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By Peter Kong

This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those produced in high intensity arcs, plasma torches, or in high intensity, high frequency discharges. Although nonthermal plasmas are at room temperatures, they are extremely effective in producing activated species, e.g., free radicals and excited state atoms. Thus, both thermal and nonthermal atmospheric-pressure plasmas are finding applications in a wide variety of industrial processes, e.g. waste destruction, material recovery, extractive metallurgy, powder synthesis, and energy conversion. A brief discussion of recent plasma technology research and development activities at the Idaho National Laboratory is included.

Jan 1, 2006

By Norihiro Murayama

The hydrothermal syntheses of zeolites from coal fly ash were carried out using NaOH and KOH as an alkali source. The cation exchange capacity (CEC) and the ion exchange selectivity were investigated for the zeolites synthesized by a hydrothermal treatment. The effective usage of the zeolite as a cation exchanger was considered from the viewpoint of engineering. Zeolite P, HS (hydroxysodalite) and K-CHA (potassium-chabazite) are mainly formed as zeolite species in NaOH or KOH solution at 393K. The zeolite P and K-CHA have a large exchange capacity as a cation exchanger. The cation exchange isotherms of various monovalent and divalent cations with various zeolites are investigated. The order of selectivity of the zeolites is as follows, NH4+> K+> Li+.For the divalent cation, the largest removal amount is obtained for Pb2+ in the low equilibrium concentrations below 0.2mmol/dm3, and almost perfect removal can be achieved for Pd2+. The order of selectivity of zeolites in low concentration is expressed in the following order; Pb2+> Co2+> Cd2+> Ca2+> Mg2+> Ni2+. Ii is considered the zeolites obtained from coal fly ash can be used as an excellent cation exchanger.

Jan 1, 2006

By Yuya Nakai, Kuniaki Murase, Kazuhiro Fukami, Atsushi Kitada, Ken Adachi

Concerning nodulation in copper electrore fining, it has been reported that short circuits caused by nodulation have the largest impact on the current efficiency. Therefore, to improve the current efficiency, it is important to prevent nodulation. In this research, the nodulation growth was investigated by replicating nodulation in the laboratory. The experiments were conducted by cathodic electrodeposition on copper plates attached to copper sticks of various heights. The nodulation was analyzed in terms of growth rates versus the initial heights.

Mar 1, 2018

By Wang Yun-yan

In order to examine the adaptability and the kinetics of leaching different gold ores in alkaline thiourea system, six kinds of gold concentrate and/or calcine with different physical and chemical properties were chosen as objects. The leaching behaviors in alkaline thiourea system with high stability, acidic thiourea system and alkaline cyanide system were compared. Changes of phase, surface appearance, particle distribution and specific surface area of six kinds of gold ores before and after leaching were studied in virtue of modern analytic techniques, e.g., XRD, SEM, and so on. The results indicate that alkaline thiourea solution can be used to leach gold ore, for oxidized gold concentrate removed arsenic by microbe pretreatment(4#) the leaching rate of gold is up to 82.68%, such conclusion overthrows the parlance reported that pH value must be less than 1.78, or gold can not dissolve in thiourea solution. Chemical components and phase are related to gold leaching rate, different gold ores are fit for different leaching system, and alkaline thiourea solution is suitable for the pretreated oxidized gold ores with low content of sulfur and in which the main phase was SiO2, phase almost does not change after leaching basically. Generally speaking, when leaching in alkaline thiourea solution, surfaces of gold ores with glaze change greatly to ones with coarseness, distinct trace and holes of corrosion. Particle size decrease and specific surface area increase of gold ores after leaching in alkaline thiourea solution with high stability except gold concentrate of Zhongyuan gold smelter(5#).

Jan 1, 2006

By Sung Jin Han

Magnesia-based refractory is generally used in an electric arc furnace (EAF) due to its relatively high corrosion resistance and strength at high temperatures. However, the magnesia refractory is attacked by EAF slag and thus the lining life continuously decreases. Thus, it is significant to identify the interfacial reaction between magnesia refractory and FeO-rich EAF slags. In the present study, the influence of FeO-rich slag on the corrosion behavior of MgO refractory was evaluated. The (Fe,Mg)Oss layer was observed at the slag-refractory interface and its thickness increased with increasing content of FeO in the slag. The specific reaction phenomena and formation behavior of (Fe,Mg)Oss layer were evaluated by thermochemical computing program, FactsageTM7.0.

By Jorge A. S. Tenório, Pedro F. A. Prado, Denise C. R. Espinosa

There has been an increasing push to develop environmentally sound recycling processes of electronic waste (WEEE), including end-of-life photovoltaic modules, to reclaim materials such as silver which is both valuable and pollutant to human health and wildlife. However, process sustainability and economic feasibility of PV panels recycling is strongly tied to the materials separation step, which currently presents challenges due to use of high temperature treatments and strongly acidic solutions. A method using an easily accessible solvent — isopropanol— dissolved the silicone-based encapsulant of crystalline silicon PV modules in 2 days at room temperature, separating the module into semiconductor wafer, glass, ribbon and backsheet.

