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By Zhouhua Jinag

The attempt has been made to manufacture high nitrogen austenitic stainless steels by pressurized electro-slag remelting furnace with maximum nitrogen pressure of 7MPa. To obtain high nitrogen content in steels, the compound electrodes with different nitrogen sources (FeCrN, Si3N4) were prepared. Using the Si3N4 as the nitrogen alloying source, the silicon contents in ingots were prone to be out of the specification range, and the electric current fluctuated greatly and the surface qualities of the ingots were poor. The surface qualities of the ingots were improved using FeCrN as nitrogen alloying source. The sound and compact macrostructure ingot with the maximum nitrogen above 1.0wt% could be obtained. A series of high nitrogen austenitic stainless steels have been successfully developed by this method. The mechanical and pitting corrosion resistance properties of high nitrogen austenitic stainless steels were investigated. The results show that the steels exhibit excellent mechanical and pitting corrosion resistance properties.

Jan 1, 2009

By Rashmi Ramesh

Zinc oxide nanoparticles and nanostructures form an active area of research in the recent years. It can be doped to modify electronic, optical and other properties. Synthesis and characterization of zinc oxide is of extreme importance in order to understand the structure property relationship in this material which is now being considered of importance next to carbon nanotubes. Microstructure of zinc oxide nanomaterial is extremely sensitive to the preparation conditions. Nanocrystalline pure and Mn and Mg doped zinc oxide samples were prepared by wet-chemical method under different growth conditions. The samples were investigated for crystalline phase, microstructure, morphology and luminescence characteristics. The effect of Mn and Mg doping on the characteristics of ZnO have been discussed.

Jan 1, 2010

By H. Antrekowitsch

The decreasing quality of the input materials in copper recycling leads to a higher content of impurities in the anode copper. An improvement of the pyrometallurgical refining process is therefore necessary to produce high quality anodes for the copper refining electrolysis. The behaviour of the most important accompanying elements (e.g. nickel, tin, lead, zinc etc.) at different reaction conditions has to be investigated in order to improve the metal/slag reactions as well as the vaporisation by selective oxidation in the anode furnace. Therefore the thermodynamic conditions like reaction order and the activity coefficients at the copper refining process have to be known for the optimisation of this technique. Additionally the interaction between different elements has been investigated as a function of the temperature, the content of the elements and the slag composition especially for nickel. These investigations were done at the Christian Doppler Laboratory for Secondary Metallurgy of Nonferrous Metals.

Jan 1, 2005

By Lassi Klemettinen

For better understanding and maximal value utilization of the WEEE smelting process, the behavior and distribution of different trace elements must be known. In this study, the behavior of nickel as a trace element was studied in an equilibrium system with metallic copper—spinel saturated iron silicate slag (with 3 wt-% K2O)—iron aluminous spinel—gas. The experiments were conducted in alumina crucibles at 1300 °C, in oxygen pressure range of 10−10–10−5 atm. A time series of 15–60 min experiments was also conducted for investigating the formation rate of the primary spinel phase in the system. The results show that the distribution coefficient of nickel between metallic copper and liquid slag changes from approximately 70 to 0.4 along the increasing oxygen pressure range. In addition, a significant part of the nickel deports into the spinel phase. The spinel formation was investigated based on composition analysis results and visual observations from SEM-images.

By Jacques J. Eksteen

Any effort to improve the metallurgical control of industrial furnaces employed in the primary extraction of high carbon ferroalloys are bound to fail unless the variability of the melt is not fully accounted for. A number of sampling campaigns were performed on both 3phase AC submerged arc and single phase DC open arc furnaces at different smelter sites in South Africa where High Carbon Ferrochrome is produced. It was found that the heterogeneity between multiple samples during a single taps were much higher that for heterogeneity found within a sample. Moreover, this heterogeneity (as quantified by the relative standard deviation per tap) varied with the operating conditions of the furnace, the element monitored and the type of furnace. A relationship was found between the relative standard deviation of certain elements and the degree of subcooling of the melt.

