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By Y. C. Avniel, T. E. Warner

"It is important to be able to measure sulphur and nitrogen in molten iron and steel on-line. Unfortunately, there are no solid electrolytes which are stable under oxidising conditions and in which the ions of these species are mobile. In this paper, novel applications of beta alumina electrolytes are described and the results compared with data in the literature. Excellent agreement was obtained confirming this approach as a viable method of detecting elements whose ions are not mobile in solid electrolytes.IntroductionIn the past two decades, the rate of many processes in steelmaking have increased substantially. The sophistication of chemical analysis has also increased but analytical equipment is frequently positioned a significant distance from the operating plant which dictates that time is spent taking a sample, sending it to the analytical facility, preparation of the analytical sample prior to insertion into the equipment. In many cases, the time taken for analysis can exceed the time taken for the actual process and is now the rate defining step. Furthermore, most analytical methods are unable to distinguish between the amount of element which is dissolved in the steel and that contained in precipitates. Even if the analytical equipment could separate these two, the distribution would have changed between the molten steel and the cast sample. It would be an advantage to analyse on-line for impurities in molten metals."

Jan 1, 1997

By Honglei Zhang, Yue Wang, Guotao Xu, Li Liu

The influence of rich oxygen atmosphere on the properties and structure of castables used in the hot wind pipe of blast furnaces was analyzed. Results show that the cold compressive strength of castables is affected by the change of rich oxygen volume in the wind pipe, the bulk density decreases and apparent porosity of castables increases with the addition of rich oxygen in wind pipe. With the addition of rich oxygen, the velocity of heat transfer increase and result of the steel shell become over hot out of safe limit at the thin lining in hot wind pipe.

Jan 1, 2015

By J. M. Figueiredo, A. R. Silva, M. C. Coelho, R. M. Guedes

"With the continuous depletion of conventional sources of non ferrous metals, low grade complex sulphide deposits have been regarded as an alternative source of supply of zinc, copper, lead and also silver and gold. In spite of very important efforts in research in this domain it is still a long way to go in order to achieve reliable technological solutions both in ore dressing and metallurgical treatments which enable these complex materials to be regarded as commodities. The RLE process to treat bulk concentrates such as those obtained from portuguese ores, under development at LNETI and QUIMIGAL premises, combines experienced unit operations and innovative configurations and is an effective contribution for the future use of these materials. The results of three years of experimental work and main conclusions on the overall feasibility of the process are presented.IntroductionIn spite of the very well-known problems associated to the development of complex sulphide deposits, the economical importance of the enormous reserves of these materials, widespread all over the world, is so evident that its future use as source of supply of basic and precious metals and other minor elements is almost unavoidable.Critical steps in that direction are mainly concerned with favourable economical conditions and sound metallurgical practice for the treatment of nonferrous metals concentrates, which are nowadays still considered as non-conventional raw materials.Since Portugal is one of the countries where these orebodies occur more extensively, Portuguese authorities have dedicated since the beginning of the seventies, a big effort on finding economical and reliable processes for the recovery of copper, lead, zinc and also gold and silver, and for this purpose, several alternatives on ore dressing and metallurgical processing were studied, however without full sucess.Five years ago LNETI, a research laboratory, and QUIMIGAL, a chemical company, both state owned, decided to launch a research programme for the development of a metallurgical process for the treatment of NFM concentrates, which received financial support from NATO under its programme ""Science for Stability""."

Jan 1, 1988

By Jilai Xue, Jun Zhu, GermainKouma Ndong, Luxing Feng

High-temperature corrosion behaviors of Fe-Ni-Cr alloy as inert anodes for aluminum electrolysis have been studied. The effect of anodic overpotential on layer growth of anodic surface is specially considered. The corrosion layers on the anodes tested were analyzed using XRD and SEM-EDS to provide a fundamental understanding of the layers growth at metallic anode surface. The dissolution of the scale layers on the metal anode occurred with low overpotential, while AlxM3-xO4 spinel phase within the scale layers was found with an increased overpotential. A mixture of multiple MyO layers existed on the anode substrate. The results may be useful for understanding and controlling the corrosion behaviors of Fe-Ni-Cr anode for potential application in aluminum electrolysis.

