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By M. O. Lai

"Metal matrix composite (MMC) with composition of Al-4.Swt.%Cu reinforced by IOwt.%TiB2 or ISwt.%SiC particulate has been successfully fabricated using powder metallurgy technique. Disk, compression and beam specimens were prepared with (a) layered structure containing ductile Al-4.Swt.%Cu with brittle Al-4.Swt.%Cu/TiB2 or Al-4.Swt.%Cu/SiC layers, and (b) homogenous constituent with composition of Al-4.Swt.%Cu/lOwt.%TiB2' The specimens for the fracture toughness measurement were built through three ductile-brittle-ductile alternating layers. For the beam specimens, the layers were built through brittle-ductile-brittle sequence. The brittle layer consisted of Al-4.S%Cu with fixed amount of reinforcement. Fracture toughness testing revealed an increase for layered composites although the total amount of the reinforcement was the same for all disk specimens. The increase in fracture toughness is due to the existence of ductile layers which manifests a strong influence on delaying the occurrence of fracture. It acts as a barrier to resist the propagation of crack and hence increases the fracture toughness of the layered MMC specimens, Delamination in the beam specimens was observed to be due to shear stresses. Fracture surfaces of both disk, compress and beam specimens were characterized using the SEM. IntroductionMechanical and thermal properties can be achieved by the incorporation of refractory secondary phases to constrain the plastic flow of the matrix in a metal matrix composite (MMC). The size of the reinforcement particulate incorporated must be in the range larger than the dislocation cell size and strongly bonded to the matrix (I). Particulate reinforced metal matrix composites hence provide high modulus, improved wear resistance and strength (2-4). Because of the incorporation of refractory phases which are generally brittle, the major limitation in the mechanical properties of MMCs is their limited ductility in comparison to their base metals. Cracks normally initiate from the reinforcement and voids (4, 5). Due to the lack of ductility, cracks propagate rapidly with increase in load. As a result, the interactions between reinforcement particles and propagating cracks have recently been of great research interest (6). In addition, volume fraction of reinforcement and aging condition of the matrix significantly affect the mechanical behaviour of MMCs. In the case of AI-3.5%Cu reinforced with varying volume fractions of SiC particulate, it has been found that the probability of particle fracture increased with increasing volume fraction of reinforcement (7)."

Jan 1, 1996

By Gerhard Meyer

A new instrument for the determination of iron., zinc, calcium, and other metals independently directly in the fumes emitted from steelmaking processes is described. Based on the well- accepted method of X-ray fluorescence, the instrument can detect numerous metals simultaneously in the fume as well as report their concentration on a mass per unit time basis real time to a control room computer. The instrument mounts on the wall of the fume duct and can., via a small opening, directly view the hot exhaust plum inside the duct. The concentration of metal in the fume over time has been shown to change dramatically depending on process variables. Variables such as oxygen flow rate, lance height and nozzle configuration., slag condition., and episodic scrap addition can affect the presence of metal particles and fume in the exhaust. An analysis response time of 6 seconds enables better control of the steelmaking process thereby conserving primary resources and reducing environmental impact.

Jan 1, 2001

By T. Nagano

Mitsubishi Metal Corporation started the development work of a new process for continuous production of copper in 1961. After a series of experimental and semi-commercial operations, the first commercial plant of the Mitsubishi Continuous Copper Smelting and Converting Process was put into operation in March, 1974. The new plant, which has a design capacity of 4,000 metric ton copper per month, was built within the premises of Naoshima Smelter, replacing the old No.1 reverberatory smelter there. The SO2-rich exhaust gas from this new plant is blended with the off-gas of the No.2 reverberatory furnace for production of sulfuric acid and the overall emission of sulfur at Naoshima has been greatly reduced. The operation of the continuous plant has been satisfactory and several advantageous features of the Mitsubishi Process have been proven on a commercial scale. This paper first gives a brief description of the history of the development work and the characteristic features of the process. The paper then describes the new commercial plant and operating data obtained so far.

