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By C. M. F. Viera

In this work the properties of a clayey ceramic incorporated, up to 10 wt.%, with three types of wastes from a water treatment plant was evaluated. To determine the physical and mechanical properties such as linear shrinkage, water absorption and diametrical compression, specimens were prepared by 18 MPa uniaxial pressure and then fired in laboratory furnace at 700oC. The results indicated that the wastes incorporation changed the properties of the clayey ceramic. From the results it was found it possible to recycle these wastes into clayey ceramic in low amounts to avoid deleterious effect on the quality of the fired product.

Jan 1, 2008

By F. Mucciardi

While flash smelting and converting are capturing a greater share of the market, injection through circular injectors will remain with us for the foreseeable future. The use of top lances for injection is a key feature in several processes (e.g. Mitsubishi, Ausmelt). Tuyeres, on the other hand, are incorporated into a number of processes (e.g. Noranda, Peirce-Smith). To date no lances or tuyeres are cooled by an external source. The reagent provides the bulk of the cooling. With limited cooling, it is normal to have substantial wear on the nozzles - especially in the case of lances. To overcome the issue of wear, a new patented injector (lance or tuyere) has been developed by Noranda and McGill University. This novel unit is based on heat pipe technology. It can operate for an extended period of time without wearing. Enhanced lance/tuyere life is achieved by operating the injector at a low enough temperature that promotes the formation of a thin frozen layer on the outer body of the unit. The vaporizing and condensing substance within the unit acts to cool' the high heat flux portions and dissipate the heat to areas of low heat flux outside the vessel. A fairly large number of tests have been conducted with a prototype unit. The tests have shown that the heat pipe lance is a viable unit. In this paper is detailed a test which illustrates how the lance functions when pure oxygen is injected into copper matte. In addition, the findings from a basic study of a heat pipe in high heat flux environments are also presented.

Jan 1, 1999

By Ann M. Hagni

Electric arc furnace (EAF) dust from the secondary steel industry contains lead, cadmium, and chromium that causes it to be classified as a hazardous waste. Pyrometallurgical treatment of EAF dust is directed at recovering zinc and simultaneously rendering the dust non-hazardous. The mineralogy of the EAF dust is important in determining the occurrence and phase relationships of the zinc, lead, cadmium, and chromium contents. The principle phases in EAF dust as determined by reflected light microscopy, SEM-EDS, and XRD are solid solutions of the iron spinels (franklinite, magnetite, and jacobsite), zincite, hematite, and Ca-Fe-Si glass. Chromium is present in small amounts in solid solution in the spinels. Cyclone sizing of the minus 53 pm particles shows that more than 50% of this size fraction are less than 10 pm in diameter. The <I0 pm particles contain zinc as both franklinite in solid solution with magnetite and jacobsite, and zincite as determined by transmission electron microscopy and XRD. Auger electron spectroscopy did not detect coatings of volatile phases on the surfaces of EAF dust particles.

Jan 1, 1994

By Manabu lshimaru

Solid-liquid interfaces as well as defect formation processes during crystallization of melted silicon (Si) have been examined by using molecular-dynamics (MD) simulations. The ordinary Langevin equation employing the Tersoff interatomic potential was used for the calculation of the atomic trajectories. A solid-melt interface has a tendency to form {]] I} microfacets during the crystal growth in the [001] direction, while it is essentially flat during the (Ill) crystallization. Because of the difference of the interfacial structures, the structures of grown-in defects and defect evolution depend strongly on the growth direction. We discuss defect structures and their formation processes within the context of our results as well as previous experimental observations.

