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By E. Salinas R.

This work is related with a whole characterization of cantera stone, to establish its characteristics that can give it an additional value for the reuse and reutilization of dust, slurries and small pieces of stone which can be treated as wastes. The obtained results reflects that the residues studied can be used as substitutes of feldspars in the production of pieces of ceramic, and also in the elaboration of paints for the same pieces according to the mixes that can be made with the variation of Na2O, CaO and K2O. According to the humidity proofs and specific gravity done, this material can be proposed as a soil improver into hydroponics systems, leading so an important alternative for food production in zones leaking of water. In the same way, it was found the possibility of use this material as a seal 3A in processes of asphalting of roads, highways and streets.

Jan 1, 2009

By Patricia Negrini Siqueira

Abstract. Polymers are susceptible to changes in their chemical structures that affect their mechanical properties under weather condition. Exposure of plastics to UV radiation causes a loss in their mechanical properties and/or change in appearance, including reduced ductility, color changes, yellowing and cracking. Today, there are several additive systems (light stabilizers) developed to work according to resin, final application, type of cultivation, and other characteristics. This study evaluates the different additive systems (Hindered Amine Light Stabilizer - HALS, nano calcium carbonate - NPCC, nZnO and nTiO2), applied 0.75% (in weight) in linear low density polyethylene (LLDPE). The samples were mixed by high rotation homogenizer and extrusion. Later, the samples were molded by injection and aged in QUV-B simulating 6 months of exposure to weather. Tests of FT-IR and tensile strength comparing to the non-aged samples were carried out in order to evaluate the performance of several additive systems.

Jan 1, 2015

By P. G. McCormick

The refining of rare earth metals by the direct solid state reduction of their respective chlorides during mechanical alloying has been studied. Erbium and gadolinium were synthesised by milling their respective chlorides with calcium. The mechanical alloying of SmC13 with calcium resulted in partial reduction of SmC12. Examination of the milled powders using X- ray diffraction and analytical electron microscopy has enabled characterisation of product structure and morphology. The synthesis of Fe17Nd2 by the mechanical alloying of NdC13 and Fe with calcium has also been studied. The Fe17Nd2 phase forms during heat treatment of the mechanically alloyed powder.

Jan 1, 1992

By F. J. Tavera

The column flotation technology, at first developed for application in mineral dressing, has received special attention in processing of non-mineral dispersions as a result of its low cost, high efficiency and relatively simple operation. This paper presents the results from the operation of a laboratory flotation column for the separation of vegetable oil and soap from aqueous industrial effluents, The flotation system was operated under continuous countercurrent conditions without and with additions of a cationic collector. The experiments show that it is possible to separate about 80% of the organic phase in a rougher flotation stage. These results suggest that the recovery of the organic phase is highly dependant on the dispersion characteristics (i.e. bubble size, gas holdup and bubble surface area flux) and the existing an optimum bubble size from which either smaller or larger, the recovery of the organic decreases.

Jan 1, 2003

By Jun Sugiyama, Hiroyuki Sano, Toshiharu Fujisawa, Hideki Takeuchi, Chikabiuni Yamauchi

"The solid .state electrotransport (SSE) is one of the most promising methods for the elimination of gaseous impurities from chemically active metals, such as rare earth metals. . In the present work, the SSE process was applied for the oxygen removal from praseodymium. The SSE factors, such as effective valence, were measured under the various temperatures, electric field intensities and initial oxygen contents, and the effects of those conditions on the SSE process were discussed. Furthermore, the solubility of oxygen in .solid praseodyillium was also measured·, by using the SSE method and metal-oxide equilibrium method.IntroductionWhen a direct current is passed through a solid alloy, not only electrons but also solute atoms are transported as charge carriers toward the anode or cathode. This phenomenon is referred to as an electrotransport or electromigration. The solid state electrotransport (SSE) is the application technique, based on this principle, to the pUrification of the solid metallic materials.Rare earth metals are used for various functional materials, such as magnetic, optical or electronic materials, therefore their high purity metals are required [l ,2]. However, rare earth metals are chemically active and have a strong affinity with gaseous elements (e.g. oxygen, nitrogen, hydrogen and carbon). In many cases, eliminating operations of gaseous elements have not been always made commercially, because these impurity elements could not be eliminated by usual treatments applied to the purification of ·common metals. As an alternative method, authors have proposed the· application of the SSE process to the elimination of gaseous impurities from rare earth metals. Investigations have been carried out on the yttrium-oxygen and neodymium-oxygen systems and the results were already reported[3,4]."