Jan 1, 1976

By Jiann-Yang Hwang, Ying Qin, Shu-Jing Zhu

Metallurgical Oil Sludge (MOS) is a byproduct created in the process of steelmaking. More than a million tons of MOS are generated each year throughout the world. The material contains hazardous components such as heavy metals and pathogenic organics, which can cause serious environmental problems and health issues. Landfill, combustion, and pyrolysis have been investigated for the disposal of MOS. However, these methods are unsatisfactory since they are unable to reach the clean environment goal. In this study, we investigate the possibility of using MOS as a reductant in a high temperature metallurgical process. The results are reported and discussed.

Jan 1, 2015

By R. C. Nascimento

It was investigated the effect of the addition of bentonite on the physical propertiesof pellets produced from fines of manganese ores. Cold-bonded pellets were produced. Pellets bearing up to 1 wt% of bentonite were submitted to strength compression resistance tests, fatigue of pellets to impact and maximum height of fall tests. A correlation of resistance of the pellets and time for curing were stablished. The produced pellets match the conditions for raw materials used in electric smelting hrnaces to produce manganese based ferro-alloys.

Jan 1, 1995

By J. B. Wiskel, H. Henein

"A study was conducted to establish the effective heat transfer coefficient for a single molten droplet moving in a gaseous medium. Towards this objective, a series of quench experiments were performed on molten droplets of AA6061 aluminum generated with the Impulse Atomization technique (IAP). IAP is a single fluid atomization process capable of producing powders with a predictable mean particle size and a relatively tight standard deviation under controlled atmospheric conditions. Microstructure analysis of the atomized powder was used to establish the extent of pre-quench solidification. A mathematical model was then employed to correlate the Ranz-Marshall and Whitaker equations with the observed particle cooling behaviour. These equations were found to provide a reasonable estimation of the heat transfer conditions only when the variation in gas thermophysical properties across the boundary layer was accounted for in the model. This model formulation of droplet heat transfer has important implications with regards to active sprays and atomization processing operations IntroductionAn understanding of droplet cooling is important in atomization powder production. It is well understood that dendrite arm spacing is inversely proportional to cooling rate during solidificationl1l. Through modification of the heat transfer conditions during metal atomization, the microstructure of a powder maybe tailored to the end user. However, owing to the complexity of gas flow it is difficult to determine a heat transfer coefficient for a moving droplet. This difficulty is further compounded when complex jets and/or streams and their interactions are considered. To provide a base for these more complicated types of analyzes, two approaches have been employed to calculate the effective heat transfer conditions for a single droplet. In one approach, Megardis [ZJ developed a numerical model to investigate the heat transfer process of a free falling droplet undergoing laminar convective cooling. The effective heat transfer coefficient as a function of angular position was determined by numerically solving the fluid and energy equations for the system."

Jan 1, 1999

By Alexandre Monteiro

Alumina precursor powders can be precipitated from aqueous solutions, using hydrothermal decomposition of urea to deliver base homogeneously to the system. Primary particles agglomerate early in the process, generating a wide size distribution. The presence of a polymeric surfactant such as polyacrylate can suppress or delay agglomeration, reducing particle size and narrowing the size distribution. The stabilization of commercially available a-Alp03 powder with polyacrylate was studied, investigating the effects of polyacrylate molecular weight, ionic strength and temperature. The effect of aluminum concentration, polyacrylate molecular weight and urea concentration on the precipitation of alumina precursors in a sulfate- urea system in the presence of polyacrylate/polyacrylic acid was then studied. The hydrolysis kinetics were followed, and particle sizes were determined. Precipitates were further characterized using energy dispersive spectroscopy. The particle characteristics are discussed in terms of the process conditions.

Jan 1, 1994

By Jean Goldschmidt

Recycling of fine oxidized particles of non-ferrous metals usually cannot be carried out by pyrometallurgical methods. 'Hydrometallurgy provides an alternative technology to reintroduce? the resulting products as secondary raw materials into the industrial cycle, thereby saving resources and energy while keeping the environment a little cleaner. The paper summarizes the methods employed by Hydrometal to achieve these objectives and? stigmatizes the latest counterproductive international regulations which create ever more obstacles to environmentally sound recycling.

