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By Robert Matusewicz

Ausmelt Technology has been applied to the recycling of spent pot liner (SPL) generated from primary alnminum production. The process is centered on the Ausmelt furnace, in which the SPL is converted under high temperature, oxidizing conditions to an HF containing gas stream and inert slag. fluorine is recovered from the SPL as HF gas and is concentrated and used to manufacture AIF) for recycle to the aluminum smelters. Approximately 87% of the fluorine can be recovered and converted to AIF), with the remainder being effectively tied up in the by product slag. Cost projections show that the recycling process will be competitive with other processes for SPL. The production and recycling of AIF) provides available credit that significantly offsets the operating cost of the facility. Ausmelt Technology for recycling of SPL is currently being marketed in North America by Ausmelt Technology Corporation in Denver, Colorado, and in the rest of the world by Ausmelt Limited of Dandenong, Australia.

Jan 1, 1996

By David Rees

Tomago Aluminium, a 400,OO tonnes per annum primary aluminium smelter in Australia, has installed Ozone for biological control of its process water. The system was designed in Australia by Ionics Watertec Engineering, whilst ANCO Australia monitors the water quality and provides technical support for the project. The motivation was initially to reduce operating costs, however investigations indicated that there were substantial environmental benefits to be achieved by the elimination of a part, or all of, the chemicals being used to control the system. Also the existing chemicals appeared to be losing their ability to control biological growth in the system, in particular, the legionella bacteria. Ozone water treatment commenced in January 1998 and after a short transition period has operated without chemical addition since. There appears to be no doubt that the biological control is effective, the clarity and purity of the water has improved and initial testing indicates that the corrosion control rate is acceptable, although some chemical corrosion control may be introduced after further testing around the total circuit to guarantee protection

Jan 1, 1999

By Heikki Jalkanen

The mineralogical composition and morphology of solidified copper smelting and converting slags are of some interest from slag cleaning (by froth flotation), impurity elimination, and environmental points of view. Properties result from both the state of molten slag before solidification and processes taking place during solidification and cooling. In solidification and cooling, copper and sulfur dissolved in molten slag are .precipitating substantially from the silicate phase. Even in water quenching of slag, dissolved copper is pushed out of the solution in the form of finely divided precipitate. Elements present in the raw materials are distributed in a distinct manner between the solidified slag and non-silicate solidification products. Arsenic, antimony, and tin are strongly accumulated in copper precipitate, but not the other metallic constituents common in copper concentrates. Smelting and converting slags differ remarkably on their mineralogical composition and morphology although resulting principally of same chemical processes. Converter slags are more inhomogenous; they often contain solid particles and copper content is .as a rule higher than in matte smelting slags. The final copper content of converter slags was observed to be in a distinct manner dependent on iron oxide - silica ratio. Slag forming, solidification, and precipitation phenomena are discussed on the basis of mineralogical and morphology analysis of smelter slags and laboratory scale experiments.

Jan 1, 2002

By F. San Martin, Y. Lefevre, F. Tamargo

The San Juan de Nieva smelter was commissioned in 1960 with an electrolytic zinc capacity of 15,000 t/y. After a number of minor expansions, the capacity was increased to 320,000 t/y in 1991 and will reach 440,000 t/y by August 2001. The expansion involves the construction of a 900 t/day Lurgi roaster and a new acid plant. The leaching will be fully revamped and modernised, including the construction of a new building for residue treatment and for j arosite precipitation with a separate circuit for silver-containing concentrates. The project also includes the construction of a fully automated 137,000 t/y zinc cathode tankhouse fitted with 3.4 m2 cathodes designed by Asturiana de Zinc, and based on the existing tankhouse and introducing some improvements. New melting and casting facilities, also designed by Asturiana, will be constructed.

Jan 1, 2000

By Y. Yang, S. Peelman, J. Sietsma, Z. H. I. Sun

The rare earth elements (REEs) present in the Kiruna iron ore mine tailings are being considered as a new REE resource for the EU. These tailings, after beneficiation, contain approximately 5000 ppm of rare earths, concentrated in apatite and monazite minerals. To economically extract the REEs from these tailings the phosphorous contained within the apatite must also be extracted and the waste production of the process should be minimal. To achieve the extraction of REEs and phosphorous HCl and HNO3 were investigated as possible leaching agents. Based on the results a leaching process using HNO3 is proposed. This process produces H3PO4 from the apatite while simultaneously dissolving the REEs. The resulting leach liquor is then cooled to remove the unwanted Ca as Ca(NO3)2. Analysis of the leach liquor reveals extraction ratios of between 75% and 100% for the heavy REE (e.g. Y, Eu, Dy, …) and below 40% from the light REEs (i.e. Ce, La). Full phosphorous extraction was also achieved.

