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By Y. Mori, K. Kawanaka

The permeability changes during the sintering of the feed for the Imperial Smelting Process (ISP) were investigated using an experimental sintering pot, as well as with a mathematical model. The results obtained were as follows. The blowing resistance in the sintering bed changes as the sintering reaction proceeds. It increases at the beginning of the reaction when the temperature of the bed is still low. Then it decreases as the reaction continues, accompanied by an increase of the bed temperature. The increase of the blowing resistance in the bed during the sintering process mainly occurred in the drying zone, and was comparatively small in the reaction and cooling zones. Based on Erugen's equation, the change of the permeability during sintering is explained by the decrease of the apparent fractional void volume in the drying zone of the bed.

Jan 1, 2000

By K. Watling

Vibrational spectra of surface and solution compounds formed during cyclic voltammetry of a gold electrode in a deoxygenated 0.01 mol dm-3 NaCN solution have been examined using surface-enhanced Raman scattering (SERS) spectroscopy. The presence of cyanide at the electrode surface was indicated by Raman bands characteristic of the carbon-nitrogen stretch, CN.. Chemisorption of cyanide on the gold surface was evidenced by the presence of vibrational modes due to gold-carbon stretching, AuC, and gold-carbon-nitrogen bending, AuCN. Prior to the disappearance of the surface cyanide stretch band, a limiting value of the CN was obtained, the same as the value reported for adsorbed cyanide. Effects upon the voltammetry and vibrational modes of surface species due to additions of silver and lead to the gold-cyanide system have been observed.

Jan 1, 2003

By Marcelo E. Andia

In Chile, a significant amount of mining takes place in varied geographical environments. Mining activity extends from copper and gold deposits located in the Atacama Desert 4.500 meters above sea level to underground coal workings beneath the sea floor. This diversity in location and environment presents many challenges in the development of competitive and environmentally sustainable mining activities. An important future issue will be how to close these mines in an appropriate way once economically exploitable ore reserves have been exhausted. This poses challenges for both the government and companies alike, considering that Chilean law currently lacks legislation specific to mine closure. This paper examines the risks associated with mine closure based on international experience, and identifies those risks specific to Chilean regions. The main regions in Chile where mine closure legislation should be applied are identified.

Jan 1, 1999

By Guray Kaya

Boron minerals are widely employed in various fields such as ceramic, glass, cement, metallurgy, etc. Although boron deposits of the world are limited, the production level of boron-based products is continuously increased. Turkiye possesses approximately 73 % of total world boron resources. Etibor Kirka Borax Company of Turkiye produces tincal concentrates and borax pentahydrates. During such productions considerable amounts of concentration and derivation wastes appear. Having considered the increased rate of production it is quite obvious that the level of relevant wastes will also be raised. With this study it was aimed to utilize these wastes in roof tile and brick bodies and to convert them into a form environmentally and human friendly. Newly produced products were undergone to several standard tests for the determination of their shrinkage, water absorption, strength values and coloring parameters. Additionally, micro structural studies were conducted.

Jan 1, 2006

By Jae-Chun Lee

Di-2-ethylhexyl phosphoric acid (D2EHPA) is widely used for separating rare-earth elements. In commercial plants, rare-earths are usually stripped from loaded extractant streams using mineral acid, then precipitated as oxalates. Many rare-earth uses demand specific powder characteristics, which are obtained by secondary processing. This paper demonstrates the feasibility of combining the stripping, precipitation and powder processing stages, thereby achieving considerable savings. MEHPA solutions were loaded with yttrium, then emulsified with oxalic acid-HC1 solutions to precipitate yttrium oxalate, which was readily calcined to yttrium oxide. The precipitation kinetics and yield were sensitive to process conditions. The morphology and size of the yttrium oxalate powders varied with the concentrations of D2EHPA and oxalic acid, and the presence of SPAN 60, which affected nucleation, growth, and the emulsion characteristics.