Jan 1, 1995

By R. Altman

A Brookfield viscometer fitted with a stainless steel bob was used to measure the viscosity of industrial lead blast furnace slags between 1126 and 1298°c. Slag oxidation state was characterized by first annealing the? slag samples at 750°c in sealed copper tubes in order to precipitate magnetite crystals. The magnetite concentration was then measured on an Outokumpu Saturated Magnetic Analyzer. Using an Arrhenius-type equation, a viscosity model was developed by regression. The equation below accounted for 75% of the variability in the data used to generate the regression coefficients and, on average, could predict viscosity within ± 12% of the measured value. The greatest difficulty encountered in measuring viscosity was due to the occasional presence of solids in the slag which caused, at times, erroneously high viscosity measurements. Precautions to minimize this problem are outlined in the text.

Jan 1, 1985

By C. S. Griffith

Lithium Australia NL (ASX:LIT) and ANSTO Minerals have been working together since 2015 on the development of halide accelerated leaching for the extraction of lithium from lithium-bearing micas, spodumene and clays. This technology has been termed SiLeach® process. The driving force behind development of the SiLeach® process, initially, was to develop a hydrometallurgical process to extract lithium from micas and spodumene without the need for the energy intensive, high temperature processing conventionally applied to lithium extraction. This driving force remains today and continues to hold promise in realising the value of previously under-utilised lithium resources. A comprehensive understanding of the technology and its applicability to the processing of micas and spodumene currently exists, and the flowsheet has been rigorously piloted. Production of battery grade lithium carbonate has been demonstrate

By Stephen Northey, Nawshad Haque, Terry Norgate

"Life cycle assessment (LCA) is a recognized tool to evaluate various processing routes for metal production. Declining ore grades and higher specific energy requirements for primary metal production put greater emphasis on recycling. Greenhouse gas (GHG) emissions of steel and aluminium metal production were quantified with recycling scenarios using material recovery facility (MRF) data from the database of SimaPro LCA software. The GHG footprint of the MRF is relatively minor compared with that of associated transport during collection (i.e. 10 times more than MRF) of curbside recyclable material. Additionally, if the bulk recyclable material is sent overseas (i.e. Australia to China) from the MRF for further processing, the GHG footprint of shipping can significantly be larger compared with the sum of the collection and MRF (assuming electricity is from same source). Thus opportunities exist for reducing GHG emissions from secondary metal production if it is processed close to the MRF.IntroductionIt is a challenge to recycle metals significantly, although theoretically infinite recycling is possible due to their elemental nature. Leaks from the metal stocks in society occur through corrosion, wear and dispersive uses, or via land filling or similar activities that return metals to the earth. In order to provide a technically sound and transparent assessment of metal recycling, a methodology such as life cycle assessment (LCA) should be used. By taking a life cycle perspective, the beneficial recycling properties of metals can be evaluated in a manner that enables appropriate comparisons with other materials or product systems that do not have recycling loops. In practice, mixtures of primary and secondary metals are often used in new products, and also at the end-of-life various processing methods are used for recycling.The difficulty of introducing recycling into LCA is to set the right boundaries for the different flows ending in different product systems. It is a question of which observed material flow belongs to the first product system and which one to the second or subsequent systems. Recycling can be part of any product LCA. However, it is often a complex issue which requires specific considerations. As pointed out by Yellishetty et al. and Birat et al. [l, 2], LCA practitioners are left with much freedom in allocation of environmental burdens to account for recycling, thus making subjective judgments on recycling and allocation of credits to recycling. This often makes it difficult to compare the results of LCA studies conducted by two different practitioners even on the same processes. As LCA is often used to define policy in government, business and society circles, it should be based on a sound, objective and unbiased description of recycling."

