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By Gerardo R. Alvear

The ability to efficiently remove impurities contained in concentrates is a key point to consider when selecting copper smelting technology for new plants or modernisation projects. Volatilisation of impurities such As and Sb should occur as early as possible in the process, and preferably in the smelting furnace, so that they do not impact on downstream unit operations. The ISASMELTTM process has been demonstrated to remove impurities efficiently, through high levels of volatilisation. This behaviour is promoted by attributes of the process such as the strong bath agitation, and the flexible nature of the process design, allowing the operator to choose the optimal matte grade for impurity partitioning, and the positive effect of the moisture content in the feed. This paper presents the distribution of minor elements in the copper ISASMELTTM furnace. Distribution impurities of As, Sb, Pb, Zn and Co observed in the ISASMELTTM furnace at Mount Isa Smelter are reported. Then, based on plant results and thermodynamic considerations, the potential application of ISASMELTTM technology for processing complex concentrates is discussed.

Jan 1, 2006

By Morimasa Ichida

One of the key factors of stabilized blast furnace operation under the conditions of high productivity and high pulverized coal rate is to enlarge the raceway to reduce the dead man area. With a reduced dead man area, the descent area is enlarged and the central gas flow is maintained at the same time. In this study, raceway furnace experiments were conducted with tuyere velocity and coke strength changed both in hot and cold conditions to measure the coke degradation rate. Using the coke degradation rate measurements, we examined the equivalent relation between the coke strength and tuyere velocity for coke degradation in the raceway. In addition, in this paper, we discuss the increase in tuyere velocity in relation to an increase in coke strength.

Jan 1, 2006

By Pierre-François Bareel

EU legislation imposes ambitious recycling targets for various consumer goods. End-of-Life Vehicles (ELVs), scrap iron and various proportions of Waste Electrical and Electronic Equipment (WEEE) are processed by shredding plants which recover most of the metals but produce Shredder Residues (SR) which are landfilled. They represent 20 to 25 wt.% of the shredder input. Energy issues for the coarse fraction of SR are now largely studied. However, below 2 mm, the calorific value falls off drastically. These Fine Shredder Residues (FSR) represent up to 55 wt.% of the total SR. To meet European objectives other alternatives to landfilling must be considered for the FSR. The present paper describes a study carried out to characterise the FSR and investigates ways to process them and produce marketable products. Applying Gy's theory, a sampling procedure was conducted over two years to statistically quantify the variability of the physical and chemical properties of FSR produced by a Belgian post-shredding treatment plant. Macroscopic characterisation has led to the identification of four material categories which could be separated according to their physical properties: ferrous metals (more or less oxidised), non-ferrous metals, an organic fraction (plastics, rubber, textiles, foams, wood) and a minerals fraction (glass, ceramic, concrete). The entrainment of small metallic particles within the pores of organic fragments will affect the quality of the separations.

Jan 1, 2006

By Antrekowitsch Jürgen

The recycling of residues from metal producing by-products has become a main field of interest in metallurgical investigations. Forced by a stricter environmental legislation and the resulting increase of landfilling costs, combined with the aim to recover as many valuable metals as possible, a lot of different processes have been developed in the last two decades. Because of the high yearly tonnage residues from the iron and steel industry like slags, dusts and sludges have moved in the center of interest. Dusts from the steel mill, containing heavy metal oxides and halides did not play a considerable role as secondary raw materials for a long time. They even contain a huge amount of leachable elements and compounds which cause noticeable problems in case of a dumping. Nevertheless, the implementation of a new landfilling regulation, including a prohibition of aboveground dumping without inertisation, caused a rising interest concerning recycling technologies for such residues. In addition, the zinc content of these dusts became higher and higher and began to play the most important role for the economy of dust recycling.

Jan 1, 2006

By Fatma Arslan

Alada (Kayseri-Turkey) lead-zinc sulfide-oxide ores contain 10.17% Pb, 10.98 %Zn, 164 g/t Cd and 57 g/t Ag. During the laboratory scale flotation tests of these ores, it was found that almost all zinc was remained in the tailings that contain 12.31% Zn, 1.35%Pb, 198.3 g/t Cd, and 22.3%Fe. Three different methods were studied such as basic (NaOH) leaching, roasting+acidic (H2SO4) leaching and direct acidic (H2SO4) leaching for recovering metals that these tailings contain. In the direct acidic leaching, which gave the best results, dissolution efficiencies of 91.5% zinc, 78.2% cadmium, and 14.3% iron were reached at the optimum leaching conditions while Pb remained in the leach residues and the acid consumption was 422.3 kg/ton of tailings.

