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By Guan-zhou Qiu, Shui-shi Liu, Yu-feng Guo, Tao Jiang

"The preparation of high-quality synthetic ruitle from electric furnace titanium slag was systematically investigated by activation roasting followed by acid leaching process. The results showed that impurities such as Ca and Mg in titanium slag can be effectively removed and TiO2 grade of the product was markedly improved by the process. High-quality synthetic rutile containing 88.54% TiO2, 0.42% (CaO+MgO) was obtained under the conditions that roasted with 7.5%(wt) H3PO4 at 1000 oC for 2h, followed by two-stage leaching in boiling dilute sulfuric acid for 2h. Mechanism studies showed that anosovite solid solution and silicate minerals were reacted with phosphoric acid in the roasting process. As a result, titanium components in titanium slag turned into rutile (TiO2) and impurities were transformed into acid-soluble phosphate and quartz.IntroductionWith the gradual depletion of natural rutile and the rapid development of titanium industry in China, the natural rutile reserves cannot satisfy the requirement for production of titanium pigment and titanium sponge. Ilmenite is, therefore, becoming main raw material for titanium industry. However, because of its low TiO2 grade, it generally requires preconcentration to titanium-rich material such as titanium slag or synthetic rutile [1-3].Ilmenite resources are extremely rich in Pan-xi area of China, which account for 90.54% of total ilmenite reserves in China [4]. The titanium slag produced by electric smelting of ilmenite concentrate has high contents of Ca and Mg, and is not suitable as a raw material for chloride process and titanium sponge production. Therefore, upgrading titanium slag to prepare raw material suitable for chloride process and titanium sponge production has important significance for the development of China's titanium industry."

Jan 1, 2011

By Nozomu Uchida, Uematsu Keizo, Daisuke Shouji

"Grain orientated microstructure was developed for the improvement of ceramic characteristics. Novel polarized light microscopy was developed to examine the grain orientation quantitatively. The degree of grain orientation was estimated from the retardation determined with a Berek compensator. The method was essential to determine a minor grain orientation, which could not be analyzed by means of conventional X-ray measurements. The data were favorably related to ceramics characteristics. The comparis of the ceramics with various degree of orientation was very important to explain the change of ceramic characteristics with processing.IntroductionMicrostructure with grain orientation has a high potential for greatly improving characteristics of ceramic. However, there has been strong restriction on processing and material for developing this structure. It has been crucial to apply forming methods involving high shear such as injection molding1). Grains must have an elongated shape.In recent years, much attention has been paid on the effect of high magnetic field on diamagnetic materials2)3)4), Many ceramic materials are known to be diamagnetic. High magnetic field has a high potential to orient grains. The principal driving force for grain orientation is the magnetic anisotropy of material, which is generated by non-cubic crystal symmetr5). This method of grain orientation is not restricted by grain shape, and can be applied to all materials having non-cubic crystal structure.This study uses alumina as raw materials, and produces alumina ceramics with orientated grain in high magnetic field (10T). Alumina has a magnetic anisotropy due to hexagonal crystal structure. The degree of grain orientation in the green and sintered bodies will be examined and their relevance to magnetic field will be discussed."

Jan 1, 2000

By L. A. Barta

A new process for the leaching of chalcopyrite concentrates has been developed and tested in miniplant campaigns and locked cycle testwork carried out between 1996 and 1999. The process involves pressure leaching in a sulphuric acid solution, e.g. raffinate from copper solvent extraction. Iron in the feeds is precipitated predominantly as hematite in the autoclave, simultaneously with copper extraction. Gold and silver in the pressure leach residue are recoverable by conventional cyanidation, following flotation to remove elemental sulphur by-product. The results of recent miniplant tests and batch locked cycle tests are provided.

Jan 1, 1999

By Xiaojie Gao, Jingshe Li, Chengsong Liu, Haiyan Tang

In order to clarify the reaction between MnO-SiO2 oxides with low FeO content and Fe-Mn-Si alloy, two diffusion couples were produced by the new method using confocal scanning laser microscopy (CSLM). The interface of the alloy and oxide, content of Mn and Si in the alloy near the interface, size distribution and composition of the particles which precipitated in the alloy were observed and analyzed using the electron probe microanalysis (EPMA). Results show that though the FeO content in the oxides decrease to 1% which is lower than the equilibrium with the molten steel at 1873K, the diffusion of oxygen from oxide to alloy still exists during the heat treatment at 1473K and causes shorter Particle Precipitated Zone (PPZ) and Manganese Depleted Zone (MDZ) normally for the reduction of diffusion flux of oxygen.

