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By K. Santowski, S. B. Breyner, T. Prietl

"The material properties of alumina products can be significantly improved by adding Cr203 containing raw materials. Cr203 and Alz03 form an alumina-chromia solid solution during firing, reducing the solution potential when in contact with acidic slags. During service, both a high chemical and high thermomechanical load are present for example in the tuyere zones and taphole areas of metallurgical vessels. For such applications conventional alumina-chromia products suffer from discontinuous spalling as a result of high and frequent thermal shock. Therefore, alumina-chromia materials were developed that exhibit improved thermal shock resistance, compared to the standard products, combined with sufficient corrosion resistance. Laboratory tests evaluated the physical properties of the newly developed alumina-chromia grades and a field test in a Peirce-Smith copper converter demonstrated that the material properties meet the corrosion and thermal shock resistance required for this application. IntroductionTo develop refractory products tailored to specific service conditions it is important to have a profound knowledge of the metallurgical processes and furnace conditions [l]. This enables the specific refractory consumption to be minimized and increases the overall operational efficiency. Economic considerations such as steadily increasing energy and resource costs have resulted in companies investing in recycling processes. In the base metal industry for example, recycling operations involve modifications to the smelter feed, process conditions and chemical composition of the process slags. This adversely affects the performance of standard linings and drives refractory producers to search for material innovations."

Jan 1, 2013

By Mike Santaluce

Smelting furnace rebuild projects often require a significant capital expenditure and an extended smelter outage. Smelter operators are increasingly searching for methods and initiatives to shorten furnace rebuild schedules, maintain manageable cost levels, enhance furnace performance and achieve excellent safety results. This paper describes the ?MEPC? Model for furnace rebuilds; a project driven approach which Auburn has developed in response to the need for improving furnace rebuild project outcomes. The ?MEPC? (Management, Engineering, Procurement and Construction) approach better addresses the unique challenges presented by furnace rebuild projects when compared to the traditional EPCM (Engineering, Procurement, Construction Management) model widely in use for these projects today. One key feature of the MEPC model is that a dedicated project management team with representation from all of the major project stakeholder groups is put in place at the onset of the project. The project management team has ownership and accountability for meeting overall project goals over the entire lifecycle of the furnace rebuild project. A second key aspect of the model is emphasis on project management as a completely separate project function with its own specific skill sets, techniques, tools and best practices. These features of the MEPC model offer several advantages in terms of improved planning, coordination, communication and alignment with project goals which contribute to the overall success of furnace rebuild projects. Similar MEPC concepts have been used to deliver excellent project results in other industries and the MEPC approach has been successfully utilized on furnace rebuild projects.

Jan 1, 2006

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By Md Sazzadur Rahman

Electrochemical Impedance Spectroscopy studies were conducted on two organic thermal energy storage materials; Neopentylglycol (NPG) and 2-Amino-2-Methyl-1,3-Propanediol (AMPL). The ionic conductivities and dielectric relaxation times in the low temperature ordered a-phase (monoclinic for both NPG and AMPL) as well as high temperature orientationally disordered cubic y-phase are reported.

Jan 1, 2006

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By John O. Marsden

The past fifteen years have seen a number of important developments in copper hydrometallurgy, including the commercial application of biological heap leaching of secondary (chalcocite-dominant) copper ores, the commercial demonstration of chalcopyrite concentrate leaching technology using pressure leaching and biological processes, and the application of novel configurations of solution extraction circuits. Significant emphasis is now being placed on the development of effective stockpile leaching practices for primary ores (chalcopyrite and bornite-dominant mineralization). Some of these developments have been highly successful, and will pave the way for further development and commercialization. Others have been less successful. These developments are reviewed in the context of the metal price cycle and trends for the future are identified.

Jan 1, 2006

By Alana Pereira Ramos, Walman Benicio de Castro

Amorphization and martensitic transformation (Ms) characteristics of Ti–Ni-Cu alloy ribbons prepared by melt spinning were investigated by means of differential scanning calorimetry and X-ray diffraction. In these experiments particular attention has been paid to change the wheel linear velocity from 21 to 63 m/s. Then the cooling rates of ribbons were controlled. The effect of this cooling rate and alloy composition on martensitic transformation behavior is discussed.

Jan 1, 2015

By T. R. A. Davey

It is often important in the study of a process to determine whether the limitations are governed by equilibrium or kinetic considerations. Sometimes it is possible to devise a design of the process or the equipment so that the apparent. limitations set by equilibrium considerations are overcome. In this paper, detailed consideration is given to the lead refining processes of sulfiir-decoppering and of vacuum dezincing to illustrate this, and possible implications for other refining processes are indicated.

Jan 1, 2000

By Kang-In Rhee

Nonferrous metal recycling not only provides energy saving and environmental benefits but also is a significant factor in the supply of various types of metals used in our society. Recycling plays an important role in establishing the sustainability of materials. The total amount of recycled nonferrous metals by weight accounts for less than 5% but their value is larger than 50% compared to ferrous metal recycling which consists of about half of the total metal recycling in weight. This paper describes trends and typical achievements in nonferrous metal recycling and overviews the present and future of nonferrous metal recycling technology and business in Korea.

Jan 1, 2006

By Milind Deo, Neale R. Neelameggham

The mixture of carbon dioxide and water vapor - called Soda [as in carbonated water] can be converted to easily stored transportation fuels. Earlier papers on Soda- fuel metallurgy noted that this conversion is endothermic requiring energy. Reduced state metallic elements - preferably the alkali, alkaline earth elements, or aluminum can act as oxygen carriers. Availability of such a combination in commonly land fille waste materials is shown. Plant based wastes which are normally composted form a better-controlled reagent. The energy required for the reaction can come from solar energy. This paper describes possible reactor designs, which can accommodate this conversion effectively using carbon dioxide recovered from flue gases.

