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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 David Hughes

The paper covers the utilization of on-line analysis in process control of solvent extraction in nickel leach solvent extraction processes in Finland and Australia and in copper heap-leach and solvent extraction in Chile. The goals of and requirements for controlling the solvent extraction stages of the processes are reviewed. The applications at three plants are compared. The development of the technology used is reviewed and design considerations are discussed. Requirements for on-line control and analyzer performance are compared. A new generation of analyzers and its effect on the set-up process of a project is introduced.

Jan 1, 2003

By S. M. I Kytö, J .. K. Mäkinen, K. Saarhelo

"At the Outokumpu Oy Harjavalta Copper Smelter the control philosophy of the flash smelting process has been changed from the slow feed-back control to feed-forward control. This is important as the fluctuations in the flash smelting furnace matte grade and slag temperature are desired to be minimized.The system is based on a specially designed automatic sampling device and the Outokumpu Courier 20 on-stream X-ray fluorescence analyzer. A microcomputer-based Analyzer Operator Station (AOP) controls the system and calculates the process parameters for the furnace from the analyzed chemical composition and other existing data.A considerable reduction in the deviation of the matte grade and slag temperature has been gained. This has resulted in conservation of energy and refractories, lower copper losses and higher through-put in the flash smelting furnace and converters.1.0 IntroductionThe flash smelting technology for copper concentrates was developed at the Outokumpu Oy Harjavalta Smelter soon after the World War II. The incentive for this development was shortness and high price of any form of energy. The fact that smelting can be carried out autogenously, without external energy by utilizing the latent heat of sulfide combustion was known decades before, but Outokumpu Oy was the first company to take the advantage of this knowledge in practical operation. A further advantage of this technology was that the SO2 containing gases suited well for sulfuric acid production, thus minimizing the detrimental effects on the environment (1).The very heart of the flash smelting process is the reaction shaft of the flash smelting furnace (see Appendix I). Heating up of the dried feed mixture, dissociation of several compounds, ignition and oxidation of the feed take place very intensively in the reaction shaft during 2 - 3 seconds, which the fine grained particles reside in the reaction shaft. A very accurate control of the amounts of the feed materials as well as of oxidizing gases, fuel, etc. is of primary importance."

Jan 1, 1989

By Richard Krentz

Two separate on-line analyzers are operated at the Corefco metals refinery. The first application is an on-line refractometer which measures the ammonium sulphate concentration in the primary feed slurry tank. The second application is a multi-stream X-Ray fluorescence analyzer which measures the metals and sulphur concentrations in eight key refinery streams. Specific applications of the on-line analyzers with advanced control systems for improved process control will be discussed.

Jan 1, 2003

By Brian G. Thomas

Quality problems in continuous casting of steel can be identified as they occur by monitoring mold signals (level sensor, thermocouples in the mold walls, friction etc.) and taking appropriate action (such as slowing casting speed, changing taper, changing a clogged nozzle, or later visual inspection of the surface for possible downgrading. Surface depressions and groups of deep oscillation marks form at meniscus and reduce local heat transfer as they move down the mold at the casting speed. This slows shell growth, increases shell surface temperature, and causes characteristic dips in mold thermocouple signals. More importantly, they are also associated with longitudinal cracks. Characteristic thermocouple signatures have been identified for many defects, including sticker breakouts, transverse depressions and deep oscillation marks, narrow-face bleeds, transverse comer cracks, longitudinal cracks, mold level fluctuation defects, and other problems. With the help of computational models, these mold signals should be used to troubleshoot defects, and to take appropriate corrective action. Keywords: Continuous casting, defect detection, thermocouple signals, on-line control

Jan 1, 2003

By M. Huang

A conductivity-based sensor for on-line measurement of free acid was recently built. This sensor is suitable for high ionic strength solutions and its corrosion-free operation is based on induction currents. It has been tested against literature data and measurements made using a previous developed contact-type conductivity cell, with an average difference within 1%. The electrical conductivities of H2SO4?H2O, H2SO4?MgSO4?H2O and NaCl?Laterite-H2Osolutions at temperatures up to 250 °C were discussed. It was found that the solution conductivity depends on various factors, such as the electrolyte concentrations, the type of electrolytes, temperature and the amount of dispersions. A semi-empirical model was developed to account for all the factors discussed. This model was further tested on actual process solutions from the hydrometallurgy of nickel where sulphuric acid solutions containing a variety of metal sulphates and solids. The average difference between the estimated acid concentration from this model and the one from titration was generally less than 5%, which is excellent for industrial applications.