Jan 1, 2006

By K. Morsi

The interest in spark plasma sintering has been growing considerable over the past few years. This has been brought about by the unique advantages of the process, which include reduced sintering temperatures and times and the production of materials with unique microstructures and properties. Despite its current reputation as an outstanding process that has solved major problems such as nano-powder consolidation, it has so far been largely limited to the manufacture of simple shapes, due to its inherent geometric configuration. In this paper we present preliminary results on spark plasma "extrusion" that can allow the production of extended geometries via electric-current processing. Preliminary results on the processing and microstructure of spark plasma extruded aluminum are discussed.

Jan 1, 2009

By Egil Aukrust

"An American Iron and Steel Institute Task Force evaluated developing direct steelmaking technology worldwide to seek a replacement for the coke-oven, blast-furnace, basic-oxygen process technology now in use. To remain internationally competitive it is essential to move away from the traditional series of batch processes towards continuous processing and the associated energy savings which are possible with high technology process control systems. The group identified in-bath smelting of iron ore pellets or fines with coal as the process most sui table for domestic raw materials (including abundant scrap) and called for research to study operation with varying degrees of preheat and prereduction of the ore by the gases generated from the coal and various degrees of combustion of these gases above the melt.A coordinated, 3-year, $27 million, direct steelmaking research program is proposed. Concurrent projects include design, construction, and experimental operation of an in-bath smelting pilot plant; modeling, simulations, and laboratory-scale experiments at universities on slag-phase and metallicphase reactions and interactions; and large-scale heat transfer and reaction rate trials. Also included are modeling studies and pilot plant trials of on-stream decarbonization and desulfurization; application of circulating fluid bed technology to fine ore reduction and hot gas cleanup; and specific heat transfer and fluid flow research projects.IntroductionThe American Iron and Steel Institute (AISI), based on the Task Force studying direct steelmaking, believes strongly that a coordinated program of research on the reduction of domestic raw materials to liquid steel should be undertaken as part of the Steel Initiative program. To specify the steelmaking process for development best suited to the American steel industry and domestic raw materials, it was important to determine the state-of-the-art of direct steelmaking worldwide, both as practiced and under development, and then, by expert analysis of the processes and their potentials, to choose the process most likely to provide a domestic competitive edge."

Jan 1, 1988

By A. Patti, S. Reutzel, D. M. Herlach, L. Ratke, I. Egry

Cu-Co shows a metastable miscibility gap in the region of the undercooled melt. Undercooling of the melt below the binodal leads to separation of the melt into a Co-rich LI-phase and a Curich L2-phase. Experimentally, undercooling into the metastable miscibility gap is realised by means of electromagnetic levitation (EML), processing in drop tube (DT) and by melt flux embedding. As undercooling is large in these experiments, the velocity of the solidification front is high and the microstructure is frozen in instantaneously. Samples have been undercooled and solidified in the TEMPUS-facility (container less electromagnetic processing under weightlessness) during parabolic flight under reduced gravity conditions. Microstructures of solidified samples have been analysed and compared to those processed under gravitational conditions. The influence of convection on phase growth is much lower in reduced gravity. The microstructure shows spherical droplets of the minority phase, statistically dispersed in the majority phase.

Jan 1, 2004

By Larry M. Southwick, Phillip J. Mackey, A. E. (Bert) Wraith, Albert Pelletier

In 1881, the first commercial pneumatic Bessemer-type converter treating copper matte was successfully introduced by Pierre Manhes at the Eguilles copper plant near Vedène in France. This development followed over a year of testing on a smaller scale at a foundry in Vedène, during which the vertical tuyeres of the conventional Bessemer converter had been successfully replaced by horizontal tuyeres in an effort to avoid the freezing of copper which had occurred in the bottom of the vessel having vertical tuyeres. The Manhes Converter, as it became known, was the first successful large-scale adaptation of the Bessemer concept of using compressed air blown into a melt for metal refining and treatment. Within a few years, Manhes Converters utilizing horizontal tuyeres in either the original type of vertical converter, or a later and more enduring horizontal barrel converter, were in operation at over a dozen copper smelters around the world. It was this process that Messrs Peirce and Smith essentially improved with the introduction of the larger converter which bears their name and the development celebrated at this Symposium. The present paper briefly traces the original development by Pierre Manhes in the early 1880s and which set the stage for the later Peirce-Smith adaptation. The paper observes that the original development by Manhes was in part driven by the need to reduce coal (energy) consumption and hence the production cost in order for Eguilles to remain competitive with the larger plants in Swansea, Wales, where a ready supply of cheap coal helped keep smelter treatment terms of the day low. These themes are eerily resonant of today where booming copper production in China has impacted the industry, and also where energy consumption, closely linked to today’s more familiar theme of ‘climate change’ remains an important challenge currently confronting the entire industry. The paper concludes with comments on these seemingly parallel situations today and offers some thoughts for the future.

