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By Felipe Costa Hashimoto Bertin, Jorge Alberto Soares Tenório, Rodrigo de Souza Dalti Pereira, Denise Crocce Romano Espinosa

"The increasing amount of portable devices and their fast obsolescence generates an increasing quantity of discarded batteries. The recycling process of discarded batteries allows the recovery of metals for further use and avoids the contamination of soil and water. Even though there are several researches on the topic, few papers focus on mixed batteries. The purpose of this work is to characterize a mass of collected mixed batteries and study the hydrometallurgical process of recycling. The specific leaching parameters studied were pH, temperature and reduction potential. The specific goal was testing the selectivity of pH for leaching each metal. The results show that the optimal leaching occurs in acid solutions with negative pH at IM of sulfuric acid and at room temperature (25°C).IntroductionThe increasing portability of electronic devices in the past century along with their fast obsolescence produce tons of discarded materials yearly that could be recycled generating new materials for the industry. For example, metals such as cobalt and nickel, that are worth respectively US$ 30.00 and US$ 16.10 per kilogram[l,2] are disposed in urban trash yearly, which means that millions of dollars are thrown away instead of being recovered and reused[3].Besides the obvious fact that the society is throwing money away, most of these metals are toxic for the environment and all mammals, so when badly stored after use they can be found contaminating ground water which will contaminate the entire lifecycle. Some of these metals can cause cancer, serious lung problems and have bioaccumulative properties [4] resulting in lower productions of natural products and maybe death for consumers.So in compliance to new regulations such as the National Solid Residue Politic (PNRS) and the CONAMA-Resolution N°401 from November of 2008[5]- (that follows similar restrictions and regulations as the European directives) all those urban and electronic wastes need to be correctly disposed and treated before being thrown away on local dump sites.In Brazil the national rate of garbage recovery is around 70%, which only 5% is properly recycled, accordingly to the research of the UFSC, also electronic waste grows at 5% per year [6]The present study was motivated by the fact that recycling processes for batteries are not spread through the country and by the fact that most papers do not try to recycle a mixed mass of batteries, but a specific mixture which does not represent the composition of traditional household wastes."

Jan 1, 2014

By Karl A. Gschneidner

The magnetocaloric effect has been known for 120 years and has been utilized for cooling about 70 years. But in the last four years significant advances have been made to show that magnetic refrigeration is a viable and competitive cooling technology. Most of the work has focused on reciprocating devices, but rotary apparati are being developed. To date the magnetocaloric properties have been characterized for more than 200 materials. The magnetocaloric effect behaviors have been classified into three types of behaviors. The most common one is found in magnetic materials which exhibit a second order magnetic phase transition. Magnetic materials which exhibit a first order magnetic phase transition account for the second group of materials. Materials which exhibit multi-magnetic phase transitions make up the third group. The best candidate materials for magnetic cooling over the range from -4 to -1 350 K are also presented.

