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By Ditze A., C. Scharf

Magnesium type 1 - scrap can be remelted without flux in the presence of different sulfur containing protective gases. Beside the draw back in the use of these gases, that either are contributing to the global warming potential (SF6) or are poisonous (S02), residues like dross and crucible sludge are produced. Dross and sludge now a days must be utilized. Partly these byproducts can be used in the aluminum industry and partly for desulphurisation of hot metal and steel. Another possibility is melting of dross and sludge with flux for the production of a secondary magnesium alloy. Then again residues are generated that must be processed. Therefore, the whole material cycle has to be considered to decide which kind of utilization practice is optimum. Based on experiments this question is discussed and the material balances for fluxfree melting, melting with flux and fluxfree melting plus other utilization of the residues are presented.

Jan 1, 2000

By Gaifeng Xue, Lei Zhang, Aimin Duan, J. Y. Hwang, Lina Wang

"The removal of chemical oxygen demand (COD) from coking wastewater was experimentally investigated using a three-dimensional electrode reactor. The experimental results showed that the refractory organics in coking wastewater can be effectively removed by this process, and COD removal efficiency was affected by the operating parameters, such as electrolytic retention time, particle electrode dosage, initial pH, current density, aeration amount and electrical conductivity. The experimental results show that the three-dimensional electrode could have a COD removal efficiency of more than 60% and a running cost of no more than 6 YUAN (RMB)/t. This indicates the great potential of a three-dimensional electrode reactor in engineering applications as an advanced treatment methods for coking wastewater.IntroductionCoking wastewater is generated from coal coking, coal gas purification, and by-product recovery processes of coking; it is composed of phenolic compounds, heterocyclic compounds, polycyclic aromatic hydrocarbons, ammonia, cyanide, polycyclic nitrogen-containing aromatics, acyclic compounds, etc. Most of these constituents are refractory, poorly biodegradabile, toxic and carcinogenic [1-3]. Currently, coking wastewater is usually treated by different forms of A/O biological nitrogen removal processes as the primary treatment means, but the aforementioned processes are not efficient enough to meet the requirements of the National Discharge Standard in China (GB13456-1992). According to the continuous requirement on improving environmental protection for the coking industry (revised 2008), increasing wastewater utilization ratios and reducing the discharge of effluent in the coke industry have to be implemented for cleaner production and sustainable development. Therefore, advanced technologies need to be developed to treat coking wastewater and reutilize the product as industrial cooling water, which would be one of the best choices to achieve zero discharge of wastewater and reduce water consumption per ton of steel produced. In this study, a three-dimensional fluidized bed electrode reactor was adopted for the advanced treatment of coking wastewater, and the effects of operating conditions, including particle dosage, initial pH, current density, supporting electrolyte, as well as aeration amount on the COD removal rate, were investigated. Its running costs were also estimated."