Jan 1, 2015

By K. Pagalthivarthi, P. V. Desai

"During solidification of alloys, many inter-related physical processes, such as melt convection, mass diffusion, heat transport, macrosegregation and melt-undercooling occur. Several research workers have studied one or more of these effects separately. To answer important questions on solidification behavior, an overall approach interrelating the processes is necessaryAs a first step toward accomplishing the overall modeling, the freezing of a binary liquid metal is examined. The various stages during freezing of the alloy are critically described to build a continuum model for the entire process. Diffusive mixture theory is used to write the conservation equations for the liquid and the mushy zones. The concept of local thermodynamic equilibrium in the presence of curvature effects is used to restrict the number of degrees of freedom within the mushy zone. Constitutive equations relating flux quantities and affinities, the governing differential equations and boundary conditions are discussed briefly for the freezing process.IntroductionA solidification study encompasses such facets as solifidication time, microstructure, macrosegregation of the solute, shrinkage effects and soundness of the casting. Influence of one or more of the coupled heat and mass transfer phenomena such as local solute redistribution, thermosolutal convection, melt undercooling at dendrite tips and heat dissipation to the ambient have all been previously examined [1-3J. Several studies have examined the individual facets of alloy solidification as isolated processses. In fact, the transport processes occur simultaneously and a comprehensive model should include their inter-relationships. In particular, some of the existing studies of the mushy zone [4-6J do not emphasize thermodynamic completeness. This work represents an attempt to develop a thermodynamically consistent model of the entire solidification process on physical grounds."

Jan 1, 1986

By Jorge Alberto Soares Tenório

Household zinc based batteries contain some heavy metals such as zinc, manganese and mercury. There is a large effort from manufacturers in order to eliminate the last one. As a municipal waste, the disposal of batteries has become an increasing worry. The aim of the present work was to characterize dry batteries scraps, and establish a flowsheet for their processing. This was done using unit operations of mineral processing and parameters and yields of each stage have been defined. Such procedures have been chosen due to their low cost. The operations were hammer mill grinding, size separation, magnetic separation and specific weight separation in water. The characterization step was done through chemical analysis and x-ray difiactometry. After size classification, it was verified that 76.6% of the total amount of zinc was over 1.70mm. This fiaction was constituted basically of zinc and some coarse pieces from the steel body, paper and plastics. This fraction was submitted to magnetic separation followed by specific weight separation in water. A visual examination showed that during the grinding process, graphite was concentrated in the finer fractions. Manganese concentration in the fractions over 6,35mm was less than 2%. This means that there was low contamination by the paste in this fraction. It was due to the entrapment of the paste by steel scraps (from the body) and zinc (from the cup) during grinding.

Jan 1, 1999

By D. C. Azubike

Wolframite (FeWO4) usually having cassiterite (SnO2) as a major impurity is a primary source of tungsten. Its direct reduction/carburisation with carbon in the temperature range 1000-1400°C, and with hydrogen at 600-900°C followed by carburisation with CO at 900°C are described. Depending on the conditions and reactants employed, Fe, Fe2W, B-Sn,WC, W2C, Fe3W3C and Fe6W6C are the products. Tin was found to inhibit the overall reduction and carburisation reactions significantly. The potential for either efficient separation of iron and tungsten or a one-stage production of an iron-based metal carbide composite is discussed.

Jan 1, 1992

By Nobuaki Sato

For decontamination of SO2 containing waste gases from industries such as ferrous and non-ferrous metal companies, desulfurization with hydrogen production by the reaction of Br2 and SO2 was proposed as bromine-sulfur (BS) process. In this process, SO2 is fixed as H2SO4 in the presence of Br2 and H2O forming H2SO4 and HBr. Then hydrogen is produced by the decomposition of HBr and Br2 as byproduct is recycled. The reaction of Br2, SO2 and H2O was found not to occur in liquid phase but to occur in vapor one. The production ratios of H2SO4 and HBr showed a maximum at temperatures around 60 oC. The highest production ratio was obtained at 70 oC with a mixing ratio of Br2:SO2:H2O=1:1:10. The experimental results were discussed with thermodynamic consideration.