Mar 1, 2017

By Weizhi Zeng, Michael L. Free, Sayan Sarkar, Prashant K. Sarswat

Black Phosphorus was recently discovered as a 2D material and it exemplified huge prospects for application in electronics, optoelectronics, photonics and catalysis. It is a direct band semiconductor with tunable band gap varying from 0.35 eV (bulk) to 2 eV (single layer). But the layer dependent band gap of black phosphorus restricts it to make use of the full spectra of sunlight for absorption. First principle calculations were performed using ‘Quantum Wise Atomistic Toolkit’ package with Perdew-Burke-Ernzerhof (PBE) exchange-correlation for black phosphorus doped with non-metallic dopants of B, S and Se and metallic dopants of Ti, Mg and In. It has been found that doping with non-metallic impurities result in a small diminution of the band edges (0.96–0.57 eV), whereas doping with metallic impurities decrease the band edge drastically (0.85–0.025 eV). Moreover, it was also observed that dopants with an even number of valence electrons incorporated a metallic nature of black phosphorus, whereas dopants with odd number of valence electrons further attributed to its semiconducting features. Thus in a holistic discernment, black phosphorus with the incorporation of some dopants in appropriate amounts can absorb more visible range of the optical spectra, making it ideal for use in photovoltaics.

Mar 1, 2017

By J. R. Parga

A shortage of landfill space and growing environmental concerns in Mexico are renewing interest in the recyclability of scrap from automobiles. This work describes a pyroumetallurgical process for the recovery of metallic lead from waste lead paste. Argentopyrite concentrate is commingled with lead paste residue and smelted in a fuming process thereby transferring the precious metals into lead bullion. The process consists of smelting lead paste and argentopyrite, sodium carbonate, and metallic iron at smelting temperatures of about 1100 T. The reaction products are slag and molten lead bullion enriched with precious metals. A major feature of this process is the removal of precious metals from the bullion by means of zinc, whereby a silver-zinc intermetallic compound is formed and floats out of the lead. The recoveries of precious metals are about 98%.

Jan 1, 1996

By Yuya Nakai, Kuniaki Murase, Kazuhiro Fukami, Atsushi Kitada, Ken Adachi

The resources of vanadium –titanium magnetite in China are very abundant, most of which are used to prepare titanium-rich materials. Titanium pigment, electric welding bar and titanium sponge are made from titanium-rich materials such as synthetic rutile and titanium slag etc. To fully utilize titanium resources, many production methods of titanium-rich materials were proposed. In this article, authors review on methods of preparing titanium-rich materials which are Electric Smelting Process, Reduction-rust Process, Selective Chlorination Process, Acid Leaching Process, and sum the advantages and disadvantages of them. Existing problems and possible tendency of production methods of titanium-rich materials are also discussed.

Mar 1, 2018

By Keizo Uematsu, Satoshi Tanaka, Nozomu Uchida, Anze Shui, Joaquin Lira, Cyril Lavelle, Midori Saito, Thierry Poirier

"Dispersed and flocculated alumina (non-spherical particles) slurries were prepared by pH controlling with HCL Spray-drying of these resulted in dimpled granules with a smooth surface and high density, and spherical granules with rough surface and low-density, respectively. Detailed characterization on granules and their compacts includes: SEM observation, density measuring (mercury porosimetry and Archimedes's Principle) and liquid immersion optical microscopy. Compaction of these granules originated a larger particles rearrangement in the samples made with the spherical granules than with the dimpled granules. This was verified through the orientation of alumina particles, which was pronounced in the compact made with the former granules.IntroductionOn immersing a ceramic powder in water, the surface usually acquires a charge by interaction with ionic species in solution. The charge is affected by pH and the electrolyte concentration of the water. 1 The dispersion in a slurry is achieved through the interaction of charges on the particle surface with the media. In the ceramic processing, especially in the process of casting, the dispersion of slurry has been one of the most important topics studied for many years. Recently the attention is paid on its role in the pressing. The granule characteristics are governed by the dispersion state of slurry. Takahashi et al2 , Tsubaki et al3 and Walker et al4 showed that the granules from dispersed slurry were dimpled and of high density, while granules from flocculated slurry were spherical and of low density. This variation in the granules characteristics should have a marked effect on the structure of compact.This paper presents the influence of the dispersion state of alumina slurry on the granules characteristics and also on the internal structure of compacts. Different dispersion states were elaborated by adjusting pH of the slurry. In this method, the particles are dispersed or flocculated only by the effect of surface charging, and thus some secondary effect such as the steric hindrance from an electrolyte dispersant is avoided. The characteristics of granules and compacts are examined with SEM, density measurements by mercury porosimetry and by Archimedes's Principle and liquid immersion optical microscopy. This novel microscopy provides various important information on packing structure of particles, such as their orientation. 5"