Jan 1, 2001

By K. Morsi

Titanium-titanium boride whisker (TiBw) composites are emerging as strong candidate materials for advanced applications within the automotive, aerospace and defense industries. Although increasing TiBw volume fraction improves the specific stiffness and wear resistance of titanium, it is usually on the expense of fracture toughness and ductility especially at increased volume fractions of reinforcements where whiskers interlock. This research addresses strategies for microstructural design that may overcome these shortcomings, by generating titanium composites that are locally reinforced with TiBw through in-situ reaction in segregated regions of the microstructure and separated by ductile Ti matrix. The effect of varying composite reinforcement particle sizes (i.e. size of the reinforced regions) on the pressure-less sintering of these dual matrix composites is discussed. Electric current activation was also used to generate high density dual matrix composites and a new simultaneous imaging and modulus mapping technique was used to characterize these unique microstructures.

Jan 1, 2008

By Leonel Contreras

The gas treatment system, MALIGAS (in Spanish MAnejo y Llmpieza de GASes which means handling and cleaning of gas), is part of the Codelco-Chile Potrerillos Smelter decontamination plan; which includes the newly designed system for the cooling and cleaning of the gas generated from a Teniente Converter and four Peirce Smith Converters. The gas generated in the process is captured by water cooled hoods and mixed with air. Then the gas enters a cooling pre-chamber which utilizes a water cooled screen to capture and remove the coarse and semi-fused particles. At this stage; the gas loses a portion of its heat with temperature falling below 608°C which is a necessary condition to avoid damage to the pipes, ducts and other metallic structure of the gas handling system. The gas is further cooled at the Radiation Cooler to a temperature ranging between 315 and 380°C. The gas is conditioned to avoid damage to the electrostatic precipitators that are designed to clean the gas by removing significant amount of dusts from the: gas stream. This gas stream is currently discharged to the stack, however, it will be treated in a sulfuric acid plant that is currently under construction and is scheduled for commissioning during the second half of 1999. The gas handing and cleaning system has been operated without any significant interruptions. Minimal emissions of SO2 and dusts in the work place are noted. The system requires minimum maintenance. The key to the high availability of the system is due to the good, performance of he Radiation Cooler, which efficiently cools the gas before entering the electrostatic precipitators (ESPs). This enables the ESPs to remove the dusts efficiently.

Jan 1, 1999

By W. G. Davenport

Chapter 4 examined Inco (oxygen) flash smelting of pure chalcopyrite concentrate. It showed that the oxygen and flux requirements for auto thermal smelting are readily determined by a matrix calculation. This chapter extends this matrix approach by applying it to a multi-mineral concentrate.

Jan 1, 2001

By Thomas Brynjulfsen, Merete Tangstad, Eli Ringdalen

Manganese ore fines cannot be added to the submerged arc furnace directly as they will prevent even gas flow through the burden. Low gas permeability in the burden will lower the degree of pre-reduction of ore subsequently increase the carbon and energy consumption of the process. In order to utilize manganese ore fines in the furnace, they are typically agglomerated into sinter. In this work, the melting and reduction properties of Gabonese sinter and Gabonese ore have been investigated in pilot scale experiments. Two experiments were conducted, one with 100% sinter as manganese source and one with 50/50 sinter and ore. Lime was used to achieve a charge basicity of 0.72 in both experiments. The composition of slag samples from the excavation of the furnace was established using EPMA(WDS), and the composition of the tapped slag and metal was found using XRF. It was found that while the coke-bed size would determine the tapped slag composition, the melting behavior of the Mn source would determine the mixing with lime.

