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By Larry M. Southwick

Pneumatic converting (Bessemerizing) of iron revolutionized the steel industry. Bessemerizing of copper (conversion of copper sulfide matte to copper metal) was proposed at almost the same time, but it was slow in being accepted. The differences between iron and copper converting were great and technical problems were substantial. It took 25 years for the process to become viable and another 25 years before a truly economical solution was found. A major economical and productivity problem was the short life for converter refractory linings. The first converters had acid (silica) linings, which were quickly consumed since silica was a flux for the process. Converters had to be relined at least once per day, a laboriously expensive manual process with only the most rudimentary mechanical aids available to assist. The industry was revolutionized almost overnight when finally a viable basic (magnesite) lining was developed. This lasted 100's of days versus less than one, leading to converters that were easier to operate and which handled larger charges. This change occurred after W.H. Peirce and E.A.C. Smith, with support from the Guggenheim interests, successfully operated a basic lined converter in a copper refinery in Baltimore. While Peirce and Smith are generally given credit for the development and explosive acceptance of this idea, a Pittsburgh industrialist, Ralph M. Baggaley, working in an independent smelter in Butte, Montana, successfully built and operated a basic lined converter four years before they did. In fact, the early support for Peirce and Smith likely occurred because Guggenheim's staff were encouraged after thoroughly examining Baggaley on his earlier successes. The questions of technology primacy between Baggaley and Peirce/Smith are ironically similar to those between Wm. Kelly and Bessemer in converting iron to steel. This paper will review what Baggaley (and other early researchers) accomplished, examine why he (or they) did not receive credit equal to Peirce and Smith and explore what his (their) place should be in the development of successful basic linings. More suspects than a Victorian Whodunit.

Jan 1, 1999

By A. F. Kaczmarek

Cerro Negro is an undeveloped ore body located at the Cerro Verde mine near Arequipa, Peru. The mineable reserve contains 70 Mt of oxide ore grading 0.532% copper. Mineralization is hosted in three distinct rock types: tourmaline breccia, crackle breccia and granodiorite. Rock type effects copper recovery and acid consumption. The paper describes Cyprus' testwork philosophy and the resulting four-phase metallurgical program used to define the commercial leaching parameters. Copper recovery and acid consumption were monitored as functions of crush size, heap height, irrigation rate and acidulation conditions. Single lift, on-off and permanent multi-lift heaps were considered. Leach cycle times were based on incremental copper extraction and acid consumption rates, with added constraints imposed by operational requirements. The optimum leach system involves an on-off pad using tertiary crushed ore acidulated with 20 kg/t acid and stacked to a height of 6.5 m. The active leach cycle is 82 days at an irrigation rate of 0.26 l/min/m2. Under these conditions copper recovery is expected to average 81% over the life of the mine.

Jan 1, 1999

By N. Krishna

The utilization of Electrochemical Impedance Spectroscopy (EIS) in conjunction with Atomic Force Microscopy (AFM) is a powerful surface characterization technique to study the role of sulfur formation during acidic oxidation of chalcopyrite. It has been established that the chalcopyrite dissolution kinetics is controlled by the formation of passive sulfur layer during leaching. The objective of the study was to characterize the intermediate sulfur layer formation at different oxidation conditions in acidic solution. The chalcopyrite samples were subjected to anodic oxidation and the oxidation process was analyzed using impedance spectroscopy. The sulfur growth on the chalcopyrite surface during oxidation was further analyzed using Atomic Force Microscope for sulfur roughness and grain size, peak height and sulfur growth.

