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By S. A. Shuey

The present industrial practice used to separate aqueous cobalt from nickel is multistage solvent extraction processing. This paper describes a different but simpler treatment technology. The proposed technology has been applied to cobalt/nickel hydroxide intermediate solids produced from the treatment of Electrochemical Machining (ECM) waste sludge, The process consists of dissolving the cobalt/nickel hydroxides in basic cyanide solutions. Cobalt and nickel form aqueous .solution metal cyanide complexes. Nickel can be selectively precipitated from the solution as a nickellic hydroxide solid. Cobalt can be recovered from the leach solution by precipitation of a cobaltous/cobaltic cyanide double salt. The double salt product can then be subsequently treated to produce an appropriate cobalt product. The process chemistry, proposed fiowsheet and preliminary reagent costs are presented and discussed.

Jan 1, 1998

By Zhihao Yue, Honglie Shen, Yahui Teng, Ye Jiang

"In this paper, manganous nitrate [Mn(NO3)z] was used to assist the etching of silicon wafer in hydrofluoric acid (HF) for the antireflective application, and alumina (Al2O3) layer was deposited on the surface of the etched sample by atomic layer deposition method for further antireflection. The surface morphological and compositional studies of these samples were performed by scanning electron microscopy attached with an energy-dispersive X-ray spectrometer. The surface reflectance measurements were carried out using UV-Vis-NIR spectrophotometer. Binary structures of pyramids and nanopores were obtained by etching the alkaline textured monocrystalline silicon wafer in HF and Mn(NO3)z mixed solution for not more than 15 min. But excessive increase of etching time of up to 30 min resulted in the whole destruction of pyramids. The average reflectances of the 5-min-etched sample before and after being coated with 75-nm-thick Al2O3 layer are 4.62% and 3.47% in the range of 200-1000 nm, respectively.1. IntroductionAs we know, the reflectance of silicon wafer after being sliced is so high that the maximal photoelectric conversion efficiency of silicon based solar cells is limited. Therefore, alkaline texturization process was used for silicon solar cell in industrial production. But the reflectance of this alkaline textured wafer is still greater than 10% and this process can only be used for monocrystalline silicon solar cell."

Jan 1, 2013

By R. Cavanagh

Studies relating to the fixation of sulfur by reaction of 4 to 8 mm diameter cylinders of calcined limestone or dolomite with high strength sulfur dioxide in the temperature range 880°C to 1020°C were undertaken. Dolomites are far superior in sulfate capacity and reactivity than dense limestones even at high strength SO2. The sulfation reaction was first order with respect to SO2 concentration below 100 percent. Zero reaction rate at 100 percent SO2 concentration indicates that sulfate was the exclusive reaction product and that sulfite had no role in the reaction. At relatively low SO2 concentrations gaseous diffusion through the reaction product layer has a marked effect on the rate. As SO2 concentrations were increased up to 100 percent more complex rate controlling mechanisms unfold. By sectioning partially reacted dolomitic limestone pellets a moving interface was observed. Reaction ceased because of pore plugging for dense non-porous limestones at 30% conversion. With dolomitic material virtually complete sulfation of the calcium was observed. S.E.M. analysis showed that the average atom ratio Ca:S was 1.01, thus supporting the argument that little if any of the magnesium was sulfated.

Jan 1, 1996

By M. H. Staia

A Venezuelan ilmenite concentrate has been chlorinated at a temperature of 700" C by carbon tetrachloride. In the experimental rig, built at laboratory level, the direct chlorination process yielded a TiCI, recovery of approximately 85% after 280 minutes processing. The partial pressure of carbon tetrachloride was nearly atmospheric (0.94 atm). Product vapors from the reactor were fractionally condensed in a condenser which was maintained at a temperature of 250°C meanwhile TiCl, vapors were condensed in refrigerated coils at a temperature of -20°C. The concentrate used in this investigation was obtained by applying gravitational and magnetic concentration methods to the black sands. The experimental results have shown the need to asses the influence of the weight ratio of ilmenite to carbon tetrachloride on the resultant products. The equilibrium of the heterogeneous system has been calculated taking into account the initial experimental conditions.

