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By Roderick Guthrie

Gas injection into liquid steel baths is widely practiced, ever since the early days of Bessemer’s pneumatic steelmaking process. What has not been fully appreciated is the critical role of bubble sizes for delivering higher quality commercial steels than is presently possible. This was first proposed by Prof P. Hayes and his research group. Using a full-scale water model of a typical 4-strand Ladle-Tundish-Mold system, we demonstrate the potential advantages of modifying a typical ladle shroud, to generate microbubbles within the water flowing into the tundish. This is possible by taking advantage of high shear rates and turbulence kinetic energy available in that region. These microbubbles enhanced the removal of “micro-inclusions” (hollow glass microspheres) in the 5–50 micron size range, to the upper surface of the tundish. There, they were absorbed into an overlaying “slag” phase. Accompanying CFD studies confirmed that no microbubbles in the size range generated (500–900 μm), pass through the submerged entry nozzles into the moulds.

By Joo Hyun Park, Kyu Yeol Ko

The viscosity of the CaO-SiO2-xMnO-yCaF2 slags (C/S=1.0; x=10, 40%; y=0 to 15%) was measured to clarify the effect of CaF2 on the viscous flow of molten slags at high temperatures. Furthermore, the Raman spectra of the quenched glass samples were quantitatively analyzed to investigate the structural role of CaF2 in a depolymerization of silicate networks. The critical temperature of the slags abruptly increased at 15%CaF2, which was confirmed to originate from a crystallization of cuspidine using XRD analysis. The viscosity of the slags continuously decreased by CaF2 addition in the 10%MnO system, whereas the viscosity of the 40%MnO system was not significantly affected by CaF2 addition. The effect of CaF2 on the viscosity of the slags was quantitatively analyzed using micro-Raman spectra of quenched glass samples accompanying with a concept of silicate polymerization index, Q3/Q2 ratio. A polymerization index continuously decreased with increasing content of CaF2 in the 10%MnO system, whereas it was not affected by CaF2 in the 40%MnO system. Consequently, the bulk thermophysical property of the CaO-SiO2-MnO-CaF2 slags was quantitatively correlated to the structural information.

Jan 1, 2014

By Aline Maria dos Santos Teixeira, Francisco Manoel dos Santos Garrido, Joao Alves Sampaio, Marta Eloisa Medeiros

"Rocks for crops is a natural practice for soils fertilization which consists on adding rocks to the soil while water decomposes the rock, through chemical weathering, and gradually releases nutrients to the soil solution. This practice can be considered an alternative to the low production of potassium fertilizers in Brazil. In this context, the phonolite rock was characterized in order to evaluate its application as an alternative source of nutrients to the Brazilian agriculture. The phonolite studied is an igneous, volcanic rock with alkaline character that is chemically composed of a high grade of potassium due to the presence of feldspar minerals. In order to quantify the minerals present in the sample, characterization was carried out using several techniques such as X-ray diffraction, X-ray fluorescence and scanning electron microscopy.IntroductionBrazilian soils are generally acidic and nutrient poor due to the tropical climate in which high temperatures and intense rainfall favor a rapid decomposition of the rocks that from the soil. And as agriculture is one of the main bases of the country's economy, large amounts of fertilizer are used to make the soil productive.Although Brazil has large reserves of potassium, the demand for potash fertilizer is higher than the national supply, which makes the country dependent on fertilizer imports, especially in the form of potassium chloride. Thus, we must look for economic alternatives to traditional fertilizer [1].Stonemeal is a natural practice for soil fertilization that consists in adding basic or ultrabasic rocks to the soil so that water, through chemical weathering, decomposes the rock while it gradually releases nutrients."

Jan 1, 2011

By M. P. Bohrer

A closed-loop hydrometallurgical process has been developed for treatment of smelter flue dust generated by copper recycling. The process is a semi-continuous operation in which zinc, iron, and copper are first extracted from the dust with a sulfuric acid solution. The lead and precious metals, initially present in the dust, remain as solids and can be recycled to the copper smelting furnace. Cementation with iron and zinc metal purifies the zinc and iron-rich liquid stream prior to spray drying. The spray-dried product, consisting of a mixture of zinc sulfate monohydrate and iron sulfate monohydrate, is a desirable micronutrient additive for use in animal feeds. Treatment of the smelter flue dust in this manner will generate a positive return on investment, as well as mitigate a potential environmental liability.