Jan 1, 1992

By Antonio Martin, Jesus Hurtado, Francisco Jimenez

"Atlantic Copper is one of the largest copper producers in Europe. Its production facilities, including a primary copper smelter and an electrolytic refinery, are located in Huelva, on the southwest coast of Spain. These installations enable the smelting of over 1 million tpy concentrates to produce up to 260,000 tons per year of cathodes and 900 ktpy of sulphuric acid.Since 1970, several improvements have been made at the Converters Area such as modifications of primary hoods, operations with an OPC system, installation of scrap chargers, the recent installation of the secondary hoods and other environmental projects. All these modifications have been aimed at increasing the capacity of our smelter while keeping our continuous environmental commitment.This paper describes the modifications and improvements carried out at the converters area and our proposals for future developments."

Jan 1, 2012

By Bruno Augusto Batista Ribeiro, Felipe Terra Elias, Wagner Moulin Silva

In the pyrometallurgical production of copper from its sulfides, converting in the Peirce Smith (P-S) Converter is still the most widespread method to obtain white metal and blister copper from the matte. Despite the fact of being a century-old process, it is still possible to achieve improvements in the process, by the use of modern tools, one of the most valuable being numerical calculation and computer-aided simulation. The present study presents three cases in which the angle for the gas injection and the number of working tuyeres are changed during the slag blow phase of the converting process. It was noticed that a decrease of the number of tuyeres, followed by an increase in the injection gas velocity, results in improved reaction volume and less stress to the refractory lining. However, an increase in the amount of copper lost to the slag as oxide is likely to occur.

Jan 1, 2014

By P. R. Taylor

Diamond films have been successfully formed in an inductively coupled plasma (ICP) chemical vapor deposition (CVD) system from several gas mixtures: CH,-H,, C2112-112, and C2112-112-02' Our previous thermodynamic study indicated that the substrate temperature could be lowered by the presence of oxygen species at moderate system pressures (0.3-0.5 atm) and that higher volumetric growth rates required a high temperature source and a moderate pressure system in CVD processing. The principal experimental results were consistent with the thermodynamic predictions. The deposited films were characterized by laser Raman spectroscopy, scanning electron microscopy, and X-ray diffraction. The films were well faceted and uniform, with the growth rates over 10 pm/hr on molybdenum substrates. The crystal size ranged between 1 and 2 microns for a two hour experiment. It was possible to decrease the substrate temperature to below 800 °C in this system.

Jan 1, 1995

By Shanlu Yang

In this study, laser-GTAW hybrid welding was used to the lap joint of galvanized dual-phase (DP) 980 steel in a gap-free configuration. The effects of welding parameters such as the laser power, the distance between the laser beam and the electrode torch, the arc current on the quality of hybrid welds were fully studied. The reason for the formation of different weld defects arises from the development of the highly-pressurized zinc vapor at the interface of two metal sheets. Experimental results demonstrated that the elongated molten pool introduced by the GTAW can suppress the formation of spatters to some extent. However, the hybrid laser-arc welding process still suffers from a large amount of spatters that degrade the weld quality. Furthermore, it was found that the weld quality was enhanced with the increase in the laser beam-arc distance and welding current.

Jan 1, 2009

By C. Alexandru Sonoc

Donnan Dialysis uses ion exchange membranes to extract and separate cations. The driving force is provided by differences in chemical potential, rather than by electric fields or pressure. A Donnan Dialysis based process to recover lithium, nickel, cobalt, manganese, and organic acid lixiviant from recycled lithium ion battery cathodes is under development. In this paper we present a model of Donnan Dialysis and results of simulations of the aforementioned process. The simulations show that 170 m2 of membranes can process 1000 L of leachate ([Li+] = 0.285 M, [Co2+] = [Ni2+] = [Mn2+] = 0.095 M, pH 2) in two days and recover 94.1% of the lithium (as lithium carbonate), 99.4% of the transition metals (as mixed sulphates ready for solvent extraction), and all of the organic acid using 423 mol of H2SO4 and 268 mol of KHCO3.