Jan 1, 2006

By Shunsuke Yagi

A surface alloying technique was investigated using alternating pulsed electrolysis in an aqueous solution containing a single metal component for the formation of an Fe-Cr layer on an iron substrate. In the process, the iron substrate was dissolved during each anodic polarization of the pulsed electrolysis, providing iron ions in the vicinity of the substrate, while the Fe-Cr alloy was electrodeposited during subsequent cathodic polarizations. A bright, flat, and crack-free Fe-Cr layer with a composition gradient was obtained using a solution containing a trivalent chromium component and a complex forming agent together with some supporting or buffering salts.

Jan 1, 2006

By Nexhmedin Lohja

Macro management of metallurgical industries becomes an important issue in certain situations especially when some government owned metallurgical industries are on the verge or have stopped being feasible. In these cases a government lead macro management in collaboration with domestic institutions and foreign scientific and management expert companies is decisive in order to steer them to a profitable path. This process is not necessary an easy one and incorporates many unknowns and various alternatives. In this paper the macromanagement of the metallurgical industries in Albania will be described as a particular case along with a survey of its mineral deposits, metallurgical facilities and various perspectives for future development. As a country with many mineral resources, the exploration, research, exploitation and processing work of mineral ores before 1990 constituted an important activity of its economy, especially in the exportation of various products of this industry. Since 1990 this activity slowed downs considerably for various reasons and this prompted the necessity of a government lead macromanagement in collaboration with domestic institution and foreign expert companies. This process aims at improving and renewing the technologies in the metallurgical industry in order to transform it into a feasible branch of economy. This goal is being implemented among others through proper geological surveys, rehabilitating and renewing the existing facilities through domestic and foreign investments, the transformation of the ownership or the management from state-owned to local or foreign private companies, etc. Priority is given to the raising of the processing range of the traditional minerals such as chromium, copper, nickel-iron etc. as well as developing new perspective technologies to treat new mineral deposits.

Jan 1, 2006

By Larry Southwick

In the early 1940's, the Caron ammonia ? ammonia carbonate leach process was used to produce nickel from Mayari ores at the Nicaro plant in Oriente Province, Cuba. While plant operation was generally successful, it was not broadly economical and was shut down. The plant was later restarted in the 1950's and a number of investigations initiated to resolve the more serious operational and performance issues. Processing steps studied included iron reduction (chemistry ? nickel and iron, reductant, equipment), ore variability (homogeneity and consistency of mineral concentrations, serpentine vs. laterite), leach solution strength, nickel recovery (temperature ? reduction and leaching, reoxidation) and a variety of other topics. These studies and their findings will be discussed. Caron himself obtained good results on these ores in the laboratory. They could not be duplicated in the field, the reasons for which will be reviewed. (Note: the ore looked like garden dirt; charcoal made from palm trees was one of the reductants attempted; and ammonia was the leach solution. Mixing the three, so to speak, was to yield nickel.)

Jan 1, 2006

By Zhihong Liu

Monodisperse micron size nickel oxalate particles with rhombohedron morphology were prepared from condensed Ni(OH)2 suspension by a novel gel-sol process proposed by one of the authors. Firstly, condensed nickel hydroxide gel was formed by fast adding 1 mol dm-3 NaOH solution into 0.2 mol dm-3 nickel chloride solution, and then oxalic acid solution with a concentration of 0.25 mol dm-3 was dropped into the gel drop wise through a pump equiped with a pH controller under preset pH value, and in this process, Ni(OH)2 gel was converted gradually into monodisperse nickel oxalate sol. The formation of the nickel oxalate particles was found to proceed through a dissolution-recrystallization mechanism from the nickel hydroxide gel. The product particles exhibited rhombohedron like shape with micron size long axis and sub-micron size short axis. The effects of such factors, as temperature, surfactants, et al, were evaluated experimentally on the particles sizes and morphologies.

Jan 1, 2006

By P. A. Olubambi1

Representative samples of the hydrothermal vein deposits of the bulk complex sulphide ore deposit, 10 km south of Ishiagu, in Ebonyin State, South Eastern part of Nigeria were collected from two small scale mining companies. The samples were mixed and successively crushed in a jaw crusher and cone crusher, and ground in a rod mill. Characterization was carried out with SEM, EDX, XRD, XRF and ICP-OES. Mineralogical analysis revealed the presence of sphalerite, galena, siderite, pyrite, quartz and chalcopyrite. X-ray Diffractometry showed that sphalerite mineral in the ore occurs as sphalerite ferrous with varied percentage of Zn and Fe within the various sizes while chalcopyrite occurs as a chalcopyrite group mineral with chemical formula Cu2MnSnS4. Results of the elemental analysis showed variations in elemental composition within the different sizes.

