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By Florian Kongoli

The liquidus surface of multicomponent slags is an important parameter in various smelting and converting processes. It helps not only to optimize the slag, chemistry of current processes and their fluxing strategies, but also to determine the availability of new slags for more advanced technologies. In a series of our previous publications, the liquidus surface of some multicomponent iron oxide slags has been quantified at several constant oxygen potentials and the effect of the latter, ignored until that moment, was quantified along with the effect of some minor components. In this work, the liquidus surface of some iron oxide slags is quantified at constant CO2/CO ratios. This is a new convenient way for the quantitative description of the slag liquidus surface and the effect of several fluxes, especially in those processes such as slag solidification, where oxygen potential changes continuously. This type of diagram also describes more dynamically the effect of oxygen potential, clarifies the relation between CO2/CO ratio and oxygen potential in terms of the liquidus surface, which is not widely understood by metallurgist today, and reduces the gap between laboratory work and industrial experience.

Jan 1, 2002

By K. Ono

A new process for extraction of titanium metal from its oxide is demonstrated. In this process, row material to be reduced is titanium oxide synthesized from ilmenite. The reducing agent is the Ca+CaCI2 two-phase mixture. TItanium is elaborated in the medium consisted of liquid Ca, Caq and solid TI02 at the temperature range 1200 to l300K by means of mixing mechanically the ingredients in the reactor into a smooth paste. Fluidity of the feed which enables continuous scheme depends on the CaCl2 content. The oxygen level of the reduced titanium is the range 500 to 1000 mass ppm varying with the operational conditions. The Ca+CaCI2 reducing agent is taken out from the electrolysis of CaC12 at 11401(, and this CaCl2 is produced by aqueous chemistry conversion using Cl2 gas recycled from the electrolysis.

Jan 1, 2001

By Allan J. MacRae

A copper alloy to be used for coils in cast copper cooling blocks has been identified and samples prepared for metallurgical examination and destructive testing to compare with cast cooling blocks manufactured from copper and nickel-copper alloy pipes. The copper alloy allows for the formation of a metallurgical bond between the pipe and the cast copper during the casting process, which does not normally occur with pure copper or nickel-copper alloy pipes. The alloy's coefficient of thermal expansion is also much closer to that of pure copper compared with nickel-copper alloys, so there is less strain induced at the pipe-cast copper interface due to differential thermal expansion. It is expected that this new pipe coil alloy and associated casting techniques will allow for the production of cast copper cooling blocks that have greatly enhanced service life in high heat load applications compared to existing technologies.

Jan 1, 2002

By R. Winand, M. Degrez, C. Temmerman

"The influence of the copper electro crystallization inhibitors (mainly thiourea, gelatin and chloride ions) is studied in a new fully automatic pilot plan. This paper describes the conception and the building of this plan. The new approach is to reproduce the experimental conditions observed in the industry with the three additives present simultaneously in the electrolyte and secondly to study the influence of a slight modification of the concentration of one inhibitor, the others being present in the electrolyte with their industrial nominalconcentrations.1. INTRODUCTIONDespite the fact that gelatine, thiourea and chloride ions have been used in copper electrorefining for a long time, precise knowledge concerning their influence on the cathode deposit, metallographic structure and associated properties is still lacking.Many authors studied the influence of each additive separately, or of two added at a time. Only a few authors studied the combined influence of the three additives added simultaneously. The general conclusion that can be drawn is that the combined influence is far from that forseen from the influence of each additive separately, or even from two additives used at a time. Moreover most of the experiments described in the literature were performed by adding all additives at once initially. It is however, well known that gelatine looses a great part of its activity during the first half hour due to degradation by sulfuric acid (as shown by the cathode overpotential drop). Thiourea is rapidly replaced by a number of degradation mole,cules and complex ions including cations from the solution, changing even the equilibrium between Cu, Cu(I) and Cu(II).Chloride ions are consumed by precipitation.A number of successive research projects [1-9] led pregressively to the concept that, in order to obtain reproducible results representative of industrial cathodes, it was necessary to simulate as far as possible industrial conditions. It was essential that all additives were added continuously during the electrolysis, with, as consequence, a continuous bleed.The purpose of this paper is to describe the concept of a new fully automatic pilot plan for copper electrorefining and to present the first results."