Jan 1, 2015

By Xin Zhang, Mengqi Li, Hongxu Li, Xinrong Zhang, Hao Bai, Ning Li

"Organic Rankin Cycle (ORC) is an effective technology to transform low-grade energy resource into electricity. In this paper, based on thermodynamic principle, considering the waste heat resource lower than 120°C, thermodynamic properties of ORC with working fluids ofR245fa, mixed R21/R245fa and mixed Rl52a/R245fa were assessed. The results show that high evaporation temperature contributes to improved system performance. The Rankine Cycle that uses R21/R245fa can increase net cycle output, thermal efficiency and exergy efficiency by 3.02%, 2.35%, and 4.44%,respectively, as compared to that with pure R245fa. When using Rl52a/R245fa as working fluid, the net cycle output can increase by 3.83% at most, while the thermal efficiency decreases by 8.7%. These results indicate that R21/R245fa has a good advantage in improving the cycle thermodynamic performance.IntroductionOrganic Rankine cycle is usually used for low temperature power generation, and is applied to the conversion of geothermal energy, low-temperature solar energy, ocean thermal energy and industrial low-temperature waste heat etc. Traditional Rankine cycle is quite mature already, however, organic working fluids would affect significantly the general efficiency of the entire thermodynamic system. Thus, selection of proper working fluids and development of new highperformance cycle is becoming important."

Jan 1, 2013

By J. N. Hryn

This paper describes some of the work done in Phase 1 of a multi-year, five-phase program aimed at demonstrating the economic feasibility of producing commercial-scale quantities of commodity materials derived from salt cake residue-oxide. The amount of salt cake generated annually in the U. S. is estimated to be 510,000 tons, including 340,000 tons of residue-oxide. Used beverage can (UBC) processing accounts for the majority of residue-oxiae that could be made available for further processing into commercial products. To characterize the composition of residue-oxide. eight residue-oxide samples from various secondary processors were obtained and analyzed. Surprisingly, the composition of residue-oxide was found to be independent of source or alloy family being processed, with? the exception of slightly elevated silicon levels in 3XXand UBC residue-oxide samples. Major phases detected in the residue- oxide were? alumina, spinel, and aluminum hydroxides. Preliminary economic analyses indicated that the refractory market appears to be the best choice for high value-added products produced from residue-oxide with minimum processing. Bench-scale tests indicated that low silicon containing residue-oxide is ready to enter this market, but the elevated silicon content of UBC and 3XX residue-oxide preclude this possibility. A separation technology should 'be developed to remove silicon-containing . species from the alumina and spinel values Present in residue-oxide. This technology would then allow UBC and 3XX residue-oxides to be converted to significantly higher value-added products.

Jan 1, 1995

By Guo Jun

In this study, BaTiO3 ultrafine particles surface-modified with stearic acid were synthesized by the hydrothermal method in a system of BaCl2-TiCl4-NaOH. The effects of NaOH/TiCl4 molar ratio, Ba/Ti ratio and time on structure and morphology of BaTiO3 ultrafine particles were investigated experimentally. The formation mechanism of different crystalline BaTiO3 particles was discussed, and it is considered that in a hydrothermal system, the main factors determining BaTiO3 crystalline are H+ replacement of Ba2+ causing H+ deficiency and anatase growth units involving in crystal growth, which clogs the axial channel for Ba2+ transference. By means of increasing the alkalinity of system and barium content, H+ deficiency and involvement of anatase growth units in crystal growth could be effectively controlled. The results show that when molar ratio of NaOH to TiCl4 is 9 and ratio of Ba to Ti 1.5, and time 8 hours, high purity tetragonal BaTiO3 ultrafine particles with a narrow grain-size distribution and nonpolar surface are obtained at 240oC. The particles have excellent flowability, which is ascribed that the surface polarity of barium titanium powder modified with stearic acid is changed and the interaction between the particles is weakened.

