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By Lifeng Zhang

Printed circuited boards contain considerable quantities of valuable metal, while also containing many environmental pollutants making them unsuitable for landfill. In this study the decomposition of common plastics used in printed circuit boards were studied. Polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC) and polyethylene (PE) were heated in both C02 and argon atmospheres using a thermo-gravimetric furnace (TG) coupled to a mass spectrometer (MS). Soda ash Na2C03 and baking soda NaHC03 were used as reactants. The degradation temperatures and evolved gases are presented for single plastics and mixtures. Mixed plastics are shown to behave as a sum of the individual plastics. The mass loss temperature is the same in CO2 and argon. However, less residue is formed when heated in CO2.

Jan 1, 2008

By Francis Vanbellen

Umicore Precious Metals Refining operates an integrated precious metals smelting and refining plant in Hoboken, Belgium. Once a smelter and refiner of complex concentrates, the plant today?s feed consists exclusively of industrial and consumer recycled products, making it the world?s largest recycling facility for precious metals. Unlike the fairy tale of the Frog Prince, it took much more than a princess? kiss to successfully realize this makeover. A completely renewed plant has been built over the past decade. The most visible technological innovation was the commissioning of the Pb-Cu smelter. Its flexibility towards very different types of feed makes it perfectly suited as main entry to the Hoboken flow sheet. A new Cu-leaching & electro winning plant and precious metals refinery make up the Precious Metals Operations (PMO) whose targets are fast throughput and maximized yields for gold, silver and the platinum group metals. The Base Metals Operations (BMO), flexibly process the by-products from the PMO, valorizing ?impurities? like indium, tellurium, selenium and others. Off gas and waste water treatments ensure compliance with strict environmental standards. Precious metals recycling is an art that goes beyond mastering a unique flow sheet. Umicore Precious Metals Refining offers a complete recycling service, taking care of sampling and assaying, metals management and logistics. The quality of this integral service is recognized through the attribution of ISO certifications for our operational activities, sampling and the environmental care. And it?s an art that follows Michelangelo?s experience: ?Art is 5% of inspiration and 95% of transpiration.?

Jan 1, 2006

By Malti Goel

"The cost-effective capture of carbon dioxide (CO2) from the point sources for its reduction the atmosphere offers many challenges in materials science. Novel CO2 capturing approaches using chemical, physical and biological methods are in the research stage and are aimed to minimize the cost. Appropriate materials development , which can withstand required temperature or pressure as the case may be for CO2 emanating from coal gas or industrial waste gases form the minimum condition. Other requirements are reclyclability of material and cost of separation. Nano-material composites can be more effective in selective capture of CO2 and can offer solutions for large-scale separation process. Nano-porous material catalysis can enhance the reaction rate of CO2 with other chemicals and thus help in capture of CO2 and convert it into value added products. This paper reviews recent industrial scale developments. In the Indian context, R&D priority areas in CO2 capture process development with a focus on energy industry are presented.IntroductionScience of Climate Change is growing at an enormous pace. With the ultimate goal of stabilization of greenhouse gases in the atmosphere, new scientific approaches are being researched worldwide. A shift in policies from low carbon and no carbon energy sources to fossil fuel sources with capture of carbon and its permanent storage is taking place. The process of carbon capture is both energy and materials intensive and the cost of power generation may increase up to 40% when carbon capture and storage (CCS) technology is implemented. Development of cost effective R&D technology therefore remains the greatest challenge before the scientific community."

