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By Lucio Fabio Cassiano Nascimento, Luis Henrique Leme Louro, Sérgio Neves Monteiro, Jheison Lopes dos Santos, Fernanda Santos da Luz, Fábio Oliveira Braga, Rubens Lincoln Santana Blazutti Marçal, Hugo Concolato de Oliveira Freitas, Édio Pereira Lima Júnior

Epoxy matrix composites reinforced with up to 10, 20 and 30 vol% of continuous and aligned natural mallow fibers and 30 vol% of mallow and jute hybrid fabric were for the first time ballistic tested as personal armor against class III 7.62 mm FMJ ammunition. The ballistic efficiency of these composites was assessed by measuring the dissipated energy and residual velocity after the bullet perforation. The results were compared with that in similar tests of aramid fabric (Kevlar™) commonly used in vests for personal protections. Visual inspection and scanning electron microscopy analysis of impact-fractured samples revealed failure mechanisms associated with fiber pullout, rupture and layers delamination. When compared to Kevlar™, the mallow fiber and hybrid fabric composite displayed practically the same ballistic efficiency. However, there is a reduction in both weight and cost, which makes both, mallow fiber and hybrid fabric composites, a promising material for personal ballistic protection.

Mar 1, 2018

By Aline Maria dos Santos Teixeira

Serpentinite is an ultra basic and metamorphic rock consisting mainly of magnesium, calcium and silicon oxides. The rock under study is a host rock of chromite mine located in Andorinha, BA. The objective of this paper is to evaluate the rock's physical and chemical characteristics to be used as an additional fertilizer of acid soils. After comminution, rock samples were submitted to chemical analysis, XRD, SEM-EDS and TGA. Afterwards, particle size distribution was determined. Result analysis confirms that our rock consists mainly of dolomite, calcite and diopside. According to the result obtained, it can be said that the serpentinite rock has promising applications in agriculture for the correction and additional fertilization of acid soils. However, it is necessary to study the characteristics of the rock such as its dangers and toxicity as well as evaluate them according to the legislation for corrective acidity.

Jan 1, 2010

By Guomin Jiang

Potassium ferrate is an excellent multifunctional reagent for wastewater treatment, but its preparation is crucial. The improved hypochlorite oxidation method was used to prepare potassium ferrate in this study. Iron nitrate, the preferred iron source, was added into hypochlorite solution and then the stabilization agent was added during the purification process of product. The influence of available chlorine content, iron molecular proportion, reaction temperature and reaction time on potassium ferrate preparation was investigated. The optimal condition for potassium ferrate preparation is 15% of available chlorine content , 0.6 of iron molecular proportion , 30i of reaction temperature , 45min of reaction time. The yield of potassium ferrate is about 67% with high purity (> 99%). The structure and performances of the product was characterized by XRD, EDX, SEM, TG and IR and the results show that the prepared product is consistent with the properties of potassium ferrate(VI).

Jan 1, 2010

By Alexandre Bonan

The paper reports on the results of a kinetic study on the oxidation reaction of aqueous free cyanide ions with H202, in the presence of Cu(2+) catalyst. The variables and respective ranges studied were the following: (CN) ° = 10 -100 mg/l pH = 10 -11 (H202/CN) mol ratio = 1 -3 (Cu/CN) mol ratio = 0 -0.25 The results lead to the development of a semi-empirical model whish incorporates both the useful oxidation reaction and the parallel alkaline decomposition of H202.

Jan 1, 1992

By N. El-Kaddah, A. D. Patel, T. T. Natarajan

The phenomenon of particle migration in a conducting fluid under an applied electromagnetic force field finds its application in selective sorting of minerals and more recently in the removal of inclusion from molten metal. This paper deals with the analysis of the expulsion force and the flow around a spherical particle in crossed uniform electric and magnetic fields in .infinite and in confined medium. Analytical solutions will be presented for the electrk and magnetic fields as well as the induced flow at the limit of zero Hartmann number. The flow around the particle was investigated numerically at low and high values of Hartmann number. It will be shown the magnetic field has almost no effect on the velocity field when Hartmann number is less than 1.0. At higher Hartmann numbers the damping effect of the magnetic field was pronounced in the direction of the applied current. It is concluded that Hartmann number has little effect on the net force on the sphere particle.