Jan 1, 2008

By Sergio Demetrio

Over a period of nearly a hundred years throughout this century, the company direction and management of copper smelters in Chile has evolved from one characteristised by a paternalistic, autocratic style to one which empowers the local management team and people for running the smelter as a successful business. This paper discusses the evolution of the present style of management amidst changes in the Chilean Government, the mining industry and society since the beginning of this century.

Jan 1, 1999

By Xu Zhong

The theoretical limit to smelting rate and possibly the size of a smelter is dependent on the rate of heat transfer, and the chemical kinetics of both sulfur removal and minor element volatilization. The fundamental kinetics of volatilization of minor elements such as As, Sb, Bi, and Pb from matte and white metal is being investigated. It has been shown that the molecular form of trace elements in matte depends on the chemical potential of sulfur and the propensity for the minor element to form a sulfide. The impact of the variable molecular form of the minor elements on the volatilization kinetics is unknown and is under investigation in this study. The experimental technique is reviewed and preliminary results are reported in this manuscript.

Jan 1, 1995

By David B. George

In spite of the many well-known problems inherent in Pierce-Smith converting, it remains the dominant copper converting process. Continuous copper converting and direct concentrate to blister smelting have been commercially available for over 25 years and now produce approximately 15% of copper smelter production. The two fully commercialized continuous converting processes, Mitsubishi MI Process and Kennecott-Outokumpu Flash Converting, and several emerging converting processes are reviewed with view of their potential, limitations, and environmental performance. Some myths regarding these technologies and Peirce-Smith converting are also challenged.

Jan 1, 2002

By M. F. Chambers

Neodymium metal was electrowon from a molten-chloride electrolyte at 650° C using a molten-metal cathode. A 50 mol pct NdC13-50 mol pct KC1 mixture served as the electrolyte. Binary metal alloys of 'Mg with Zn and Mg with Cd were used as molten cathodes. Under the best conditions, current efficiencies were 90 pct with a Mg-Zn cathode and 80 pct with a Mg-Cd cathode. Vacuum distillation was performed at 1,100° C for 30 min under a vacuum of 10-3 to separate the cathode metals from the neodymium. Neodymium metal of 99.9+ pct purity was recovered from the Mg-Cd alloy cathode. Almost 2 pct zinc remained in the neodymium recovered from the Mg-Zn alloy.

Jan 1, 1989

By Jin Liu

The mechanism and rate of carbon reduction of each of the phases that are formed in the flash flame, i.e. sulfide (matte) and oxysulfide, was investigated. Graphite-slag reduction was conducted for comparison purposes. The objective of these tests was to measure the rate of solid graphite reduction of respectively matte, oxysulfide, slag, and matte+slag mixture at different temperatures. More in particular, these tests were expected to permit understanding and explaining the reduction mechanism of each material by comparing the respective reaction rates, product reaction gas compositions and CO/CO2 ratios, reduced material assays, activation energies, and other relevant parameters. Direct visual inspection of the test crucibles would provide additional information.

Jan 1, 2006

By Hazoor Singh Sidhu

Materials degradation due to corrosion is the major problem in power generation equipment, gas turbine, fluidized bed combustion, industrial waste incinerators etc. Some super alloys have been developed, but they are unable to have different properties to meet the demand of today?s industry. Therefore, a composite system of a base material providing the necessary mechanical strength with a protective surface layer different in structure and/or chemical composition can be an optimum choice in combining material properties. Thermal spray coating of the components before they put into service by suitable surfacing alloy and with suitable coating method can increase the life of these components several fold. Choice of right coating method and alloy for a particular application is extremely important to get the desired service life. The corrosion of some materials and the role of HVOF thermal spray coatings to counteract the same have been reviewed, with an aim to understand the phenomena along with various applications.

Jan 1, 2006

By Michael J. Nicol

One of the preferred methods for the recovery of gold from refractory gold ores and concentrates involves pressure oxidation in acidic solutions. The main refractory gold-containing minerals are pyrite and arsenopyrite and there is evidence that the presence of even small amounts of chloride can inhibit the oxidation of these minerals and also substantially reduce the recovery of gold. In this paper, the results of a study of the anodic (oxidation) and cathodic (reduction) behaviour of pyrite electrodes in acidic sulfate solutions containing ferric ions at different chloride concentrations and temperatures up to 200oC and pressures of 2000KPa are presented. The electrochemical studies have been complemented by pressure oxidation experiments on a refractory gold concentrate. Results have shown that, as the chloride concentration increases, the anodic reactivity of pyrite is largely unaffected but the rate of the cathodic reduction of iron(III) decreases. The rate of oxidation of a sulfide concentrate and the recovery of gold by cyanidation of the residues decreases at high concentrations of chloride.

Jan 1, 2003

By Toshihide Takenaka

Improvement of corrosion resistance of Mg metal by addition of rare earth metal (RE) was studied, and the effect of surface oxide layer with RE was investigated. The corrosion resistance of Mg was remarkably improved by adding a small amount of RE, and the suitable RE content was clarified. The corrosion resistance of Mg was particularly bettered by conversion coating using a solution including both RE(NO3)3 and Mg(NO3)2. This result indicates that the surface oxide layer consisting of both Mg and RE gives good corrosion resistance to Mg metal. In this study, direct electrodeposition of Mg metal containing RE was also tried in molten chloride with RE chloride, and it was shown that electrolysis could be performed stably. The RE content in the deposited Mg metal was depended on the concentration of RE chloride in the bath and the cathode potential, and Mg metal containing the suitable RE content for its corrosion protection was obtained easily by direct electrolysis.

Jan 1, 2006