Jan 1, 2009

By Shadia J. Ikhmayies

"Tin oxide (SnU2) thin films of thicknesses in the range 100-600 nm were prepared on glass substrates by vacuum evaporation at ambient temperature. The films were characterized by transmittance measurements, X-ray diffraction (XRD), scanning electron microscope (SEM) observations and energy dispersion X-ray analysis (EDAX). It is found that the films have high transmittance and non sharp absorption edges. XRD diffractograms showed that the films are amorphous and the SEM micrographs showed that the surfaces are smooth, uniform and well covered with the material. The EDAX analysis showed that the films are deficient in oxygen. Indirect optical bandgap energy and Urbach tailing in the bandgap was observed, and the width of the tail, which is related with disorder and localized states, was estimated.IntroductionTin oxide is an n-type wide bandgap semiconducting material with a direct bandgap energy of 4 eV and an indirect bandgap of 2.6 eV [1], where inherent oxygen vacancies act as an n-type dopant [2], Tin oxide thin films have been used for transparent electrodes in photoelectric conversion devices namely amorphous silicon solar cells, liquid crystal displays, gas discharge displays, etc. [3]. Perfectly amorphous thin SnO2 films show good electrical response to reducing gases in air and could, hence, be applied to construct semiconductor gas sensors where the metal oxide films function as a monograin-eqivalent active layer [4]. Amorphous SnU2 can also be used in extended gate field-effect transistors (EGFET) as a pH sensor, where the sensitive part is made of the SnO2/Al structure. This device can be used to detect and to quantify any kind of substance that can produce or consume protons, like an enzymatic reaction, therefore showing a large range of applications as biosensors [5].There are different methods to prepare SnO2 films, such as atomic layer deposition (ALD) [6], reactive magnetron sputtering [7], chemical vapor deposition [8, 9], dip coating [10], spray pyrolysis (SP) [3, 11-14], and evaporation [8], The thermal evaporation method was chosen to produce SnO2 thin films in this work because deposition by this technique does not present any compositional problems. In addition, it is a low temperature technique, which increases the probability of producing amorphous films. To increase this probability, the films were deposited at ambient temperature."

Jan 1, 2012

By Olli Hyvärinen

The capacity of Outokumpu Pori Copper Refinery has been increased by 50 % to 70 000 t/a in the last five years by adopting periodic current reversal, reducing spacing and installing some new cells in the old tank house building. Five years operation of PCR has proved that it is possible to achieve additional capacity with PCR and yet produce high quality cathodes. The impurity level in anodes has considerably increased, and recently, arsenic, antimony and sometimes bismuth have displaced nickel as the most critical impurity.

Jan 1, 1987

By Gus Van Weert

The cost of oxygen is a major and common factor in the hydrometallurgical processes developed or proposed tor the oxidation of refractory pyrites. This cost involves charges for the generation and the transfer of the 02 to the mineral slurry. Bio-oxidation faces considerable design demands which require large scale equipment to be resolved. Nitric acid assisted oxidation offers low cost oxygen units; this method of pyrite oxidation deserves a closer look for large scale plants treating pyritic gold ores and concentrates.

Jan 1, 1990

By Lennart Hedlund

There is today a long and well-documented experience of the use of Boliden "Kaldo' technology for treatment of various feed matedals. The process is In commercial' operation in the Boliden Mineral's Rönnskär plant In Sweden for treatment of copper scraps and lead concentrates (In campaigns). This plant was built In 1976 for treatment of lead dusts from the copper plant but later modified to take other raw materials. Boliden's Kaldo techr:lology Is also In operation since 1991 for treatment of low-grade copper scraps In Enlrlsorse's plant In Porto Marghera (Venice), Italy. The plant is producing 25 000 tons of blister copper ,per year. The Kaldo furnace Isa high :Intensity smelting unit, where several successive treatment steps can be done In the same vessel. The furnace can be totally enclosed to protect the working environment, and the small off-gas volume can easily be dedusted. Input materials can vary over a very wide range, the products will be a dump slag with low (0,5%) copper and lead contents and black copper or blister copper. The dust from the process can be used for zinc production. A new development is autogenous smelting of scrap in a Pierce-Smith converter, implemented at Compagnie Générale d' Èlectrolyse du Palais in France.

