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By Richard D. Hagni

Reflected light microscopy is routinely applied to the study of ore minerals and textures in polished sections prepared from a wide variety of ore specimens. With the increasing interest in environmental problems, the important role of the reflected light microscope in the precise phase identifications and the determination of the textural relationships between those phases needs to be recognized. Among other environmental applications, the microscope has been applied to the recognition of lead smelter particles from remote collect sites in Missouri and those particles have been compared to dust particles from specific localities at the nearby lead sinter plant and lead blast furnace. Dust from a secondary copper refinery has been studied for its mineralogy. Soils in the vicinity of a Missouri lead smelter have been studied for their mineralogy in preparation to the clean up of those soils. Electric arc furnace (EAF) dusts, recently classified as hazardous waste by the EPA, have been examined for their mineralogy and textural intergrowth in order to better evaluate proposed metallurgical treatment procedures to render the dust non-hazardous. The initial products from experimental metallurgical treatment of EAF dusts also have been studied to aid in determining the effectiveness of those treatment procedures. Refractory gold sulfides that have been roasted in the presence of lime to retain environmental objectionable sulfur and arsenic while recovering the gold have been studied by RLM to determine their mineralogy, porosity, and permeability for cyanide leach solutions. These case histories illustrate the applicability of ore microscopy to the study of problems related to environmental concerns.

Jan 1, 1995

By Yuri Bychkov

The Electron Beam Melting is the most efficient technology for metals and alloys refining. For ,secondary metals processing the Electron Beam Skull Melting (EBSM) with the electromagnetic stirnng (EMS) of melt in the crucible was shown to be the most appropriate. The copper produced by EBSM with EMS possesses higher density and electric conductivity in comparison with other refining methods. The details for high power electrical machines were cast of the copper waste refined by EBSM technology.

Jan 1, 1995

By Manuel Zamalloa

The outstanding metallurgical performance of the Noranda continuous converter (NCv) in operation since November 1997 has allowed the company to meet production and environmental targets. This achievement positions this new technology as a strong alternative continuous converting technology for copper production. Knowledge of slag chemistry has been important in this respect. The purpose of this paper is to discuss the effect of key parameters including temperature, oxygen potential, slag composition and levels of copper oxide in slag on the conditions leading to magnetite precipitation, as well as on the conditions affecting the liquidus ranges of NCv slag. The above variables are evaluated using industrial data and thermodynamic predictions. Practical implications of customizing operational fluxing procedures to determine optimum operating windows are also discussed.

Jan 1, 1999

By L. Sh. Tsemekhman

A new technology for the treatment of copper nickel-containing concentrate after high-grade matte flotation to blister copper with the production of liquid silicate slags in a vertical autogenous unit with upper oxygen blow has been considered. The copper and nickel behavior in the process of sulphide copper concentrate interaction with silicate melt containing oxide copper has been studied. The general mechanisms of such interaction are found.

Jan 1, 2003

By Chen Dong, Yuanling Gao, Jilai Xue, Jun Zhu, Luxing Feng

"Porous Ni-Ti alloy has many applications in a wide range of engineering areas. The porous NiTi alloys were prepared from Ti and Ni powders in sintering process under argon atmosphere. The major chemical compositions of the sintered Ni-Ti body were Ni Ti, Nh Ti4O and Nh Ti, respectively, the internal pore structures were characterized by image analysis technique, which were dependent on various processing parameters such as sintering temperature, amount of poreforming agent, forming pressure, etc. The results show that the porous alloy samples had the characteristics of uniform pore and high open porosity; pore-forming agent and sintering temperature are important factors in porous; pressure affected the sintered products' pore, by affecting the combination of alloy powder with pore-forming agent.IntroductionPorous Ni-Ti alloy materials exhibit not only excellent shape-memory and superelasticity, high yield strength and ductility, good corrosion resistance and biocompatibility, but also have low density, low stiffness, and high energy absorption rate due to their porous structures [1]. In recent years, these porous Ni-Ti alloys have found applications in a wide range of engineering areas, such as bone implants [2-4], impedance-matching connectors [5], energy-absorbing structures [6,7], separators [8] and actuators [9], etc.Pore characteristics can play very important role in determining of the performance of porous NiTi alloys. For example, when the alloys are used to repair or replace hard tissue implant material, the pore shape and size not only determine their mechanical properties, but also have great effect on the fluid transmission of human body. The pore characteristics can also influence the stressstrain behavior of the porous Ni-Ti alloy and, thus, strongly affect their mechanical properties, superelasticity, and fracture mechanisms [10].In this study, the Ni-Ti alloys with high porosity were prepared in a powder sintering process under argon gas. The pore characteristics were investigated using SEM, XRD and image analysis techniques, especially in association with the content of pore-forming agent, sintering temperature and compacting pressure."

