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By L. A. Barta

A new process for the leaching of chalcopyrite concentrates has been developed and tested in miniplant campaigns and locked cycle testwork carried out between 1996 and 1999. The process involves pressure leaching in a sulphuric acid solution, e.g. raffinate from copper solvent extraction. Iron in the feeds is precipitated predominantly as hematite in the autoclave, simultaneously with copper extraction. Gold and silver in the pressure leach residue are recoverable by conventional cyanidation, following flotation to remove elemental sulphur by-product. The results of recent miniplant tests and batch locked cycle tests are provided.

Jan 1, 1999

By Barry T. Kilbourn

There is a continuous quest for better-performing materials, for example, to withstand higher temperatures, to resist more efficiently degradation or to be electrically conductive under extreme conditions. The oxides, and similar compounds, of the lanthanides and yttrium can, in some cases, help provide such behavior. Other advanced materials, such as hydrocarbon catalysts, optical ceramics or sensitive phosphors, may also require these oxides for some essential function. The role of the oxides in a wide variety of technologies, some novel and developing, will be reviewed and the underlying physico-chemical principles, the common threads, between several less well-known and apparently unrelated uses discussed.

Jan 1, 1989

By W. Persson

The first installation at a copper smelter of a Semtech OPC System for continuous, on-line production control of copper converting in PS converters took place in 1994. At present OPC systems are installed at 19 PS converters. The technology presents to the operator real-time information on the progress of the process he is controlling in the form of optical process parameters, thus facilitating dynamic process control. The optical process parameters are based on time- and wavelength resolved registrations of the light emitted by the off-gas flames and identification of correlation between these parameters and characteristic metallurgical process data. The present paper provides a description of the technology as seen by the furnace operators and a summary of operating experiences made during five years of full-scale, operation at various smelters, reviews influences from the technology on smelter operational practises and comments on recent developments as regards new applications of the technology.

Jan 1, 1999

By Ioannis Paspaliaris, Dimitrios I. Gerogiorgis, Dimitrios Panias

"Red mud fiberization is a process with remarkable potential, alleviating environmental pressure by transforming an aluminum by-product into mineral wool, thus to various marketable products. A promising mineral wool process is molten slag fiberization via an impinging air jet, which avoids mechanical wear and rotating parts. The molten slag which remains after pig iron casting flows out of a heated ladle orifice at a high temperature (1600 °C) and adjustable flowrate, and forms a free-falling vertical jet which visibly radiates its excessive heat: at a given distance, a high-velocity impinging air jet meets the vertical melt jet perpendicularly (or at an angle), inducing intensive droplet generation, subsequent fiber elongation, collection and processing.This paper focuses on high-fidelity CFD modeling of the molten jet flow under external cooling: the model encompasses all physicochemical phenomena (melt laminar flow, radiative cooling) and considers several temperature-dependent slag transport properties in order to understand which operational degrees of freedom (manipulated variables) are useful to process optimization."

Jan 1, 2012

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 Roberto Parada

In a long term program for the optimization of the Outokumpu Flash Smelting Furnace at Chagres Smelter many different subprograms are being developed. One of them is the design and application of a sampling method that can allow the direct diagnostic of the quality of the copper concentrates combustion. We present in this paper the evolution of the sampling devices used in a ten months of continuous sampling campaigns and an example for the sulfur elimination and magnetite formation in the flame from 60 cm to 100 cm under the burner. These type of information combined with the appropriate mathematical modeling of the combustion must propose some considerations to correct the classic criteria in the preparation of the charge for the smelting of copper concentrates based only on the mass and energy balance from the chemical and mineralogy composition of the concentrates.

Jan 1, 2006

By Chai Li-yuan

The anodic behavior of AZ31 magnesium alloy in NaOH alkaline solution was investigated in this paper. The effects of anodizing parameters, such as applied current density, concentration of NaOH and temperature of the solution on the formation, structure and surface morphology of the anodic films were also studied. The formation of the anodic film was analyzed by analyzing the anodic polarization curves, the potential-time curves and XRD, SEM graphs of samples obtained at different anodizing time. The results of corrosion resistance tests, XRD and SEM observation showed that the temperature greatly affected the formation and anti-corrosion property of the anodic film, but the concentration of NaOH not. The film with best anti-corrosion resistance was obtained at applied current density of 10mA/cm2, 353k in 1mol/l NaOH solution.

