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By C. J. Newman

Prior to 1995, the smelting process at the Kennecott Utah Copper Corporation (KUCC) smelter consisted of Noranda reactors and Pierce-Smith converters. In the consideration of expansion opportunities, the existing process did not lend itself to a program geared towards processing the total output of KUCC mining and milling operations. During 1989 and 1990, a number of smelting options were evaluated. The final selection was the Outokumpu flash smelting process, coupled with the new Kennecott-Outokumpu flash converting technology. Facilities were designed and installed to process 1:0 million tonnes per year of copper concentrate, with the ability to expand to 1.2 million tonnes per year. Following the shutdown of the smelter facility utilizing the Noranda technology in May 1995, the flash smelting, furnace commenced operation in June with the flash converting furnace startup following a few weeks later. The smelter has achieved design production targets and environmental goals. Current operating rates are at or above design rates for concentrate and matte processing. Emissions are lower than the permit levels and equate to less than 3.5 kg of SO2 per tonne of copper. This paper outlines the design, construction, startup and the first two years of operation of the modernized KUCC smelter.

Jan 1, 1998

By W. -S. Hwang, R. A. Stoehr, P. Ingerslev

"The flow of molten metal entering complex two-dimensional foundry molds has been modeled using the Simplified Marker and Cell (SMAC) and Solution Algorithm (SOLA) techniques. The molds were for a series of four and three-spoke wheel designs. The computer calculations were compared to physical experiments in which molten cast iron was poured into C02-bonded sand molds. The metal was photographed with a high speed motion picture camera focused through a Pyrex glass window on one face of the mold. To get good agreement between the calculations and the experiments, it was necessary to accurately represent the velocity through the ingate. This was calculated by application of the Bernoulli equation to flow through the feed system. Some difficulties were experienced with mathematical instability, expecially in the three-spoke design with a narrow ingate. This was overcome by using 100% upwind differencing, and over relaxation parameter near 1.0 (i.e. no over relaxation), and variable mesh spacing.IntroductionModeling the flow of molten metal entering molds has the potential for making significant contributions to the design of feed systems. It will supply information to the computer-aided-design systems of the future that will enable the designer to optimize the placement of gates, dimensioning of passages, and designation of casting speeds. Such design criteria have generally been based on application of energy balance (Bernoulli equation) principles to flow in the sprues, runners, and gates. Indeed, this is the easiest way to determine the proper dimensions to give a suitable filling time for a casting of a given size. A number of computer programs, including one by some of the present authors, have integrated such calculations into CAD systems. l Modeling the flow of metal inside the mold cavity requires other techniques that will handle free-surface transient flow. Stoehr and Hwang reported on the application of the Marker-and-Cell (MAC) technique to mold filling problems at the previous conference in this series at Hennicker, N.H. in 1983. 2 Although considerable progress has been made since that time in improving the accuracy, stability, and convenience of these techniques, the shapes to which they were applied remained limited. Also, physical verification of the results of the calculations was limited to water models.The work to be reported in this paper was undertaken with two objectives: (1) to apply these techniques to more complex and realistic shapes, and (2) to verify the results by comparison with flow patterns observed in molten metal poured into actual sand molds."

Jan 1, 1986

By A. J. Meir, Paul G. Schmidt

"We present a novel approach to the mathematical analysis and computational simulation of fully three-dimensional, nonlinear, viscous, incompressible MHD flow in complex configurations involving several liquid and solid conductors. Such configurations arise in numerous metallurgical processes. Employing the current density rather than the magnetic field as the primary electromagnetic variable, it is possible to avoid artificial or highly idealized boundary conditions for electric and magnetic fields and to account exactly for the electromagnetic interaction of the flow region with the surrounding space. In addition, the approach lends itself naturally to finite-element based discretization techniques. As an application, we simulate the stationary flow of an electrically conducting fluid around a solid spherical particle of arbitrary conductivity, in the presence of crossed uniform electric and magnetic fields, and compute the Lorentz, pressure, and viscous forces exerted on the particle. This problem arises in connection with the electromagnetic filtration (purification) of molten metals before the casting stage.IntroductionNumerous metallurgical processes are governed by MHD effects resulting from the macroscopic interaction of liquid metals with applied or induced currents, electric and magnetic fields. Frequently these effects are technologically exploited in order to drive or to control the flow of metallic melts. Typical examples include the electromagnetic stirring of molten metals before the casting stage [1]; electromagnetic turbulence control in induction furnaces [2]; electromagnetic damping of buoyancy-driven flow during solidification [3]; and the electromagnetic shaping of ingots in continuous casting [4]."