Jan 1, 2012

By Maria Salazar-Villalpando, Todd H. Gardner

"Efficient utilization of CO2 can help to decrease global warming. Methane reforming using carbon dioxide has been of interest for many years, but recently that interest has experienced a rapid increase for both environmental and commercial reasons. The use of CO2 provides a source of clean oxygen, which eliminates the need for costly oxygen separation plants. The product of dry reforming is useful syn-gas, which can be used to generate electrical power in a SOFC or in the production of synthetic fuels (hydrocarbons and alcohols). Hexaaluminate catalysts prepared at NETL may represent a product that can be utilized for the conversion of CO2 to syn-gas. In this work, transition metals dispersed in barium hexaaluminate have shown to be promising new catalysts for dry methane reforming. In this investigation, a series of BaNixAl12-yO19-d catalysts with varying Ni content were prepared by co-precipitation followed by calcination at 1400°C. CO2 reduction by dry methane reforming was carried out to determine catalyst performance as a function of temperature and carbon formation was also quantified after the reforming tests. Results of catalysts characterization, dispersion and surface area, were correlated to catalytic performance.IntroductionEfficient utilization of CO2 can help to decrease global warming. Methane reforming using carbon dioxide has been of interest for many years, but recently that interest has experienced a rapid increase for both environmental and commercial reasons. The use of CO2 provides a source of clean oxygen, which eliminates the need for costly oxygen separation plants. The product of dry reforming is useful syn-gas, which can be used to generate electrical power in a SOFC or in the production of synthetic fuels (hydrocarbons and alcohols). The dry reforming reaction has been known for a long time. Recent publications have reported studies over several catalysts. For example, the CO2 reforming of CH4 over mesoporous nanocrystalline zirconium powders (ZrO2–3%M2Ox; M: Ce, La and K) at 700ºC have shown methane conversion up to 60% (1). Similarly, the effect of Ni content (1–12 wt%) on the surface and catalytic behavior of bimetallic PtNi catalysts supported on ZSM-5 for reforming of methane with CO2 has been studied and report shows a maximum conversion of 16% and catalyst deactivation was observed during the first hour of time on stream (2). In another report, (3) Ni/a-Al2O3 catalyst was tested for syn-gas generation at 750ºC. The maximum methane conversion was 25%."

Jan 1, 2008

By Metehan Erdogan, Ishak Karakaya, Fuat Erden, Emre Ergül

"The FFC Cambridge process was suggested as a promising Si production technique for the expanding solar energy industry. Direct electrochemical reduction of bulk SiO2 plates and porous SiO2 pellets in molten CaCl2-NaCl salt mixture were investigated at 750°C by applying 2.8 V potential difference. The produced Si powder was brown and found to be contaminated by the Ni and stainless steel plates used as the cathode contacting materials. The reduction rates of the bulk SiO2 plates and porous SiO2 pellets were compared from variations of current and accumulative electrical charge that passed through the cell during the electrochemical reduction. The amorphous bulk SiO2 plates were reduced slightly faster than porous pellets of crystalline SiO2. The overall reduction potential of SiO2 pellets against the graphite anode at 750°C in molten CaCl2-NaCl salt mixture was determined as 2.3 V by cyclic voltammetry. This potential was supported by calculations.IntroductionMetallurgical grade Si cannot be directly used in electronic industry and some intermediate steps are required to produce industrial solar grade silicon (SOG-Si). A promising alternative solar grade silicon production technique is the FFC Cambridge Process [1]. Production of Si by electrochemical reduction of SiO2 at 850oC in molten CaCl2 electrolyte was first studied by Nohira et.al. [2]. In their study; Si formation was observed on bulk SiO2 cathodes after 1 hour of electrolysis. Complete electrochemical reduction of porous SiO2 pellets was first reported by Jin and his coworkers [3]. The mechanism of electrochemical reduction of SiO2 to Si in molten CaCl2 was explained in another study [4]. Reduction rates of bulk SiO2 and porous SiO2 pellets were also compared previously and it was found that reduction rates for bulk plates were higher [5]. Furthermore, it was reported that mixing Si into porous SiO2 pellet increased the reduction rate [5]. Mo [2, 4-7], Ni [3, 8, 9] or Si [6] were used as cathode contacting materials in various studies. Yasuda et. al. [6] produced Si with 99.80 % purity using Si plates as cathode contacting material to reduce metal contamination."

Jan 1, 2012

By Zhihe Dou

SHS reaction system has advantages of heat flux density, energy concentration and reaction speed, with sufficient conditions in thermodynamic and kinetic reaction. This paper invented a new technology of SHS metallurgy of preparing melting point alloys and refractory compounds using its own chemical energy. SHS-leaching process for preparing nano boron powder or ultrafine boride powder and SHS-casting process for preparing titanium-based alloy and immiscible alloy were studied. The results indicate that highly active boron powder of greater than purity of 93%, particle size less than 100nm and purity greater than 98.5%, particle size less than 400nm REB6 can be prepared. With SHS-Casting process, the oxygen content of less than 0.59% ferrotitanium, oxygen content of less than 0.5% titanium alloy and ?40-80*100mm large size of CuCr, Cu-Fe alloy ingots were prepared. This technology has greatly enhanced the thermal reduction method added values of preparing metallurgical products and its competitiveness.