Jan 1, 2006

By Derek J. Fray

"A need exists for fast and accurate analysis of species in various phases at elevated temperatures. Although modern analytical techniques are very efficient, the equipment is usually situated some distance from the industrial operation and time is spent taking the sample and sending it to the analytical facility. Several minutes can easily lapse and, during this time, heat must be supplied in order to keep the system molten and, if the composition is changing rapidly due to a refining process or reaction with the environment, the information may only be of retrospective use. Perhaps more important reasons for the use of on-line sensors are that instantaneous analysis gives better control, process optimisation and the minimisation of energy losses and pollution. To date oxygen has been the only element which is measured widely using solid electrolytes. However, the analysis of many more elements is required and possible electrolytes for other species are discussed. For some elements, ~here is no suitable conducting electrolyte and, therefore, a different approach is adopted where the electrolyte, in which one species is mobile, comes to equilibrium with another species. IntroductionThere is an ever increasing demand for the development of sensors for on-line measurements in most areas of technology and, in particular, metal processing. This is especially relevant in situations where greater control can be achieved by monitoring the chemical composition of the melt during processing and where a minor constituent in the melt can have a major effect on the properties of the finished alloy. Although modern analytical techniques are fast and reliable, the equipment due to its complexity, is frequently situated away from the process area and valuable time may be spent in sampling and transportation. During this period, heat may have to be supplied to prevent solidification and the refining reactions may be continuing, and, therefore, the analytical information may not be of direct use."

Jan 1, 1988

By Cheryl S. Lim

New technologies such as direct reduction and smelting reduction processes are increasingly being used in iron-making and steel-making in addition to conventional blast furnace technology. Critical parameters for control of these processes include the degree of metallization, degree of pre-reduction, and carbon and silica levels. On-line monitoring of these parameters is difficult because measurements often need to be made on hot ores (at or higher than -1000'C) in circumstances where representative sample streams are not readily accessible. A nuclear analyser has been developed which provides continuous, non¬intrusive, real-time measurements of iron, oxygen, carbon and silicon levels in hot ores undergoing reduction. The analyser has been tested in a plant using a direct smelting process on pre-reduced feed to the smelting vessel-, accuracies of 1% relative, 0.5 w'.96 (25% relative) and 1.0 wt.% (9% relative) were obtained for the degree of pre-reduction, carbon and silica respectively. The underlying method, capabilities and potential applications of the analyser will be discussed.

Jan 1, 2001

By Daniel Bennett

There are few methods currently applied towards on-line bulk mineralogical analysis. Yet on-line knowledge of process mineralogy could potentially provide large benefits, such as increased extraction efficiency or resource optimization. The work described in this paper involves the development of radio frequency methods for bulk mineralogical analysis. Some resonances that occur in the radio frequency spectrum are mineral specific, and potentially allow quantitative estimation of mineralogy in an ore stream. Results will be presented on the specific detection of chalcopyrite. Initial quantitative measurements investigating matrix effects have indicated the feasibility of on-line mineralogical estimation using radio frequency techniques.

Jan 1, 2006

By Larry M. Southwick

The smelting of copper and other non-ferrous metals have made considerable advances over the last 125 years. Many of the ideas and processes currently in use were attempted early in the history of smelting and were unsuccessful. Often the cause was incomplete understanding of the metallurgy involved, inadequate refractories, poor materials of equipment fabrication or trying too many new ideas at once. With time, these problems get solved and the technologies become commercialized .These were processes whose time had not come when originally proposed, but did eventually. On the other hand, there have been some concepts whose time will never come. They were impossible then and they are impossible now. The people that dream these up were either crackpots (they didn't know what they were doing, but thought they did), or charlatans (they knew they didn't know what they were doing, but didn't care). Both rely on bad science to propose metallurgical absurdities. These too have their place in the development of technology, though mostly negative, and several examples will be discussed in this paper. Three from around the turn of the century will be covered, as well as one from this decade. The last demonstrates that the art of creating absurdities has not withered, even after ninety years of scientific sophistication, and some can even be patented. The first three reached field trials due to the gullibility of company management. The last arose from a fortuitous mis-operation of a plant which solved a problem, but the explanation and patent which arose are metallurgically impossible.

