Search Documents

By Victor Raul Alarcon

The Ilo Refinery was commissioned in 1975, with a cathode production capacity of 150,000 tpy. In 1994, Southern Perú Copper Corporation (SPCC) purchased the Refinery from Minero Perú SA. Subsequently, in November 1999, Grupo Mexico acquired control of Southern Perú. The anode production facility is located at the Ilo Refinery. A number of effective operating and quality control practices have been developed that have improved anode quality, as well as increasing anode production capacity to 350,000 tpy. These, and other optimization actions have allowed for a current density increase from 213 A/m2 to 275 A/m2, while maintaining current efficiency at 98% and sustaining the high quality of the cathode. The paper will outline the scope of operational practices in the Anode Plant and provide some discussion on the Ilo Smelter modernization project, and the resulting impact on the existing anode plant.

Jan 1, 2005

By P. N. Anyalebechi

The effects of solidification rate on the cast microstructures of aluminum alloys 6009 and 6016 have been investigated with directionally cooled laboratory-size ingots, at 0.2-10.1 K/s and 0.4- 23.1 K/s, respectively. These ranges of solidification rate are within those observed in commercial-size ingots. In both alloys, the average dendrite cell size and second phase particle size decreased with increase in average solidification rate and with a decrease in average local solidification time. However, at comparable solidification rates, the dendrite cells and second phase particles are finer in the shorter freezing range alloy 6009 than in the longer freezing range alloy 6016. This is provisionally attributed to the earlier formation of second phase intermetallics at higher temperatures during solidification and to the formation of greater amount of the relatively coarse plate-like ß -phase (Al9Fe2Si4) phases in alloy 6016. In general, in both alloys, the types and relative amounts of the second phase particles in both alloys are independent of solidification rate.

Jan 1, 2006

By Hector Carreon

Due to elevated temperatures, excessive stresses and severed corrosion conditions, turbine engine components are subject to creep processes that limit the components life such as a turbine bucket. The failure mechanism of a turbine bucket is related primarily to creep and corrosion and secondarily to thermal fatigue. As a result, it is desirable to assess the current condition of such turbine component. By using eddy current images, it was shown that the eddy current technique could be used to monitor creep damage in a nickel base super-alloy. The eddy current results also show a significative variation in the electrical conductivity on the creep damage zone with respect to the background zone in nickel-base super-alloy samples. In addition, the absolute thermoelectric power coefficient show also a strong dependence associated with creep damage in nickel base super-alloy samples using a copper hot tip reference. The eddy current and thermoelectric power techniques seems to show promise as nondestructive evaluation tools for monitoring the level of creep damage in metallic alloys.

Jan 1, 2010

By Mishark Nnabuchi

A heterojunction of PbS - CuS thin film has been grown on glass slides by SGT. The films were annealed for 1hr at temperature of 373K and 423K respectively. The optical properties were characterized using a UNICO UV - 2102 PC Spectrophotometer at normal incidence of light in the wavelength range of 200 - 1000nm. The minimum percentage transmittance was observed to be 34% for sample A and 25% for sample B within the same optical region. The band gap energy was determined from the spectra to be 2.05eV for sample A and 1.85eV for sample B which gave a band shift of 0.20eV. It can thus be concluded that the optical properties of the films within the VIS - UV - NIR can find application in solar thermal technology, particularly as antireflection coating, window materials and as good materials for selective solar cell fabrication.

Jan 1, 2010

By Bowen Li

Silicon Carbide is an excellent refractory material. Its physical properties make it extremely useful, particularly in applications where corrosion resistance and wear are important considerations. Commercial silicon carbide refractory is frequently manufactured by bonding silicon carbide particles with clay; however, clay may cause problems in the sintered products. This study investigates the potential of replacing a portion of the clay with andalusite powder. The results show that micron size andalusite powder can improve not only the strength of the refractory but also the sinterability. The mechanisms for these improvements are discussed.