Jan 1, 2014

By Yong-ming Chen, Chao-bo Tang, Yun Li, Long-gang Ye, Sheng-hai Yang, Hao-tian Xue

In order to achieve high recovery of Cu and Co during cobalt-bearing copper sulphide ore smelting process, reducing agent (coke) and sulphidizing agent (pyrite) were added into molten smelter slag for reducing-sulphidizing smelting to product Cu-Co matte. Effects of reductive atmosphere, pyrite dosage, smelting temperature and smelting duration on Cu, Co, Fe distribution behaviours were investigated. The results show that the distributions of Cu and Co are mainly enriched in Cu-Co matte, and the distribution ratio, LCu and LCo, improve with increasing of coke amount or pyrite addition, whereas above 6 wt.% coke or 20 wt.% pyrite, Cu and Co tend to transfer from matte to cleaned slag. A properly high temperature(1300) and smelting duration(3h) are beneficial to the enhancement of the distribution ratio of valuable metals, and under the given set of conditions, LCu > LCo generally. However, an undesired high Fe contents in matte limit further increase of LCu and LCo.

Jan 1, 2015

By S. C. Sharma

The aluminium matrix composites with ceramic dispersoids can be separated by density difference concept. In the proposed work composite scrap is recycled using an oil fired furnace. The scrap is melted in the furnace and temperature is maintained below 740 degree centigrade. Because of the density difference the lighter dispersoids will float and heavier dispersoids will settle down. The clean melt is separated be removing the floating and settled disperssoils, and then filtering using ceramic filters.

Jan 1, 1995

By S. M. Copley, M. Yankova, E. Y. Yankov, J. A. Todd

"Nanophased coupled growth structures, with spacings of -10 nm, have been observed in banded microstructures produced by laser melting hypoeutectic Ag-Cu alloys. These coupled growth structures comprised a Cu-rich phase of width - 1 nm and a Ag-rich phase of width - 9 nm. In this paper, microstructural observations of nanophased coupled growth structures in hypo eutectic AgCu alloys are presented. Laser beam velocities for the transition from banded to microsegregation free microstructures are modelled and compared with experimental values. Models are presented to show that, at a critical undercooling, initial growth of a Ag-rich, metastable, extended solid solution is rapid but slows to a halt as copper is partitioned into the liquid at the solid/liquid interface. Following nucleation, the coupled growth structure then grows until the partitioned copper is consumed, at which point growth of the Ag-rich solid solution is again accelerated. This cycle then repeats resulting in banded microstructures comprised of 750 nm of the Ag-rich extended, metastable solid solution, followed by 250 nm of the coupled growth structure.1. Structural Studies of Laser Melted and Resolidified TrailsPresented here are observations of laser melted and resolidified trails in Ag-Cu alloys obtained at beam velocities ranging from 0.7 to 34 cm S·I. When the laser beam is scanned along the surface (positive x-direction) with a velocity Vb a melt pool with the shape given in Fig. 1a moves with the beam. The isotherms move with the velocity, Vi,. = Vb cos.p. Calculations employing the thermal analysis of Kou, Hsu and Mehrabian [1] for the beam velocities of this investigation and for the thermal properties of AgCu alloys, indicated that, .p, the angle between the isotherm velocity and beam velocity should be small at the surface where microstructural studies were made. This prediction was supported by observations of trail cross-sections. Based on these observations, and the calculations which include latent heat effects, the isotherm velocity for observations near the surface in our investigation was taken to be 27 cm S-I."