Jan 1, 2014

By Markus A. Reuter, Antoinette van Schaik

"Product design engineers select from a wide range of materials and combine them into multimaterial product designs. These include various materials (metals and non-metals) which are complexly integrated (e.g. welded, glued, alloyed, layered). The recycling/recovery rate of consumer products are determined by the different materials and alloys used, but also by the particle size and multi-material particle composition after shredding (combination of materials due to design). Eco-design (for recycling) and Design for Recycling (DfR) can only be conducted if the interconnectivity of material/metal in various unliberated materials is accounted for and its effect on material and energy recovery can be linked back to design. This paper will discuss the basic principles of these DfR models and it is shown how these tools (i) are linked Computer Aided Design (CAD) and Life Cycle Assessment (LCA) software, (ii) affect conceptual design specifications of products, (iii) integrate the complex detail of the recycling system and recyclate quality and hence (iv) make recycling an integrated part of the product system. Furthermore, it is shown how these assessment tools and models can be applied for benchmarking of the recyclability and environmental damage created by the recycling of end-oflife consumer goods in order to e.g. (i) provide the (original) equipment manufacturer with knowledge and solutions to support product stewardship and Extended Producer Responsibility; (ii) create awareness of the consequences/benefits of design, products and recycling systems to manufacturer, designer, legislator, recycler etc.; and (iii) assist the consumer in their choice of consumer goods from an end-of-life point of view.IntroductionA first-principles basis is required in order to be able to simulate and predict the recycling/recovery behaviour of products facilitating Design for Recycling (DfR) and Eco- Design. This links recycling technology and the environmental consequences of recycling directly to product design."

Jan 1, 2008

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 S. N. Lekakh

Experimental work and thermodynamic simulations of cast iron refining were carried out using various additions of alkali and rare earth metals. The refining reactions for sulfur and oxygen removal were studied for melts treated with Mg, Ca, and Ce. The measured data and the results of the computer simulations were in agreement. Experimental kinetic data, together with the thermodynamic calculations, were used for optimization of the amount and sequence of the addition of nodulizers for ductile iron production.

Jan 1, 2009

By E. Gutierrez-Miravete

Hot pressing processes are widely used to shape metallic, ceramic, and glass components. The process is an essential step in manufacturing ceramic fibre-glass matrix composites. The paper describes the use of computer simulation by the particle method, to the analysis of the deformation and flow of glass during hot pressing. The hot glass is represented by an assembly of interacting particles which deform in response to the applied pressure. The results, which should be regarded as complementary to continuum-based studies, provide useful insight about the hot pressing process.

Jan 1, 1990

The generation of acid mine water is? due to the oxidation and weathering of sulfide bearing tailings and overburdens. Ferrite precipitation prooess has been applied to treat acid mine water. The conventional ferrite preC1pitatlon requires air oxidation at high temperature, or long aging time or addition of magnetite powder ,as promoter. In this investigation, a modified ferrite, precipitation process is developed by which magnetic ferrite can be produced at an ambient temperature. Acid mine waters from Berkeley Pit (Montana, U. S. A.) and from Noranda Tailings (Quebec, Canada) were used. The co precipitation of heavy metals from these two acid mine waters is studied as a function of FeIM molar ratio, oxidation time and settling rate under applied magnetic field. The investigation indicates that the modified ferrite co precipitation can remove substantially all of the, dissolved metal ions from acid mine water. The ferrite product obtained after precipitation&apos; is characterized by XRD, SEM, BET and saturation magnetization. The results show that spinel ferrite, precipitation can be achieved at room temperature and the saturation magnetization of ferrite product from,acid mine water is comparable to that of pure ferrites.

Jan 1, 1995

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 S. Castro, P. Alfaro, C. Moctezuma

IMMSA operates a conventional roasting-leaching-purification-electrolysis plant for the production of zinc from concentrates in San Luis Potosi, Mexico. The leaching circuit was designed to take into consideration a feed mixture to the roaster with a maximum iron content of 7%. Since the start-up of the plant in 1982, the zinc recovery increased to 94.5%. However, an increase in the iron content in 1997 caused an important decrease in the global zinc recovery. Two new steps were added to the leaching circuit and modifications were made to the other steps in order to increase zinc extraction. Two new automated press filters were installed to replace the original vacuum drum filters and to minimize soluble zinc losses. Additionally, the residue treatment steps in purification were modified and a calcium removal circuit is just starting operation. These actions, besides improving the operations, have as the main objective to increase the global zinc recovery to levels above 94.5%.