Jan 1, 2000

By Bin Zhu, Mingmei Zhu, Hong Zhou, Xiaofei Dou, Bin Xie, Yu Wang, Tiancheng Lin

In this study, the formation of 2CaO·SiO2 and 3CaO·P2O5 solid solution (nC2S-C3P) in hot metal dephosphorization process is discussed. The variations of CaO and SiO2 mass, both in nC2S-C3P solid solution phase and liquid slag phase with increasing P2O5 mass in CaO-SiO2-FetO-P2O5 slags were calculated using Factsage software. CaO-SiO2-FeOt-P2O5 slag containing up to 18 % P2O5 was melted at 1823 K then cooled to 1673 K. The contents of CaO and SiO2 both in the solid solution phase and liquid slag phase of quenched samples were observed and analyzed by SEM/EDS. Both the calculated and experimental results show that the contents of CaO and SiO2 in the solid solution phase decreased, just opposite in the liquid slag phase, with increasing P2O5 content in the slags. Formation mechanism of nC2S-C3P solid solution in the slags was derived based on the ionic structure theory of molten slag. The SiO4 4- in the nC2S-C3P solid solution can be replaced by PO4 3- in the liquid phase resulting in the increasing of free Ca2+ and SiO4 4- in liquid phase.

Jan 1, 2015

By Mingmei Zhu, Lang Hu, Yu Wang, Hongpo Wang, Congjing Zhang

Magnetic field has a great effect on the crystallization behavior of mold flux and properties of the flux film between mold and strand, on which the surface quality of strand was deeply depended in continuous casting process. Therefore, studying the change law of the crystallization properties of mold flux in magnetic field is of great significant. In the present work, based on intensity of the applied magnetic field with the range from 0mT to 60mT, the crystallization ratio, crystal size and mineralogical phases of the flux film were discussed. The results show that crystallization ratio increases with the increasing magnetic field intensity, and the crystal size becomes bigger at the same time. The magnetic field promotes the crystallization ratio and growth speed of the crystallized grains of mold flux. However, magnetic field doesn’t change types of the mineralogical phases.

Jan 1, 2015

By Chen Chen, Wang Yanze, Hong Xin

Furnace superalloy was applied in harsh environment within the erosion of high temperature and oxidizing atmosphere. With plasma powder surfacing technology, iron-based alloy powder was sprayed on the surface of 310S stainless steel to form oxidation layer that increases the oxidation resistance and reduces the cost of materials. With optimum technological parameters, in this paper, oxidation test of 100 hours on iron-based cladding alloy and furnace alloy were carried out at 1200 . The technique of XRF, XRD and EDS were used to characterize composition, oxide morphologies and surface mechanical properties. The results showed that Element composition of cladding layer formed by Plasma powder surfacing was well distributed. Its oxidation weight gain rate of 100 hours was 0.4552g/m2h, belonged to antioxidant level. The oxidation weight gain rate of furnace alloy was 1.4617g/m2h, belonged time-antioxidant level. And on the mechanical comparison test, surfacing alloy is relatively excellent than furnace alloy.

Jan 1, 2016

By Zhang Chuanfu, Li Shixiong

"In the electrolysis electrodeposition or electroplating of aqueous solution of copper, lead, zinc, nickel, manganese etc, with the increase in cathodic over potential the reducing rate of metal and the cathodic current efficiency increases and the deposit becomes more compact and smooth. According to this principle, a method and equipment of the auto-control of electrolyte quality is invented. The industrial application shows that this method turns the experienced operation into auto-control. The quality and quantity of metal is improved greatly and the consumption of electric energy is reduced.In the electrolysis, electrodeposition or electroplating of aqueous solution of copper, lead, zinc, nickel, manganese etc, usually organic additives are added according to the state of cathodic deposit according to experience. This traditional and experienced operation, often lead to that the quality of additive is not optimum which affects the quality and quantity of metal and increases the consumption of electric energy. To counter the controlling problem of the quantity of additive, the authors have invented a corresponding equipment of the auto-control of electrolyte quality [1], it has found application in industrial practice."