Jan 1, 1994

By Milton Manrique, Edgar E. Vidal, Patrick R. Taylor

"Ultrafine zirconium carbide powder has been synthesized using zircon concentrate and methane in a thermal plasma reactor. The effect of several experimental variables, such as power used and zircon particle size, on the conversion has been studied. A thermodynamic analysis of the possible reactions and stable compounds was performed. A mathematical model that describes the in-flight decomposition of zircon particles was developed based on a description of the temperature and velocity profiles calculated in the reactor. It was shown that the formation of zirconium carbide from zircon and methane is thermodynamically possible. Complete 'vaporization of zircon in the reactor is predicted when the particle size is below 45flm and the effective power entering the reactor is 15 kW. The powders were collected and characterized by XRD, SEM, TEM and chemical analysis using ICP. Results of the product analysis indicated the presence of zirconium carbide, zirconium oxide, silicon carbide and silicon oxide.IntroductionIn recent years there has been an increased interest in the production of nanometric sized powders of ceramic materials for use in advanced materials applications. One possible method to produce these powders is with a thermal plasma reactor, which offers high temperatures and fast quenching rates. This technology has been called - Thermal Plasma Synthesis - [1].Zirconium Carbide (ZrCx) has typical properties of transition metal carbides: elevated hardness - between alumina and diamond - a high melting temperature of 3420°C and high chemical stability at room temperature [2]. ZrCx has a Bl crystal structure with deficiencies in the number of carbon atoms in the cell with x between 0.6 and 1 [3]. Different methods have been used to produce ZrC, one method is by direct reaction of zirconium hydride or halide with carbon. Other methods used are direct reduction and carburization of zirconium oxide (Zr02) and reaction of metallic zirconium with a caburizing gas such as acetylene [3]. Recently small films of ZrC have been obtained using a sputtering device [4,5]. ZrC has been used in nuclear plants as a low neutron absorbing and high mechanical resistant refractory material and also as a constituent in cathodes made of UC-ZrC [6]. It is also used in the form of tubes, boats and crucibles to handle molten metals and as part of electronic devices used for thermoionic transducers. Recently ZrC has been used along with zirconium diboride (ZrB2) to produce composite materials [7,8]."

Jan 1, 1996

By Lan Li, Izaak Williamson

"The efficient separation and storage of CO2 from power plant flue gases can reduce the amount of CO2 released into the atmosphere and mitigate global warming. Potential candidates for industrial applications are solid sorbent materials. Crucial factors to control the efficiency of porous sorbent materials include the framework and pore structure, and the chemical and physical reactivity of CO2 within the pores. Computational modeling approaches, based on density functional theory (DFT) and van der Waals-DFT, have been applied to nanoporous solid – manganese dioxide a-MnO2. We found that the types and charges of cations as dopants in the a-MnO2 and the concentration of CO2 influence the structural features of a-MnO2, which control its CO2 selectivity performance within the flue gases.IntroductionCarbon capture and storage is a technique to separate large quantities of CO2 from power plant flue gases before being released into the atmosphere. Porous solids are a potential candidate as sorbents to “trap” CO2 through chemical or physical adsorption on their porous surfaces[1]. Such separation efficiency is determined by the size and shape of its pores and by the interaction between the porous surface and the gas adsorbates. The incorporation of cations into the pore can act as a means of structural support and alter the pore diameter to be comparable to the kinetic diameter of the gas adsorbate, such as CO2.A porous solid of particular interest for CCS is manganese dioxide a-MnO2, an octahedral molecular sieve (OMS) composed of edge-sharing MnO6 octahedra that are linked into a nanoporous framework[2]. The framework consists of (1×1) and (2×2) tunnels, referred to as OMS-2. Due to the larger tunnel size, cations and gas adsorbates prefer to reside along the (2×2) tunnel axis of the OMS-2. As seen in Figure 1, a potassium cation K+ is located in the (2×2) tunnel, known as cryptomelane-type MnO2. Its pore diameter of ~ 4.6 Å gives it a good CO2 selectivity performance, because the diameter is comparable to the kinetic diameter of 3.3 Å for CO2[3]. Alternatively, replacing potassium K+ with other cations, e.g. barium Ba2+, sodium Na+ or lithium Li+, in the OMS-2 tunnel is of great research interest, due to the effects of their concentrations, types and charges on the CO2 selectivity efficiency and sorption hysteresis phenomenon[2,4]."

