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By Andrey V. Tarasov

To carry out a physicochemical substantiation of a transition to ?soft? modes of reduction of calcine obtained by desulfurizing roasting of nickel concentrate produced as a result of copper-nickel converter matte separation in a nickel anode production circuit, an analysis has been conducted of the macrokinetic behavior of actual calcine samples in the presence of gaseous H2-CO mixtures and solid reductant additives. Within a temperature range of 900°C to 1100°C the main regularities typical of the calcine reduction process with individual gases (H2, CO) also take place when using a gaseous mixture. Under the conditions of low-temperature (900°C to 1000°C) nickel oxide reduction with products of fuel oil conversion in the presence of coke, the role of the latter is insignificant from the technological viewpoint. As a result of the present investigations, we have obtained analytical expressions of macrokinetic parameters of the reaction interaction within the [NiO] calcine-H2-CO-C-CO2-H2O-O2-N2 system.

Jan 1, 2005

By M. D. Strachan

Technical & Procurement Services Limited (TECHPRO) in Ashford, Kent, UK, have been appointed as Project Managers for the major rehabilitation of the Copper Smelting complex of Nkana Division, Zambia Consolidated Copper Mines Limited, (ZCCM) Zambia. In outline, the overall scope covers three main areas: a) Transfer and implementation of new technology into Zambia for the production of primary copper. b) Replacement of gas collection and gas treatment circuits to guarantee high quality feed to the acid plants. c) Completion of a number of minor projects in the copper smelter and associated utility plants to complement changes in the primary smelting technique. This paper describes the Project Management methodology and style used by TECHPRO to tackle typical problems that arise in retrofit projects of this type. Reference is made specific aspects of the smelter projects to illustrate solutions to the problems. The subjects. addressed highlight the complexities not only of having a -Client 5,000 miles from the Project Office, but also the difficulty of co-ordinating and controlling the performance of min sub-contractors who are also geographically distant.

Jan 1, 1991

By A. S. Usrnani

Due to both turbulence and the highly variable geometry of castings, a realistic numerical simulation of the metal flow is prohibitvely expensive with current technology. However, when the chief purpose is to achieve realistic thermal fields a precise How simulation is not necessarily required. In this paper we assume a laminar flow regime and obtain the flow field by solving the incompressible Navier-Stokes Equations using a velocity-pressure segregated semi-implicit finite element method. The free metal surface is predicted by advecting a pseudo-concentration function via the computed How field. This involves an explicit finite element solution of a pure advection equation. The thermal field is calculated by solving the convective-diffusive energy equation by an explicit finite element method using the computed flow field and the location of the free surface. All the advection terms are discretized using a Taylor-Galerkin method. The interface between the metal and mould is modelled using special interface elements. The model is demonstrated by solving practical example problems. The results show that a sharp thermal front is maintained during the course of filling without excessive diffusion. The heat diffusion in the mould can be controlled by varying the metal mould heat transfer coefficient.

Jan 1, 1994

By Kim Fagerlund

Boliden Harjavalta Oy operates a copper smelter in Finland, which is based on flash smelting together with Peirce-Smith converting of copper matte. This paper reviews a case study when a high arsenic feed mixture was successfully eliminated in order to guarantee the anode quality. Based on theoretical and practical knowledge in slag chemistry at Outokumpu Research, the CaO-fluxing practice was introduced. Description of a thermodynamic simulation using MTDATA and implementation of the results into converting practice is given. Results showed that the impurity fluctuations in raw materials could be effectively controlled by efficient utilization of different slag chemistry.

Jan 1, 2005

By Zhongning Shi, Ramana G. Reddy, Min Li, Zhaowen Wang

Electrodeposition of cobalt from cobalt tetrafluoroborate (Co(BF4)2) was investigated using 1- butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquid. The experiments were conducted at 353 K. Chronoamperometry experiments confirm that the electrodeposition of cobalt on tungsten electrode proceeds via three-dimensional instantaneous nucleation with diffusion-controlled growth process. The average diffusion coefficient of Co(II) was found to be 7.5 × 10-8 cm2s-1 at 353 K, which is in good agreement with the estimated value from cyclic voltammetry. The electrochemical deposit was characterized using SEM-EDS and XRD methods. The SEM image shows formation of a dense and compact deposit at - 0.75 V. The EDS and XRD analysis confirm that the obtained deposit is pure cobalt metal.

