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Sm-Co alloy is a kind of magnetic material with high power and has been applied in modern industry widely. In this study, the wet chemical co-precipitation was developed for synthesis of the Sm-Co alloy oxide precursor. The thermodynamic analysis of the studied system was done to clarify the solution behavior theoretically based on the thermodynamic equilibrium and simultaneous equilibrium. Then, the experiments were done to address the various effects on the wet chemical process, including solution pH, reactant concentration, dispersant, reaction temperature and time, etc. It is found that by precise control of the process, the Sm-Co alloy oxide precursor was synthesized with fine crystallization and special size & size distribution.

Jan 1, 2005

By Patricia Martínez Nicolás

Nickel and ferronickel are some of the major components in the production of special alloys; however, the energy consumption for their production greatly increases their price. A cheaper option could be to use NiO and a reducing agent. This work presents experimental and theoretical analysis to estimate the effect of slag basicity and amount of reducing agents on the NiO reduction from the slag which interacted with molten steel at 1600 °C in an EAF. The slag system contained CaO, SiO2, CaF2 and NiO together with a reducing agent, ferrosilicon or carbon. The NiO content in the slag was 25 mass%. The amounts of the reducing agents (Si and C) were 1 to 4 times the stoichiometric mass to reduce NiO. The CaO/SiO2 ratio was 1.5 and 2.5. The kinetics of the process was very fast since after few minutes the maximum nickel yield was obtained. The slag basicity had a negligible effect on the reduction of NiO.

Jan 1, 2006

By P. N. Anyalebechi

Keywords: Aluminum alloy 3004, Solidification rate, Homogenization, Second phase particles The effects of the fineness of as-solidified cast microstructure and temperature on the response of aluminum alloy 3004 to homogenization heat treatment (a.k.a. preheat) have been investigated. The study was conducted at 538oC and 595oC on directionally solidified laboratory-size ingots with a range of solidification rate of 0.10oC/s to 29.4oC/s. Optical and electron microscopy, quantitative image analysis, electrical conductivity, and electron probe microanalysis were used to quantify the effects of the homogenization heat treatment on the microstructure of aluminum alloy 3004. In general, increase in fineness of as-cast microstructure and homogenization temperature enhances the a-transformation reaction, dissolution of Mg2Si, elimination of dendritic microsegregation, and dispersoid formation. The homogenization heat treatment reduces the average size of second phase particles in castings solidified at <1oC/s. However, in castings solidified at above 1oC /s, homogenization causes the coarsening of the second phase particles. Mn in solid solution is independent of homogenization heat treatment temperature.

Jan 1, 2005

By Michael P. Sudbury

Non-ferrous slags are granulated and stockpiled as an alternative to pit cooling or transporting molten slag to a dump. The chemical composition of such slag is determined by the pyrometallurgical process in which it is produced, while the size distribution is set by safety concerns or a desire to reduce wear of pumps, pipelines and other equipment. Relatively few operations give consideration to the effect of granulation conditions on other properties of the granulate as the material is typically accumulated on the smelter site. It is becoming recognized that slag has many potential commercial uses and carries much of the energy applied to the smelting operation. This paper outlines the findings of extensive work to identify uses for granulated non-ferrous slag, the importance of preparation conditions on the properties, impediments to more extensive use of granulated slag, the real costs of slag stockpiling and the opportunities for further productive research.

Jan 1, 2006

By Holger Cordes

X-ray diffraction has long been used for qualitative and quantitative mineral analysis but Rietveld data analysis is still an under utilized method for mineral exploration and processing applications. In this full-profile approach the structural parameters of each mineral phase, together with experimental parameters, are refined by least-squares methods to minimize the difference between observed and calculated diffraction patterns. The result is a standard-less, quantitative analysis of the mineral abundance in the sample that is more accurate and considerably faster compared to traditional methods. The TOPAS software package combines a user-friendly interface with a unique approach to resolve overlapping peaks. Automated analysis options are also available and significantly reduce analysis time for routine samples. Several examples on a wide range of naturally occurring rock types are shown that illustrate the capabilities and limitations of the method. The examples include several options for the quantification of amorphous constituents like volcanic glasses.

