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By Huaming Yang

The vanadium-doped SnO2 nanoparticle was synthesized by the co-precipitation reaction and subsequent calcination from the vanadium(III) chloride and tin(IV) chloride. The crystal size, pore size distribution, micrograph and properties of the nanocrystalline powders were examined by differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction (XRD), desorption isotherm (Barrett-Joyner-Halenda method) and transmission electron microscopy(TEM). Thermal treatment of the precipitate powder at 600°C led to the formation of V -SnO2 nanoparticle of -10mm in crystal size. Most of the pores in the nanoparticle are about 5~15nm in diameter. Effect of doped vanadium on the crystal size of the nanopartic1e was discussed.

Jan 1, 2003

By Xin Zhang, Mengqi Li, Hongxu Li, Xinrong Zhang, Hao Bai, Ning Li

"Organic Rankin Cycle (ORC) is an effective technology to transform low-grade energy resource into electricity. In this paper, based on thermodynamic principle, considering the waste heat resource lower than 120°C, thermodynamic properties of ORC with working fluids ofR245fa, mixed R21/R245fa and mixed Rl52a/R245fa were assessed. The results show that high evaporation temperature contributes to improved system performance. The Rankine Cycle that uses R21/R245fa can increase net cycle output, thermal efficiency and exergy efficiency by 3.02%, 2.35%, and 4.44%,respectively, as compared to that with pure R245fa. When using Rl52a/R245fa as working fluid, the net cycle output can increase by 3.83% at most, while the thermal efficiency decreases by 8.7%. These results indicate that R21/R245fa has a good advantage in improving the cycle thermodynamic performance.IntroductionOrganic Rankine cycle is usually used for low temperature power generation, and is applied to the conversion of geothermal energy, low-temperature solar energy, ocean thermal energy and industrial low-temperature waste heat etc. Traditional Rankine cycle is quite mature already, however, organic working fluids would affect significantly the general efficiency of the entire thermodynamic system. Thus, selection of proper working fluids and development of new highperformance cycle is becoming important."

Jan 1, 2013

By B. Q. Li, H. C. de Groh, X. Lu

"A fully 3-D, transient finite element model is developed to represent the magnetic damping effects on complex fluid flow, heat transfer and electromagnetic field distributions in a metallic melt. The model development is based on our in-house finite element code for the fluid flow, heat transfer and electromagnetic field calculations. The numerical model is tested against numerical and experimental results for water as reported in literature. Various numerical simulations are carried out for the melt convection and temperature distribution with and without the presence of a transverse magnetic field. Numerical results show that magnetic damping can be effectively applied to stabilize melt flow, reduce turbulence and flow levels in the melt and over a certain threshold value a higher magnetic field resulted in a greater reduction in velocity. Also, for the study of melt flow instability, a long enough running time is needed to ensure the final fluid flow recirculation pattern. Moreover, numerical results suggest that there seems to exist a threshold value of applied magnetic field, above which magnetic damping becomes possible and below which the convection in the melt is actually enhanced.1. INTRODUCTIONThe imposition of a DC magnetic field on a moving, electrically conducting fluid, such as molten metal or semiconductor melt, produces an opposing Lorentz force that results in a reduction of flow velocity in the liquid. This effect has been explored in both the semiconductor and metals industries to control natural convection and/or surface tension induced Marangoni convection as well as thermally induced flow instability during solidification processing of these melts [1-6]. A mathematical model can be of great use in developing both fundamental understanding of the fluid-magnetic field interactions in these magnetically-assisted processing systems and basic guidelines for process design, control and optimization.This paper presents a 3-D mathematical model for magnetically damped fluid flow and heat transfer in a melt cavity, which is useful for interpreting results for unidirectional solidification processes at slow solidification rate, and some preliminary results concerning the magnetic damping effects on the flow instability in the melt. The model development is based on the finite element solution of the Navier-Stokes equations, energy equations and equations for induced electric field. The model is tested against reported results and is then applied to study the fluid flow and thermal distribution in the metallic melt with and without an external magnetic field."