Jan 1, 2011

By Duclerc Fernandes Parra, Luis Filipe Carvalho Pedroso de Lima, Washington Luiz Oliani, Danilo Marin Fermino, Ademar Benevolo Lugao

The modified polypropylene was obtained from isotactic polypropylene (iPP) in spheres by irradiation with gamma rays in the presence of acetylene. A new morphology with distinct rheology is obtained by this process in which occurs: degradation, branching and/or crosslinking. The objective of this study was to investigate the effects of thermal aging on the crystallinity and morphology of the modified polypropylene, High Melt Strength Polypropylene (HMS-PP). The thermal stability was evaluated after aging of samples using a stove at temperature of 90 °C, in presence of air at different periods of time. Aging effects were characterized by: Thermogravimetry analysis (TG), Differential scanning calorimetry (DSC), Infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). In thermooxidative conditions, the formation of oxidation products essentially involves a hydrogen abstraction by the peroxyl radical, leading to hydroperoxides as primary products and chemical degradation in the immediate crack tips. The effect of thermal degradation (chain scission and oxygen diffusion) on iPP was a more intense crack formation. Surface cracks increased with the aging time. In comparison of iPP, the modified PP samples had a morphological barrier inhibiting the penetration of oxygen into the sample and in consequence limit the propagation of degradation

Jan 1, 2015

By Takashi Nakamura, Kenji Oosumi, Kazuhisa Fujisawa, Takayuki Kogishi

"Recycling of used aluminum beverage cans(UBCs) is one of the important issues for aluminum manufacturer presently. The direct re-melting of UBCs shows two problems. One is a reduction in molten aluminum recovery and the other is a contamination of other metals such as Ti and Fe from paints. Both problems are caused by paints coated on the surfaces of aluminum cans. Removal technique of the paints, therefore, has been required. Although roasting and shot blast techniques have been developed, both were not successful in removing the paints effectively. A swell-peeling method has been applied to remove them using a methylene chloride solution with acids and it works very well. Small laboratory scale tests have been carried out to develop the commercial process and clarify the mechanism of the swell-peeling method in the present study.When the surface area of UBC is more than 10 cm2, peeling time is independent of the surface area, about 60 seconds, because swelling phenomenon is controlled by the penetration of the liquid through the fine pits on the surface of the paint. This is good for a commercial process. Peeling takes place when the swelling force generated by methylene chloride exceeds the adhesion force between the film and the surface of aluminum, that is weakened by the coexisting acid, especially halogenated acetic acid."

Jan 1, 2000

By P. V. Ananthapadmanabhan

Feedstock powders of metals, alloys and ceramics for thermal spray applications have to meet several specifications. Particle shape, size and distribution, powder flow characteristics and density are the important factors that need to be controlled, in order to ensure high spray efficiency and better coating properties. Thermal plasma technology can be effectively utilized to produce metal, alloy and ceramic powders for spray applications. The present paper describes plasma spheroidisation of commercially available aluminium powder and nickel-aluminium powder blend in a plasma reactor. Results show that the processed powder particles bear spherical morphology with excellent flow characteristics, which make them ideal for thermal spray applications.