Jan 1, 2006

By Murat Baydogan

Effect of retrogression and reaging treatment on hardness and stress corrosion cracking resistance of 7075 aluminum alloy was investigated. As received 7075 alloys in T6 temper condition were retrogressed at 170, 220, 240 and 380°C for different durations between 15 s and 60 min. Subsequent reaging was made at the T6 aging condition. Treated materials exhibited higher hardness and better stress corrosion cracking resistance than T6 temper in a wide range of retrogression temperature and time. The highest hardness was obtained after retrogression at 170°C for 210 s followed by reaging, corresponding to 20% hardness improvement. Improvement in stress corrosion cracking resistance of the alloy by as much as 85% was also observed. In this paper, improvements in hardness and stress corrosion cracking resistance are discussed on the basis of the microstructural changes during retrogression and reaging treatment.

Jan 1, 2006

By Christoph Zschiesche

Managing complex material streams within a lead smelting/reduction process has a long history at Aurubis. After modernization of the secondary lead smelter in 1991, Aurubis operates an electric furnace and a Peirce Smith converter to process complex secondary materials. This process links the copper and the lead metallurgy allowing Aurubis to properly combine primary and secondary process lines to optimize the processing of complex raw materials and smelter intermediates. However, combination of copper and lead metallurgy processing requires a continuous evaluation as raw material quality and composition varies. This paper describes Aurubis lead smelter processing and provides some fundamental considerations to optimize the lead processing, in particular with aspects related to speiss formation

By Stéphane Bourg

The SCRREEN project gathers more than 50 European initiatives, associations, organisations or independent experts working on Critical Raw Materials (CRM) into a long-lasting network including stakeholders, public authorities, and civil society representatives. SCRREEN contributes to improve the CRM strategy in Europe by (i) mapping primary and secondary resources and substitutes of CRMs, (ii) estimating the expected demand of various CRMs in the future and identifying major trends, (iii) providing policy and technology recommendations for actions improving the production and the potential substitution of CRM, (iv) addressing specific waste electrical and electronic equipment (WEEE) and other End-of-Life (EoL) product issues related to their mapping and treatment standardization, and (vi) identifying the knowledge gathered over previous years and making the data accessible to those beyond the project. As a first step, SCRREEN worked at providing stakeholders with a comprehensive analysis of the current use of the CRM, the mapping of potential primary and secondary resources, and identification of the key technologies used in their production. Substitution profiles, analysis of European business and policy issues pertinent to CRMs, and an identification of the standards, policies, and regulatory frameworks concerning these CRM was also completed. In a second step, to be conducted between mid-2018 and mid-2019, SCRREEN will provide guidance for improving the CRM market in Europe by identifying opportunities from research, development, and innovation (R&D&I) that could reduce the supply and/or economic risks around the most relevant CRM for Europe.

By Yufeng Guo

Mineralogy and physico-chemical characteristics of a nickel hydrometallurgical residue and recovery of iron-bearing minerals by flocculation-magnetic separation were studied. The results show that the nickel residue is super-fine and fraction less than 0.045mm reaches 85.4%. Ferrous minerals are chiefly magnetite and ferruginous glass. Magnetite accounts for 31.7% and exists as free magnetite. Ferruginous glass is of multicomponent amorphous substances with low-iron grade but strong magnetism, and accounts for 39.9% of total iron minerals. Addition of flocculants increases granularity and magnetic force of fine iron-bearing particles and improves iron grade and recovery. The tests with flocculation separation show that a concentrate assaying 56.68% Fe with 81.72% recovery was obtained in a magnetic tube. A concentrate with 56.92% iron grade and 67.96% recovery was obtained by flocculation-magnetic separation with a magnetic cylinder.

Jan 1, 2006

By David Arana

The use of gas-water dispersion of a molten material flow onto a vibrating surface is developed as a process to minimize water pumping requirements, minimize the risks of explosions, and minimize the post solidification dewatering and fines handling equipment requirements. The process uses existing vibration transport technologies and common plant utilities. Plant trials using the smaller footprint and the progressive molten particle cooling time have yielded encouraging results. The results are analyzed and reported.

Jan 1, 2006

By Luciano R. G. Santos

Keywords: biosorption, cadmium, copper, biomass, spent zeolite. The majority of the industrial activities produce some kind of solid wastes. In this work two industrial residues (spent zeolite and wood sawdust) were chemically modified to increase their heavy metals sorption capacities. Manilkara longifolia (a Brazilian plant known as parajú) sawdust was first treated with NaOH and modified with different citric acid concentrations (0.6-1.2 mol/L) at 120°C, for 90 min. Infrared spectroscopy confirmed the presence of carboxylate groups in the wood structure as result of their mixing. Similarly, spent zeolites were also submitted to a chemical treatment (NaOH) to remove carbon deposited during oil cracking and to recover its sorption capacity. Batch experiments carried out at ambient temperature showed that both materials present sorption capacity for copper and cadmium comparable to weak acid ion exchange resins. A maximum of 78 mg-Cd/g and 59.7 mg-Cu/g as well as 29.9 mg-Cd/g and 14.6 mg-Cu/g were observed for the sawdust and the zeolite, respectively. The results were modeled according to the Freundlich and Langmuir equilibrium isotherms and compared with results of other studies.

