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By Qiang Zhong, Bin Xu, Qian Li, Yong-bin Yang, Tao Jiang, Yan Zhang

The occurrence of different ringing behaviors in oxidized pellet kiln for two kinds of coal (A and B) with similar properties, is difficult to explain based on the relationship between kiln ringing and coal properties. In this paper, the interaction of coal ash with pellet scrap powder was considered by studying the cohering behavior of powders consisting of them. The results showed that the cohering briquette strength of pellet scrap powder increased considerably when mixed with a small amount of coal ash; a maximum could be reached when the mass percent ratio of coal ash was 1.5%; the strength of powder mixed with coal B ash was always higher in same firing system. This obviously illustrated that coal B caused a more serious ringing problem. The relevant mechanism was that the stronger reactivity of coal B ash made cohering briquette have a more perfect crystallization and a more compact structure.

Jan 1, 2015

By J. Bostjancic

As wastewater discharge regulations become more stringent, power plants, manufacturing plants and other industrial sites are looking for ways to reduce makeup water requirements and to recycle and reuse as much wastewater as possible. In some cases, environmental regulations require zero liquid discharge, meaning all wastewater must either be retained on site or reduced to solids for disposal off site. Zero liquid discharge or "closed-loop" wastewater treatment systems using evaporators and other process equipment have been well-accepted in recent years. Often overlooked is the fact that zero discharge is not just the latest fashion--many commercial zero liquid discharge systems have been in operation since the mid-70's. This paper will give specific examples of zero liquid discharge operations from 1974 to the present, showing how evaporation equipment and processes have changed to meet the requirements of industry and environmental regulations.

Jan 1, 1996

By Dominik Hofer

A broad spectrum of tantalum containing input materials can be processed for the production of synthetic tantalum concentrate (“SynCon”). The use of these low grade substances offers a secure alternative to mining of coltan in Central Africa. SynCon is produced in a multi-stage pyrometallurgical process, wherefore the melting behaviour of slags presents an important factor especially regarding the energy consumption and its optimisation. The characteristics of a slag comprising mostly Al2O3, CaO, SiO2 and MgO are influenced by the amount of other oxidic constituents which enfolds the main focus of this study. A hot stage microscope serves for the investigation of the slag behaviour in a temperature range from 1000 to 1600 °C under reducing atmosphere (CO/CO2 gas). The experimental results are compared with thermodynamic calculations (FactSage) to get a better understanding of the process.

By Fabio J. Esper, Wildor T. Hennies, Guillermo R. Martín-Cortés, Francisco R. Valenzuela-Díaz, Antonio J. Santana de Araujo, Maria G. Silva Valenzuela

Seeking to replace carbon-black as filler of rubber in the production of vulcanized goods, researchers from University of São Paulo have studied different materials types as minerals, vegetal or wastes agricultural and industry. Results of rubber composites filled with MA1 a waste of mineral treatment provided by Esper Industries are presented. MA1 was characterized through X-ray diffraction; Thermal analysis; Scanning Electronic Microscopy; and others laboratory methods. The composite and shaped masses were evaluated by these methods plus their mechanical properties such as tensile strength, elongation at break and hardness. Exceptional results were obtained in the mechanical properties evaluated, better than those obtained with the traditional carbon-black. Seeing the kind of material used as filler, it can conclude that the environmental benefit is present, as well as economic development, giving credibility to the use of these alternative material in replacement carbon black.

Jan 1, 2015

By Xiang Zhu

Xidagou is the largest waste water discharge channel of the Anshan Iron and Steel Complex (AISC) with average flow rate of 8000 cubic meters per hour, which is about 75% of the total effluent of the AISC. The waste water from Xidagou seriously polluted the Taizi River Basin. In order to meet the Chinese Class V Standard for Surface Water Discharge and the Standard for Recycled Industrial Water Reuse, with the aid of the World Bank, the AISC began the treatability studies in 1991. Based on the bench-scale test, the AISC carried out pilot-scale treatability studies on three different treatment processes and five different chemical coagulants for more than half a year in 1992. The study results show that the processes of primary sedimentation- chemical mixing and flocculation-secondary sedimentation-filtration can meet the requirement and that PFS and PAM are effective and economic chemical coagulants.

