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By Baozhong Zhao

The direct smelting of copper concentrates to copper metal in a single furnace offers environmental and energy advantages over conventional two-stage copper smelting processes. However, the direct copper making results in unacceptably high level impurities (As, Sb and Bi) in the anode copper. Experimental studies have shown that it is possible to remove these impurities from molten copper by injection of sulfur-hexafluoride. This paper discusses the experimental findings on the influence of various factors on the rate of removal of impurities, such as the impurity inter-effects, initial oxygen content in the metal and injection rate of SF6.

Jan 1, 1995

By László I. Kiss, Verena Mackowiak, Alexandre Perron, Dominic Toulouse, Alicia Liedtke, Sándor Poncsák

"Bubbles play a very important role in different metallurgical applications like for example in electrowinning. During heterogeneous nucleation, the maximal size of the bubbles growing at the nucleation sites as well as the nucleation frequency is determined by the so-called detachment condition. Detachment occurs when the external forces acting on the bubble exceed the retaining forces along the solid-gas-liquid triple interface line. The phenomenon depends strongly on the shape and orientation of the solid surface and on the nature and strength of the external buoyancy and drag forces. In the present study the detachment conditions of bubbles from downward facing horizontal and inclined plates were studied experimentally under the effect of gravitational and hydrodynamic forces. The results show the deformation of the bubbles under the effect of the external forces and the detachment conditions as function of the bubble volume.IntroductionIn heterogeneous nucleation bubbles are generated at the so-called nucleation sites along the solid-liquid interfaces. They continue to grow there and after they reached a certain size they detach from the solid surface and leave the nucleation site. This scenario is well known both in boiling and electrolysis. During the growth period a stable equilibrium exists between the forces that retain the bubble at the nucleation site and the forces that try to remove it. This equilibrium evolves with the increasing volume of the bubble to the point when the detachment forces overcome the retaining forces.The life of a single bubble generated by heterogeneous nucleation can be divided into two periods separated by the detachment - or in other words by the departure - of the bubble: first the growth at the nucleation site and then the movement away. The knowledge of the detachment conditions makes possible the determination of the maximal volume of the bubble at the nucleation site that, in tum, makes possible the determination of the nucleation frequency. This is why so many researches have been directed toward the clarification of the details of the bubble detachment in the past decades. The equilibrium between the attaching and separating forces depend on the presence of body, surface and flow induced forces in the liquid, on the geometry and orientation of solid surface, on the properties of the solid-liquidgas system etc."

Jan 1, 2004

By Zhi-xiang Cui

Effects of flux, vulcanizing agent and reductant on slag cleaning in new-type slag cleaning furnace (Φ3.6 × 8.1 m) were investigated under the conditions including smelting temperature of 1200 and 1250 °C, settling time of 30 and 60 min, and Fe/SiO2 of 1.7–1.9. The results show that addition of SiO2, B2O3 or CaF2 into original copper smelting slag can improve settling separation effect. Though no effect on copper recovery, addition of FeS can provide heat required by reaction with oxygen and reduce copper dissolution in spinel phase and slag. Copper content in discarded slag can be controlled at 0.26% under the optimum comprehensive conditions with ratio of oxygen to natural gas of 1.6.

By C. H. Bucknam

A review of phase analysis methods used to characterize refractory gold ores is presented. Updating of assay methods using database technology, on-line instrument interfacing and response surface modeling is highlighted. The use of assay results to classify ores for metallurgical purposes is demonstrated.

Jan 1, 1987

By Thomas F. Nederpel

The production of zinc and zinc-aluminum coated strip can be reasonably accomplished on a single operating unit. However, if the hot dip coating line is equip d with only one mo 7 ten metal holding furnace, it is necessary to transfer liquid metal of different chemistries and reintroduce virgin material to obtain the 18" necessary balance of elements in the bath. Dofasco produces Galvanize and Galvalume on a coating line with a sin le liquid metal furnace and has developed not only an efficient liquid metal trans& system but also an effective means of reutilizing the zinc-aluminum mixtures without detrimental quality affects.