Jan 1, 2005

By Xue Wang, Callie Babbitt, Chelsea Bailey, Matt Ganter, Gabrielle Gaustad, Brian Landi

"Current trends, motivated by fossil fuel dependence and unprecedented greenhouse gas (GHG) emissions, show lithium-ion batteries (LIBs) emerging as a competitive energy storage technology due to higher power and energy densities compared to Pb-acid and Ni-metal hydride chemistries. These trends may be of concern, however, as environmental impacts are not well understood for either the LIB itself, or for the nanoparticles consumed or released during the battery's production, use, or end-of-life. This study combines economic modeling, dynamic material flow analysis, and fundamental material characterization methods in order to quantify some of the economic and environmental trade-offs for LIBs at their end-of-life. As expected, results show that as chemistries transition from Li-Co based cathodes to Li based Fe, Mn, and S cathodes, LIB recovery value correlates to the value of the raw materials used. These initial results aim to inform collection policies being proposed currently as well as enable future deployment of novel recycling techniques.IntroductionGlobal fossil fuel dependence and unprecedented GHG emissions have led to increasing attention on energy alternatives, for both electricity production and personal transportation. However, development of renewable energy systems is contingent on concurrent technological development of energy storage systems, primarily batteries used for power grid load-leveling, renewable energy storage, and hybrid and battery electric vehicles. In this sector, lithium-ion batteries (LIBs) are emerging as a competitive technology due to higher power and energy densities compared to lead-acid and nickelmetal hydride chemistries[!]. LIBs represent close to 20% of the total rechargeable battery market and 75% of the portable rechargeable battery market, which is the fastest growing segment of the rechargeable battery market, with a 20% global growth in 2008 [2].This surge in production ofLIBs indicates a looming waste problem; total waste from Li-ion batteries has likely grown substantially from the 500 metric tons estimated in 2003 [3]. Figure IA shows the substantial increase in world-wide lithium production that has occurred in the last several decades with batteries making up the largest share of applications (Figure lB). California and New York state legislators have attempted to proactively address this looming waste by issuing diposal bans on rechargeable batteries in their states[4, 5]. However, quantification of the costs involved in collection, transportation, and processing of these materials has not been examined in depth."

Jan 1, 2012

By Mitchell L. Spencer, Viswanathan Panchanathan

"Bonded magnets are important category in permanent magnets. They are made by one of the following processes: compression bonding, injection molding, extrusion, calendering. An overview of the various bonded magnet processes and properties of products made with different magnet materials along with their applications are discussed. The main emphasis will be on the use of bonded NdFeB and ferrite magnets.IntroductionBonded magnets are a major growth area in permanent magnets. Bonded magnets are made by any one of the following processes: Compression bonding; Injection Molding; Extrusion and Calendering [1,2]. Compression and injection molded magnets are rigid magnets. Materials used in calendering process produce flexible magnets. Only the extrusion process makes both rigid and flexible magnets. The binders used for the bonded magnets vary depending on the processes. Thermoset, thermo-plastic and elastomeric binders are respectively used in compression, injection and the calendering process. Extrusion molding uses elastomers or thermo-plastic materials. The most co=on magnetic materials, Ferrite, SmCo, Alnico and NdFeB can be used in any of the above processes either alone or in combination as hybrid magnets. Another material that has been developed for co=ercial application is SmFeN. Making the material has been challenging and it is being used in niche market applications in limited quantitiesIn the extrusion process, a highly loaded compound is used to produce strip or sheet and is continuously extruded through a die. In calendering the granulated compound is rolled to produce a continuous wide sheet. In the compression bonding process a uniaxial pressing force is used. These magnets have higher loading compared to injection molded magnets. In injection molding the material is forced into a mold cavity and has lower loading compared to compression molded magnets [2,3]. Most of the flexible magnets are made using extrusion and calendering processes and the most co=on magnet material is inexpensive ferrite. Flexible magnets have been made using rare earth materials, but on a very limited basis.The major advantages of magnets processed by extrusion and calendering are as follows: inexpensive tooling, automation; practically any 2D geometry; fast production rates; no chipping or breaking; a wide range of properties; on-line magnetization; easy to convert (e.g. cut, punch or shape).Compression bonded magnets are inexpensive to manufacture. They have higher magnetic properties compared to injection molded magnets; however lower than their sintered counterparts. The magnet shape is restricted to simple geometries and they require careful handling. Their isotropic nature allows complex magnetizing patterns."