Jan 1, 1992

By R. Harris

Blister copper melts of 800 g to 1000 g containing less than 1 wt % S and up to 3 wt % Ni were desulfurized at 1523 K in air or by a pure oxygen jet blown at 75,500 and 1000 cm3/min, from 1 cm above the melt. Rates of desulfurization and oxygen pickup were measured and visible surface phenomena were photographed and videotaped. It was observed that SO2 was evolved from Cu-S melts in a manner reminiscent of the effervescence seen in carbonated drinks. The effervescence lasted up to 20 minutes and resulted in the ejection of material up to a height 50 cm above the melt surface. Sporadic discharge of large bubbles was also observed in a Ni containing melt top-blown with oxygen at 1000 cm3/min. The Cu-S melts top-blown with oxygen experienced faster sulfur elimination as compared to stagnant melts exposed to air and experienced only a single period of turbulent SO2 evolution, which occurred almost immediately after oxygen injection commenced. The Cu-S melts exposed to air experienced multiple episodes of effervescence. The stagnant blister copper melt containing nickel did not exhibit effervescent behaviour and experienced a lower rate of sulfur elimination compared to Cu-S melts tested under similar conditions. The present article examines the role of surface phenomena in determining the observed behaviour.

Jan 1, 1999

By Mikiya Tanaka, Mikio Kobayashi, Kazuya Koyama, Yoshihiro Nishisu

Preparation of multicomponent powders are very useful and important for producing the materials with complicated and homogeneous structure. Therefore multicomponent powders have a lot of attention in the field of advanced value-added materials. The aqueous processing in hydrometallurgy has a broad potential for producing multicomponent homogeneous precipitates. Furthermore the aqueous processing has a future potential for integrating the separation, precipitation and synthesis processes. In this presentation the precipitation from homogeneous solution including rare-earths and/or common metals is presented. These precipitates probably consist of almost monodispersed, multicomponent and spherical particles by precisely controlling several reaction factors, reaction temperature, concentrations of starting materials, pH and so on. The separation of the nucleation stage and the growth stage of the particles is very important and how to control the reaction factors to realize enough separation is discussed. In this presentation the systems of Y-Eu-0, Y-Fe-0 and Y-Al-0 are mainly presented. In addition the precipitation-stripping method from organic phase is presented focusing the synthesis of multicomponent powders of Ni-La-0 system. These precipitates have multicomponents homogeneously and so they are converted to multicomponent ceramic powders by calcination. They are important compounds as phosphor, opto-magnetic materials, optical materials, hydrogen storage alloy or as the related precursors. In this presentation some characterization of these particulate materials is included.

Jan 1, 1998

By M Phil Schwarz

"A CFD model for the gas-side of an impinging jet iron bath reactor has been developed to assist in the interpretation and design of oxidizing gas-melt reaction rate experiments. Heat transfer and reaction at the surface have been included. A free surface model, which solves for the liquid motion within the bath as well as the gas motion above the bath, has also been developed. This model also predicts extent and shape of the dimple formed on the liquid surface by the impinging jet. Both models have been run for conditions typical of jet impingement experiments using CO2 , H2O and O2• The main conclusions are• Results from the model for gas-side mass transport are in good agreement with the empirical correlation of Belton and Belton (1980)• Experimentally determined rates of decarburization by CO2 should be corrected for mass transfer because the experiments are often carried out under mixed rate control, eg for gas flow rate 10 L/min when the sulphur concentration is lower than 0.045• If the rate constant for oxygen reaction is greater than about 5 mol/m2.s.atm, it cannot be determined using a gas flow rate of 10 L/min or lower because of mass transfer control.• A cavity of depth 4.5 mm is predicted for a gas flow rate of 10 L/min and this substantially changes the flow field (and hence reaction rate) compared with a simulation in which the surface is assumed to be flat."

Jan 1, 1999

By K. Suseelan Nair

Magnesium alloys containing rare earths are finding increasing applications in space programmes. A number of alloys have been developed and e good data base an the mechanical properties of these alloys is available. However details on metallurgical aspects are found to be sparse in, literature. This paper, at first, briefly reviews the available data on these alloys and subsequently presents the microstructural investigations conducted on quatenary fig-4.9% Zn-1% Rare earth-0.5% Zr cast alley, using optical metallic-graphy, electron probe micro-analysis and X-ray diffraction techniques.