Jan 1, 2000

By Matsufumi Takaya, Yukihiro Sakamoto

"Electric field emission properties from CVD diamond fabricated using pulse-modulated microwave plasma CVD were studied. Diamond was synthesized by microwave plasma CVD apparatus equipped with a pulse-modulated microwave power supply. Pulse conditions were varied from 1 to 10 seconds for pulse periods and from 0.1 to lHz for pulse frequency either. Surface morphologies of the deposits were differed by pulse frequency and duty cycle. As a result, FE properties prepared by different pulse duty cycle were different from continuous film which synthesized using continuous microwave significantly. Highest current density was obtained from the uneven morphology diamond film prepared at 17.5% pulse duty cycle.FE properties of the CVD diamond were depended on surface morphologies that related to the pulse conditions.1. IntroductionDiamond has excellent physical and chemical properties as an industrial material. Especially, hydrogen terminated diamond had the negative electron affinity (NEA) 1) and CVD diamond has this NEA property either as deposited 2). So the electron emission source to the FED is expected as one of this application of CVD diamond as cold cathode of electric devices. We studied on FE properties of various CVD diamond, pulse microwave plasma CVD diamond showed better property than those of other CVD diamond 3).This report studied on· the effect of the duty-cycle of pulse modulate microwave condition on FE properties of the diamond fabricated by pulse modulated microwave plasma CVD."

Jan 1, 2000

By N. Choi

The distribution behavior of selenium and tellurium in nickel sulfide smelting was investigated in the temperature range of 1250-1300 °C under an inert gas atmosphere and various oxygen partial pressures. The distribution coefficients of selenium and tellurium between nickel-copper-iron matte and silica-saturated iron silicate slag were detennined in terms of matte and slag compositions, temperature, and oxygen partial pressure. The effect of slag additives such as CaO, MgO, and Ah03 on the distribution coefficients of those elements was also investigated. It was observed that the distribution coefficients of selenium and tellurium increased with increasing matte grade and temperature. The solubility of selenium and tellurium in the slag decreased with increasing the partial pressure of oxygen within the range investigated in this study. The distribution coefficients of selenium and tellurium increased with the amount of CaO and MgO. Tellurium distribution coefficients also increased by the addition of Ah03. Meanwhile, the addition of Alz03 decreased the distribution coefficients of selenium at high matte grade.

Jan 1, 1996

By K. Noda

Tamano Smelter of Hibi Kyodo Smelting Co., Ltd. started its operation adopting the Flash Smelting Furnace with Furnace Electrodes (FSFE). Thereafter, it developed a coke combustion technology based on C() concentration control, which made possible a low cost and high productivity operation without using electrodes. However, increase of treated concentrates and upgrading of matte grade for production expansion started to cause difficulties in operation control with then existing operation control system. This paper outlines recent improvements for stable operation of the Tamano Type Flash Smelting Furnace (T-FSF), such as computer aided operation guide system.

Jan 1, 2001

By Guo Chang Jiang

In order to improve the IIAZ toughness of X-60 pipe steel, the intragranular ferrite plate (IFP) technology was used. The characteristics of IFP is claimed to be much fine ferrite plates appear inside the original austenite grains. By means of suitable Re, Zr, Ti additions in a bath with a higher initial oxygen potential, a good control of the peak temperature and the cooling rate during welding simulation, one can get a %IFP in volume over 50%, and the toughness gets up from 55 J to 160 J. It was found that the inclusions most effective in nucleating IFP are some deformable complex silicates which either entrap Re, Zr, Ti oxides or contain these elements. The greater the number of the evenly distributed and effectively nucleating inclusions, the more the %IFP in volume, and the finer the microstructure of the HAZ, so the better the relevant toughness. Generally, these silicates bahave as fine spheres along a line. The present authors revealed that these fine spheres result from the remelting of the shuttle- like silicates due to heating in the process of welding simulation. These silicates used to get a higher sulphur capacity, so MnS deposits might be observed on the periphery of the silicates. IFP was proved to be directly rooted in the [Mn] depleting zone which locates beside MnS deposits.

