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By Jian Li, Guo Chen, Bingguo Liu, Hongying Xia, Jinhui Peng, Libo Zhang

"Decomposition of ammonium tetramolybdate to prepare Mo03 using silicon carbide crucible in microwave fields was investigated. The results were analyzed Using TG-DTG and X-ray diffraction. Meanwhile, the effects of heating rat, material thickness, socking time, socking temperature on the structure of preparing Mo03 were studied. TG-DTG curves show that the decomposition process of ammonium tetramolybdate is only one stage, in the temperature range 300-350°C, whose begin to decompose when temperature increases beyond 300°C. The molybdenum trioxide was prepared by thermal decomposition. The quality ofMo03 was not affected under the heating rat is 12°C/min. It was beneficial for decomposition ratio with the lower material thickness, longer soaking time, and higher soaking temperature. XRD curves showed that it is viable method for preparation of Mo03 by decomposition from ammonium tetramolybdate in microwave fields.IntroductionMolybdenum is widely used in national defense, aviation, industrial and agricultural production as rare refractory metal. Molybdenum trioxide is vital raw materials for the process of preparation of molybdenum. The traditional production technology of molybdenum oxide is that ammonium tetramolybdate is calcined in rotary kiln or 4-tube furnace [J,2J. But the longer production time, the higher production cost, the lower furnace thermal efficiency, and bigger the energy consumption, especially the powder is easy to leak, the working environment is poor by using rotary kiln [ 3 l _ The particle of molybdenum oxide is non-uniform by using 4-tube furnace because of the uneven temperature of every tube and the poor exhaust of boat bottom [4l _ However microwave heating is quick and uniformity, it is a meaningful research that the microwave is used in the process of calcining ammonium tetramolybdate."

Jan 1, 2013

By N. Bazzanella

The hydrogen desorption kinetics of pure and Nb-doped magnesium hydride film samples was investigated by using a Sievert-type apparatus. The overall activation energy and the reaction order controlling desorption are (141±5) kJ mol-1H and n 4 for Mg hydride and (51±5) kJ mol-1H and n 1 for Nb-doped (5% at) Mg hydride indicating that, in the doped sample, hydrogen desorption is controlled by the H migration in transformed h-Mg layers. Structural analysis performed by X-Ray Diffraction (XRD) and Extended X-Ray Absorption Fine Structure spectroscopy (EXAFS) show that the catalytic effect of the Nb dopant is connected with the formation of NbH0.89 nanoclusters dispersed in the Mg hydride matrix. It is suggested that the catalysis process is also connected to the presence of Mg-Nb hydride interfaces where the transfer of H atoms preferentially occurs by connecting h-Mg grains and by the role of the MgH2-NbH0.89 interface as preferential site for the dissociation of the hydride phase.

Jan 1, 2006

By J. R. Donald

Surface and interfacial phenomena play a significant role in refractory performance. For example, the wettability of the refractory material with slag, matte, and metal influences infiltration and interfacial reactions. Yet, very little fundamental information regarding the surface properties of refractory materials and slag is available. Thus, in the present work, the sessile drop technique incorporating a high temperature furnace equipped with X-ray fluorescope was employed to investigate the surface and interfacial phenomena of fayalite-type slags on solid alumina at 1200?C. The iron to silica (Fe/SiO,) ratios employed were 1.4 and 2.0, and the oxygen potentials used were log p02 =-11 and log p02=-9 atmospheres. The contact angle between the fayalite-type slags and the alumina were determined to be relatively low, at about 16.9 to 19.6 degrees under the experimental conditions. The surface tension of fayalite slag (Fe/SiO2=1.4) at an oxygen potential of log -11 was 0.298, which agreed with the work of previous researchers. The surface tension of the fayalite was observed to increase with time. The spinel FeAl2O4. was determined to be the product of the interfacial reaction, and 8.8 to 15.8 mass percent alumina was dissolved into the slag after 40 minutes.