Jan 1, 1995

By Atinuke Oladoye, David Esezobor

"Particulate Copper Silicon carbide (Cu-SiCp) composites find application as wear and heat resistant materials in electrical sliding contacts such as in homopolar machines, railway overhead current collector systems where high electrical/thermal conductivity combined with good wear properties is required. However, challenges occur during machining due to the presence of hard reinforcement in the matrix. This may lead to high turnover of tool wear and poor surface finish. The adoption of near-net shape technology to produce such hard-to-machine metal matrix composites and subsequent finish machining with its attendant cost has reported limited success. This paper critically appraises the challenges and opportunities in the improvement of tribological characteristics of particulate Cu-SiC composites and identifies low cost reinforcement material that could be used to improve its tribological characteristics.IntroductionTribology consideration is increasingly becoming a decisive factor in the design and selection of materials for applications involving interacting surfaces in relative motion. The consideration is mainly on the combined effects of friction and lubrication on material's wear integrity and performance amongst other. Annual losses due to tribology in the US industries are estimated at between 1-2% of the Gross National Income [1], in Russia it is about 1-4% of the GDP [2]. Thus, the attributes of tribology has become imperative in modem machinery especially those applications involving sliding and rolling surfaces, and electrical contacts [3- 8].These are readily found in homopolar machines, internal combustion engines, aircraft engines, gears, cams, seals and railway overhead current collector systems [9-12]. In these systems, the dissipation of frictional heat arising from the interacting surfaces as quickly as possible imposes constraints on the choice of materials for such application to prevent softening, plastic and shear flow and the transfer of metal as wear debris onto the interacting surfaces. If these possibilities occur, system performance is compromised and premature failure may result. Materials for these systems are expected to possess high electrical and thermal conductivities, low coefficient of thermal expansion, good corrosion resistance and high melting point [3-8, 13]."

Jan 1, 2011

By Eric J. Grimsey

Nickel smelting and converting can be viewed as processes in which iron is either partitioned or transported between matte and slag. Metal recovery depends on the mass of iron transported to slag, the thermodynamic environment in which the transport is made, and the extent to which the slag, once formed, is left in contact with the matte. The importance of these effects is discussed with reference to a new equation which describes metal recovery in terms of a mass balance and a thermodynamically related parameter which is easily measured in practice.

Jan 1, 1993

By Pedro A. Netto, Giulio R. Altoé, Sergio N. Monteiro, Ygor M. Moraes, Frederico M. Margem, Gabriel O. Glória

Since environmental issues are becoming more and more important Worldwide. Nowadays, Natural fibers are been used to substitute the synthetic ones. Although PALF fiber is an important natural fiber and its mechanical Properties surpass in various aspects some other lignocelluloses fibers, such few studies have been conducted with the fiber obtained from leaf of PALF plant. In order to better evaluate the mechanical properties and possible applications, this paper aims to improve the elastic modulus of the PALF fiber by Weibull statistics, by evaluating their mechanicals properties and possible applications. The fibers were divided in diameter intervals and the tensile strength and elasticity modulus were measured in each range. The fractured surface was examined using scanning electron microscopy. The results, interpreted by the Weibull statistical method, showed a correlation between the fiber elastic modulus and its diameter.

Jan 1, 2015

By I. Gaballah

Decontamination of synthetic solutions of PbC12 containing 10, 100 and 1000 ppm of lead, using chemically treated barks had been studied. The percentage of !cad cations' removal from solutions depends upon the pH and the initial concentration. About 99 % of the initial lead content can be removed at pH of about 3.5, 5.5 and 6.5 for initial concentrations of 10, 100 and 1000 ppm respectively. The maximum retention capacity of the treated bark is about 83 mg of lead per gram of modified bark. Bark loaded with lead had been analyzed by Infra Red spectroscopy. It seems that lead reacts with hydroxyl groups of the phenolic constituents of the bark. On the other hand, the removal of a lead cation by the bark leads to the release of two H+. This seems to show that the removal of lead could be interpreted as an ion exchange with hydrogen belonging to the hydroxyl groups of the modified bark.