Jan 1, 2002

By Kimiaki Utsunomiya, Yasumasa Hattori, Yoshiaki Mori, Toyokazu Okubo

"The effect of various operating conditions on splashing behavior in a Peirce-Smith converter has been investigated with a 1/5.7 scale cold model. Dynamic similarity between the model and a commercial converter was attained by setting the modified Froude number in the model experiments in· the range for normal converter operation. It is known that for a given modified Froude number the dimensionless penetration length of gas into the liquid phase increases as the liquid density decreases. Moreover, penetration· length has a large effect on splashing behavior. Therefore, a heavy liquid, a mixture of water and lead concentrate was used as the liquid phase. It was concluded that the amount of splash dramatically decreases with a reduction in the buoyancy energy per, unit liquid mass and an increase in the horizontal distance between the tuyere tip and the edge of the mouth.IntroductionSubmerged gas injection is widely used in practice in ferrous and nonferrous pyrometallurgical operations to achieve large gas-liquid contact areas and good agitation of liquid for rapid chemical reaction. The common application in ·nonferrous industry is the Peirce-Smith converter with multi-tuyere for copper and nickel matte converting. This process has been used for over 100 years because of its effectiveness in mixing of the molten bath, as well as its merits of the engineering simplicity. However, the mechanisms which · determine the blowing performance is poorly understood, and the design and operating conditions of the Peirce-Smith converter varies widely from plant to plant, such as by diameter, length, mouth angle, tuyere position and level of molten matte. Smelters have continuously made an effort to increase converter productivity, implying maximum tuyere blowing rate. Above a certain critical blowing rate, splash of molten matte from the converter mouth becomes unacceptable because of dangerous ejection and accretion buildup around the converter mouth, which results in interference with effective hood sealing. In fact, a 1993 converter survey[!] reported that splash was a major limiting factor for blowing rate and 54% of responding plants from around the world regard it as a limiting condition[2]. In order to increase tuyere blowing rate a study of the effect of various operating conditions on splashing behavior is expected."

Jan 1, 2000

By James W. Reeves

DuPont was the titanium metal pioneer who put the greatest effort into both R&D and commercial sponge and powder metallurgy production. This was concentrated in the period 1945 through 1963. The commercial results were development of the chloride process for TiCl4 using ilmenite, development and improvement of the Kroll process, development of a modified Hunter process to make titanium powder and commercial development of a direct powder process. The powder metallurgical process failed because of the inability to meet powder chloride specifications. All this work remained a trade secret until published in NMAB -392 by Mahla in 1983. There were other processes explored by DuPont, both improved sponge and powder processes. Much of this work has been continued by others but none, as of yet, resulting in new improved titanium metal capacity.

Jan 1, 2001

By Rod Samuels, Rupert Allen, Thomas Harper

"Viceroy Resource Corporation of Vancouver, B.C., has recently developed and brought into production the Brewery Creek Mine, an open-pit heap leach gold mine, located 55km east of Dawson City in Yukon, Canada. Mineable reserves are 15.2 million tonnes of ore grading 1.45 grams/tonne, containing 22 tonnes (707,315 oz) of gold. Ore processing employs the heap leach technology using run-of-mine ore. Highlights of 1996 activity included construction of a 158,000 m2 of leach pad, placing 1.9 million tonnes of ore at a grade of 1. 46 gpt to the leach pad, construction and successful commissioning of the ADR plant, and pouring of the first gold bar on November 15th.Permitting of this mine has drawn significant attention because of the innovated heap leach technology; although this technology has been proven in other jurisdictions, it has not been used at such extreme northern sites where winter temperatures routinely reach -45°C for extended periods.ABSTRACT ONLY"

Jan 1, 1997

By R. H. Lien

The Bureau of Mines, U. S. Department of the Interior, is investigating chemical and biological decontamination of complex wastewaters such as tailings pond water containing 280 ppm CN and 5 ppm Se as well as significant concentrations of arsenic, copper, iron, silver, and zinc. The most effective chemical procedure involves cyanide oxidation using hydrogen peroxide or sodium hypochlorite followed by selenium reduction using ferrous hydroxide. The effluent contains <l ppm CN and 20 ppb Se; concentrations of other major contaminants meet EPA drinking water standards. Preliminary research indicates that biological cyanide oxidation is possible even in highly alkaline solutions (pH 10.5) containing high cyanide concentrations; indigenous bacteria destroyed 85 pet of the cyanide. Exploratory research shows that other bacteria removed up to 79 pet of the selenium from chemically oxidized, low-cyanide water. These promising results may lead to a final processing scheme that involves a combination of chemical and biological techniques.

