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By Dale W. Collins

The disposal of arsenic from copper operations possess various health, environmental and processing problems. There are basically two areas of concern. The first being the disposal or treatment of smelter flue dusts and the second the removal of arsenic from refinery electrolytes. A number of treatment options have been proposed including the addition of soluble arsenic wastes to copper heap and dump leaching solutions. This approach will allow arsenic to be reintroduced to the ore via Solvent Extraction (SX) raffinate associated with hydrometallurgical operations. Knowledge of the attenuation behavior and mechanism during leaching is important in determining the long term stability of arsenic and the success of this approach. Parameters, such as uptake capacity, pH, particle size and solution chemistry have been investigated. Arsenic attenuation has been examined using column leaching with experiments employing both continuous flow and pulsed additions of As(V). In the initial stages of leaching, the attenuation of arsenic appears to depend on the pH and iron concentration in the effluent. Arsenic stability in the copper oxide ore has been examined with rinses of progressively lower pH.

Jan 1, 1994

By S. Viswanathan, A. S. Sabau

"Dimensional changes between a pattern die and its corresponding investment casting part occur as a result of complex phenomena such as thermal expansion/contraction and hot deformation (elastic, plastic, and creep) during the processing of the pattern material (wax), mold material (shell) and solidifying alloy. Determining the pattern tooling dimensions is crucial to the dimensional control of the investment casting process. To date, computational methodologies have not been applied to the prediction of dimensional changes in investment castings.This paper deals with the evaluation of wax pattern dimensions, which is one important factor in determining pattern tooling dimensions in investment casting. Cerita 29-51, an industrial wax, is considered in this study. The wax pattern dimensions are determined by considering its thermo physical and thermomechanical properties, restraint of geometrical features by the metal die, and process parameters such as dwell time, platen temperature, injection pressure, and injection temperature.IntroductionThe investment casting process involves making a disposable wax pattern by injecting wax into a metal mold, building a ceramic shell mold around the wax pattern by the application of a series of ceramic coatings to the wax pattern, dewaxing the ceramic shell mold, and casting the alloy into the shell mold. Dimensional changes between the pattern tooling and its corresponding cast part occur as a result of thermal expansion, shrinkage, hot deformation, and creep of the pattern .material (wax), mold material (shell), and solidifying alloy during the processing [1]."

Jan 1, 2001

By Y. Ono

In lightweight metal processing such as aluminum (AI) and magnesium (Mg), metal cleanliness is a crucial process parameter for refining, part manufacturing and recycling in order to obtain high quality parts and products. In this paper, techniques for cleanliness evaluation of molten AI and Mg using ultrasonic probes with clad steel buffer rods having high signal-to-noise ratio (SNR) are presented. Due to the high SNR of the ultrasonic probes used, backscattered ultrasonic signals from inclusions, which may be oxide films and/or particles, in molten Mg and those from silicon carbide particles, having an average size of 50f.Ull, added in molten AI are successfully detected with reflection configurations of pulse-echo and/or pitch-catch modes at an ultrasonic frequency of 10 MHz. In addition, relative cleanliness evaluation of molten Al and Mg is demonstrated. In order to establish the procedure and to investigate the optimum system configurations for cleanliness evaluation of molten metals, particle flow simulation system using water and polyvinyl chloride (PVC) particles has been constructed. Counting the number and measuring the size distribution of the PVC particles, having an average diameter of 128um, suspended in water with the PVC volume concentrations of 5ppm and 10ppm are performed with ultrasonic pitch-catch mode. The counted numbers of particles by the presented method and system have good agreement with the calculated results with a count error of less than 10% or two counts. Based on the results obtained with water simulation experiments, the prototype system for cleanliness evaluation of molten Mg by counting and sizing inclusions has been developed. Keywords: Ultrasound, Clad buffer rod, Molten metal, Aluminum, Magnesium, Inclusion detection, Cleanliness measurement, Counting, Sizing

Jan 1, 2003

By Vincent Canaguier

Methane is increasingly considered as a promising reductant for metal oxides, including chromite. To assess the possibilities of such reduction route, the gas-solid reactions between Ar–CH4–H2 gas mixtures and synthetic chromites are studied between 950 and 1050 °C. The influence of Mg and Al additions on the reduction-caburization of (Fe,Mg)(Cr,Al)2O4 solid solution is investigated thermodynamically, structurally and kinetically. The product phases are examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). The reaction rate is derived from real-time exhaust gas measurements and post-reaction product analyses such as oxygen analysis. Kinetic models are proposed based on the product phase morphologies and confronted with the empirical data.