Jan 1, 1999

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 Na Wang, Chao Du, Yao Zhang Shuqiang Jiao, Hongmin Zhu

"Na2NbAlO5 was synthesized using Nb2O5 and NaAlO2 as raw materials in molten NaCl-CaCl2 by a solid reaction. With an addition of sodium into the melts, Na2NbAlO5 was subsequently reduced to form NbAl3 intermetallic compound with a particle size of 50-300nm.IntroductionThe intermetallic compounds of niobium aluminides have been a subject of research interests as high temperature materials because of their properties such as high melting temperature, large specific strength at elevated temperature, good resistance to high temperature oxidation, low density and large ductility [1,2]. They are applicable for turbine blades in aircraft engines and stationary gas turbines [3,4].In recent years, the methods of powder synthesis have been widely discussed. There are many methods to synthesis intermetallic compounds such as conventional melting and solidification [5], powder metallurgy [6,7], reaction sintering [8] and reaction sintering with prior mechanical activation [9,10]. There is a prominent weakness in such methods that they use metal to produce intermetallic compounds by the means of diffusion reaction. Although the metal can diffusion sufficiently, it is still hard to avoid maldistribution of the constituents which impairs the properties of the materials."

Jan 1, 2012

By Jie Ma, Bo Wang, Jieyu Zhang, Jian Zhao, Zheng Chen

"In this paper, solidification process of steel ingot was simulated by ProCAST software, based on cellular automaton-finite element (CAFE) model. A 22 t steel ingot was divided into continuous small zones (100x150x180 mm) in radial direction, then the temperature field, shrinkage cavity and porosity, particularly, the microstructure were simulated. The results show that: there was a columnar-to-equiaxed transition in microstructure on radial direction. Zones, closing to the center of the ingot, had a more developed and fined equiaxed zone, while zones closing to the periphery of the ingot had a more developed columnar zone. It indicated that temperature gradient has a great influence on microstructural morphology. Thus, the simulation results were highly agree with the experimental results, verifying the feasibility of this simulation method. It significantly reduces the time of simulation, and has important significance for predicting the microstructure of large steel ingot.IntroductionSolidification microstructure of steel ingot have a significant effect on the quality of the final steel products. Although many experimental works have been carried out in order to obtain the optimum condition for solidification process of continuous casting, it is also very desirable to establish mathematical models to simulate the evolution of solidification structure. The simulation methods can be divided into deterministic models and stochastic models, which have been developed rapidly over the last couple of decades. Cellular automaton method is one of the stochastic models. Rappaz and Gandin [1, 2], Nasatac and Stefanescu [3, 4] are the earliest researchers engaged in the this field. Moreover, Rappaz and Gandin simulated the solidification structure and CET (columnar grain to equiaxed grain transition) of metals using the CAFE method (cellular automaton-finite element method) for the first time [1, 2]. Recently, the CA (cellular automaton) model also considered the effects of fluid flow on the solidification process. Zhu, et al. [5-11] improved method of CA , they used the KGT model to describe the undercooling needed during the growth of the dendrite tip."