Jan 1, 1997

By Keizo Uematsu, Kumiko Sanda, Nozomu Uchida

"Full understanding of mechanical properties is the most important assignment in ceramics. Establishment of defects-property relationship is crucial for fulfilling the assignment. This study reports detailed characteristics of defects and their relevance to the mechanical properties for alumina ceramics made through a typical industrial processing. Novel characterization methods were applied to evaluate their defects. A very simple direct correlation was successfully found between defects and properties in ceramics. This result is a great epoch in the field of ceramics. IntroductionThe ceramic materials are used in refractoriness, corrosion resistant materials and structural materials. The low fracture toughness and scatter of strength are very important problems in ceramics. The toughness of ceramics is lower than metal and polymer materials, and the allowed defect size is small. Very small internal defects (pore, crack, huge particle) can be a fracture origin in the brittle fracture. The characteristics of defects such as size, distribution and shape change markedly by process condition, which cause the scatter of strength. This study conducts quantitative evaluation and direct observation of the sizes, shape and a number of internal defects with a light microscope, and discusses the relationship for mechanical properties and defect sizes"

Jan 1, 2000

By Jiangwei Shen, Cong Wang, Haibin Zuo

The research on the formation of Silico-Ferrite of Calcium and Aluminium (SFCA) in the process of cooling and solidification is rarely reported. The crystallization process was observed by using scanning electron microscopy (SEM) and optical microscope in this paper. The effect of different cooling system on the microstructure and phase composition of the sinters was investigated to obtain the appropriate cooling rate to improve the metallurgical properties of sinters. The experimental results show that the crystallization of calcium ferrite is getting better when the cooling rate is decreased from water quenching to cooling in the air. There are a large number of hematite phases with interconnected crystal structure in the sample cooled in the air. In the case of the compressive strength, it was determined by the mineral composition and pore structure, higher SFCA and hematite contents in sinter cooling in the air lead to a higher strength. Glass phase in the water quenching sinter was the major reason for the lowest strength. High porosity contributes to a decrease in compressive strength for the sinter cooling in the furnace. Therefore the air cooling was the appropriate cooling rate to achieve high quality sinter under this experimental condition.

Jan 1, 2016

By W. Song, C. Richards, B. Q. Li

"This paper presents a two-phase flow numerical model for spouting gas-particle flow reactors used in chemical vapor deposition processes for manufacturing heart valves and other biomedical implants. The model is developed based on the Eulerian-Eulerian formulation of gas-particle flows, with the k-e engineering model modified with the presence of particles for the description of turbulent gas flows. In parallel with the numerical model development, physical models are set up, where the particle image velocimetry is used for visualizing the particle flows and spout shapes and heights and optical probes are used to measure the particle velocities. The numerical model predictions are compared reasonably well with the experimental measurements.IntroductionVarious biomedical implant components, such as bone joints, dental components and heart valves, are coated with bio-compatible thin films by chemical vapor deposition in particle-laden chemical reactors [l-5]. In these reactors fine particles are used as packing and supporting media. During the coating operation, these packed particles are fluidized by an upward gas jet from the nozzle, reach a certain height and fall back on the top of an annulus region. These recirculating particles are mainly for levitating the implant components (usually one or two in a reactor at one time) so that every portion of them is equally exposed to the gaseous atmosphere. An equal exposure is critical for forming a uniform, mechanically strong and corrosion-resistant coating on implants. Plant experience shows that the quality of the coating is directly related to a stream of operating parameters such as temperature, particle size and loading, and gas flow rates [6]. Optimization of these operating parameters for improved reactor performance depends crucially upon our fundamental understanding of the physics governing the gas-particle flow, heat, and mass transfer phenomena taking place in these reactors."

Jan 1, 2004

By C. M. F. Vieira

The main characteristics and physical and mechanical properties of clays from the county of Campos dos Goytacazes, located at the northern part of the State of Rio de Janeiro, Brazil, are presented. The characterization included mineralogical composition, chemical composition and particle size distribution. The properties related to water absorption, linear shrinkage and flexural rupture strength were obtained in samples that were prepared by 20 MPa uniaxial pressing and fired at 950 and 1100oC. The results showed that the clays are predominantly kaolinitic with high percentage of clay minerals. The kaolinitic structure associated with a small amount of fluxes confers a refractory behavior which makes difficult the sinterization and impairs the ceramic consolidation.

