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By J. N. Kondo, M. Hara, T. Smida, N. Ooto, K. Domen

"A porous material composed of two-dimensional anionic sheets of a layered perovskite, KSrNb30 10, was studied as photocatalyst for the production of Hz in the presence of alcohol sacrificial donors. Colloidal single and multi-layered HSr2Nb30 10 sheets were formed by intercalating ietra(n-buthylammonium) cations into the interlayeres of H+-exchanged KSr2Nb30 10 (HSr2Nb30 10), and addition of HN03 solution to the colloidal suspension precipitated the porous materials in which HSrNb30 10 sh~ets rand~mly stuck together. Original HSr2Nb30 10 before exfoliation had a BET surface area of 1 m2 g-1, whereas the surface area of a porous material prepared under optimal conditions exceeded 100 m2 g-1. The porous HSr2Nb30 10 had considerably higher photocatalytic'activitie8 for oxidation of 1-propanol and 1-buthanol than HSr2Nb39io, indicating that in the porous materials many niobate sheets are available for decomposition of these large alcohols.IntroductionQuite a research effort has gone into the design and study of porous materials. Such materials with large surface areas would have applications in highly efficient adsorbents or catalytic reactions.We have been studying photocatalytic reaction by cation-exchangeable layered metal oxides, where alkali metal cations are intercalated into the interlayers of inorganic sheets.[1,2] There are several advantages to using layered compounds rather than bulk powders for photocatalysis. Layered compound is rich in variety, in addition, modifications of them are easily performed by exchanging alkali metal cations in the inter layers for H + or other metal cations. The most important advantage is that some layered compounds have considerably high photocatalytic activities than bulk catalysts because the electrons and holes generated in each thin inorganic sheet readily reach interlayer spaces as reaction sites at the illterlayer spaces. It should be very important for further improvements· of layered photocatalysts to utilize two-dimensional inorganic sheets effectively."

Jan 1, 2000

By M. E. Myers

An experimental program is being carried out to determine the thermodynamic characteristics of zinc solubilization in high-temperature iron and iron-carbon alloys. Two versions of an isopiestic technique are being used, with zinc at a lower temperature being equilibrated with pure iron foils or molten iron-carbon alloys at a higher one. The lower temperature sets the partial pressure of zinc vapor, and thus the activity relative to a given reference state. Initial results show Henrian behavior for dilute zinc solutions in austenite and a molten 4.6% C alloy, with unit-pressure solubilities in pure Fe that closely match the predictions of Wriedt.

Jan 1, 1992

By T. V. Jayaraman, Kranti Kumar, Paul Praveen J., Dibakar Das, A. R. James

"Lead free piezoelectric ceramics with high piezoelectric coefficients are in great demand for sensor and actuator applications. Synthesis and characterization study of one such lead free system, barium zirconate titanate - barium calcium titanate [xBZT-(1-x)BCT] (x = 0.5), via solgel method have been carried out. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of single phase BZT-BCT nanoparticles (<50 nm). The as-synthesized powders were calcined at 1000°C and the powders were pressed into cylindrical pellets. Solid-state sintering of the green pellets at 1550°C for 2 hrs resulted in single phase perovskite structure. Hysteresis loops were obtained which indicates the ferroelectric nature ofBZT-BCT. The bulk ceramic samples with the highest sintered density (~93%) were subjected to electrical poling and the piezoelectric properties ( d33, kp, & i:,) were measured. The structure and piezoelectric properties were investigated and correlated for the given composition of the BZT-BCT system.IntroductionPiezoelectric ceramics are widely used in various sensors and actuators and most of the piezoelectric ceramics, which are presently used, are lead based, which contains at least 60% lead (Pb) by weight. The critical disadvantage of these lead based piezoelectric ceramics is their hazardous effect related to the toxicity of lead, which poses a serious environmental concern starting from their processing to the disposal stage[l]. It is well known that a material to be a good piezoelectric it requires a morphotropic phase boundary (MPB) i.e. the composition induced phase transition between any two ferroelectric phases."

