A rotating-discelectrode system was used to evaluate the electrochemical behaviour of Eu(III) during its reduction in NaCl solutions. The solution pH and NaCl concentration have a great effect on the reduction kinetics. The thermodynamic modelling study also revealed that Eu(III) exists in various forms in NaCl solutions. At a low concentration of NaCl, the predominant species is the free Eu3+. Other Eu-chloro complexes become more predominant when the NaCl concentration increases.

Jan 1, 1992

By M. Arenas

A corrosion study of a bonded NdFeB permanent magnet materials alloyed with titanium carbide additions has been undertaken. The materials were produced by rapid solidification by melt spinning. Commercial epoxy was used as a bonding medium. The corrosion results were compared with those of a near stoichometric unalloyed NdFeB. Anodic polarization and potentiostatic techniques in 0.9 M Na2SO4 solutions were used to characterize corrosion behavior. It was found that the addition of 6 a10 Tic resulted in superior corrosion resistance, as indicated by lower corrosion currents and less iron dissolution at fixed potential.

Jan 1, 1997

By Joseph J. Poveromo

Technical progress in ironmaking will be discussed in three sectors: blast furnace ironmaking, direct reduction and alternative ironmaking to feed electric arc furnaces and ironmaking for waste oxide processing. The contributions of iron ore producer, Quebec Cartier Mining, in each sector will be outlined.

Jan 1, 2006

By Wenshan Zhang

The industrial production experiments on Zn, Mn simultaneous leaching, impurity removal and ZnMnO2 simultaneous electrolysis were carried out. The process flow, technical requirement and research results about the experiments were discussed and the good technical quail-fixation and high quality of products were obtained. Reactions for each major technological process have been expatiated based on the thermodynamic analysis.

Jan 1, 2006

By Etsuro Shibata

For the treatment of huge amounts of the sulfur which is from the earth by both natural and man-made activities, a harmonized sulfur cycle was presented. The man-made sulfur cycle which includes sulfur circulation from oil, coal and ore was analyzed in detail based on the recent world sulfur trend. Then the man-made cycle was compared with the natural sulfur evolution such as volcano. Finally, the harmony in both natural and man-made sulfur cycles was discussed.

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