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By Jorge Alberto Soares Tenório, Viviane Tavares de Moraes, Denise Crocce Romano Espinosa, Franco Alves Lavacchini Ramunno

"The traditional process for recovery of metals from waste electric and electronic equipment (WEEE) usually involves pyrometallurgical processing. However, the application of this technology to processing waste printed circuit boards (WPCBs) might lead to the formation of dioxins and furans, due to thermal degradation of flame-retardants and polymeric resins present in the board substrate. Therefore, this paper proposes a hydrometallurgical route for the recovery of copper. The acid leaching behavior of copper has been investigated at three different temperatures (25°C, 50°C and 75°C) with and without the addition of an oxidizing agent (hydrogen peroxide - H202). The dissolution kinetics for acid copper leaching was calculated based on chemical analysis by ICP-OES (Inductively Coupled Plasma - Optical Emission Spectroscopy). At 50°C with 1 mol/L H2S04 added 10 mL H202 (30%) each half hour under pulp density of 1 g I 10 mL, 100% of copper was extracted after 3 hours. The dissolution kinetics of copper with H2SO4-H2O 2 followed 1 - (1 - X)113 =Ket, i.e. chemically controlled reaction model.IntroductionThe information regarding the generation of waste electric and electronic equipment (WEEE) are still difficult to obtain because the estimates should take into consideration the historical production and sale of various products and the rate at which they reach the end of their life cycle, whose duration depends on the behavior of consumers [1]. Thus, the estimated overall WEEE generation varies between 25 and 50 million tons each year, which corresponds to more than 5% of all municipal waste generated [2], and this amount will increase at a rate of 3 to 5% per year, approximately three times faster than other individual types of waste [3].Printed circuit boards (PCBs) are essential parts of electric and electronic equipment (EEE), being found in virtually all electronic products, as well as in weapons systems [4]. A PCB is a basic component, which consists of a board where copper tracks are deposited. While the board behaves as an electrical insulator, the tracks connect electrically the various components attached to the board [ 5]. In addition to glass fibers, paper and resins, the PCBs contain significant amounts of metals, such as copper, iron, nickel, lead, stain, silver, gold and palladium [6]. In general, the weight fraction of metal is around 28% and the remainder of the boards is composed of plastic (19%), bromine (as flame retardant - 4%) and ceramic material (49%) [7]."

Jan 1, 2014

By J. P. Evans

The modem 'copper smelter today utilizes tonnage oxygen for smelting concentrates. ,generating a high strength S02 off-gas leaving the smelter vessel. This gas stream. which also contains any unreacted oxygen, plus CO2; N2 and H20. also carries with it the volatilized portion of heavy metals in the feed, plus partly oxidized sulfide concentrates, The time/temperature history and subsequent treatment of this off-gas stream emerging from the smelting furnace exit up to the acid plant can influence the partitioning and segregation of heavy metals, in the off-gas circuit. Depending on this history. the type and characteristics of the chemical and physical reactions which occur in the gas handling system 'can be influenced. This fact can also be used as a tool to adjust the separation of copper from heavy metals. In this paper, the impact of different time/temperature histories of the gas, due to different furnace geometries and design. on the subsequent formation and characteristics of the smelter dust is examined. Based on the available data. several case histories drawn from examples using both bath and flash smelting technologies are analyzed from this perspective.

Jan 1, 1992

By Clemens Schmetterer, Patrick J. Masset

"The surface tension represents an important property for the modelling of high temperature processes. In this study the surface tension of two Al2O3 – CaO – SiO2 model slags and the influence of the admixture of 5 up to 30 wt.% FeO were studied. The surface tension measurements were carried out using the sessile drop technique on BN substrates under Ar atmosphere (10-6 atm O2) up to 1500 °C.IntroductionThe aim of VIRTUHCON1 is the virtualization of high temperature conversion processes, a task that requires thorough understanding of these processes. In many of these conversion processes slag plays an important role to control the properties of the product, to protect the reactor lining or simply as waste. Slag surface tension is one of the materials properties that is needed for the description of such processes, since it influences the interactions between the components in the reactor, e.g. at the slag – Fe interface in the blast furnace.Surface and interfacial tensions have thus received considerable attention in research, but the number of investigations in this particular pseudo-quaternary system is surprisingly low. Furthermore, the literature data are subject to different measurement conditions and techniques which complicates the data analysis and comparison.The slag atlas [1] offers a compilation of the available literature until 1986 (shown in Table I), but literature search has not revealed more recent studies of this system until now. For example, Elliott and Mounier [2] determined the surface tension of ACSF slags using the double tube maximum bubble pressure technique at 1200 °C. They kept their slags in contact with Cu-S-F mattes, and the slag therefore contained a certain amount of sulphur which acts as a surfactant and lowers the surface tension. The compositions of their slags were scattered over a wide composition range and they did not use a common ACS base mixture for their tests, either. The surface tension values vary between 417 and 446 mN/m, but due to the reasons just mentioned no trend in the measurements can be observed and the influence of FeO admixture on the surface tension cannot be deduced. Further information including the temperature dependence is available from Pavlov et al. [3], Ishchanov and Shushkov [4] and Murav’eva and Kaplun [5]; the diagram on page 446 in Ref. [1] has been drawn from these sources. Both positive and negative temperature coefficients are reported in these works. SiO2 is the only pure constituent that has a positive temperature coefficient [6], but a correlation of the temperature coefficient with the SiO2 content was not found to be conclusive."