Jan 1, 2015

By Ji-He Wei

Keywords: stainless steel, AOD refining, side and top combined blowing, mixing characteristics, water modeling The fluid mixing characteristics in the bath during the side and top combined blowing AOD (argon-oxygen decarburization) refining process of stainless steel have preliminarily been investigated on a water model unit of a 120 t AOD converter. The geometric similarity ratio between the model and its prototype (including the side tuyeres and the top lances) was 1:4. On the basis of the theoretical calculations for the parameters of the gas streams in the side tuyeres and the top lances, the gas blowing rates used for the model have more reasonably been determined. The influence of the tuyere number and position arrangement, and the gas flow rates for side and top blowing on the characteristics has been examined. The results demonstrated that the liquid in the bath underwent vigorous circulatory motion during gas blowing, without obvious dead zone in the bath, resulting in a well mixing effectiveness. The gas flow rate of the main tuyere had a governing role on the characteristics, a suitable increase in the gas flow rate of the subtuyere could improve mixing efficiency, and the gas jet from top lance could make the mixing time prolong. Corresponding to the oxygen top blowing rate specified by the technology, a roughly equivalent and good mixing effectiveness could be reached by using six side tuyeres with an angle of 27 degrees between each tuyere, and five side tuyeres with an angular separation of 22.5 or 27 degrees between each tuyere. The relationships of the mixing time with the gas blowing rates of main-tuyeres and sub-tuyeres and top lance, the angle between each tuyere, and the tuyere number have been obtained.

Jan 1, 2005

By Ryan Walton

The Flash Converting Furnace at Kennecott Utah Copper converted over 465kmt of high-grade matte in 2002 but was restricted due to low matte production to 395kmt in 2003. This paper presents updated operational performance data and describes improvements implemented since the mid 2001 rebuild. Matte burner feed distribution, silica and arsenic impacts on settler lime-based slag operability, blister laundering, uptake/boiler accretion control, and dust sulfation will be discussed, as well as current development requirements dictated by operational imperatives and furnace modification plans.

Jan 1, 2005

By Scott A. Shuey

Keywords: E-Waste, Pyrometallurgy Many might think addressing the issue of e-waste is a new area of study. Electronics disposal has been discussed in some circles for at least the past 25 years. The recycling of electronic waste (e-waste) tends to be a rather complex undertaking when considering the intimate bonding of materials in the average printed circuit board. The development of a recycling process is further complicated when considering the wide variety of products being generated under the heading of ?electronics.? Focusing only on the primary constituents (polymers, Cu, Al, Fe, etc.) tends to lead one to fairly simple flowsheets. Ignoring trace elements, and the various halide species generated, will lead process engineers down a development path that is sure to cause material handling issues. Researchers at Colorado School of Mines are modeling the complex chemistry that exists within the body of e-waste?comprising 39 of the known elements. An understanding of the systems thermodynamic behavior will result in the development of a more robust, long-term process for the recovery of valuable materials from the e-waste stream.

Jan 1, 2005

By L. R. Verney

About 75% of the market economy countries's supply of cobalt is produced in Central Africa by Zafre and Zambia. Zafre alone accounts for more than 55% and has the resources and capacity to increase output significantly at any time so its dominant position is unlikely to be challenged in the foreseeable future. Other producers from domestic resources are Canada, Australia and South Africa; and Cuba, probably the most important producer outside of the Market Economy countries. Belgium, Norway, France, Japan and Finland produce cobalt from imported materials. While there are "cobalt ores", inMorocco, USA, Canada and the USSR, the mineralisation is complex and cobalt extraction is costly. In ZaPre and Zambia cobalt is a by-product of copper; in Canada, Australia, France, and Cuba it is a by-product of nickel; and in South Africa it is a by-product from the production of Platinum Group Metals. Thus the levels of cobalt production are inevitably related to the production of other primary metals. While some cobalt is produced by predominantly pyrometallurgical methods most of the world's cobalt is produced hydrometallurgically. The existence of large hydro-electric power plants and the mineralogy of the copper and cobalt concentrates encouraged research and development in Zafre of the recovery of copper and cobalt by electrowinning from sulfate solutions; much pioneering work was carried out, which lead to construction of the two largest copperlcobalt hydrometallurgical plants in the world, at Shituru and Luilu. Similar systems were adopted in Zambia. In Canada high pressure hydrometallurgical processes based on the sulfate system were developed and adopted in Australia, the Philippines, Finland and South Africa. Meanwhile developments in chloride hydrometallurgical extraction of nickel and cobalt lead to its use in the extraction of cobalt in Norway, France and Japan.