By Rolando Campos

Until 1970, the Caletones Smelter of CODELCO-CHILE, División El Teniente, operated under the conventional pyrometallurgical process used by most of copper smelters. The annual copper production varied around 165.000 tons. The failure in the commissioning of the "oxygen smelting" technology in Peirce- Smith converters (1970-1972), forced further introduction of transcendental changes in the Caletones smelter operating scheme. Implemented technological innovations were based on wide studies and research works performed by División El Teniente. This paper presents a summary of technological modifications introduced, their impact on production and energetic performances, and short and medium terms improvement plans.

Jan 1, 1993

By David Roha, Øyvind Mikkelsen

"Significant resources have been spent throughout the years in the investigation of production of aluminum by carbothermic reduction. Due to the technological challenges involved, the efforts have not yet resulted in a commercial process. An initiative to overcome issues that prevented previous attempts to succeed was taken by Alcoa through the Advanced Reactor Process. The research program has resulted in technical developments which have resolved many of the previous issues. The knowledge about the process has continuously improved through physical and computer modeling as well as by experimentation at various scales. The technical achievements together with improved process understanding have resulted in a reactor design able to continuously operate the process for several weeks at the time, with hundreds of kilograms of alloy in every tap.IntroductionThe Hall-Heroult process has since its invention in the late 19th century, been essentially the only process used for commercial production of primary aluminum. The process has so far proved to be superior to all potential process alternatives and has continuously been improved. Although the Hall-Heroult is a reliable process it also has challenges:"

Jan 1, 2012

By S. Eckert, G. Gerbeth, K. Timmel, B. Willers, T. Wondrak, N. Shevchenko, M. Röder

The quality of the produced steel in the continuous casting process is significantly governed by the melt flow in the mold. However, direct flow measurements in liquid metals are still rather scarce. In order to investigate these flow phenomena, three experimental facilities operating with low melting liquid metals were installed at Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The melt flow in the models is measured by the Ultrasonic Doppler Velocimetry (UDV) or the Contactless Inductive Flow Tomography (CIFT), multi-phase flows can be visualized by X-ray imaging. The obtained measurement results are primarily used for validation of numerical models. In this paper we will investigate the fluid flow in the mold and the behavior of the surface of the liquid metal using flow measurements by UDV and surface profile measurement by a laser scanner, respectively. Strong fluctuations and deviations of the free surface were observed in case of a static magnetic field

Jan 1, 2016

By Markus A. Reuter

In this paper various hybrid modelling architectures are proposed for the modelling and metallurgical control of pyrometallurgical reactors. Discussed are architectures in which data reconciliation is combined by thermochemical, neural net and dynamic modelling to improve the models. At the same time the data reconciliation models can act as soft-sensors for estimating unmeasurable data. Cases that are discussed are (i) the modelling of a submerged arc furnace for the production of thermal phosphorous, (ii) the processing of Sn-Pb-Zn flue dust (originating from secondary copper) in a hearth furnace, (iii) modelling of a steel converter, and (iv) dynamic modelling of a flash smelter.

Jan 1, 2001

By Jian Li, P. Liu, R. Zhang and J. Lo

In the past decades, focused ion beam (FIB) has evolved into a powerful microscope that provides capabilities that no other microscopes can offer. The combination of high-resolution imaging and stress-free ion beam cross sectioning provides valuable microstructure information both at the specimen surface and beneath. FIB techniques are also the preferred method to prepare site-specific transmission electron microscope (TEM) specimens. CanmetMATERIALS owns a world-class microscopy facility, where advanced microscopy work provides strong supports to research programs that cover a wide range of subject areas. This paper is aimed to provide a few practical examples of FIB applications in microstructure characterizations that include cross-sectioning and imaging, serial sectioning, and advanced TEM specimen preparation in materials research at CanmetMATERIALS.

Jan 1, 2015

By Amir Rehmat

The Institute of Gas Technology has developed a fluidized-bed process for recovering direct reduced iron from blast furnace flue dust a material currently considered to be a waste from the iron and steel industry. In the process, a portion of the carbon in the flue dust is combusted to supply energy for the endothermic reaction between carbon and steam. The reaction produces reducing gases comprised of carbon monoxide and hydrogen both of which react with iron oxides to produce reduced iron. Up to 95 percent of the iron oxides contained in the waste stream can be reduced to elemental iron. The vitiated reducing gases emanating from the process can be used as fuel in the plant. The yield of iron depends upon the quantity of iron oxide present in the flue dust and generally ranges from 20 to 30 percent of the waste stream. The investment cost estimated for a single processing train dedicated to one steel plant can be recovered in less than one year.

