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By Robert W. Bartlett

Chalcopyrite in copper flotation concentrates can be hydrothermally converted to digenite with oxygen in a continuous process, with rapid kinetics when operated above 200°C. This eliminates large amounts of sulfur and iron. These "super-concentrates" have potential for debottlenecking smelters and avoiding capital intensive future smelter expansions, otherwise required in the late 1990s. The technology of producing super- concentrates is described, with cost estimates, and the use of super-concentrates as smelter feed is discussed, with examples.

Jan 1, 1992

By Albert W. Spitz

Profitably recovering copper and precious metals from copper bearing scrap is a demanding and frustrating combination of art, science and economics. With fluctuating markets, varying raw materials and increasingly stringent environmental regulations requiring process revisions, practically everything is changing. The volatile copper market constantly shifts the percentage of copper in the scrap that can be economically processed. Scrap that has value one day may incur a disposal cost the following day. Also with less copper in the scrap, more residuals, slag, fume, etc. are generated which frequently present disposal problems and infrequently generate income. The ever increasing amounts of electronic scrap add value to the copper produced by virtue of the precious metals present. Printed circuit board materials create more slag and organic off gases which must be treated. Finally, the emphasis on reducing emissions of organics and other metals, especially lead, is a continuing challenge. Stack gases, fugitive emissions and ambient air quality all demand constant surveillance.

Jan 1, 1997

By I. Gaballah

Spent hydrorefining catalysts may contain 4 to 6 % of COO and/or NiO, 8 to 16 % of Moo3 and up to 10 % V205 generally supported by alumina. Raw samples are roasted in order to eliminate carbon, sulfur and hydrocarbons contained in the spent catalysts. The roasting optimum temperature and time are 500 "C and 7 hours. Selective chlorination of roasted samples with Cl2 + air, Cl2 + N2 and Cl2 + CO is investigated in order to recover the valuable metals. Depending on the chlorination it is possible to recover more than 80 % of the Ni and Co about 95 % of the Mo and up to 80 % of vanadium compounds. Cobalt and nickel chlorides are obtained by leaching the chlorination residues' by acidified water. Molybdenum and vanadium chlorides and/or oxychlorides are obtained by selective condensation from the vapor phase. The chlorination of the catalyst support, Al2O3, can be limited to less than about 5 %. Besides the reaction temperature and time, the oxygen partial pressure of the chlorinating gas mixture appears to be the key factor for the reactions' selectivity.

Jan 1, 1993

By Tuula Mäkinen

In 1959 Outokumpu started up an integrated nickel smelter and refinery at Harjavalta. The flash smelting ? Peirce-Smith converting route was applied, and the high-grade converter matte was further refined to nickel cathodes by leaching and electrowinning. In 1995 the production capacity was increased from 17 000 mtpa to 52 000 mtpa, based on the Direct Outokumpu Nickel Smelting Process. The additional refinery capacity is based on hydrogen pressure reduction, producing nickel powder and briquettes. The smelting operation is currently part of Boliden Group and the nickel refinery part of OM Group. In the DON technology, high-grade nickel matte with low iron content is produced in the flash smelting furnace directly without subsequent converting. The metal values in the smelting slag are recovered in an electric furnace as an iron containing Ni-matte. The mattes produced differ from the conventional nickel mattes in many respects, and therefore focused R&D efforts have been made in order to cope with their melting points, fluidities and settling properties. When developing and operating metallurgical processes it is crucial to manage and control the characteristics of the products as well as by-products generated in different steps of the process chain. The low melting points of the high-grade nickel mattes produced in the DON furnace, particularly those low in copper, have pointed out challenges in the furnace design, in particular in the hearth and its thermal engineering. Also key issues of the DON technology are smelting of high-magnesia concentrates, the recoveries of nickel and copper, as well as those of PGM`s and cobalt. These factors can be affected by a proper selection of the process concept, and the operational conditions in the processing vessels. This paper deals with the experience of the DON technology gained over the first ten years of operation, including the significant environmental impacts. Selected results of the thermo-dynamic modelling of DON and EF mattes and high-magnesia slags are reviewed, with the reference to the mattes produced. Also the design principles of the FSF and EF will be discussed.

