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By Klaus Gamweger

There are different reasons for purging a metal bath. The operations are varied, for example the purging gas can be used as a reactive gas being part of the metallurgical process or as an inert gas using the rising gas bubbles for agitation only. The different purposes for agitation, chemical and thermal homogenization or a preferential movement of the slag to the slag skimming door have to be considered. It depends on the furnace type and its dimensions as well as the process characteristics what the focus is on. For an optimized arrangement of numbers and position of all single plugs in the furnace, mathematical modeling - the CFD Computational Fluid Dynamics method - is used. This paper shows how the operation of purging plugs can influence the metallurgical process of an anode furnace by the example of Jinchuan Copper in China. The potentials for savings in energy consumption as well as in time for oxidation and reduction are presented.

Jan 1, 2006

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

By Susumu Okabe

Mitsubishi Continuous Copper Converter employs the top blowing lance system for the continuous supply of reaction gases into the molten bath. In order to avoid the excessive refractory wear caused by the melt splash without loss of the reaction efficiency, the furnace design and the blowing condition should be optimized. Empirical equations which correlate the splashing rate on the' side wall with the dimensions of the furnace, lance position, lance size, gas velocity and bath properties were obtained by by the physical model study, and compiled into a computer program. The computer program is effectively utilized for the analysis of the actual operation and for the optimum design of new furnaces.

Jan 1, 1998

By Ximena Massone

Chile is the most important copper producer in the world and the mining sector plays a key value in its economy. However, at present the country does not have a satisfactory set of regulations about closure and restoration of mining operations. In our country many mining operations will, in the near future, shut down their activities, therefore, it is of utmost importance to elaborate and enforce a set of regulations to prevent risks and to protect the environment. The present study is focused on reviewing and analyzing the existing national regulations about the closure of mining operations and preparing a comparative analysis with other international regulations of countries with mining experience. The final results of the study will be a legal proposal to regulate the closure of mining operations in Chile, aiming at minimizing the potential environmental adverse impact, internalizing the social costs by the relevant operators and defining all aspects of liability for the environmental damage.

Jan 1, 1999

By Gabriel Plascencia

Copper was oxidized in the temperature range from 300 to 1000 °C under different pressures of oxygen, In the range from 300 to 500 °C, copper oxidizes following the logarithmic rate law; while in the range from 600 to 1000°C oxidation follows the parabolic rate law. Transition from logarithmic to parabolic growth occurs at about 525°C. X-ray diffraction was performed on oxide scales to account for the CuO/Cu2O ratio at different temperatures. Activation energies found in this work are in good agreement with reported values.

Jan 1, 2003

By Gabriel Plascencia

Copper was oxidized in the temperature range from 300 to 1000 GC under different pressures of oxygen. In the range from 300 to 500°C, copper oxidizes following the logarithmic rate law; while in the range from 600 to 1000°C oxidation follows the parabolic rate law. Transition from logarithmic to parabolic growth occurs at about 525°C. X-ray diffraction was performed on oxide scales to account for the CuO/Cu2O ratio at different temperatures. Activation energies found in this work are in good agreement with reported values.

Jan 1, 2003

By Patricio F. Mendez

This paper presents a formalism to automate portions of the traditional scaling procedure. This formalism, called here Order of Magnitude Scaling (OMS), captures essential components of the governing equations into a set of matrices and arrays amenable to computer implementation using standard linear algebra tools. This approach is valid and specially useful for large systems of multicoupled equations. The matrix approach proposed enables one to automate operations such as normalization, dominant balance, obtention of characteristic values, and check for self-consistency. Also, automation permits an exhaustive exploration of all possible balances and the discovery of unsuspected scaling laws. As an example, OMS is applied to the analysis of the viscous boundary layer with no external pressure gradient. The obtained scaling laws for boundary layer thickness and transverse velocity are the same as those obtained with traditional scaling, and in addition, a meaningful estimation for pressure variations within the boundary layer is obtained; this last estimation is typically not addressed in the manual analysis.