Jan 1, 1999

By H. K. Lin

Thermodynamics of Cu-C1-H2O system and the kinetics of copper dissolution in cupric chloride solution were studied with emphasis on possible difficulties which may occur during copper electrowinning. E,-pC1 diagram of this system wasestablished. Equilibriumdistributionof various copper chloride complexes of different valent states at the presence of metallic copper was computed through the relations of the simultaneous equilibria. The mechanism-of copper dissolution in the cupric chloride solutions was proposed and the mechanism of copper electroposition was discussed. The researched results were used for guiding the investigation of copper electrowinning from cupric chloride solution.

Jan 1, 1991

By Hideki Minoura

"Two novel electrochemical techniques for the preparation of highly crystallized CdS film have been presented. One is cathodization of a conductive substrate in an acidic chemical bath containing cadmium salt and thioacetamide, where electroreduction of proton at small current densities induces a growth of highly crystallized CdS thin films, whose growth is not disturbed by the reactions in the solution phase. The other technique is electoreduction of aqueous Cd2+— SCN complex. An advantage of this technique lies in no formation of solid particles in the bulk, of the bath.IntroductionIn recent years much attention has been paid to materials preparation by solution processing because of its advantages in lowering the cost as well as the stress to the environment, as compared to the conventional gas phase techniques which unavoidably require high temperature and/or vacuum. We have been trying to explore novel techniques for preparing functionalized compound semiconductors by aqueous solution process. Semiconductors which we have been mainly focusing on are CdS and ZnO, which are important semiconductors finding applications in various devices. In the present paper, some of the techniques that we have recently established for the preparation of highly crystallized CdS will be presented.Methods of the CdS film processing in solution phase (wet process), which have been reported so far can be divided into two major groups; one is chemical bath deposition (CBD) in alkaline solution containing Cd2+ and thiourea 1)4) and the other is electrodeposition (ED) in acidic solution containing Cd2+ and thiosulfate ions - 5)-8) or organic solutions containing dissolved sulfur 9)-11)."

Jan 1, 2000

By Guy Deschênes

In spite of the wide use of lead compounds to enhance cyanidation of free milling sulphide-bearing gold ores, an industrial control method was only implemented four years ago. This study presents the results of the investigation that led to the development of the on-line control technology. Two free milling sulphide-bearing gold ores and high purity minerals were used to develop and test the concept. The first ore contains 2.8 g/t Au, 6.2% pyrrhotite, 2.1% pyrite 0.6 % arsenopyrite, 0.1% chalcopyrite and 0.1% organic carbon. The second ore contains 10.4 g/t Au, 3.2% pyrite, 0.8% pyrrhotite and 0.38% chalcopyrite. The first ore showed a much higher oxidation rate in the pre-leach than the second one and consumed seven times more cyanide. A relation between the formation of thiosulphate and thiocyanate and the additions of lead nitrate were quantified. The ?reducing power?, a titration with permanganate, predominantly determines the concentration of thiosulphate and thiocyanate in cyanide solution. The relation between the reducing power and the addition of lead nitrate at various concentrations of pyrrhotite and chalcopyrite in the ores was established, providing a monitor/control strategy for lead nitrate addition.

Jan 1, 2006

By Ennio Bonetti

The technological applications of MgH2 hydrides for hydrogen storage demand the overcoming of some critical issues: an improvement of the reaction kinetics and a reduction of the desorption temperature. The synthesis of nanocrystalline MgH2 by reactive milling and inert gas condensation and a proper metal catalyst addition, constitute recently employed strategies. In the investigation of the hydrogen short and long-range dynamics, sorption kinetics and nanostructure stability, the mechanical spectroscopy offers some specific advantages. In the present research this technique was employed with other experimental approaches (XRD DSC) to investigate relaxational and structural damping processes in nanocrystalline MgH2 with added catalysts (Fe). Time/temperature variation of the dynamic elasticity moduli and mechanical quality factor are correlated to hydrogen anelastic relaxation processes and concomitant structural transformation of MgH2 to Mg associated to long range H diffusion. Results are discussed with reference to microstructural modification strategies able to assist hydrogen release.