Jan 1, 2013

By Donald Voit

"The reaction between zirconia/zircon, coke, and chlorine involves a slow reaction between the coke and the zirconia/zircon and a fast reaction with chlorine. Because of the fast chlorine reaction, the reaction rate for zirconia/zircon is nearly independent of chlorine concentration for most conditions. The reaction between zirconia/zircon and coke is particle size controlled and related to the degree of physical contact between the zirconia/zircon and the coke. Since particle-particle contact is critical, compaction of finely ground coke and zirconia/zircon produces the highest reaction rates. Uncompacted, coarse coke and zirconia/zircon has the slowest reaction behavior with static bed tests.SummaryZirconia reacts with chlorine in the presence of carbon to form zirconium tetrachloride, carbon monoxide, and carbon dioxide. A similar reaction occurs with zirconium silicate with the additional formation of silicon tetrachloride. The reaction rate depends primarily on temperature and the intimacy of contact between the zirconia and the coke. The reaction is multi-stepped with a slow reaction between coke and zirconia to form an intermediate that reacts rapidly with chlorine, causing the order of the reaction for chlorine to be near zero. Chlorination rates in the range of 1 µmole/hr/cm2 are seen for fluid bed reactors. Plug flow, and static bed reactors have reaction rates of the order of 1 mmole/hr/cm2, where the area is based on the zircon surface area in plug flow and fluid bed reactors and the boat cross sectional area in a static bed. Chlorination rates measured in zirconia/coke briquettes are higher with rates as high as 400 mmole/hr/cm2 reported. High chlorine diffusion resistance, not accounted for in the analysis of experimental results, has led to a lot of confusion in the literature interpretation of chlorination data.In general coke and zirconia/zircon particle size, coke and zirconia/zircon intimacy, coke to zirconia/zircon ratio, chlorine concentration, and temperature are important variables for chlorination. Decreasing the coke and zirconia/zircon particle size generally increase the reaction rate. The coke to zirconia/zircon ratio affects the reaction in a more complex way. Increasing the chlorine concentration generally increases the reaction rate, but the effect appears to be more related to the concentration dependency of diffusion than to its role in the kinetics. The reaction rate increases with temperature but the exact behavior is complicated by temperature effects on diffusion."

Jan 1, 2011

By Jürgen Antrekowitsch, Thomas Griessacher

"Heavy metal containing residues are typically hazardous wastes because on the one hand, a deposition gets more and more complicated and on the other hand, the large amounts of metals like Zn, Cu, Fe and Pb represent a significant value. Thus, a post-treatment of these materials with the recovery/recycling of the metals and stabilization of the waste is not only ecological but often also economical. The therefore typically applied recycling processes utilize pyrometallurgical steps, where carbon or carbon monoxide from fossil coal and coke is used as a reducing agent, which results in large amounts of CO2 emissions. An alternative option is the application of a hydrogen-rich gas emitted in biomass utilization processes as a carbon-neutral reducing agent. Investigations in a retort process which were done at different temperatures and times showed excellent results concerning the achievable reduction rates and final contents of the heavy metals for various residues.IntroductionNowadays heavy metal containing residues like electric arc furnace dust (EAFD), dust from cupola furnaces, waelz slag, etc. are declared as hazardous wastes in a growing number of countries due to the leachability of the heavy metals in these residues. For that reason it is no longer possible to landfill these materials or use them for road construction or disposal works. Some land filling activities, carried out until now, have only been realizable because of some process modifications or cost intensive post-treatment steps of these residues. But the disposal capacities for such materials are decreasing, therefore increasing the prices. The second point for the growing disposal limitations is the stringent environmental legislations and regulations, which restrict the number and amounts of materials which can be dumped [1 – 5].From the other point of view these heavy metal containing residues usually have high contents of zinc, lead, iron, etc., which represent a significant value and therefore a big potential to recover these metals. This is why in recent years the number of recycling processes and the amount of recycled heavy metal containing residues have continuously increased. These recycling processes have the target to recover the valuable metals from the residual materials in the form of a saleable product as well as the stabilization of the slag produced in these processes [5, 6]."