Jan 1, 1992

By Sugui Tian

By means of the T6 treatment, the measurement of creep curves and microstructure observation, the influence of T6 heat treatment on the microstructure and creep properties of Ti-6Al-4V alloy is investigated. Results show that the microstructure of the forged alloy consists of the banded-like a phase and networks b phase. After sub-temperture T6 treated, the microstructure of alloy consist of the block a phase and ?networks basket? structure. Under the conditions of the applied stress of 575 MPa at 4000C, the forged alloy displays a lower creep lifetimes, after T6 treated the creep lifetimes of the alloy is enhanced to 548 h from 66 h, which is attributed to the formation of the network basket structure in which the needle-like phase are dispersedly distributed. As creep goes on, the denser dislocations in the a phase are concentrated to occur the dynamic recrystallization for refining grain. which is a main reason of the alloy displaying a better creep lifetimes and plasticity. Thereinto, the creep mechanism of the forged alloy is thought to be the slip of the straight <a> and <a+c> dislocation are activated on the prismatic planes and pyramidal planes, while the creep mechanism of T6 treated alloy is that wave-like <a+c> dislocations are activated on the pyramidal planes.

Jan 1, 2009

By William Petruk

The capabilities of SEM/image analyzers for determining quantitative mineral data which have a bearing on extractive metallurgy have given applied mineralogy a new dimension. The capabilities include automatic mineral identification, unattended operation, search for rare minerals, and measurements of (1) mineral quantities, (2) grain and particle size distributions, (3) liberation characteristics of minerals in ground ores, and (4) mineral associations. Data on mineral quantities define the distributions of elements among minerals, provide background information on characteristics of the samples, and provide a data base for a mineral-materials balance. Size analysis data of the minerals in unbroken ores are used to predict the grind required to liberate minerals. Data on liberation analysis can be used in many ways. One application is to process the image analysis data for feed, concentrate and tails by a materials balancing technique to calculate the recovery of liberated and unliberated grains at each point in a circuit. The calculated recovery data define the behaviour of an ore in a concentrator, pilot plant or bench test, and indicate whether recovery improvements are possible and/or feasible for a particular ore.

Jan 1, 1991

By Nickolas J. Themelis

Nearly thirty two million tons of municipal solid wastes (MSW) are combusted annually in over one hundred U.S. Waste-to-Energy (WTE) power plants, thus reducing the use of fuel oil by about 1.6 billion gallons of fuel oil One of the advanced WTE processes is the 0.9-million ton/y SEMASS facility at Rochester, Mass. Most of the combustion in the three giant combustion chambers occurs while the injected shredded wastes are in suspension, i.e., in flash combustion mode. The velocity, temperature, and concentration profiles in the SEMASS combustion chamber were simulated by representing the combustible fraction of MSW by the simplified formula C6HIO04 and using the CFD program Fluent to solve the turbulent energy and mass transport equations. After validation against plant data, this model will be used to examine options for increasing the productivity of WTE combustion chambers, such as optimum distribution of primary and secondary air and oxygen enrichment.

Jan 1, 2003

By Stephen Gale, David Clarry, Edmund Smith, Jon Feldman

"In 2006, a Canadian steel maker embarked on an ambitious initiative to become “Best in Class in Energy Management”. This initiative provides the framework for this paper, with some augmentation from other energy management projects carried out by Hatch. The initiative focused on identifying energy/GHG management improvements leading to low-cost implementation of energy savings or GHG emission reduction. The key components of the approach were:• Review site energy management practices and benchmark internationally.• Review best technical practices and benchmark against public energy intensity data.• Conducted a site-wide Energy Assessment and physical review of operating areas.• Facilitation of on site-workshops with staff to prioritize savings opportunities, as well as identify and remove implementation barriers.• Development of an Energy Management Action Plan for implementation of improvements.Most organizations can produce, with relative ease, a list of ideas for saving energy, implementing them is the challenge. This paper addresses these issues as well as the profitability of the energy efficiency improvements and the consequences for GHG emissions.IntroductionWhen one of the authors was an undergraduate engineering student at the University of Cape Town in South Africa, the technical drawing instructor made a statement that was both humorous, and mildly profound. He claimed that the most successful engineer is one who is both lazy and diligent. Lazy, in the sense that the engineer is constantly on the lookout for an easier, more efficient, way to do something. Diligent, in the sense that the engineer will work tirelessly to come up with a good technical solution for the easier way. This paper, somewhat of an anomaly in a compilation of technical proceedings, hopes to break the mould a little, and to show a “lazy-diligent” way of reducing the carbon emissions from an industrial facility, using a steel plant as an example."