Jan 1, 1999

By Osarnu Inoue

In Mitsubishi Continuous Copper Smelting and Converting Process, smelting, slag-matte separation and matte converting are continuously carried out in series in three furnaces connected by launders. As a result of this operational configuration of the furnaces, influence of the change in operating condition in upper stream, such as variation of feeds in the smelting furnace, propagates to down stream with some delay. In order to achieve stabler operation, process control algorithm based on the dynamic characteristics of each furnace would be very effective. In this study, the dynamic process simulation model was developed for the smelting furnace. The model consists of two mathematical modules, i.e. the thermodynamic module and the mixing module. The calculation results using operating data obtained at Naoshima Smelter showed good agreement with the actually observed change in temperature, composition and flow rate of matte and slag at the outlet of the furnace. In addition, operation parameters such as reaction efficiency of oxygen and coal, dead volume of melts were estimated.

Jan 1, 1999

By S. Motoiu

Data acquisition is widely used for controlling flash smelting furnaces. A Romanian smelter from which a large amount of data can be collected uses such a technique. A computer program was developed for interpretation of the data. Inputs to the program are the process data files. Abnormal data are identified using standard statistical techniques; they can be edited if necessary. The following methods can be used for the analysis: linear correlation (single or multiple), polynomial correlation or comparison of two average values. Time variation graphs and histograms can be displayed. The random balance method was used for determination of significant parameters influencing the process performance. Not all process parameters are recorded, and some of them are not even measured. The software can compute some of these parameters such as: air flow rate required and the oxygen content of the gas: exiting the reaction tower. The software was used for the interpretation of a large amount of process data. The analysis showed that the process did not operate properly at some times.

Jan 1, 1999

By L. A. Barta

A new process for the leaching of chalcopyrite concentrates has been developed and tested in miniplant campaigns and locked cycle testwork carried out between 1996 and 1999. The process involves pressure leaching in a sulphuric acid solution, e.g. raffinate from copper solvent extraction. Iron in the feeds is precipitated predominantly as hematite in the autoclave, simultaneously with copper extraction. Gold and silver in the pressure leach residue are recoverable by conventional cyanidation, following flotation to remove elemental sulphur by-product. The results of recent miniplant tests and batch locked cycle tests are provided.

Jan 1, 1999

By Jonathan M. Berkoe

Design engineers and metallurgists have long recognized the need for better methods to calculate a wide range of fluid dynamic effects in smelters and hydro- metallurgical facilities. Examples can range from the capture of fume in the secondary hoods of a copper converter, to controlling the thermal effects of heat transfer resulting from metal and slag flows within a furnace. With the advent of relatively low-cost, high- speed computers and user-friendly, commercially available computerized fluid dynamic (CFD) programs, these calculations can now be made. Use of CFD increased the understanding of both hot gas and molten flows in smelter facilities and has already led to design improvements in converter fume control hoods as well as improved management of heat transfer in electric furnaces. This paper will present two representative CFD applications to metals industry facilities. To date, Bechtel has implemented CFD results on four continents.

Jan 1, 1999

By M. M. Salari Rad

An investigation of gold distribution in the mill products of Sar Cheshmeh beneficiation plant demonstrates that on average 44% of the gold is routinely recovered as a by-product in the copper concentrate, and the remaining is lost to the tailing. In order to evaluate the causes of gold losses, the distribution and mode of gold occurrence in the Sar Cheshmeh ore and mill products were studied. Searching for gold within samples and within individual grains of sulphide minerals was carried out by SEM in the backscattered electron mode and SIMS, respectively. The mineralogical distribution of gold revealed by microbeam techniques were combined with the results of relevant metallurgical experiments including, sizing, heavy liquid separation, and diagnostic leaching tests, and the nature and location of gold in the ore and mill products were determined. The combined results of the experimental approaches pursued suggest that while there are some gold in solid solution and/or -colloidal size within sulphides of the Sar Cheshmeh ores, "visible" gold is the principal form of gold occurrence at Sar Cheshmeh.