Jan 1, 1990

By Z. Smieszek, J. Botor, Z. Miczkowski, S. Sobierajski

"From 1978, the direct process for the smelting of chalcocite concentrates in a flash furnace by the Outokumpu method has been applied at the Glogów II copper smelter. The chemical composition of these concentrates make it necessary to control the process very strictly. In this paper, the method for controlling and measuring the main technological parameters of the copper production by flash smelting is being presented. It includes the determination of the chemical composition of the concentrate, its grain structure, the temperature of liquid products of the process, oxygen content in process gases, as well as lead concentration in copper and copper concentration in slag.The main process parameters are determined from the mass and energy balances. The relations between parameters, such as an effect of grain structure of a concentrate on oxygen and oil consumption, and dependence of chemical composition of a concentrate on capacity and products quality are discussed. 1. IntroductionThe Polish copper concentrates, as most concentrates occurring worldwide, contain from 18% to 30% Cu, and less sulphur (7-11%) and iron (2-5%). The main copper-bearing mineral contained in the concentrates is chalcocite, while bornite and chalcopyrite are present in smaller quantities. Moreover, the organic carbon (5-7.5%), arsenic (0.05-0.3%) and lead (1.2-3.0%) are also contained in the concentrates. The gangue consists mainly of silica, aluminosilicates, calcium carbonate and magnesium carbonate. Their proportions make the addition of slag-forming agents unnecessary.The composition of Polish concentrates, especially their low iron content, allows their application in the direct flash smelting process for blister copper production. Low sulphur content is the factor which determines the necessity of oxygen application in this process."

Jan 1, 1989

By Huimin Lu, Liyuan Zhao, Zhijiang Gao

The aluminum matrix composite reinforced by graphene was successfully fabricated using high pressure torsion (HPT). With only 0.5wt% graphene, the grain size was reduced to 100nm while that of pure Al was about 500nm. The hardness of the composite increased from the center (64HV) to the edge (120HV) of the sample. Moreover, the tensile strength of this composite reached 197MPa, while that of pure Al was 157MPa. The enhancement in mechanical properties was induced by grain refinement, load transfer from the matrix to the reinforcement and dislocations piled up at the grain boundaries.

Jan 1, 2015

By Sun Ying, Zhang Jing, Li Qiuju

A new process of enrichment Cu in molten copper slag under electric field is presented in this article. The experiments were carried out in the laboratory on a kilogram scale. The mobility of copper slag was improved by the technique of carbon reduction. The effects of temperature, electric field strength and intermittent feeding speed were investigated on Cu migration. The results showed that the best experimental conditions were the temperature at 1523K, electric field strength was 1.5V•cm-1 and feeding rates was 15 g•(10min)-1. The copper content of the slag decreased below 0.6wt%. The process was compared to the traditional electric furnace process of slag cleaning, there was reduced the energy consumption and heat loss, and also harmful gas emissions such as SO2 and CO2, accompanied by improved the efficiency of slag cleaning.

Jan 1, 2016

By R. D. Irwin, W. M. Mullins, E. A. Medina

"Various stability criteria are introduced and thermo-kinetic models for metallurgical processes are used as concrete examples for evaluation. Kinetic criteria for the process of dynamic recrystallization are proposed. These criteria are compared to the non-equilibrium thermodynamic approaches discussed in the literature. The application of macroscopic stability criteria to materials processing is then discussed.IntroductionThe mechanical behavior of metals at elevated temperature is very well predicted by any of several empirical constitutive relations. Typical is the power-law (or Swift's) form,Equationwhere r-is the stress, y is the strain and m, n , t0, y0 and Q are material constants. This form has been used with some success in the metals processing area [1]. In general, though, all of the empirical constitutive equations are static, failing to account for any dynamical properties of the system they seek to describe.The physics of warm deformation is qualitatively well understood. An example is power-law creep, where the dominant mechanism is assumed to be lattice diffusion limited climb of dislocations, which allows the strain-rate to be determined by the applied stress through"

Jan 1, 1997

By Jean Goldschmidt

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

Jan 1, 1995

By Sunil Jayasekera

This paper describes the results of a study carried out to examine the feasibility of electrolytic recovery of silver from cyanide leach liquor generated from a Western Australian silver mine tailings using a novel high mass transfer electrowinning cell. The proposed circuit involves heap leaching and electrowinning in a closed loop. The filter-press-like closed electrode arrangement of the cell allowed much improved mass transfer of metal ions to the cathode surface, making direct electrowinning of metals from dilute solutions feasible. The tests were conducted both in the laboratory and at large scale using a prototype with ~1.0 m2 cathode area. The results showed that the recovery of silver from as low as 250 mg L-1tenor was feasible. The silver deposit produced with the prototype cell was non-adherent and powdery and could be readily removed from the closed cell. A system was developed so that silver powder was discharged continuously during the run.