Jan 1, 2000

By C. E. M. Meskers, U. Boin

"The increasing use of coated magnesium in consumer products results in creation of coated Mg scrap during product manufacture and after End-of-Life product treatment. Currently this material is generally not recycled, leaving a material resource unused. Closure of the magnesium cycle in a sustainable manner is necessary. In order to do so, the effect of coatings on the recycling process has to be quantified, predicted and minimized. For this purpose metrics have been developed, based on first principles supported by detailed understanding of the recycling process. The developed 3D metric enables quantitative assessment of the recyclability and links coating design, product design and recycling to each other in a visual manner. The parameters that form the metric can be measured and predicted, hence an engineering basis for Design for Sustainability of coated magnesium is provided.IntroductionEvery product progresses through the four phases of the product life cycle depicted by figure 1. In each phase residues are created. Their amount and composition is largely determined by the complex material combinations created/invented during product design in the manufacture phase. Compared to the ideal cycle the magnesium cycle is far from closed (fig. 2). Most noticeable is absence of the link between the EoL phase and raw materials production. A closed cycle only exists for class 1 scrap, which goes from the product manufacture phase directly to production from industrial material and returns to the manufacture phase as magnesium alloys. The four problematic streams are marked by ???. Coated semi-products are present in two of the four residues, namely in rejects and collected scrap. When these semi-products are recycled the amount and composition of the dross and salt slag residue is affected as well.During product design selection of the coating takes place, fixing the coating character¬istics and properties from this moment on for the rest of its life cycle. The choices made in the manufacturing phase are therefore critically linked to the recyclability of coated semi-products as well as the sustainability of the magnesium cycle as a whole. Sustainable closed life cycles, in which the quality of materials is preserved and residue creation and resource depletion are minimized, can be attained by selecting the appropriate alternative during product design. To realize this the effect of design choices on the life cycle and more specific the recycling process has to be known and quantified."

Jan 1, 2008

By Yasuhiro Konishi, Norizoh Saitoh, Toshiyuki Nomura

This paper describes a new recycling method, based upon biotechnology, in order to extract platinum group metals (PGMs) from post-consumer products. The metal ion-reducing bacterium Shewanella algae was found to exhibit the ability to reduce and deposit PGMs. An integrated bioprocess using Shewanella bacteria to selectively recover Pd, Pt, and Rh from aqua regia leachates of spent automotive catalysts is demonstrated.

Mar 1, 2017

By J. Shibata

The recovery process of valuable metals, such as Ll, Mn, Ni and Cr from a waste lithium battery was developed n this study. Lithium and Mn are selectively leached from the battery by using dilute mineral acid. Main part of the battery comprises stainless steel, and Fe, Ni and Cr are easily leached by the mixture of dilute HCl and HNO3 Lithium and Mn are precipitated as metal carbonates from the? individual leached solution with sodium carbonate solution. The solution containing Fe,Ni and Cr Is treated by solvent extraction to separate NI and Cr from the leached solution. The experiments are carried out for leaching and separation steps. According to the experimental results, the flow. sheet for a recovery process of valuable metals from a waste lithium battery has been established.

Jan 1, 1995

By Sung Tae Kim

The viscosity is one of the most critical properties of slags and thus its influence on the physicochemical phenomena in metallurgical processes has been issued for last decades. The viscosity of ferrous- and non-ferrous metallurgical slags can be understood via structural investigation with spectroscopic methodologies including x-ray photoelectron spectroscopy, infrared- and Raman spectroscopy, and solid state nuclear magnetic resonance spectroscopy, etc. Therefore, the reaction kinetics such as desulfurization in ladle metallurgical furnace, reduction of FeO and MnO in electric arc furnace is strongly dependent on the viscosity of the slags. The rates of oxide (inclusion and refractory) dissolution into the slags and fluxes are governed by the viscosity. Alternatively, the structure of aluminosilicate melts also affects the thermochemical properties such as sulfide capacity, etc. These diverse applications of the viscosity-structure relationship to ferrous- and non-ferrous metallurgical processes were reviewed.

By Z. Sadowski

The influence of organic acids simple salts and A. niger saccharose and molasses worts on sodium oleate adsorption on the salt-type mineral surfaces has been studied. It was found that salts of organic acids had an effect on the sodium oleate adsorption on barite calcite and magnesite. The collector adsorption on the barite and calcite surfaces decreased under the influence of investigated worts. Experimental data suggest that the biomodification of salt-type mineral surfaces can be used for the selective separation of these minerals.