Jan 1, 1999

By D. H. H. Quon

Results of a study conducted to determine the properties of iron ore pellets made from Mount Wright and Carol Lake ore concentrate fines with partial and full substitution of bentonite by several organic binders are presented. Carboxy methyl celluloses 7H and 6TL, hydroxy ethyl cellulose (natrosol) and modified guar gum all produce pellets of acceptable wet, green and dry strength. However, when fully substituted, an inorganic binder such as calcium carbonate is required for satisfactory strength development after induration. Mixing the Carol Lake ore with Mount Wright ore in a 50-50 ratio also achieves the same result. The failure of the Carol Lake ore in the pelletization process is attributed to the low hematite content of the ore. The results are very similar to those from the extrusion studies reported earlier (8).

Jan 1, 1989

By Arsenio Enriquez, Adrian Deneys

"Rio Tinto through its subsidiary Kennecott Utah Copper Corporation (KUC) and Praxair have implemented the CoJet® gas injection system for copper anode refining. The system provides the capability to melt on average 60 to 70 tons of scrap copper per heat (with acceptable NOx emissions). The system has demonstrated the potential for tuyere-less sulfur and oxygen removal using coherent jet technology.This paper describes the process concept, system development, laboratory testing, implementation, current operation and ongoing developments."

Jan 1, 2009

By Suchun Zhang

The alkaline oxidation of refractory gold concentrates containing arsenopyrite and pyrite at ambient temperatures and pressures has been found to be accompanied by the simultaneous dissolution of gold without the addition of cyanide. A detailed study has been made of the kinetics of the oxidation of the pure minerals and of several concentrates. The reaction products of the oxidation of arsenic and sulphur have been monitored using chromatographic techniques. In the case of arsenopyrite, thiosulfate, monothioarsenate, arsenate and sulfite are the principal products while thiosulfate has been confirmed to be the dominant product of pyrite oxidation. Gold, either as added powder or as a constituent of the concentrates has been found to dissolve simultaneously during the alkaline oxidation of both arsenopyrite and pyrite, and this appears to be associated with the in-situ formation of thiosulfate as a lixiviant. The effects of temperature, stirring speed, oxygen partial pressure, alkalinity and pulp density on the oxidation of arsenopyrite and the dissolution of gold have also been investigated. Keywords: Gold, dissolution, arsenopyrite, pyrite, alkaline, oxidation, thiosulfate, thioarsenate

Jan 1, 2005

By A. M. T. S. Bandara

The solubility of rare earth (RE) salts in aqueous solutions depends on many factors including the type of cations and anions in solution, their concentrations, temperature and the type of solid precipitated. Experiments were conducted using anhydrous La2(SO4)3 and Ce2(SO4)3⋅8H2O as solids and lanthanum(III) perchlorate prepared by dissolving La2O3 in HClO4 solutions as RE-sources. Solutions of H2SO4, H3PO4 and their mixtures in the presence or absence of Na+, Ca2+, Fe(III) or Al(III) as perchlorates served as test solutions. Saturated solutions and precipitated solids were assayed and characterized using standard techniques to show that the La(III) and Ce(III) ions precipitate as hydrated sulphates, phosphates or double salts with sodium, depending upon the solution composition. The change in solubility of RE-salts with solution composition and temperature is the result of the composite effect of changes in solubility products (pKSP) of salts, pKa of acids and other equilibrium constants for ion-association.