Jan 1, 2006

By Nagahiro Saito, Takahiro Ishizaki, Mituhito Hirota, Akio Fuwa

"Owing to their extremely high toxicity in the environment, the dioxins have been attracting social, technical and scientific attention in recent years. The authors theoretically had predicted the thermodynamic properties of all the dioxins via quantum chemistry and statistical thermodynamics and elucidated the generation-decomposition behavior of dioxins in the equilibrium calculation· of C-H-0-Cl system. In actual combustion processes, it is said that metallic compounds have much influences on the dioxins behavior. The aim of this study is to reveal the roles of metallic compounds the generation-decomposition behavior of dioxins is revealed from the viewpoints of quantum chemistry. Especially, the catalytic effect of copper has been investigated for the reaction, 2HCl(g)--H2(g}+Cl2(g) and for the etherification reaction from precursors, which is Phenol(g) here, to dioxins. The catalytic role of Cu is shown to have much influence on the generation -decomposition of dioxins.1. IntroductionIt is well known that dioxins are very harmful not only for our health but also for that of our children and grandchildren because they are very stable substance and their reaction rates of decomposition are considerably low. On the other hands, it is not well know how dioxins are generated and decomposed; the generation-decomposition conditions and paths as well as the catalysts to decompose them'1l. The authors believe that the thermodynamic and kinetic study of dioxins is useful to find a solution to these issuers. The authors have been investigating the following problems to reveal the generation-decomposition behavior of dioxins; (a) the prediction of the thermodynamic parameters of dioxins (2), (3), (b) the generation -decomposition behavior of non-chlorinated dioxins by the thermodynamic equilibrium calculations in C-H-O system(4) and (c) the generation-decomposition behavior of dioxins by the thermodynamic equilibrium calculations in C-H-O-CI system(5). Summaries of these thermodynamic researches are as follows.(I) The thermodynamic parameters for dioxins, which had been unknown and/or inaccurate'6 l, could be predicted and are available within the scientific accuracy."

Jan 1, 2000

By James O'Brien, Lyman Frost, Grant Hawkes, S. Elangovan, Manohar Sohal, J. S. Herring, Joseph Hartvigsen, Carl Stoots

"Pressing environmental and energy security concerns have brought much needed attention to economic production of hydrogen as the secondary energy carrier for non-electrical markets as well as to meet increasing demand for crude upgrading and desulfurization. While steam reforming of natural gas is currently the dominant method of hydrogen production, it is depleting a valuable fossil fuel while emitting green house gases. Thus, in the long run, efficient, environmentally friendly, and economic means of hydrogen production using nuclear and renewable energy needs to be developed. High temperature electrolysis using solid oxide electrolyte cells is an exceptionally efficient means of generation of high purity hydrogen. It is also capable of directly converting steam and CO2 into synthesis gas. This co-electrolysis process enables conversion of CO2 recovered from concentrated industrial sources into a feedstock for synthetic fuels production. Use of CO2 provides a means of storing hydrogen in a concentrated and convenient form – a hydrocarbon. This is also an effective storage medium for intermittent renewable energy sources such as wind and solar.Ceramatec, Inc and the Idaho National Laboratory are applying solid oxide fuel cell technology to the production of synthesis gas by high temperature co-electrolysis of steam and carbon dioxide. This technology utilizes solid oxide fuel cell stacks to electrochemically remove oxygen from steam and CO2, leaving a clean stream of hydrogen and carbon monoxide suitable for fuel synthesis. By varying the relative concentrations of carbon dioxide and steam, the hydrogen to carbon monoxide product ratio can be controlled as required by the desired type of synthetic fuel being produced from the syngas. The resultant synthesis gas has been used as the feedstock to produce synthetic methane and Fischer Tropsch liquid fuels.Alkaline and proton exchange membrane electrolysis cells typically operate below 100°C, while solid oxide electrolysis cells operates in the 750-850°C range. This higher temperature improves the efficiency significantly. Practically, it translates into a lower cell operating voltage, 1.1-1.4V for high temperature electrolysis vs. ~1.8V for water electrolysis. Hydrogen production is stoichiometric with current in all types of electrolyzers.Carbon dioxide is a valuable resource as a feedstock for energy storage as a hydrocarbon. There is a vast amount of renewable energy that cannot be effectively utilized as grid electricity, but which could be used to convert CO2 to hydrocarbons, offering a solution to the even more difficult (than supplying grid power) challenge of production of sustainable, domestic transportation fuels. Conventional electrolysis and chemical processes could be deployed to accomplish this conversion. However, high temperature co-electrolysis of CO2 and steam to produce synthesis gas using solid oxide fuel cell technology has the potential of improving the efficiency by nearly 50%. A domestic synfuel industry will enable a much larger reliance on intermittent renewable energy than can be accommodated by conventional electric demand profiles while increasing our energy security."