Jan 1, 2006

By M. Arenas

A corrosion study of a bonded NdFeB permanent magnet materials alloyed with titanium carbide additions has been undertaken. The materials were produced by rapid solidification by melt spinning. Commercial epoxy was used as a bonding medium. The corrosion results were compared with those of a near stoichometric unalloyed NdFeB. Anodic polarization and potentiostatic techniques in 0.9 M Na2SO4 solutions were used to characterize corrosion behavior. It was found that the addition of 6 a10 Tic resulted in superior corrosion resistance, as indicated by lower corrosion currents and less iron dissolution at fixed potential.

Jan 1, 1997

By Toshiyuki Kozuka

CdTe semi-conducting materials have been expected as solar cell materials because its theoretical energy conversion ratio is very high. The actual efficiency still low, however, many research works have been done in order to improve the efficiency. And crystal orientation is one of possibilities for that. In this work, a new method using intense magnetic field for a control of texture of CdTe crystals will be proposed, where the CdTe film was electro-deposited under an intense magnetic field. CdTe is less affected by magnetic field, because of its cubic structure, but Cd or Te has hexagonal structure, which is sensitive for magnetic field. In this paper, crystal orientation of Cd or Te film, which can be utilized as basic layer for CdTe deposition, will be developed.

Jan 1, 2006

By Kwang-suk You

This paper describes the characteristics of electric arc furnace slag (EAF slag) as an aggregate of concrete along with the chemical composition, leaching concentration of heavy metals, the soundness of EAF slag and compressive strength of mortar with 20% and 50% replacements of sand. The results showed that leaching of heavy metals and soundness of EAF slag satisfied Korean environmental limit and Korean Industrial Standard for aggregates. The compressive strength of mortar increased as the replacement ratio of EAF slag for sand increased.

Jan 1, 2006

By T. W. Gonzales

The BHP San Manuel Smelter operates an Outokumpu Oy flash furnace, conventional Peirce-Smith converters, anode casting facilities, and two double contact sulfuric acid plants. The flash furnace was commissioned in July 1988 and since then, the smelting capacity has been continuously increased to 30% above design. The converter operation was challenged to process larger amounts of matte with existing capacity. Utilization of industrial technological improvements and people technology transformed the Converter Department from a constraint to easily accommodate the new demonstrated flash furnace capacity. This technology also increased secondary consumption, converter campaign life, and reduced operating costs. This paper will describe the important Converter Department achievements in the past five years.

Jan 1, 1999

By R. Y. Wan

Thiocyanate was evaluated for gold recovery from low-grade refractory gold ores following biooxidation for an acidic heap leaching approach. One of the important features in using thiocyanate is that the leaching can be performed in acidic media, thus avoiding problems related to neutralization and material handling as leaching with alkaline cyanide. Also, the acidic leaching enables the use of ferric ion or bioleach solution as oxidants. In this study, Newmont-Nevada low-grade refractory sulfidic ore was biooxidized in columns at a particle size of 100% passing 102 mm. Thiocyanate leach on the biooxidized ore sample was performed on both ground samples in pulps and coarse material in columns using ferric ion as an oxidant. The variables of thiocyanate and ferric ion concentrations were compared for effect on leaching. Thiocyanate leach results are encouraging and indicate potential for development of a practical process. Gold extractions by thiocyanate are comparable to cyanide leach. Thiocyanate consumption was higher than cyanide, but was in an acceptable level.

Jan 1, 2003

By Maria Cristina Ruiz

The removal of iron from the leaching circuits is a common problem in the hydrometallurgical processing of non ferrous metals. Among the currently available processes, hematite precipitation is the most recommendable from an environmental point of view. This paper is concerned with the batch precipitation of hematite from ferrous sulfate solutions. One of the main objectives of the study was to determine the effect of the experimental conditions on the extent of iron precipitation as well as the purity and the particle size distribution of the precipitates. The main variables studied were temperature (180 to 220 ºC), concentration of sulfuric acid (1 to 10 gpl), initial iron concentration (1 to 15 gpl) and partial pressure of oxygen (3 to 7 atm). The results showed that increasing the oxygen partial pressure from 3 to 7 atm produced a very small increase on the rate of hematite precipitation indicating that a large partial pressure of oxygen is not needed for an effective ferrous to ferric oxidation. An increase in the temperature produced finer precipitates with lower sulfur contents. On the other hand, an increase in sulfuric acid concentration and initial iron concentration produced precipitates with larger particle sizes and higher sulfur contents.