Jan 1, 2008

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 Mikula Adolf

Lead-tin solders are commonly used in electronic packaging due to their unique combination of electrical, chemical, physical, thermal and mechanical properties. Since it is known that lead and lead containing alloys cause great environmental concern and health hazards it is necessary to replace lead in solder materials. Besides the environmental concerns new technologies in electronic packaging require new and improved solders. In most cases the new solders will consist of temary or quarternary alloy systems, the main component will be tin or indium and the second element could be bismuth. silver, copper and gold and to improve certain properties a third element will be added. For a third element zinc, nickel, antimony and aluminum can be considered. This report will concentrate on solders containing zinc as an environmental safe. element.

Jan 1, 2003

By E. A. van Dijk

Dusts from steel-making processes contain substantial amounts of zinc. Such dusts are also a hazardous waste and dumping them becomes unacceptable from environmental point of view. Therefore processes that can recover zinc and possibly other metals from steel-making dusts are being investigated. The aim of this paper is a contribution to the more fundamental kinetic aspects of zinc reduction from silica free calcium ferrite slags. The effects of alumina, lime and magnesium oxide contents of the slag, the COICO, ratio and the effect of initial Fe2O3/CaO ratio were studied experimentally at 1400°C The results indicated that the reduction of zinc from molten slag was possibly a first order reaction. As expected higher COICO, ratios increased both the extent and the rate of reduction. It was also observed that a higher iron content of slag improved the reduction of zinc from calcium ferrite slags. This fact seems to support the proposed mechanism that zinc is partly reduced by ferrous iron to zinc vapour and that ferric iron is reduced by carbon monoxide. The reduction rate of zinc in these slags was decreased by increasing alumina content of the slag. Alumina decreased the calculated optical basicity of the slag showing the fact that reduction of zinc oxide was more favorable in more basic slags. Probably the formation of complex ions by alumina and zinc oxide such as ZnAl2O32+ lowers the activity of Zn2+ ions in the slag and hence render them more difficult to reduce.

Jan 1, 1999

By Jingyuan Wang, Hengyi Zhang, Peng Lan, Ruitian Zhang, Jiaquan Zhang, Yang Li

"For the determination of mould taper and wall thickness, a 3-D numerical model of ingot-mould-hot top system has been made to evaluate the related ingot solidification process and the final soundness. The effect of mould wall thickness and the taper of its hot faces on the thermal history and the as cast structure of steel ingot has been revealed through the numerical simulation. It is shown that the ingot soundness can be improved remarkably by increasing the mould wall thickness, which is possibly beneficial to the mould life as well owning to an improved mould thermal state. The mould taper is vital to the ingot soundness but much less coherent to the mould temperature profiles. Under given casting situations, a larger mould taper can lead to a less intensity of the shrinkage porosities at the top part of ingot.IntroductionIngot casting is still one of important processes for steel production, which is adopted especially for the supply of large-sized semi-products of high quality special steels. The understanding to the solidification process is vital to both the yield improvement of casting production and the quality control of steel ingots, such as their soundness and homogeneity.The ingot processing and service performance are closely related to its defects, such as porosities and pipes[1,2], which are the most common but serious defects during ingots casting. In the late 1960s, Mahadevan and Murthy et al.[3], Irani and Kondic[4] began to analyze criteria for the prediction of shrinkage porosities in light metal casting. In 1980s, Niyama and Uchida[5], Hansen and Sahm[6,7] et al have successfully presented some related porosities and pipes criteria for steel casting. At the same time, numerical solidification simulation was well developed and applied to ingot quality studies[8-10]. However, due to the quick development of continuous casting, less emphasis has been given to the further study on ingot casting process. There leaves much work to be made for the comprehensive understanding to ingot quality improvement and the mould design by the aid of modern solidification technology[11, 12]. In this paper, the effects of mould taper and wall thickness on its thermal history, ingot solidification and the final soundness are numerically studied through solidification simulation, which has been adopted in mould design and industrial production of both the mould and its steel ingot."