Jan 1, 1988

By Melissa L. Trapani

Keywords: Copper, Taphole, Flow Instability. ?Blister spitting? is a flow irregularity where the molten blister copper stream ? or part thereof ? sprays from the taphole exit rather than following a regular flow profile to the collection box. As well as being a general ?housekeeping? issue, the unpredictable nature of the flow is a threat to operator safety. Also, the aggressive flow pattern may contribute to the mechanical wear of the taphole refractory, compromising the integrity of the taphole. This paper brings together a collection of first-hand observations and reports from process personnel, and suggests some theories as to the causes of blister spitting.

Jan 1, 2005

By Pengfu Tan

Converter slag chemistry control has played an important role in optimizing converter operations. A thermodynamic model of copper P-S converter has been developed to predict the behavior of magnetite in the converter slag. Predictions of bath temperature, slag and matte compositions, and magnetite content in the slag have been validated by industrial data. The effects of fluxing strategy, returns and skim charges, oxygen enrichment, and temperature on the magnetite formation in the slag have been predicted and discussed. Some improvements of the industrial operations have been presented.

Jan 1, 2005

By Asmo Vartiainen

Background of Direct-to-Blister Flash Smelting is discussed; especially slag chemistry relating to copper solubility, slag fluidity and impurity behavior. In December, 2000, Mini-pilot Flash Smelting test runs were carried out at Outokumpu Research Oy to produce blister copper from Chilean concentrate and white metal and from a mixture of them. Tested slag types were iron silicate slag, ferrous calcium silicate slag and calcium ferrite slag with different slag compositions and different concentrate/white metal ratios. The test runs were successful. The fluxing effect of copper oxide was clearly demonstrated and ferrous calcium silicate slags remained fluid on a very wide liquidus range. The distribution of arsenic between ferrous calcium silicate slag and blister copper is much higher than between iron silicate slag and blister copper. This successful test run with the new slag type offer new possibilities in Direct-to-Blister process design.

Jan 1, 2003

By W. -D. Schneider, B. Schwab

Like all metals, zinc can be recycled theoretically without end. To demonstrate environmentally friendly use of zinc, it is necessary to increase the recycling rate. In this regard, the Imperial Smelting Process developed in the forties and fifties in the United Kingdom has become more and more important. This unique process combined with a sinter plant, hot briquetting, and direct injection through the ISP furnace tuyeres offers ideal possibilities to recycle all kinds of zinc and lead bearing materials. Possible secondary materials include Electric Arc Furnace (EAF) dust, zinc-containing sludges and even zinc/carbon batteries. This high temperature process also destroys all organic materials, like dioxin, and can be seen as a sink for many harmful substances.

Jan 1, 2000

By John B. Cocanour

The U.S. Bureau of Mines (USBM) has developed a laboratory-scale on-line analysis and process control system for a decopperization electrolytic circuit. This system is software driven, running on a 486DX-33 personal computer (PC) utilizing a portable energy- dispersive x-ray fluorescence (XRF) spectrometer as the sample analyzer. The XRF copper reading obtained was used as the control variable through an RS-232 serial interface to the PC for software-based control of feed flowrates. When the copper concentration in the electrolytic cell (as measured by the XRF) deviated from the set point, the feed flowrate to the cell was automatically altered using software-based proportional-integral-differential (PID) computer control to yield the desired copper concentration at the electrolytic cell outlet.

Jan 1, 1994

By Bryce Clark

Cobalts history from the 14th Century is outlined, with a look at its various sources over that period. The present sources and quantities are given, when in 1994 it is an equal co-product of copper in Africa and nickel elsewhere (Canada, Australia, Russia). Future trends in this scene are also examined. The final section deals with cobalts uses in superalloys, magnets, colours, electronics, chemicals, and examines trends in its markets. Supply and demand in co-product cobalt are shown, based on the latest production figures.

Jan 1, 1995

By Tsunehisa Nishimura

Stable operation of the blast furnace needs adequate control of the lower part. To clarify the behavior of the lower part of the blast furnace with accurate consideration of the property of slag and its flow characteristic, a new mathematical model has been developed. Using this model, the effects of the change of operational conditions on the behavior of the lower part of the blast furnace were studied. Further, means to control of the lower part of the blast furnace, especially effective means to maintain adequate temperature, were discussed. And desirable slag property and composition, especially the method to control FeO concentration dripping from the bottom of the cohesive zone to avoid a decrease in temperature of the lower part of the blast furnace was estimated.