Jan 1, 2013

By Metehan Erdogan, Mustafa Serdal Aras, Sedef Cift Karagul, Ishak Karakaya, Esra Karakaya, Merve Kolay Ersoy

Pickling is the treatment of metal surfaces by removing oxide layer, rust, scale, inorganic contaminants or other impurities from ferrous metals, copper or precious metals. A strong inorganic acid such as hydrochloric acid is used for plain carbon or low alloy steel pickling. When the concentration of copper in the pickling solution exceeds about 100 mg/L, reversion may take place and randomly plating of copper onto the steel strips which causes visual incompatibility occur. Furthermore, efficiency of pickling decreases with the increase of copper content. The reversion may be delayed to higher Cu concentrations by adding fresh acid to the line. Increased acid consumption only delays the time to discard the solution but increases the cost and hazardous nature effect on the environment. An experimental electrochemical procedure has been conducted to remove copper from pickling solution to reduce the concentration below 100 mg/L. Within this scope, effects of applied current density, copper concentration and electrolysis duration on copper deposition were studied. Current density was determined as the most effective parameter to remove copper from the regenerated pickling solutions of steel plants.

Mar 1, 2018

By Toshiyuki Hiranami, Keizou Uematsu

"AbstractionSpray freeze drying method was proposed to fabricate ·ceramic: powder granules for high performance ceramics. Obtained granules and their green compact were characterized by SEM and immersion liquid technique. Granules have a spherical shape of about l 00 µ m in diameter, ·and no binder segregation was found with the immersion liquid technique. The granule had sufficient strength for usual handling, while the strength was much lower than that of granules prepared by conventional spray-drying. Unlike the conventional green compacts, granule interfaces were not observed in the green body made with the spray-freeze dried granules.IntroductionIt was well kn9wn that spray-dried granules have binder segregation layer on their surfaces. The trace of this segregation layer survives in the later processes i.e. compaction and firing, and behaves as fracture origins in the sintered bodies. The origin of this problem is solvent drying process from slurry droplet surface in spray drying system. As alternative method we propose a freeze drying process for granule preparation, in which solvent is remove by sublimation though the process, binder segregation can be prevent.In this study, we applied spray freeze drying method to fabricate alumina powder granule, and characterized the obtained granules, and their green compacts and sintered bodies.Experimental procedure.Alumina powders and additives aqueous solution were mixed for 24 hours using a ball mill to· prepare the slurry for spray freeze drying. .The solid loading of the slurry was 30vo1%. Deflocculant (PAA-NH4 type) was added 0.5mass%, and the binder (PVA). 1.0, 2.0 or 3.0mass% of alumina. Obtained slurries were sprayed into liquid nitrogen to make frozen granules. The granules were freeze dried.For the characterization of the granules, immersion, liquid technique observation and single granule strength test were carried out. Strength of individual granule wa5 measured using micro compression testing machine (MCTM, SHIMADZU). Granule strength was calculated from following equation."

Jan 1, 2000

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 Edwin Adoyi Ali, Zainab Shehu Aliyu, Adele Dzikwi Garkida, Muhammad Dauda

Feldspar from Matari, Nigeria was analyzed using SEM, XRD and XRF techniques for microstructural analysis, mineral phase analysis and chemical composition analysis respectively. Qualitative and quantitative XRD analyses revealed the presence of microcline 59.6%, albite 34.7% and quartz 5.71%. The XRF results showed that the feldspar contains 67.32% SiO2, 17.54% Al2O3, 11.33% K2O, 2.75% Na2O, 0.12% CaO, 0.01% MgO, 0.02% MnO2, 0.10% Fe2O3, 0.00% Ti2O, etc and 0.14% LOI. SEM/EDX analysis shows the presence of microcline feldspar as the dominant phase, exhibiting lamellar twinning. The XRD has also revealed that potash has the highest peak, indicating its high concentration. The 0.10% Fe2O3 present is within the permissible level (0.1-0.3%) for glass making and also within the potash feldspar specifications (0.17%). The Matari feldspar is a microcline type, rich in potash, alumina and silica, enabling it meet the standard specifications for alumino-silicate glass.