Jan 1, 2009

By Qin Hua, Xiangru Chen, Qijie Zhai, Yongsheng Yan, Liang Chang

"In this paper, pure bainite ductile iron and their alloying form of 0.2wt% niobium were prepared by a controlled cooling heat-treatment. The effect of niobium alloying on the microstructure, hardness and impact toughness of bainite ductile iron was studied. The results show that adding niobium effectively improves the hardness and toughness of bainite ductile iron. The hardness and the impact toughness of niobium-alloyed bainite ductile iron were investigated by varying the temperature at which samples were fed to the incubator.IntroductionThere are two essential methods to prepare the bainite ductile iron: isothermal quenching [I-31, and alloying [4• 51• Isothermal quenching process is very time and energy consumable, concerned as a high cost technique for mass production. Besides, there are certain limitations on the size and shape of castings in this process. In addition, it potentially harms the environment. As for the alloying, Ni, Mo, and Cu have to be utilized to obtain bainite. However, the large demand and high cost of Ni makes it not feasible in practice.It is well known that niobium can promote the formation of carbon compound, and improves the stability ofundercooled austenite, which is preferred to the increase of the hardenability. Previous studies showed that niobium could refine the grain and improve the mechanical properties of gray cast iron [6-81 • Therefore, in the present work, the effects of niobium and the temperature at which samples were fed to the incubator on the microstructures and properties of niobium alloyed bainite ductile iron were investigated."

Jan 1, 2014

By Mitsuhiro Ito

"To allow various wastes containing high levels of chlorine to be used as alternative raw materials for Portland cement, two practical methods of chlorine removal were developed. In the first method, chlorine is extracted from the wastes during the cement manufacturing process. In the second, ash-dust waste with high chlorine content is first washed and then dehydrated to cake before being introduced to the cement manufacturing process. This cake can be used as an alternative for some cement raw materials. By combining the two methods, various wastes previously considered unsuitable for recycling due to their chlorine content can often now be used in cement manufacturing plants. As such, these methods represent a major contribution to environmental protection as well as a solution to problems relating to the diffusion of heavy metals and dioxins from cement plants.1. IntroductionWaste generation levels have risen rapidly in recent years. in both the consumer and industrial sectors and today, the need for effective, efficient waste management is one of the most pressing and serious problem of today's society.The Japanese cement industry has reacted to the increase in waste generation by using certain materials as alternative raw inputs or fuels for cement production, in an effort to contribute to society and conserve energy resources.These wastes often contain non-negligible levels of chlorine and heavy metals, however, both of which are unsuitable for cement production. Depending on the element content, Heavy metals have a particularly negative effect -on cement quality; in addition, they can be released into the environment. Chlorine, on the other hand, is contained in large amounts in incinerated ash from household wastes as well as in certain plastics. Both substances are considered impediments in cement-production, not only because they reduce the quality of the cement produced but also because they impair operating safety on cement production lines.To address this problem, two practical technologies have been established for separation and recovery of chlorine components during cement pre-processing and production. This paper introduces the application of these technologies with a special focus on incinerated ash from urban wastes, a representative form of waste material having notably high concentrations of chlorine, heavy metals, and dioxins. We also outline the technologies enabling this material to be used as an alternative input to cement production."

Jan 1, 2000

By A. Alvarez

In this work, mesophilic and thermophilic cultures have been used in the presence of silver as a catalyst. Chalcopyrite and byproducts of bioleaching were characterized in order to: a) obtain information about the kinetics control of the process, and b) explain the different behaviour observed during the mineral attack. With thermophilic microorganisms (68°C and Norris medium as nutrient) the reaction stopped at approximately 65% copper extraction, with and without Ag ion addition as a catalyst. The remaining chalcopyrite appears surrounded by hydronium jarosite (with ammonium ion in substitution in the "alkaline site"), goethite and elemental sulphur. With mesophilic cultures (35°C and 9K medium as nutrient) the reaction stopped at approximately 25% copper extraction (without Ag) and approximately. 85% extraction (with Ag). In both cases, the remaining chalcopyrite was surrounded by agglomerates of ammonium jarosite (with hydronium ion substitution in the "alkaline site") and some iron oxides and/or hydroxides.

Jan 1, 1999

By Leiv Kolbeinsen, Vincent Canaguier, Ingeborg-Helene Svenum

The syntheses of stoichiometric iron chromite and chromites with chosen impurity content have been developed using the induction skull melting technique. The aim for this synthetic material is to obtain pure samples to study the carburization by methane-hydrogen gas mixtures. For each synthesis, the parameters influencing the skull melting experiment have been considered. The product phases have been analyzed using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS). The synthetic material was subsequently pelletized and sintered in argon. The use of excess iron was found to improve the quality of the final product as well as to help the melting. The difference in magnesium content between first and last solids formed seem to indicate a segregation phenomenon, while no evidence could support a similar trend for aluminum substitution in chromite.