By J. Borlée, J. P. Birat

"ULCOS is a large European program launched by a consortium of 48 partners led by arcelor and a core group of steel producers, which was started in 2004 with the support of the European Commission (RFCS and 6FP programs) to search for breakthrough process routes that could, in the future, when fully developed, demonstrate the potential of large cuts in CO2 emissions for the production of steel from iron ore.The timescale for commercial implementation is the post-Kyoto period, i.e. 15 to 20 years from today.The present paper presents the progress made in the first 2 years of this 5 year program.Several concepts are being investigated in parallel: re-engineering of the blast furnace to incorporate CCS in the core of the process, smelting reduction with CCS capabilities, massive use of natural with more CO2-lean technologies than today, hydrogen steelmaking and electrolysis of iron ore. Biomass also offers very attractive perspectives, while raising major challenges.None of these new steelmaking routes are ""no regret"", which means that the European Steel Industry has already incorporated extensive energy saving steps in its present process technology and is working as close to thermodynamics limits as is cinematically and economically feasible, and that decreasing GHG emissions further means introducing breakthrough technologies that add significant costs to the operation of the Steel Mills.They will also require much research and development before they can be proven and implemented commercially.IntroductionThe ULCOS program (Ultra Low CO2 Steelmaking) is a large research program of the European Steel Industry and its industrial and research partners launched in September 2004 to investigate steelmaking technologies that have the potential of reducing the CO2 emission of the Industry by a large amount, typically in the order of 50%. It is supported in the European Community by the 6th Framework and the RFCS programs through 3 complementary European projects [1,2].The present paper summarizes the work carried out in the phase 1 of ULCOS and in framing the program of phase 2."

Jan 1, 2008

By J. Hamisch

Climate policy regarding perfluorocarbons (PFCs) may have a significant influence on investment decisions in the production of primary aluminum. This work demonstrates an integrated analysis of the effectiveness and likely economic consequences of different climate policy options. In our study we first compare atmospheric observations to the available estimates of PFC emissions for the baseline years 1990 and 1995. We then present projections for regional emissions of PFCs from the aluminum industry using the MIT Emissions Projection and Policy Analysis model under different policy scenarios. Abatement costs for emissions of PFCs and C02 are compared in the context of the Kyoto Protocol.

Jan 1, 1999

By Stein Tore Johansen, Fionn Iversen, Jon Arne Bakken

"A new marker chain front tracking method is used for modelling the meniscus movement during DC casting of aluminium ingots. Modifications have been made to an earlier method developed by Popinet and Zaleski [12] to adapt the model for simulations of meniscus dynamics in the casting process.Initial casting simulations show that wetting conditions in the mould greatly influence the meniscus stability. Controlling the wetting conditions seems to be important for improving the cast ingot surface quality.IntroductionIn conventional direct chill (DC) hot top casting of aluminium extrusion ingot with gas-slip poor surface quality of the cast ingot can be a problem. In the worst cases pronounced surface wrinkling occurs coupled with periodic zones of reduced grain size, macrosegregation and exudation at the surface. The observed surface irregularities are believed to be linked to Periodic surface oscillations or folding of the meniscus resulting in varying solidification conditions.The focus of this work is to gain a better understanding of the dynamics of the meniscus and the influence it has on the finished cast ingot surface through numerical simulations of meniscus movement during the casting process.A two phase marker chain front tracking technique[12] using cubic spline surface reconstruction is applied for modelling the meniscus movement. The advantage of this type of model is its accuracy in the calculation of surface tension forces. Also the wetting can be implemented directly as a boundary condition on the surface spline function. The method is applied in the FLUENT solver, which is based on a finite volume method using the SIMPLE algorithm."

Jan 1, 2001

By Makiko Takahashi

A tool is being developed to predict and visualize the microstructural evolution of steels during quenching. This tool utilizes experimental data and reference data that are stored in a database to predict the microstructural development. The visualization tool animates qualitative representation of two- dimensional microstructure drawings as well as the quantitative volume fractions of phases present as a function of time. This is achieved by superimposing the Jominy End-Quench test results over the Continuous Cooling Transformation diagram of the alloy. The predicted microstructure is presented through the web browser to maximize the ease of use. In addition, a parallel coordinate system is used to aid in identifying similarities within the data set by presenting the large number of data at a glance. The results for 4140 steel that was quenched in a wide variety of quenchants will be presented to illustrate the prediction and visualization tools. Keywords: Quenching, Microstructure Prediction, Simulation, Data Visualization, Database, Applet, Animation