Jan 1, 1991

By Thamyres C. Carvalho, Edemarino A. Hildebrando, Roberto F. Neves, Francisco R. Valenzuela-Diaz

Synthetic clays are an option of materials that can be modified to obtain better and specific properties when compared with natural clays. Although clays are found in nature, they have many disadvantages that limit the use of them, such as existence of impurities, and variations in composition. Therefore, the objective of this work was to obtain synthetic clay/polyester resin nanocomposites. To characterize the clay, we used X-ray Diffraction (XRD), Total Attenuated Reflection Spectroscopy in the Fourier Transform Infrared Region (ATR-FTIR) and Scanning Electron Microscope with Field Emission (FEG-SEM) methods and the nanocomposites were characterized by XRD and mechanical resistance to compression. The results show the purity of the clay and the time of synthesis is an important parameter for its crystallization process. The clay/polyester nanocomposites were obtained and showed an increase in the ductility.

Mar 1, 2018

By Kristine Bruce Wanderley, Denise Crocce Romano Espinosa, Jorge Alberto Soares Tenorio

Magnesium is present in nickels leach liquor and it is often disposed in waste barriers. However, new technologies with the aim of recuperating magnesium and other metals in the liquor have proven that it is possible to reduce the amount of metal lost during nickel ore processing. In this context, high temperature crystallization removes magnesium, with a concentration of 8 g/L, as MgSO4 H2O from the leach liquor. Kinetic studies of this process are needed to evaluate the thermodynamics of the growth of crystals. Thus, this work aims to study the crystallization kinetics of MgSO4 H2O. Temperatures of 230, 210 and 200 °C were investigated in a batch crystallization system in solutions with pH2. Aliquots were taken at each hour up to 5 h of time residence and analysed by ion chromatography for magnesium concentration. The reaction mechanism as well as rate constant and activation energy for each reaction temperature were obtained

Mar 1, 2018

By Guihong Han, Wei Wang, Chaolei Lv, Yongsheng Zhang

Silica aerogels are promising in many applications because of their excellent properties. However, the real applications of pure silica aerogels are limited because of their fragile network structure. We have prepared silica aerogel composites using humic acid as a composite material for improving the performance of silica aerogels and valorization of humic acid. The silica hydrogel composite was prepared using sodium silicate as a precursor and humic acid as a composite material by acid-base catalysis and sol-gel method. The hydrogel was followed by freeze-drying to obtain composite aerogel. The microstructures, specific surface area, and functional groups of silica and composite aerogel were characterized using scanning electron microscope (SEM), brunauer-emmett-teller (BET) and fourier transform infrared spectrometer (FTIR). The results demonstrated that the specific surface area of the silica composite aerogel was 307 m2/g under the condition of pH at 6, the mass ratio of silicon to humic acid (HA) at 3.82 and the molar ratio of N, N-dimethylformamide (DMF) to silicon at 0.9. X-ray diffraction (XRD) showed that the silica (composite) aerogels were amorphous. Thermogravimetric analysis (TGA) revealed that the silica aerogels lost weight from 150 to 250 °C and humic acid decomposed between 350 and 500 °C, and then the mass of the sample remained stable.

Mar 1, 2018

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 Dai Yongnian

"The feasibility to vacuum distillation of a crude metal or an alloy was discussed. The equilibrium relationship between vapor phase and liquid phase in A-B system - - - - - PA/PB =BAa*/b has been derived. The separation coefficient, BA = rAPA/(rBPB) is a judgment criterion. By calculation PA/PB, the equilibrium composition diagram of vapor phase and liquid phase was drawn. By use of the equation derived by M. Olette, the relationship among the volatilization amounts of various impurities in a crude metal (yi) was further solved. 1-(X/100)= C =(1-Y1/100)1/02i . From yi value obtained in practice, 2i, Pi and then can be calcu-lated. The correct volatilization order of various impurities was obtained. These results can be applied to determine the practical conditions (temperture, vacuum degree, type of distilla¬tion furnace, times of distillation and control of product composition) in distillation of a crude metal or an alloy.INTRODUCTIONRefining and separation of various impurities from nonferrous crude metals by vacuum distillation have many the advantages of high metal recovery, impurities recovered in metallic state, flowsheet simplified, good enviromental protection, low operation costs and in complex equipment. So in recent years this method has been adopted widely.Vacuum distillation has also been studied and used in separation of various elements from non-ferrous alloys and the area of its application is being extended rapidly.At this situation, some problems have been put up: What kind of impurities can be removed from crude metals? What kind of alloys can be separated by vacuum distillation? In present paper, attemps have been made to answer these problems and combine with practical results to analyse some valuable data obtained from testwork on vacuum distillation of crude tin and Pb-Sn alloy."

Jan 1, 1988