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By R. Angulo

Carbon nanotubes (CNTs) have recently emerged as materials with outstanding properties. This has promoted their consideration as reinforcements for other material systems, such as ceramics. However, one of the fundamental problems with producing CNT-reinforced ceramics is the effective dispersion of CNTs during processing. This has been successfully carried out recently using organic solvents. This paper is a preliminery investigation into the rheological behavior of aqueous CNT-alumina slips, with the objective of moving towards a more environmentally friendly aqueous tape casting process for the production of CNT-ceramic composites.

Jan 1, 2008

By Chonghe Li, Xionggang Lu, Wei Xiao, Xingli Zou, Weizhong Ding

The reduction degree and rate of the initial ilmenite concentrate and pre-oxidation samples by hydrogen were investigated by using thermogravimetric analysis system. H2-TPR was used to detected reduction properties of the pre-oxidation products which were oxidized at different temperatures. The phase transformations and micromorphology changes during pre-oxidation and hydrogen reduction were identified by XRD and SEM. The FeTiO3 was decomposed into TiO2 and Fe2O3 at the temperature below 900 oC. With the temperature rising, Fe2TiO5 was the only stable phase in high temperatures. The reduction of pre-oxidation ilmenite concentrate was faster than the natural sample, which was attributed to the micropores generated on the surface of ilmenite concentrate during oxidation. The main phases of the reduction product were metallic iron, ferrous pseuodbrookite.

Jan 1, 2014

By Katsutoshi Inoue

Pectic acid gel crosslinked with epichlorohydrin was found to have very high selectivity to lead(II) and iron(III) ions over zinc(II) ion compared with commercial weakly cation exchange resins containing the same carboxylic functional groups, suitable for removing small amount of impurity metal ions from waste zinc plating solutions. In order to lower the cost, new adsorption gel was prepared from orange juice residue containing pectic acid by crosslinking with epichlorohydrin, which was also found to be suitable for removing these impurities. Further, very cheap adsorption gels was prepared not only from orange but also from apple juice residues by a simple method through just saponificating pectin substances contained in these residues into pectic acid by calcium hydroxide followed by water washing and drying. These adsorption gels exhibited excellent adsorption behaviors for removing the impurity metal ions away from zinc.

Jan 1, 2003

By Michael Altepeter

Big River Zinc Corporation, located in Sauget, Illinois, operates a neutral leach residue circuit. The residue produced in the circuit is sold to lead smelters for subsequent recovery of valuable metals. A research program was initiated several years ago to find a means of treating the residue at Big River Zinc to recover the valuable metals. The Ausmelt submerged lance reactor was selected as the best alternative for the first step of the process. Pilot scale tests were conducted at Ausmelt's facilities in Melbourne, Australia. Separations were excellent. 99%+ of the Zn, Pb, Cd, and Ag contained in the residue reported to the oxide fume. 99%+ of the SiO2,, Fe, Mg, and Ca in the residue reported to the slag which passed the EPA TCLP test. Subsequent leaching of the oxide fumes and purification of the leach solutions using conventional procedures produced solUtions suitable for zinc electrowinning and an upgraded lead sulfate cake for sale.

Jan 1, 1992

By David Seymour

Newmont Gold Company (NGC) located in Northeastern Nevada has been processing carbonaceous and sulfide refractory gold ores through a chlorination circuit prior to cyanidation. A "Flash Chlorination" pilot plant was installed in 1987 in an effort to obtain higher chlorine utilization efficiency and increase gold extraction. The Flash Chlorination process oxidizes organic carbon and sulfide sulfur. It also deactivates preg-robbing carbon, making the ore amenable to cyanidation. Significant recovery improvements were observed using this new process. This scheme has also been instrumental in the processing of higher than normal grade ores at economic chlorine levels. The Flash Chlorination pilot plant has been successfully treating carbonaceous ore on a production scale since April 1988. This paper summarizes laboratory and pilot plant optimization test work, using conventional and statistical methods.

Jan 1, 1989

By Lidong Teng, Seshadri Seetharaman, Aida Abbasalizadeh

0In the present paper, the feasibility of the recovery of dysprosium from spent Nd-Fe- B magnets containing approximately 9 wt% Dy was investigated by using molten salt process. The salt bath consisted of a mixture of NaCl-KCl-LiCl corresponding to the ternary eutectic composition. AlCl3 was used as a chlorinating agent in order to enable an efficient dissolution of metal in the molten salt phase in the salt bath. The metal chloride which is formed as the result of chemical reaction between the metal in magnet and AlCl3, is subsequently subjected to electrolysis in order to be deposited on the cathode. Graphite rods were dipped in the salt bath as electrodes and alumina crucibles were used as the containers for the electrolytic cells.