Jan 1, 1996

By T. Plikas, L. H. Gunnewiek, L. Oshinowo

"Electric furnace smelting is one of the principal unit operations for ferroalloy production, and increased process intensity, improved availability, minimal maintenance and a longer campaign life are common objectives for electric furnace operation in order to obtain favourable economics of production. Furnace designers have continued to develop innovative solutions, e.g., furnace cooling systems, that have allowed these objectives to be realised and CFD modelling plays a key role in the design process. Enhanced understanding of the energy transfer process in the furnace and the ability to develop, evaluate and optimize components of the crucible design to match process requirements are the key motivators for modelling.This paper provides an overview of recent applications of CFD to the design of electric furnaces. The aim is to illustrate what can be done, and identify areas where further work is needed in this field. Examples include furnace bath simulation, crucible cooling system design, taphole design, baking of Soderberg electrodes, off-gas systems, and fume control and building ventilation. It is argued that the trend is for numerical models to become more encompassing while at the same time more accessible, and therefore further improvements in furnace design will be realised with continued and well validated modelling efforts.IntroductionOne of the main processing steps in ferroalloy production is the smelting of ore in electric furnaces. The three-electrode, AC submerged arc furnace is most prevalent method for smelting in the industry, with shielded-arc and DC plasma arc furnaces achieving limited application (1,2). Commercial furnaces range in size from a few megawatts to more than eighty megawatts of supplied power, and operate with the objective of maximising the return on capital invested. Maximising productivity and energy efficiency are two pathways to achieving this objective, through process intensification, increased availability, minimal maintenance, and increased campaign life for the furnace and associated equipment. Concurrently, the need to reduce the environmental impact of metal production by controlling the emission of particulate emissions, greenhouse gases, and other harmful by-products must also be met."

Jan 1, 2004

By Stanko Nikolic

The Top Submerged Lance (TSL) technology, developed in the 1970s, is now widely used for the processing of a range of materials. TSL technology for continuous converting was first patented in the 1990s. The process is based on the use of calcium ferrite slag. Although this slag system had been applied elsewhere the phase equilibria had not been thoroughly investigated. This lead to a collaboration between the Process Technology group of Mount Isa Mines, now part of Glencore, and the Pyrometallurgy Innovation Centre (PYROSEARCH) at The University of Queensland. Through multiple research programs this complex system was successfully investigated. The results were then implemented within thermodynamic modelling tools. This combined new knowledge was then applied to the design and industrial implementation of the TSL continuous converting technology, ISACONVERT™. This paper describes the key findings of the research and how this was applied to the industrial implementation of the technology.

By Leonardo Mota, Felipe Perissé Duarte Lopes, Marcelo Gomes da Silva, Sergio Neves Monteiro, Helion Vargas

"Natural fibers, as a class of material, are attracting the interest of engineering sectors owing to specific advantages such as comparatively reduced cost and lower density as well as environmental benefits associated with renewability and biodegradability. For industrial applications, thermal properties, among others, are required. These are major requirements, especially in the case of an insulating natural fiber. In the present work, thermal properties of the curaua were investigated by photothermal techniques, i.e., the open photoacoustic cell and a method based upon the monitoring of the temperature evolution as a function of time. This investigation, in tum, permitted to evaluate two important thermal properties: the thermal diffusivity and the specific heat capacity of the curaua fibers. Indirectly, by means of simple mathematical relations, the thermal conductivity was also obtained. The results were compared with other materials and characterize the curaua fiber as an efficient insulator.IntroductionMaterials are gaining attention in recent years owing to their benefits for the environment as compared to synthetics. Being biodegradable, yearly renewable and recyclable, the natural planted-based are considered fully sustainable [1]. In particular, their life-cycle, from growing to industrial processing, absorbs as much C02 as it is emitted and makes them neutral with respect to greenhouse gases responsible for global warming [2]. Typical examples of these environmentfriendly materials are the lignocellulosic fibers that have been used in simple items such as ropes, baskets, textile, modest roofing, etc, since the beginning of our civilization [3]. In the past few decades, these natural fibers have been extensively investigated [ 4-1 O] as a possible reinforcement phase of polymer composites in substitution for synthetic fibers. In fact, engineering application of lignocellulosic composites are today in the market, especially in the automobile industry [11-13]. Out of the hundreds available natural fibers, only part of them exhibits superior properties to be qualified for composite reinforcement."

Jan 1, 2011

By Guo Xian Jian

In this paper, the gas composition calculations on the FeS-H20 system at elevated temperature were performed. The results show that the gas constituents are H20, S02, H2S, Sj, H2, and O2 and the order of the compositions partial pressure is PH2o> PH2 >PSO2 >PSj >PH2S >PO2 when FeS is oxidized into Fe304 and FeO by steam in the temperature of 700°C -960°C, the Claus process occurs with the decrease of gas temperature in the off-gas and the S02 and H2S in the gas are transformed into Sj , the critical temperature for the transformation is 600°C, and conversion percent of Sj is 97% at 330°C,

Jan 1, 1996

By Supachai Surapunt

The distribution behavior of V A minor elements (As, Sb and Bi) in the smelting stage of the Mitsubishi process were evaluated thermodynamically based on thermodynamic data and operating data. The fractional distributions between the gas, slag and matte phases considered as the degree of vapor saturation of 1.0 are as follows: 53.8, 27.2 and 19% for As, 23.6, 56.6 and 19.8% for Sb, and 91.3, 1.1 and 7.6% for Bi, respectively. Arsenic is mostly distributed to the gas and slag phases. It is effectively eliminated by volatilizing and slagging. Antimony is mainly in the slag phase, which is suitably removed by slagging. Bismuth is easily vaporized to gas phase. The degree of vapor saturation has a large effeet on the distribution behaviors of the three elements between the three phases. The amount of a minor element in the charge has an effect on the distribution of As but no effect on the distributions of Sb and Bi. Increasing matte grade and temperature results in the change of distributions for As and Sb, significantly. The change in the distribution ratio between slag and matte phases also considerably affects the distributions of As and Sb. The distribution behavior of Bi is not significantly changed by the change in matte grade, temperature and distribution ratio.