Jan 1, 2003

By Raymond F. Dalton

Despite the ready availability of numerous zinc sources, the process of solvent extraction- electrowinning (SX-EW) has as yet found little favour in the zinc industry. It is suggested that this is largely due to the previous lack of availability of suitable selective reagents having the particular features required to enable them to fit in to a solvent extraction-electrowinning based process for zinc, particularly with regard to strength and selectivity for zinc over iron. This paper describes work on the development of new selective extractants for the recovery of zinc from both sulfate and chloride aqueous solutions and suggests how they might be integrated into new zinc processes.

Jan 1, 1994

Equilibrium calculational software programs can be effectively utilized to illustrate the importance of activity or concentration, solubility, temperature, solution pH, solution potential, and ligand complexation to students studying hydrometallurgy. The calculational program STABCAL will be demonstrated. illustrative examples for the creation of diagrams such as EH-pH, activity or concentration-pH and activity or concentration-EH will be presented to demonstrate the fundamentals of real hydrometallurgical systems. Speciation, titration and mixing will be used to simulate or predict operational processes. Applications will include treatment of Acid Mine Drainage (Berkeley Pitlake water and sediments), mass balance potential/pH diagrams, leaching and selective separation of metals from electroplating sludge, metal adsorption at femhydrite surfaces, and flowsheet development for treating mercury sulfide K106 sludge.

Jan 1, 2002

By Farzaneh Sadri

After water leaching of an acid baked REE concentrate, impurities such as Fe, Al, Th, and Cu are removed by neutralization with different reagents such as NaOH, Mg(OH)2, MgCO3, CaO, and CaCO3. Among these chemicals, lime (CaO) and limestone (CaCO3) are the preferred reagents due to their low costs. However, because of calcium sulfate dihydrate (gypsum) precipitation, they are not so common in industry. One of the disadvantages of gypsum precipitation is the adsorption of REE to the precipitates, losing a fraction of REE to gypsum which is hard to recover. In this paper, batch and continuous conditions in the impurity removal process using limestone are investigated and the differences between these two processes are examined. Based on the experiments, REE uptake by gypsum significantly increases in continuous processes, and different gypsum morphologies are observed.

By Adam J. Gesing

Eddy current separators are increasingly used by the auto shredder operators to produce higher grade of nonferrous metal concentrate for recycling. While this increases the unit price of the concentrate, metal losses through inefficient metal recovery quickly offset the price differential. We show how to optimize the eddy current separation system at the shredder to maximize mate- rial throughput, nonferrous metal recovery and grade of the nonferrous metal concentrate.

Jan 1, 1998

By C. E. Abbey

Cobalt, iron and manganese play various roles in copper electrowinning using lead–calcium–tin alloyed anodes. Cobalt catalyzes electrochemical water decomposition resulting in lower anode potential and reduced corrosion rates. Iron reduces cathodic current efficiency, but is used to reduce higher oxidation states of manganese that oxidize organics in solvent extraction. Manganese also produces anode scale and is generally considered a problematic impurity. The effect of the combined interaction of these three metal ions on the anode potential has not been quantified yet. The current work used a three factor, two level, three replicate central composite design of experiments to analyze the effects and potential interactions among cobalt, iron and manganese. The experiments consisted of chronopotentiometric analysis to assess anode potential after 24 h of operation. Higher [Co], lower [Mn] and either high or low [Fe] yielded lower anode potentials. Two regression models were developed to predict anode potential as a function of [Co], [Fe] and [Mn]. A method to estimate electrical energy consumption for copper electrowinning is also presented.