Jan 1, 2009

By Igor Zh. Bunin

A model for developing electric discharges between sulfide mineral (pyrite) particles under high-voltage nanosecond pulses in a liquid medium (water) is considered. A possibility of electrical breakdowns of liquid gaps between particles under nanosecond pulses is shown. This probability and the energy released in discharge channels depend strongly on the sulfide conductivity.

Jan 1, 2010

By Qingwei Wang

Heavy metal-containing wastewater from hydrometallurgical processes of lead-zinc was treated by biologics in a 200 m3/h industrial scale experiment. The result shows that Zn concentration declined from 50.28 mg/L~240.81 mg/L to 0.21 mg/L~1.98 mg/L, Pb from 1.00 mg/L~13.47 mg/L to 0.083 mg/L~0.71 mg/L, Cu from 0.24 mg/L~2.38 mg/L to 0.059 mg/L~0.40 mg/L, Cd from 2.12 mg/L~23.47 mg/L to 0.011 mg/L~0.071 mg/L and As from 0.50 mg/L~6.00 mg/L to 0.005 mg/L~0.10 mg/L. The concentrations of the above heavy metals in the treated water were lower than that in Integrated Wastewater Discharge Standard (GB8978~1996) in China. Furthermore, the treated wastewater was recycled and reused in smelter plant. Zinc content in hydrolytic sludge reached up to 34.04%, which indicates that this sludge can be used to recover valuable metals.

Jan 1, 2010

By Linli Wu

During the measurement of contact angle, a misty band was observed near the substrate. Hsien-Nan Ho and Shinn-Tyan Wu thought this was because the oxygen atoms on the interface migrate to the droplet surface to form an oxide band near the substrate. But from our experiments misty band appeared before the drop reach to the substrate. Theoretically speaking, the oxygen partial was the same everywhere in the vacuum furnace. So there was no condition to provide enough oxygen forming oxide. This appearance would be explained more reasonably with the optics principle. Most reflected light would be absorbed by the substrate and the light cannot reach the observation area, so the misty band formed.

Jan 1, 2006

By Musa Karakus

The sedimentary iron ores of Alsace-Lorraine, France have very high phosphorous contents that average 0.7% and are as much as 2.19% P. Ores from the Tucquegnieux and Joeuf mines have been studied by cathodoluminescence microscopy, X-ray diffraction, scanning electron microscopy, and electron microprobe analysis in order to fully characterize the mineralogy, size, shape, and distribution of the deleterious phosphate grains. The phosphorous occurs as collophane, a carbonate fluorapatite, in ten morphological forms, most abundantly as microcoprolites, but also as intraclasts, concentric layers, and cortices in ooids, phosphate replaced ooids and bioclasts, phosphatiC shells, fossil infillings and internal molds, fish teeth, phosphatiC laminae, and cements between the goethite ooids. About 95% of the phosphate grains are sufficiently large that relatively fine grinding fol'lowed by reverse flotation would be expected to be effective in significantly diminishing the phosphorous content of the concentrates.

Jan 1, 1989

By José R. Parga

In some parts of the Comarca Lagunera with population of about 2.5 million people, situated in the central part of northern México, chronic arsenic poisoning is endemic and severe adverse effects attributed to As exposure have been reported. Lifetime exposure to arsenic will develop classical symptoms of arsenic poisoning such as skin pigmentation changes, gastrointestinal disturbances and neurological changes. There are several methods available for removal of arsenic from well water in large conventional treatment plants, however a very promising electrochemical treatment technique that does not require the addition of chemicals or regeneration is Electrocoagulation (EC). The EC operating conditions are highly dependent on the chemistry of the aqueous medium, especially conductivity and pH. In this study, Powder X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Transmission Mössbauer Spectroscopy (TMS) were used to characterize the solid products formed at iron electrodes during the EC process. This study will provide an introduction to the fundamental concepts of the EC method. Finally the results of this study suggest that the presence of maghemite and magnetite particles can be used to remove arsenic (III) and arsenic (V). In the field pilot plant scale study more than 99% removal of As species from groundwater is achieved.