Jan 1, 1997

By T. Mason, R. Macko

Electroless nickel (EN) coatings are widely used in the manufacture of automotive parts, providing uniform coating, corrosion protection, wear resistance and lubrication. In contrast to EN plating benefits, the disposal and treatment of waste solutions can cause many difficulties. The use of electrochemical treatment technology greatly improves _the operation of the main wastewater treatment process and reduces operation costs. A new, state-of-the-art job shop in the Chicago area, which provides EN plating for the automotive industry, has installed a large separated electrolytic cell for the treatment of spent EN solution (from dumps and wastewater). The waste/wastewater is handled by the separated electrolytic cell, batch treatment system, filter press and neutralization station. The implementation of modem electrolytic technology and auxilliary equipment provides an effective waste treatment process that meets environmental compliance criteria.

Jan 1, 2000

By Laszlo Kadar, J. D. Lavers

"In the continuous casting of aluminum killed steel, the tundish nozzle often experiences clogging problems. Water model studies have shown that the clogging problem is dependent on the flow pattern in the nozzle entry region. In particular, the flow can separate at the entrance to the nozzle, leading to the development of a recirculation region. Although a nozzle can be designed such that no recirculation develops, even a small misalignment from the vertical positioning of the nozzle may render the design ineffective.To reduce the possibility of nozzle clogging, the recirculation zone must be reduced or eliminated. This may be achieved by moving the fluid downwards or raising the turbulence level in the separation region. In the case of a tundish nozzle, it is proposed that this can be achieved by using electromagnetic forces.To generate the required electromagnetic force, two systems are considered. The first is based on injecting a DC current; the second by using electromagnetic induction. Both methods are described in this paper. Order of magnitude calculations are provided to illustrate that both methods are essentially feasible. The performance of each method in terms of modifying the turbulent flow characteristics in the nozzle entry region is then examined using a numerical model. It is shown that both methods can greatly reduce the recirculation zone. A cylindrical nozzle was chosen for the model studies since it represents a worst case situation.On the basis of the model studies, it can be concluded that whereas both of the proposed methods have the potential to reduce the troublesome recirculation zone, the induction method appears to be simpler in terms of practical implementation."

Jan 1, 1999

By Jafar Safarian, Merete Tangstad, Leiv Kolbeinsen

"Silicon and its binary alloys have several applications in metallurgical, chemical, photovoltaic and semiconductor industries. Silicon goes to its liquid state within its production, refining and when it is alloyed with other elements. Therefore, the characterization of silicon melts thermodynamics is important and useful. The liquidus and activities in several silicon binary systems have been recently calculated by the application of two liquidus constants, which were established using the experimentally determined liquidus data. In the present study, the thermodynamic properties of six silicon binary melts, which are simple eutectics, are calculated by analytical approaches. In this case, the changes in the partial and integral Gibbs free energies and enthalpies of mixing are calculated and compared with the experimental data in literature. The enthalpies are calculated by two methods and the calculation results are compared to the data from the literature. It is shown that thermodynamic properties of silicon binary melts can be accurately predicted without the use of complicated thermodynamic software.IntroductionSilicon and its alloys have several industrial applications. Silicon is used for making aluminium-silicon alloys to produce cast parts, mainly for automotive industry. Silicon in the form of ferro-silicon is used to deoxidize and alloy steel and cast iron. The photovoltaic (PV) industry has had a rapid growth in the recent years and silicon is the dominant material used for the fabrication of solar cells. Silicon is primarily produced through carbothermic reduction of quartz in electric arc furnaces and the produced metallurgical grade silicon (MG-Si) contains around 1 wt% impurities. It is further refined to produce solar grade silicon (SoG-Si) with above 99.9999 wt% Si to fulfil the chemical requirement for PV application. Since molten silicon is processed all along the metallurgical route, obtaining fundamental thermodynamics knowledge about silicon melts is valuable for the related industries."

Jan 1, 2012

By Sheng-li Wu, Guo-liang Zhang, Bo Su

The mineralogical characteristics of iron ores can influence their high temperature sintering performance. In this study, eight iron ore samples from Brazil, Australia, and South Africa were characterized by their chemical composition, mineral types, particle morphology, and gangue dispersity. Meanwhile the influence rules between the mineralogical characteristics and the high temperature characteristics were evaluated and analyzed. The results showed that the effect of SiO2 on assimilation characteristic of iron ores was relatively complex, Al2O3 and LOI of iron ores had negative correlation with assimilation temperature of iron ores, the dense slab-flaky mineral granule restrained to the assimilation characteristics of iron ores; liquid phase of iron ores with high SiO2 content and low Al2O3 content had high fluidity, and the higher dispersity of gangue minerals in iron ores was good to the fluidity of liquid phase.