Jan 1, 2003

By Dongping Duan, Hongliang Han, Li Zhong, Siming Chen, E Zhou

In this study, physical, chemical and microscopic characteristics of Celestine were investigated firstly. Based on which, the thermodynamic analysis of Celestine reduction was discussed. And the experiments of Celestine carbon-containing pellets used in rotary hearth furnace process were studied. The results showed that it is feasible to deal with Celestine by rotary hearth furnace direct reduction process. When the temperature is 1200°C, C/O ratio is 0.8 and holding times is 20min, the conversion rate of SrSO4 in Celestine is above 95%, the utilization rate of Celestine is nearly 100%. This study can provide theoretical and technical basis on economical and rational use of Celestine.

Jan 1, 2016

By J. R. Donald

Electric arc furnace (EAF) dust, which can be considered as a by-product of the steel recycling process, contains significant quantities of recoverable zinc and iron, as well as hazardous elements such as cadmium, lead and chromium, which can be leached by ground water. The zinc in the EAF dust is found almost entirely in the form of either zinc oxide or zinc ferrite, the latter accounting for 20 to 50 percent of the total zinc. It is important that an efficient process be developed which renders the dust inert, while reclaiming the valuable metals to off-set processing costs. During the conventional carbothermic reduction processes, iron is formed, and this iron can participate in the reduction of the zinc oxide in zinc ferrite. In the present work, the reduction of the zinc oxide in zinc ferrite by iron according to the following reaction: ZnO-Fe2O3(s,s) + 2 Fe(s) = Zn(g) + 4 FeO(s) was studied in an argon atmosphere using a thennogravimetric technique. First, a thermodynamic analysis was performed using the F*A*C*T computational system. Then, the effects of briquette aspect ratio (lid), temperature, zinc ferrite particle size, amount of iron added, as well as additions such as lime, sodium chloride, and calcium fluoride were investigated. It was found that, initially, the reaction was chemically controlled with an activation energy of 178.1 kJ/mol. Then, after a product layer had formed on the outer surface of the briquette, the reaction was restricted by the diffusion of zinc gas away from the reaction interface. The parabolic rate law was fitted to the experimental data, and the parabolic rate constant was found to be: = -6.2275 + 0.0054 T (K)