Jan 1, 1999

By E. A. Trillo, L. E. Murr, R. D. Flores, J. C. McClure, B. M. Nowak

Complex vortex and swirl-like solid-state flow phenomena have been observed in the residual microstructures characterizing the friction-stir welding (FSW) of copper to 6061 aluminum; 2024 aluminum to 6061aluminum,2024 aluminum to 1100 aluminum, 2024 aluminum to 7039 aluminum and 2024 aluminum to 2195 aluminum. These flow phenomena are characterized by intercalation lamellae composed of dynamically recrystallized grain structures of the dissimilar metals which provide a super-plastic-like mechanism for the FSW flow in the solid state; there is no melting and temperatures at the weld center do not exceed about 0.8 TM (where TM is the absolute melting temperature (K)). In experiments to be described and illustrated, optical or light metallography (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques are utilized in examining residual FSW microstructures corresponding to tool rotation (stirring) speeds ranging from 400 to 1200 rpm, and traverse (or actual welding) speeds of 1 to 2 mrn/s.

Jan 1, 1999

By Li Cheng

The SKS copper smelting process was jointly developed by Shuikoushan Mining Corp. and ENFI (Beijing Central Engineering and Research Institute for Non-ferrous Metallurgical Industries) in China. It is a new bath copper concentrate smelting process with oxygen enriched air. The pilot plant testwork was completed successfully in 1993. SKS has demonstrated to be an advanced bottom blown smelting process. This technology got the First Class Prize of Scientific and Technological Progress awarded by CNNC (China National Non-ferrous Metal Industry Corp.) in 1994. The SKS process has significant capital and operating cost advantages. Its environmental and industrial safety and hygiene performance represents a substantial improvement when compared to conventional technologies. The technology has generated great interest in the Chinese metallurgical industry. Feasibility studies and basic designs have been carried out to incorporate in retrofit and green field smelter projects in China and abroad. This paper describes the history of the pilot plant operating data (50 tonnes dry feed/day), and discusses the features of the SKS technology, its application and possible future trends.

Jan 1, 1999

By Pertti Pekkala

Outokumpu has 25 years of experience in the SX area. The development of the solvent extraction plants responds to an ever increasing demand for lower operational costs wd for adaptability to process disturbances with minimized risks. In this paper the features of the VSF ("Vertical Smooth Flow") SX technology are described, such as the separated pumping and mixing, the homogenous gentle mixing, the droplet coalescence and the ultra pure settling. A major advantage of the mixing technology is the high stage efficiency of above 99 per cent. The connection between this and some features of the settler front section is clarified. The present design of VSF plants is based on experience of existing operations at, for example, Zaldivar, Radomiro, Morenci, Kokkola and Harjavalta. These production plants cover a unit capacity range of 60 to 3,600 m3/h expressed as a total flow. It is evident that there are no restrictive factors to increase the total flow up to 5,000-6,000 m3/h by introducing the VSF technology. The copper SX technology has a long history reflecting many individual features of the separate copper SX plants. Still it is necessary to verify all actual running parameters by pilot tests taking into account impurities, chemicals used etc. The design of SX plants is not only about the delivery of equipment but also a process concept, and it is best tailor-made and adapted to specific local requirements.

Jan 1, 1999

By Jörn E. Fischer

Cracks were observed at the top of spray formed billets for some alloys. In this paper the effect of process parameters on crack probability is discussed. After the spray run the thermal conditions at the top of the billet change rapidly. A hot spot with melt residue] can occur inside the billet and shrinkage will be suppressed due to the solidified surface of the billet. In this situation hot cracks can be initialized. The temperature history of the billet during and after the spray run is calculated. The temperature difference between core and outside diameter of the billet is taken as indicator for hot crack probability. The effect of different process parameters on the hot crack probability is discussed. The results lead to a better understanding of the process. The calculations are taken as a tool to find process parameters in order to reduce or avoid hot cracks in spray formed billets.

Jan 1, 1999

By Volker Uhlenwinkel

The design of a free fall atomizer as well as the process parameters affect the particle mass flux distribution in the spray cone. The mass flux distribution is important in spray forming because of its influence on the deposit shape and enthalpy input into the deposit. In this article the effect of different process parameters on the mass flux distribution is shown. Furthermore, different melts were atomized with the same atomizer. An empirical correlation will be introduced to predict the mass flux in the spray cone. This correlation will be compared with experimental results.