Jan 1, 2006

By S. Suda

Hydrogen storage materials have been investigated for more than 30 years, particularly on metal hydrides. These materials are, however, considered today impractical because of their poor hydrogen capacity measured by mass density and their poor surface properties and characteristics against impurities. Recent R&D activities have been located in new categories of materials such as complex hydrides and chemical hydrides. Among these materials, NaAlH4 (one of alanates), Li-based complex hydride, and NaBH4 (SBH: sodium borohydride) are 3 major candidates as hydrogen storage materials. In the presentation, SBH as a non-reversible on-site but recyclable off-site is described in view of its practical availability as the source of H- (protide) applied for a new type of fuel cell named Direct Borohydride Fuel Cell (DBFC) and H2 (hydrogen) for Proton Exchange Membrane Fuel Cell (PEMFC).

Jan 1, 2006

By L. N. Ertzeva

The present work is dedicated to investigation of the sulfidizing process of ore pyrrhotite concentrate with recovery of a sulfide material, enriched with non-ferrous metals, and waste pyrite, with downstream separation by a certain beneficiation method.

Jan 1, 2006

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Fernanda Margarido

Recovery of metals contained in the electrode materials of batteries was studied considering an integrated recycling process constituted by physical and chemical operations. The physical treatment included the shredding of the spent batteries, followed by a wet sieving operation of the fragmented material. The physical behavior of Ni-Cd and Zn-Mn based (alkaline and saline) system batteries was studied and compared. In that sense, shredding operation was performed and the sieving of shredded fractions was accomplished to evaluate the efficiency of the separation of electrodes and scrap. For Ni-Cd batteries the loss of electrode material with the supra fraction (scrap) after the shredding operation was lesser than the Zn-Mn batteries. Especially for saline-type batteries, the electrode attached to the scrap was substantial leading to important losses. This difference can be explained by the composition of the case materials and the internal physical constitution of the electrodes. The wet sieving studies carried out allowed optimizing the separation of the electrode fine fractions from the scrap materials through the analysis of selectivity Cd/Fe or Zn/Fe. For Ni-Cd batteries, maximum selectivity was achieved for the granulometry of 1.4 mm, while for alkaline and saline systems best selectivity were obtained at 2.8 mm and 5.6 mm, respectively. This process allowed the recovery of about 70% of electrodes for Ni-Cd and alkaline systems, and 50% for saline batteries, with less than 5% of scrap as contaminant. This physical step can be considered as a pre-treatment of this type of waste material envisaging its valorization by chemical treatment, as improves the concentration of the elements of interest and decreases the iron content.

Jan 1, 2006

By Henrique Ventura Oliveira

Continuous casting is the most important process for solidification of steels. In this process, the fluid flow pattern in the tundish and in the mould have significant effect on the product quality. Problems associated to fluid flow in the tundish include surface turbulence, ?short-circuits?, formation of dead zones and vortexing. During grade changes, mixing in the tundish plays a significant role in determining the length of the intermixed slab. All these flow aspects can be studied by means of mathematical and physical models. In the last years, numerical simulation of fluid flow has become a very popular tool in the analysis of the performance of continuous casting tundishes. In setting-up these numerical simulations, special care should be taken in choosing the appropriate mesh distribution, the interpolation scheme, the adequate location of the inlet boundary and the turbulence model. In the present paper, turbulent fluid flow in different configurations of tundishes was simulated. Different turbulence models were used in the simulations. Residence time distribution (RTD) and mixing curves during grade changes were predicted and compared to results obtained in physical models. The performances of the different turbulence models were evaluated. For the tundishes that have been studied, the performances of the different turbulence models tested in the present work were similar. There is no evidence that any of the models provided sustained improvement when compared to the well-established standard k- model. All turbulence models tested presented limitations in simulating flows under low turbulent Reynolds numbers.