Jan 1, 1995

By P. K. Jimack, C. E. Goodyer, A. M. Mullis, P. C. Bollada

"We review the application of advanced numerical techniques such as adaptive mesh refmement, implicit time-stepping, multigrid solvers and massively parallel implementations as a route to obtaining solutions to the 3-dimensional phase-field problem with a domain size and interface resolution previously possible only in 2-dimensions. Using such techniques it is shown that such models are tractable even as the interface width approaches the solute capillary length.IntroductionMulti-scale modelling impinges upon many areas of science, engineering and technology where the interplay between processes occurring on disparate length and/or timescales can affect the properties of systems in a complex, and sometimes unforeseen, manner. One such is the processing of materials where interactions at the atomic scale, through the nano- and microstructural scale can have a profound affect on the macro-scale response of engineering components. Here we focus on one such problem, the crystallisation of alloy melts, to illustrate how a range of advanced numerical techniques make the modelling of such systems tractable.The modelling of solidification structures, in particular the growth of dendritic crystals, is a subject of intense and enduring interest within the scientific community, both because dendrites are a prime example of spontaneous pattern formation and they have a pervasive influence on the engineering properties of metals. For alloy systems, which form the vast majority of engineering materials, solidification involves the rejection of both solute and latent heat from the growing solid, forming a coupled diffusion problem in which both the chemical and thermal diffusion equations should be solved. The multi-scale nature of this problem arises from the disparity between the thermal and solutal diffusivities for most liquid metals, which are typically 10-5 m2 s-1 and 10-9 m2 s-1 respectively. The ratio of these two, referred to as the Lewis number (Le =Dia), is therefore typically of the order 10,000 and gives a measure of the multi-scale nature of the problem. In fact, in many cases the thermal diffusivity is so much larger than its solutal counterpart that thermal diffusion is considered instantaneous, wherein the system can be approximated as isothermal such that the multi-scale calculation does not need to be performed. This is certainly a reasonable approach in most conventional castings. However, there is a class of solidification problem in which this approach is far from satisfactory, namely Rapid Solidification (RS). The application of isothermal phase-field models in such situations are highly likely to produce spurious results or to fail totally, particularly for temperatures below To (the temperature at which the free energies of the solid and liquid phases are equal at the concentration of the bulk alloy), wherein partitionless solidification may occur."

Jan 1, 2013

By Truan-Sheng Lui, Li-Hui Chen, Hao-Wen Hsueh, Fei-Yi Hung

"Since Ag wires have similar hardness and bonding properties to Au wires, they can be applied in some pads. In the present study, the annealing effect (at 225°C~275°C for 30min) on the tensile mechanical properties of silver wires with f=23µm was investigated. In addition, the micro-structural characteristics and the mechanical properties before and after an electric flame-off (EFO) process were also studied. Experimental results indicate that with annealing temperatures of more than 250°C, the silver wires possessed a fully annealed structure, the tensile strength and the hardness decreased, and the elongation was raised significantly. Under the thermal effect of EFO, the necks of the Ag balls underwent recrystallization and grain growth was induced, and the annealed Ag wires had a shorter zone of HAZ (220µm). The bonding strength and the neck-strength of the Ag wires were more than 7gf and possessed excellent bonding properties.IntroductionThermosonic ball bonding is one of the preferred processes for electronic packaging to connect a semiconductor chip and a lead frame by a thin metal wire. At present, gold wire and copper wire are the preferred interconnect materials to bond with the aluminum metallized wafer pads [1, 2]. Since gold is expensive and the reliability of copper is poorer [3], the study of silver wire has attracted a lot of attention already. In addition, the inherent properties of high ductility and low hardness of silver as well as its workability effectiveness compared to gold, have made it a preferred alternative .[4, 5]"

Jan 1, 2012

By K. D. Peaslee, V. L. Richards, C. H. Rawlins, S. N. Lekakh

"Steel-making processes generate carbon dioxide air emissions and a slag co-product. The aim of this project was to develop a functional sequestration system using steelmaking slag to permanently capture carbon dioxide emitted in steelmaking offgas. A possible parallel benefit of this process would be rapid chemical stabilization of the slag minerals with reducing swelling or leaching.This paper summarizes the original results of the project, including mineralogical and structural features of carbon sequestration with steel making slag, mathematical modeling of reaction phenomena using a modified shrinking core model, METSIM modeling of several possible industrial applications, a thermo-gravimetrical study of the reaction between slags and different gases, and design and testing for a lab scale apparatus consisted of two reactors.1. IntroductionThe U.S. produces 9-14 Mt of steelmaking slag annually, which represents approximately 10-15 wt. % of crude steel output.1,2 Primary uses for steelmaking slag include high quality mineral aggregate, Portland cement, unconfined fill, soil conditioning, and pH neutralization of abandoned mine drainage.3,4 The key factor prescribing slag use is the alkaline-earth metal (e.g. Ca and Mg) oxides content, which contribute to overall basicity and cementitious strength. However, as-produced steelmaking slag is chemically unstable. Calcium and magnesium oxides readily form hydroxides and carbonates through reaction with atmospheric gases. Both hydroxide and carbonate formation produce substantial mechanical swelling leading to heave failure in confined construction applications, thus many states dictate stockpile aging for 3-6 months prior to commercial use.5,6 Sequestration of carbon dioxide is a natural corollary to forced carbonation. The conversion of CaO/MgO to carbonates serves both to stabilize the slag, and permanently capture and store the CO2."