Jan 1, 2006

By Mao Chen, Tim Evans, Zhixing Zhao, Weidong Zhang, Baojun Zhao, Dongqing Wang

High temperature softening behaviours of iron blast furnace feeds (sinter, lump and pellet) have been determined under conditions simulated to the blast furnace. The industrial samples were packed with sandwich structure (coke / ore / coke) in graphite crucibles and 30 CO / 70 Ar gas mixture was blowing directly through the bottom of the crucibles. The displacement and temperature were continuously recorded simultaneously to construct the softening curves. Separated quenching experiments were also carried out at selected temperatures under the same gas atmosphere. The temperatures were selected corresponding to the turning points of the softening curves. The phase assemblages and composition of each phase in quenched samples were analysed by Electron Probe X-ray Microanalysis (EPMA). The proportion of the liquid formed at temperature was obtained from the backscattered electron images. The deformation characteristics of these complex multi-phase materials are shown to be related directly to the phase assemblages of the samples and the microstructures. FactSage was also used to assist the predictions of liquid / solid fractions and their compositions.

Jan 1, 2015

By Padmavathy Mahadevan, Samir Chefai, Eduard Guerra

"Electrocoagulation is a technique for treating wastewater streams from metallurgical plants whereby electrodes are corroded to generate gases (most notably oxygen at the anode and hydrogen at the cathode) and solid particulates which acts as substrates for coprecipitation of impurities. The performance of electrocoagulation reactors, in terms of their efficiency for removing a particular impurity, is highly dependent on several factors, most notably: the nature of the electrodes, the spacing between electrodes, the current density, the height of the electrodes, the solution flow rate, and application of periodic current reversal. Because these variables have complex interactions, in order to ensure reliable scale-up of laboratory results, experiments should be conducted under conditions that closely match those that would be employed at an industrial scale. To that end, this article describes the design and commissioning of a versatile laboratory scale electrocoagulation reactor that allows for the control of all the aforementioned variables along with the ability to measure the instantaneous spatial distribution of current within the reactor.IntroductionArsenic is often removed from metallurgical waste streams in stirred tank reactors by coprecipitating it with ferric ions as an arsenical ferrihydrite [ 1]. Electrocoagulation is an electrolytic technology that can accomplish the same task, but has not yet been widely adopted to treat metallurgical waste streams [2]. The electrocoagulation process involves the use of an external DC power supply to drive the dissolution of a relatively non-toxic metal into the wastewater stream, usually either iron or aluminum, which then largely precipitates as oxyhydroxide phases that adsorb undesired impurities [l]. At the anode, the metal is dissolved and oxygen is often evolved, lowering the local pH and enhancing metal ion solubility."

Jan 1, 2012

By K. Prashant Sarswat

Isotopes are critical to a variety of applications including physical science analyses, biology, medicine, pharmaceuticals, and national security. In most cases isotopes must be relatively pure or highly enriched before they become useful. Current isotope separation technologies are relatively inefficient, capital and labor intensive, and often produced by a limited number of suppliers. In the category of isotopes, lithium is among other important candidates. Lithium is found naturally in two isotopes, 6Li which accounts for 7.5% of all lithium, and 7Li which makes up the balance of 92.5%. Each of these isotopes is important to the nuclear industry. 7Li is often used in the form of lithium hydroxide which is used to control pH in pressurized water reactors. The current supply of 7Li is based mostly outside of the United States, and its long-term supply is uncertain. Apart from supply issues, the use of mercury for 7Li separation is also a concern in commercial processing using the most common and efficient approach [1–3]. Hence, a reliable, environmentally friendly, and efficient technique is needed to produce 7Li. In this line of investigations, the authors used a two-compartment system and significant separation was achieved. In this piece of research, some preliminary results are presented including cell design and actual isotope ratio after enrichment. Applying an electro-potential across two electrodes can be used to drive electromigration of Li isotopes. The electromigration is in addition to normal diffusion. Note that 6Li diffuses faster and hence there will be a lowering of the 6Li concentration near the positively charged electrode and an enhancement in 6Li near the negative electrode during the separation process. Similarly, 7Li will be more prevalent near the positive electrode and less prevalent near the negative electrode during the initial separation stage [1].

By Cyro Takano

An alternative use for recycling of waste from bag house of iron ore sinter plant was tested by producing and evaluating" at laboratory scale, the self reducing cold bonded pellets. This waste was characterized and the self-reducing pellets were produced using anthracite coal fines as reductant and Portland cement or hydrated lime/Blast Furnace slag as binder. It was used the molar ratio of Fe2O3/C (fix) equal to 3. Evolution of cold strength with curing time, for different contents of binder, was evaluated. Cold strength of 200N/pellet was obtained, for sinter dust, after 10 days of curing. Suitable hot strength was also presented and no decrepitation and swelling were observed. Good fractional reduction was obtained at 950°C and 1137°C. These results show that this material may be used by the Self-Reducing Processes for hot metal production, as an alternative route for this dust destination.