Jan 1, 2006

By Kazuya Koyama

We are studying the hydrometallurgical recycling process of indium from an Indium-Tin-Oxide(ITO) target. For this process, it is necessary to remove Sn(IV) ions from the aqueous hydrochloric acid solutions containing In(III). In this study, the removal of Sn(IV) ions by a potentiostatic electrolysis method was examined. The polarization measurements and potentiostatic electrolyses were carried out under a nitrogen atmosphere. In the Sn(IV) solution, current begins to rise at the cathode potential of -0.26 V vs. SHE, and increases with a reduction in the cathode potential. In the In(III) solution, current begins to rise at a cathode potential of -0.43 V vs. SHE. Metallic tin was electrodeposited without indium electrodeposition at the cathode potentials of -0.30 and -0.40V vs. SHE. More than 98% of the Sn(IV) was removed at the cathode potential of -0.40 V after the electrolysis for 3hrs. Both tin and indium were electrodeposited at the cathode potential of -0.50V vs. SHE.

Jan 1, 2006

By Yuzhe Zhang, Matthew Andriese, Jiann-Yang Hwang, Guanghui Li, Zhiwei Peng, Tao Jiang

The microwave power absorption characteristics of iron oxides, including Fe2O3, Fe3O4 and Fe0.925O, have been studied by determining dielectric loss and magnetic loss distributions in 0.05-m-thick oxide slabs irradiated with 1.2-kW, 2.45-GHz microwaves. The results reveal that the dielectric loss is the main factor contributing to microwave absorption in Fe2O3 and Fe0.925O, while the magnetic loss dominates the power absorption in Fe3O4 below its Curie point. Uneven power distributions are observed in the slabs and this phenomenon becomes even worse at high temperatures at which the permittivity increases significantly. Quantification of power absorption in the oxides is of great importance for efficient and uniform microwave heating

Jan 1, 2015

By Onder Guney, Erdem Demirkesenm

"In this study, the crystallization behavior and thermal expansion coefficient of a lithium disilicate (LS2) based glass-ceramic derived from SiO2-Li02-AhO3-K2O-ZrO2 system was investigated by using x-ray diffraction (XRD), high temperature x-ray diffraction (HTXRD), differential thermal analysis (DTA) and dilatometer techniques. Analytical reagent grade chemicals were chosen as raw materials for preparing glass batches. Nucleation and crystal growth heat treatments were planned according to DTA results. The amounts of the amorphous and crystalline phases developed during the heat treatments were determined by quantitative XRD. XRD results of crystallized samples showed simultaneous formation of lithium silicate (LS) and quartz in the early stage of the crystallization followed by formation of lithium disilicate (LS2) at higher temperatures. The thermal expansion coefficients of glassceramics were also measured depending on the applied heat treatments.IntroductionSignificant developments occurred in all ceramic materials provide the fabrication of high quality dental implants [1]. Glass ceramic based dental restorations like dental inlays, crowns, bridges and veneers are becoming increasingly popular with their reliable and durable performance [2,3]. In addition to their advanced functional properties, glass ceramic implants especially lithium disilicate glass ceramics also face the esthetics expectations of patients and dentists and in this way they are starting to take the place of metal based restorations today [1,3,4,5]. Lithium disilicate glass-ceramics derived from multicomponent glass systems have some superior mechanical and optical properties comparable to natural teeth [ 6]. In restorative dentistry, mechanical characteristics of biomaterials play very crucial role in order to resist the masticatory forces occurred during biting and chewing [7] According to three point bending test results of Roland, flexural strength of the lithium disilicate glass-ceramics were 400±40 MPa and their fracture toughness (K1c) are approximately 3,3 MPa m112 [2,6]. In addition to high mechanical strength, aesthetic appearance is another important prerequisite as material for dental restorative applications. Translucency and light transmission of the LS2 glass ceramics mimic enamel. Moreover, opacity of the material can also be adjusted depending on the restoration types [2,6, 7]. These superior properties of the LS2 glass ceramics are directly related with chemical composition of the base glasses and controlled crystallization heat treatments [ 4, 7]. The aim of the present work is to determine the effect of heat treatment schedules on the crystallization behavior and thermal expansion of the LS2 glass-ceramics."

Jan 1, 2011

By J. Antrekowitsch

Keywords: residues, fluorides, chlorides, zinc, steel mill dust The recyclability of various nonferrous metal wastes often suffers from a relatively high fluorine and chlorine content. Both are inserted in most cases by the use of plastic contaminated scrap and a wide variety of different coatings. These halogens lead to poor product qualities and off gas contamination. Especially the history of zinc recovery from steel mill dusts shows, that the today common hydrometallurgical options are on their limit and therefore are not sufficient in most cases. This thermochemical study should give more information about different pyrometallurgical options, that offer both a chlorine and fluorine reduction and efficient zinc recovery, preferably in one process step. Selective evaporation in different atmospheres and conversion with the use of hydrogen are the main parts in this study. The results combined with the relatively small information available from literature should provide a basis for further investigations in this field.

Jan 1, 2005