Jan 1, 2008

By Hyun Kyu Shin, Byeong Deok Lee, Young Eun Lee

The reduction of Mn oxides at pre-smelting steps is an integral part of smelting processes for Mn alloys, and an understanding of its reaction mechanism is expected to contribute to the improvement of processing efficiency for Mn alloys smelting. The phase diagram shows that five Mn carbides are operative in the Mn-C system. Although they are expected to participate in the reduction of Mn oxides, no specific information is available yet to clarify their roles in presmelting carbothermic reaction of Mn oxides. Experiments with composite pellets prepared with Mn oxides and graphite powders show that Mn3O4 is reduced initially to MnO at about 1130oC and, subsequently, to Mn7C3 carbide as temperature increases further. At 1331oC, Mn7C3 carbide dissociates to Mn alloy and carbon. The degree of reducing reaction increases with increasing carbon balance in composite pellets and increasing temperatures.

Jan 1, 2014

By R. E. Johnson

The No. 3 reverberatory furnace at Phelps Dodge. Corporation&apos;s Morenci, Arizona copper smelter first received oxygen from a new oxygen plant during October 1982 and began operation with oxygen-fuel and oxygen sprinkle smelting burners which burn concentrate with oxygen. The furnace was completely converted to roof-mounted oxygen-fuel firing in October 1982. All conventional air-fuel bridge wall burners were extinguished at that time. The novel arch-mounted oxygen sprinkle smelting system began continuous operation April 1983. Since startup, unit fuel requirements decreased and furnace throughput significantly increased. Furnace off gas SO2 strength increased from an average of 1.5% SO2 to an average of 20% using only oxy-fuel burners. Oxygen sprinkle burner operation also has given excellent results, with the furnace off gas strength increasing to 35%-60% S02. There has been a reduction in overall arch temperatures, an increase in matte and slag temperatures, and a lowering of furnace bottom buildup with oxygen smelting. Furnace off gas is blended with converter off gas and treated in a sulfuric acid plant.

Jan 1, 1983

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

"The Chinese bismuth production accounts for more than 80% all over the world in 2011. The main raw materials of bismuth smelting are bismuth concentrate and by-products of Cu or Pb smelting process. Many traditional methods of bismuth smelting in china was reviewed in this paper, such as reverberating furnace smelting, blast furnace smelting, fire-refining, ferric chloride leaching-hydrolysis, slurry electrolysis, and so on. But all the traditional pyrometallurgy or hydrometallurgy process have such shortages of low recovery, poor environment, and high cost. Therefore new technologies are introduced into the smelting process of bismuth concentrate, such as low-temperature alkaline smelting and side-blown bath smelting with oxygen-enrichment. These technologies have got great progress on energy saving, emission reduction, and friendly environment. Finally the development direction of new technology on bismuth smelting was prospected.IntroductionAs a green metal, bismuth has a wider applications, just extending from the traditional medicine, metallurgical-chemical engineering, low-melting alloys, solders, catalyst, and electronics to cosmetics, flame retardant, storage battery, semiconductor, supper conductor and nuclear energy etc[1,2,3,4,5,6,7]. This will increase the production of bismuth and promote the development and progress of bismuth smelting technology. At present, The major bismuth-product countries are China, Mexico, Peru, KZ, Bolivia and Canada etc, and China are dominating. A survey from the USGS[8] showed that Chinese bismuth production were 12,500 tonnes and got 80% of the world's in 2011. Thus the technology of Chinese bismuth smelting have a great representativeness."

Jan 1, 2013