Jan 1, 1996

By Carl C. Nesbitt

A study was conducted to investigate the claims of early observers who noted an increase in the rate of gold dissolution when chlorine was chemically produced in the leach vessel compared to sparging with chlorine gas. This "nascent" chlorine was presumed to be an active intermediate in the production of chlorine (C1,l from chloride ions. The study used UV light to produce an activated chlorine atom intended to recreate the observed increase in the gold dissolution rate. Although no change in the kinetic rate was observed, the reaction mechanism by which chlorine reacts with particulate gold was instead determined. Various concentrations of multivalent cationic chloride salts were added to the leach solution to demonstrate that the increased dissolution rate was due to the increased concentration of the chloride ion and ionic strength of the solution.

Jan 1, 1992

By Dao Su, Kelang Mu, Yufeng Guo, Jinghua Zeng, Tao Jiang

"The influence of high pressure roller grinding (HPRG) on sintering of iron concentrate fines was investigated. Results of mini-sintering tests showed that assimilation temperature of iron concentrate fines decreased from 1230 ? to 1220 ? and assimilation time was shortened from 10 min to 5 min when the iron concentrate fines was pretreated by HPRG. Sinter pot tests showed that the yield of sinter increased from 60.33% to 72.92% , tumble index increased from 44.35% to 46.66%. The investigation indicated that, after being pretreated by HPRG, iron concentrate fines are improved in ballability and the fraction of fine particles increased, resulting in the improvement of granulation property and reactiveness in solid state reaction. As a result, sintering of iron concentrate fines were strengthened.IntroductionWith the rapid development of iron and steel industry and the decrease of high-grade ores, the imports of iron ore are increasing continually. It is of immensely strategic importance for development of iron and steel industry and energy security in our country to make good use of iron concentrate fine which is low price, high grade and has a refractory sintering property. When iron concentrate fine is used in sintering, granulation property of sinter mixture and permeability of sinter bed get poor. As a result, yield and quality of sinter fall down. Many researches show that, when HPRG is used in pelletization, quality of pellets is improved dramatically. Meanwhile, HPRG has a low energy consume, a large handing capacity and it is benefit for environment protect. At this theme, strengthening of sintering of iron concentrate fine pretreated by HPRG was investigated in this paper."

Jan 1, 2012

By R. Boom, C. F. Balentina, J. H. L. Voncken

During vitrification of bottom ash generated from the combustion of municipal solid waste (MSW), a Fe-Cu based alloy phase with great value was formed. In order to find proper commercial use in metallurgical industry, it is necessary to separate Cu and Fe. The present study focuses on the sulfide treatment at temperatures of 1400 – 1500oC, in particular with FeS containing minerals. Various sulfide compounds such as Na2S, Al2S3 and Ni3S2 were added to promote the copper removal. Pyrite and zinc sludge (containing ZnS) as waste streams were studied with specific interests. The results showed that both zinc sludge and pyrite are effective for copper removal with the highest removal efficiency of 95% by using pyrite. The copper content drops from 12 wt% to about 2 wt%. However, it is still difficult to remove copper completely from the alloy in one step, and a multi-step operation is needed.

Jan 1, 2008

By G. Brooks, J. Naser, M. A. Sattar

CFD models have been developed and numerical simulations have been carried out to predict the formation of foam in oxygen steelmaking. Foam was considered as a separate phase comprising a mixture of gas and liquid. Bubble break up and coalescence models have also been incorporated in a CFD model to predict the number density of individual bubble classes. A population balance equation was used to track the number density of each bubble class. Decarburization with heat generation from chemical reactions was integrated in the process. User subroutines were written in FORTRAN to incorporate the foam formation, the bubble break up and coalescence rate and decarburisation in the main program. The model predicted the foam height, bubble number density, velocity of phases, decarburization, and turbulence. The result from the model has been compared with available data from literature and found to be in reasonable agreement with the experimental and plant data.

Jan 1, 2014

By S. I. Sobol

The results of the study of the mechanism of a cathode process of cobalt electrolysis to explain disagreements in a form of kinetic equations of autoclave reduction of nickel and cobalt have been used.