Jan 1, 1995

By Srinath Viswanathan, Zhijing Zhang, Ramana G. Reddy

"The viscosity measurements were carried out on melts of 380 aluminum alloy containing 20 volume % SiC particulates under various shear rates at different temperatures using a Brookfield viscometer. Results showed that viscosities of the melts increased with decreasing temperature and decreased with increasing shear rate. These results were compared with those of 356 alloy and it was found that the temperature had a more significant effect on viscosity of 356 alloy than that of 380 alloy containing SiC particulates. Based on the present experimental data an empirical viscosity model, which considers the effects of both solid fractions in the melt and shear rate, is proposed.IntroductionDiscontinuously reinforced metal matrix composites materials (MMCs) such as aluminum alloy containing SiC particulates have considerable potential for applications in the automotive industry because of their superior stiffness, higher specific mechanical properties, better dimensional stability and strength retention at elevated temperatures when compared to their monolithic counterparts. They have a great advantage in the specificity of their properties, meaning that specific materials can be engineered for specific applications. With such freedom of design, materials engineers have to accumulate a very large database of mechanical properties. Among these properties, the viscosity of alloy slurries is very important for producing, casting and forming process of metal matrix composites materials because viscosity has a decisive influence on fluid flow. The understanding of the rheological behavior of alloy slurries is necessary for these materials to become economic reality. Therefore, a study was carried out to measure the viscosities of 380 aluminum alloy containing 20 volume % SiC particulates under various shear rates and temperatures. In addition, a viscosity model representing the primary features of the alloy slurries was developed."

Jan 1, 1999

By Bowen Li, Matthew D. Andriese, Jiann-Yang Hwang, Zhiwei Peng

"Magnetic iron sulfide ore particles heat rapidly by microwave (MW) irradiation generating plasma during oxidation of surfaces. The high temperatures produced by the exothermic event decompose local portions of samples forming a differentiated flux of partially melted silicate (si-mt) with entrained metal-sulfide (sul-mt) droplets. The si-mt forms crystals of olivine (01) in Ca-rich pyroxene (Cpx) melt that resorbs a portion of iron sulfide (Po). The immiscible sul-mt droplets of (Fe,Ni,Cu)1-xS contain magnetic subsolidus Ni-pyrrhotite (Ni-Po) with Cr-bearing ferrospinel (Mag). Sub-micron sized flecks of Au are found on the surface of a sul-mt droplet with scanning electron microscope (SEM).IntroductionSulfide ore deposits supply the world's mineral resource in the production of non-ferrous metals. Particularly, Cu-Ni deposits are chemically enriched in metals from high sulfur saturation during magmatic formation that creates the proper geochemical environment for metals enrichment [1, 2]. The sulfur and oxygen fugacity control redox conditions of a differentiated silicate/sulfur magmatic melt with the concentration of iron playing a dominate role in the chemical partitioning of metals in sulfide liquid [3, 4]. The initial magnetic crystallization of (Fe,Ni)i-xS monosulfide solution (mss) from metal-sulfide liquid has an exclusive effect on the fractionation of mineral assemblages (zoning) [5].Phase equilibria of sulfide melt (sul-mt) components are related by a miscibility gap with mss forming Ni-rich pyrrhotite (Ni-Po) followed by the crystallization of (Fe,Cu)1-xS intermediate sulfide solution (iss) [6]. Precious metals form stable chacogenides and are retained in solution until the final liquid solidifies. The redistribution of metals now occurs by subsolidus cooling of mss and iss that exsolve low-temperature Fe-Cu-Ni bearing mineral assemblages [7]. The proper interpretation of ore genesis increases processing capabilities by isolating chemically enriched zones during extraction and should be used to aid in sustainable mine site development [8-11]."