Jan 1, 2006

By Gábor Csicsovszki

We have developed a novel method - at the laboratory scale - comprising an ion-exchange separation and a membrane-electrolysis step for the purpose of zero-waste regeneration of spent HCl pickling liquors originating from hot-dip galvanizing of common steels. It is aimed at the parallel regeneration of HCl and iron. Experiments revealed that iron can be electrodeposited at high current efficiencies by maintaining the following conditions: 0.04-0.08 M HCl, 500-1000 A/m2, 20°C and stationary electrolyte in a conventional cell. Zinc in the solution did not disturb the deposition of iron, however it contaminated the product and it poisons the anion-exchange membrane required to tackle acidity during electrolysis. For a preliminary separation, anion-exchange tests were carried out to produce pure iron solutions. Beyond the equilibrium studies, column experiments were carried out showing that low flow rates of the loading solution and the ~1.5 M HCl eluent are essential for separation.

Jan 1, 2006

By Alicia Esther Ares

The family of Zn-Al (ZA), Zn-Ag and Zn-Al-Ag (ZINAG) alloys offers high mechanical properties, ease of finishing, the advantage of low energy and pollution-free melting. Also, present alternatives to the well developed alloy systems, such as brasses, bronzes, cast irons and aluminum alloys. The main objective of this paper is to measure thermal parameters in ZA, Zn-Ag and ZINAG hypoeutectic and hypereutectic alloys directionally solidified which present columnar, equiaxed and columnar to equiaxed transition structures (CET). Also, estimate the mechanical properties, such as microhardness and tensile parameters and correlate these with the thermal (cooling rate) and structural parameters (grain size and dendritic spacing). The different types of structures were analyzed with optical and scanning electron microscopy. The results showed the influence of concentration, microstructural arrangement and thermal conditions during solidification on the mechanical properties. The results of the present investigation are compared with previous experiments.

Jan 1, 2010

By David A. Neudorf

Known resources of nickel laterites considerably exceed nickel sulfide resources and there is a growing consensus that most new nickel production will be sourced from laterites. The development of nickel laterite projects is very capital intensive due to inherently low grades, inability to concentrate ore prior to processing, complex processing technology and typically large infrastructure requirements. This has resulted in most recently proposed projects being "mega-projects," to achieve economics of scale. However, this may result in unacceptable project risk in many cases. Furthermore, many known laterite resources are not large enough to support a mega-project. This paper describes an alternative model for nickel laterite project development that allows, smaller scale and reduces capital exposure. The requirements of this model in terms of process technology, infrastructure and commercial innovation are described. Keywords: Nickel, Laterite, Project, Economics

Jan 1, 2004

By David Norval

Ni, Co, Cu and Pt, mattes are common materials that require granulating and milling of the resultant granules for further processing. This route is acceptable if the material is brittle (friable) which is a property associated with the higher sulphur mattes. For lower sulphur levels, where the matte is less amenable to milling, the costs of the milling increases. This paper will compare water granulation with certain dry granulation processes and the downstream processes required for Hydrometallurgy. It will further introduce and expand on atomisation which offers a further safety benefit in the control of the metal flow into the 'wet zone' with the use of a tundish flow control also reducing the conversion from the matte to powder in one fairly straightforward operation.

Jan 1, 2006

By Sutham Niyomwas

Synthesis of alumina-mullite-silicon carbide composite (Al2O3-Al6Si2O13-SiCw) was obtained in situ by carbothermal reduction of a mixture of kaolin and two different silica sources. The carbothermal reduction was carried out in a horizontal tube furnace under flow of argon gas. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the reacting species. The synthesized products were mixtures of alumina, mullite and silicon carbide in the form of whiskers. The effects of adding two different silica sources of rice husk ash and silica powder to the mixture of kaolin and activated carbon were investigated. XRD and SEM analyses indicate complete reaction of precursors to yield Al2O3- Al6Si2O13-SiC as product powders, with the SiC having whisker morphology.