Jan 1, 2012

By Ricardo A. Valls

The Sechol Nickel-Cobalt Laterite Project is located in East-Central Guatemala, 140 km northeast from Guatemala City. In-situ resources in the immediate Sechol area, including those on other mining concessions contain 133 million tonnes of mineralization, grading 1.5 1% nickel. Considering the ever-increasing market for these metals, and the potential quick return on the initial investment, Jaguar Nickel Inc. is confident that by late 2006, it will be producing the first nickeltcobalt hydroxides from Guatemala. The path from now until the production stage passes through a pre-feasibility study, scheduled for completion by mid 2004, and bankable feasibility by mid 2005. Jaguar&apos;s objective, however, is not only to have a producing nickel-cobalt mine by late 2006, but also to continue with the exploration work in order to make Guatemala one of the world&apos;s leading nickel-cobalt producers. The Sechol group of deposits is conformed of several lateritic pockets, delimited by tectonic faults, and hosted by ultramafic rocks of the Sierra de Santa CW. ophiolitic belt that intruded the Maya Continental Block during the Early Tertiary age. The intrusive is mainly represented by a layered sequence of dunites, peridotites, and pyroxenites, usually strongly serpentinized. Existing data indicate that these rocks underwent fractional crystallization, and probably some degree of magma mixing and contamination previous to their main tectonic event. The most complete profiles are usually present over weathered dunites and serpentinites, while on top of the less altered pyroxenites, there is usually the formation of only a limonitic zone. The relative complexity of the ophiolitic belt explains the variety of mineral resources in the area, which include Ni-Co-Fe laterite, chromite, bauxite, magnesia, and also has the potential for gold, PGMs, and precious and semi-precious stones such as jade, nephrite, and chrysoprase. Metal recovery from the Sechol deposit will be based on an atmospheric chloride process, followed by solution purification, production of an intermediate nickellcobalt hydroxide suitable for sale, and finally acid and magnesia recovery by standard spray roasting technology. The chloride process will allow exploitation of the whole lateritic profile to produce 20,000 Mt of nickel hydroxide and 800 Mt of cobalt hydroxide per year. The exploration work completed to date has concentrated mostly on the Sechol group of deposits, representing less than 5% of the current land position of Jaguar in Guatemala. Within Sechol, the company has identified a large pocket of more than 5 Mt of laterites grading 2.1% nickel and 0.08 % cobalt as a startup pit "El Inicio". Including the work previously completed Keywords: Laterite deposits, Ophiolitic Belts, Central Guatemala, Nickel, Cobalt

Jan 1, 2004

By J. Bostjancic

As wastewater discharge regulations become more stringent, power plants, manufacturing plants and other industrial sites are looking for ways to reduce makeup water requirements and to recycle and reuse as much wastewater as possible. In some cases, environmental regulations require zero liquid discharge, meaning all wastewater must either be retained on site or reduced to solids for disposal off site. Zero liquid discharge or "closed-loop" wastewater treatment systems using evaporators and other process equipment have been well-accepted in recent years. Often overlooked is the fact that zero discharge is not just the latest fashion--many commercial zero liquid discharge systems have been in operation since the mid-70&apos;s. This paper will give specific examples of zero liquid discharge operations from 1974 to the present, showing how evaporation equipment and processes have changed to meet the requirements of industry and environmental regulations.

Jan 1, 1996

By Adolf Mikula

Lead-tin solders are commonly used in electronic packaging due to their unique combination of electrical, chemical, physical, thermal and mechanical properties. Since it is known that lead and lead containing alloys cause great environmental concern and health hazards it is necessary to replace lead in solder materials. Besides the environmental concerns new technologies in electronic packaging require new and improved solders. In most cases the new solders will consist of ternary or quarternary alloy systems, the main component will be tin or indium and the second element could be bismuth, silver, copper and gold and to improve certain properties a third element will be added. For a third element zinc, nickel, antimony and aluminum can be considered. This report will concentrate on solders containing zinc as an environmental safe element.

Jan 1, 2003

By Edmundo Manilla, Merete Tangstad, Daniel Davila, Eli Ringdalen

FeMn alloys are typically produced with lumpy ore or sinters. Minara Autlan, the Mexican FeMn producer, is however making Mn-nodules as a raw material for Mn-alloy production. The Mn nodules have been characterized by XRF, XRD, by wet chemical methods and by EPMA. The Mn/Fe ratio is somewhat lower compared to commercial Mn ore on the marked. The basicity of the ore is however close to 1, and additional fluxes may not be used. The Mn-nodules will be in a state of manganosite (MnO), tephroite ((Mn, Ca)2SiO4) and galaxite ((Mn,Mg)Al2O4). This leads to a low melting temperature area. A low porosity and low amount of higher Mn-oxides gives a high thermal strength to the nodules.