Jan 1, 2011

By Zhihe Dou

SHS reaction system has advantages of heat flux density, energy concentration and reaction speed, with sufficient conditions in thermodynamic and kinetic reaction. This paper invented a new technology of SHS metallurgy of preparing melting point alloys and refractory compounds using its own chemical energy. SHS-leaching process for preparing nano boron powder or ultrafine boride powder and SHS-casting process for preparing titanium-based alloy and immiscible alloy were studied. The results indicate that highly active boron powder of greater than purity of 93%, particle size less than 100nm and purity greater than 98.5%, particle size less than 400nm REB6 can be prepared. With SHS-Casting process, the oxygen content of less than 0.59% ferrotitanium, oxygen content of less than 0.5% titanium alloy and ?40-80*100mm large size of CuCr, Cu-Fe alloy ingots were prepared. This technology has greatly enhanced the thermal reduction method added values of preparing metallurgical products and its competitiveness.

Jan 1, 2014

Acid mine drainage containing heavy metal ions is a large environmental problem facing the mining and mineral processing industry. The femte coprecipitation is a novel technique for removing heavy metal ions from waste water, recently applied to acid mine drainage. The fenite precipitation is usually performed at high temperature and therefore if applied in conventional manner, it becomes uneconomical to treat large quantities of acid mine drainage. In this paper the ferrite precipitation at ambient temperature-is &died. The possible mechanism of ferrite formation is discussed Experimental results from Noranda Tailing and Berkeley Pit water treated by this process are presented.

Jan 1, 1994

By Jiling Wang, Xuefeng Liu, Haojian Duan, Lifeng Zhang, Ying Ren, Wen Yang

"In order to study the influence of MgO-C refractory on steel cleanliness and inclusions during steelmaking process, and to understand the reaction mechanism deeply, laboratory deoxidation and equilibrium experiments were respectively performed in MgO crucibles at 1873K. In the former experiment, after Al addition, steel samples were taken at different holding time. In the latter experiment, different slag components and different contents of carbon and aluminum in steel were considered respectively. The inclusion characteristics of each experiment were analyzed. The results showed that with the increasing of holding time after deoxidation by Al, MgO existed in the small inclusions firstly, and then in the large ones such as the clusters. The MgO content in the inclusions increased with the increasing of holding time, indicating that the MgO in crucible could be individually reduced by the aluminum in the molten steel. The reaction could occur within nine minutes.IntroductionNon-metallic inclusions would have positive or negative effect on steel quality depend on the quantity, size and composition of inclusions. Large inclusions are always detrimental. From the point of view of inclusion property, plastic inclusions are required by steel cord, while hard inclusions are preferred by pipeline steel. One of the most important ways to increase the steel quality is reducing the inclusion size and controlling the inclusion composition in steel. Nowadays, MgO based refractory is used as ladle glaze material with more and more frequency, which results in different inclusion characteristics in molten steel, for example, the inevitable generation of MgO contained inclusions during ladle treatment of steel. In other words, the inclusions in this type ladle will influence on the steel cleanliness and the product property. Thus, keeping an eye on the inclusion formation behavior in the steel with MgO-C ladle glaze is important for the steel industry. There have been a few studies in this regard. Li et al[l] studied the reactions between MgO-C refractory, molten slag and metal using a high temperature X-ray radiographic apparatus. They found that the local corrosion was regarded as due to the cyclic dissolution of MgO and graphite in the refractory into slag and metal phase. The gas bubbles formed according to the reaction of (FeO)+C(s)=Fe(l)+CO(g) greatly influenced the corrosion. On an industrial scale, Du[2] found that ladle glaze is a major source of inclusions in the ladle. An experimental study has been performed by Lehmann in order to estimate the importance of the reaction between a MgO-based tundish refractory and an Al-killed steel[3]."