Jan 1, 2006

By Shadia J. Ikhmayies

CdSxTe1-x and CdS1-yTey solid solutions are usually formed in the interfacial region in the CdS/CdT thin film solar cells during the deposition of the CdTe layer and/or the processing steps of the device. It is well known that CdCl2 heat treatment encourages the formation of the CdSxTe1-x alloy which improves the solar cell performance. In this work, indium doped CdS1- yTey thin films are produced by first producing CdS:In thin films by the spray pyrolysis (SP) technique on glass substrates, then annealing the films in nitrogen atmosphere in the presence of elemental tellurium. The films are characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmittance measurements. The transmittance is used to deduce the optical parameters such as; the extinction coefficient, refractive index, besides to the real and imaginary parts of the dielectric constant. The dispersion parameters such as Eo (single-oscillator energy) and Ed (dispersive energy) of the deposited films are also estimated and discussed.

Jan 1, 2015

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 Cameron Harris

With the consolidation of the copper industry in the second half of the 20th century resulting in fewer plants treating ever increasing quantities and qualities of feed, the enormous flexibility of the Noranda Process gives it significant advantages over many competing technologies for the production of matte. Toll smelting, recycling, and secondaries treatment will become the cornerstone of profitable operations for all but the lucky few who have large captive mines associated with the smelter. Consequently, the ability to respond to changing market conditions without significant metallurgical or operational upsets will be of considerable commercial advantage. The inherent stability of this bath-smelting process leads to tight matte grade control, while the bath turbulence leads to rapid consumption of feeds with widely varying physical characteristics. Low capital and operating costs combined with a layout suitable for retrofit into existing converter aisles makes it a sensible choice for parts of the world still experiencing the aforementioned consolidation, which is essentially complete in fully developed economies such as the United States of America and the European Union. This paper will discuss features of the Noranda process compared with other technologies and its place in the future global copper production industry, which is set to become increasingly competitive and aggressive.

Jan 1, 2002

By B. R. Westphal

The Integral Fast Reactor (IFR) concept being developed by Argonne National Laboratory is based on the pyrometallurgical processing of spent nuclear metallic fuel with subsequent fabrication into new reactor fuel by an injection casting process. During fabrication, a dilute scrap stream containing uranium alloy fines and broken quartz (Vycor) molds is produced. Waste characterization of this stream, developed by using present operating data and chemical analysis, was used to evaluate different uranium recovery methods and possible process variations for the return of the recovered metal. Two methods, comminution with size separation and electrostatic separation, have been tested and can successfully recover over 94% of the metal. Recycling the recovered metal to the injection casting process was evaluated for the different economic and process impacts. The physical waste parameters and the important separation process variables are discussed relative to their effects on the viability of recycling the material. A discussion of the criteria that is being used to establish the acceptable operating limits is also presented.

Jan 1, 1992

By P. Hanniala

In the day-to-day life the copper business of today is influenced directly by the ever-increasing general concern about the environment. In addition to that the inherent shortcomings of the copper smelting business, have since many years been the falling real price level of the metals and the relatively high initial capital investments required for the production units. These shortcomings have been compensated for by high productivity, low specific operating costs, low metal inventory and unbeatable technological superiority. Thus today more than 50 % of the world primary copper is today produced by utilizing Outokumpu Flash Smelting Technology. This figure is expected to grow at an increasing speed in the near future. Characteristic for the Outokumpu Flash Smelting technology is high flexibility for a wide grade of concentrates and the highest sulfur capture owing to at the same time competitive investment and operational costs. The Flash Converting technology offers new options for copper production and optimization of the mine- concentrator-smelter production chain. In the following years it is expected that the trend in copper making is that higher grade concentrates are produced at the mines. Thus increasing amount of high grade concentrate will be available for direct-to- blister Flash Smelting causing an overall cost reduction in copper smelting i.e. both in capital and operational costs. In the '90s new technologies based on Outokumpu Flash Smelting technology have been taken into operation, thus eliminating the non-continuous Peirce-Smith converting process step. New innovative solutions have been used in the latest projects, as in Kennecott Utah Copper, where the new Kennecott-Outokumpu Flash Converting process was started up in 1995. Also, in 1995 the new DON process was started at Outokumpu Harjavalta nickel smelter followed by the Fortaleza nickel smelter in Brazil in 1997. The aim of the continuous development work at Outokumpu has been the expansion of the direct-to-blister process towards lower grade concentrates. The most recent example of this is the start-up at the Olympic Dam smelter in Australia, where the existing direct-to-blister Flash Smelting furnace was replaced with a new one having a capacity of 200 000 t blister copper per annum in just one smelting step.