By Min Chen

A numerical simulation of the stress field of the solidified shell in the mold during continuous casting of peritectic steel slab was calculated with commercial software. The results showed that the maximal stress on wide face of the solidified shell was located at the corner and near middle of the slab, and it increased with increasing the width of slab. In addition, the stress was also influenced by operating parameters such as superheat degree, drawing speed and cooling intensity of the mold, and the maximal stress value and its position changed with these parameters. For the slab with section size of 3200mm×150mm, the proper drawing speed was around 1.2m/min, with cooling intensity of 5500L/min while the superheat degree was 15°C to 25°C in order to prevent longitudinal crack occurring during peritectic steel continuous casting.

Jan 1, 2009

By Jack A. Simon

My remarks are directed at relating some of the mineralogical approaches mentioned in the preceding presentations to emerging energy issues. The assembling of this symposium on process mineralogy attests to the growing concern for energy development from the non-petroleum mineral fuels and the unconventional petroleum fuels. A report in 1979, prepared under the auspices of the National Research Council/National Academy, of Sciences, was published in two parts and dealt with "Redistribution of Accessory Elements in Mining and Mineral Processing." This report rather comprehensively considers broad aspects of minerals associated with the solid fuels considered in this symposium and focuses attention on some problems of process mineralogy relative to these fuels. Papers have dealt with coal, oil shale, tar sands, and uranium minerals. Problems associated with mining, processing, and use of these materials have significant differences, but also have some factors in common relative to the subject of this symposium.

Jan 1, 1981

By Guillermo J. Román

The precipitation of copper and zinc as cements from a copper alloys' spent pickling solution has been studied at laboratory and pilot scale, with the objective of designing an economic process to recover both metals and render a solution to be either recycled to the pickling process or treated in a standard fashion and produce a non-hazardous sludge. The sulfuric acid spent pickling solution already containing copper and zinc was used first to dissolve another solid residue originated in the copper alloys foundry to neutralize part of the acidity. The resulting enriched solution was treated separately with two reductants,; sodium borohydride and iron powder varying pH and excess of reductant under constant agitation. Under the best conditions, precipitation of over 95 percent of zinc and copper was achieved together with the reduction of lead and cadmium contents respectively. A process for the combined residues treatment is proposed.

Jan 1, 1995

By F. Tailoka

In order to decrease the voltage required for electrorefining, a recessed electrode cell has been developed in which the anode and cathode have recesses machined into their faces. The anode and cathode plates are separated by a thin refractory cloth and the cell is filled with fused salt. Bismuth containing 10 to 90 % lead with copper and silver as minor impurities has been electrorefmed at a current density of 10,000 to 20,000 Am-2. The cell voltage was between 285 and 635 millivolts and the bismuth was refined to a purity of 99.9 %. Flow patterns were observed in a room temperature model of the recessed channel cell using water and mercury to simulate molten metal and the fused salt electrolyte. The flow in the electrode recesses is characterized by discrete droplets when the liquid flow rate is low and thin streams and rivulets at higher flow rates.

Jan 1, 1995

By W. H. Jay

Sulphide-containing minerals, particularly iron, lead to acid formation. In turn, the acid generates effluents such as copper acid drainage (AMD). The Berkeley Pit in Butte, Montana, USA and Mt Lyell in Tasmania, Australia, represent just two of many sites throughout the world for which acceptable treatment methods are required. In the gold cyanidation process, the presence of copper creates both a significant cost impediment and a potential environmental hazard. The tailings dam failure at Baia Mare in Romania which led to the release of copper and zinc cyanides created a major environmental disaster. The application of non-toxic water soluble polymers and ion exchange resins to selectively recover copper from AMD solutions, and the in-plant treatment of copper cyanide solutions and slurries to recover copper and recycle cyanide to prevent cyanide entering the tailings impoundment will be discussed. The economics of the various processes will be highlighted.