Jan 1, 2015

By H. Hahn, B. H. Kear, K. Kan, S. C. Danforth, G. Skandan, W. Chang

"A new chemical synthetic process for the production of non-agglomeratednano structured ceramic (n-ceramic) powders, starting from metalorganic precursors, is described. The process combines rapid thermal decomposition of a precursor/carrier gas stream in a hot tubular reactor with rapid condensation of the product particle species on a cold substrate. Critical to the success of this Chemical Vapor Condensation (CVC) process are (1) a low concentration of precursor compound in the carrier gas, (2) rapid expansion of the gas stream through an uniformly heated tubular reactor under a reduced inert gas pressure of 1-35 mbar, and (3) rapid quenching of the gas phase nucleated clusters or nanoparticles as they exit from the reactor tube. A wide variety of metal organic precursors is available commercially, all of which can be utilized in the CVC process to produce n-ceramic powders, including single phase, multiphase and multicomponent systems.The CVC process has been used to synthesize non-agglomerated n-SiCxNy and n-ZrOxCy powders, with controlled particle size in the range 2-20 nm. Heat treatment of the assynthesized n-powders in various high purity gas streams causes compositional and structural modifications, including particle purification and crystallization, as well as transformation to a whisker-like morphology. Thus, as-synthesized amorphous n-SiCxNy particles transform to (1) cubic n-SiC particles, when heated in flowing argon at temperatures> 1350 °C, (2) hexagonal n-Si3N4 whiskers, when heated in flowing NH3IH2 at 1400 °C, and (3) cubic nSiC whiskers, when heated in flowing H2 at 1400 °C.Non-agglomerated n-ceramic powders form uniformly dense powder compacts by cold pressing, which can be sintered to theoretical density at temperatures as low as 0.5 Tm' For example, full densification ofn-Zr02 powder compacts under free sintering conditions can be achieved at 1125 °C."

Jan 1, 1994

By Subagyo

The condition of slag in a pyrometallurgical reactor is vital to ensuring control of the process. A new technique based on multivariate image analysis (MIA) of digital images has been developed to provide an online measurement of important slag characteristics, such as the presence of exposed metal, the presence of solid phases, and temperature. This paper shall describe the technique and provide some results from analysis using industrial plant data.

Jan 1, 2003

By G.A Subagyo

The condition of slag in a pyrometallurgical reactor is vital to ensuring control of the process. A new technique based on multivariate image analysis (MIA) of digital images has been developed to provide an online measurement of important slag characteristics, such as the presence of exposed metal, the presence of solid phases, and temperature. This paper shall describe the technique and provide some results from analysis using industrial plant data.

Jan 1, 2003

By R. L. Player

"The Copper Isasmelt process has been developed over the past 15 years by Mount Isa Mines Limited (MIM) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The first two commercial plants were commissioned in mid 1992.The results of four heat balances on the Mount Isa plant are presented. At a smelting rate of 98 t/hr of chalcopyrite concentrate plus 14 t/hr reverts, the total heat generated was -91MW. Approximately 39% of this energy came from coal, while 50% of the energy reported to the process waste gas. To a first approximation the furnace is near chemical equilibrium.The impurity distribution in the Mount Isa plant was presented. Approximately 91 % As, 85% Cd, 75% Bi, 68% Zn, 60% Sb and Tl, 45% Pb and 30% Te in concentrate was eliminated from the matte.The ""bubble"" frequency of the gas cavity below the foot of the lance was measured at -2. 1Hz. Side bands displaced by -l.lHz modulated the bubble frequency. This was consistent with radial gravity wave motion in the slag bath. The two processes, gas bubbling and wave motion appeared to be coupled together; the bubble frequency was twice the slop wave frequency. IntroductionCopper Isasmelt has been developed over the past 15 years by Mount Isa Mines Limited and the Commonwealth Scientific and Industrial Research Organisation. The process is based on the Sirosmelt lance, invented by researchers at the then Division of Mineral"" and ProcessEngineering ofCSIRO in 1973.The first two commercial scale copper furnaces were commissioned at Mount Isa and the Cyprus Miami Mining Corporation smelter at Miami, Arizona in August and June 1992 respectively.The process concept, the history of the development, and the Mount Isa plant have been described (1, 2, 3).This paper sununarises heat balances obtained on the furnace, the impurity distribution among the output streams and lance injection characteristics."