Jan 1, 2010

By Filipe de Menezes Torres, Augusto Pereira de Sa, Itavahn Alves da Silva, Eliana Ferreira Rodrigues, Carlos Antonio da Silva, Varadarajan Seshadri

Top slag eye opening which happens as a result of gas injection is a function of the gas flow rate in addition to other factors such as ladle geometry, porous plug location as well as slag properties. Slag eye opening leads to entrapment of atmospheric nitrogen, oxygen by the steel melt affecting adversely the steel quality. In this work aspects of mixing and eye formation in steel making ladles with inert gas injection have been analyzed through physical and mathematical modeling techniques. Influence of ladle, gas flow rate and distribution and slag properties has been assessed. A correlation for estimating eye opening has been developed. Results from PIV measurements and images of eye opening obtained using a camera have been utilized to validate results from CFD simulation.

Jan 1, 2015

By Ravi Vancheeswaran

The consolidation of ceramic fiber reinforced metal matrix composites is a key process step in the synthesis of high performance composite systems. A simulation tool has recently been developed for predicting the evolution of the composites internal state microstructural variables (eg. relative density, fiber microbendinglfracture, and chemical reaction layer thickness at the fiber-matrix interface) during the consolidation processing of spray deposited composite mono-tapes. A Generalized Predictive Control (GPC) scheme is used in conjunction with the simula-tion tool to design near optimal process paths that minimize fiber damage and reaction product thickness while simultaneously maximizing the composites relative density. The microstruc-tural evolution depends nonlinearly on the process conditions and therefore the scheme uses a constantly updated linearization of the model to optimize the input process variable vector. A control simulation is presented to illustrate the performance of the design scheme and to assess the feasibility of its use for the achievement of goal state microstructures at the completion of consolidation cycles.

Jan 1, 1996

By Ibrahim Yusufoglu, Cem Kahruman, Mert Zoraga

In this study, a strontium sulfate mineral (celestite) was converted to strontium oxalate in solutions containing ammonium oxalate as a reactant. The experiments were carried out under isothermal conditions. The effects of stirring speed, ammonium oxalate concentration, particle size and temperature on the conversion rate were investigated. During the conversion process, definite volumes of solutions were taken from the reactor after different reaction times for the determination of sulfate ions using ICPOES. Fractional conversions of strontium sulfate were determined at different times and fractional conversion vs time diagrams were generated. It was found that the conversion of strontium sulfate was increased by increasing the ammonium oxalate concentration and temperature in addition to decreasing the particle size. The effect of stirring speed was negligible on the reaction rate. It was observed that above 328 K, a protective layer of strontium oxalate was formed on the strontium sulfate particles. X-ray Powder Diffraction technique was used for characterization of solid substances.

Jan 1, 2014

By Yushiro Hirai

Saganoseki smelter & refinery had operated two flash smelting furnaces from 1973, attaining 330,000 mtpy of copper production in 1989. In 1996, however, it carried out a "integration of two flash furnaces". That is, it doubled the feeding capacity to one flash furnace to shut down another furnace while maintaining the same production. Single flash furnace operation has successfully started in March 1996 accomplishing a great reduction of the total production cost. The production had reached to 350,000 mtpy in 1997, and further increased to 450,000 mtpy by executing the expansion program with single flash furnace in 1998. This paper introduces results of the single flash furnace operation and describes about an outline of the expansion.

Jan 1, 1999

By S. Suzuki, Y. Maeda, N. Wakamatsu

"A new pyrometallugical technology, named KLS process, has been developed by Dowa Mining at its Kosaka Smelter to smelt various kinds of lead raw materials.The process consists of clearly separated two reaction steps, smelting and reduction. For this purpose, respective stationary furnaces are installed which are connected by a slag launder.Dry raw materials, together with pulverized coal and oxygen-enriched air, are injected through a lance pipe into the molten slag in the first furnace. It is kept under a high oxygen potential to remove sulfur completely. Resultant PbO rich slag overflows to the second furnace where pulverized coal and insufficient air are also injected through a lance pipe to reduce PbO to lead bullion and to compensate for thermal deficit. The entire operation is carried out continuously. The process development started back in 1981. In late 1986, a pilot plant with a capacity of 3.5t/H was constructed.Already nearly 20,000 tons of raw materials, mostly lead sulfate mixtures have been smelted successfully.IntroductionFor a long time, main raw materials for lead smelting at Kosaka smelter have been such secondary incombustibles as lead sulfate and lead-barium sulfate. The former is leach residue of the copper smelter flue dust and the latter originates from Iijima zinc refinery. While the most of lead concentrates produced locally has been smelted by an ISF of Hachinohe smelter in which Dowa Mining has a share.The surplus lead concentrates were processed at Kosaka by a hydrometallurgical method to convert PbS to PbSO 4 as pretreatment, and followed by simultaneous smelting together with the above secondary materials (1). Approximate output has been 1,5000 /M of lead bullion and slightly more than 2,000t/M of refined lead by adding lead bullion returned back from Hachinohe smelter (2)."