Jan 1, 2014

By Vadim J. Jabotinski

Electron beam processing is potentially very attractive for the high temperature treatment of hazardous materials. The very high power efficiency of the electron beam energy source (80- 90% of the power from the electric power line is converted to useable energy) is one of the positive features of this technique. This paper will consider advanced electron beam concepts for solid, liquid, and gaseous waste treatment such as stabilization of radioactive solid and liquid hazardous streams. Fundamental aspects and applications including an analysis of the economic potential of electron beam processing of waste treatment will be presented.

Jan 1, 2000

By Satu Strömberg

Four different nickel concentrates were oxidized in a laboratory scale laminar flow furnace in simulated flash smelting conditions. The major nickel- and iron-bearing minerals in the con- centrates were pentlandite, violarite, gersdorffite, and pyrite and pyrrhotite, respectively. Thermal decomposition, ignition and oxidation behavior of nickel and iron sulfides were examined by using optical and scanning electron microscopy. General reactivity of the concentrates was monitored with sulfur removal which was most effective in violarite-based concentrate. Pentlandite-concentrates needed higher experimental temperatures for complete desulfurization and gersdorffite-based concentrate contained 5 - 10 % of the original sulfur even in the most oxidizing conditions studied (1 100°C, 50 vol-% 02). The reactivity of the iron minerals was found to depend on the other minerals present in the concentrate. In this paper, the observed re- action products and mineralogical changes are presented and preliminary conclusions of possible reaction mechanisms of nickel-bearing minerals are discussed.

Jan 1, 1997

By S. P. Song

A computational methodology based on the coupled finite element and boundary methods is developed to predict the free surface shapes of electrically conducting liquids supported by the electromagnetic field. The work is an extension of our previous FEIBE model for induction calculations. The free surface algorithm is developed using the Weighted Residual Method, the very same used for nonlinear finite element formulation. This allows the treatment of field computation and free surface prediction in the same manner, thus making easier the formulation of the magnetically-supported free surface problems. Like other nonlinear algorithms, the boundary/finite element free surface scheme is also iterative owing to the fact that free surface shapes are unknown a priori. But the numerical scheme is robust and efficient and is capable of handling rather complex free surface deformations. Computational algorithms will be given and are tested by comparing with other solutions whenever available. Computed results of magnetically-supported free surface shapes are presented for magnetic levitation under microgravity and floating zone refining processes under normal gravity.

Jan 1, 1996

By R. G. Hilton

This paper deals with application of Super Detox? stabilization technology to the treatment of electric arc furnace dust (US-EPA listed hazardous waste KO61 ). The process has been used on approximately 170,000 tons of electric arc furnace dust. In addition to the nearly four years of commercial experience at Sterling, Illinois, the process is now being permitted for application at two other locations. The process was originally developed by the Bethlehem Steel Corporation and then further improved by Conversion Systems, Inc. (Bethlehem Steel's Licensee). The treatment process offers many unique bases for its selection, including: A) Low cost compared to the treatment alternatives; B) Lowest available TCLP leachate levels for any process treating K061. Many other processes leave some residue that represents a disposal requirement, although often not addressed; C) Produces minimized final waste disposed, including the fact that the total volume of dust generated and less than the volume occupied by the residue slag from HTMR; and, D) Opportunities for the beneficial utilization of part or all of the waste stream through the development of chemical and physical characteristics. Each of these aspects will be specifically discussed in the paper, including that status of the operations now under permit.

Jan 1, 1994

By Chen L. Lin

Scientific visualization is an ideal methodology for investigating complex phenomena that are characterized by large amounts of data. Furthermore, it is invaluable in the study of processes that evolve in time. Scientific visualization relies heavily on computer graphics, image processing and video technologies. Specific applications of scientific visualization in the minerals and materials processing fields that are considered in this paper include: 1) applied CT technology for multiphase materials and minerals, 2) time averaged density profla in air- sparged hydrocyclone (ASH) flotation and 3) dynamic motion analysis of ball mill grinding.