Jan 1, 1997

By M. Radwan

This research reports on the synthesis of advanced silicon-based structural ceramics from mixtures composed of natural sand (Sinai white sand), reclaimed silicon and graphite by the nitriding combustion synthesis method. With pulverized sand (? 40 m), we found that the nitriding combustion can be realized at self-sustaining mode in the SiO2?Si?C system under 3 MPa nitrogen pressure. Depending on the composition of the starting mixtures, single-phase silicon oxynitride (Si2N2O) powder as well as new Si3N4?Si2N2O and Si2N2O?SiC composite powders with controllable chemical compositions were successfully developed. The measured thermograms of various combusted mixtures and the thermodynamic characteristics of possible exothermic reactions in this system were discussed to explain the nitriding combustion behaviour and mechanism. Near-full dense Si2N2O were fabricated from synthesized Si2N2O powder with 5 wt % oxide additive by the spark plasma sintering (SPS) method at 1600 °C. The dense Si2N2O samples had good mechanical properties (18.7 GPa Vickers hardness, 3.3 MPa m1/2 fracture toughness and 363 MPa strength) and excellent chemical and oxidation resistance. The synthesized composite powders were also densified to high densities (> 90 % of theoretical values) by SPS technique. The results obtained in this study can be seen as a new route to prepare important silicon-based structural ceramic powders with various compositions/properties from cheap starting materials which makes them potential for wide range of applications.

Jan 1, 2006

By C. Lupi

Zinc chloride electrowinning presents difficulties in obtaining smooth, compact and dendrite free deposits with a high current efficiency due to the presence of undesirable metal ions. However, it is hard to define a level of impurities tolerable in zinc deposition, and despite a lot of research in this field, the reaction mechanisms of the undesired metal ions are still not clearly understood. In this study, the influence of Fe, Cd, Co, Ni and Cu additions were investigated, as well as their synergic effect on the zinc electrodeposition process from chloride electrolytes and on the obtained deposit morphology. The tests were all performed in presence of TBACl which reduces the harmful effect of such impurities on the zinc reduction.

Jan 1, 2003

By Anjali Talekar

Low temperature heat capacities of pentaerythritol [PE: C(CH2OH)4], pentaglycerine [PG: (CH3)C(CH2OH)3], and 2-amino-2-methyl-1,3-propanediol [AMPL: (NH2)(CH3)C(CH2OH)2]have been determined by adiabatic calorimetry from 3 K to 300 K. To the best of our knowledge, this is the first reported heat capacity measurement below 280 K for PE and AMPL. The Debye temperatures for these organic crystals have also been determined and compared with other alcohol derivatives of neopentane.

Jan 1, 2006

By Ann M. Hagni

Electric arc furnace (EAF) dust from the secondary steel industry contains lead, cadmium, and chromium that causes it to be classified as a hazardous waste. Pyrometallurgical treatment of EAF dust is directed at recovering zinc and simultaneously rendering the dust non-hazardous. The mineralogy of the EAF dust is important in determining the occurrence and phase relationships of the zinc, lead, cadmium, and chromium contents. The principle phases in EAF dust as determined by reflected light microscopy, SEM-EDS, and XRD are solid solutions of the iron spinels (franklinite, magnetite, and jacobsite), zincite, hematite, and Ca-Fe-Si glass. Chromium is present in small amounts in solid solution in the spinels. Cyclone sizing of the minus 53 pm particles shows that more than 50% of this size fraction are less than 10 pm in diameter. The <I0 pm particles contain zinc as both franklinite in solid solution with magnetite and jacobsite, and zincite as determined by transmission electron microscopy and XRD. Auger electron spectroscopy did not detect coatings of volatile phases on the surfaces of EAF dust particles.

Jan 1, 1994

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 Khosrow Nikkhah

Increasingly ion exchange systems are being included in design of hydrometallurgical plants for metal extraction or impurity removal. Because such systems operate sequentially and are based on resins that exchange one ion for another, store it temporarily and release it to a regenerating solution, the usual steady state heat and mass balancing tools and spreadsheets cannot be used to design them successfully. This paper outlines the role of dynamic simulation in design of ion exchange systems. Examples are given for use of dynamic simulation in design and investigation of equipment based on consideration of the effect of input criteria such as expected ion loading and elution profiles. The methodology for dynamic modeling using IDEAS in design of multi column ion exchange trains operating in parallel is presented. Results shown include the non-steady state distribution of extracted metal and limitations imposed on operating conditions. These conditions include proposed sequencing of columns for loading and elution cycles, loading, elution and recycle flow rates as well as size and choice of related ion exchange plant equipment.

Jan 1, 2003

By R. M. Donovan

This paper documents the efforts to improve quality and production at the Amarillo Copper Refinery. It summarizes the change in attitudes, work procedures, equipment maintenance, instrumentation, and the ever changing market. The Amarillo Copper Refinery is dedicated to the ASARCO Management System, ISO-9002 and continuous improvement.