Jan 1, 1989

By Yamei Han, Jiang Du, Jinhui Peng, Mengbi Fu, Libo Zhang, Zhengfu Zhang

"A continuously pilot synthesis by microwave-heating was used in preparing the cathode material LiNi113Co113Mn11302 for Li-ion battery, which used Ni1/3Co1/3Mn1/3(0H)2 and LizC03 as raw materials. Decomposition of the raw materials and synthesis of LixNi113Co113Mn11302 would be fmished in single roasting process. In addition, using microwave-heating would reduce the reacting time largely. Furthermore, the yield of LixNi1/3Co1/3Mn1/302 synthetized in single roasting process was 50 kg. Meanwhile, the effects of Li:(Ni+Co+Mn) molar radio (Li:(Ni+Co+Mn)=l.06, 1.075, 1.09, 1.15) was studied in this paper. XRD, SEM and EIS were used in characterizing the cathode material. The results showed that the best Li:(Ni+Co+Mn) molar radio was 1.075. It was found that the LiNi113Co113Mn11302 synthetized with Li:(Ni+Co+Mn)=l.075 had homogenous distribution of particles and ideal layered structure. The galvanostatic charge-discharge(O. l C, 2. 75-4.3V, vs. Lt /Li) tests showed that the initial discharge capacity of the LixNi113Co113Mn11302 was 159.5mAh·g-1, and the discharge capacity was 157.6mAh·g·1after10 cycles.IntroductionRecently, as the cobalt was expensive and the restriction of dynamic power, the commercial cathode Li2Co02 which was expensive, toxic, and high pollution had exposed its defects[1·2l. Since T.Ohzuku[3l first reported the layered LiNi113Co113Mn11302, this material had high reversible capacity and caused the attentions of researchers[4l. Its reversible capacity was l 60mAh/g and 200mAh/g in the voltage range of 2.75-4.3V[5-61. But for the present, preparing LiNiwCowMnw02 by traditional had lots of disadvantages, such as the long heating time, the high cost and the volatizing of lithium and so on[7-9l. According to these, traditional prepatation wasn't good for sustainable development and energy conservation."

Jan 1, 2013

By S. -H. Jeon, Y. -S. Choi

"The three dimensional current distribution on the rectangular cathode is predicted using a boundary element method with a linear element of trigonal type. The effect of cell geometry and anode shape on current distribution is simulated. Calculated results compare well with experimental results. The proper combination of anode size and distance between electrodes increase the current uniformity.The importance of electrodeposition as a fabrication technology in the electronics industry is large and growing. The main advantages of this wet processing method, in comparison to other dry processing methods, lie in its high yield, rapid processing and low cost. In nearly every application of electrodeposition the pursuit of deposit uniformity, especially thickness uniformity, has been technically imperative. The thickness uniformity of the deposit depends largely on the current distribution over the cathode. The current distribution is primarily determined by the geometrical characteristics of the electrodes and the cell. Also the polarization at the electrode surface and the mass transfer affect the current distribution.The current distribution is an important consideration for those involved in designing electrochemical systems and electroplating systems in particular. Although it is important, the common practice in industry is to use trial and error method to design the cell that optimize the uniformity of current distributions in electroplating. The purpose of this paper is to illustrate the useof boundary element method to predict three-dimensional current distribution in rectangular cell.The calculation of the current distribution is possible by various numerical techniques, which include the finite difference method (FDM)1, the finite element method (FEM)2, and the boundary element method (BEM)3,4. These methods of the numerical calculation have various problems, respectively, but the BEM is considered to be the most efficient. This is due to the fact that the BEM has the advantage of solving field equations only on the surface of a calculation domain. A good comparison between the BEM and the FEM for the secondary current distribution in a Hull cell was made by Matlosz et al.5The fundamentals on the theory of current distribution in electroplating are well-established in the literature by a number of authors.6, 7, 8 However, a small fraction of these works have been specially addressed to three-dimensional analysis, and, mostly thel·10 have focused on the problem qualitatively rather than quantitatively.Extending the previous work to three-dimension, we developed the program for the quantitative calculation of 3-dimensional current distribution using a boundary element method with a linear element of trigonal type. Integrals with singularity from the fundamental solution have been analytically computed and it is shown in detail in the Iiterature11. This paper deals with the three dimensional current distribution for the electrode position of copper in a cubic type cell and the effect of anode shape, size and the distance between electrodes on current distribution is studied."