Jan 1, 2013

By Mikiya Tanaka, Mikio Kobayashi, Kazuya Koyama, Yoshihiro Nishisu

Preparation of multicomponent powders are very useful and important for producing the materials with complicated and homogeneous structure. Therefore multicomponent powders have a lot of attention in the field of advanced value-added materials. The aqueous processing in hydrometallurgy has a broad potential for producing multicomponent homogeneous precipitates. Furthermore the aqueous processing has a future potential for integrating the separation, precipitation and synthesis processes. In this presentation the precipitation from homogeneous solution including rare-earths and/or common metals is presented. These precipitates probably consist of almost monodispersed, multicomponent and spherical particles by precisely controlling several reaction factors, reaction temperature, concentrations of starting materials, pH and so on. The separation of the nucleation stage and the growth stage of the particles is very important and how to control the reaction factors to realize enough separation is discussed. In this presentation the systems of Y-Eu-0, Y-Fe-0 and Y-Al-0 are mainly presented. In addition the precipitation-stripping method from organic phase is presented focusing the synthesis of multicomponent powders of Ni-La-0 system. These precipitates have multicomponents homogeneously and so they are converted to multicomponent ceramic powders by calcination. They are important compounds as phosphor, opto-magnetic materials, optical materials, hydrogen storage alloy or as the related precursors. In this presentation some characterization of these particulate materials is included.

Jan 1, 1998

By Anat Deepatana

Bioleaching of nickel laterite ores is the extraction technology based on the use of heterotrophic micro-organisms and their organic acid products to dissolve metals from oxide minerals. This study examined the chemical leaching kinetics of limonite and nontronite ores with metabolites including citric, lactic and malic acids. The leaching process was found to follow the chemically controlled model. The leaching kinetics was found to be significantly influenced by the acid strength or dissociation of acids in solution. Although increasing the acid strength increased the rates of leaching, this trend was not indefinite. An optimal acid concentration that defined the fastest leaching rates was identified for each acid. The amenabilities of the minerals hosting the nickel and cobalt in limonite and nontronite to organic acid leaching were also established.

Jan 1, 2006

By V. I. Lakshmanan, R. Roy

"TiO2 is used in paints, plastics, rubber, paper, inks, textiles and other miscellaneous applications. The demand for the pigment grade Ti02 is growing at 3.0%/year on average and this invites the development of innovative and cost effective processes. The current processes are not designed to recycle the reagents and thereby discharge the effluents into the environment, causing an environmental concern.During this study, synthesis of TiO2 from an ilmenite concentrate was investigated using an innovative atmospheric mixed-chloride leach process. The solution purification was carried out using solvent extraction in two stages. In the first stage iron removal was carried out and in the second stage titanium was extracted. The strip solution obtained from the second stage solvent extraction contained the purified titanium and from this stream pigment grade Ti02 was recovered. The barren solution was used for reagent recovery and the regenerated leach liquor was recycled."

Jan 1, 2011

By R. G. Reddy

The Margules .equation is used for interpreting excess Gibbs energy of several ternary systems. In the present study activity coefficient of 'a dilute solute, 2, in a binary solvent 1-3 was derived. The derived expression is used to interpret logarithmic activity coefficient of oxygen and sulfur in several metallic systems. Self interaction parameter of the solute is derived from the partial function of solute using constant compositional path. An expression for logarithmic activity coefficient and self - interaction parameter of solute is also derived using Maclaurin infinite series. The derived equation is based on Maclaurin infinite series used successfully to deduce thermodynamics of self interaction of oxygen as a interstitial atom in two metallic systems. The predicted thermodynamic parameters values using Maclaurin infinite series and Margules. equations, are in excellent agreement with the experimental data and also our predictions are far more accurate than the predictions made by other models.