Jan 1, 2014

By R. T. Jr. Faria, H. Vargas, R. Toledo, S. Cosin, V. P. Souza

"With the purpose of decrease environmental impact, caused by industrial residues (just discarded in the environment) and clay extraction in the ceramic industry, sanitary ware wastes were incorporated into clay. In contrast, it is important to evaluate not only the technological essays but also gases emissions in the ceramic firing process. The pollutant gases emitted in ceramic with residues can be in much larger concentrations than that in a pure clay ceramic firing or, on the other hand, can decrease the pollutant gas concentrations. With the aid of thermal analyses and photo acoustical techniques it was observed that sanitary ware waste can reduce the C02 emission. The gas emissions were shown as in function of firing temperature from 300 DC to 1100 DC. In order to analyze phase transformations during the firing process, clay samples and wastes were both analyzed by x-rays fluorescent chemical analysis and x-rays diffraction.IntroductionResearch works on the structural and physical changes that wastes, mainly industrially produced, cause to the final ceramic product has been rapidly expanding in these last two decades. See, for instance references in [1]. In spite of these examples of a continuous effort to incorporate wastes into clay ceramic motivated by technical and economical advantages, environmental issues are still a matter of concern. However, the gas emission due to the clay firing process and its related atmospheric pollution may be enhanced as a consequence of an incorporated waste [2]. It is known that the firing of clay ceramics in conventional furnaces using fuels such as wood, charcoal, heavy oil and natural gas generates appreciable amounts of gaseous components, mainly carbon dioxide (CO2), carbon monoxide (CO) and methane (CH4). Additionally to the atmospheric pollution, these gas sets could be harmful to the human health and can corrode equipments [3,4]."

Jan 1, 2012

By Onwukamike, Onyedika G. O, Ogwuegbu M. O. C., K., Onyenehide C

A detailed mineralogical and elemental characterization of a lead (Pb) ore deposit from Ishiagu, Ebonyi State, Nigeria was carried out with XRD, SEM-EDX, and ICP-OES based mappingtechniques. The results show that the most dominant and valuable metal is lead (Pb = 95.02%, mass fraction). The main mineral is galena. Ilmenite and sphalerite occur as minors, which account for 2.71% and 0.80% respectively. Elements like Al, Ca, Mg, Ti, Na, Mn, Si and Sn occurred in trace amounts and are disseminated in the entire ore body.The surface and interrelations of the crystals were examined with x-ray mapping and the result shows the pattern of dissemination of the minerals within the ore body.

Jan 1, 2015

By Liya Bochkareva, David Hui, Sergey Eremeev, Maksim Kireitseu, Igor Nedavniy

The principal goal of the present paper is to demonstrate an application of modern software engineering tools for modeling virtual reality and molecular dynamics of novel nanocomposites. The main technical components of presented system are I) software and nanoengineering tools for modeling of virtual reality, molecular dynamic and 30 video images of novel diamcindscontaining nanocomposites and 2) Problem tracking system to be used during modeling of virtual reality. A computational scheme and software, which utilizes neural networks and/or Microsoft. Net technique was developed to predict properties of nano-structured materials and optimization and control of nano-devices. Developed software and IT nanoengineering tools can be used by both industrial and private single users. For commercial companies proposed technology may provide better cost-effective alternative to the existing solutions for nanoengineering and modeling their virtual realit. For private users (students, professors, and engineers) proposed technology and IT tools can provide simple and cost-effective solution for nanoengineering while studying, exploring virtual reality and modeling novel nanostructures and its properties leading to an innovation or a discovery. Because of using novel software and methodologies, users can easily operate proposed technologies by available computers and operating systems (Pentium III or IV). In addition, users can upgrade it by their own self-written models, if necessary. The proposed technologies could replace or be used along with technologies for modeling such as 30 max studio and others.

Jan 1, 2004

By James B. Pfeiffer

TETRA Technologies, Inc., has applied its HDSIM metals precipitation system to treat a waste stream containing scrubber blowdown and process water from a smelter operation. The combined stream contained cadmium, lead, selenium, arsenic and zinc, plus some iron and copper. Treatment requirements included meeting stringent mass flow limitations for specific heavy metals. The HDS ? system can reduce the arsenic from 600 ppm to less than one ppm. The process generates a dense sludge that can be reprocessed in a smelter, eliminating the liability associated with landfilling. Flow diagrams and process details are discussed.