Jan 1, 1999

By J. R. Addison

Commissioned in September 1987, the Phelps Dodge Morenci, Inc. (PDMI) Central Electrowinning (EW) Tankhouse bas undergone two major expansions in its eleven-year history. A third tankhouse renovation, which began in November 1998, entails complete conversion of the 548-cell facility from a copper starter sheet based operation to Mt. Isa Process stainless steel mother blank technology. This paper outlines the operating history of the Central EW Tankhouse and reviews the conversion process, the rationale that led PDMI to undertake this project, and describes various design optimizations which have been implemented during the conversion.

Jan 1, 1999

By G. A. Eltringham, A. F. Sarofim, A. A. Shook, M. P. Heap, B. R. Adams, K. A. Davis

This paper discusses the use of a reacting CFD model to determine chalcopyrite kinetics in a drop tube furnace and to predict the reaction of a chalcopyrite concentrate in the reaction shaft of an industrial smelter. Reacting CFD codes can be applied to determine the consequences of the interaction of gas with particles and therefore improve the ability to derive kinetic parameters that take into account the different temperature and oxidation histories that different particles will see. This paper describes the application of such a model to derive improved kinetic parameters for the pyrolysis and oxidation of chalcopyrite. The improved kinetic parameters derived from the drop tube studies are used to simulate chalcopyrite concentrate reactions in the reaction shaft of an industrial smelter. The reaction shaft model includes the effects of turbulent fluid mechanics, entrained flow mixing, turbulent particle dispersion, heterogeneous particle reactions, radiative and convective heat transfer, and surface and bath deposition rates. Particle reaction and composition characteristics are predicted as a function of particle trajectory and deposition and are used to aid in evaluating shaft performance.

Jan 1, 1999

By D. M. Jones

In May 1999 the first campaign of the BHP San Manuel flash smelting furnace (FSF) will be concluded after having set world records for both campaign length and tonnage smelted for an Outokumpu copper flash smelting furnace. This paper reviews planned process and equipment modifications including: The installation of a new 36,000 mt concentrate storage facility; replacement of the existing dryer electrostatic precipitator with a baghouse; modification of the FSF dry charge bin and feed system to achieve mass flow and uniform feed to the concentrate burner; modifications to the FSF and its ancillary cooling systems; modifications to the waste heat boiler and offgas handling system to increase gas handling capacity and improve process efficiency;- and improvements to the FSF fugitive gas collection system. A brief review of the planning and execution of the scheduled 45 day shutdown is also given.

Jan 1, 1999

By F. Mucciardi

With the increasing trend to continuous smelting and converting, granulation of copper matte is gaining prominence as a means of decoupling the smelting and converting operations. Moreover, granulation is also being seen as a possible avenue to using higher grade oxygen in converters. By feeding cold solid matte, the oxygen concentration can be increased to compensate for the lower enthalpy feed. This leads to a higher grade of SO2 in the off gas and a lower total flow rate. Current granulation technology relies on the cooling of a falling matte film by water jets. This technology while effective has several drawbacks including those related to safety. Noranda and McGill University have developed a new process (patent pending) for solidifying copper matte (or slag). It overcomes many of the negatives of current technology. The system is based on an air cooled twin roll caster. This: new system uses no water and instead incorporates heat pipe technology to transfer the heat from the solidifying matte to the cooling air to produce a thin strip of 1 to 2 mm in thickness. Testing of a prototype unit demonstrated its viability. This paper describes this newly developed, twin roll casting system that is completely waterless. The advantages of this process as well as the findings from several tests are also detailed.