Jan 1, 1996

By Z. Q. Chen, M. H. Loretto, Y. G. Li

"As-cast, As-forged, as-solution-treated, and solution treated and aged microstructures of Ti-15Mo (IMI205) with and without carbon were examined using optical microscopy, scanning electron microscopy .and transmission electron microscopy. Tensile testing was carried out at room temperature. It was found that carbon acts primarily as a titanium carbide former: Titanium carbides increase slightly the tensile strength, but decrease the ductility of IMI205. These observations are interpreted in terms of the titanium carbide morphology observed using SEM and TEM and the phase diagrams of Ti-Mo, Ti-C, and Mo-C.IntroductionIn a recent study on the development of a burn-resistant 13-Ti alloy, carbon was introduced· into the Ti-V-Cr system in order to optimise the mechanical properties. Research results[1, 2] demonstrate that carbon addition can refine the 13 grain size and improve the stability of the 13 phase in Ti-V-Cr alloys. The most attractive result is that carbon addition produced a marked improvement in the ductility of alloys when the carbon content is over 0.1 wt.% in this alloy system. Even after long exposure, the alloy with carbon addition maintains good ductility. One of the main reasons for the ductilising of the alloy is that titanium carbides can getter the oxygen from the 13 matrix.In view of the success of carbon addition in improving the properties and the stability of the Ti-V-Cr alloy, it is of interest to investigate the behaviour of carbon addition in other beta Ti-base alloys. The objective of the present work was, therefore, to assess the microstructures and mechanical properties of IMI 205, a metastable beta titanium alloy, with and without carbon addition using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), wavelength dispersive X-ray (WDX) analysis, room temperature tensile testing."

Jan 1, 2000

By Zhen Zhang, Jiang Diao, Tao Zhang, Yi Ren, Lu Jiang, Xiao-Man Yan, Bing Xie

The precipitation behavior of phosphorus enrichment phase was investigated by slag modification with Al2O3. The mineral phase of the original slag and modified slags were measured by mineral phase microscope, SEM+EDS and XRD. The mechanism of Al2O3 modification was discussed according to the thermodynamic theory analysis software (Factsage version 6.3). The results show that the high phosphorus solid solution (nˊ2CaO·SiO2-3CaO·P2O5) was generated by the continuous reaction of nC2S-C3P (nˊ＜n) solid solution and Al2O3 under 1350℃. The amount of initially precipitated solid solution (nC2S-C3P) was reduced and even disappeared with the increasing of Al2O3. If the addition of Al2O3 is enough in the slag, the high phosphorus solid solution (nˊC2S-C3P) that generated by the above mentioned reaction will continue to react with Al2O3 to produce Ca2Al2SiO7 and even C3P, which was demonstrated that the addition of Al2O3 has a positive influence on the precipitation of phosphorus enrichment phase.

Jan 1, 2015

By D. J. Wang

Based on the thermodynamic arid kinectic aspects, the vaccum distillation processes for the separation and recovery of metals from wastes are analyzed. As to the separation criteria, The separation coefficient and equilibrium composition relation between vapor phase and liquid phase are the bases of recovery of metals by vacuum distillation, The vaporization rates and condensation mechanisms are also discussed. Some experimental results which deal with metals-containing wastes are described and the performances of a new kind of horizontal vacuum furnace are introduced, which demonstrate that , vacuum distillation may be a prospective technique for circulation and regeneration of some non-ferrous metals from industrial wastes.

Jan 1, 1996

By Liu Chunpeng

Under an inert atmosphere, the temperature enhancement of nickel bearing pyrrhotite irradiated by microwave was measured with a special metal-sheathed thermocouple and the non-isothermal rate equations were obtained. Under the controlled oxygen potential of the reacting gas in the microwave field, over 90% sulfur contained in the pyrrhotite is converted into elemental sulfur directly, the iron and the nickel are transformed into FeO,, NiO, NiFe,O, and FeSiO,. According to the experimental data the rate of the elemental sulfur produced is in diffusional control and the non-isothermal equation derived is