Jan 1, 2000

By R. W. Smith

A microorganism will function as a mineral flocculant if it is to some degree hydrophobic and can attach itself in some manner, such as through electrostatic interaction, to the fine mineral particles to be flocculated. The present paper concerns the use of a hydrophobic bacterium, Mycobacterium phlei, as flocculating agent for phosphate slimes. Experimental work on the flocculation of phosphate slimes and of dolomite and clay mineral suspensions was performed. It was found that M. phlei functions as an excellent flocculant for a dolomitic slime but does not function as well for mineral suspensions where large quantities of the solids are finer in size than the approximately 1 µm size of the bacterium.

Jan 1, 1992

By Cody Burcher-Jones

The recovery of rare earth elements (REEs) through heap leach/in situ techniques from so-called ion adsorption clays (IACs) is attractive due to their inherent simplicity. However, the underlying mechanisms of these processes are poorly understood. In this study, the deportment of REEs in a typical IAC material has been investigated and was found to concentrate in the phyllo-layers of the clays, especially hallyosite, and was readily desorbed by various ion-exchange reagents indicating various potential routes to liberate them. Here we are reporting the use of seawater (0.5 M NaCl), spiked with various amounts of (NH4)2SO4, and found better extraction using a reagent mixture than NaCl on its own. Further, the leaching of REEs from a bed of clay material was investigated over time to understand the rate of transport through the stagnant material. Results indicate that REE release is likely to be controlled by diffusion through the clay material, while desorption in agitated systems is rapid. A degree of fractionation between different REEs can be observed during diffusion. Nonetheless, the successful operation of in situ leach operations for this type of material would depend primarily on how easily solution cocktails can be made to flow through the bed material.

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 K. Olsen

As aluminum alloy usage in automobiles grows, there are increasing demands on recycling processes and facilities to deal with mixed alloy automotive aluminum scrap. These processes and facilities strive to produce near virgin aluminum stock, which can be relatively costly and difficult. One alternative is to use physical processing methods to upgrade the scrap properties instead of chemically refining the scrap. The Impulse Atomization Process (LAP, patent pending) is a new process for making metallic and ceramic powders. It can produce fine homogeneous microstructures in scrap aluminum alloys due to high undercooling and rapid solidification. The particles have a very narrow size distribution and are in a convenient form for consolidation. This paper compares and contrasts the microstructural features of Impulse Atomized. and quenched Impulse Atomized powders,&apos; for both AL6061 and a scrap aluminum alloy composition.

Jan 1, 1995

By Kang Wan, Lei Tang, Jianchao Li, Jieyu Zhang, Minqi Sheng, Jifang Xu

"The viscous flow phenomenon in slag close to the liquidus temperature was considered. A simple approach that liquidus temperatures of melt could be derived from viscosity data was employed. The potential of this method for estimating the liquidus temperatures of pure water and binary alloy was demonstrated. The liquidus temperatures of the CaO-Alz03 based slags obtained from the second derivative method depends upon the number of viscosity values available at different temperature intervals. The results indicated that plots start deviating from the straight-line behavior at temperature as expect, and the second derivatives show the break points at a certain temperature, which is the liquidus temperature. Comparisons among the present observations as well as the characteristic temperature of the selected slags, which measured by the hemisphere method and DSC, indicated that it is possible to get a reasonable idea of estimate the liquidus temperatures from activation energies for viscous flow.IntroductionThe liquidus temperature of slag, which has a significant effect on the kinetics of chemical reactions and the slag-metal separation, is extremely important for metallurgical operations. Experimental measurements of the liquidus temperatures of slags are difficult, since slags invariable supercool. In addition, behavior of a single constituent in a multi-component slag is different in different circumstances due to its interaction with other constituents. Hence, it is essential to study the liquidus temperature of each particular slag resulting from a special process. Usually, the compositions of the slags aimed to the single liquid region of the phase diagram. However, the phase diagram of many slag systems, which back often to the 1950's, involves considerable uncertainties. Many liquidus temperatures are given as dotted lines in Slag Atlas [1]. Disagreements between the phase diagram and the reality have been found [2]."

Jan 1, 2013