Jan 1, 2006

By Dhanesh Chandra

In this symposium, research in the area of energy conversion is presented. This symposium has special significance, as we honor three prominent scientists from hydrogen storage research and development field. In this symposium, the majority of papers presented by international scientists and engineers are in the area of hydrogen storage. Other energy conversion papers include magnetic materials, superconductors, and thermal energy storage materials. Recent developments in light-weight high gravimetric hydrogen density hydrides have led to potential use of hydrides for onboard automobile and other applications. This, of course, is significant from environmental concerns of CO2 and other emissions from the current use of carbon based fuels in automobiles. Thus, it is becoming increasingly important to switch to cleaner alternative fuels such as hydrogen [1]. The Challenge of Vehicular Hydrogen Storage as potential hydrogen energy carriers for vehicular applications, with a driving range of approximately 300 miles, require ~5-13 kg of hydrogen stored on-board. In the United States, Centers of Excellence have been established in metal hydrides, chemical hydrides, and carbon-based materials, and abundant scientific and industrial research is being carried on metal hydrides; only some of the current research from the Centers will be reported here. The European commission, Japan Institutions, and others also have numerous hydrogen storage programs in progress. Several international collaborations have also begun between IEA and IPHE scientists to accelerate the progress of development of practical hydrides. A summary of the abstracts is included in this overview.

Jan 1, 2006

By Raj P. Singh

Lewatit TP207, a chelating resin with iminodiacetate functional group, is used for the purification of cobalt hexammine chloride solution for divalent cationic impurities (US Patent No. 5,154,757). The method is employed at commercial scale in OSRAM SYLVANIA Inc. cobalt chemical production since 1992. It is observed that after long use in the purification of cobalt hexammine chloride solution, a large number of resin beads tum black from their original beige color. The purpose of this paper was to characterize these black-colored resin beads for their ion exchange behavior. The resin sample used in this work was an exhausted production TP207 resin containing large number of black-colored beads. The results indicated that blackened resin beads can be regenerated to almost full capacity and' their ion exchange behavior for the purification of cobalt hexammine chloride solution was comparable to the new resin.

Jan 1, 2001

By J. Murphy

The economics of microbial coal desulfurization are affected significantly by the proper selection of the plant site and by maintenance of variables at suitable levels. High sulfur coal particles below 200 mesh show sulfate production rates triple those with 150 mesh coal but grinding costs are greater. Slurry solids density increases from 5% to 20% reduced the rate constant by a factor of 10. Coal added to a batch reactor in the stationary phase resulted in a sudden second exponential sulfate production phase indicating feasibility of lower cost continuous operation. Successful operation in the absence of beef broth, yeast or added nutrients at non-sterile conditions enhanced projected economics. Finally, the need for adequate agitation and aeration was well established.

Jan 1, 1985

By Jing Zhang, Chenguang Bai, Fusheng Pan

"The microstructure and hot deformation behaviour of an Er-modified Mg-Zn-Ai alloy were evaluated. The results showed that the addition of rare-earth Er changed the morphology of the quasi-continuous grain boundary networked eutectic compound to globular particles. Moreover, a self-strengthening effect was identified for the alloy, which determined its deformation behavior. After hot extrusion, the yield strength and elongation to failure of the Mg-Zn-AI-Re alloy at 200°C were increased by 105% and 120%, respectively, due to an emerged dynamic precipitation strengthening mechanism.IntroductionMagnesium alloys are attracting increasing attention for applications in automobile, electronic devices and hand tools for weight reduction and higher fuel efficiency, because of their lightweight and a high specific strength. However, application of Mg is still very limited. The largest applications are still those non load-bearing castings used at room temperature, such as box case, housing, and covering. One of the main reasons is the inadequate absolute strength both at room temperature and elevated temperatures (> 100°C) of the commercially used AZ, AM series alloys, due to the incoherent interface between the secondary phase y-Mg17AI12 and Mg matrix, as well as the low thermal-stability of the y phase [1]. Besides, the heat-resistant magnesium alloys which contain rare earth (Re) as the main alloying element are very expensive. The other reason is their poor deformability. The key solution is therefore to develop low-cost heat -resistant wrought alloys."