Jan 1, 1999

By Deming Wang, R. A. Overfelt

"This paper presents a computer-aided heat transfer simulation method to predict the thermal characteristics of an alloy sample in a special furnace for directional solidification. A two-dimensional transient heat transfer by conduction combined with radiation is developed to calculate the energy exchange between a directional solidification furnace and the sample. Finite difference equations with control volumes are used to calculate the transient heat transfer. A special boundary control volume is used to combine heat conduction and radiation in the transient heat transfer. Heat radiation effects on the surfaces of the special control volumes with a changeable view factor during directional solidification processing are also represented. The simulation results are verified by measurable experimental data. Using the computer simulation model, many thermal properties of the directional solidified castings can be obtained, such as temperature distribution, solidification velocity, the shapes and positions of the liquid/solid interface and thermal gradient at the interfaces. These are very important to analyze microstructure of casting alloys, avoid casting defects and control casting quality. 1 IntroductionIn directional solidification (DS) processing of castings, the temperature distribution, the interface between liquid and solid zone, thermal gradient in the mushy (pasty) zone and solidification rates are very important factors to analyze the microstructure and the casting quality. These variables affect the orientation and size of dendrites, shapes of grains, solute segregation and deleterious casting defects, such as microporosity, freckles and segregation channels. In order to avoid the casting defects, the temperature distribution and thermal gradients of castings during directional solidification must be strictly controlled. However, the structure of furnaces used for directional solidification is often complex. Heat transfer and temperature distribution within a casting not only depend on furnace temperature but also on the thermal properties of the casting alloy, crucibles, retorts etc. A more accurate heat transfer analysis."

Jan 1, 2001

By W. G. Davenport

Chapter 11 determined the combinations of industrial oxygen, oil and blast preheat that will steadily produce 65% Cu matte from pure chalcopyrite concentrate. It showed that the . combinations are described by a flat plane. It also showed that the minimum energy requirement for making 65% Cu matte occurs with maximum oxygen enrichment, zero oil and zero blast preheat. This chapter examines the, effect of matte grade on industrial oxygen, oil and preheat requirements.

Jan 1, 2001

By Gerald K. Vellente

Producers of strip coated products are being approached by users to supply higher quality products and adhere to tighter specifications. Suppliers, in an attempt to assist the producers, must consider new technologies for equipment. In the past several years, the induction melting and heating industry has made great strides in developing new and innovative equipment, while improving existing technology. In the past several years, the induction melting and heating industry has made great strides in developing new and innovative equipment, while improving existing technology. In the past several years, the induction melting and heating industry has made great strides in developing new and innovative equipment, while improving existing technology. This paper will review recent developments to include improved refractory systems for ceramic pots, new channel-type inductors which are more efficient, new power control systems for existing channel-type pots, and innovative use of multi-purpose lines. Additionally, new heating applications such as galvannealing, edge heating, and post heating will be reviewed. Advanced math models for controlling heat will be discussed. Producers can easily meet the demands of their customers because of the flexibility provided by the equipment reviewed.

Jan 1, 1992

By Ronald Klepper

In hydrometallurgy, pure gases like oxygen and hydrogen are used for oxidation and reduction. The gases are expensive and therefore should be used efficiently. Non reacted gas can be recycled into the liquid. Historically vortex gassing has been used; Le. a mixing impeller close to the liquid surface entrains gas from the headspace into the liquid through a gas vortex. Novel and more efficient methods are surface gassing with up pumping impellers and self- inducing gassing impellers. These alternative impeller systems are well established and common in the chemical industry, but have not been used until recently in hydrometallurgy. Gassing impellers act as internal compressors and increase the interfacial surface for a much higher mass transfer compared to alternate methods mentioned. In the paper results from lab and pilot tests and data from operated plants will be presented. The reactions with gases normally take place under moderate to high pressure, therefore a safe enclosure with mechanical seals and the safety "philosophy" is important. Experienced life and replacement cycles will be reported.