Jan 1, 1996

By D. Valic

In 1997, 9.2 million tonnes of mined, recoverable copper was produced, of which, 1.8 million tonnes or 19.4% was produced by leaching, solvent extraction and electrowinning. The amount of copper produced by this method grew faster than those attained from concentrate smelting, signifying the growing importance of this low-cost production method. Statistical experimental design, unlike traditional approaches, allows for proper distribution of experiments within the boundaries of factors being studied such that the number of experiments required to develop a sound relationship between the factors and a response is minimized. In the past, very little use has been made of statistical experimental design in copper electrowinning studies. Traditional one- variable-at-a-time approaches are widely employed for this purpose. The present study employs a factorial experimental design to relate current efficiency with current density (180 and 300 A/m2), copper concentration (25 and 65 gL), and temperature (40 and 60 °C). Pure synthetic electrolyte with a constant acid concentration of 180 g/L was used throughout the study. The designed study produced a linear relationship where the independent variables of current density, copper concentration, and temperature, and their interactions, were found statistically significant. It was shown that current efficiency could not solely be used as a predictor of copper cathode quality. The quality of the deposit is difficult to be incorporated into a model or relation. It was determined that other measures, such as cathode morphology and crystal structure should be considered. This was done through XRD and SEM analysis.

Jan 1, 1999

By Ioannis Paspaliaris, Dimitrios I. Gerogiorgis, Dimitrios Panias

"Red mud fiberization is a process with remarkable potential, alleviating environmental pressure by transforming an aluminum by-product into mineral wool, thus to various marketable products. A promising mineral wool process is molten slag fiberization via an impinging air jet, which avoids mechanical wear and rotating parts. The molten slag which remains after pig iron casting flows out of a heated ladle orifice at a high temperature (1600 °C) and adjustable flowrate, and forms a free-falling vertical jet which visibly radiates its excessive heat: at a given distance, a high-velocity impinging air jet meets the vertical melt jet perpendicularly (or at an angle), inducing intensive droplet generation, subsequent fiber elongation, collection and processing.This paper focuses on high-fidelity CFD modeling of the molten jet flow under external cooling: the model encompasses all physicochemical phenomena (melt laminar flow, radiative cooling) and considers several temperature-dependent slag transport properties in order to understand which operational degrees of freedom (manipulated variables) are useful to process optimization."

Jan 1, 2012

By Sergio N. Monteiro

Polymer matrix composites have been applied in components such as helmets and shielding for which toughness is a major requirement. Natural fiber presents interfacial characteristics with polymeric matrices that favor a high impact energy absorption by the composite structure. The objective of this work was then to assess the Izod impact resistance of polymeric composites reinforced with different amounts, up to 30% in volume, of a promising high strength natural fiber from the Amazon region known as curaua. The results showed a remarkable increase in the notch toughness with the amount of incorporated curaua fibers. This can be attributed to a preferential debonding of the fiber/matrix interface, which contributes to an elevated absorbed energy.

Jan 1, 2009

By Hiroaki Nakano, Kenji Hara, Shunsuke Kawano, Takeshi Ohgai, Michiaki Ikeda, Hisaaki Fukushima, Shinji Yamashita, Tetsuya Akiyama, Hisayuki Kaku

"Ni-Fe alloys have an inverse magnetostrictive effect (Villari effect) in which its permeability varies according to the ·applied strain. This alloy film has a potential for application as force sensors such as torque sensors, tension sensors and so on. Electrodeposition is promising as a technique for preparing Ni-Fe alloy film because of its convenience and economy. In this paper, the effects of electrolysis conditions on the magnetic properties of electrodeposited Ni-Fe alloy films were investigated. Hysteresis loops of Ni-Fe alloy films on copper substrates from sulfate bath were measured by a vibrating sample magnetometer (VSM). The films of low coercivity, which were preferred when used as a force sensor were obtained by introducing certain additives to the sulfate type bath.INTRODUCTIONNi-Fe alloys show an inverse magnetostrictive effect (Villari effect) that their permeability varies depending on the applied strain. The films of this alloy have a potential for application as force sensors such as torque sensors, tension sensors and so on. The authors et al. tried to prepare Ni-Fe alloy films using the sputtering technique, and produced a prototype of Ni-Fe alloy torque sensor [I]. The sensitivity was higher in the torque sensor thus produced than the strain gauge type one, and this torque sensor enables non-contacted detection. It showed excellent durability and reliability. However, the formation of Ni-Fe alloys by sputtering requires higher costs and brought an another problem that the shape of the substrate on which the film was formed was considerably limited. This causes a hindrance to the wide-range application of the force sensors. Electrodeposition is promising as the technique for preparing Ni-Fe alloy films because of its convenience and economy. In this paper, the effects of the conditions of electrodeposition on the magnetic properties of Ni-Fe alloy films were studied."