Jan 1, 2005

By Liu Wei

In order to make clear the dissolving characteristic of the chrysocolla (CuSiO3?H2O) in the ammonia-ammonium chloride solution, a thermodynamic model of the chrysocolla (CuSiO3?H2O)-ammonia- ammonium chloride-water system is established using the exponential computation method based on both mass balance and charge balance equations. The equation group of the thermodynamic model is solved by the MATLAB Soft on PC. The condition which is favorable for dissolving high concentration of copper in solution is making out. The stable area of chrysocolla (CuSiO3?H2O) and the condition of chrysocolla (CuSiO3?H2O) converting to atacamite (Cu(OH)1.5Cl0.5) is also studied. A group of experiments are designed to validate the veracity of the results of the thermodynamic calculation.

Jan 1, 2010

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 Leon E. Laforest

An early commitment by Kidd Creek Mines Ltd. (formerly Texasgulf Canada) to follow a stringent environmental control programme from the initial stages of design and development of its metallurgical facilities in Timmins, Ontario, has resulted in the on-going attainment of extremely low levels of industrial waste emissions. This paper outlines the monitoring programme initiated and maintained by the company's environmental control section. Comparative results of environmental sampling for the periods before and after the copper smelter start-up are highlighted.

Jan 1, 1983

By M. J. Adam

As part of its research programs, the Bureau of Mines is investigating the partitioning of complex sulfide minerals to simpler sulfide phases by sulfidation reactions. Partitioning in this manner can afford opportunity to improve selective extraction of mineral constituents of value. This report describes research involving the sulfidation partitioning of the mineral pentlandite, which is an important source of Ni in primary production. For the laboratory studies, the pentlandite was synthesized in nominally equiatomic proportions of Ni and Fe. Elemental Ni, Fe, and S powders were blended, compacted, and sealed under reduced He pressure in vitreous silica tubes. The tubes were heated under controlled conditions at SOD? C for 24 h. The product was verified by X-ray diffraction and chemical analysis to consist essentially of (Ni,Fe)9S8. Small samples of the (Ni,Fe) S were encapsulated with sulfur in silica tubes at reduced He pressures and heated for 1 to 24 h at specific temperatures between 400? and 600? C, both below and above the boiling point of sulfur (_445° Cl. Reaction rate increased with temperature. Within this temperature range, partitioning to individual Ni and Fe disu1fides proceeded to essential completion according to the reaction

Jan 1, 1988

By Daniel K. Lindberg, Fiseha Tesfaye

To reduce the use of fossil fuels and increase self-sufficiency in energy, nowadays, there is an increasing interest to produce heat, power and transportation fuels from renewable resources. Solid biomass is one of the most important renewable energy sources for meeting this target. However, fouling, slagging, and corrosion threaten long-term operation availability and costs of biomass power plants. Slags accumulated on the surfaces of superheaters, which decrease thermal efficiency, often constitute a considerable percentage of complex inorganic phases. However, thermodynamic properties of the complex inorganic phases and their combined effect, which will help to deal with the slag related problems during high-temperature biomass combustion processes, are not well known. In the present paper, thermodynamic properties of K-, Ca-, and Na-based inorganic phases and their mixtures under different gas conditions are both critically reviewed and experimentally studied. The obtained results are presented and discussed.

Mar 1, 2017

By Zhongning Shi, Ramana G. Reddy, Min Li, Zhaowen Wang

Electrodeposition of cobalt from cobalt tetrafluoroborate (Co(BF4)2) was investigated using 1- butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquid. The experiments were conducted at 353 K. Chronoamperometry experiments confirm that the electrodeposition of cobalt on tungsten electrode proceeds via three-dimensional instantaneous nucleation with diffusion-controlled growth process. The average diffusion coefficient of Co(II) was found to be 7.5 × 10-8 cm2s-1 at 353 K, which is in good agreement with the estimated value from cyclic voltammetry. The electrochemical deposit was characterized using SEM-EDS and XRD methods. The SEM image shows formation of a dense and compact deposit at - 0.75 V. The EDS and XRD analysis confirm that the obtained deposit is pure cobalt metal.

Jan 1, 2015