Jan 1, 1997

By T. Watanabe, T. Fujiwara, S-Wan Song, Y. Nakagawa, R. Teranishi, M. Yoshimura

"We have tried a new method to fabricate cobalt oxide films onto porous films directly by an electrodeposition method at low temperature. The porous substrate films (membrane-filters and paper) were placed between a LiOH solution and a CoSO4 solution and treated under electricalcurrents of ~1 mA/cm2 using carbon cathode and anode. Effects of temperatures, flow rates and electrical currents have been investigated. As a result, we found that the LiCoO2 films and Co3O4 films were successfully fabricated on paper and/or porous PTFE filters at 120 °C, while CoOOH films were deposited at 80 °C. Furthermore, LiCoO2 films did not cover whole the substrates, but was fabricated just over the anode. The chemical reactions of electrodeposition were also considered from these results.IntroductionRecent agreements on global environment require rapid progress of low energy and low waste processings for the fabrication of thin films that succeed to the mass production with the high consumption of the fossil fuels (such as physical vapor deposition°, chemical vapor deposition2), dip coating with firing3) etc.). The total energy consumption in aqueous systems should be the lowest among all these processing routes, because a much lager excess of energy is necessary to create melts, vapor, gas, or plasma than to form an aqueous solution at the same temperature4)The ""Soft Solution-Process"" (SSP) was one of the best concepts to realize the low energy and low waste fabrication of inorganic materials. 5) Generally speaking, SSP gives similar results to any other processing using fluids (such as vapor, gas plasma) and/or beam/vacuum processing. However, the total energy consumption of all these possessing routes should be the lowest in aqueous systems, because a much larger excess of energy is necessary to create melts, vapor, gas or plasma than to form an aqueous solution at the same temperature (Fig. 1). This idea can be easily demonstrated, using the simple example of BaTiO3. The energy diagram for the formation of BaTiO3 from various precursors is shown in reference 4. The driving forces (AG) for representative synthesis reaction of (1), (2), (3), (4) and(5) are 38, 727, 3685, 17 and —14kcal/mol, respectively at room temperature. 6' 7"

Jan 1, 2000

By Lauri Holappa

Copper converting is mostly performed in Peirce-Smith converters. The process is still very similar to the original one developed in the early 20th century. It is a batch process in a horizontal cylindrical reactor with air blowing via tuyeres along the length of the reactor side. The Peirce-Smith converter has its roots in Bessemer's inventions in the 1850's as he tested both horizontal and vertical vessels for steel converting. However, for steel making a vertical pear-shaped converter with air bottom-blowing was established. In the course of time, there was a distinct necessity for oxygen usage instead of air due to harmful effects of nitrogen to steel properties and its cooling effect. In-bath blowing of oxygen did not succeed, however, and top-blown oxygen converter with oxygen lance (LD or BOF) was first developed in he 1950's and emerged rapidly to a dominating position. Somewhat later oxygen bottom-blowing via special shrouded tuyeres was developed (OBM or Q-BOP) but has attained only fractional share. Bottom-blowing technique had, however, impact on the current combined blown converters which adopted the benefits of both top and bottom blowing. In copper converting Peirce-Smith type converters have kept their position until today although new processes have been introduced and at least few of them seem to be emerging. In one respect copper converting has a clear leading position i.e. in the progress of continuous converting processes (Mitsubishi, Ausmelt). These processes utilise top-blowing lances instead of in-bath blowing tuyeres. A different principle for continuous converting is flash converting by Kennecott Outokumpu, which makes smelting and converting independent of each others. Solid ground matte is used as a feed for flash converting in a reactor shaft similar to Outokumpu matte flash smelting. A comparable process has been presented by Inco too. The paper discusses principal physico-chemical and process technical similarities and differences in copper and steel converting. Although these processes are metallurgically quite different it seems that during the modem history of ferrous and non-ferrous metallurgy, starting from the 1850's, the exchange of knowledge between these disciplines has been quite intensive. In long-term perspective, many similarities in the development can be found but also divergences due to different ambient circumstances.