Jan 1, 2011

By Elli Nurminen

In this work the thermodynamics of the metallic sulphate decomposition reactions were studied through thermodynamical calculations and thermogravimetric methods. The decomposition temperatures and mechanisms were determined for cupric sulphate, ferric sulphate and also for industrial flue dust from a copper flash smelting process. The aim was to determine the thermodynamic conditions for sulphate decomposition and to estimate whether the reactions are kinetically likely to take place in the flash smelting process heat recovery equipment. The information is essential in CFD-modelling of the reactions taking place in the boiler and for optimising the process.

Jan 1, 2006

By F. Z. Utyashev

The present work considers the essence of fragmentation: on the level of a simple model as a material response to the curvature accumulated by it at large deformations. It is on this basis that the correlation between curvature and fragment sizes is determined. It is shown that at deformation the area of curvature center inevitably changes. It is revealed that a specific value of variation of center surface area, i.e. ^As parameter, is numerically equal to the value of curvature acquired by a material. Minimum sizes of fragments and grains depending on ^As have been estimated, and the dependence of this parameter on strain has been established. Besides, the present paper considers the effects exerted by curvature center geometry, material distortion, directions of deformation and thermal warming up in the localization zones on structure refinement when various techniques are applied.

Jan 1, 2006

By Eun-young Kim

Electrogenerated chlorine leaching of waste printed circuit boards was investigated in hydrochloric acid solutions. The pulverized printed circuit board contained about 37.6% of metal component, in which copper was about 83.6%. The leaching rate of copper was greatly affected by current density and agitation speed. The leaching of copper up to 98% was achieved at 20 mA/cm2, 50?, 180 minutes, and 600 rpm in 1M HCl solution. Increasing agitation and lowering current density enhanced utilization efficiency of electrogenerated chlorine. Leaching of copper was suppressed at initial stage, while the minor metal elements, such as aluminum, lead, and tin, were dominantly leached out.

Jan 1, 2006

By Hirokazu Narita

Keywords: solvent extraction, precious metals, thiodiglycolamide, rapid separation, hydrochloric acid The solvent extraction of some precious metals (Pd(II), Pt(IV), Rh(III) and Au(III)) and base metals (Fe(III), Cu(II) and Zn(II)) in a hydrochloric acid solution was carried out using N,N&apos;-dimethyl-N,N&apos;-dioctyl-thiodiglycolamide (MOTDA) dissolved in the mixed solution of 80 vol-% dodecane and 20 vol-% 2-ethylhexanol. The extraction percentages of Pd(II) and Au(III) in the 0.01 M MOTDA-1.0 M HCl solution system are 99.6% and 71.8%, respectively. In contrast, the other metal ions are hardly extracted under the studied conditions. The Au(III) and Pd(II) extracted in the organic phase are easily back-extracted with a 1.0 M thiourea/1.0 M HCl solution. A comparison with the conventional extractant for the Pd(II) separation, di-n-hexyl sulfide (DHS), revealed that the extraction rate of Pd(II) with MOTDA is much greater than that with DHS. The extraction percentage reached over 99% in less than a 2 min contact time. However, in the DHS-Pd(II) system, it takes about 240 min to achieve the extraction equilibrium. Furthermore, MOTDA can quantitatively extract Pd(II) up to half the molar amount of MOTDA. Therefore, MOTDA is a promising extractant for Pd(II) from the HCl solution after the removal of Au(III).

Jan 1, 2005

By Yuanbo Zhang

Zinc leach residues produced by hydrometallurgical zinc plants contain many valuable elements (zinc, iron, lead, gallium, indium silver, etc), while they have not been utilized effectively hitherto. In this paper, a new process of flotation-reduction roasting-magnetic separation to recover these valuable elements from zinc leach residues is developed on a basis of mineralogy investigations of them. The results show that silver concentrate with grade of 4321.6 g/t and recovery of 80.69% have been obtained, using 1750 g/t Na2S as conditioner, 750 g/t ammonium dibutyl dithiophosphate and SN-9 (assistant collector) as combined collector and 100 g/t terpenic oil as frother, if zinc leach residues with 523 g/t silver are floated at pH = 5.0. When the flotation tailings are subjected to reduction roasting at 1100? for 2 h, the volatilizations of zinc, lead and indium are over 96%. After roasted products are treated by wet-grinding and magnetic separation, the grade of gallium and gallium in the concentrates achieved respectively reaches 1805 g/t and 1536g/t, and the recovery of them is high to 94.67% and 93.20%, respectively.

Jan 1, 2006