Jan 1, 1996

By E. N. Mounsey

The paper addresses the design of the Zhong Tiao Shan Company (ZTS) Houma Ausmelt Technology copper smelter in People's Republic of China. The smelter represents the third copper smelter development using Ausmelt Technology, the first large scale (35,000 tpy blister copper) and the first smelter to use the Ausmelt Technology smelting and converting process steps in separate TSL vessels in a continuously operated process. The project will be realised through the combined efforts of ZTS, Ausmelt and ENFI, the Beijing Non-Ferrous Engineering Institute who provided partial detail engineering services in China. Ausmelt will provide the technology licence, basic and detailed furnace engineering packages and additional technical services including cold commissioning support and hot commissioning supervision.

Jan 1, 1999

By T. C. -M. Cheng

Iron removal and disposal in zinc plants has imposed a major environmental challenge to the industry. Among the existing options of precipitating iron as jarosite, goethite, and hematite, the Hematite Process seems to be the best candidate for the future development of a waste-free technology, because of its potential of producing saleable iron oxide residues for feed in iron-steel making industry. Unfortunately, under the current practice of the Hematite Process, it is not possible to produce iron residues clean enough to meet the specifications of the said industry. In this paper, the practice of industrial hematite precipitation and the relevant technical literature are reviewed with the objective to identify the critical processing parameters which are responsible for the contamination of hematite, particularly with sulfur and zinc. The analysis is conducted from a crystallization theory standpoint with emphasis given to the role of supersaturation with respect to the cleanliness of hematite precipitates.

Jan 1, 1997

By Zhenbo Zhao

The processes and equipment for INLRFH (Isothermal Normalizing by Utilizing the Residual Forged Heat) of alloy carburizing steel products are presented. It is shown that four key parameters: namely (I) cooling rate before isothermal normalizing, (IT) the lowest cooling temperature before isothermal normalizing, (111) isothermal normalizing temperature and (IV) isothermal normalizing time, should be controlled. The prediction and calculation of these parameters can be achieved on the basis of components treated and the technical requirements of the steel parts by an on-line expert system. The cost-reductions due to the energy savings resulting from implementing this system for automotive parts heat-treatment are most promising.

Jan 1, 1999

By Denise C. R. Espinosa

Rechargeable lithium batteries are one of the most promISIng technology in battery development. Although Li ion batteries have been used as an alternative to the more polluting and less performing Ni-Cd batteries, Li ion batteries have limited life and their disposal is uncertain. It is imperative that valuables from wastes, such as lithium, should be recovered. The main objective of the present work was to characterize secondary lithium batteries for cellular phones. This was done using unit operations of mining processing, x-ray diffraction (XRD), chemical analyses and the rmogravimetric analysis (TG). The unit operations were hammer mill grinding, knife mill grinding, size separation and magnetic separation. After the hammer grinding process, the plastic cases were almost intact, however, they have released the cylindrical lithium batteries themselves and these parts correspond to 70% of the total battery weight.

Jan 1, 2001

By Suswnu Makino

Sumitomo Metal Mining developed a new nickel refining process ( Matte Chlorine Leach Electrowinning process) based on chlorine leach and electrowinning technologies. After the pilot plant study, the commercial plant with design capacity of 24,000 tonnes per year was constructed and has been successfully operated since August, 1992. During the practice of the past three years, great deals of improvement have been achieved. Through these operations the MCLE process has been demonstrated to be one of the most superior processes in the world with nickel recovery, productivity, cathode quality and working environment. Today the refinery product capacity is increased to 30,000 tonnes per year. This paper describes the equipments and operation of the Sumitomo MCLE process.

Jan 1, 1996

By William Petruk

The mineralogy of the primary and oxidized ores from the Malanjkhand porphyry copper deposit in India was studied to determine ore characteristics that affect metallurgy, and to assess applicable processes for recovering the copper. Three mineral assemblages were found. One occurs in primary ore, another in moderately oxidized ore, and a thir:d in intensely oxidized ore. Chalcopyrite, the main mineral in the primary ore, is relatively coarse-grained, with grain size increasing as the ore grade increases. High chalcopyrite liberations should be achieved at a relatively coarse grind, and good chalcopyrite recoveries should be obtained. The chalcopyrite, however, tarnishes readily and oXidizes to chalcocite in a relatively short time (several months). The presence of both the tarnished chalcopyrite and chalcocite may affect chalcopyrite flotation and reduce copper recoveries, The moderately oxidized ore occurs in an oxidized cap immediately above the primary ore, and stockpiled primary ore alters quickly to a moderately oxidized ore. Chalcocite is a major copper-bearing mineral in moderately OXidized ore. The concentrator processing this ore should be capable of handling a chalcocite-rich ore. The intensely OXidized ore contains a wide variety of acid-soluble copper-bearing minerals. Leaching may be required to recover the copper from them.