Jan 1, 1994

By M. W. Wadsley

Despite the convenient subdivision of extractive metallurgy into hydro- and pyro- divisions, many flowsheets contain both types of process. When complex materials are used as feed, combinations of hydro- and pyro-metallurgical processes are even more common. Hydrometallurgy is used to treat many by-products and waste-products. (Bio-metallurgical processes may be considered to be a sub-set of hydro-metallurgical processes.) Combinations of the different processes in the Australian metallurgical industry are described. Selected international examples demonstrate that the use of combked processes is not a unique. Antipodean phenomenon. The motives for selection of combined pyre- and hydro-metallurgical processes in a flowsheet are examined.

Jan 1, 1994

By Milan Lj. Stamatovic

The hydrometallurgical recovery of zinc from recycled blast furnace dust from a steel plant (Smederevo Metallurgical Company - Yugoslavia) was investigated. The dust contained 22% Fe, 17% Zn and 0.2% Pb. X-ray diffractometry showed that the main components were hematite and magnetite, in combination with zinc oxide and a very low content of lead oxide. Individual particles were generally spherical and ranged in size from 10 to 150 microns; 63% were less than 33 microns in diameter. An effective hydrometallurgical approach proved to be by caustic leaching followed by electrowinning. Recovery of zinc in the form of zinc powder was over 90%. This powder can be used for the cementation of impurities in the conventional hydrometallurgical process for zinc production.

Jan 1, 1993

By Yuanbo Zhang, Qian Li, Helei Zhang, Heng Yu, Guanghui Li, Tao Jiang

"Large reserves of specularite iron ores have been found all over the world, which is characterized by high total iron grade, low gangues content, as well as low commercial price. However, it has not been widely used in sinter or pellet production due to its inferior sintering and roasting behaviors. It has shown that the proportion of specularite ores was increased as high as 40%~50% and good results was achieveed by using Composite Agglomeration Process (CAP), an innovative agglomeration process invented by Central South University. But the mineralization of specularite is still unknown during composite agglomeration processing. In this paper, the induration characteristic of specularite ore is studied by simulating CAP in laboratory, as well as microstructure analysis of CAP product. The results show that specularite pellet is mainly indurated through recrystallization of Fe2O3, calcium ferrite within high basicity sinters matrix interweaves with the recrystallized Fe2O3 on the surface of the pellet, which forms an integral microstructure, and ensures high strength of CAP product for ironmaking.IntroductionLarge reserves of specularite iron ores have been found all over the world, especially in Minas Gerais of Brazil, Xuanhua city and Anshan city of China, Elba island of Italy, St.Gotthard of Switzerland, Cumberland of Britannic, and so on. The specularite ores have a smooth surface, as well as a good crystallization and dense texture. When specularite is used to produce pellets, the specularite ore grains are difficult to adhere onto green ball due to its poor ballability. Moreover, specularite pellet requires high roasting temperature over 1300°C [1]. When specularite ore is used in sintering, the permeability of sintering bed gets bad and the quality of sinter is diminished. The practice in a few sintering plants finds that the output and strength of sinter decrease with the increase of specularite proportion, and the consumption of coke increases [2-4]. Therefore, the utilization of specularite has been limited. Composite Agglomeration Process (CAP) is an innovative technology invented by Central South University [5-7]. The process has the following merits: making reasonable utilization of different iron ore resources; improving the quality and output of sinters; manufacturing sinters with low basicity; significantly reducing energy consumption, etc[8-9]. It has been shown that large proportion specularite ores, as high as 40%~50% can be used well by CAP [10], but the mineralization of specularite pellet is still unknown during composite agglomeration processing. In this investigation, the induration characteristics of specularite ore pellets is studied by simulating CAP in laboratory, and the phase composition and microstructure of CAP product are also characterized by using microscope and Leica image analyzer (Germany, Leica DM RXp)."