Jan 1, 2000

By Junji Shibata

Zeolite synthesized from coal fly ash has many intelligent properties such as cation exchange, adsorption, catalyst and so on. The suitable use of the zeolite, however, is not established in an actual commercial scale yet. From the viewpoints of an effective usage of coal fly ash and the zeolite obtained from coal fly ash, we propose the new concept for environmentally friendly usage of zeolite, in which coal fly ash safely returns to the soil with growing plants and purifying wastewater. This method can make great contribution to recycle of coal fly ash, to purification of high nutritious water and to tree planting.

Jan 1, 2002

By A. R. Udupa

The reduction roasting behavior of chalcopyrite has been investigated using various combinations of a desulfurizing agent, i.e., CaO or Na2CO3, and a reductant, i.e., CO, H2 or C. Using these, combinations the sulfur is removed from the mineral as CaS or Na2S rather than SO2 as is the case with conventional copper smelting and converting. The laboratory reduction ex¬periments were conducted using thermogravimetric analysis (TGA) and boat tests of mixed combinations of fine particulate reactants subjected to a continuous gas stream. The degrees of metallization were determined by both weight loss and chemical analysis methods and the products examined using optical and scanning electron microscopy and electron probe microanalysis. The percent reduction after one hour at 900°C ranged from 60% to 94%. From these data It was possible to provide postulations as to the controlling reduction mechanisms.

Jan 1, 1983

By Y. Ikeda

Typical electric appliances were dismantled into component pieces to study the recyclability of these discarded goods. Types and weight ratios of these component materials were investigated and characterized. The results showed that if they are dismantled properly, these goods could be classified into several groups of similar materials and/or structures, namely those consisting of single materials, metal-plastic combinations, metal-metal combinations and complex combinations of many different materials. By separating each combination into recyclable materials and isolating hazardous materials, it was found that the final waste for disposal could be reduced and the recycling efficiency could be improved markedly as compared to the conventional shredding method. The metal-metal combinations account for 60% by weight of the total metal contents in electric appliances, and therefore, it becomes important to segregate these metals. For the complex combinations, a process consisting of pyrolytic decomposition of plastic contaminants followed by smelting of the residue is proposed. It is anticipated that nearly zero-emission recycling of electric appliances will be achieved by applying this treatment process.

Jan 1, 1995

By K. Alibhai

Greek laterites, which generally had nickel concentrations of < 1 %, are amenable to chemical leaching,. although there is considerable variability in the ease of leaching with different ore types. With low grade ores(< 1 % Ni content); >70% of the nickel was leached in columns with a strong selectivity for nickel over iron. Heterotrophic microbially assisted leaching could be a viable alternative to classical hydrometallurgical and/or pyrometallurgical techniques, with a very high recovery (greater than 80% ) being found with some of these mineral microbial interactions. Critic acid was probably the effective chelating agent.

Jan 1, 1991

By Guilian Gao

TbFeCo is a common choice for many rare-earth transition metal films currently used as the magneto-optic layer for magneto-optical: recording devices. Since the environmental stability of RE-TM alloys is typically poor compared with traditional metal oxide particle media, such devices rely on multiple functional overlayers (metallic and/or dielectric) and organic coatings for durability. This paper presents an electrochemical evaluation of the degree of protection of several candidates for the reflective layer, Al, AlCr and AIPt and for the dielectric layer, SiN, AISIN and AIN. Cyclic voltammetry In 0.2M K2SO4 solutions at room temperature revealed that AIPt film offers superior corrosion protection compared to Al and AICr films. Of the three dielectric layers examined, SIN seems to be the most corrosion resistant. Examination by optical and scanning electron microscope confirm the findings of electrochemical experiments. The corrosion resistance of single layers of Al, AICr and AIPt has also been examined and factors affecting their performance are discussed.

Jan 1, 1992