Jan 1, 2000

By David Bequette, Ray D. Peterson, Cynthia K. Belt

"With a need to cut production costs in the metals industry, cost savings from energy efficiency improvements are critical. Opportunities can be found by reviewing furnace systems and practices so that the melting and holding processes operate at the highest energy efficiency. Many of the changes can be implemented with a minimum of expense or capital investment. This paper will review several low cost methods to optimize energy efficiency on reverberatory melting or holding furnaces. These five methods (furnace utilization, idle procedures, fire rate, controls, furnace pressure) will be explained and information given to implement these changes. Included are several rules-of-thumb and benchmarks for aluminum reverb furnaces.IntroductionEnergy can be a significant portion of the total manufacturing costs for metals and materials manufacturing involving thermal processing such as heat treating, melting, and high temperature processing. Natural gas prices have dramatically varied over the last few years. While no one can foresee the future, prices are expected to increase from the current low prices. More recently, emphasis is being put on the reduction of greenhouse gases with the potential of additional costs to industry.One of the first steps in an energy management program is to measure the energy usage of the process [1]. The results are typically understood in relation to the mass melted in kWh / mT [BTU / lb]. For the purposes of this paper, furnace energy efficiency is calculated over a month or even a year and thus includes hold times. This efficiency is typically different from the values quoted by furnace manufacturers. Those values are for limited short term tests at highutilization.Once you know the performance for your furnaces, these should be compared to industry benchmarks. For aluminum melt furnaces with cold air burner systems, a benchmark value or goal is 1800-2000 BTU/lb [1160-1290 kWh/mt], though some of the best have reached 1600 BTU/lb [1030 kWh/mt]. Furnaces with regenerative burners can attain 1100-1200 BTU/lb [710- 775 kWh/mt]. There are some designs of multi-chamber furnaces or oxygen furnaces that have improved on these numbers, perhaps as low as 950 BTU/lb [615 kWh/mt]. Typically, as the degree of sophistication and energy efficiency of the furnace increases, so does the cost."

Jan 1, 2010

By Michael S. Moats, Daniel Kim, Shijie Wang

"The behavior and deportment of lead, arsenic, antimony and bismuth are critical in producing high quality cathode by copper electrorefining. A critical review of research related to these elements is presented along with a comparison to industrial data, where appropriate. These elements exist predominantly in the anode as complex oxides along die grain boundaries. Upon dissolution, Group 15 elements report both to the electrolyte and slimes while lead essentially enters the slimes. The deportment of the Group 15 elements appears to be influenced by several chemical interactions which are discussed. The effect of these elements on floating slimes and anode passivation is reviewed. Under normal electrorefining conditions, lead, antimony and bismuth are thought to enter the cathode through the encapsulation of slime particles. The literature indicates that arsenic enters the cathode predominately by electrolyte entrainment. Finally, areas for future research regarding these elements are presented.IntroductionControlling lead, arsenic, antimony and bismuth is critically important for the production of high quality cathode in copper electrorefining. The reasons for this are twofold. First, ASTM Grade 1 Cathode specifications [1] for these elements are low, as listed in Table 1. Second, they can affect the efficiency of the electrorefining process (e.g., through passivation, current efficiency, slime processing)."

Jan 1, 2012

By David Roha, Øyvind Mikkelsen

"Significant resources have been spent throughout the years in the investigation of production of aluminum by carbothermic reduction. Due to the technological challenges involved, the efforts have not yet resulted in a commercial process. An initiative to overcome issues that prevented previous attempts to succeed was taken by Alcoa through the Advanced Reactor Process. The research program has resulted in technical developments which have resolved many of the previous issues. The knowledge about the process has continuously improved through physical and computer modeling as well as by experimentation at various scales. The technical achievements together with improved process understanding have resulted in a reactor design able to continuously operate the process for several weeks at the time, with hundreds of kilograms of alloy in every tap.IntroductionThe Hall-Heroult process has since its invention in the late 19th century, been essentially the only process used for commercial production of primary aluminum. The process has so far proved to be superior to all potential process alternatives and has continuously been improved. Although the Hall-Heroult is a reliable process it also has challenges:"

Jan 1, 2012

By Huasheng Chen, Gaifeng Xue, Jing Zhang, Mingsheng He, Bin Liu, Yexian Ouyang, Shoujun Peng

Based on the investigation and study of the topography, microstructure and composition of the buildups which form in the surface of carbon sleeve in continuous annealing furnace for lowand medium-grade non-oriented silicon steel produced by CSP process, combined with production process of silicon steel, the mechanism and major causes for forming buildups of carbon sleeve are discussed from the factors such as CSP process, the quality of carbon sleeve and so forth. Meanwhile, some countermeasures to reduce the formation of the buildups are put forward.

Jan 1, 2015

By M. Sizgoric

Certain types of mineralogical alteration due either to weathering or serpentinization, and the effects these transformations have on the flotation of nickel sulfide ores are discussed. These effects are generally deleterious due to: (a) the poor flotation properties of the alteration minerals (as in the case of tochilinite), (b) the nature of the alteration texture (as in the case of violarite), or (c) .close association of the alteration products with other undesirable minerals (such as nickeliferous smythite). Several examples from INCO Metals Company&apos;s mines and mineral prospects are given as illustration.

Jan 1, 1981