Jan 1, 2016

By John R. Goode

Barrick Gold Corporation operates gold mines in the United States, Chile, 'Peru, Canada, and in the near future, in l1anzania. Barrick meets environmental requirements and limits the potentially adverse effect of cyanide discharge to the environment using various cyanide destruction techniques. Barrick operations use, or have used, natural degradation, ferrous sulphate, hydrogen peroxide, Caro's acid, alkaline chlorination, and the SO/Air process for cyanide destruction. This paper presents a general discussion of the options for controlling cyanide in plant effluent and provides details of Barrick's operating experience including general notes on costs.

Jan 1, 1998

By Wang Shulan

The synthesis process of BaTiO3 from TiO2 and BaCO3 in the molten NaOH-KOH at 350oC was studied by the A.C impedance technique. The A.C. impedance of molten NaOH-KOH (xNaOH = 0.36) and the variation of the conductivity of the salt with time during the synthesized process were measured. The synthesized reaction of the BaTiO3 and the decomposition reaction of BaCO3 are fast and were finished in 10min. The interaction between TiO2, BaO and BaTiO3 and the molten salt was confirmed by the variation of the conductivity.

Jan 1, 2005

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 Hani Henein, J. Barry Wiskel

"The easy accessibility and power of the PC, as well as the education of our engineering students in the use of these tools, are compelling reasons for developing computer aided instructional (CAI) tools. There are a wide range of areas in the engineering curriculum where students must learn the steps and the process of applying judgement in problem solving. In the typical course instruction, · an instructor introduces theory to students; the application of the theory to solving problems is often demonstrated in the abstract. Students therefore spend a significant amount of time learning how to apply the theory to problem solving. Additional time and effort must then be spent to get students to the point of learning concepts and integrating this knowledge. A number of computer aided packages have therefore been developed for use in several courses in the materials science and engineering curriculum that encompass both calculational and instructional capabilities. This paper presents an overview of some of these packages which include the solution of a non-linear equation, the instruction of binary diffusion couples, an introduction of crystallography, an introduction to heat transfer and the solution of thermodynamic stability diagrams. The context in which these CAI Tutorials were developed and are being used will be discussed. The pitfalls in the development of these packages will also be discussed. The use of the tutorials has important implications on the expectations from an engineering education of both instructor and student.IntroductionTraditionally, it is quite routine to teach engineering students how to use a computer (the PC today for undergraduates) as a tool in performing engineering calculations or in simulating a process or a unit operation. This often takes the form of one course in computer programming, whether it is Fortran, Visual basic or a spreadsheet, and another course in numerical computation. However, the materials and electronic revolution have brought about considerable advances in computer power and speed, and accessibility. Today, the manipulation of digital images, movies, and speech are commonplace on a desktop PC.' Many mathematical models that were executed only on workstations can now be readily handled on a PC. Concurrently, more of our students own a PC even if their curriculum does not require them to purchase one. Today, virtually every university student has been introduced to the PC in either their elementary or high school education. Hence, the increased capabilities and accessibility of the PC and the familiarity of students with this tool make it compelling to explore its use as an educational tool for our engineering students. This is not a traditional role of a computer in our engineering curriculum."

Jan 1, 2000

By W. F. Whittaker

Systematic control of process parameters during electrorefined copper cathode production and final product inspection ensures high quality of produced "ORC brand copper. Since 1986, substantial increases in tankhouse productivity have been achieved by a number of technological and process control changes. This paper reviews the changes implemented to achieve higher productivity and cathode quality.

Jan 1, 1992

By Don Eby

The application of electric arc furnace smelting of lead, antimony, and tin bearing slag from a reverberatory furnace will be discussed. The selection procedure for the 4.0 MVA electric arc furnace in Indianapolis, Indiana is presented. The design criteria for the transformer, electrodes, refractories and associated equipment is presented. The operation of the furnace including chaJ:9ing, bullion tapping, slag tapping, ventilation, slag composition, metal recoveries, and toxic leach results of thra.1 away slag are discussed. Flow charts and the equipment specifications are given.