Jan 1, 1999

By F. Leuzzi

Asbestos is a natural mineral fibre which has been known and utilized commercially for about a century. From the forties, it was employed on an ever-increasing scale throughout the mechanical engineering, building, paper-making and plastics sectors, to name but a few. There are essentially five minerals which provide fibres for industrial applications, namely, the chrysotile variety of serpentine and the amphiboles such as riebeckite, anthophyllite, cummingtonite-grunerite (amosite) and tremolite. About a fifth of the world's asbestos output was once taken by Europe for the manufacture of asbestos-cement products, reinforced plastics, paper and cardboard, panels, soft insulation and spray-on powders. However, in the sixties and seventies the hypothesis regarding the pathogenic nature of asbestos fibres started to gain ground. Moreover, between the sixties and eighties the EU issued a series of regulations designed to bring about a steady decrease in asbestos consumption. This line of action has culminated in recent years in a whole set of directives banning the use of asbestos in all products. This created a major problem, namely, how to clean-up the several million tons of various types of asbestos products in various states of conservation existing in Western Europe. CORDIAM (Pat. RM95 A 000269 and Pat. RM96 A 000782 in the name of ECOTEC S.r.1.) is one of the thermal inertization techniques recently proposed for this purpose. The process provides for the low-temperature ceramization of the toxic-harmful material. Of course, with such a great variety of waste materials and the volumes to be treated, as well as the need to ensure the correct dimensional design of the thermal sections of the treatment plant, it is necessary to know as much as possible about the thermal behaviour of the wastes concerned. This paper details the steps taken firstly to ascertain the thermal behaviour of such materials as may be encountered in day-to-day practice and secondly to examine the influence of the main process parameters on the preliminary design of gas- or fuel-oil-fired rotary kilns of the kind used for waste treatment.

Jan 1, 1999

By J. Etay, S. Daugan, Y. Fautrelle

"New type of electromagnetic parametric instabilities arising at the free surface of liquid metal in the presence of a low frequency magnetic field are presented. First, the mechanism of the instability is analysed in an idealised case. Then, the experimental device working with mercury is described. Various shapes, both regular and irregular, of free surface are found. A experimental stability diagram is obtained. Measurements of the deformation performed on photographs are compared with physical orders of magnitude.IntroductionWhen a liquid metal pool of electroconductivity a is submitted to an A.C. magnetic field B = B0 cos mt, electrical currents j are induced in the liquid metal and interact with the applied magnetic field to create electromagnetic body forces F = j x B. Those Lorentz forces comprise both a mean value (time average) and an oscillating part. Those forces are widely used in many metallurgical processes to stirr a liquid metal or to control its free surface, e. g., in aluminium continuous casting or electromagnetic levitation problems (1-3). When liquid metal free surfaces are submitted to AC. magnetic fields, the shape of those interfaces may interact with the applied field and leads to a various instabilities. A review of these instabilities may be found in Fautrelle (4). That instabilities may be a problem for the control of processing as electromagnetic levitation or quasi-levitation."

Jan 1, 1999

By David Ellis

The next generation of Reusable Launch Vehicle (RLV) will utilize regeneratively cooled combustion chamber liners in the engines. The current design calls for using a new Cu-8 at. % Cr-4 at. % Nb (Cu-8 Cr-4 Nb) alloy for the liners. Work is ongoing to characterize the thermophysical and mechanical properties of the alloy from - 253 to 800°C, the temperature range to which the alloy will be subjected during service. The alloy has been commercially produced in quantity for NASA. The powder size has been characterized and the microstructure examined. The powder was extruded into bar using a commercial extrusion press. In addition, samples have been hot isostatically pressed (HIPed) at NASA Glenn Research Center. Both processing methods produced fully consolidated material. Transmission electron microscopy (TEM) revealed highly faulted Cr2Nb and some elemental precipitates. Cryogenic tensile testing showed the extruded specimens had significantly higher strengths than NARloy-Z (Cu-3 wt % Ag-0.5 wt % Zr) even after being subjected to a simulated braze cycle. The Young's moduli (Cu-8 Cr-4 Nb) were lower than NARloy-Z. The lower moduli is highly beneficial for reducing thermally induced stresses in rocket engine combustion chamber liners and similar applications.

Jan 1, 1999