Jan 1, 2014

By Lucas Lopes da Costa, Sergio Neves Monteiro, Rômulo Leite Loiola

"Composites with DGEBA/TETA epoxy matrix reinforced with thinner and continuous bamboo fibers stripped from culms were mechanically characterized by tensile tests. Specimens with up to 30% in volume fraction of aligned fibers were tensile ruptured at room temperature. The results showed a steady increase in both the ultimate strength and the elastic modulus of the composites with the amount of incorporated bamboo fibers. The fractographic analysis by scanning electron microscopy showed evidence of moderate adhesion between the bamboo fiber and the epoxy matrix. This fiber/matrix adhesion by interaction mechanism apparently justifies the improved tensile properties of the composites.IntroductionIn recent years polymer composites reinforced with natural fibers, mainly those lignocellulosic obtained from plants, have been subject to extensive research works [1-5]. Environmental, economical, societal and technical advantages of these composites are motivating their substitution for similar polymer composites reinforced with synthetic fibers. In particular, R & D efforts have been conducted aiming to replace glass fibers composites that are comparatively more abrasive to equipments, non-recyclable, more expensive, heavier and toxic [6]. Among the many lignocellulosic fiber composites being investigated, those fabricated with bamboo stripped fibers, i.e., fibers longitudinally cut from the culm, still need information to support possible industrial applications. Several works, however, have been dedicated to bamboo stripped fibers as possible reinforcement of polymer composites [7-17]. These works reported mechanical properties that could markedly vary with the type of polymer matrix, the fiber disposition (if continuous, aligned, short-cut, mat interlayered, etc) and the test condition."

Jan 1, 2011

By Xueming Lv

The rotary kiln-electric furnace (RKEF) process is the main method for producing ferronickel from nickel laterite ore. However, this process is energy intensive as it involves several high temperature steps. Therefore, a novel process is proposed to directly produce ferronickel from nickel laterite ore by semi-molten reduction, which is expected to be realized in a rotary hearth furnace (RHF). The RHF process is able to shorten the flow sheet, decrease the reaction temperature as well as reduce energy consumption. In this study, the influence of basicity on reduction of nickel laterite ore was investigated. The results showed that it is possible to produce the ferronickel nugget directly at 1400 °C when the quaternary basicity [(mCaO + mMgO)/(mSiO2 + mAl2O3)] was fixed at 0.60. Under this experimental condition, the grade and the recovery ratio of nickel reached 11.53% and 98.59%, and the grade and recovery ratio of Fe were 84.16% and 68.72%, respectively.

By Nickolas J. Themelis

Nearly thirty two million tons of municipal solid wastes (MSW) are combusted annually in over one hundred U.S. Waste-to-Energy (WTE) power plants, thus reducing the use of fuel oil by about 1.6 billion gallons of fuel oil. One of the advanced WTE processes is the 0.9-million ton/y SEMASS facility at Rochester. Mass. Most of the combustion in the three giant combustion chambers occurs while the injected shredded wastes are in suspension, i.e .? in flash combustion mode. The velocity. temperature, and concentration profiles in the SEMASS combustion chamber were simulated by representing the combustible fraction of MSW by the simplified formula C6HIO04 and using the CFD program Fluent to solve the turbulent energy and mass transport equations. After validation against plant data. this model will be used to examine options for increasing the productivity of WTE combustion chambers, such as optimum distribution of primary and secondary air and oxygen enrichment.

Jan 1, 2003

By S. L. Kher

The Singhbhum Copper Belt located in the state of Bihar in Eastern India bears evidence of ancient workings and indicates the existence of a civilized habitation in this region in the past. It was in 1833. how- ever, that the first official announcement of the occurrence of copper in the district was made. Although the occurrence was confirmed in 1847, it was not until 1857 that the first company was formed to exploit the deposits. This Company was dissolved in 1859 and from then until 1920, there were many unsuccessful attempts to develop and exploit the copper deposits in the Singhbhum area. In 1920. the Cordoba Copper Co. took an option on the Mosaboni area, which is nearly 10 km away from the present works located at Moubhandar, Ghatsila and exercising the option in 1924, purchased the mining rights from the Cape Copper Company. The Cordoba Copper Co. was then converted into Indian Copper Corporation Ltd. This was subsequently taken over by the Government of India in March 1972 and is now known as Indian Copper Complex (ICC), forming one of the two smelting units of Hindustan Copper Ltd.