Jan 1, 2006

By Tang Mo-tang

A new process for extracting indium from indium-zinc concentrates was proposed in this paper. The process can directly extract indium from removed copper solution by P204, and cancel the stage of removing iron in the traditional process because of using iron and part of zinc in the In-Zn concentrates for direct preparing high quality Mn-Zn soft magnetic ferrites. The technologies in the processes, such as leaching the neutral leached residues with high concentrated acid at high temperature, reduction ferric and removing copper, and extracting indium, were investigated. The results showed that total recovery ratio of indium has been increased from less than 70% in the traditional process to more than 95%. This process has the advantages of largely simplifying the procedure of indium extraction, zero draining off of iron residue and zero emitting of SO2. So this is a clean production process.

Jan 1, 2006

By A. Cullaj

During a period of 15 years the metallurgical and chemical complex of Elbasan containing more than 15 principal plants, producing cast-iron, steel, coke, nickel carbonate, nickel, cobalt, chromium and other products, discharged into air, river water and soil an extensive amount of hazardous wastes containing high toxic substances. A monitoring study for the levels of heavy metals in soils nearby the former plant is carried out for the first time. Very high levels (total and extractable) of contaminants such as nickel, cobalt and chromium are found in samples taken from a relatively vast territory including the city of Elbasan, situated 8 kilometres far from the plant. The most polluted samples present a total content of 1211.8 ? 2949.6 mg/kg Ni, 97.0 ? 181.2 mg/kg Co and 1358.7 ? 4130 mg/kg Cr. These levels exceed several times the phytotoxic thresholds and present a potential hazard for the inhabitants. This study, as part of a bigger multinational project on solid decontamination, will also serve to the possible application of the new phytoremediation and phytoextraction technologies, being developed in parallel in this project.

Jan 1, 2006

By Wenjie Zhu

Hexavalent chromium is a widespread environmental contaminant. An Achromobacter sp. strain nominated Ch1 can reduce soluble and toxic chromate to insoluble and non toxic Cr(III) in aerobic cultures, and no Cr(VI) decrease was observed in anaerobic cultures. In contrast with other Cr(VI) reducing microorganisms, Ch1 showed higher Cr(VI) reduction at high pH. Reduction performed under alkaline conditions at pH 7 to 11, and the optimal pH was 10. During the reduction, pH decrease was observed may caused by production of acidic metabolic byproducts from aerobic respiration. In the present study, the ability of Achromobacter sp. Ch1 to reduce Cr(VI) during growth was evaluated with lactate as an electron donor. In NB medium, Ch1 reduced 100% of 24mM of Cr(VI) in 35h, but only 73% of 30mM of Cr(VI) after 48h of inoculation. Reduction was inhibited by metal ions like Ag+, Cu2+, Zn2+, slightly inhibited by Mn2+, and not affected by Mg2+. Results revealed that reduction rate of Cr(VI) also increased with the increasing of concentrations of lactate, and complete reduction was achieved at the concentrations above 40 mM. HPLC analysis demonstrated Cr(VI) reduction was associated with the consumption of lactate. There was a large quantity of dark blue sediment generated in the culture during Cr(VI) reduction by Ch1. Energy dispersive X-ray (EDX) analysis showed that the major element composed the formed sediment was chromium presented as Cr(OH)3 precipitate. The features characterizing Cr(VI) reduction by Achromobacter sp. Ch1 are high Cr(VI) concentrations and high pH.

Jan 1, 2006

By A. N. Lasseigne

Hydrogen storage capabilities of LaNi5 intermetallic compounds were investigated utilizing the combination of thermoelectric power, Beeghly Ester-Halogen digestion, and Leco hydrogen determination. Thermoelectric power has demonstrated a rapid hydrogen assessment capability and can achieve the equivalent of the pressure-composition-temperature (activity) diagram. Effective use of hydrogen storage materials occurs in the two-phase, alpha+beta region of the PCT diagram. A thorough assessment of the content of each phase in this two-phase region to optimize performance of the hydrogen storage materials is described. Practices using the combination of these three analytical practices for rapid characterization of LaNi5intermetallic alloys are discussed.

Jan 1, 2006

By A. V. Tarasov

One or more of the main alloying metals, i.e. copper, silicon, nickel, magnesium, zinc and other metals can form a composition with aluminum, by dissolving in the latter. The thermodynamic computations have indicated that within a range of temperatures from 700°C to 1300°C the reactions of molten aluminum with zinc and nickel oxides are shifted toward formation of free metals because it is possible to use the main alloying metals, i.e. zinc and nickel, in the form of inexpensive intermediate products and waste. The laboratory studies conducted have confirmed a possibility for production of aluminum alloys using intermediate products in the form of oxides of alloying metals.

Jan 1, 2006