Mar 1, 2017

By Shaik Jeelani, Mahesh Hosur, Esperidiana A. B. Moura, Rejane D. Campos, Emilia S. M. Seo, Kerry Kirwan, Francisco R. V. Díaz, Maria Sotenko

The use of natural fibers with polymeric resins has spread rapidly. In order to improve the mechanical properties of material, in this work, two variables were used: mercerization and electron beam irradiation. This paper describes the preparation and characterization of biocomposites that were prepared in two different routes using green high density polyethylene (HDPE) and Brazil nut pod fiber (BNPF): the first was to irradiate the composite with 150 kGy and the second was to irradiate the matrix with 15 kGy followed by composite preparation. In both cases mercerized and non-mercerized fibers were used. The irradiation process was carried out using a 1.5 MeV electron beam accelerator, at room temperature and in the presence of air. The material was characterized to evaluate the effect of treatment on mechanical properties of material.

Jan 1, 2015

By Ann M. Hagni

"Ceramic matrix composites are inorganic materials that are particularly resistant to heat and abrasion. A magnesia (MgO) and aluminum nitride (AlN) based composite is formed by exposing a magnesia preform to a metallic alloy block in a nitrogen atmosphere at 950°C. The metallic alloy, which is composed primarily of aluminum, is wicked into the preform. Aluminum nitride matrix is grown between MgO particles as the wicked metallic aluminum reacts with nitrogen. Unused metallic alloy, remnant metallic alloy (carcass), and composite produced after 8 hours, 50 hours, and 225 hours of processing are characterized mineralogically. Reflected light microscopy, transmitted light microscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction techniques reveal that in addition to anhedral to euhedral AhNi, AbSbSr, and Al crystallizing in the metallic alloy carcass, AIN and (Al,Si)N have formed as well. Nitride rings and nodules in the carcass may hinder AIN growth in the composite. Fine-grained residual AhNi and AhShSr are dispersed throughout the composite matrix. The nitride matrix is composed of AIN and (Al,Si)N. Rim replacement of MgO by spine! occurs in the composite. Aluminum nitrides in the metallic carcass cathodoluminesce deep violet-blue, unlike non-luminescent AIN in the composite matrix. This distinction in cathodoluminescence suggests a different mode of formation for composite AIN than for carcass AIN. Phase interpretations and textural characterizations deduced from the implementation of sophisticated mineralogical techniques have contributed to the understanding, and will aid in the improvement, of MgO/ AlN-based ceramic matrix compositeprocessing."

Jan 1, 1999

By Russell E. Clemons

Coarse-crystalline granite, quartz syenite, syenite, meladiorite, and anorthosite in the Florida Mountains, southeast of Deming, New Mexico, were originally mapped as Precambrian. They were remapped in 1971 and some of them described as Mesozoic intrusives. Several subsequent papers presented Precambrian and Ordovician ages. Zinc, lead, copper, silver, gold, manganese, fluorite, and barite mineralization in the Florida Mountains invite more extensive exploration. Clarification of ages of rocks and periods of alteration and mineralization are necessary for efficient exploration. Field observations combined with petrographic studies strongly suggest that all the coarse plutonic rocks are Precambrian and most were altered extensively by late Tertiary hydrothermal activity.

Jan 1, 1982

By Guillermo J. Román

The precipitation of copper and zinc as cements from a copper alloys' spent pickling solution has been studied at laboratory and pilot scale, with the objective of designing an economic process to recover both metals and render a solution to be either recycled to the pickling process or treated in a standard fashion and produce a non-hazardous sludge. The sulfuric acid spent pickling solution already containing copper and zinc was used first to dissolve another solid residue originated in the copper alloys foundry to neutralize part of the acidity. The resulting enriched solution was treated separately with two reductants,; sodium borohydride and iron powder varying pH and excess of reductant under constant agitation. Under the best conditions, precipitation of over 95 percent of zinc and copper was achieved together with the reduction of lead and cadmium contents respectively. A process for the combined residues treatment is proposed.

Jan 1, 1995