Jan 1, 1976

By Shu Bin, Lin Chen, Tian-zu Yang, Wei-feng Liu, Wan-da Bin

"Antimony resources are rich in china, its reserves and productions are ranking the first in the world. The Chinese antimony mineral resources are mainly existed in the form of three types, such as stibnite, antimony-gold ores andjamesonite. The antimonial dust that produced from lead smelting process is an important secondary antimony resource. The different process that was adopted to extract antimony depends on the different raw materials. The process of blast furnace volatilization smelting is mainly used to treat stibnite and antimony-gold ores. But jamesonite is treated by the process of roasting-sintering-blast furnace smelting. And antimonial dust is treated in the reverberatory furnace. Many new technologies that are applied in these traditional antimony smelting processes play important roles, such as deleading agent, antimony white production, air-oxidation method, direct-blowing method, bath smelting technology, and so on. At the same time, the development of antimony smelting technology in china is prospected according to the requirement of the state environmental protection.IntroductionThere are five countries that produce antimony in the world, such as china, Tajikistan, Bolivia, Russia, and South africa, but China is the largest country of antimony production in the world. In the world, the antimony productions of 2008, 2009, and 2010 are 182,000 tons, 154,000 tons, and 167.000 tons respectively, but Chinese antimony productions are 166.000 tons, 140,000 tons, and 150,000 tons respectively. So Chinese antimony production was accounted for more than 89% of the world in 2010. It indicates that China have irreplaceable advantages in antimony resource and production all over the world."

Jan 1, 2013

By Gervais Soucy, François Quesnel, Pierre Hovington, Wen Zhu, Karim Zaghib, Jocelyn Veilleux

The properties of lithium titanates anodes in Li-ion batteries are highly dependent on their secondary constituents. While their main phase is usually constituted of Li4Ti5O12, significant quantity of lithium titanates compounds of various stoichiometry are often present, due to either the processing, usage or aging of the material. These may go underreported, as many of these spectrums overlap or display low signal in X-ray diffraction (XRD). Samples of nanosized lithium titanates synthetized by inductive plasma were characterized by XRD and scanning electron microscopy (SEM), as they provide a regular yet typical crystallite size and shape including multiple phases. A Rietveld refinement was developed to extract the composition of these samples. Mass balance through further annealing and differential scanning calorimetry (DSC) enthalpy measurements from phase transformations were also used as identification and validation techniques.

Jan 1, 2015

By R. Burkhard

Recovery of metals from complex mixed wastes is a challenging task of modem material and waste management strategies. Thermal methods are an important tool in this respect. Plasma turned out to be particularly useful for treatment of complex or toxic wastes and residuals. In order to study plasma processes at reasonable costs, a pilot plasma plant has been used and wastes like ~pent Raney-Nickel catalysts, copper and ah.:lminum drosses, and. other metal containing wastes were investigated. The paper summarizes the most significant findings

Jan 1, 1995

By Tatsuo Itou

Both sales volume of Aluminum Can and its recycling rate are remarkably increasing here in Japan. In 1993, recycled can volume was 11.78 billion cans ( 116,258 metric tons ) and its recycling rate 57.8 percent. We, MITSUBISHI MATERIALS CORPORATION. the leading manufacturer of aluminum can in Japan and our affiliated companies are very deeply involved in recycling used beverage cans ( U.B.C ) and recycling them back to can stock. In this paper. I would like to present the following; 1. Recent trend of beverage can consumption in Japan. 2. Trend of aluminum can and its recycling rate in Japan. 3. Future of aluminum can business in Japan.