Jan 1, 1994

By V. M. Paretsky

The basic work conducted by Prof. A.Yazawa has demonstrated that in order to ensure single-stage white metal production by autogenous smelting of copper sulfide raw materials, it is most favorable to use highly basic slags, in particular oxide systems CaO-FeO-Fe2O3-Sio2. he special studies have been conducted in the Gintsvetmet Institute to investigate the composition and structure of slags produced on a semi-commercial scale when testing the KFP and FBP processes for white metal smelting, as well as the slag obtained in a full-scale KFP furnace at the Almalyk copper smelter. The investigations conducted have demonstrated why production of high-grade matte or white metal is associated with lower loss of copper in slag in a series: silicate slag I silicate-calcium slag I ferrite-calcium slag.

Jan 1, 2003

By R. J. Wesely

The paper describes the various methods which are currently being used or considered to refine gold and silver. These methods are then compared on a technical and economic basis. Conclusions are drawn on the factors which might influence the choice of process for different feed stocks and economic constraints

Jan 1, 1990

By J. W. Evans

Mathematical modeling has now become a standard technique in the development of new technology and the improvement of existing technology in the processing industries. Physical modeling has a longer history but a smaller following at present. The paper reviews some examples of the application of both types of modeling in non-ferrous metal extraction, particularly within the copper and aluminum industries. The objective is to show that well founded models can lead to results that have practical consequence in scaleup, design and operation.

Jan 1, 1993

By D. G. Hattingh, A Els-Botes

"Considerable information is available on the factors influencing the iron-zinc reaction rate at 450° C of low carbon steels, in comparison there is a scarcity _of similar fundamental information of spheroidal graphite irons. This can be attributed to the more complex microstructure and ferrous alloy chemical analysis of spheroidal graphite irons. Hot-dip galvanizers have identified the complexity in controlling and predicting the thickness of the galvanized coating formed on commercial cast irons, which has serious financial implications for both the galvanizer and customer.Commercial hot-dip galvanizing has been in use for over 160 years and yet an elementary understanding of the dynamics associated with the hot-dip galvanizing of spheroidal graphite cast iron is still insufficient. To allow the. process to become a modem surface engineering technology, the fundamental aspects of the process must be thoroughly understood.When a clean iron or steel article is dipped into the molten zinc, zinc initially solidifies around the steel or iron. As heat is transferred to the article form the bath, this initial solidified zinc layer remelts and a series of iron-zinc alloy is formed by the reaction of the zinc with the surface of the article; on removal from the bath, some of the molten zinc is taken out on top of the alloy layers. At normal galvanizing temperature (450 °C), the reaction between iron and zinc is usually parabolic with time. The rate of reaction is rapid at first but then slows down and the coating thickness does not increase greatly if the article is immersed in the bath for longer times(1)."

Jan 1, 2000

By Krishna Parameswaran

This paper discusses sustainability considerations in primary copper smelting using selected examples of practices at ASARCO LLC, an integrated U.S. primary copper producer. Using the classic Brundtland Commission definition of sustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copper mining and smelting practices can be made sustainable. The examples used to illustrate sustainability considerations include: (1) adoption of flash smelting; (2) emission reduction and process improvement associated with anode refining of blister copper and the converter retrofit project, and (3) preliminary research findings on alkali treatment of copper smelting slags and copper mine tailings.

By John W. Graydon

Incineration is an attractive alternative to the disposal of MSW in landfill sites. However, the process of incineration generates fly ash which contains significant levels of leachable heavy metals - particularly cadmium, lead, and zinc - and it is essential to manage this fly ash in an environmentally sound manner. The compositions, phases, textures, morphologies and size of fly ash particles have been studied by light microscopy, scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. The detailed spatial relationships and speciation of the environmentally significant constituents have received particular emphasis. The information obtained is useful in understanding how fly ash is formed during incineration, in understanding the leaching behavior of untreated fly ash if it is disposed of in a landfill and, most importantly, in guiding the development of the best treatment strategies for fly asti to mitigate its environmental impact.