Jan 1, 1994

By Dengfu Chen, Yunwei Huang, Mujun Long, Kui Lv, Pei Xu, Lin Bai

The surface temperature of continuous casting slab in the secondary cooling zone is a key parameter of production control. However, the accuracy of radiation temperature measurement of high temperature casting slab is greatly affected by the environmental factors, such as water vapor, spray, water film and other participational medias during continuous casting process. In this paper, the radiation characteristics of water vapor and its influences to radiation temperature measurement of continuous casting slab were investigated. Based on the database HITRAN 2004 and the measuring principle of monochrome thermometer & colorimetric thermometer, the measuring errors under different operating infrared spectral wavelength were compared. Results showed that spectral region with wavelength nearby 1.0μm or 1.6μm would be the optimum for high temperature infrared thermometer used under the conditions with moist steam, water spray and water film at the secondary cooling zone in steel continuous casting.

Jan 1, 2016

By Zhan Jing

Keywords: thermodynamic, Ni-Co alloy powders, composition, fibrous The mathematics model of Ni(II)-Co(II)-C2O42?-NH3?H2O-H2O of thermodynamic equilibrium system has been developed theoretically according to the law of conservation of mass and the law of simultaneous equilibrium, and the logarithm concentration-pH (log[Me2+]T-pH) diagrams of this system have been made. The effect of ligand and pH value was studied. Two issues in coprecipitation route to synthesize fibrous nickel-cobalt alloy precursor powder, com-position and morphology which are a first priority, are addressed based on thermodynamic analysis and experiments. The results show that suitable pH value range of coprecipitation of nickel ions and cobalt ions in theory can be obtained to maintain fibrous, excellent compositonal homogeneity and stoichiometry in coprecipitation products. Experimental demonstration is also carried out.

Jan 1, 2005

By Jin Qiu

Experiments were performed to determine the extent of minor element elimination that occurred when mixtures of copper smelter dust and copper concentrate, were calcined under vacuum. Almost complete removal of the As, Sb, Bi and Pb occurred due to the conversion of the minor element compounds of these elements into their highly volatile sulphides by reaction with sulphur from the concentrate. Heat and mass balance calculations of the slag-blow in a copper converter found that ~30 tonnes of the vacuum calcine could be used to produce 100 tonnes of copper as white metal. The use of dirty concentrate as the sulphidizing agent in the vacuum calcination means that the minor element treatment capacity of the smelter complex could be increased by 60 %. Also the productivity of the converters may be increased by up to 8 % due to the supply of copper values and oxygen in the calcined mixture.

Jan 1, 2005

By Spencer Peng, Larry Wasik, Akram Alfantazi, Michael Mahon

A dynamic simulation of a zinc tankhouse is a potential tool to improve tankhouse production and cost efficiencies. A fully dynamic simulation has potential uses in the design of new tankhouses as well as in the optimization of existing facilities. Equations from previously validated models of a single cell have been adapted to the industrial dynamic process simulation software, CADSTM Plus. Based on the inlet concentration, current density, and electrode setup, the simulation can predict many parameters, including outlet concentrations, flow rates, current efficiency and energy consumption. Multiple cells have been simulated simultaneously, allowing for an entire hypothetical tankhouse to be modeled. The simulation can be used to dynamically predict the conditions in a zinc tankhouse throughout an operation time scale. Further applications of this model include, tracking impurity buildup, modeling of recycle streams and the development of new flow regimes within the tankhouse.

Jan 1, 2012

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 Murray Johnston

New measurements have been made on the equilibrium distribution of selenium and tellurium between molten slag and metal phases. Distribution coefficients of Se and Te between magnesia-saturated calcium ferrite slag and copper or silver alloys were measured over the temperature range 1473 and 1673 K under controlled oxygen patrial pressures of 10-11 to 10-0.68atm. The results demonstrate that the minor elements are present in the calcium ferrite slag as the selenide (Se2-) and telluride (Te2-) respectively, up to a PO2 of 10-6 atm. As conditions become more oxidising, Te undergoes a transition to the divalent oxide whereas Se does not. Increasing the temperature was found to enhance partitioning of the minor elements to the slag. In terms of activities, at 1573 K, Se showed strong negative deviation from the ideal behaviour in the slag, while Te showed only slight positive deviation.

Jan 1, 2006

By M. A. S. Siraa

A program of work was undertaken at the Kennecott Smelter and Refinery to model the complex. This effort contributed a total of eight models of the plant: flash smelting furnace, flash converting furnace, slag concentrator, anode furnace, offgas scrubbing system, acid plant, hydrometallurgical dust treatment plant, and the precious metals plant. Some of these models have been used in a variety of investigations ranging from offgas capacities for a steam generation analysis to an examination of impurities. The culmination of this enterprise has resulted in an on-line control scheme for the flash smelting and flash converting furnaces. These two process control schemes incorporate their respective steady-state heat and mass balances that are executed in response to feed changes while a feedback loop calculates when product grade and temperatures deviate from setpoints. This system has been put into place to improve furnace control and on- line time.