Jan 1, 1993

By A. Galvan

High rate compressible media filter (CMF) tests produced exceptional total suspended solids (TSS) removal at hydraulic loading rates ranging from 97.8 to 122.2 m/h. The compressible media is manufactured from a robust resin fiber that can withstand low pH and temperatures up to 149 °C. The media porosity can be varied by applying compression onto the media. At 40% compression, the CMF can remove particles greater than 4 μ. Three synthetic test-samples were generated by Hazen Research Inc., (Golden, Colorado) to simulate the copper Pregnant Leach Solution (PLS), Raffinate and Electrolyte solutions used for the testwork conducted at their facility. The preliminary results showed that the CMF was very effective in removing TSS without the use of chemical conditioning from the above test-solutions with efficiencies of 98%, 97%, and 96%, respectively. Given the remarkably high hydraulic loading rates, the industrial equipment footprint would be minimized appreciably over conventional clarification and alternative filtration systems.

By Marcio Toshio Tanaka, Marcelo Breda Mourao, Cyro Takano, Cesar Yuji Narita

"The concerns in questions related to the environmental impact in the steelmaking industries caused mainly on the gas emissions such as the dioxide carbon are due to its raw material such as the coal, a fossil and non renewable resource. The purpose of this paper is to replace from 10% to 50% of the coal used in cokemaking by mixing it with a renewable source (wood charcoal). The powder (- 325 mesh) from both raw materials (coal and wood charcoal) were mixed in order to obtain a briquette that was then heat treated at 1100°C to obtain the biocoke. Results of usual analysis (coke reactivity index, coke strength after reaction and cold crushing strength test) were employed to compare to regular coke briquettes. It was found that biocoke with different amounts of wood charcoal present features enabling it to be used in some ore reductionprocesses.1. IntroductionThe iron and steelmaking industry is a heavy emitter of carbon dioxide; according to the World Steel Association, 6.5% of global emissions of this greenhouse gas is due to the production of ferrous materials [ 1]. This is due to the fact that the fuel and reductant employed in the blast furnace is metallurgical coke, obtained from fossil coal. There are some projects aiming to reduce or even eliminate the emission of fossil GHG in the iron and steelmaking process [2]. Most of them propose the capture and storage of the gas (CCS) [3], a technology not yet proven. Other studies point out that the coke consumption in the blast furnace could be reduced by using high reactivity coke; this could lead to lower temperatures in the thermal reserve zone of the blast furnace and consequently less fuel rate in the furnace.The use of biomass in the iron ore reduction process is known as an environmentally accepted solution, as biomass does not release already fossilized carbon."

Jan 1, 2013

By M. Tamura, K. Fujita, K Shinozuka, H. Daimon, H. Esaka

"In-situ observation of unidirectional solidification using transparent substance has been performed to investigate the growth direction of solid phase. Cell or dendrite of which preferred growth direction is not parallel to the heat flow direction was observed with various solidification conditions. Dimensionless growth direction (p) changes from 0 to 1 with increasing growth velocity at a constant temperature gradient. Introducing the dimensionless growth velocity, the relation between p and growth condition could be correlated.IntroductionTransition in macroscopic solidified structure from chill to columnar zone which is found in normal castings takes place via grain selection1). Cast products such as turbine blades are unidirectionally solidified, grain selection plays an important role to choose suitable crystals which have reasonable orientation in the region called ""starter"", which is a very initial part of casting2). Therefore, grain selection is a very important process in the formation of casting structure. The present authors have been studying on the process of grain selection using succinonitrile, which is a transparent organic substance and have found that the growth distance necessary for grain selection depends upon the solidification condition3-5). When the solid/liquid interface is dendritic, the grain selection occurs quickly. On the other hand, when the solid/liquid interface is cellular, it occurs slowly. We supposed that the growth direction of dendrite is different from that of cell when the substance is unidirectionally solidified. Indeed, Kurz and Fisher wrote in their text book that dendrite grows along its preferred growth direction, <100>, regardless of heat flow direction and that cell grows along heat flow direction regardless of its preferred growth direction1). However, there is no quantitative description about the growth direction when the solid/liquid interfacial morphology is cellular. Furthermore, there have been little works6) to study the growth direction of cell and dendrite."