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 Peng Bing

Stainless steelmaking dust is classified as a hazardous waste due to higher than acceptable heavy metal leachabilities such as zinc, lead, cadmium and chromium. In addition to being an environmental hazard, the flue dust is also an economical concern to stainless steelmakers as it contains large amounts of valuable alloying elements, especially for iron, chromium and nickel. A new technology of direct recycling of stainless steelmaking dust has been developed to recover the metals from the dust. But it was found that zinc was accumulated in the dust collection system in practical run of direct recycling. This study focuses on the effect of the operating parameters such as temperature, dust feed rate and the ratio of CO to dust on the reduction of zinc oxides present in the dust. The mathematical model for the reduction process was setup based on the experimental research. According to the mathematical model, the temperature has obvious effect on the reduction of zinc. It is benefit to the process of zinc reduction to increase the temperature. But the temperature will not be the main factor for the reduction process after 1228C. It will promote zinc reduction to decrease the dust feed rate and control the ratio of dust to CO. It was also found from the experiments that ZnFe2O4 in the dust could be decomposed at high temperature. Decomposing ZnFe2O4 in the dust increases the recovery of zinc from the dust distinctly.

Jan 1, 2006

By Alex Moyano

The Peirce-Smith converters are traditionally carrying out the converting process of a copper matte in the smelters of Codelco-Chile. However, its production increment is very limited due to the investment magnitude associated to the fulfillment of the environmental regulation. The objective of this paper is to present the Codelco continuous converting process technological advance when converting mattes and/or white metal into blister copper in a Teniente converter unit as an alternative to increment the corporative anode copper production. In 1994, Codelco-Chile started evaluating its ?home made technology? as an alternative to the traditional batch-type converting process. By the year 2001, the Caletones smelter converted liquid white metal to blister copper in a rearranged PS converter continuously. Then, during the 2001-2003 period, several pilot and industrial scale tests were done in a Teniente converter unit at Codelco Norte smelter, evaluating the continuous converting process, i.e., processing liquid mattes (62-68% Cu) to blister copper, demonstrating its technical feasibility with: (i) both constant production of gas flow and SO2 concentration, (ii) production of liquid slag, and (iii) production of a clean blister copper, suitable for the refining process. The promising results have led Codelco-Chile to plan for the 2006 period, a next advanced stage for the continuous converting process evaluation by carrying out a new campaign of tests in a Teniente converter unit at the Codelco Norte smelter.

Jan 1, 2006

By Li Rongxing

A general regular solution model put forward in this paper defines a general interaction parameter that includes both composition and temperature dependence. On the basis of this model, analytic express of solution excess properties was obtained by least square fit using the composition and temperature relations in binary alloy phase diagram. After some solution excess properties analytic expresses of correlated binary alloy system obtained, the analytic express of ternary alloy system could be obtained by superposition of general geometrical model. The ternary alloy system Pb-Sn-Zn has been predicted in terms of this method and the result was very in agreement with actual measured value.

Jan 1, 2006

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 Zviad Kovziridze

It is stated that the specific character of SPHTS specimens of TiCx consists in crystal lattice strength reflecting the condition of synthesis in ?burning wave?. The use of roentgenographic and other methods of analysis allow to estimate the effect of the conditions of synthesis causing the carbon sablattice defect on the grinding intensity of TiCx -phases. The study of the kinetics of vibratory grinding of TiCx -phases in ethanol and benzene medium allows to establish high grinding intensity of the phases close to stoichiometry and the possibility of producing high dispersion powders (Ssp 4.5-6 m2/g).

Jan 1, 2006

By Gustavo A. Munoz

Activated carbons owe their adsorption capacities to their extensively developed pore network structure. As a result, these adsorbents generally exhibit high specific surface areas. Currently, granular activated carbons produced from coconut shells are traditionally used for gold recovery by adsorption from cyanide leaching solutions. Magnetic activated carbons (MACs) for gold recovery from cyanide solutions produced from sources other than coconut shells have been developed at the University of Utah by mixing a magnetic precursor with a carbon source, and treating the mixture under controlled conditions of temperature and gas phase composition. The pore size distribution of the activated carbons is dependent on the degree of activation, among other factors. The significance of the MAC pore size distribution on gold adsorption kinetics and gold adsorption capacity is presented.

Jan 1, 2003