Jan 1, 2012

By Donghai Li, Cheng Pan, Xuyang Liu, Xuewei Lv, Chenguang Bai

"Fine chromite ore is the common raw material to produce ferrochrome alloy through the submerged electric furnace process. The electric resistivity of fine chromite ore plays an important role in the operation efficiency because it determines the current distribution. The effect of particle size and the contact area of the particles on electric resistivity for several of chromite were investigated at room temperature, and the relationship between the electric resistivity of mixed particles and the volume fraction of lump ore to fine ore was also studied. The results shown that the electric resistivity increases with the increase of particle size, and the electric resistivity of mixture decreases with the increase of volume ratio of fine ore.IntroductionChromium is one of the most important alloying elements in manufacturing of stainless steel that used at high temperature and corrosive environment applications [I, 2]. As the raw materials to be charged into the steel, ferrochromium alloys and charge chromium are produced directly by smelting of chromite ore with the reducing agent in submerged electric arc furnace (SAF). During the process, the oxides of chromium and iron were reduced by carbon and meanwhile the electrical energy were consumed [3,4]. The ideal industrial process is to achieve high recovery level of Cr and Fe with minimal power consumption. In SAF process, the electric resistivity of charge stock has significant effect on the current distribution, which determines the heat distribution, molten bath structure and chemical reactions in the furnace. High resistance of the charge is desired to reduce the current distribution through the charge stock, thus the electrodes may insert into the charge stock with proper depth to form a high temperature arc heat source, and proper smelting can be realized[5]."

Jan 1, 2012

By J. R. Donald

For processing copper, continuous converting has been successfully employed in a variety of locations, but for nickel, there has yet to be a successful commercial implementation of continuous converting technology. At Inco?s Copper Cliff smelter, there are specific requirements for the production of Bessemer matte relating to downstream processing that makes continuous converting for nickel mattes even more challenging. The nickel carbonyl refineries require very low iron levels in the matte, and the sulphur deficiency must be carefully controlled such that the appropriate quantity of PGM-rich metallics are produced from matte separation. The present paper outlines continuous converter technologies that have been implemented in copper, and evaluates their potential for nickel converting. The challenges of producing a Bessemer matte to the required specifications are discussed. The economic and environmental driving forces, and the challenges of justifying a novel technology in place of productive existing equipment, are discussed.

Jan 1, 2005

By Bekir Karasu

Boron raw materials are amongst the most important natural sources for many industrial branches and their values become increasingly raised with the discovery of boron usage in many new technological fields. All the countries in the world are unfortunately not as lucky as Turkiye and USA where major boron deposits are mainly located. It is widely known fact that on one side, boron is very precious component with its technological importance, on the other; only its limited sources are available. Therefore, even its wastes have to be evaluated and regained. In the present work wastes of Etibor Kirka Borax Company of Turkiye were used in the production of opaque frits which was suitable for floor tile glazes. Standard and newly produced frit based glazes were applied on the pre-engobed floor tile bodies and single firing was employed. Final products were examined according to the certain standard tests and their microstructures were also investigated. All the results confirmed the evaluation of boron wastes in opaque floor tile glazes.