Jan 1, 2003

By G. Archer

ASARCO, a large and diverse producer of nonferrous metals, is involved primarily in the smelting and refining of lead and copper. Lead-antimony alloys, antimony trioxide, bismuth, cadmium oxide, selenium, tellurium, silver and gold are among products which result from processing by-products of smelting and refining. The complex mixture of concentrates at some smelters and the high impurity loads at some refineries result in various drosses, sludges, dusts and slags. In this paper, the complex interplant and intraplant transfer of by-products is addressed. These by-products result in an exchange of metals between the lead circuit and the copper circuit. Examples of the transfer of by-products and the prospects for the recycle of valuable products from wastes generated by customers and unrelated processors are also discussed.

Jan 1, 1992

By W. Riekehof

The paper explains required practice and equipment for capturing airborne fumes and particulates in hot-dip zinc galvanizing plants. An economic and technical comparison of enclosure and tank rim suction options is presented. The paper also compares the performance of various filter media in filtering fumes, to determine the effect of changes in flux as well as changes in filter finishlcoating methods. This includes a recommendation for how to achieve the best result with respect to pressure loss and cleaning behavior of the filter.

Jan 1, 1992

By Mitsuru Tanahashi

In order to develop an effective process for the production of a solar-grade silicon (SOG-Si) from metallurgical-grade one (MG-Si), the oxidation removal of boron from molten MG-Si was investigated at 1773 K by the following two CaO-saturated CaO-CaF2 flux treatment processes. I) Boron removal by flux addition onto the molten MG-Si followed by oxygen gas injection into the melt (Two-stage connecting process). II) II) Boron removal by simultaneous injection of flux powders and oxygen gas into the molten MG-Si (Simultaneous injection process). These processes can establish the special condition of both high basicity of the flux and the high oxygen partial pressure at the boron removal reaction sites. Through these processes, especially by the simultaneous injection process using a flux powder injection equipment, the boron content in MG-Si can be efficiently reduced. The obtained results clarified that both processes should be conducted for a time period as short as possible by using as much flux as possible. By repeating the simultaneous injection process for 60 s three times under the optimum operating conditions determined in the present study, the boron content in MG-Si can be reduced from 14 to 4.7 mass ppm.

Jan 1, 2003

By Fernando Castro

Electric furnace steelmaking dust is a polluting residue that needs to be treated in order to recover metals contained and to produce an environmentally acceptable residue. Some hydrometallurgical approaches for its treatment have been evaluated, namely: caustic soda leaching followed by electrolytic recovery of zinc, ammonia leaching followed by zinc compounds precipitation and acetic acid leaching followed by lead, zinc hydroxide and gypsum precipitation.

Jan 1, 1992

By Bret Boster

Facilities at Amax Gold's Sleeper Mine process some 330 kt of high grade ore and 4100 kt of low grade ore annually to produce 6.8 t of gold and 7.8 t of silver. High grade ore is processed in a conventional milling facility employing gravity concentration, CIC and CIP unit operations for gold and silver recovery. Low grade ore is processed using heap leaching and carbon adsorption methods.. Presented are the evolution and descriptions of the Sleeper processing facilities and discussions of selected' operating results.

Jan 1, 1989

By G. Gerbeth, Y. Gelfgat, A. Cramer, A. Bojarevics

The production of highly porous metallic substrates requires an effective and well controlled production of metallic fibres with diameters in the range of 50 to 200 microns. The melt extraction, where a quickly rotating wheel extracts fibres directly out of the inductively heated melt, is a promising technology for that purpose. The main limitations of this process are due to turbulence within the melt and a wavy motion on the surface. Both effects give rise to strong and time dependent deformation of the melt surface which, in turn, causes non-stationary conditions of the contact zone between the extraction wheel and the melt. In the patent literature many examples can be found which try to overcome these problems by submersing mechanical parts directly into, or placing them at least in close vicinity to the melt, aiming at a stabilisation of that contact region. Even made of heat resistant ceramics they suffer from corrosion or cracks and do not work reliable at all. The present work describes a non invasive control mechanism by means of a magnetic field. Model experiments were carried out to study the calm down of the turbulent surface of a inductively stirred melt. The stabilisation of the melt surface has been demonstrated in practise by the installation of a solenoid at a working extraction facility under rough industrial conditions like a powerful induction heating and vacuum.