Jan 1, 1999

By Junji Shibata

Heavier rare earth, which is contained in a small amount in ores such as bastnesite and monazite, has been accumulated as a heavier rare earth residue without doing separation and purification due to the lack of suitable methods. The heavier rare earth residue includes seven rare earth elements such as Tb, Dy, Ho, Y, Er, Tm and Yb. Separation and recovery process of Dy, Y, Tm and Yb from leached solution of the heavier rare earth residue was investigated by using a column method with solvent impregnated resin. The solvent impregnated resin was prepared by impregnation of organophosphorous extractant whose trade name is PC-88A into a macro porous resin, Amberlite XAD-7. It was almost impossible to separate them in simple adosorption and elution steps. However, we attained to individually separate Dy, Y, Tm and Yb from the leached solution first by changing eluent concentration gradually from pH2 to 0.02kmol/m3 HC1 in the elution step, and secondly by using a development column and changing eluerit concentration in the elution step. The separation process flow was proposed for a heavier rare earth residue by using the solvent impregnated resin method.

Jan 1, 1998

By Patricio Ruz, Gabriel Riveros, Carolina Ramirez, Andrzej Warczok, Rober Treimer

"Continuous converting of copper matte produces slag with high cuprous oxide content. The corrosion of chrome-magnesite refractories with slag of high cuprous oxide content is a major problem. Properties of olivine type of slag make the slag very attractive for matte smelting and converting.Analysis of phenomena determining the slag infiltration into the porosity of a refractory and dissolution of refractory components in the slag allowed for better understanding of the mechanisms of refractory destruction.The results of laboratory scale tests of the olivine slag infiltration into open porosity and corrosion showed dominating effects of slag temperature and cuprous oxide content. The optical and X-ray examination of slag samples permitted the definition of the mechanism of formation of new phases and refractory deterioration. 71"

Jan 1, 2009

By Varuzan Kevorkijan

A new method for faster production of functionally graded metal-ceramic laminates is based on reactive pressureless counterflow infiltration/penetration of a ceramic substrate with two different metallic infiltrants. The porous or dense ceramic preform is pressurelessly infiltrated or penetrated from one side by the first metallic infiltrant to the desired cross section of the preform, producing the top layer made up of the solidified infiltrant and the underlayer consisting of reactive infiltrated preform. The partly infiltrated perform is then completely infiltrated starting from the other side by the second metallic infiltrant, in this way fabricating the internal layer, consisting of the ceramic perform infiltrated with the second infiltrant and the bottom layer formed by the solidified second infiltrant. Systems already investigated include carbide, nitride and boride ceramic performs infiltrated with aluminum and magnesium alloys.

Jan 1, 2003

By Varuzan Kevorkijan

A new method for faster production of functionally graded metal-ceramic laminates is based on reactive pressureless counterflow infiltration/penetration of a ceramic substrate with two different metallic infiltrants. The porous or dense ceramic preform is pressurelessly infiltrated or penetrated from one side by the first metallic infiltrant to the desired cross section of the preform, producing the top layer made up of the solidified infiltrant and the underlayer consisting of reactive infiltrated preform. The partly infiltrated preform is then completely infiltrated starting from the other side by the second metallic infiltrant, in this way fabricating the internal layer, consisting of the ceramic preform infiltrated with the second infiltrant and the bottom layer formed by the solidified second infiltrant. Systems already investigated include carbide, nitride and boride ceramic performs infiltrated with aluminum and magnesium alloys.