Jan 1, 1987

By D. A. Horne, V. R. Daiga

Certain steel mill wastes contain significant amounts of zinc oxide due to the use of galvanized scrap during the steel making process. Typically electric arc furnace (EAF), and basic oxygen process (BOP) flue dusts contain 20 to 30% zinc oxide and 40 to 50% iron oxides, along with smaller quantities of lead and cadmium. These materials can be recovered from the flue dusts by using a proven rotary hearth furnace (RHF) process. By-products of the recycling operation include a crude zinc oxide fume, which is captured in a baghouse filtering system, and sponge iron that may be recycled into the steel making operation. Crude zinc oxide properties plus the operating experience from two commercial RHF installations utilizing MR&E's DRyIron™ Process will be presented.

Jan 1, 2000

By J. M. Skeaff

As much as 100% of the gold and 67% of the silver in a sulphur-bearing hydrometallurgical leach residue have been transferred to copper metal at copper smelting temperatures by dissolving the partially calcined residue in an iron-bearing slag maintained in equilibrium with the liquid copper metal and matte phases. The precious metals can then be recovered by conventional refining techniques. Copper can be recycled at least four times without any detrimental effects on gold and silver transfers and recoveries. Apparent copper recovery in the .process can be over 100% because of the copper content of the residue. Based on slag analys.es, the overal1 recovery of gold in the copper metal and matte phases varies from 94% to 100% under all conditions investigated. On the? same basis, silver recovery varies .from 9S% ?to 99% under optimum conditions, but is only 4S% to 73% under other, less attractive conditions. Unaccounted for silver losses of' about 30% make it difficult to determine the major factors affecting ?silver transfer and recovery. A method for implementing the technology on a commercial scale at a Canadian copper/zinc smelter has been proposed. A preliminary economic assessment and comparison of the proposed pyrometallurgical process with conventional cyanidation indicates that either process is economically attractive for recovering gold and silver from leach residues. Although the capital costs are higher, the pyrometallurgical process is simpler, has higher recoveries, lower operating costs and no .potential environmental problems related to cyanide disposal.

Jan 1, 1989

By Sebastião Ribeiro, Leonardo Carneiro Sardinha, Alline Sardinha Cordeiro Morais, Carlos Maurício Fontes Vieira, Sergio Neves Monteiro

The glass tube of spent fluorescent lamps is contaminated with mercury, which might be a serious hazard in the case of conventional recycling by melting with other glasses. A possible solution could be its incorporation into a clay body to fabricate common fired ceramics such as bricks and tiles. The objective of this work is to characterize a type of fluorescent lamp glass waste to be incorporated into a clayey ceramic. The characterization was performed in terms of wettability tests to evaluate the interaction between the surface of the clayey ceramic and glass waste as a function of the firing temperature. The results showed that the contact angle decreased with increasing temperature, reaching a value of 79°, at a temperature of 1100°C, but not sufficient to completely wet the ceramic. However, compatible chemical composition and reduction of porosity by the flow of soft glass waste between the clay particles favor the consolidation of the ceramics structure above 900°C.

Jan 1, 2015

By Jilai Xue, Jun Zhu, GermainKouma Ndong, Luxing Feng

High-temperature corrosion behaviors of Fe-Ni-Cr alloy as inert anodes for aluminum electrolysis have been studied. The effect of anodic overpotential on layer growth of anodic surface is specially considered. The corrosion layers on the anodes tested were analyzed using XRD and SEM-EDS to provide a fundamental understanding of the layers growth at metallic anode surface. The dissolution of the scale layers on the metal anode occurred with low overpotential, while AlxM3-xO4 spinel phase within the scale layers was found with an increased overpotential. A mixture of multiple MyO layers existed on the anode substrate. The results may be useful for understanding and controlling the corrosion behaviors of Fe-Ni-Cr anode for potential application in aluminum electrolysis.

Jan 1, 2015