Jan 1, 2003

By N. L. Piret

Primary and secondary copper smelting dusts are being generated in varying quantities with very dissimilar characteristics due to the different compositions of feed materials and the type of process utilized. After categorizing the multitude of dust types, the criteria for on-site and off-site recycling of smelter dust in terms of type and concentrations of the accompanying elements are established. Thereby, consideration is given to the important aspects of: ? optimization of copper recovery ? quality of copper product ? valorization of accompanying elements ? elimination and disposal of deleterious impurities ? minimization of impact on operation ? effects on operating costs ? environmental impact of dust treatment on overall process Existing commercial, emerging and proposed copper smelting dusts, pyrometallurgical as well as hydrometallurgical, treatment schemes are reviewed and evaluated technically, economically and environmentally in an attempt to streamline the vast number of proposed options. Thereby, the high selectivity achievable in hydrometallurgical dust processing due to it being complementary to the smelting process is expected to be given increased consideration.

Jan 1, 1995

By Claassen J. O.

The Zinc Corporation of South Africa Ltd. (Zincor) operates an integrated roast ? leach ? electrowinning circuit. The efficient removal and control of iron forms an integral part of the process. Zincor developed its own iron removal process (Zincor Process), which was recently shown to be unique with some similarities to the para-goethite iron removal process. Newly developed operating parameters for iron removal are in the process of being implemented. These include a change in the pH-profile and operating temperature, the recycling of seed material and the utilisation of an alternative neutralising agent to aid iron removal. Some of these actions, together with the implementation of a pre-neutralisation step, new filtration equipment and control systems in Zincor?s Residue Treatment Plant have significantly reduced zinc losses associated with iron in calcine and the iron residue produced. This enabled Zincor to take a step closer to world-class zinc recovery levels of around 96% for a similar type of operation.

Jan 1, 2003

By Huimin Lu, Zhijiang Gao

Reduction reaction can happen among Al, V2O5 and TiO2 powders. Al can deoxidize metal V and Ti from the metal oxides. The electric igniter can be used to trigger the reduction. The reaction between Al and V2O5 is very intense and release large amounts of heat, but the heat which is needed to initiate the reaction between Al and TiO2 is not enough. These two reactions have been initiated first and V-Al and Ti-Al alloys can be obtained with a higher metal recovery percent. Through adjusting the ratio of Al, V2O5 and TiO2 powders, the system which combines these two reactions can ensured enough heat to react. KClO3 is added to the system, as the ignition agent, in order to make the reaction much complete. Finally, Ti-Al-V alloys can be obtained and need remelt to adjust the constituents.

Jan 1, 2016

By Wen Chen, Xinghua Liu, Zeyou Peng, Qiulin Wang

"Limonite is a collective for iron hydroxide argillaceous materials. It is very difficult to be treated due to the wide variation in specific gravity and magnetism and the high argillization rate in the course of grinding and beneficiation. The iron ore in Huangmei, Hubei, China is the typical representative of limonite. If the limonite is processed using conventional physical beneficiation methods (e.g. magnetic separation, gravity separation, flocculation-desliming-flotation, or a combined process of the three), it can only be obtained an iron concentrate grade of 51.98% and an iron metal recovery of 86.64%. However, the technique of flash magnetic roasting-magnetic separation can improve the concentrate grade to 61.03%, iron recovery to 91.17%. This paper describes the tests of recovering limonite by flash magnetic roasting in detail.IntroductionLimonite (mFe2O3, nH2O)[1] is a general designation for hydrous iron hydroxides and argillaceous matters. Limonite is hard to be separated because of its complicated geneses, comparatively weak magnetism, nonuniform grain size and being easily slimed during grinding. So most small and medium enterprises sell deslimed limonite product which was dealt with just by simple methods of washing, magnetic separation or gravity separation and so on. In recent years with the iron ore prices soaring, significant progress was made in mineral processing research of limonite. Laboratory research and industrial test results showed that flocculation-desliming-flotation process and roasting-magnetic separation process are the two best methods to recover limonite till now. To compare these two methods, roasting-magnetic separation process is superior to flocculation-desliming-flotation process in aspects of beneficiation indexes and industrial stability."

Jan 1, 2012

By Vinicius Alves Gomes, Jean Igor Margem, