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By Junji Shibata

The waste acid mixture whose main component is phosphoric acid, is discharged from the etching process in the liquid crystal production industry. In order to separate impurity acids from the phosphoric acid, trioctyl phosphate (TOP) is used as an extractant. TOP can extract acetic and nitric acids selectivity. The extraction and stripping operations are carried out for the acid mixture by beaker-scale experiments and countercurrent multistage operations with mixer-settler equipment. TOP selectively extracts the acetic and nitric acids in the acid mixture. From the results of the McCabe-Thiele analysis obtained by beaker-scale tests, the extraction for acetic and nitric acids are approximately 100%, respectively, by 6-stage extraction with a phase ratio (A/O) of 0.4. On the other hand, almost all of acetic and nitric acids are stripped with water from the organic phase by 4-stage stripping with a phase ratio (A/O) of 1.0. About 95% of acetic and 98% of nitric acids can be removed from the acid mixture without extracting phosphoric acid in case of the mixer-settler equipment operation. There are several steps such as slicing, lapping, chemical etching and mechanical polishing in the silicon wafer production process. The chemical etching step is necessary to remove any damaged layer caused in the slicing and lapping steps. The typical etching liquor is the acid mixture comprising nitric acid, acetic acid and hydrofluoric acid. The waste acid is treated by a neutralization method with a high alkali cost and balky solid residue. A solvent extraction method is applicable to separate and recover each acid. Acetic acid is first separated from the waste liquor using 2-ethlyhexyl alcohols as an extractant. Then, nitric acid is recovered using TBP (Tri-butyl phosphate). Finally hydrofluoric acid is separated with TBP solvent extraction. The expected recovered acids in this process are 2mol/L acetic acid, 6mol/L nitric acid and 6mol/L hydrofluoric acid. The yields of this process are almost 100% for acetic acid and nitric acid. On the other hand, it is important to recover and reuse the metal values contained in various industrial wastes from a viewpoint of environmental preservation. Most industrial products are made through processes to separate impurities in raw materials, solid and liquid wastes being necessarily discharged as industrial wastes. Chemical methods such as solvent extraction, ion exchange and membrane separation, and physical methods such as heavy media separation, magnetic separation and electrostatic separation are considered as the methods for separation and recovery of the metal values from the wastes. Some examples of the application of solvent extraction to the treatment of wastes such as Ni-Co alloy scrap, Sm-Co alloy scrap, fly ash and flue dust, and liquid wastes such as plating solution, the rinse solution, etching solution and pickling solution are introduced.

Jan 1, 2003

By Takeshi Yoshikawa

For the development of low-cost silicon refining process for solar cells, the present authors have been studying the low temperature refining technique, ?solidification refining of Si with Si-Al melts at 1173 ? 1273K?. In the present work, we have investigated the B removal in that refining, utilizing the segregation effect and also the effect of Ti addition to the melt. Segregation ratio of B between solid Si and Si-Al melt was measured by the temperature gradient zone melting technique and it indicated the B removal fraction would be as much as 90%. Titanium addition to the melt was found to produce the TiB2 precipitation with soluble B in that melt and bring the effective B removal of refined Si to its content of 1ppma.

Jan 1, 2006

By R. Padilla, M. C. Ruiz, R. Villa

"Bismuth is an impurity in copper minerals where it occurs mainly as the mineral bismuthinite (Bi2S3). In smelting of copper minerals, most of the bismuth reports to the white metal, as a result, a substantial amount of bismuth accompanies the copper to the electrorefined cathodes. Thus understanding the behavior of Bi2S3 at high temperatures is crucial to eliminate bismuth before electrorefining. In this paper, some experimental data on the decomposition/volatilization of bismuthinite in nitrogen- oxygen atmospheres is discussed. The results indicated that in nitrogen atmosphere, bismuth volatilization occurs through a fast decomposition of bismuthinite to metallic bismuth and sulfur with subsequent volatilization of bismuth in the range 850-1100 °C. Similarly, in the presence of oxygen, bismuthinite decomposes to bismuth too, followed by oxidation to the non-volatile bismuth trioxide at temperatures higher than 750 °C. Both, temperature and partial pressure of oxygen affect significantly the bismuth volatilization and the oxidation rates.IntroductionCopper sulfide minerals are the major source for the production of metallic copper by pyrometallurgical processes, which are the dominant processes in the production of copper by selectively oxidizing the sulfide sulfur to SO2 and the accompanying iron in the concentrates to iron oxide, which can be conveniently removed as a stable slag.Generally, copper concentrates contain some deleterious minor elements such as arsenic, antimony, bismuth and lead, which are present as sulfides. These elements depending on their concentration may originate problems in the copper smelting processes and they can ultimately lead to a final copper product with unacceptable high levels of impurities.During the treatment of these copper concentrates by smelting, the impurities generally distribute themselves in the condensed and gas phases and they are eliminated mainly through the gas phase [1-3]. Thus, smelter off gases contains substantial amounts of volatilized impurity elements. For example, in the case of bismuth, the estimated distribution of bismuth in flash furnace smelting [2] was 15 % in the matte, 5 % in the slag and 80 % in the gas phase, and recently, for Outokumpu flash smelting Davenport [3] reported the distribution of bismuth as 30-75% in matte, 5-30% in slag and 15 -65 % in the off gas."

Jan 1, 2011

By Doon Gibbs

In this talk, we review highlights of x-ray magnetic scattering studies performed during the last decade, concentrating at the beginning on experiments on the rare earth metal holmium.(1-4) Besides intrinsic interest in the x-ray scattering cross-section and its description, studies of this type are motivated by the possibility that new structural and magnetic properties of rare earth metals might be revealed, and that new techniques may thereby be developed. As a result, interest in x-ray magnetic scattering experiments. has grown rapidly during the last 10 years particularly, with the regular application of synchrotron radiation techniques- Magnetic scattering experiments have by now been performed at most of the x-ray synchrotrons around the world. In addition, insertion .device beamlines dedicated to x-ray magnetic scattering experiments are planned at each of the next-generation storage rings presently under construction in the United States (APS), Europe (ESRF), and Japan (SPRING-8). Generally, the results of x-ray magnetic scattering experiments may be analyzed within two regimes of the incident x-ray energy, namely, in the limit of high x-ray energies, when the incident x-ray energy lies above the excitation energy of any absorption edge, and at resonance, when the incident energy lies near an absorption edge. In the high energy limit, the amplitude for x-ray magnetic scattering has the simple form [L(Q)?A + S(Q)?B](5-7) Here, L(Q) and S(Q) refer to the Fourier 'transforms of the atomic orbital and spin magnetization densities, respectively, and the vectors A and B depend on the incident and scattered wavevectors and on the: incident and scattered polarization vectors. 7) Because the vectors A and B are not identical, the polarization dependence of the orbital contribution to the magnetic cross-section differs from that of the spin contribution. This leads to the possibility that the orbital and spin magnetization densities maybe distinguished, in x-ray scattering experiments. The same distinction is not directly possible by neutron diffraction techniques (in dipole approximation, where the polarization dependence of the orbital contribution is identical to that of the spin contribution), and is important to a fundamental understanding of the electronic structure of magnetic materials. A particular

Jan 1, 1992

By Djalma Souza, Rubén Sánchez, Regina Maria Pinheiro, Carlos Maurício Fontes Vieira, Sergio Neves Monteiro

"This work has for objectives to characterize a waste generated in the form of sludge during the treatment of the effluent of a paper making industry and to evaluate the effect of its incorporation up to 10 wt.% on the properties of a clayey body used for brick production. For the characterization of the waste the following techniques were used: X-ray diffraction, X-ray fluorescence, differential thermal analysis and termogravimetric analysis with mass spectrometry. Specimens were prepared by uniaxial pressing at 20 MPa before firing at 750 °C. The physical and mechanical properties evaluated were: linear shrinkage, water absorption and flexural rupture strength. The results showed that, in agreement with the characteristics of the waste, its recycling into red ceramic can contribute to decrease the consumption of fuel during the firing stage. However, the waste changes the physical and mechanical properties, generating a deleterious effect on the water absorption and flexural rupture strength of the ceramic.IntroductionAccording to the Brazilian Association of Pulp and Paper, in the last 10 years, the global production of paper grew 35%. Brazil produced 8,2 million tons of paper in 2004 and held the position of the seventh largest world manufacturer of pulp, with about 9,4 million tons per year [1]. The pulp and paper industry generates effluents that present problems related to their disposal, even after the treatment. Among the solid wastes generated by this industry, the main waste is the primary sludge from the effluent treatment plant (ETP).After the initial treatment the decanted solids go through a dewatering stage, generating the solid form denominated primary sludge. This sludge resembles a paper paste of dark gray color when humid, and clear gray color when dry. This primary waste is composed basically of kaolin, pulp, traces of chemical substances and water. This waste generated in the pulp and paper industry depends on the characteristics of the process and of the employed techniques. It can vary significantly from one industrial unit to another, even in the case that the final products are similar. Its composition is approximately 60% of kaolin and 40% of pulp, and these percentages can vary in some moments as a function of the process [2,3]."

Jan 1, 2008

By S. W. Ip

Over the years, the importance of surface and interfacial phenomena has been neglected by the copper-nickel industry. As a result, little data on the surface and interfacial tension of the Ni matte and slag system are available in the literature. In view of the scarcity of information in this area, the surface tensions of the Ni-Fe-S system together with the Ni-Fe-S and fayalite type slag system were measured using the sessile drop technique. Drop images were obtained by X-ray radiography. For the Ni-Fe-S system, the results showed that the surface tension of the matte increases with matte grade. The surface tension behavior with changing matte grade showed a slight negative deviation from ideality. This indicated that FeS is slightly surface active in the nickel matte system. Results also indicated that small increase in sulphur content in the matte can decrease the surface tension quite significantly. The measured surface tension of the Ni-Cu-S system showed a linear relationship with the Cu2S content in the matte. The surface tension decreased with Cu2S content. Interfacial tension measurements showed a similar trend. That is, interfacial tension increased with increasing matte grade. The presence of MgO (-1.5%) and A12O3 (-6%) in the slag does not affect the interfacial tension value. Effects of matte surface tension on phenomena such as entrainment of matte in slag and infiltration of matte into refractory pores are discussed. The calculated flotation coefficients indicated that flotation of nickel mattes cannot be avoided by changing the matte grade. Filming of matte on bubbles can occur below a matte grade of about 19% Ni3S2. As for infiltration, refractory bricks containing high Cr2O3 will be easily wetted by matte regardless of matte grade. Therefore, bricks containing high Cr2O3 can easily be infiltrated by liquid matte.

Jan 1, 1993

By Yongyong Gong, Qijie Zhai, Zhichen Zhang, Qixin Li, Zhishuai Xu

"Microstructure of semisolid slurry of Al-4.5wt.%Cu alloy was investigated with pulse magnetooscillation (PMO) treatment, the results showed that the PMO treatment can refine the crystal structures of Al-4.5wt.%Cu alloy significantly. The discharging frequency of PMO had a great effect on the solidified structure transformation of semisolid slurry of Al-4.5wt. %Cu alloy, and the primary a-Al particles become much finer and rounder with an increase of discharging frequency. However, over a certain discharging frequency, the grains of primary a-Al become coarse.IntroductionOver the last decade, a lot of attentions have been paid on metal rheoforming process [1-4], since it has higher mechanical properties of formed components, strength to weight ratio and age hardenablity. Nevertheless, semi-solid forming is always performed at high solid fractions (40%-60%), so it has the limitation of viscosity, a tends to be difficult to pour semisolid slurry into the hole of the shot sleeve. Therefore, a series of novel semi-solid slurry preparation methods and rheoforming techniques have been invented, such as, semisolid vibration treatment [5], rheocasting [6], pulsed magnetic field process [7], annulus electromagnetic stirring [8], via ultrasonic vibration process [9], equal channel angular extrusion (ECAE) process [l0] and straininduced melt activation (SIMA) process [11].The electromagnetic field is characterized by its effective grain refinement, green, convenient manipulation and without contamination of melt. The mechanisms of dendrite was fragmentation by electromagnetic field have also been largely proposed [12-14]. The broken dendrite arms then undergo a coarsening process to provide the globular structures and obtain much finer and rounder a-Al particles. When compared with other external electromagnetic techniques, Pulse Magneto-Oscillation (PMO) has obtained more fuvors, owing to narrower pulse width and much lower energy consumption. Furthermore, the PMO treatment can reach finer grains with shorter time treatment [16, 17]. This work aims to study the effects of different discharging frequency ofPMO treatment on the microstructure transition of the semisolid slurry of Al-4.5 wt.%Cu alloy."

Jan 1, 2014

By Viktor Mukhin

"Among the methods proposed for spent activated carbon regeneration, the most acceptable is, thermal reactivation, because in this case the existing equipment for manufacture of activated carbon can be adapted for this purpose.In order to conduct the process of thermal re-activation of spent activated carbon directly at gold mills, a fullscale drum-type furnace with external electric heating has been developed, i.e. EPV-300 model with a throughput rate of 50 to 120 kg/hour. Its use ensures restoration of the adsorption properties of carbon up to the level of fresh activated carbon with an insignificant (by 0.7%) decrease in strength and with a high (95% to 97%) yield of reactivated carbon.During the recent years, activated powder carbon has been extensively used in flotation processes for treating polymetallic ores at ore treating plants to improve recoveries of main metals (copper, lead, nickel, etc.).Especially large volumes of activated powder carbon are used at the Talnakh concentrator of the Norilsk Mining and Metallurgical Complex in Russia for absorption of residual flotation reagents from recycled water in order to ensure efficient selective separation of minerals with similar physical and chemical properties.IntroductionSorption technology based on active carbons use starts being applied in such an important in the widest sense of the word strategical branch of economics as non-ferrous metallurgy. Thus since the middle ninetieth Russian gold extraction industry began to apply widely the processes of sorption from pulps and solutions by means of high-resistant granulated active carbons. That provided the start of gold ore minefield exploration, increasing of gold extraction from the ore and reducing its loss with the ""tails"" of process. At present more than 40% of Russian gold is extracted with the help of sorption technologies [1].Another field of active carbons application in non-ferrous metallurgy is the processes of non-ferrous ores floatation at ore-mining and processing enterprise. For that purpose powdered (less than l00µm) active carbons are used for providing the effective selection of minerals with similar physicochemical properties. This method not only increases the metal extraction level but provides deeper division of them."

Jan 1, 2008

By Liang Yu, Yuhua Li, Yuanchi Dong

"High alumina slag, with alumina normally more than 15 pct, is encountered with blast furnaces in China because of high alumina/silica ratio in iron ore as well as sinter and high ash content in coke for cost reason. High alumina slag with high viscosity and high liquidus temperature would lead to higher slag volume and thereby, furnace productivity. In the present work, liquidus temperature of high alumina slag, based on Meishan factory, Baosteel China, were investigated. A liquidus temperature model was introduced in the present work based on basic physical chemistry theory and focused on the chemical composition area used in Meishan factory(pct): Al2O3 from 14 to 17.5 and MgO from 8 to 12, so that the blast furnace slag could be designed for optimum blast furnace performance.IntroductionBlast furnace slag composition[1] has very important bearing on its physicochemical characteristics which affects smoothness of operation, slag handling, coke consumption, the degree of desulphurization, hot metal productivity and its quality etc. The slag properties which affect most are liquidus temperature, viscosity, sulphide capacity and alkali capacity. Variation of these slag characteristics with composition and temperature has been a field of active researches as these its great influence on the blast furnace operation. In the early years, most of these studies were carried out over low alumina blast furnace slags with alumina normally less than 15 pct. High alumina slag was first introduced in India because of its high alumina/silica ratio iron ore as well as sinter and high ash content in coke[2]. And then this problem becomes common as higher alumina/silica ratio iron ore imported and used [2-5]. The most important problem caused by high alumina content is liquidus temperature and then viscosity of the slag.Generally speaking those reported works [2-5] investigated a pretty wide range of chemical compositions and then obtained complex model, respectively. In fact, every factory has its own interest because of different resources. For example, the Al2O3 content from 20% to 30% pct was studied in Tata Steel India [2], but it is too high for Baosteel Meishan. A very lower percentage of alumina content, 14-18 % pct, was mainly used."

Jan 1, 2008

By ChuanJie Cai, Zemin Zhuang, Jing Chen, Xuebin Hao, Shaobo Zheng

"Carbon which was used as heating and reducing agent in traditional iron and steel making process at present brought us large amounts of greenhouse gas harmful gases and dust seriously leading to the fog and haze condition. As one of ideal global new energies, Hydrogen has good features such as rich resource, high heat efficiency, cleanness, renewable and transportation. With the commercialization of hydrogen energy, the world energy structure will be changed greatly. Although many scholars have done a lot of researches and long-term exploration on hydrogen metallurgy, researches on the formation of metal iron phase in the process of hydrogen reduction of iron oxides in slag was rarely reported, which had important theoretical significance on the development of hydrogen smelting reduction process. Based on the thermodynamics and kinetics calculation, A laboratory experiment has been designed to research the iron phase formation during hydrogen reduction of iron oxides in the molten slag in this paper. SEM and EDS techniques were also used to observe and analyze the iron morphology. According to detection results, the influence of temperature, reaction time and surface tension on the morphology of the iron phase reduced were showed.IntroductionWith the increasingly severe global warming greenhouse effect, governments are paying more attention to no-carbon and low-carbon energy development and utilization. Hydrogen has received widespread attention around the world, which has rich resources, high thermal efficiency, large energy density, use clean, transportation, storage, renewable etc [1].The development of the hydrogen economy is new competition areas of the world economy for the 21st century. China should assess the situation, and achieve the important strategy of peaceful development as the realization of new industrialization, by establishing a ""hydrogen economy"" industry revolution which replaces fossil energy. The current hydrogen metallurgy process includes hydrogen direct reduction, smelting reduction and direct steelmaking process. Hydrogen plasma hydrogen metallurgy is the use of hydrogen as a reducing agent to replace carbon reductant, to reduce carbon dioxide emissions, and to ensure the sustainable development of ironmaking industry."

Jan 1, 2014

By Jean Igor Margem, Lucas Barbosa de Souza Martins, Frederico Muylaert Margem, Noan Tonini SImonassi, Sérgio Neves Monteiro, Rômulo Leite Loiola

"Fibers of giant bamboo (Dendrocalmus Giganteus) are amongst the strongest lignocellulosic fibers. Although studies have been already performed, limited information exists on the mechanical properties of polymeric composites reinforced with continuous and aligned giant bamboo fibers. This work evaluates the tensile strength of this type of composite. Standard tensile specimens were fabricated with up to 30% of fibers aligned along the specimen's length. The fibers were press molded with a commercial epoxy resin mixed with a hardener and cured for 24 hours at room temperature. The specimens were tested in an Instron machine and the fracture surface analyzed by scanning electron microscopy. The tensile strength increased significantly with the amount of giant bamboo fiber reinforcing the composite. This performance can be associated with the difficult of rupture imposed by the fibers as well as with the type of cracks resulting from the bamboo fiber/epoxy matrix interaction, which prevents rupture to occur.IntroductionDue to growing concern about the ambient impacts from industrial activities, our society is ever more using environmentally friendly materials. In this regard, cellulose-based natural fibers, known as lignocellulosic fibers, become a promising solution. Nowadays, they are being considered as a substitute for synthetic fibers, such as glass fiber, used by the industry on a large scale [1-5]. The application of these natural fibers is also motivated by many advantages like good toughness and less wear of equipment used in the processing of composites. In addition, such composites are environmentally friendly because they are renewable, biodegradable and neutral with respect to C02 emissions, the main responsible for global warming and climate changes. [3,5,6].Lignocellulosic fibers also have some disadvantages in relation to synthetic fibers such as the difficulty of coupling with polymer matrices, due to the hydrophilic character of fiber and the hydrophobic nature of the matrix, as well as dimensional heterogeneity [ 4,5]. This last one is characteristic of the nature of this material and constitutes an obstacle to the use of these fibers in certain projects, especially those that aim high performance. The above mentioned disadvantages are worrisome reasons for the occurrence of reduction in the strengthening capacity, as indicated by the rule of mixtures for composites [7]."

Jan 1, 2013

By T. T. Chen

Secondary copper anodes are generally rich in Sn, Pb, Ni and Sb, but are notably deficient in Se, Te and Ag. In the secondary copper anodes, most of the Ni, virtually all of the Ag, slightly more than one-fifth of the Pb, about one-third of the As and Sb, and approximately one-tenth of the Sn are in solid solution in the copper. The remaining impurity contents occur as 1-5 µm grain-boundary inclusions in the anodes, and these are mainly Cu2O, SnO2, Cu-Pb-As-Sb-Bi oxide, Pb-Sb oxide, Sn-Ni-Zn oxide, Cu-Sn-Ni oxide, Cu-Sb-Ni oxide (Kupferglimmer) and trace Cu2(Se,Te). Barium sulphate, which originates from the mold wash used in casting, is also present in the anodes. During electrorefining, the BaSO4, SnO2, Pb-Sb oxide, Sn-Ni-Zn oxide, Cu-Sn-Ni oxide and Cu- Sb-Ni oxide inclusions are liberated and accumulate in the slimes layer. Solid solution Ni dissolves and the Ni accumulates in the electrolyte. Solid solution Sn and Pb dissolve, but partly reprecipitate as Sn arsenate and PbSO4, respectively. Solid solution Ag dissolves but rapidly reacts to form Ag2(Se,Te), Ag powder, Ag-bearing Cu2O, (Cu,Ag)SO4 or a complex oxidate phase. Partial dissolution of the Cu-Pb-As-Sb-Bi oxide particles takes place; the Pb component is converted to PbSO4, whereas Cu, As, Sb and Bi dissolve. The reacted particles retain the morphology of the original Cu-Pb-As- Sb-Bi oxide phase. Some of the solubilized As, Sb and Bi remains in solution, but much reprecipitates as SbAsO4, As-Sb-Bi oxide, and as a poorly defined oxidate phase which consists mostly of Cu-Ag-Pb arsenate-sulphate. The high Sn contents of secondary copper anodes do not seem to affect the behaviour of the anodes during electrorefining.

Jan 1, 1999

By William J. Mallio

Substantial differences between in situ and conventional technology require that in situ ore grade be established for deposit as distinct from the total contained metal value. Establishing an in situ ore grade involves determining the fraction' of the contained metal that can be leached by the fluid. This depends on the proportion of the ore minerals that occur on fluid flow paths as defined by the permeability distribution. Mechanisms involved in the in situ mining of sulfides are: oxidation of the sulfur, solution of the metals, complexing of the released metals, and a transport to a recovery point. Metal ions may be delayed or lost due to inefficiencies in these pro-cess steps or by reactions of the metal ions in solution with the rock. These reactions can involve precipitation of new phases, exchange of the metals of the interest with Ca or Na in clays or zeolites, retention of metals in oxidized mineral grains, or secondary enrichment of other sulfides along the paths of the solution flow. The efficiency of solution of metals and potential loss or delay mechanisms are controlled by local equilibria (the Eh, pH conditions) present in different parts of the ore zone. Permeability distribution in the rock mass and the coincidence of ore minerais with flow channels must be determined before a deposit can be judged suitable for in situ mining. Laboratory studies indicate that the natural permeability system is dependent on the degree of cementation of veins by late generation hydrothermal activities. The major conclusions of the study are:, 1. Deposit selection is critical; suitable deposit types include deep lying sedimentary deposits, selected zones of porphyry systems and vein controlled hydrothermal deposits; 2. Adequate laboratory and geochemical analyses should be undertaken through quantitative petrographic study and permeability mapping; and 3. Economic incentives for in situ mining must consider limitations of recovery caused by inefficiencies in dissolution and transport associated with particular deposits.

Jan 1, 1981

By Selvin Yesilay, Guray Kaya, Bekir Karasu, Asli Cakir

"In this investigation, the wastes of Eti Maden Kirka Boron Company of Turkiye were evaluated in the production of diopside and anorthite-based glass-ceramic glazes suitable for porcelain tiles fast and single-fired under industrial conditions. First of all, high wear resistant frits were produced with the use of concentrator and derivative borax wastes. Second of all, pre-engobed porcelain tile bodies were coated with the standard and newly produced frit-based glazes and industrial fast single-firing was employed. Final products were undergone to the certain standard tests to determine their Vickers hardness, wear resistance, thermal expansion coefficient values, gloss and coloring parameters. The micro-structures and phase formations of the fired glazes were also studied. Consequently, it was confirmed that the utilization of borax solid wastes in fast single-fired porcelain tile glass-ceramic glazes is possible. Introduction Porcelain tiles were introduced at the end of 1980s by Friandre, one of the leading Italian porcelain manufacturers. The American National Standard Specifications for Ceramic Tile defines porcelain tiles as: dense, smooth, impervious (with water absorption value less than 0.5 %) and stain resistant [1]. The excellent technical performances for ceramic tiles, such as mechanical, wear, frost and chemical resistance that make their use possible in indoor and outdoor building applications [2-3]. In the last decade, the growth rate of the global production of porcelain tiles increased more than those of other ceramic products; in fact, the technical properties of porcelain tile, coupled with even more improved aesthetic appearance, gave it a prominent role on the tile market [2]. Glass-ceramics are composed materials of one or more crystalline phases immersed in a residual glassy phase [4-5]. Glass-ceramic technology is based on controlled nucleation and crystallization of bulk glass [6]. The concepts of controlled crystallization of glass designate the separation of a crystalline phase from the parent glass in the form of tiny crystals. Their growth rate and final size are controlled by a suitable heat treatment [7]."

Jan 1, 2008

By Veronica Escobar

This paper presents results from a two month pilot evaluation of EMEW® technology at CODELCO Radomiro Tomic, in Chile. A prime focus in the test programme was to assess the technology?s capabilities to recover high quality copper from the Radomiro Tomic electrowinning tank house bleed stream. The EMEW® cell developed by Electrometals Technologies Ltd. tolerates substantially higher levels of contaminants than those found in conventional tankhouse, operating at high current densities while maintaining high cathode copper quality all the way down to low copper concentrations. To maintain high copper purity in a copper electrowinning (or electro-refining) tank house, a continuous bleed of solution must be taken from the tank house inventory to prevent build-up of contaminants, and resulting degradation in cathode quality. In an SX-EW operation, this bleed stream is normally recycled back to the solvent extraction circuit, but is occasionally sent to the raffinate pond to re-enter the leach circuit. Return of the bleed stream to the solvent extraction circuit creates a continually recycling load of copper in solution, which may reduce overall plant capacity and expansion potential. Return to the leach circuit has a similar effect, and methods to reduce its impact are always under consideration. The use of the EMEW® technology allows for direct and efficient recovery of near 100% of the contained copper instead of recycling. Tests were run at ambient temperature on bleed electrolyte using current densities which varied between 250 and 1100 amps per square meter, with copper concentrations between 38 and 1 g/l. A profile of maximum allowable current density with respect to concentration was developed, showing that high grade copper can be obtained at all levels of concentrations tested, by choosing an appropriate current density and electrolyte flow rate. The results of this programme show that the recirculating bleed electrolyte from an SX-EW operation can be converted into an expansion in copper production at a comparatively low investment cost.

Jan 1, 2003

By Kunihiko Takeda, Kimio Imaizumi, Tsuyoshi Arai

"The study on the preparation of mono-dispersed liquid droplet was performed using ultrasonic as one of the steps of producing the perfectly mono-dispersed particle. The ultrasonic system was a 33.6kHz ultrasonic generator, an amplifier, an electric distortion element, and a bolted Langevin type horn installed in .a cell. For the first time, a liquid pillar under a nozzle of the cell ·was stably formed. Then, dense and coarse parts were alternatively constructed by oscillating the wavelength of the ultrasonic.· The diameter of those liquid droplets were found to be· perfectly uniform, therefore, it was measured by ""multiplex photography"" using a synchronized stroboscope with the ultrasonic.- From the results, more than 30,000 of perfectly uniform liquid droplets in 1 second were observed by this method.IntroductionRecently, research on the control of physical form is done in various fields of industry. Some examples are the processing technology of the minute compound material of micro-machines and integrated circuits, and the form control of molecule size like catalysts. There is a need for such material to take on various forms in correspondence to its use. ""Form control"" as used in this study will indicate ""research on physical chemistry factors which determine the size of the material"" and will refer to the contour uniformity of comparatively little particles. A well-known method of preparing particles is to spout a mist of liquid and slurry from a nozzle l) 2). Particles for metals, catalysts and food have been prepared by this method. In this case, although an approximate particle diameter can be decided by controlling the nozzle diameter and the violent outflow velocity, it is not easy to completely control ·the contour and to prepare a particle with uniform diameter. ·However, the preparation of perfectly uniform particles is necessary for solders for the adhesion of electronic wiring 3), ion exchange resins4), catalysts and so on. Large quantities of fine particles and super-fine particles are generated when manufactured in the usual way. Large quantities of these fine· particles and super-fine particles have polluted the internal and external' environments of factories. The products yield' ·decreases, also. From such a background, this study examines the preparation of perfectly uniform particles that could be· collected -100% as products. Recently, NASA has succeeded in the preparation of perfectly uniform particles in zero gravity 5). But the preparation of 'perfectly uniform particles by this method is difficult, and it can not be used in general industry"

Jan 1, 2000

By Thomas F. Hagelien, Stein Tore Johansen, Svend Graadahl

"The dross appearing at the surface of an aluminium melt consists, in addition to aluminium, of mainly oxide films but also other non metallic inclusions. The inclusion particles are often poorly wetted by the metal and accumulate at the metal surface. However, in impeller stirred reactors for melt refining stirring may be exceedingly strong and inclusions accumulated at the metal surface may be entrained into the bulk metal. Concerning inclusion removal, such effects may deteriorate the effectiveness of melt refining.In this paper we investigate the surface entrainment of buoyant particles in a water model of an impeller stirred refining reactor. Under varying operating conditions the particle concentration in the bulk liquid is measured by laser light attenuation. The observed entrainment of particles is explained theoretically and metallurgical consequences of the findings are discussed.IntroductionIn the modern cast house continuos metal refining and casting is well established. One of the most distinct advances in metal refining has been the introduction of degassers which introduce bubbles into the metal. The bubbles act to remove dissolved elements together with nonmetallic inclusions. In the most efficient degassers stirring by different kind of rotors is applied to increase mass transfer and inclusion removal. However, it has been known from experience in the cast house that for violent stirring the concentration of some types of inclusions may increase from inlet to outlet of the reactor. This phenomenon has so far been attributed to production of dross in the reactor due to oxidation of metal. Due to removal of inclusions by bubbles the dross layer inside the reactor must be expected to increase in thickness by time. The removed inclusions and produced oxides due to strong stirring is removed at regular interval by the operators of the degasser. However, a fundamental understanding of the phenomena which take place in and below the dross layer is lacking. In the present work we add buoyant particles to the surface of a refining reactor and investigate how these particles may be entrained and dispersed into the liquid depending on the flow conditions. Similar investigations for gas stirred ladles have been performed by Taniguchi et al [1] who found that below a critical gas flow rate all particles are trapped at the surface. Above the critical gas flowrate the surface velocity are sufficiently high to entrain the particles. In this situation it looks like all particles are ready for the melt and a balance between terminal velocity and turbulent dispersion determine the concentration in the liquid."

Jan 1, 1999

By Philip Thompson

"Carefully planned laboratory test programs provide valuable data regarding the amenability of low grade gold ores to heap leaching. The most common laboratory test is the column leach test. The overwhelming problem associated with this type of test is the limit on the test column height. Most laboratories use a three (3) meter (10 foot) high column as a standard test due to building ceiling limitations, sample size limitations, etc. This paper presents a case study in which an ore sample was tested in a 1.5 meter, a three meter, and a six meter high column to determine the effect of column height on the test results. Other important factors such as sample preparation protocol, preliminary bottle roll testing to determine appropriate crush size, column diameter requirements, and leach solution analyses, are also discussed.IntroductionColumn leach testing has been used for years by many laboratories to determine the amenability of low grade precious metals bearing ores to heap leaching. However, the test work can be compromised by poor planning, misinterpretation of results, and extrapolation of data beyond the reasonable boundaries of the experiment. Preliminary test work should be performed prior to column testing. This preliminary work provides valuable information regarding the response of the ore to cyanidation and aids in the design of the column tests.The sample should be screened into various size fractions prior to testing. The fractions are assayed to determine the gold content of each size fraction and of the overall sample. The most valuable preliminary test is the bottle roll cyanidation test which is usually performed on five kilograms of coarse sample in a large rolling bottle which can accept material up to 50 millimeters top size. The residue from this test is screened at different sizes to determine the distribution of unleached gold in the residue. Comparison of the gold distribution in the leach residue with the distribution of gold in the feed at the same size intervals provides an indication of the appropriate crush size for the sample. The overall gold extraction from the sample at the crush size tested is also determined from these data. Lime and cyanide requirements can also be estimated from this test. The viscosity of the bottle roll pulp and the size distribution of the feed and leach residue can also suggest whether agglomeration of the ore will be required prior to column testing. Ores which contain significant amounts of clays (greater than 5 percent) will generally require agglomeration to prevent plugging of the test column."

Jan 1, 1997

By Tatiana Pereira Moreno, Priscilla Aki Mori de Hanashiro, Viviane Tavares de Moraes, Denise Crocce Romano Espinosa, Hugo Hashimoto

"Nowadays, End-of-Life (EoL) Liquid Crystal Displays (LCDs) are traditionally disposed in landfills. The increasing access to LCD technology over the last years by Brazilian consumers has intensified LCD' s disposal as an environmental and economic issue. This study aims to characterize used LCDs to identify the main components for recycling. Characterization was performed through scrap disassembly and its components were identified, separated, and weighted. LCDs were disassembled and the following divisions were applied: screen, metal frame, polymeric frame, polymeric sheets and electronic part. Some techniques were used to determine the concentration of Indium in the LCD, the glass/plastic ratio and the different kinds of polymers that compose the screen. The techniques used for characterization included inductively coupled plasma optical emission spectrometry (ICP-OES), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). This method, when applied to a wide range of LCDs, can allow the development or improvement of an EoL management of LCD.IntroductionWaste Electrical Electronic Equipments (WEEEs) are waste from discarded equipment, such as computers, monitors and cellphones [1]. Over the past years, treatment of WEEE has been emphasized. It occurs due to the technology's advancement that leads to an even larger increase of WEEES [2].Among WEEEs, there are the liquid crystal displays (LCD). LCD technology is applied in cell phones, tablets, computers and monitors. Nowadays, it's the most well known technology when it refers to monitors, due to its advantages over the Cathode Ray Tube (CRT) technology. Some of them are energy saving, smaller size and no radiation emission [3].This feature in the LCD's global market along with the speed at which electronic equipment becomes obsolete affects society economically and ambiently.This issue becomes even more serious when considering the final destination of the liquid crystal displays. LCDs are lead to landfills as other WEEEs. Besides the different materials long degradation time, the environment is damaged by the disposal of the potentially reusable and hazardous materials [ 4]."

Jan 1, 2014

By Wen-Ming Chien, Vamsi Krishna Kamisetty, Amrita Mishra, Ivan Gantan, Prathyusha Mekala, Dhanesh Chandra

"The phase equilibrium and characterization studies by using high temperature X-ray diffraction (XRD) and differential scanning calorimetric (DSC) methods have been performed for binary organic thermal energy storage materials. The organic thermal energy storage materials undergo a solid-solid state phase transition before melting which stores large amounts of thermal energy. Two materials [tris(hydroxymethyl)aminomethane(TRIS) and 2-Amino-2-methyl-l, 3- propanediol(AMPL)] were used for this study. Binary samples of AMPL-TRIS were prepared to perform high temperature XRD characterization and DSC studies and the binary AMPL-TRIS phase diagram was developed. The high temperature solid-state phases of AMPL and TRIS were characterized as a disordered BCC structure. It was found there is virtually no solubility of TRIS in AMPL or vice versa below -75 °C. The maximum solubility of TRIS in AMPL is 11% TRIS at 75 °C. The eutectoid transformation was shown at 19%TRIS-81%AMPL composition and at a temperature of 75°C. Lattice expansion calculations on single phase of TRIS and AMPL have been performed.IntroductionThermal energy storage materials can store a large amount of heat due to the presence of thermal transitions from the orientationally ordered to disordered phases occurring before melting. These molecules (such as amine and alcohol derivatives of neopentane) can reorient as a whole about the central carbon atom to form orientationally disordered crystals (ODIC) and their spherical shape makes them reorient relatively easier. Thermal energy storage materials are becoming increasingly important as a renewable energy resource. These molecules undergo large changes in enthalpies at solid-solid transitions. The presence of these compounds with large enthalpy changes are identified as potential thermal energy materials and some of die applications are solar cell systems [1-3]. Binary mixtures have been found as a way to adjust the transition properties in addition to pure compounds [4]. Tris(hydroxyrnethyl)aminomethane (TRIS, C(CH2OH)3NH2) and AMPL, CH3C(CH2OH)2NH2) are two important thermal energy storage materials."

Jan 1, 2012