Jan 1, 1990

By P. N. Anyalebechi

"The effects of solidification rate, initial melt hydrogen concentration, and grain refining on porosity formation in aluminum alloy 2024 have been investigated with unidirectionally cooled laboratory-size ingots. The ingots were prepared from melts containing hydrogen concentration of 0.059-0.27 cm3/100 g and solidified at 0.2-37 °C/s. As expected, the amount of porosity, average pore size, and pore number density increased with increase in melt hydrogen concentration and decrease in solidification rate. However, the effect of solidification rate was greater at the very low melt hydrogen concentration (0.059 cm3/100 g). These results are consistent with reported effects of solidification rate and melt hydrogen content on porosity formation in other aluminum alloys. Interestingly, addition of grain refiner slightly increased the amount of porosity and the average pore size, especially at solidification rates above 1°C/s. IntroductionIn shaped castings and wrought products fabricated from ingots, billets, bars, or slabs of aluminum and its alloys porosity formation is a problem. This is because it compromises their tensile strength, fracture toughness, and fatigue properties [ 1-18]. The pores are usually the crack initiation and propagation sites [6,8,9] and the largest pores tend to dictate the fatigue life of the aluminum products [9,10,14]. Porous regions within an aluminum product probably yield first due to the reduced tensile load bearing capacity, causing the concentration of the strain near the voids which subsequently results in premature fracture. In aluminum alloy ingots, billets, bars and slabs porosity formation is particularly problematic because of its persistence through fabrication and potential for reappearance or exacerbation during subsequent thermal treatment processes before and/or after fabrication [19]. In fact, persistence of microporosity is a serious problem in large thick plates of wrought aluminum alloy products that must be rolled from correspondingly large direct-chill or electromagnetic cast ingots. Some of these thick plate products are machined into large aircraft components that are required in service to withstand multi-directional stresses and to possess high fatigue strength, fracture toughness, resistance to stress corrosion cracking, and strength in the short-transverse direction [1,20]."

Jan 1, 2011

By C. A. Young, J. D. Miller

Adsorption isotherms previously determined by in-situ Fourier transform infrared/internal reflection spectroscopy (FT-IR/IRS) for oleate adsorption at calcite and fluorite surfaces near pH 9 and at various temperatures are compared. Results indicate that, at both mineral surfaces, chemisorption occurs at equilibrium concentrations below approximately l x l0-5 M oleate while calcium dioleate surface precipitation occurs at higher equilibrium oleate concentrations. The extent of chemisorption at the calcite surface is 3 to 5 times less than that at the fluorite surface while the extent of calcium dioleate surface precipitation on calcite is nearly a magnitude larger than that on fluorite. However, for both minerals, surface precipitation decreases with increasing chemisorption. Contact angle measurements and flotation recoveries show the hydrophobicity of fluorite to be greater than that of calcite at each of the temperatures and oleate concentrations studied. Significant differences are noted only in the chemisorption region. Unlike calcite, the hydrophobicity of fluorite was sensitive to the presence of oxygen in the system. Multichannel Laser Raman Spectroscopy (MLRS) showed this behavior was caused by the double-bond reactivity of adjacent chemisorbed oleate molecules and subsequent formation of an epoxide/polyether complex at the fluorite surface. Such a reaction product could not be detected at the calcite surface. These differences in adsorption density, hydrophobicity, and polymerization behavior are discussed in terms of the intrinsic surface properties of the minerals.

Jan 1, 1999

By Stanko Nikolic

One of the keys to success in process development is incremental scale-up, allowing for potential problems to be identified and rectified. The ISASMELT™top submerged lance (TSL) process was developed to maturity using this method by Mount Isa Mines, now owned by Glencore. Commercialization only occurred once the process had been proven on each scale and as a result the ISASMELT™ technology now operates successfully around the world. An important parameter in the evolution of the technology has been the furnace campaign life. The initial commercial scale furnaces had minimal water-cooling. Although this led to shorter campaign lives, an extended development program resulted in the achievement of four-year campaign lives, without any water cooling. In tandem to the refractory designs Glencore Technology, supplier of the TSL technology, has progressed cooled copper lining designs for application to both the ISASMELT™ and ISACONVERT™ furnaces allowing for ultimate flexibility in the lining choice. This allows each ISASMELT™ operating site to minimize their overall life-cycle costs by balancing their campaign life with lining costs, energy inputs, and other shutdown requirements.

By David Norval

Water solidification of mattes, metals, alloys and certain slags with high metal entrainment has customarily not been practiced due to the belief that such processes are too dangerous and unproven in the Pyrometallurgical Industry. Slag granulation on the other hand is extensively applied, although in some cases crudely, with disastrous effects, as a result of not recognising the high heat capacities prevalent in slags. This paper will examine the most common air solidification processes and compare such processes with water solidification, mainly slag and matte granulation processes and design criteria for safe and reliable operation. Finally, purpose designed granulation and solidification processes will be discussed taking into account specific applications and the individual signatures of alloys and slags, emphasising that no slag, matte or alloy responds in similar fashion to a granulation practice.