Jan 1, 1999

Lance based copper-nickel matte converters have become an established technology in the field of base metal sulphide smelting and converting. An Ausmmelt® converter is currently being constructed at Anglo Platinum in South Africa to convert a nickel-copper rich matte containing platinum group metals (PGM's). The accurate prediction of the matte chemistry is required to control the composition at the endpoint which influences segregation of PGM's during the subsequent slow cooling and magnetic separation processes. A hybrid modelling approach is introduced in this paper that incorporates both the effect of thermochemistry and system dynamics. It will be shown how the model relates to fundamental conservation laws, while still providing enough flexibility to adapt to changing operating conditions. It will also show how off-line modelling can be incorporated into a robust on-line model. Based on the data from many pilot plant trials, the model prediction performance is shown to be within the accuracy requirement set by industry and therefore constitutes a reliable basis for model based control. The final generic model structure takes on the form of an thermodynamically integrated ARMAX hybrid model. The final model has the advantages of being dynamic, adaptive, robust and it can be related to thermochemical fundamentals.

Jan 1, 2002

By A. A. Shook

The off gas from the #5 converter at BHP Copper's San Manuel smelter was analyzed continuously over a period of several weeks using an online sulfur dioxide analyzer. These data have shown that the oxygen utilization efficiency of this copper converter was somewhat lower than anticipated, and that oxygen efficiency declines significantly during the copper blow. A sharp reduction in sulfur dioxide generation was consistently observed at the end of the copper blow, which could be used by converter operators to prevent over-blowing and minimize rolling out of stack.

Jan 1, 1999

By Akihide Hosokawa

The void growth and coalescence in model materials involving a pre-existing three dimensional void array (i.e. multiple layers of a void array) was studied by X-ray computed tomography (XCT) coupled with in situ tensile deformation. To reduce the recording time, a new technique called fast tomography was employed. The model materials used in this paper were fabricated by the combination of an ultra-short pulsed laser machining system and a diffusion bonding technique, and two different types of arrays were prepared namely, FCC 1 and FCC 2 type array. This methodology allowed the authors to capture the entire process of growth and coalescence events of a void array embedded in the metal matrix. The failures in the both materials involved internal necking and shear localization. One of the highlights of this paper is that the plastic strain at the onset of void coalescence was measured for each model material. These values are in fact the adequate values to be compared with the coalescence strain predicted by existing void coalescence models such as the Brown and Embury model, the Thomason model and the Pardoen and Hutchinson model. The comparison suggested that the Brown and Embury model underestimated the coalescence in neither of the current model materials, while the Thomason model and the Pardoen and Hutchinson model showed a quite good agreement with the result for FCC 1 material. On the other hand the result from FCC 2 material agreed with none of the models probably due to the geometry of the void array that is not compatible with the existing models.

Jan 1, 2010

By Raymond PoIick

The Demag Electric Slag Cleaning Furnace installed at the Asarco Smelter in Hayden Arizona is one of the few rectangular electric furnaces now operating. The long transition times from charge to tap allow exceptionally clean skims (high recovery); however, the furnace design is complex. Additional Asarco requirements for rapid installation and commissioning further complicated the design. When operating and wear effects accumulated after two years of use, steps were taken to rebuild the furnace with enhanced durability based on the design parameters experience in actual use.

Jan 1, 1993

By L. Deininger

The QSL plant in the existing "Betzelius" Stolberg GmbH lead smelter in StolberglGermany was commissioned in August, 1990. Following some modifications to the process and equipment which had become necessary in line with the implementation of this new techno- logy, conclusive operating results are now available. These will be reported together with a short description of the plant design. In May 1992, raw material feeding to the QSL reactor in the new lead smelter of Korea Zinc Co. in OnsanlKorea was started. As all the experience gained up to that point in time in the Stolberg plant had already been incorporated in this plant prior to start-up, it reached stable, satisfactory operating conditions in a short period of time. After an introductory description of the plant important operating results will be reported. The operating experience gained in the two plants fully confirms the correctness of the in- ventors' creative ideas in the 70s. The QSL process meets all demands made on modern, ecologically compatible and energy-saving lead production technology. The paper ends with suggestions on how the QSL process will be optimized further in the future.

Jan 1, 1994

By B. G. Belew

Recent operating improvements at the Phelps Dodge Chino Smelter, coupled with intensive capital expenditures since 1987, have resulted in a safer, higher quality, more productive smelter. This paper briefly reviews the flowsheet of the Chino Smelter with emphasis on recent capital expenditures. The main focus of the paper is to provide case studies of how operating functions have been improved. Case studies presented include: (1) safety, (2) anode quality control, (3) flash furnace cross-over build-up control, and (4) flash furnace temperature control. Most of these accomplishments have been achieved by providing specific measurable goals and subsequent feedback to operating crews.