Jan 1, 1999

By H. Kamiya, H. Hasegawa, M. Nojiri, S. Matsui, Y. Fukuda, M. Tsukada

"The present paper focuses on the action mechanism of anionic polymer dispersants in dense Si3N4 and SiC suspension. An atomic force microscope (AFM) was used to determine the relationship between the macroscopic suspension viscosity and the microscopic adsorbed structure of a polymer dispersant at the solid / liquid interface. The surface interactions within the suspensions were analyzed in various dispersant pH and additive conditions. The addition of an anionic polymer dispersant decreased Si3N4 and SiC suspension viscosity and increased electro-steric repulsion force on the non-oxide surface in solution at pH> 6 which was the isoelectric point of the materials. It was assumed that the increase of repulsive force was promoted by a hydrophobic adsorption of polymer dispersant on the non-oxide particles.IntroductionThe surface of silicon nitride and silicon carbide powders in a water suspension system has quite a complex molecular structure. In the case of Si3N4, hydroxyl and ammonium groups form on the surface and the pH of the suspension is increased from neutral to about 10 due to surface oxidation. The particle surface is negatively charged in alkaline solutions (pH=10), because the isoelectric point of silicon nitride exists in the pH range from 5 to 6. However, in spite of charging the negative surface charge, an anionic polymeric dispersant is generally used for the reduction in slurry viscosity.In dense SiC suspensions, an anionic polymer dispersant is generally used in order to disperse aggregates and reduce the suspension viscosity, too. Since an anionic dispersant is used in alkaline solutions higher than the isoelectric point of silicon carbide, the dispersant adsorbed on the negative charged surfaces of SiC.Few researchers have discussed and estimated the adsorption mechanism and structure of anionic polymeric dispersants on silicon nitride and silicon carbide surfaces. This is because it is difficult to observe the structure and measure the interaction at the solid/liquid interfuce directly. However, new developments in surface-force measurement technology have enabled the determination of non-DLVO type interaction for analyzing aggregation behavior2. The use of the AFM for analyzing the effects of various surfactants and co-polymers on colloidal dispersions and solid surfaces has also begun to rapidly expand to characterize the interaction between solid surfaces."

Jan 1, 2000

By Daniel Chen, Jewel Andrew Gomes, Venkata Palla, Sadia Afrin Jame, David Cocke, Paul Bemazzani

"Textile industries use various kinds of chemicals including dyestuffs and pigments during dyeing and finishing processes. The effluent from these processes includes suspended particles, strong color, high pH and high chemical oxygen demand (COD) that are extremely toxic and make environmental hazard. Although physical, chemical, photochemical, and biological methods are available for treating such wastewater, the electrochemical technique, electrocoagulation (EC), has emerged as an efficient, simple, and cost-effective technology in the last few decades. In this study we present the applicability of EC technique for removing dye, such as direct red dye using iron electrodes, and the optimized conditions such as dye concentration, current density and pH. The degradation of dye molecules was investigated using UV-visible spectroscopy. The EC-floe was also characterized using SEM/EDS, XRD and FTIR.IntroductionWastewaters generated by textile industries contain large amounts of toxic aromatic compounds, especially azo dyes. Azo dyes and their degradation products, such as aromatic amines, are highly carcinogenic. These effluents are also responsible for causing high levels of color. The colored wastewater released into the environment is also a source for disruption of aquatic life and aesthetic pollution as well [1].In most textile industries, dyeing and finishing are the two important processes which are generally applied. These two common processes generate significant amount of wastewater, which may contain, suspended particles, high pH, strong color and high chemical oxygen demand (COD) concentration [2]. Low pH and high temperature are other polluting factors from the waste water. Textile industries make use of about 10,000 dyes and pigments [3]. Disposal of these colored wastewaters poses a major problem for the industries as well as a threat to the environment. In textile industries, because of the low efficiency (60-90%) of dye fixing on textile fibers, substantial amounts of unfixed dyes are released in waste waters. The conventional method for treatment of textile wastewater was a combination of biological, physical and chemical methods [2]."

Jan 1, 2011