Jan 1, 2006

By Yong-Moo Cheong

When the zirconium pressure tube(PT) is in contact with the calandria tube(CT) in the pressurized heavy water reactor(PHWR), the temperature gradient between the inner and outer wall of the PT results in a thermal diffusion of hydrogen(deuterium) and hydride blisters are formed on the outer surface of the PT. Since Zr-2.5Nb pressure tubes have a high risk for the formation of blisters during their operation in a PHWR, there is a strong incentive to develop a method for the non-destructive detection of the blisters grown on the tube surfaces. However, because there is little mismatch in an acoustic impedance between the hydride blisters and zirconium matrix, it is not easy to distinguish the boundary between the blister and the zirconium matrix with the conventional ultrasonic methods. This study has focused on the development of an ultrasonic method to detect the hydride blisters formed on Zr-2.5Nb pressure tubes. Hydride blisters were grown on the outer surface of a Zr-2.5Nb pressure tube using a cold finger attached to steady state thermal diffusion equipment. Ultrasonic velocity ratio method as well as conventional ultrasonic parameters with an immersion technique was developed to detect small hydride blisters on the Zr-2.5Nb pressure tubes.

Jan 1, 2006

By A. J. Sideris

It is known that Mg can act as a catalyst/solvent in the high pressure high temperature diamond synthesis. However, above pressure levels of the order of 7 GPa, and temperatures from 1700 ? 1800oC, it was not possible yet to use Mg for the industrial production of diamond. A possible alternative is the use of MgNi based alloys. However, owing to the great Mg reactivity, it was consider, so far, a difficult task to deal with such alloys. The present work presents successful results regarding the production of MgNi alloys, with different composition, at high pressure conditions. The behavior of the alloys and their microstructural characterization is analyzed.

Jan 1, 2006

By Nikhil Dhawan

Electronic waste (e-waste) is a collective name given to discarded electronic devices such as Television, Cellular Phones and Personal Computers. Among the heterogeneous metals present in the e-waste are the base metals: copper, aluminium, nickel, tin, zinc, iron and precious metals: gold, silver, palladium, platinum apart from several hazardous and halogens metals. Hence there is a need to recover these metals from electronic scrap by recycling and then re-use, which can meet large amount of metals demand. Hydrometallurgical processing was employed for the recovery of metals from television printed circuit board (TV PCB). Different lixiviants such as hydrochloric acid, Sulphuric acid, and nitric acid were used to understand the dissolution behavior of copper, iron and lead present in the TV PCB. Effect of increasing concentration of nitric acid was also studied. Selective recovery of tin over 95% in the form of tin oxide was precipitated. The precipitated tin oxide was identified by X-ray diffraction technique. Tin oxide of purity more than 99.9% was obtained.

Jan 1, 2009

By Helga Larravide

A new on-line database of literature about copper has been created through a joint undertaking by the Copper Development Association Inc. and PROCOBRE-Chile, with funding provided in part through the International Copper Association, Ltd. The new database will permit Spanish-speaking technologists to access publications maintained by PROCOBRE-Chile by means of standard keyword searches. In addition, a new Spanish- English thesaurus has been written to enable Spanish-speaking individuals to search d access the Technology and Environmental databases of the Copper Data Center, which together comprise more than 80,000 publications dealing with the production, properties, uses and environmental effects of copper. Planned expansion of the new Spanish literature database is described.

Jan 1, 1999

By S. Y. Tan

As continual complementary metal?oxide?semiconductor (CMOS) scaling requirements, metal gate/high-k dielectric/Si gate stacks are expected to replace poly-Si/SiO2/Si gate stacks in the future CMOS sub-45 nm technology node. Hafnium based oxide is a promising candidate to replace SiO2 as a gate dielectric, due to its much higher dielectric constant (high-k) and stability. The key challenges of successfully adopting the high-k dielectric/Si gate stack into advanced CMOS technology mostly come from the interfacial properties. The origins of the electrical and physical characteristics of the dielectric oxide/bulk interface were studied in detail. The leakage current density-voltage (J-V) and capacitance-voltage (C-V) measurement techniques were employed to study the dielectric oxide/Si interface. The effects of the post-deposition annealing (PDA) treatment on the interface charges of dielectric oxides were studied. We found that the PDA can effectively reduce the trapping density and leakage current, and eliminate hysteresis in the C?V curves. Besides, the changes in chemical bonding features at HfO2/Si, HfSiO/Si and HfSiON/Si interfaces due to PDA treatment were evaluated by XPS measurements. The XPS analysis provides a better interpretation of the electrical outcomes. As a result, both HfSiO and HfSiON films have exhibited superior performance in terms of thermal stability and electrical characteristics.