Jan 1, 2015

By W. W. Albrecht

I. Introduction Refractory metals like tungsten, molybdenum, rhenium, tantalum and niobium and their compounds are essential ingredients of our modern technology. Especially in purified form, they are used in special alloys, electronics, optics and ceramics. The processing route from raw material to high purity refractory metals and their compounds includes, as a prime option, the following steps: - dissolution of raw materials. - liquid liquid extraction. - precipitation of high purity intermediate compounds. - calcination/reduction to high purity oxides/metals. Especially in the first three steps, major amounts of chemicals like acids or sodium hydroxide are used and, as by-products, substantial quantities of residues and effluents are generated. The impact of environmental regulations on these by-products and the attempt to reduce or minimize the amount of residues and effluents produced will be discussed in this presentation using Ta/Nb chemistry as the example. The basis of our considerations will be the way these by-products are handled at HCST, a major, and in some cases, the biggest producer of refractory metals (tungsten, molybdenum, rhenium, tantalum, and niobium).

Jan 1, 1992

By R. C. Hubli

A panial equilibrium model? to simulate the dissolution of millerite (NiS) in aqueous solutions containing copper(II) chloride as the oxidizing species has been developed. The predominant copper(I) and copper(II) species are CuQ3 and CUO2 respectively. The model computes the initial concentrations of the species present in the aqueous phase under the specified input conditions, prior to the simulation of dissolution. During the dissolution of millerite, nickel enters the leach liquor as NiH and it has been found that the H+ decreases as a function of NiS dissolution. The simulation has been accomplished under conditions prevailing during actual dissolution, with only one mineral undergoing dissolution. The model can be applied for the simulation of co-dissolution of two or more sulfides. Under the given conditions, the precipitation of Cu1(OH»)O is negligible but loss of Cu(1l) could be significant if the initial H+ is lower than 0.03 M. The results of the simulation compare favorably with experimental observations.

Jan 1, 1996

By D. P. Cook, Jr. Jones, J. W. Evans

"It is well understood that the flow of liquid metal in the mold region of the caster can have a notable effect on the overall solidification behavior in aluminum casting. Previously our group has characterized the flow in this region in a water model, using particle imaging velocimetry. The flow is significantly effected by the specifics of the metal delivery system, i.e. size, geometry, used during the cast. Recently, a time-averaged 3D numerical model of the nozzle, combo bag and sump region has been developed and its validity has been tested against experimental data. Cases were run for different sized combo bags as well as bags that have been blocked. The results show satisfactory agreement between the physical and mathematical models.IntroductionFluid flow in the head of an electromagnetic (EM) and direct chill (DC) ingots has been shown to effect many important operational parameters in casting such as superheat removal, macrosegregation, and hot cracking. In most cases, the momentum from the nozzle is diverted through a delivery system, termed a bag, before entering the mold region. The specific geometries of the bags vary widely from operator to operator suggesting that there is still some question as to the optimum design. Several studies [1-4] have been carried out to understand the influence of the bag design on the solidification behavior in aluminum casters. However, few studies have included numerical prediction with experimental verification. Unfortunately, many simulations performed today still do not accurately account for flow in such devices.Recently, a significant amount of research into the flow resulting from the metal delivery systems has been performed [5-8]. The thrust of this research has been characterizing the flow patterns by a measurement technique called particle imaging velocimetry. The data suggest that the method of delivering the liquid metal into the mold region has a significant effect on the nature of the flow. With a detailed set of quantitative data from a water model, a numerical model can be built and tested to ensure a proper description of the flow field. The computational model used in these simulations is designed to represent a laboratory scale model of a caster in which ""combo"" bags were simulated. Such bags are mostly of a densely woven glass fiber material with low permeability to aluminum. ""Windows"", of a more open weave, permit aluminum to flow from the bag, see Fig. I. Two different sized combo bags were modeled, each subject to two different outflow window configurations. Furthermore, experimental measurements [9] were used to validate the model results."

Jan 1, 1999