Jan 1, 2014

By Liu Chunpeng

The new technological process developed is by means of thermal plasma arc smelting to obtain high grade Ni matte directly from Ni-Cu concentrates containing 6-7% nickel and 3-8% sulfur. In comparising with conventional smelting and converting processes the plasma arc smelting process has many advantages over conventional processes, such as lower energy consumption, lower capital investment and free from SO, pollution by transforming the sulfides into elemental sulfur with microwave irradiation under controlled oxygen potential, moreover, the process is simple and easily controlled due to less magnetite troubles in the operation. Therefore, this new technological process can be used as an alternative way to conventional process for Ni-Cu concentrate smelting. The main economical technical index is summarized in Tabal 1. Table 1 Main Ecnomic-technical Index

Jan 1, 1993

By Hong N. Vu, Jitka Jandova

"Gypsum and limestone methods were examined in this study to process zinnwaldite wastes originating from dressing Sn-W ores mined in the Czech Republic. These wastes containing 0.20-0.30% Li and 0.10-0.20% Rb were subjected to magnetic separation to obtain a zinnwaldite concentrate with 1.36% Li and 0.94% Rb. It was observed that processing of the zinnwaldite concentrate with gypsum resulted in almost 96% recovery of Li into aqueous liquors, whilst rubidium extraction was only 25%. At the same time, it is possible to extract almost 92% Li and Rb from the identical zinnwaldite concentrate if the concentrate is processed by limestone method. Lithium carbonate, a final product of both methods was recovered from the refined sulphate solution using K2CO3 as a precipitation agent and/or from unrefined hydroxide solution using gaseous CO2. In the continuation of this study, rubidium will be separated from carbonate solutions after Li2CO3 precipitation as RbAl(SO4)2, an intermediate for Rb2CO3 production. IntroductionLithium is used as an alloying constituent in lightweight alloys, as a heat transfer medium in nuclear reactors and as a component in primary and secondary batteries. With the development of a new generation of electric vehicles, the lithium demand will dramatically grow. Lithium chemicals find extensive application in many industrial branches such as metallurgical, glass, ceramic and pharmaceutical industries. Rubidium compounds are predominantly used in psychiatry and medicine, in magneto-optic modulators, solid-state lasers, phosphors and components of electrolytes for fuel cells. The four most important lithium minerals are amblygonite, spodumene, petalite, and lepidolite. Spodumene LiAlSi2O6 (6.0-7.5% Li2O) and petalite LiAlSi4O10 (3.5-4.5% Li2O) belong to aluminosilcate minerals. Lepidolite (Li.Al)3(Al.Si)4O10(F.OH)2 (3.30-7.74% Li2O), lithium mica, is the most important representative of the mica minerals, a subgroup of the aluminosilicates. It frequently contains 3–5% Rb2O and eventually caesium. Zinnwaldite, which has the general formula K(Li.Al.Fe)3(Al.Si)4O10(F.OH)2 (2-5% Li2O), is regarded as a variety of lepidolite with a high iron content. Commercial amblygonite is a complex phosphate (Li.Na)Al(F.OH)PO4 (up to 9.88% Li2O), however, its deposits have not been commercially exploited because of their small size. Natural brines with a high lithium chloride content are important in the industrial production of lithium [l]"