Jan 1, 2006

By A. Schönecker, P. Y. Pichon, B. Kraaijveld, Y. Meteleva-Fischer

"Ribbon-growth-on-substrate is a casting method, which offers a possibility to control heat flow, nucleation and subsequent crystal growth at the liquid-substrate interface. This technology allows for low-cost and high throughput shaping of silicon sheets with controlled crystal grain size and orientation for use in solar cells. In this work, sheets of silicon- metal silicide composite materials were produced and their microstructure was studied. It was shown that depending on the relevant phase diagram and casting conditions, a micro/nano-sized eutectic structure of the casted sheet can be formed. Such composite materials possess properties promising for various applications in energy generation, storage and conservation. The advantages, potential and challenges of the ribbon-growth-on-substrate technique for production of composite sheet materials as well as novel areas of application for such materials are discussed.IntroductionThe Ribbon Growth on Substrates (RGS) process is well known in the solar industry as a process to produce multicrystalline silicon wafers. An industrial size pilot production line for continuous casting of silicon wafer was developed by RGS Development B.V. in the Netherlands (Figure 1). A comprehensive review of this technology and properties of the produced silicon wafers were reported by Schönecker et al [1]. The principle of the RGS process is explained in Figure 2. The relatively cold substrate extracts the crystallization heat from the liquid silicon in the casting frame. This results in the growth of a silicon ribbon (Vc) in contact with the substrate. When the substrate (Vp) is transported from the casting zone into the cooling section, the crystal growth stops, the wafer can be removed and the substrate can be re-used. Last few years large work was done on the industrialization and market development of RGS wafers for the solar industry. Part of this work was discussed by Schönecker et al [2]. Although there is still a good perspective on the middle and long term solar market for the RGS wafers, the current market situation was found to be unfavorable for new entrants."

Jan 1, 2014

By V. V. Kutumbarao, M. T. Nimje, G. Balasubramanian

Wastes from the aluminium industry such as red mud from the alumina refinery, fly ash from the captive power plant and spent pot lining from the smelter, have been successfully converted into glass-ceramic products. The process involves addition of a small quantity of glass former along with traces of nucleating agents to aid crystallization, to a specific mixture ofred mud, fly ash and spent pot lining, followed by melting at around 1300°C and vitrification by cooling. The resultant glass is then converted into a glass- ceramic by a suitable heat treatment at around 700 - 750°C. The glass-ceramic products show excellent wear resistance, besides possessing an aesthetic appearance. The major application foreseen for such products is as decorative tiles in the building industry.

Jan 1, 2000

By Magnus Ek

After the installation of three new converters as part of the recent expansion of the Rönnskär smelter completed in 2000 work continues to further improve the converter operation. The converter upgrade led to an increase in blister copper taps from 150 tons per batch to more than 300 tons. The total cathode copper production increased from 130,000 tons in 1999 to 230,000 tons in 2001, the first year in full production. In recent years focus has been to improve operating practise, maximize the blowing time, extend the converter campaigns hence to reduce the specific brick consumption and improve the converter slag composition.

Jan 1, 2005

By Forsén. O.

In this ?paper practical solidification of anodes containing nickel, arsenic, antimony and bismuth is compared with the equilibrium? diagrams and kinetic ?factors. In order to clarify the distribution of the impurity elements in the anode the structures were studied after the solidification and also after the electrolysis of anodes. This examination was carried out with optical microscope, scanning electron microscope and electrochemical measurements. All the nickel is remaining metallic in the copper matrix during the solidification and therefore nickel is dissolved in the electrolysis at all oxygen contents, when the nickel content is 0.25 wt-% or less in the anode. The practical .solidification mechanism of the anodes, when the nickel content exceeds 0.25 wt-%, proceeds by the crystallization of nickel oxides. In oxygen containing copper anodes nickel oxide is verified to crystallize together with antimony in certain conditions and to form a micaceous compound (3Cu2O?4NiO?Sb2O5), which may build up a very harmful floating slime in the electrolyte. Arsenic is strongly enriched along the phase boundaries in oxygen free copper anodes. An intermetallic compound Cu3As is formed when the amount of arsenic in the anode. exceeds 0.7 wt-%. This compound is more noble than the copper matrix. This means 'that a selective dissolution of copper-arsenic compounds takes place. The copper matrix dissolves more strongly than the grain boundaries. The solidification structures of oxygen free bismuth containing copper anodes show clearly the influence of bismuth. Thin bismuth films which are less .noble than the metallic copper matrix, are formed during the solid1ficatton process. As a result of this the?grain boundaries are dissolved faster than the copper matrix.

Jan 1, 1987

By Thomas R. Wildeman

Experimental methods for studying vapors over solid minerals are reviewed and an especially developed method using atomic absorption is described. The method is used to study vapor pressures over Te. Ag, Au, Ag2Te, and AuTe2 from 250°C through 10S0oe. Vapor pressures observed and, concurrently. sintering properties are significantly altered by the form of the solid. The vapor pressures of the tellurium compounds reveal complex processes occurring on the surfaces of the solids. The data given also point out a method of recovering precious metals from their telluride minerals w

Jan 1, 1987