Jan 1, 2006

By Masayuki Kudoh, Kiyotaka Matsuura

"Molten aluminum and nickel cast onto a steel block exothermically react and produce molten nickel monoaluminide, NiAI, which is simultaneously joined to the steel. The heat of the exothermic reaction is transferred to the steel block, and steel near the surface of the block is melted. The depth of the melted steel increases with both the initial temperature of the steel block and the thickness of the produced NiAI. Iron from the melted steel dissolves in the molten NiAI, and an intermetallic compound of NiAI-Fe pseudo-binary system is produced. During solidification of the intermetallic compound, it is strongly joined to the steel. The Ni.Al-Fe intermetallic compound has an excellent resistance to oxidation and corrosion.IntroductionAn intermetallic compound of nickel monoaluminide, NiAl, offers many advantages over conventional superalloys, such as higher melting temperature, lower density, greater specific modulus and higher thermal conductivity [1]. NiAl also exhibits excellent high-temperature oxidation resistance when doped with zirconium or hafnium, and excellent high-temperature corrosion resistance when doped with chromium or yttrium, that are superior to existing high temperature alloys or coating materials [1-4]. On the other hand, NiAI is significantly brittle at temperatures below 600 K [5-7], which is the most sigriificant disadvantage of NiAI. A possible way to overcome the disadvantage and to utilize NiAl as an environmental-resisting high-temperature structural material may be joining of NiAl to a ductile material."

Jan 1, 2000

By Timothy W. Skszek, Adrian S. Sabau, Hebi Yin, Gerard M. Ludtka, Xiaoping Niu

"A constitutive model has been developed to predict the yield strength aging curves for aluminum casting alloys during non-isothermal age-hardening processes. The model provides the specific relationship between the process variables and yield strength. Several aging heat treatment scenarios have been investigated using the proposed model, including two-step aging recipes. Two-step aging heat treatments involve a low temperature regime to promote nucleation of secondary phases and a second step at higher temperature for the growth of the secondary phases. The predicted results show that a yield strength of approximately 300MPa might be obtained in a shorter aging time, of approximately 30 minutes. As a result, better mechanical properties can be obtained by optimizing the time-temperature schedules for the precipitation hardening process of heat treatable aluminum alloys.IntroductionA356 is one of the commercially heat treatable aluminum casting alloys, and T6 is one of the heat-treated conditions to improve mechanical properties. The first stage of a T6 temper is solution treatment at an elevated temperature, generally in the range of 480 - 540°C. After solution treatment, the cast part is typically quenched in water/air to retain the solute-rich homogeneous matrix chemistry at room temperature. Subsequent ageing treatment stages capitalize on this super-saturated solid solution to generate controlled dispersions of very small strengthening precipitates within the matrix of Al grains [l]."

Jan 1, 2013

By Gavin Lind

The Minerals Council of Australia (MCA), through its Minerals Tertiary Education Council (MTEC), builds capacity in higher education in the core disciplines of mining engineering, metallurgy and minerals geoscience. Over the past fourteen years, this all-of-industry approach in securing the long-term supply of these critical skills (which remain a chronic skills shortage for the Australian minerals industry) through nationally collaborative programs across sixteen Australian universities delivers spectacular and sustainable results for the industry. These unique, world-first programs are built on a healthy platform of dedicated industry funding and in-kind support and forms part of the MCA’s broader uninterrupted, sustainable education and training pathway to increase workforce participation, workforce diversity and workforce skills, regardless of the business cycle in the industry. This paper will highlight the origins, iterations and current successful programs of MTEC, including its future vision, and presents a mechanism for industry and academia to collaborate to address future professional skills needs in the minerals industry globally.

Jan 1, 2014

By J. B. Cocanour

Pioneering work at the U.S. Bureau of Mines (USBM) has produced a personal computer (PC)-based, software-driven video photometric color sensor for real time process control of metallurgical streams. The video photometer is an inexpensive optical sensor which operates in the visual area of the electromagnetic spectrum and collects color information through plastic optical fiber. The red, green, and blue (R/G/B) voltage components of the color video signal are digitized and characterized through software and then presented as the control variable for software-based proportional-integral-differential (PID) control. This sensor has been successfully employed in the control of a laboratory copper electrolytic circuit. With this sensor, copper solutions were analyzed on-line without the need for sample removal, dilution, mixing or reagent addition, thereby allowing for the real time control of the circuit.

Jan 1, 1994

By G. A. Brooks

Increasing interfacial area through gas injection is one of the main methods for accelerating reaction between slag, metals, and gases in modern pyrometallurgical reactors. In slag-metal reactors, the generation of a large number of metal droplets into the slag phase through high gas velocity has a much larger effect on the overall kinetics compared to the enhanced mass transfer through mixing. Top blowing technology generates large interfacial areas (>300 m2/tonne) through high impingement gas velocity at short distances between the exit of the injection lance and the metal-slag interface. Phase separation may become a limit at the case of very high interfacial areas, though there is still only limited understanding of the trajectories of metal droplets in slag-metal-gas emulsions.