Jan 1, 2003

By Michael J. Nicol

This paper summarizes some of the results of a study of the reactions involved in the Caron leaching process and identifies the roles of the major dissolved species in the kinetics of dissolution of iron alloy particles formed during reductive roasting. Using rotating disk electrodes and synthetic leach solutions, the reduction of water with the evolution of hydrogen was found not to occur on a dissolving iron surface under typical leach conditions. It has been established that the oxidative dissolution is governed primarily by a reaction involving reduction of Co(III) to Co(II) ions. The reduction of oxygen was also found to make a significant but largely indirect contribution to the kinetics of the dissolution process. The dissolution rates of various iron-nickel-cobalt-copper alloys which simulate the dissolving alloy particles in a Caron plant were measured in synthetic leach solutions under aerobic and anaerobic conditions. The initial dissolution rates of iron, nickel and the iron alloys were found to increase in the presence of thiosulphate, whereas the thiosulphate had a negative effect on the dissolution rates of cobalt and copper. It is shown that the eventual passivation of the iron occurs sooner in solutions rich in Co(II) ions. Whilst these conditions are present in the quench slurry, on-site measurements have shown that due to the very high concentration of reduced dissolved species, passivation does not occur until the slurry is strongly aerated. In the light of these fundamental findings, options for optimizing the rate of dissolution and minimizing the extent of passivation of the iron and iron alloys are discussed. Keywords: Ammonia, leaching, alloy, kinetics, passivation.

Jan 1, 2004

By Joachim Ulrich

The spreading and splashing behaviour of single tin, lead, copper, aluminium and steel droplets impacting on a solid surface were experimentally examined. The droplet impact was observed using a high speed video imaging technique. The onset of splashing and the mass of the secondary droplets of impacting tin and lead droplets was quantified by the weight difference of the droplets before melting and the splat after the impact. The spread factor and the mass of the secondary droplets in dependence of the impact velocity is shown for different droplet materials, initial droplet diameters, target temperatures in ambient air and inert gas atmosphere. An empirical found correlation predicting the transition from spreading to splashing is presented by means of dimensionless numbers.

Jan 1, 1999

By T. T. Lin, N. H. Madsen, K. Groom, B. A. Chin

"The objective of this research is to investigate the feasibility of using infrared sensors to monitor the welding process. Data were gathered using an infrared camera which was trained on the molten metal pool during the welding operation. Several types of process perturbations which result in weld defects were then intentionally induced and the resulting thermal images monitored. Gas tungsten arc using AC and DC currents and gas metal arc welding processes were investigated using steel, aluminum and stainless steel plate materials. The thermal images obtained in the three materials and different welding processes revealed nearly identical patterns for the same induced process perturbation. Based upon these results, infrared thermography is a method which may be very applicable to automation of the welding process.IntroductionAutomatic welding is commonplace in industry today. However, most, if not all, involves preprogramming for performance of a repetitive task. These systems are incapable of correcting for perturbations which arise during the welding process. Control of the welding process requires the identification and monitoring of perturbations in a wide variety of parameters. The varied nature of these parameters and the large number of variables involved have thwarted previous attempts at closed loop control of the welding process. The sensor(s) employed by a control system need to meet rather strenuous requirements. First and foremost of these is that such a sensor must be able to identify and discriminate between perturbations that might affect the quality of the weld, including such geometrical perturbations as a change of direction in the seam between the parts being welded, gaps in the seam or a misalignment of the parts being welded. The sensor should also be able to locate and identify contaminants and impurities in the weld puddle and ahead of it while monitoring the extent of the heat-affected zone and the cooling rate of the metal. The sensor(s) should, additionally, be able to perform these tasks in a time frame that is consistent with automatic control of the welding process. This paper presents results that could aid in the assembly of such a controlled welding system."