Jan 1, 2010

By Pengfu Tan

A thermodynamic model has been developed to model the desilverising process of lead by the addition of zinc during lead refining, whereby silver-zinc solid solutions are formed, and floats out of the dissolved zinc/silver in the lead bath. The solubility of silver-zinc solid solutions in lead decreases with falling temperature. A number of variations and modifications of the desilverising process are modeled, and applied to a wide range of silver contents in lead bullions in the industry.

Jan 1, 2005

By Valentine A. Chanturiya

The aim of this paper is basically to show progress in the study of nanosecond processes involved in the disintegration and breaking-up of mineral complexes with fine noble metals. We studied the influence of nanosecond High-Power Electromagnetic Pulses (HPEMP) on the physical and technological properties of refractory gold-containing ores and beneficiation products. Experimental data are presented to confirm the formation of breakdown channels and selective disintegration of mineral complexes as a result of pulse irradiation, which makes for efficient access of lixiviant solutions to precious metal grains and enhanced precious metal recovery into lixivia during leaching. Preliminary processing of gravity concentrate with a HPEMP resulted in significant increase of gold and silver extraction into lixivia during the cyanidation stage, with gold recovery increased by ~31% (from 51.2% in a blank test to 82.3% after irradiation). Gold recovery from stale gold-containing dressing tailings products increased after pulses-irradiation from 8-12% to 80-90%.

Jan 1, 2006

By Qing Bo

In this study, the cobalt oxide precursor was prepared in open-style reactor in the condition of high reactant concentration, and then the precursor was decomposed to obtain the cobalt oxides (Co3O4). The effects of some factors on the cobalt precipitation, the particle size and size distribution, and the micro-morphology were addressed. The factors studied include cobalt concentration, initial pH of solution, temperature and time for the reaction, the charge amount of urea, and the temperature for decomposition. It is determined that the precursor particle is in the chemical composition of Co2(OH)3Cl with fine crystalline. By calcinations under proper conditions, the mono-dispersed cobalt oxide particles were prepared with fine crystalline, about 2 µ m in particle size and regular shape in morphology.

Jan 1, 2006

By Tianjiao Luo

Some literatures discussed on how to recycle the various reagent, but the discussion on how to reuse the waste liquid directly is very little. How to reuse the waste liquid directly was researched in this paper. Firstly, the waste liquid should be filtrated to remove the impurity; then some quantity of H2O2 solution was dripped into the waste liquid to pretreat it; finally, CuSO4solution was added into the treated waste liquid and the pH was adjusted to about 12, then some HCHO solution was added into the waste liquid, in which the treated carbon fiber can be plated. The morphology and composition of coatings were investigated by means of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), the deposition rate was mensurated by the way of dissolution. The results indicated that, the plating effect was basically identical with new plating solution, and the solution is stable, and the plating rate is still about 0.8µm/h, and the copper coating is even and combines closely with carbon fiber. According to this way, the waste liquid can be reuse 5~7 times.

Jan 1, 2006

Gas-liquid contacting in the packed bed is a common operation in metallurgical reactors. Research has shown that, unlike wetting flow, non-wetting liquid flows in the form of discrete droplets or rivulets. Thus, modeling of the liquid phase as a continuum is in contradiction to the observations. Also, for the non-wetting case, continuum models have failed to describe liquid flow path when the liquid source is a point source. The aim of the current work is to put forward a combined Lagrangian-Eulerian approach to model the liquid and gas flow in the packed bed. Liquid is assumed discrete and modeled using a force balance approach. Gas is assumed to be interpenetrating continua and modeled using k-emodel for turbulent flow. Structured packing is assumed and x- ray imaging technique is used to visualize liquid flow lines in the bed. Simulation results for liquid flow path compared with the experiments.

Jan 1, 2006