Jan 1, 1993

By Shujian Jia, Mingming Song, Gaoyang Song, Bo Song, Yuhou Yang

An innovative method is investigated to separate inclusion particles from liquid metal by super gravity. To make clear the characteristics of the inclusion separation, Al melt containing MgAl2O4 particles with diameters less than 150 μm has been treated under various super-gravity fields. The thickness of particle-accumulated layer formed at the bottom of the sample and the area fraction, number density and size of inclusions were measured. It is found that the thickness of the particle-accumulated layer decreases and the area fraction of particles at this location increases with the increase of super-gravity field. With the gravity coefficient G=500, time t=2 min, and temperature T=1023 K, it is hardly to find any solid particles in the upper and middle areas of the sample and the separation efficiency is up to 90%.

Jan 1, 2015

By Rajesh S. Ransing

An intelligent tool has been developed to analyse the quality of diecast components. The influence of both design and process parameters has been studied in great detail. The tool, based on expert systems related technologies, can identify the causes for the defective castings manufactured. Design related causes such as gate position; gate area, runner design etc. as well as process related causes such as cycle time, cavity filling time and melt temperature are suggested by analysing the data on defective castings for a manufacturing campaign. This intelligent analysis is useful for both design as well as production engineers in the decision making process. All the causes for the occurrence of defects are classified into two categories. The firs category is the 'rootcauses' i.e. the causes which are related to the actual process, material and design parameters and which can be directly monitored. The second category is more abstract in nature and is classified as `metacauses'. These capture the scientific rationale implicit in the cause and defect relationships. This knowledge on causes and defects is represented in the form of a structured graph rather than by a set of rules, which, coupled with forward reasoning and heuristic search techniques results in an elegant and efficient approach. Uncertainties and the degree of relationship among causes and defects are represented by a fuzzy probabilistic model.

Jan 1, 1994

By Hideki Yamamoto

A new technology to convert fluoride gas (C2H2F4 : R-134a) contained in the exhaust gases from semiconductor manufacturing plants and refrigerators directly into a harmless substance have been established, thus, presenting a new concept for the disposal of fluoride gases such as CFCs that are associated with the global warming. Experimental results verify that chemical reactions with metal compounds can take place at substantially lower temperatures of 700- 800K as compared with combustion treatment temperatures of 1200-1500K. The reaction product is mainly metal fluoride, which chemically is a harmless material. Furthermore, this process is compact, easily controlled, safe and has low running costs. This paper deals with a new chemical reaction method for the harmless disposal of gases effecting the global warming.

Jan 1, 2003

By Leah Penner, Thomas J. Ruth, Paul Schaffer, François Benard, Edouard Asselin, Stefan K. Zeisler, Thomas J. Morley

"This paper details the electrodeposition of metallic molybdenum from an aqueous, acetateelectrolyte containing molybdate ions. The deposition is carried out in a highly concentrated (up to I 0 M) acetate bath in the presence of a very low concentration of bone glue (60 µg/L). The molybdenum metal deposits are up to 20 µm thick and adherent. The deposits were characterized by XRD and XPS analysis. The deposition process is very inefficient, as up to 99% of the current is used to generate hydrogen during electrolysis. The effect of acetate concentration, pH, additives and current on the deposition efficiency and physical properties of the molybdenum deposit were investigated and optimized to obtain smooth, adherent coatings.IntroductionMolybdenum has increased thermal and wear resistance properties that are often utilized in material coatings [I]. These coatings are most often manufactured by sintering, pressing or spraying molybdenum powder at elevated temperatures, as a substitute method for standard metallurgical practices, such as electroplating [2, 3]. The lack of reports describing molybdenum deposition is most likely due to the highly oxophilic nature of molybdenum and the stability of its oxides, especially in water. Previous attempts to electrochemically reduce molybdenum from molybdate (Mool·) ions to molybdenum metal have reported the production of either a poorly adherent mixed oxide [4-6], or a thin(< 0.1 µm) metallic film [7-9]. Thick metallic molybdenum is capable of being co-deposited with one of the iron-group metals (Ni [10], Co [11] and Fe [12]) to produce an alloy [13, 14]. These alloys, however, may not be suitable for applications requiring pure molybdenum as they usually contain less than 50% molybdenum (often less than 30%)."

Jan 1, 2012