Jan 1, 2003

By S. Subhawong

Following the startup of the zinc plant in Clarksville, Tennessee, in 1978, the original effluent treatment plant did not perform as designed. The sludge, produced in a conventional lime neutralization treatment, settled poorly and began to fill the permitted lined impoundment within two years, well short of the original design capacity. Another sludge pond had to be constructed. This led to a new process modification of the original design. Although the design is still based on the conventional lime precipitation of heavy metals, the current effluent treatment plant has evolved into a hydrometallurgical circuit, capable of producing good quality water without generating sludge. Undesirable elements are bled from the zinc circuit and are rejected through the effluent treatment operations. Wallboard grade gypsum is produced, instead of sludge, and all the gypsum is sold to cement and wallboard plants. This operation also recovers and returns more than 1,500 tonnes of zinc annually to the 105,000 tonne/y zinc plant.

Jan 1, 2000

By R. Moreau, V. Uspenski, K. Messadek, Y. Delannoy

Experiments and numerical simulations have been carried out to investigate the properties of quasi-2D turbulence. A new mercury model experiment has been built and tested in a uniform magnetic field up to 6T, (Ha~ 1000), ensuring a better two-dimensional behaviour than earlier versions (Alboussiere et al., 1997), limited to 0.2T. The quality of the experimental results has been improved in order to get wave number spectra (instead of frequency spectra) and higher signal over noise ratio (due to the higher magnetic fields). In parallel, some two-dimensional "direct" numerical simulations were performed using a commercially available code to solve a 2-D motion equation involving a source term to model the Hartmann layer. This term is derived from the condition of closure of the electric current, which allows to transfer the Hartmann effect into the 2D-core flow without simulating the layer itself (Sommeria & Moreau, 1982). No subgrid scale modelling is needed in such a two-dimensional situation where most of the energy is carried by the large scales.

Jan 1, 1999

By Zuomei Jin

A laboratory study was conducted on the separation of Zn, Pb, Cu and Ag from a finely dissem-inated interlocked silver-rich multimetal sulphidc ore. These are often difficult to separate from each other by flotation. The thermodynamic calculations of Zn-S-O, Cu-S-O systems at different tem¬peratures were presented on predominance diagrams. Based on these diagrams the optimum temperature and gas composition were selected for roasting. The results of separating Zn, Cu from calcine by neutral leaching and acid leaching were found to be satisfactory. The distribution of silver in the roasting and leaching processes were tested. A flow sheet was proposed.

Jan 1, 1993

By T. A. George, David J. Sellmyer

"The concept of achieving a useful high-energy-product magnet through appropriate nanostructuring of known hard and soft phases has been tantalizing researchers since the idea was first proposed. The fabrication of exchange-coupled nanocomposite magnets faces several challenges including aligning the easy anisotropy axes of the hard-phase grains. Here we investigate experimentally two-phase nanostructures of hard Lio-ordered FePt and soft iron-rich/cc Fe(Pt). The Fe-Pt thin films were produced by epitaxial cosputtering onto MgO (001) single-crystal substrates which lead to strong (001) texturing. The measured hysteresis loops indicate nearly ideal exchange coupling. Excellent magnetic properties are obtained, with largest values of coercivity (51 kOe), saturation magnetization (1287 emu/ cm3, J, = 16.2 kG), and nominal maximum energy product (58 MGOe).1. IntroductionA key figure of merit for permanent magnets is the maximum energy product (BH)rrw.x. The achievable maximum energy product is determined by a magnet's saturation magnetization M, and its magnetic anisotropy. For example, it is well known that (BH)rrw.x :S 4n2M,2• In the past, record energy products have been the result of discovering new compounds with high values of magnetization and anisotropy. However, finding new compounds with better magnetic properties than the current record-holding magnet Nd2Fe14B has proven to be difficult. A different approach is to exploit the exchange coupling mechanism between known hard and soft magnetic phases to enhance the maximum energy product [1-5]. In such a composite system, high coercivity is achieved due to the anisotropy of the hard phase as well as a nanostructure which prohibits large-scale domain wall reversal mechanisms. Magnetization is enhanced by the soft phase and loop squareness results from texturing of the hard phase easy-axis as well as complete exchange coupling between the coexisting hard and soft grains."