Jan 1, 1993

By J. Rastas

The recovery of lead, silver and gold from existing and potential zinc process residues using a sulfidization-flotation method was investigated on a laboratory scale. The following residues were tested: neutral leach residue, high acid leach residue, and hematite residues. The sulfidization of lead and silver is carried out at low pH by the addition of a stoichiometric amount of sulfide at a controlled rate. To increase the particle size of the sulfides, seeding with synthetic lead and silver sulfides -is employed. The flotation is carried out at pH 2-4 using low pH-collectors such as dithiophosphates and dithiophosphinates. Special attention must be paid to the role of oxygen in the conditioning stage. The effect of different parameters on both the sulfidization and the flotation has been evaluated. Recoveries of 85-90, 90-95 and about 80 % were obtained for lead, silver and gold, respectively. Typically, concentrates containing 50-60 % lead, 3-5 kg/t silver and 10-15 git gold were produced.

Jan 1, 1990

By Xiancong Zhao, Hao Bai, Qi Shi, Zhancheng Guo

Reducing electricity cost is important for energy intensive industries such as the iron and steel industry. With the implementation of time-of-use (TOU) electricity price, plenty of attention has been paid to the optimal management of byproduct gases. The time-of-use (TOU) electricity price is the practice of implementing different prices for different times of use. It is possible to reduce electricity cost by adjusting the amount of product gases stored or used for power generation throughout the day. In this paper, a novel mixed integer linear programming (MILP) model concerning the TOU electricity price is proposed to optimize byproduct gas use. Compared with previous models, this model considers the optimal load shift between gasholders and boilers under TOU electricity price. The case study of a steel plant demonstrates that the electricity purchase cost can be reduced by more than 30% after optimization.

Jan 1, 2016

By Zhucheng Huang, Lingyun Yi, Bin Chai, Tao Jiang

"A high iron content manganese ore was reduced at 900~1200°C and followed by a magnetic separation process. SEM and EDS analyzes were employed to examine the transformation of microstructure and phase in reduced sample and the mechanism was revealed. Results showed that elements enriched during reduction. Iron existed in the metal iron phase and most of oxygen formed compound with manganese. Consequently a clear distinguish between iron phase and manganese minerals formed, which was beneficial to the separation of iron and manganese. But the iron phase can not be monomer dissociation in grinding process and manganese compounds turned into magnetic product as package and mechanic inclusion due to the isomorphism of iron and manganese and the small particle size. And MnO could be found partially in iron phase, which hindered the further separation of manganese and iron.IntroductionManganese is widely used in industry. The amount of manganese used in steel industry is very huge and 90% manganese is used in steel industry. Manganese ore resources are rich in China, yet with fewer rich ore but more low-grade ore which accounts for 93.6% and fine refractory ore. The constitution of the ore is very complex and more than 73% of all the manganese ore contains iron[l,2]. With the increasing of consumption of steel, the demand for manganese is becoming larger and larger and the imported ore accounts for more than 50%. Therefore, how to use the manganese ore efficiently has very significant meaning. The main method is manganese residual, which is simple and stable. However, the development of the method is limited by the quality of manganese ore, the huge amount of manganese residual, the technology of blast furnace process and economics[3,4]. Chemical benefication which may pollute environment and is difficult to recover iron is still being researched[5,6]. The paper investigated the process in which anthracite coal was the reducing agent for coal-based direct reduction and magnetic separation of the ore, and SEM with EDS measurements were employed to examine the transformation of phase in reduced sample and the mechanism was revealed[7,8]."

Jan 1, 2013

By E. Anelli

Based on experimental continuous cooling transformation (CCT) diagrams, an artificial neural network has been trained to predict the amount of microsturctural constituents and hardness resulting from and controlled cooling at rates from 150 to 0.015 K/s. It can be applied to quenching and normalizing processes of low-alloy steels with 0.05-0.30 C% and 0.4-2.0% Mn -with possible microalloying additions. Examples of the good predictive capabilities about 15 Vickers standard deviation for hardness and a few percent for volume fraction of phases) are reported' Keywords: Austenite decomposition, low. And medium-carbon steels, artificial neural networks

Jan 1, 2003