Jan 1, 2008

By A. Dell’Era, M. Pasquali, C. Lupi

"An electrochemical cell has been designed to treat very diluted cobalt solutions, i.e. those deriving from recycling processes of lithium-ion batteries. A reticulated vitreous carbon sponge was used as cathode and a Pt-coated Ti net as anode. A controlled potential electrolysis has been carried out in a solution flowing in the cell and maintained at a constant pH of 6.5. Considering the cathode dimensions (10.0 cm * 10.0 cm * 1.25 cm), rather high volumes of solution (>1 litre) can be treated with flow rates up to 1.6 l/min. The process yield is obviously related to the solution concentration; it has been observed that, starting with a solution containing 200 ppm of Co2+, the yield is initially ~35-40%, but it decreases to ~20% when 80% of the initial cobalt content has been electrowon. The yield increases up to ~50% if the carbon electrode is coated by cobalt. The conditions allowing a fast and complete removal of cobalt are outlined. Introduction Industrial liquid effluents containing heavy metal ions arise not only during hydrometallurgical processing, but also in many sector of chemical industries utilizing metal catalysts and process reagents. These waste solutions containing low quantities of metallic ions can be treated by chemical precipitation, solvent extraction, ion exchange, etc. before final discharge. All these techniques could be efficient for complying the aqueous effluents with the severe rules related to the environmental impact, but they can not directly produce metals. Particularly the chemical precipitation presents two main drawbacks, huge amount of sludge prodction and reagent costs to produce this useless and sometime dangerous sludge that have to be considered. Electrochemical technologies can be used for the treatment of effluents polluted by metal ions, showing the following advantages in comparison with other processes: 1. recovering of the polluting substances in metallic forms, with subsequent reusing; 2. absence of process slag, which should be subsequently disposed of. In this work an electrochemical reactor with a reticulated vitreous carbon cathode and a platinated titanium net anode has been designed and utilized for removal Co from waste aqueous solutions. Porous materials have been used as electrodes for this cell, as their high specific surface area favours the treatment of these low metal content solutions (1-7). This kind of electrodic material presents very interesting chemical-physical characteristics such as: low density, low thermal expansion and high electrical and thermal conductivities; particularly the reticulated vitreous carbon (RVC) presents a very elevated void volume, rigid structure, good resistance to temperatures in non-oxidizing environments and very low resistance to fluid flow."

Jan 1, 2008

By M. G. Basavaraj, S. Sarkar, G. S. Gupta, P. D. Patil

"Previous experimental study on raceway size hysteresis on two-dimensional cold model showed that the inter-particle and wall-particle friction had a very large effect on the raceway size. Existing literature correlations for raceway size ignore the frictional effects. It has also been shown in the present study that their applicability to the ironmaking blast furnace is questionable. To take into account the effect of friction on the raceway size a stress analysis has been done for the raceway region. Two-dimensional fluid flow equations under turbulent conditions have been developed and solved computationally in order to get the pressure forces. The frictional forces were obtained in terms of stresses. To predict the raceway size a force balance was done for the raceway zone considering the pressure force, the frictional force and the bed weight. The resulting equations from the force balance are able to describe the raceway hysteresis phenomena reasonably well along with the raceway size. A two dimensional experimental set up has been fabricated in order to validate the computer predictions. Predicted values agree well with the experimental values.IntroductionWhen a high velocity blast of air is introduced into a packed bed through a tuyere, a cavity is formed in front of the tuyere. This cavity, formed in the iron-making blast furnace, is called the raceway. Coke tumbles down and bums in this raceway, generating heat and reducing gases for the iron-making process. The raceway is responsible for producing most of the reducing gasses in the blast furnace. In addition, the size and shape of the raceway determines the movement of solids within the blast furnace, the distribution of gases and liquids (slag and metal), setting the location where the primary chemical reactions occur and the temperature profile in the lower part of the blast furnace.Due to the importance of the raceway, many investigators l - 6 have studied it and have predicted the raceway size using the empirical correlations based on experimental (hot & cold) and mathematical models. A number of correlations have been reported in the literature to predict the raceway size by various investigators3 - 6 which are different to each other. Each of the correlations shows a different dependence of raceway diameter (DR) on bed height, particle size, solid density, bed voidage and blast velocity. None of the correlations includes the effect of solid stresses on the raceway size and shape. The magnitude of these stresses will depend on the bulk solids properties (internal angle of friction, wall angle of friction) and the bed dimensions."