Jan 1, 1999

In the new flowsheet for Inco Limited's S02, Abatement Project at the Copper Cliff, Ontario operations, a copper/nickel sulphide flotation concentrate will be flash smelted, then converted to Bessemer matte. As in current practice, this will be slow-cooled and separated into components by magnetic separation and flotation. The copper content will emerge as a chalcocite concentrate (impure Cu2S), containing some nickel. This copper sulphide will be converted to copper metal.

Jan 1, 1993

By T. S. Montgomery

The performance of carbon-magnesia brick in electric arc furnaces (EAF) is interpreted in light of their observed optical microstructures. Features at the bricks' hot faces were protruding periclase grains, metal globules, graphite-metal contacts and linear void patterns. These features were com-pared to similar features previously seen from microstructures of basic oxygen furnace (BOF) refractories. Modes of formation were sought; an attempt was made to interpret their influence related to wear mechanisms.

Jan 1, 1982

By P. Sergi

A method of characterizing gold ores with respect to processing is proposed. The method includes microscopical examinations to obtain qualitative and quantitative data that relate to processing. The main thrust, however, involves laboratory heavy liquid separation tests, laboratory amalgamation tests, and laboratory cyanidation tests to determine the proportions of gold that can be recovered in a conventional processing operation. Two different Brazilian gold ores: a quartz vein gold ore, and gold in metasediments were tested.

Jan 1, 1989

By M. D. Crites

As part of a multi-year program for assessing the viability of chrome-free refractories in copper smelting, converting and refining furnaces, dynamic corrosion tests have been conducted on a series of refractories from the magnesia-alumina system, using a ferrous silicate slag. The corrosion rates of the test refractories are compared with those of a reference mag-chrome brick, and recommendations are made for more in-depth evaluations of the more corrosion-resistant materials.

Jan 1, 1999

By Leonid M. Lerner

High temperature aluminum Alloy 8009 is a rapidly solidified/powder metallurgy aluminum-iron-vanadium-silicon alloy. This alloy in combination with hard oxide aluminum film has unique engineering properties which may recommend its use in compressors and impellers for aerospace applications. Various anodizing processes (including Sanford Low Voltage DC+AC Process) for these task will be evaluated and normal chemical composition, physical properties, and macrostructures of 8XXX aluminum alloys will be presented.

Jan 1, 2006

By M. Neises, M. Roeb, C. Sattler, S. Stenger

"A two-step thermo-chemical cycle process has been developed and investigated. It is based on metal oxide redox pair systems, which can split carbon dioxide as well as water molecules by extracting oxygen atoms and reversibly incorporating them into their lattice. If concentrated solar radiation is used as the heat source, a promising method exists to produce synthesis gas from water and CO2. An easy way of operation is gained by the combination of a ceramic substrate as the absorber structure, which can be heated to high temperatures with concentrated solar radiation, and of a metal oxide coating which is capable to carry out the redox reactions. The performance and kinetics of a ferrite based redox material coated on ceramic substrates were investigated in a laboratory set-up. CO2 could be reduced with significant conversions. In addition, several side reactions were observed like the formation of carbon and like the Boudouard reaction.IntroductionThe search for alternative energy carriers and for processes able to reuse carbon dioxide stimulates the research for sustainable routes of alternative fuel production. In the scope of this search thermo-chemical processes combined with sources of concentrated solar energy have become more and more attractive. Ideally, the only raw materials for such processes are water (H2O) and carbon dioxide (CO2) enabling not only a process free of emissions, but also allow to reduce emissions of other processes by reusing CO2 to provide synthesis gas, which itself can be applied to produce chemical commodities or even better synthetic fuels like methanol or petrol.In contrast to the direct splitting of those raw materials, thermochemical cycles split water and CO2 in several steps and enable hydrogen (H2) and carbon monoxide (CO) generation at temperatures controllable by today’s technical equipment. One of the most interesting thermochemical cycles is a two-step process using metal oxide based redox systems. During the first step of this cycle (the regeneration step) the metal oxide is reduced setting some of its lattice oxygen free according to reaction (1). In the next step (the splitting) the reduced and activated material is oxidised by withdrawing oxygen from water and CO2 and at the same time hydrogen and CO is set free according to reactions (2a) and (2b) respectively."