Jan 1, 1995

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 W. H. (Bill) Jay

The destruction of cyanide creates a significant impost on the financial returns of gold mines. These losses increase substantially when ores containing cyanide-soluble copper are treated. Failure to remove or destroy free or WAD cyanide before it is discharged into tailings dams has, on a number of occasions, led to significant fish, bird and animal deaths. Thus, the retention of cyanide within the leach circuit and the recovery or removal of stable metal cyanide complexes needs to become standard practice for all gold mining operations. Furthermore, reducing cyanide purchases will minimise the quantity of cyanide transported to the mine site thereby reducing the opportunity for spillage of this chemical. Many different physical and chemical methods have been investigated for the removal of cyanide from process solutions. All cyanide destruction methods create a financial impost on the economic viability of the gold mine. To reduce these costs, the recycle of cyanide and the economic recovery of the metals solubilised by cyanide is of prime importance. The alternative methods currently in use, or under consideration for the treatment of copper cyanide, entail high reagent costs, produce the recovered metal in a contaminated form and require the safe handling of hydrogen cyanide. These processes will be briefly discussed within this report Environmental and financial benefits are enhanced by recent laboratory and pilot plant studies conducted by Oretek Limited. The Oretek CPC process for the recovery of copper and the recycle of cyanide from copper cyanide-containing solutions does not require pH adjustment to the alkaline cyanide leach conditions. Copper ions are coordinated to a water-soluble and/or an organic soluble polychelating agent under alkaline conditions and the cyanide ions are displaced Membrane separation, or phase separation of the polychelated copper from the cyanide ions enables the cyanide ions to be recycled and the copper to be directly electrowon from the polychelating polymer. The polychelating polymer is then recycled. Ion exchange resins and solvent extraction systems which may be incorporated into the above process will also be discussed in detail.

Jan 1, 1998

By Jiakai Zhang

Many postconsumer electrical and electronic equipment wastes contain a considerable amount of rare earth elements (REEs); however, the current level of REE recycling from them is limited (<1%). Neodymium–iron–boron (NdFeB) magnets, used at both small- and large-scale, from computer hard disk drives and small tools to wind turbines and cars, are a good example of such waste materials that contain high content of neodymium (Nd) and dysprosium (Dy). These elements are considered critical metals because they are the main building block of emerging green technologies that will allow for GHG emission reductions. Because demand for these green products is increasing around the world, the demand for REEs is increasing quickly, putting their supply at risk in the near future. Thus, it is critical to develop efficient, robust, and cost-effective processes to recycle these elements from this class of electronic waste materials. Here, we performed a thorough characterization of a N52–NdFeB magnet to identify its composition, crystal structure, and morphology. Furthermore, we developed an efficient hydrometallurgical process to extract Nd and Dy with high efficiency (more than 95%).

By Richard A. Leiby

The recycling of lead-acid batteries in the United States has become a challenge as to how to balance ever increasing environmental regulation and cost with efficient operations. East Penn&apos;s captive secondary lead smelter has developed into a recycling facility producing lead, polypropylene, sulfuric acid, ammonium bisulfite, and non-hazardous discard slag. The emphasis has been to design a facility to comply with environmental regulations, to eliminate wastes, and to produce products, while at the same time, continuing to supply the company&apos;s battery manufacturing raw material needs.

Jan 1, 1993

By Eiji Iwamura

"Two types of diamond-like carbon (DLC) films with different microstructures were prepared by unbalanced magnetron sputtering, and the tribological properties of the nanoscaled DLC multilayer coatings consisting of alternating layers of graphitelike and amorphous-like microstructures were examined. The DLC microstructure was characterized by certain features of graphite-like clusters, in that some of them had onion-like structures. The films filled with the clusters were obtained in a condition with an incidence of high influx of energetic electrons, and the other films without apparent cluster structures were formed in a condition with ion bombardment controlled by negative bias voltage applied to substrates. Stacking each film layer-by-layer, the nanoscaled multilayered coatings showed superior tribological properties to individual single-layered films due to the combination of properties induced by the difference of microstructures.IntroductionIn various tribologiql applications, it is necessary for diamond like carbon (DLC) coatings to have adequate adhesion, significant hardness and a concomitant low friction coefficient. A number of deposition techniques and coating structures have been proposed to achieve suitable DLC properties [1-3]. However it is still difficult to obtain a satisfactory level of combination of the properties particularly desirable for engineering applications.In this study, the features of unbalanced magnetron sputtering were demonstrated with the effect of ion and electron bombardment. Two types of microstructures , namely amorphous-like and graphite-like, were prepared by changing the condition of the charged particles bombardment during deposition. Using the difference of properties induced by the microstructures, nanoscaled DLC multilayered structures were examined in an attempt to improve tribological properties."

Jan 1, 2000

By M. A. Cocquerel

The future economic necessity of mining copper ores with a high impurity content and increased environmental awareness will require closer examination of the distribution of arsenic within copper smelting processes. A generalized approach is developed which can be adapted to specific projects for the determination of an overall process configuration to satisfy all requirements in a cost effective manner.

Jan 1, 1983