Jan 1, 2001

By M. A. Barron, D. Y. Medina, R. T. Hernandez, I. Hilerio

"Chromium Nitride (CrN) thin fihns were deposited on steel AISI 316 substrates with reactive magnetron sputtering method. CrN films were produced under two different conditions. In the first one, the substrate was heated by a d.c. source. At the second coating was applied a negative substrate bias voltage. X ray diffraction, quantitative energy dispersive and scanning electron microscope, were employed to characterize their phases, chemical composition and microstructure. Additionally microhardness was evaluated using a microhardness tester. The results show that the phase formation of CrN thin films in the first case (with temperature) is better. Both coatings presented homogeneous surface. Their compositions shows differences though that gases flow are same. In attention to their hardness, presents an increment if it's compared with hardness substrate.Nomenclature.P Ar =Argon gas pressure during coating.PN2 = Nitrogen gas pressure during coating.Ts = Substrate temperature during coating.T f = Coating melting temperature. (CrN = 1050°C).E=Potential difference.t =Coating time.P=Target power (Cr) in magnetron sputtering de.HV = Vickers hardness.F = Applied charge.d= Average length of longitude of the two diagonals (mm)Introduction.Wear causes losses in materials surface, generating that components of mechanical systems suffer irreversible changes in their properties, causing a faulty operation of the system. It is important to control their effects, measuring and interpreting their causes clearly."

Jan 1, 2013

By Lei Zhang, Shining Chen, Lina Wang, Pu Liu, Benquan Fu, Jiannyang Hwang

A three-dimensional (3D) electrode reactor combined with Fenton reagent was used for advanced treatment of coking wastewater from secondary biological treatment. Effects of some key factors on total organic carbon (TOC) removal rate were investigated, and the results were compared with those of the common three-dimensional electrode reactor. Experimental results showed that TOC removal rate could reach 51.7%, when optimal operating conditions were as follows: initial pH value 3.5, H2O2 dosage 17.6mmol/L, reaction time 90min and FeSO4·7H2O dosage 3.5mmol/L. Analytical results from UV absorption spectra indicated that the organic substances in the coking wastewater were well degraded by this system, which provided good experimental basis for the practical application of this process in the treatment of coking wastewater. This can be meaningful for the treatment of other kinds of wastewater.

Jan 1, 2015

By J. S. Lee

A new high performance adsorbent is synthesized by the sol-gel method and applied to the removal of cadmium and mercury ions from aqueous solutions. Adsorbents based on metal oxides have been developed by immobilizing chelating molecules on the surface of the existing metal oxide networks and show ability for selective metal extraction from aqueous solutions. However, efficiencies of such adsorbents are limited due to low ligand density, and difficulty in pore accessibility. These difficulties are circumvented by synthesizing adsorbents using the sol-gel technique. In one example to be discussed, the sol-precursor possesses an organic moiety that binds cadmium, mercury, and copper ions. The capacities of 1.98mmol Cd(II-/gm and 6.40 mmol Hg/gm of this adsorbent are considerably higher than those of adsorbents prepared by the ligand immobilization technique. The scope of this paper is to discuss the development of the new adsorbent and its applications for cadmium and mercury removal from aqueous solutions.