Jan 1, 2016

By Pengfu Tan

In order to understand and control the formation of dioxins and furans in iron ore sinter plants and to possibly avoid expensive end-of-pipe removal stages, thermodynamic calculations on the stability of PCDD/Fs have been combined with sinter process modeling by means of kinetic simulations and computational fluid dynamics. Three thermodynamic databases of PCDD/Fs, derived using the Group Additivity approach and two computational molecular modeling methods, MNDO and PM3, respectively, combined with the SGTE database have been used to model the PCDDIF formation and the PCDD/F isomer distributions in iron ore sintering. The results show very similar conditions for the PCDD/F formation using the different databases. Concerning the isomer distributions of toxic PCDD/Fs, the calculated data derived from the MNDO method showed optimum agreement with measured values from industrial furnaces. The thermodynamic calculations also proved that the isomer distributions found in combustion processes are equilibrium values, while the concentration ratio of PCDDs and PCDFs in the wind boxes does not represent an equilibrium state. A CFD model of iron ore sintering was developed including the kinetics of 15 relevant chemical reactions with the aim of describing the temperature fields and the gas flow patterns in the sintering bed. On the basis of these information and experimental observations reported in the literature possible pathways for the PCDD/F formation in sinter plants have been identified: PCDD/Fs are formed in the critical temperature region of 250 to 450°C below the combustion zone, are then carried downwards with the gas and condensed close to the bottom of the sinter bed. Transported to the discharge end with the solid mixture, they are again released into the gas phase when the flame front approaches the bottom. PCDD/Fs are also formed in the last wind boxes when the hot off-gases cool down and reach the critical temperature range. Consequently, methods to reduce the dioxin formation reactions are proposed including inhibitor addition to the sinter feed and off-gas quenching.

Jan 1, 2003

Achieving continued economic growth with social equity within the natural limits of the Earth&apos;s &apos;eco-systems is the major issue facing the world today. The material and energy needs of the world cannot be met with the current ways of addressing this issue. The need for metals, an important class of materials, will continue into the future because their unique properties make substitution by other materials impossible in many applications and this need will continue to be met from primary metal production and recycling. However, the recycling rate will increase and the usage pattern of metals will change to reflect the environmental impact of their production and use. Pyrometallurgy has an important role in meeting the metal needs of the future since some metals can only be produced pyrometallurgically; the energy required to produce some metals pyrometallurgically is significantly less than by other methods; most metals are most efficiently recycled pyrometallurgically; and the release of harmful and toxic elements into the biosphere can sometimes best be controlled through pyrometallurgical processing. The development of strategies for pyrometallurgical processing for the future lies in the recognition that sustainable development calls for large step improvements in value delivered per unit of environmental impact over the entire supply chain. Pyrometallurgists can respond to this challenge by contributing to reducing the environmental impact of meeting metal needs using three broad strategies: "end-of-pipe" approaches to convert emissions into benign materials for storage or disposal; flowsheet redesign to limit or eliminate emission production; and improved recycling technologies. A number of examples are discussed to illustrate how the sustainability driver is already influencing the technological development of pyrometallurgical processes, and how these will develop further as the sustainability driver strengthens.

Jan 1, 2003

By Chunlin Chen

Nickel-sulfide minerals are normally associated with copper and iron sulfides and often contain a minor amount of valuable metals such as cobalt and detrimental impurities such as arsenic. Metal losses in slag vary from process to process during the pyrometallurgical production of nickel and, depend on the feed composition, slag chemistry and operating conditions. Maximiz the metal recovery is one of major considerations to optimize operating condition for nickel smelting/ converting processes. At the same time, the deportment of minor elements between various phases during nickel smelting is of great importance by smelter operators. The Multi-Phase Equilibrium (MPE) is a thermodynamic package developed by CSIRO for simulating reactions between phases in multi-component and multi-phase systems [1]. Over the years the capability of the MPE model has been extended to cover the behavior of a large number of elements in high temperature systems. The sulfide smelting module of the MPE, which covers the minor elements such as As, Bi, Sb, Pb, Se, Te, Sn, Co and Zn, is capable of modeling the deportment of major and minor elements between various phases during nickel smelting. In this article the application of the MPE model in modelling the nickel smelting process is presented. The modelling results on the majors and minors are compared with the plant data. The deportment behaviour of arsenic in nickel smelting was analysed and the impact of slag chemistry on slag properties was modelled. These results can assist process metallurgists in exploring the optimum fluxing strategy for smooth operation and the potential practices for improving arsenic removal.