Jan 1, 2014

By Junfu Chen, Jiann-Yang Hwang, Yong Zhou, Lijun Lu, Likun Lia, Jixiong Liu

The sheet-like NiS-ZnS heterostructured composites were prepared by the microwave hydrothermal. The fabrication of the heterojunctions broadened the range of light response of ZnS. The photoexcited electrons of ZnS migrated to the redox potential of NiS/Ni2S under visible light irradiation, which can facilitate the effective separation of photogenerated electrons and holes in space. The visible photocatalytic activity towards hydrogen production for NiS/ZnS nanosheet heterostructed composites without co-catalyst achieved 0.28 mmol h–1, and the quantum efficiency was up to 18.6% under the wavelength with 420 nm visible light irradiation.

Jan 1, 2015

By Marcos Aurélio S. Costa, Nilton F. Nagem, Andreia B. Henriques, Herman S. Mansur, Alexandra A. P. Mansur, Antonio E. C. Peres, Valeria G. Silva

The superfine material generated in the Bayer process was used in one innovatively way as a precursor to geopolymerization techniques because of the presence of Gibbsite. Gibbsite can play a role in system adjustment because of the SiO2/Al2O3 ratio. Furthermore in the geopolymeric system it was studied the influenceof the additives such as kaolin, metakaolin and sodium trisilicate in an alkaline media. Others conditions to form the geopolymer were also evaluated such as solid/liquid ratio, SiO2/Al2O3 ratio and total alkaline. The raw materials and geopolymeric products were characterized by several techniques e.g. XRD, DSC, FTIR and SEM. Through the FTIR technique it was observed an increase in intensity and bandwidth in the region centered at 1010 cm-1, which is related to the asymmetric vibration Si(Al)-O, this is an indicating of the possible geopolymer formation This broadening of the band promotes a relative disappearance (overlapping) peaks at 965 and 935 cm-1 associated with raw material (ESPDust).

Jan 1, 2015

By P. C. Chaubal

The overall kinetics of oxidation of single partic1es of chalcopyrite have been studied for temperatures up to 1273 K. The experiments were conducted in a stationary bed reactor using a non-isothermal technique. Any mass and heat transfer effects on the kinetics of oxidation were eliminated by using a high-enough gas flowrate. Up to temperatures of 873 K, pore-bl1ocking kinetics were applicable, whereas above 873 K, power-law kinetics gave a satisfactory fit of the data. The activation energy was 215 kJ/mol below 754 Kand 23.7 kJ/mol above 1,060 K. Predominance area diagrams were constructed at various temperatures and used in conjunction with X-ray analyses of partially oxidized samples to determine the intermediate phases formed during the reaction. The analysi1s also provides a justification for the kinetic models used. The results indicate that the reaction rate is first order with respect to oxygen concentration and inversely proportional to the square of the particle size throughout the ranges of temperature studied.

Jan 1, 1985

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 S. P. Jupp

A 2-D coupled thermo-mechanical model was developed to simulate hot tandem rolling of AA5056 aluminum alloy using the commercial finite element software package, ABAQUS The model was used to predict the temperature, strain rate and strain distribution in the strip at any position in the roll bite and was verified through comparisons with literature results in terms of both temperature and strain predictions at the roll bite exit. A sensitivity analysis indicated that model predictions of temperature and strain at the roll bite exit were sensitive to the friction coefficient and moderately sensitive to the heat transfer coefficient for the conditions studied. Microstructure equations taken from the literature were used to make predictions at various positions in the strip. The temperature, strain rate and strain vary dramatically through the thickness of the strip in the roll bite. The sensitivity of the microstructure predictions to these parameters was assessed and it was found that using average values of temperature and strain rate in the roll bite versus exit values significantly influenced the resulting microstructure predictions.