Jan 1, 2011

By J. M. D. Wilson

An analytical program using a combination of SEM-based image analysis techniques is developed for automated modal analysis of ores containing silicate and other gangue minerals. Previous knowledge, gathered by means of either optical microscopy, X-ray diffraction, SEM, or electron microprobe analysis is used to establish discrimination criteria in the image analysis program. The program initially discriminates minerals on the basis of their relative grey values in a backscattered electron image. For those minerals which have overlapping grey levels the minerals are identified by the program using energy dispersive X-ray spectrometry with X-ray counting for twelve or more elements. This technique is useful to quantify ores in which the gangue minerals are numerous. Two cases of application are presented.

Jan 1, 1999

By Olga K. Karakasi, Angeliki Moutsatsou, Ioanna Kavallari

"The present study focuses on the amelioration of the behaviour of high calcium fly ash (HCFA), investigating its application in a new environmental field: oil spill clean up. High calcium fly ash is a by-product of electric power plants, produced annually in large quantities, whose greater amount is landfilled. Some of its properties, such as its chemical and mineralogical composition, its fine particle size, its porosity, floating ability and hydrophobic character make it an attractive material for this purpose. Researches showed that when added to an oil spill, it forms a semi-solid phase, which allows the quite total removal of the oil, but it is not stably retained on the surface. In order to ameliorate its floating ability, the decrease in its specific gravity by mixing with a lighter material is investigated. In the present study the mixing with two materials, already used in oil spill clean up, sawdust and a polymer, has been examined. Addition of 15-25% w/w sawdust to HCFA results in a material with better performance than HCFA or sawdust alone: it has a satisfactory floating ability and allows total removal of oil. Addition of the polymer, however, has resulted in no significant amelioration of the oil sorption behaviour of HCFA, probably because no affinity between HCFA and polymer has been achieved.IntroductionCoal fly ash is a by-product of coal combustion in electric power plants, produced worldwide in huge quantities, approximately 500 million tones annually. High calcium fly ash (HCFA) is classified to class C presenting a (Al2O3 + SiO2 + Fe2O3) > 50%. The production of lignite fly ash in Greece comes up to 13 million tones annually, of which only 12% is used in construction applications, the other being landfilled [5, 6].Besides its limited application worldwide as a construction material, research is focusing on the development of new environmental applications, such as waste stabilisation and solidification, soil and water environmental improvement [9, 12]. For the application of fly ash in further environmental fields several chemical modifications have been applied, in order to improve its properties. Extensive research has been focused on the conversion of both coal and lignite fly ash to zeolite and its further application in environmental field, such as the uptake of inorganic (heavy metals and ammonium [8, 11]) or even organic compounds (methylene blue [15]) from waste water streams, or the use as molecular sieves, to adsorb water molecules, SO2 and NH3 from gas streams, due to the high cation exchange capacity and porosity of the produced zeolithic material. Furthermore, lignite fly ash has been combined with sodium silicate solution, prepared by treatment of rice husk ash, and tetrapropylammonium bromide, to synthesise hydrophobic zeolite ZSM-5 [4]."

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 Hsi-keng Hu

"This paper deals with the flotability of stibnite and summarizes the major experiences and technological innovations of some typical practices of antimony sulfide ores in China. Experiences of cyanide-free and -less flotation of complex antimony sulfide ores and the application of the heavy media process to the preconcentration are described.Performance improvements obtained by innovations in operating techniques are also outlined and discussed. Technical innovations involve: (1) ramification roughing and differential-rate cleaning of stibnite-arsanopyrite ore; (2) the application of the new flotation reagent system; (3) process of separation flotation of Sb-Hg bulk concentrate; (4) extraction of gold from Au-Sb bulk concentrate; (5) flotation recovery of coarse stibnite particles.IntroductionChina is rich in natural resources of antimony and is one of the major antimony producers in the world. During the past several decades, a lot of research works have been done and many experiences in milling practices were gained, some of which are summarized briefly as follows.I. Heavy Media separation of Antimony sulfide Ore at Xikuangshan Hill, Hunan province (1)HMS as a technique of preconcentration of antimony ore has been performed more than ten years in China with good results.1. Ore characteristics The antimony ore of Xikuangshan belongs to the epithermal- metasomatic-filled doposit of antimony sulfide. Major minerals are stibnite (92.1%), antimony oxides (7.9%) and a small amount of pyrite and pyrrhotite; the gangue minerals are quartz, silicic limestone, calcite, hydrous kaolin, sericite, barite and others. The specific gravity of the ore is 2.8 and the specific gravity of stibnite and gangue are 4.6 and 2.654, respectively."