Jan 1, 2006

By Ph. Cauwe

This paper presents the experience that NESA and MECHIM have gained about recovery of non ferrous and precious metals from complex sulfide materials. Processed materials are from natural deposits or metallurgical by-products or residues. Roasting of these materials is closely related to the pyro or hydrometallurgical processes used downstream of the roasting. Conditions of a first step of roasting the SELECTIVE ROASTING, are analyzed and explained. The roasted products so obtained are characterised by an extended elimination of volatile sulfides (AS, Bi, Sb, Sn, Pb, Hg, ?? ) and are readily available for the pyrometallurgical recovery of non ferrous and precious metals. After the SELECTIVE ROASTING, thanks to. the high porosity obtained in the "selective calcine", the SULFATE ROASTING is per-formed in excellent conditions. Hydrometallurgical tests performed for the final calcine show a high recovery of non ferrous and precious? metals and require only simple and well known processes. Many experimental and commercial data are given.

Jan 1, 1983

By Balasivanadha Prabhu, Prasad P. Shanmugasundaram, Narayani Narasimhan

"The grain refinement and mechanical properties of 6061 aluminium alloy produced by equal channel angular pressing (ECAP) have been analyzed in this present study. A innovative triple shear ECAP die was developed for the processing.It was observed that the grain refinement takes place for greater number of passes. It was also found that reducing the process temperature gives fine grain and high microhardness and hence improved propertiesIntroductionTechnological changes in manufacturing industries have depended heavily on development in materials processing and process technologies. Modem industries need high performance materials for severe service conditions. Hence, it is necessary to improve required material properties to achieve better performance and greater service life. As mechanical properties of the materials strong! y depend on grain size ( d) - Hall-Petch relationship [ 1-4], the ultrafine grained (UFG) materials offer superior mechanical properties based on the above relation.Synthesising massive nanocrystalline materials presents a challenge to basic research as well as to application-related processing efforts. Production of ultrafine gram microstructures in metals and alloys having different crystal structures but always an initially coarse microstructure using severe plastic deformation can significantly enhance the physical and mechanical properties of materials. Severe Plastic Deformation (SPD) is an efficient method to induce ultra fine grained structure in materials by deforming it to large strains. Traditional techniques for introducing deformation of higher strains, such as forging, extrusion, drawing or rolling do have the inevitable limitation on required equipments of exerting enough load or pressure to cause uniform nanometer level grain refinement."

Jan 1, 2011

By William E. Torres

The Southern Peru Limited smelter, in Ilo, operates two reverberatory furnaces, seven Peirce-Smith converters, one Teniente Converter, two casting wheels and a single contact acid plant. The Teniente Converter was commissioned in August 1995 and was designed to smelt 744 dry metric tons (820 dry short tons) of concentrate per day. The process off-gas is collected in a water-cooled hood, cooled in a spray chamber, and cleaned in a Joy electrostatic precipitator for further treatment in the Acid Plant. This paper presents the current Teniente Converter operating practices and control philosophy. Relevant improvements and modifications to achieve a 379 day campaign without tuyere replacement and a daily average smelting rate of 862 dry metric tons (940 dry short tons) of concentrate are discussed.

Jan 1, 1998

By Z. M. Zheng

Cyclic voltammetry, potential step, and ac impedance techniques were applied to study the electrochemical reaction of arsenopyrite in chloride solutions. The relationship between anodic current density and time in potential step measurements indicates that the oxidation of arsenopyrite is irreversible. The results of the constant potential coulometry show that the stoichiometric factor of the total electron involved in the overall reaction is 14. It is proposed that the dissolution of arsenopyrite is retarded by coverage of sulfur produced in the reaction as an intermediate product. The measured results of ac impedance strongly support the proposition. The proposed reaction mechanism also explains satisfactorily the charging current density and Tafel slopes measured in potential step measurements.

Jan 1, 1995

By I. Gaballah

Cadmium is toxic to plant, animals and humans. The council directive of the European Communities No 8315 13lEEC has fixed an upper limit of 200 ppb for the release of cadmium in industrial effluents. The conventional method of neutralization/prccipitation ( NIP ) is inefficient to reach this limit. The objective of this study is to test the efficiency of the trees modified bark to remove cadmium cations from industrial effluents after the conventional treatment by NIP. Laboratory scale tests with synthetic solutions show that the cadmium removal depends upon pH and initial concentration. About 99.9 %, 99 % and 96 % of the metal are removed from synthetic solutions containing 10, 100 and 1000 ppm respectively. Pilot plant trials ( 1 m3 ) with an industrial effluent bearing about 500 ppb of cadmium lead to the almost complete elimination of the cadmium ( final concentration is lower than the analytical detection limits < 20 ppb ).

Jan 1, 1994