Jan 1, 1999

By Mingmei Zhu, Xin Qiu, Xiaofei Dou, Yu Wang, Tiancheng Lin, Bing Xie

In this study, the slag forming route of the single-slag steel melting when smelting medium phosphorus hot metal was investigated. The CaO-SiO2-FeO-MgO-MnO-P2O5 as hexahydric slag system was adopted in the converter. The effect of slag composition on liquidus was calculated by FactSage, the isogram of phosphorus distribution ratio was calculated by using the regular ion solution model, combining these two tasks, the theoretical slag forming route was obtained. Through experiments, the actual melting point ofthe corresponding components on theoretical slag forming route was obtained, in this way, the theoretical slag forming route was confirmed. Then, the theoretical slag forming route was applied to industrial test in a 210t BOF. After using the new slag formating route, the dephosphorization ratio was increased 3.6% while the auxiliary materials consumption was reduced, and the cost of steelmaking was reduced.

Jan 1, 2015

By O. G. Yeremin

The Joint Venture "Inter-S" jointly with the Gintsvetmet Institute have developed a technology for manufacturing of sulphoconcrete and sulphoasphalt. The sulphoconcrete manufacturing technology comprises preliminary production of modified sulphur, which is blended in liquid form at a temperature of 120°C with an inert material preheated to the same temperature. The second promising area for the use of sulphur is partial substitution of modified sulphur for more expensive bitumen. The sulphoasphalt manufacturing process comprises preliminary production of a sulphur and bitumen mixture with a sulphur content of 30% to 40%, which is then blended with inert materials using conventional techniques. Sulphoasphalt manufactured at a full-scale plant meets all requirements set to its strength properties for road paving. Technology has been developed for production of high-purity sulphur based on rectification of liquid sulphur in a packed column. A commercial-scale plant with a capacity of up to 15 tonnes per year for production of sulphur with an impurities level of about 110-6 % by mass has been put into operation.

Jan 1, 2006

By Christian Bernhard, Mario Hartl, Susanne K. Michelic

"One aspect of an efficient process and product optimization of the liquid steelmaking process is the understanding of reactions and interactions between the components steel, slag and nonmetallic inclusions. The present paper focuses on a fundamental study of this topic by combining the powerful methods of thermodynamic modeling with systematic experiments on a laboratory scale and subsequent SEM/EDS analyses. The modeling aspect is addressed by the commercial software FactSage 6.1; laboratory experiments are performed for a low-alloyed, Ca-treated carbon steel combined with varying slag compositions. The consequent SEM/EDS analyses provide a detailed insight into the inclusion landscape which offers a strong tool for characterizing the modification of inclusions. In the present study the combination of these methods is mainly applied to oxides, due to their crucial influence on the final product quality, thus giving important indications for further optimizing the secondary metallurgy processes.IntroductionIn recent years, the range of application for steels has been enlarged continuously; also resulting in extreme surrounding conditions combined with considerable stresses for the material. This trend is directly linked with higher demands on the properties of steels. In order to optimize the final product quality, the cleanness of steels is an important criterion. For this reason, the broad topic ""Steel Cleanness"" has become one of the main research points at the Chair of Metallurgy. Next to the continuous optimization of methods for the characterization of cleanness, the primary aim is to combine thermodynamic modeling and laboratory experiments in order to describe the changes in inclusion landscape under different conditions.The steel cleanness can particularly be influenced in the processes of secondary metallurgy. In different processes the reactions and interactions between the components steel, slag and nonmetallic inclusions (NMI) are essential for the final inclusion landscape. Consequently, the understanding of the occurring reactions is a fundamental aspect for further development and process optimization. In secondary metallurgy especially oxide-slag systems consisting of the components Ca0-Ah03-Mg0-Si02, which significantly influence the modification of NMI, are of importance. Several works dealing with the interactions of oxide non-metallic inclusions with different slag systems have been published in the last years [1-4]. In order to observe the dissolution of oxides in different slag compositions a Laser Scanning Electron Microscope is frequently used. A very detailed study on the ternary system Ah03-Ca0-Mg0 and its subsystems was also done by De Aza et al. [5, 6]."

Jan 1, 2011