Jan 1, 2012

By Satoshi Itoh

Phase equilibria and activities of the components in the liquid lead-antimony-oxygen ternary system, which is of fundamental importance for discussing the' recovery of lead and antimony from a used lead-battery, have been investigated at 1173 and 1223 K. The two liquid phases of metal and oxide were observed at the temperatures studied, and the tie lines indicating isoactivities were determined. The activities of PbO, SbO1.5 and Sb2O3) in the PbO-SbO1.5 and PbO-Sb2O3 pseudo-binary systems were then obtained by applying the Gibbs-Duhem equation to the phase relation of metal-oxide equilibrium. Both in the pseudo-binary systems the activities exhibit negative deviations from Raoult's law. The vapor pressures of lead, antimony and lead oxide, antimony oxide were calculated by using the activities of the components in the lead-antimony-oxygen ternary system. As a result, an oxidation of antimony concentrated in an anode slime followed by evaporation as antimony oxide Sb406 was found to be considerably effective for the recovery of lead and antimony from a used lead-battery.

Jan 1, 2003

By Jun Miao, Kang Liu, Jilai Xue, Jun Zhu

CO2 emissions must be reduced by at least 50 % by 2050, and hence the technical solutions to capture and convert CO2 into value–added products should be considered. A Cobalt(III) Schiff base complex (Salen–Co(III)) has been investigated as a catalyst for synthesis of cyclic carbonate from CO2 and epichlorohydrin(ECH) with tetrabutylammonium bromide (TBAB) as co–catalyst. To recover Salen–Co(III) for the next cycling operation, it was immobilized onto zeolite 13X through excessive impregnation method. The immobilized catalyst was characterized using XRD, SEM, BET and ICP–AES techniques. Catalytic tests showed that yield of cyclic carbonate reached 90 % using 0.5 mol % Salen–Co(III) at ambient conditions. The immobilized Salen–Co(III) exhibited better catalytic activity than the homogenous one when used at the first cycle, but the yield decreased by some 20 % after five cycles.

Jan 1, 2015

By Satoshi Itoh

Phase equilibria and activities of the components in the liquid lead-antimony-oxygen temary system, which is of fundamental importance for discussing the recovery of lead and antimony from a used lead-battery, have been investigated at 1173 and 1223 K. The two liquid phases of metal and oxide were observed at the temperatures studied, and the tie lines indicating isoactivities were determined. The activities of PbO, Sb015 and Sb203 in the PbO-SbOu and PbO-Sb203 pseudo-binary systems were then obtained by applying the Gibbs-Duhem equation to the phase relation of metal-oxide equilibrium. Both in the pseudo-binary systems the activities exhibit negative deviations from Raoult's law. The vapor pressures of lead, antimony and lead oxide, antimony oxide were calculated by using the activities of the components in the lead-antimony-oxygen ternary system. As a result, an oxidation of antimony concentrated in an anode slime followed by evaporation as antimony oxide Sb406 was found to be considerably effective for the recovery of lead and antimony from a used lead-battery.

Jan 1, 2003

By Julien Favre, Akihiko Chiba, Damien Fabregue, Yuichiro Koizumi, Eric Maire

"The mechanical behavior of Co-20Cr-15W-10Ni alloy is studied by compression tests at high temperature. Microstructures after deformation are evaluated using SEM-EBSD. Significant grain refinement occurs by dynamic recrystallization for high temperature and low strain rate (T>1100°C, <0.1s-1), and at high strain rate (~10s-1). Dynamic recrystallization is discontinuous and occurs by grain boundaries nucleation, leading to a necklace structure. The nucleation mechanism is most likely to be bulging of grain boundaries. However, recrystallization occurs also by rotation of annealing twins which can bulge as well. The modeling of mechanical behavior gives a fair quantification of flow softening due to dynamic recrystallization, indicating the progress of dynamic recrystallization with deformation.IntroductionCobalt-chromium alloys are used in biomedical applications for the elaboration of implants due to their outstanding mechanical properties and their high resistance to corrosion. For stent application a large ductile behavior is required in addition to the high mechanical strength. Indeed stents have to undergo a deformation until e˜40% during their expansion [1]. Conventional Co-Cr-Mo (CCM) alloys exhibit limited ductility (maximal deformation about e˜30%) [2]. Co-Cr-W-Ni (L-605) alloy is a better candidate for stent elaboration since its fracture strain can exceed 40% (comparable to nickel superalloys (Figure 1), while it keeps high mechanical strength. In spite of the presence of nickel element in this alloy, biocompatibility is sufficient for vascular implants, therefore L-605 alloy is extensively used for heart valves and stent elaboration [3]."

Jan 1, 2012