By W. G. Davenport

The offgas from flash furnaces inadvertently contains dust. The dust contains 25 to 30% Cu so it must be treated for Cu recovery. This is almost always done by recycling it back through the flash furnace*. This chapter shows how dust production/recycle is included in our matrix calculations. It then discusses the effects of dust production/recycle on flash furnace industrial oxygen and oil requirements. It concludes that re-smelting of dust requires considerable industrial oxygen and fuel, so that dust production should be minimized. Recycled dust also takes the place of new concentrate in the flash furnace feed system, decreasing Smelter productivity -another reason to minimize dust production. Compositions of industrial dusts are given in Appendix VII and Table 18.3. Industrial quantities are given in Tables 2.1, 3.1, 19.1,20.1' and Appendix VI.

Jan 1, 2001

By Dan Wang, Yuanbo Zhang, Guihong Han, Guanghui Li, Tao Jiang, Yanfang Huang

"Hematite concentrates are characterized by bad high-temperature reactivity and poor balling index, which restrict their large-scale application in the production of oxidized pellets. An organic additive, namely MHA, was authorized and used as binder recently in China. Compared with bentonite, the effects of MHA on compressive strength of hematite pellets at various firing conditions were investigated in this study. Experimental results showed the compressive strengths of preheated pellets with different binders were increased with increasing the preheating temperature and time. The compressive strength of preheated pellets with MHA binder was lower than that of pellets with bentonite, which can be ascribed to the high porosity of pellets with MHA binder. However, the compressive strength of roasted pellets with MHA binder was higher than that of pellets with bentonite. The compressive strength of finished pellets balled with MHA binder 1.0 wt% could meet the operation requirements of grate-kiln process.IntroductionHematite concentrates are characterized by bad high-temperature reactivity and poor balling index, which can lead to the appearance of those problems with increasing the energy consumption, shortening the useful life of equipment, and finally increasing the operation cost of oxidized pellets plants [1-2]. Some investigations have been conducted based on improving the pelletizing technique of hematite concentrates, such as pretreatment of raw materials [3-7], optimization of ore proportioning [8], addition of solid fuels [9-16], and so on. Employing high pressure grinding roller for the treatment of hematite concentrates revealed that the mechanical strength of wet green pellets could be improved. However, the mechanical strength of fired pellets was not improved obviously [7]. Huang, et al., pointed out that the preheating and roasting temperature may be decreased and the compressive strength of fired pellets could be increased by blending a certain proportion of magnetite concentrates with hematite [8]. Nevertheless, there are a variety of magnetite ores different in physical and chemical properties in China, resulting in the instability operation [17]."

Jan 1, 2012

By T. Feldmann

Despite the ubiquity of applications for germanium, there is a lack of practically useful solubility data in acidic solutions. Previous studies were done at ambient temperature and only for commonly used acids (H2SO4, HCl). Hence, an investigation of the solubility of GeO2 in different acids was undertaken. Several inorganic and organic acids were studied in the concentration range of 1–11 mol/L and at 23, 40, and 60 °C. In the case of H2SO4 and HCl previous data was confirmed. Lower acidity resulted in a higher solubility for Ge at all tested temperatures. Tests done at 40 and 60 °C and low to moderate acidity levels, gave slightly increased solubility values at higher temperatures compared to 23 °C. This wasn’t the case at higher acidity levels, i.e., the solubility curves at different temperatures converge at high acidity. Lastly, a relationship of water activity and GeO2 solubility in different acid media was established.

Arsenic occurs naturally in rocks and soils, water, air, plants and animals. It can be further released into the environment through natural activities such as volcanic action, erosion of rocks and through human actions. Higher levels of arsenic tend to be found more in ground water sources than in surface water sources of drinking water. Compared to the rest of USA, western states have more systems with arsenic levels greater than 10 parts per billion (ppb). The US Environmental Protection Agency (EPA) has historically regulated arsenic in drinking water at 50 ppb, but the agency has lowered the maximum contaminant level (MCL) for arsenic to 10 ppb-to be in compliance by January 2006.This paper reviews briefly a) aqueous arsenic chemistry and removal mechanisms and b) the available treatment processes to attain the drinking water standard of 10 ppb by 2006. The combining of an appropriate removal method with an existing system depends on several factors such as nature of arsenic, the water source, existing plant equipment and processes site conditions etc. The paper also includes one or two case studies from the State of Arizona. Key words: Arsenic, Drinking water, Treatment Technologies

Jan 1, 2005