Jan 1, 2001

By Klaus-Markus Peters, Robert M. Cravens, James G. Hemrick

"Degradation of refractories in molten aluminum applications leads to energy inefficiencies, both in terms of increased energy consumption during use as well as due to frequent and premature production shutdowns. Therefore, the ability to enhance and extend the performance of refractory systems will improve the energy efficiency through out the service life. TCON_ ceramic composite materials are being produced via a collaboration between Fireline TCON, Inc. and Rex Materials Group. These materials were found to be extremely resistant to erosion and corrosion by molten aluminum alloys during an evaluation funded by the U.S. Department of Energy and it was concluded that they positively impact the performance of refractory systems. These findings were subsequently verified by field tests. Data will be presented on how TCON shapes are used to significantly improve the thermal management of molten aluminum contact applications and extend the performance of such refractory systems.IntroductionThe production of molten aluminum creates aggressive environments for processing equipment, thereby requiring refractory materials to contain the aluminum during melting, transfer, treatment, and casting operations. Degradation of these refractories not only causes issues with reduced product quality and production yields, but also increases heat losses as the insulative properties of the refractories are compromised. Furthermore, in addition to disrupting production output, refractory failures lead to further impacts upon energy efficiency as large amounts of energy are lost during the cooling and subsequent reheating of the equipment as the refractory linings are repaired or replaced.The need for improved refractory materials is recognized throughout the industry. A joint U.S. Department of Energy and industrial workshop held in 2000 on applications for advanced ceramics in aluminum production [1] noted that refractory materials used in melt processing equipment have many limitations. The workshop report noted that these issues may be addressed by using advanced ceramics, but new materials must be cost effective when compared to current refractory materials. Also, in 2005 the Canadian aluminum industry produced a technology roadmap [2] having the goal of identifying and bridging gaps between current technological resources in the industry and future requirements. One of the areas identified as being crucial to the future of the industry was the need for improved molten aluminum-resistant materials."

Jan 1, 2009

By Varadarajan Seshadri

The performance of mould fluxes in satisfying its quality requirements can have a significant effect on the efficiency of the continuous casting process and on the surface quality of the products. This performance is affected by various parameters including the characteristics of the mould fluxes, the quality of the steel being cast and the operational conditions of the caster. The extremely complex relationships involving the parameters mentioned above make it very difficult to have simple criteria for selecting mould fluxes for casting a certain grade of steel in a continuous casting machine. These difficulties led steelmakers and mould flux suppliers to select mould fluxes based mainly on plant trials. In the present work, a software to help in the analysis and development of mould fluxes for continuous casting was developed_ This software includes several models for prediction of mould flux viscosity and consumption. A mathematical model was also used to predict the heat flux through the mould flux. The proposed methodology was applied to continuous casting of crack sensitive steels_ Some of the results given by this software are presented, discussed and compared to plant data.

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 Zhou Jiemin

In order to fully understand the behavior of the rectangular six- electrode electric smelting furnace and improve its design and operation, a three-dimensional mathematical model has been developed which incorporates the electrical and thermal flows into numerical solutions, assuming a steady state regime. The model has been used to simulate the performance of the 16500 kVA nickel matte smelter at Jinchuan in China, and various factors have been investigated. The results of computation are in agreement with the measured data obtained from this furnace and its physical model. Application of this model is described and the calculation on the Jinchuan smelter shows that the operation expenses can be reduced by optimizing the furnace geometry and some operating parameters.

Jan 1, 1991

By David M. Davidson

Seven intrusive phases have been mapped to date in the 1 b.y. Red Bluff Granite Complex (RBGC) near El Paso, Texas. This batholith is 20 km2 in area and intrudes older supracrustal units as well as a trachyte ignimbrite cap. Two early microgranite sills are spatially separated 6 km from a porphyritic, three-phase "ring complex" by a tin-bearing, biotite granite which cores the RBGC. These units are intruded, in turn, by a riebeckite granite which locally exhibits lineated and pegmatitic textures as well as exceptionally high light REE and Zr values (800 ppm La; 3,000 ppm Zr). The riebeckite granite is exposed in three separate occurrences within the Franklin Mountains. REE values in the RBGC are depleted in HREE and show distinct negative Eu anomalies. Typical La/Yb ratios are 5:1-2:1 with Eu values ranging from 10-80 ppm. The mineral source of the high REE values in the riebeckite granite has not yet been specifically identified, but is believed to be zircon.