Jan 1, 1993

By S. Tanaka

The Tamano Smelter of Hibi Kyodo Smelting Co. Ltd. was commissioned in 1972. Since start up, the anode production capacity has increased from 101,000 tpy to 290,000 tpy, as a result of the application of continuous improvements at each phase of the expansion projects. The Tamano Smelter had developed several innovations, including the original coke combustion technology for Flash Smelting Furnace operations (T-FSF), and has also been able to extend the operating life of the Peirce-Smith converters. This paper will present several improvements implemented at the Tamano Smelter, and will discuss relevant P-S converter operation.

Jan 1, 2005

By H. Hirayama, T. Okura, O. Kato

"Saganoseki Smelter & Refinery, one of the largest copper smelters in the world, has the annual capacity of 300,000 metric tons in copper content with two flash furnaces, six Pierce-Smith type converters, two anode furnaces, four acid plants, three tank houses and perfect pollution control system.Coping with the many severe conditions surrounding the copper industry in the last decade, Saganoseki Smelter has kept performing the stable operation, while enhancing the smelting capacity and developing new technologies such as the hydrometallurgical treating of converter dust recovered at electric precipitators. Especially in the operation of flash furnaces, which are of Nippon Mining's conversion type using hot air in a temperature of l,000ºC some technological improvements and complete operation control factors have approved the concentrate feed rate to reach to 2,200 tons a day for a flash furnace.Reported in this paper are the production control design for copper smelting process, and the operation control scheme of the flash furnace following the brief review of the characteristic of Saganoseki Smelter's process and some improvements. Copper Smelting ProcessDescriptions of major unit operations and general specifications of the copper smelting facilities are summarized in Table 1, and the present flowsheet of the copper smelting is described in Figure 1 (1,2).Outputs and raw materials treated in the last five years are shown in Table 2, in which concentrate includes powder copper scrap which amounts to 3 to 4% of concentrate.A full operation was performed for a period of one month, for both one flash furnace operation and for two flash furnace operation. With one furnace operation, 19,200 tons of copper were produced. With the two furnace operation, 84,000 tons of concentrates were charged and 33,500 tons of anode (net 28,600 tons of copper) were produced.The actual production level, however, has been kept at 80 to 90% of the full capacity because of low copper price, tight market of copper concentrate or fall of net demand in Japan."

Jan 1, 1989

By M. Vondersaar, B. Bulnes

Quemetco, Inc.,. as a subsidiary of RSR Corporation, operates one of RSR's three secondary lead smelters in the City of Industry, California, next to a residential area within Los Angeles County. The Reverberatory furnace serves as the main reactor for melting lead grid and paste recovered by the battery crushing system. Feed material is introduced via screw conveyor after drying in an upstream rotary kiln. Slag produced by the Reverb flows directly to an electric arc furnace. Products from this one-pass furnace system consist of soft lead bullion from the reverb, hard lead bullion from the arc furnace, and a non-hazardous slag from the arc furnace. Furnace bullion is processed into finished product in a six-kettle refinery. An overview ·of plant operations is presented. Where applicable, references will be made to changes that have taken place during the last decade.

Jan 1, 2000

By A. J. Schindler, F-P Sawyer, T. Logan, M. L. Shutey-McCann, R. M. Perry

"Test work on biooxidation pretreatment of low-grade refractory gold ores has been ongoing at Newmont Gold Company since 1988, including laboratory testing and pilot biooxidation heaps (360 to 23,000 tonne). Metallurgical results of the biooxidation process utilizing Thiobacillus ferrooxidans (T. ferrooxiddans) have culminated in the design, construction, and operation of a biooxidation demonstration facility. The facility has processed 708,000 tonnes of refractory ore, using a batched process with separate pads for biooxidation and ammonium thiosulfate gold extraction. Siliceous sulfidic refractory (SSR) and carbonaceous sulfidic refractory (CSR) ores are treated separately during biooxidation pretreatment unit operation. Following biooxidation, the ores are neutralization with lime and placed on oxide leach pads or stacked on the ammonium thiosulfate leach pad. Gold is leached with either cyanide for SSR ores or ammonium thiosulfate for preg-robbing CSR ores.This paper will only address the biooxidation pretreatment process of the SSR and CSR ores.AcknowledgmentsThe authors appreciate the cooperation and approval of Newmont Gold Company Carlin Operations management for its support and permission to publish this paper. The paper draws on efforts and assistance of the following people and several others which are to many to list who participated over the past five years in bringing this project to its fruition: Dr. James A. Brierley, Chief Microbiologist, Newmont Metallurgical Services; Dr. Rong-Yu Wan, Metallurgical Manager, Newmont Metallurgical Services."

Jan 1, 1997