Jan 1, 1986

By Rainer Schmid-Fetzer

"Isothermal solidification can be used to form strong bonds at low temperature which remain solid at much higher temperatures. The exploitation of this principally known technique for new high temperature processing steps and applications in electronic assemblies is the aim of this study. Three basically different variants of this bonding process are given. A comprehensive metallurgical screening is performed and the feasibility of binary material systems is given on a quantitative scale. Very attractive systems are spotted that have never been studied before. Detailed examples for the realization of bonding with complex ternary and multilayer systems are given. A highly innovative example is the chip stack or wafer to wafer bonding of unmetallized Si or SiC at 250°C. The proposed bond remains stable above the melting point of Si and enables entirely new semiconductor manufacturing steps. An improved die bonding process was proposed and verified experimentally.1. IntroductionIsothermal solidification can be applied to form strong bonds at relatively low temperature which remain solid at higher temperatures. The general principle of this type of joining processes is illustrated in Fig. 1. An interlayer of a low melting component, Lo, is provided as a foil or a thin film coating between the high melting joint components, Hi. The assembly is heated under moderate pressure to the bonding temperature, T 8 , and a liquid filler forms, either because the melting point of Lo is exceeded or due to a eutectic reaction between Lo and Hi. This molten filler initiates a rapid interdiffusion or reaction diffusion between Lo and Hi and the subsequent approach to an equilibrium state results in isothermal solidification. The solid phases formed at T 8 in the joint region exhibit a remelt temperature above T8 •"

Jan 1, 1996

By J. W. Lyman

The U.S. Department of the Interior, Bureau of Mines, investigated methods to recover valuable rare-earth materials from NdFeB magnet scrap. Although several processing techniques were evaluated" the best separation of rare earths from the NdFeB magnet ,scrap was obtained by sulfuric acid dissolution followed by precipitation of recyclable rare-earth salts. Both sodium and ammonium intermediate double-salt precipitates' that can be converted to a variety of useful neodymium products were investigated. The sodium system showed a neodymium recovery of 98 pct, while the ammonium system yielded 70 pct during double-salt precipitation. The iron-rich effluent following the rare-earth recovery was treated to produce sodium and ammonium iron jarosites that can be disposed of or converted to hematite. By following this new procedure, many materials handling and economic disadvantages found with fluoride or oxalate direct precipitation were avoided.

Jan 1, 1992

By Juan Ruiz-Ornelas, Yousef Mohassab, Ricardo Morales-Estrella, Hong Yong Sohn, Noemi Ortiz-Lara

The effect of mechanical activation on the reduction kinetics of magnetite concentrate by hydrogen was studied. The magnetite concentrate was milled for 8 h using a planetary mill. After the milling process, the average particle size was reduced from 14 to 4.4 m resulting in a lattice microstrain of 0.30. Thermogravimetric experiments were conducted to focus on the chemical reaction as the rate controlling factor by eliminating external mass transfer effects and using a thin layer of particles to remove interstitial diffusion resistance. The onset temperature of reduction was decreased due to the mechanical activation, and the degree of conversion was decreased by sintering of particles which was confirmed by SEM analyses. In view of the results, a reaction rate expression is discussed from which the activation energy is calculated.

Jan 1, 2016

By Vinicius Alves Gomes, Jean Igor Margem, Frederico Muylaert Margem, Sergio Neves Monteiro, Marina Rangel Margem

The interface between the matrix and the reinforcing fiber plays an important role in the efficiency by which an applied load is transmitted through the composite structure. The shear stress at the fiber/matrix interface can be associated with this load transference and, consequently, affects the composite strength. In the present work, pullout tests were used to evaluate the interfacial shear stress of malva fiber in epoxy matrix composites. A small critical length was found for the malva fiber embedded in epoxy, which corresponds to a relatively weak fiber/matrix bond and lower interfacial strength.

Jan 1, 2015