Jan 1, 1988

By Baokuan Li, Fang Wang

"Comparing with the single electrode in electroslag remelting processes, two series-connected electrodes have the advantage of little inductance, lower power consumption and higher melting rate, which was widely used to produce superalloys and specialty steels. Detailed understanding of the electromagnetic field distribution is essential for both improving ingot quality and saving electric energy. In the present work, a 3D finite element model was developed for the magnetic field, electromagnetic force, current density and Joule heating field of electro slag remelting processes (electrode, slag and ingot) with two series-connected electrodes using Maxwell equation, Lorentz law and Joule law. The results show that the maximum current distribute occur at the middle of electrode, due to the interaction of selfinduced and mutual-induced of two series-connected electrode; associated magnetic flux density on the inner side of electrode increase and the outer decrease; The maximum joule heating is at the interface of slag and electrode. The parameter study shows that if the current frequency is greater than 35Hz, the current density in inner electrode tend to linear distribution; with the increasing of original current, The maximum current density near the wall in electrode will increase linearly; with the increasing of electrode innnersion depth and decrease of slag cap thickness and the maximum of the joule heat in slag will increase.IntroductionElectroslag remelting processes(ESR) are widely used to produce superalloys and specialty steels [l-3l_Two pair, four pair or six pair electrodes in electroslag remelting processes is common in casting large scale ingot, which has the advantage of little inductance, lower power consumption and higher melting rate, comparing to singe electrode. They have the same essence with two electrodes in ESR.Compared to the single electrode ofESR, the other electrode is added which can decrease the reactive resistance and power consumption in the two electrodes of ESR. It is a complicated metallurgy process with a series physical and chemistry phenomenon from the molten of steel to the solidification of ingot [4-71_ These physical and chemistry phenomenon originated the effect of alternating current of high intensity. The rule of the alternating current of high intensity which revealed the law of physical and chemistry phenomenon in ESR is the precondition of improving ingot quality and saving electric energy. Jihe Wei and Yongli Ren[S-9lstudied the distribution of electromagnetic field in single electrode ofESR with Maxwell equation and relative electromagnetic theory. It had the limitation that take the electrode and mold as infinite conductivity. A detail analysis of Electromagnetic fields in ESR had been conducted by Patel A D [JO-llJ using general stream-function formulation. It is difficult to extend to three dimensions which could not be used widely. Daniel V [lZJ and Kharicha A [BJ only analysis the current density associated magnetic flux density field and temperature field without the whole irlformation of electromagnetic field. Maopeng Geng [l4J considered the current density and temperature field of the real and fake electrodes in ESR without skin effect. As to the complication of the two electrodes of ESR, it is rarely reported the electromagnetic field and Joule heating field of the two electrodes in ESR. The rule of effect of electromagnetic and modification of numerical simulation should be studied in depth."

Jan 1, 2011

By Liyuan Chai

The corrosion mechanism of A3 steel induced by chloride ions in the purified water had been investigated with the A C Impedance technique. The results showed that there were another two factors which determined its electrochemical corrosive rate: the electrode potential and coverage ratio of chloride ions on the surface of A3 Steel. The corrosion mechanism of A3 steel in the solution with chloride ions emendation was two steps of electrode process with the rate-determining step of 0,32kFeClFeCle+--¾¾®++.

Jan 1, 2009

By Xiao-hui Fan, Xu-ling Chen, Xiao-xian Huang, Gui-ming Yang

Grate-kiln-cooler is a predominant process of producing iron ore pellets in China. Since this process is of multi-variant, strong coupling and large hysteresis characteristics, a reliable performance monitoring is thus essential to ensure product quality and economic benefits. Aiming to efficiently monitor the pellet induration within this process, this study proposed an approach that combines statistical analysis and quality soft-measurement. Soft-measurement of pellet quality was accomplished based on the predicted time-temperature profile, and the soft-measured indices were on-line monitored using statistical control charts. Based on the proposed approach, a monitoring system for grate-kiln-cooler thermal process was developed for a domestic pelletizing plant. Running results demonstrate that our system can assist in the detection or diagnosis of abnormal thermal state and finally helps to stabilize the pellet production.

Jan 1, 2016

By Petre Stelian Nita

In small steelmaking shops, in foundries and forging plants, there are not too many option to recycle the basic slags, which are not suitable for many purposes of recycling, because of their low chemical and structural stability. A solution of an adequate recycling is a direct recycling in EAF. Several quality requirements, physico-chemical properties and proportions of slags must be analysed. The progress in this fields permites to establish an adequate proportion of recycled slag, based on enough exact computation of the related property. For oxydizing slag, obtained during melting and in the first part of decarburization operation, the problem of phosphoms contents can be analysed using the phosphate capacity (C PO34-). For reducing periods, during deoxidization operation, desulphurization also occurs and the problem of the sulphur contents can be analysed using the sulphur and sulphide capacities ( Cs / Cs) Between this two complex thermodynamic indicators of the slags. a direct relation is established, using thermodynamic aspects, resulting from the equilibrium constants for dephosphorization and desulphurization process and also, using the optical basicity of slags, computable from the chemical analysis of the slags. On this basis starting from the steel quality requirements. adequate strategies can be established in order to obtain high rates of recycling (between 50-80%) of steelmaking slags. Important cost savings are obtained through this procedure, based on the correct amounts of the fresh lime, iron ore and fluidizers. Keywords: Slag, Properties, Recycling

Jan 1, 2003