Jan 1, 1988

By Staia. Mariana H.

Thermochemical equilibria of the heterogeneous system Ti-N-H-CI-Fe-Cr-Mo-Ni-Mn-C were calculated by using a commercial software based on the minimization of the free energy. Equilibrium calculations were done for temperatures varying between 800" and l 100°C and an initial molar relationship between reactants, a=NJTiCI,, of 0.1 to 2. The deposition process was considered to occur at atmospheric pressure. The activities of the alloying elements of the stainless steel were considered equal to their molar fractions. It was shown that for the conditions studied the substrate is no inert with respect to the gaseous phase. The existence of liquid chlorides was predicted for temperatures between 800" and 850°C and a ratio between 0.3 and 0.9. The most important metallic chlorides which appears to be present from the calculations in appreciable quantities in the gaseous phase are iron dichloride and manganese dichloride. In the low-temperatures zone and for low initial nitrogen contents, it result that the appearance of the liquid chlorides seems that partially inhibits the production of gaseous HCI. The highest deposition process efficiency calculated is obtained at a temperature 2 900°C and a N2/TiCI, ratios 2 0.7.

Jan 1, 1995

By Wei-Tong Du, Yu Wang, Gang Wen

Carbon dioxide (CO2), a major component of the greenhouse gases, could be comprehensive utilized as a valuable resource to oxidize vanadium during the converter vanadium extraction process. The thermodynamic software, FactSage, was utilized to study the oxidation ability and theoretical cooling ability of using weak oxidant CO2 as coolant in vanadium-containing hot metal. Besides, experimental research on vanadium extraction in CO2 and O2 mixed blowing extracting process had been undertaken. The results indicated that the elements C, Si, V, Mn etc. could be oxidized by weak oxidant CO2, and the content of V2O3 in slag was approached to pure O2 blowing. Furthermore, CO2 had a remarkable cooling ability and the molten bath temperature kept on decreasing as CO2 blowing rate increases. This research has proved that CO2 and O2 mixed blowing in vanadium extraction process are effective.

Jan 1, 2015

By Naiyang Ma

"High oil concentration is one of the major barriers for recycling of mill scale of steel hot rolling mills. It is of vital importance to find cost-effective technologies of reducing oil concentration in mill scale in order to recycle the mill scale without causing detrimental effects on production and environment. This paper discusses in-process separation of mill scale from oil at steel hot rolling mills. Formation of mill scale and status of oily wastewater at hot rolling mills are reviewed in the first place. A mathematical model is then formulated to relate oil concentration in mill scale to physical properties of mill scale, chemical and physical properties of wastewater and interacting parameters between mill scale particles and wastewater. From this model, three approaches of in-process separation of mill scale from oil are derived: (1) avoiding contacts between mill scale particles and oily wastewater, and (2) maintaining low oil concentration in wastewater, and (3) collecting mill scale in upper streams of wastewater flows. In-process separation of mill scale from oil might have advantages of lower capital cost, lower operating cost and less additional environmental concerns, compared to other strategies of separating mill scale from oil.IntroductionHot rolling is an inevitable step in producing finished steel products. Figure 1 schematically shows a steel hot rolling process. Semi-finished steel products, slabs here, are reheated first, and then the reheated slabs are discharged from the furnaces and transported on hot rolling trains to descaling units for removing scale with pressurized water. After being descaled, the slabs are rolled by roughing mills. After treated with cropping and the second descaling, the slabs are finally rolled into finished products, coils here, by finishing mills."

Jan 1, 2012