Jan 1, 2003

By Corby G. Anderson

Over the past 15 years, numerous pressure oxidation plants for pretreatment of gold ores and concentrates have been installed throughout the world. While this technology is now established, it suffers in terms of the complex engineering and operational characteristics inherent in utilization of high temperatures (i.e. up to 225oC) and high pressures (i.e. > 3000 kPag). This paper outlines the application of an industrially proven pressure leaching methodology utilizing nitrogen species catalyzed pressure leaching and alkaline sulfide gold leaching. As such, it stands as an economic and engineering advancement in pressure leaching and non-cyanide treatment of gold ores and concentrates. In particular, the technology offers significant technical and economic advantages over traditional pressure oxidation and cyanide gold recovery in the treatment of gold bearing chalcopyrite ores and concentrates. An example of this will application will be delineated in this paper.

Jan 1, 2003

By R. K. Amankwah

The ability of Streptomyces viridosporus in sorbing heavy metals from wastewater has been investigated. It was found out that the biomass of the soil microorganism could be used in sorbing Pb2+, Cu2+, Zn2+ and Ni2+ ions from acidic solutions of metal ion concentration between 10 and 100 ppm. Over 99% of Pb2+ and 88% of Cu2+ ions were sorbed from wastewater of concentration 10 ppm with Ni2+ and Zn2+ recording values below 50% for a contact period of 4 hours. The quantity of metal ions sorbed per gram of biomass from the wastewater was in the order Pb2+ > Cu2+ > Ni2+ > Zn2+ and this is related to their electronegativities. Biosorption was sensitive to variations in pH and in the range investigated; metal binding was optimum at 5.5. About 63% antimony was also sorbed from dilute cyanide solution.

Jan 1, 2003

By Mineo Hayashi

Gresik plant, PT Smelting, is the first and the only copper smelter and refinery in Indonesia. It had the original design capacity of 200,000 tpy of LME grade A cathode production and treats copper concentrates mainly coming from Grasberg mine in Papua, Indonesia. The smelter that employs the Mitsubishi process was put into operation at the end of 1998. In April 2004 the refining capacity was expanded up to 259,000 tpy in order to meet with soaring demand of copper cathode in South East Asian market. In addition, the construction work for the second refinery expansion project has started and it is scheduled to be completed in July 2006. At the completion of the project an additional 12,000 tpy capacity will be assured and in total it will make 271,000 tpy,. This paper describes the chronology of the expansion and future operational strategy of Gresik plant.

Jan 1, 2006

By Jun-ichiro Yagi

A mathematical model has been developed for simulating the blast furnace operation with carbon composite agglomerates charging based on multi-fluid theory and reaction kinetics. In this model, the behaviours of carbon composite agglomerates are considered on the basis of previously reported conservation equations and experimental research on the reduction rate of carbon composite agglomerates. A series of calculations are performed to examine the effect of charging carbon composite agglomerates. The model calculation gives two-dimensional distributions of process variables and information on the overall operational parameters. It reveals that in-furnace temperature levels significantly decrease and the reduction of carbon composite agglomerates is retarded with carbon composite agglomerates charging ratio. The furnace performance is remarkably improved with the increase in carbon composite agglomerates rate. The productivity tends to increase while coke rate and total reducing agent rate show decreases at the different degree.

Jan 1, 2006

By Frédéric Pineau, Guillaume D'Amours

Semisolid metal processing of metallic alloys takes advantage of the thixotropic behavior of material with non-dendritic microstructure to produce near-net-shape components with improved mechanical properties. The much higher apparent viscosity of the semisolid billet limits the risk of oxide formed on the free surfaces to become incorporated into the easting during the process. But, the external-skin on the periphery of the billet, which is often partially solidified and contaminated with lubricants, should not be included into the casting as this can be a cause of reject for most structural parts. In this paper, a preliminary model is set-up using the LS-DYNA SPH formulation to follow the paths of the skin. Calculations carried out show that this approach appears to be very promising to predict the paths of contaminated skins into semisolid castings. It can then be utilized to design suitable molds and gating systems.

Jan 1, 2012