Jan 1, 2000

By Shaohua Ju, Feng Jiang, Chuanhua Li, Jinhui Peng, Libo Zhang

A T-junction microchannel is proposed to overcome the existing problems in conventional solvent extraction of indium from zinc hydrometallurgical process. Experiments were performed to separate In3+, Fe3+ and Zn2+ from sulfate solutions using Di-(2-ethylhexyl)phosphoric acid (D2EHPA) as the extractant. The effect of parameters such as pH, microchannel size and contact time on the extraction behavior of In3+, Fe3+ and Zn2+ was investigated. At contact time of 2.52 s and initial solution pH of 0.48, the extraction efficiency of In3+, Fe3+ and Zn2+ was 99.13%, 8.31% and 2.45%, respectively and separation factor of In3+/Fe3+ and In3+/Zn2+ were almost 1229.54 and 4864.98, respectively. Then, the loaded organic phase was stripped in T-junction microchannel. At contact time of 33.6 s, 99.64% of stripping efficiency of In3+ and stripping equilibrium were reached, while concentration of Fe3+ and Zn2+ was lower than 0.01 g/L with good separation of In3+ from Fe3+ and Zn2+.

Jan 1, 2016

By Y. Fukunaka, M. Niinae, E. Kusaka, T. Kuzuya, R. Ishii

"Samarium oxalattr particles was precipitated in oxalic acid aqueous solution from samarium-loaded D2EHPA solution emulsified with a conventional impeller. The calculated fractional precipitation of samarium oxalate was reasonably compared with the value determined by chemical analysis. Morphological variation of oxalate precipitate particles was then examined with H2C2O4 concentration in aqueous solution, Sm(III) and D2EHPA concentrations in organic phase. The needle-like precipitate was identified as Sm2(C2O4)3 10H2O by XRD. Precipitates obtained at higher H2C2O4· or Sm(III) concentration greatly decreased the length of major axis of precipitate, while those at higher D2EHPA concentration increased it. The oxalate was further precipitated under ultrasonic irradiation. However, the morphological variation caused by theses processing variables was not so evident under ultrasonic irradiation as in an impeller or shaking mixer.IntroductionThe materials processing of the rare earth elements must be reviewed from the scope of industrial ecology, since they have the potential applications of magnetic materials as well as secondary battery in developing programs of the electric vehicle. The technological trend to develop the electric vehicle may greatly influence the concept of materials processing, since the global· environmental problem must accommodate with the sustainable development for mankind. The recycle design must be a key issue in the materials science and engineering.Solvent extraction provides a unique separation technology -in this sense. Doyle (1)(2) reported the integrating solvent extraction with processing of advanced ceramic materials, whose chemical composition and microstructure must be precisely controlled. In her paper, the higher productivity inherent to the present process superior to hydrolyzing metal alkoxides was emphasized. Oxalic acid has been used as precipitant for rare earth purification process, since rare earth oxalate has a very small solubility in water and can be easily decomposed to oxide. It is thus suitable for precipitation stripping agent in cationic exchange type extracting system (i.e. D2EHPA, VA-10, PC-88A and so on)."

Jan 1, 2000

By Sergio Neves Monteiro

This work had as its objective the characterization of a waste material, steel slag, generated from an integrated steel plant, with a view to its recycling and incorporation into red ceramics fabrication. The characterization was performed in terms of chemical composition by X-ray fluorescence (XRF), particles size distribution, X-ray diffraction (XRD), thermal analysis (DTA/TG) and scanning electron microscopy (SEM). The results indicate that the steel slag presents high amount of Ca, Fe, Mg and Si. The weight loss of the steel slag at temperatures above 800oC is associated with calcium carbonate decomposition. The coarse particle size of the steel slag is inadequate for its direct recycling into red ceramic fabrication. It is necessary to screen or to grind the waste. As a possible solution, it is suggested that screening or grinding the steel slag to a convenient particle size distribution would allow its successful industrial incorporation into red ceramics products.

Jan 1, 2006