Jan 1, 2011

By F. H. Froes, O. N. Senkov, N. Srisukhumbowornchai

"Mechanical alloying (MA) and thermohydrogen processing (THP) approaches were used to synthesize amorphous or nanocrystalline powders of the titanium-aluminide-based alloys and composites. Fully dense samples with nanocrystalline and bimodal structures were produced from these powders by hot isostatic pressing. The stability of the microstructures during continuous heating at high temperatures was studied. Characterization techniques including X-ray diffraction, scanning and transmission electron microscopy, energy dispersive spectroscopy, and differential thermal analysis were used in this work.IntroductionAs performance demands increase, so do the demands for enhanced mechanical property combinations at reduced overall weight; and reduced weight can most efficiently be realized by the use of low-density metals with high specific strength, such as titanium alloys and titanium-aluminum intermetallics [l]. The TiAl-based alloys are attractive for high temperature applications, however, they exhibit poor ambient temperature ductility and fracture toughness [2-4]. Incremental improvements can be obtained using ingot metallurgy processing [1,2] but more substantial developments require ""far from equilibrium"" (FFE) synthesis [5-8] which allows development of novel constitutional and microstructural effects, leading to enhanced physical and mechanical properties. Improved ductility of titanium aluminide intermetallics can be achieved by disordering, grain refinement and deoxidation of the matrix, while good elevated temperature properties are achieved due to a dispersion of fine, thermodynamically stable, second phase particles.The approaches for producing nanocrystalline and amorphous TiAl-based alloys and composites used in this work included FFE powder metallurgy techniques such as rapid solidification, mechanical alloying and thermohydrogen processing. The rapid solidification (RS) technique allows extension of solubility limits, production of novel phases, and much more refined microstructures (down to nanostructure or even amorphous range) than is possible using the ingot metallurgy technique [9]. Mechanical alloying (MA) is a process in which heavy working of powder particles results in intimate alloying by repeated deformation, fracturing and welding. This process can produce greater departure from FFE than RS, leading to greater refinement effects; and additionally allows production of a dispersion of second phase particles [10]. Thermohydrogen processing involves hydrogen as a temporary alloying element in titanium to facilitate processes, refine microstructure, and improve final mechanical properties [11]; it was used in the present work to improve MA process. The combination of these three processes was expected to control the final microstructure even better than either process used alone."

Jan 1, 1998

By Bing Hu, Zhu-Cheng Huang, Guang-Bin Xia, Hu Peng, Hua Wang

"The temperature rising characteristics and reaction of the reduction of iron oxide pellets with anthracite fines were studied using a MW-L0316V microwave oven and Leica-DM-RXP polarizing microscope. The results show that iron oxide pellets and anthracite fines have good microwave absorbing properties, and high temperature and reducing atmosphere in a relatively short time for reduction of iron oxide pellets can be achieved. The reduction reaction, which follows the unreacted core model, is rapid and the metallization increases from 13.41% to 56.57% as the reduction end point temperature increases from 850oC to 950oC. The iron is formed, fine grain crystals of iron are transferred and the contraction of metal phase occurs firstly at the surface of pellets, which hinders the reduction reaction at the center of pellets. The rate of reduction reaction increases slowly as the reduction end point temperature increases from 950oC to 1050oC.IntroductionIron ore direct reduction can be divided into gas-based reduction and coal-based reduction. Owing to the effect of the resource and the related economic benefits [1, 2, 3, and 4], the development of gas-based direct reduction technology is restricted, but the development of coal-based direct reduction supported by the relevant industrial policy has very good prospects for application.As a source of clean energy, in China microwaves have been applied in many fields [5, 6, and 7]. Chen Jin studied the reduction of carbon pellets under microwaves, and has made some progress on reduction kinetics and reaction mechanisms. Other countries also have related research in this field [8 - 15], for example, Kotaro Ishizaki and Kazuhiro Nagata have done research on the reduction reaction of carbon magnetite heated by microwaves. The research shows that Fe3O4 is deoxidized to FeO at about 800oC, and FeO is deoxidized to Fe at 1000oC-1025oC. Due to the very good heat absorbing properties of iron oxide pellets and anthracite fines, the selective and rapid heating of microwaves can rapidly raise the temperature of pellets and anthracite, and the iron oxide pellets can be rapidly reduced. In order to provide enough theoretical basis for direct reduction by microwave heating, this paper studies the temperature rising characteristics, behavior of the reduction reaction and the changes of the iron oxide pellets and anthracite in the microwave field."

Jan 1, 2011