Jan 1, 1992

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 John R. Howell

"SUMMARYThe process of producing a new cast component requires significant design and development by both the design engineer and the foundry engineer. This effort strives to produce a high quality component at minimum cost. To assist in this development, an analysis system, consisting of several computer programs, has been developed to simulate the metal casting process. This system incorporates analytical geometric solid modeling, finite element analysis, results display, and an innovative technique to model the casting mold with surface boundary conditions.The simulation has produced excellent thermal results and work is in progress to develop techniques to enable use of this data in additional analyses to predict porosity and residual stress. Research is required to produce working parametric formulations of material properties. Software development is required to develop good fluid flow analyses for large. 3D models to simulate filling of and convection in molds.Integrating this system of programs is difficult due to proprietary database structures used by software developers. However, an acceptable means has been accomplished' to move data from one program to another. Further software development is required to facilitate this task. INTRODUCTIONThe process of producing a new cast component requires significant design and development by both the design and foundry engineer. This effort strives to produce a high quality, reliable component at minimum cost in a timely manner. The design engineer needs to know the physical and mechanical properites which can be expected in the actual part at critical areas. This will enable him to design a part with minimum material while fulfilling the performance required. The foundry engineer needs to produce a sound, quality casting with a minimal amount of material In risers, the feeding system and machining stock. This must be done with a minimum· investment in tooling and development time and maximum productivity of labor and capital employed. This task Is continually being made more difficult because of increased competition in the marketplace and the use of castings in more severe service. This has strongly influenced the need for high quality castings.The task of developing a new casting is difficult for both the design and foundry engineer. To assist in this development, Deere & Company has been engaged in the development of an analysis system to simulate material processes. A major portion of this program involves simulation of the metal casting process. This analysis system has evolved into a package of computer programs which simulates casting solidification and subsequent cooling through the finite element method"

Jan 1, 1986

By Sebastian Schmuck, Petrico von Schweinichen, Dieter Senk, Mohammad Peymandar

"At Department of Ferrous Metallurgy of the RWTH Aachen University in Germany steels in the system Fe-Mn-C(-Al) are investigated and produced in the framework of the SFB 761 ""steel-ab initio"". A new world of steel grades leads to special challenges regarding the production and recycling at the end-of-life cycle of product. In order to recycle high manganese steel alloys the EAF has to be chosen preferentially. A good slag practice is necessary avoiding loss of manganese content during melting in the EAF. This paper investigates on the reaction kinetics at the interface of slag and steel containing Mn (17-22 wt.-%) and up to 3 wt.-% Al. The effect of changes in the composition of slag and steel on the interfacial reaction kinetics is studied. The thermodynamic software FactSage™ is utilized to calculate the composition of slag and steel at equilibrium.IntroductionTRIP and TWIP steels are highly alloyed steels which show superior strength and ductility when compared to standard carbon steel and stainless steel alloys. These TRIP- and TWIPsteel grades contain typically 15-30 wt.-% manganese, 0-4 wt.-% silicon and aluminum, and up to 1 wt.-% carbon. Steels containing 18-28 wt.-% manganese and 0.7-1.2 wt.-% carbon together with aluminum addition from 3 to 12 wt. -% and without silicon refer to TRIPLEX high manganese steel alloys. These alloys combine high strength at even large ductility [ 1-4]. At the Department of Ferrous Metallurgy (IEHK) of the RWTH Aachen University in Germany, steels in the system Fe-Mn-C(-Al) is under investigation at the collaborative research center, SFB 761 ""Steel-ab initio"". In this project, high manganese alloyed TRIP and TWIP steels are in the focus.The mechanical properties such as high strength and high ductility make this kind of steels perfect candidates for impact absorption applications in auto body such as vehicle doors and bumpers [2, 5]. With increasing the use of TRIP-, TWIP- and TRIPLEX-steels more high manganese steel scraps will be available at the end of life cycle of products, which need to develop the technologies and metallurgical processes to recovery of high manganese steel. A new steel grade brings new challenges in recycling. In order to recycle high manganese steel scraps the electric arc furnaces (EAF) have to be chosen preferentially [1]. Nevertheless it's not easy to prevent the manganese loss during the process in EAF. During the oxygen refining of high manganese molten steel in EAF the manganese content decreases strongly by oxidation and vaporization, which is affected by slag composition, slag properties such as basicity and viscosity, slag weight as well as melt temperature [6-8]."

Jan 1, 2014