Jan 1, 1988

By Michael J. Marinigh

"Increased safety requirements, higher operational costs, greater environmental restrictions, and new competitive processing techniques are the challenges smelter operators must confront in order to remain economically viable.In converting furnaces which have tuyères such as the Noranda Reactor and the Teniente, Peirce- Smith and Hoboken converters, efficient tuyère line management is critical to optimizing blowing rates, increasing refractory life, and improving safety.This paper will describe recent improvements made to equipment used for tuyère punching, tuyère silencing, tuyère pyrometry and refractory drilling of tuyères and how the proper application of the equipment can lead to operational and safety improvements."

Jan 1, 2009

By Toshiyuki Nohira, Eiichi Takeuchi, Tetsuo Oishi, Hideki Ono, Hirokazu Konishi

The Dy-Nd-Pr-Ni alloy sample was prepared by cathodic potentiostatic electrolysis at 0.65 V (vs. Li+/Li) for 1 h using a Ni plate in a molten LiCl-KCl-DyCl3-NdCl3-PrCl3 system at 723 K. The highest mass ratio (Dy/Nd+Pr) in the alloy sample was observed to be 50 at 0.65 V. Anodic potentiostatic electrolysis at 2.20 V for 12 h was conducted using the Nd-Fe-B magnet electrode in a molten LiCl-KCl system. All elements were almost dissolved from the magnet, and the original form of the magnet disintegrated. After anodic potentiostatic electrolysis at 2.20 V, cathodic potentiostatic electrolysis was conducted at 1.00 V for 5 h using a Mo plate in order to remove the dissolved Fe from the bath. Finally, cathodic potentiostatic electrolysis was conducted at 0.65 V for 12 h using a Ni plate. The mass ratio of Dy/Nd in the alloy sample was determined to be about 18.

Jan 1, 2015

By Kirsi M. Riihilahti

The oxidation characteristics of solid copper matte particles under simulated Kennecott-Outokumpu Flash Converting conditions are presented. The effects of feed matte grade, matte particle size, oxygen-to-matte mass ratio, oxygen content of the process gas and temperature on the particle oxidation rate, quality of conversion, particle size change and particle morphology were determined. The converting quality was highest (~68) with the 58% copper matte at 1100°C. At similar conditions, the 72% copper matte was more likely to produce copper oxides and leave unoxidized particles rather than directly produce sulfur dioxide at 1100°C, resulting in an average converting quality of 55. The quality of conversion was poorest for the 72% matte at 920°C (~45); the sulfur removal was extremely low even with a relatively high degree of oxidation. Fragmentation of the particles was significant in all cases with the 72% matte. A higher O2/matte .ratio and higher temperature, in general, resulted in increased fragmentation while oxygen enrichment had no significant effect. With the 58% matte, particle size was found to increase for the finest fractions rather than to decrease due to particle expansion.

Jan 1, 1998

By Z. Smieszek, J. Botor, Z. Miczkowski, S. Sobierajski

"From 1978, the direct process for the smelting of chalcocite concentrates in a flash furnace by the Outokumpu method has been applied at the Glogów II copper smelter. The chemical composition of these concentrates make it necessary to control the process very strictly. In this paper, the method for controlling and measuring the main technological parameters of the copper production by flash smelting is being presented. It includes the determination of the chemical composition of the concentrate, its grain structure, the temperature of liquid products of the process, oxygen content in process gases, as well as lead concentration in copper and copper concentration in slag.The main process parameters are determined from the mass and energy balances. The relations between parameters, such as an effect of grain structure of a concentrate on oxygen and oil consumption, and dependence of chemical composition of a concentrate on capacity and products quality are discussed. 1. IntroductionThe Polish copper concentrates, as most concentrates occurring worldwide, contain from 18% to 30% Cu, and less sulphur (7-11%) and iron (2-5%). The main copper-bearing mineral contained in the concentrates is chalcocite, while bornite and chalcopyrite are present in smaller quantities. Moreover, the organic carbon (5-7.5%), arsenic (0.05-0.3%) and lead (1.2-3.0%) are also contained in the concentrates. The gangue consists mainly of silica, aluminosilicates, calcium carbonate and magnesium carbonate. Their proportions make the addition of slag-forming agents unnecessary.The composition of Polish concentrates, especially their low iron content, allows their application in the direct flash smelting process for blister copper production. Low sulphur content is the factor which determines the necessity of oxygen application in this process."

Jan 1, 1989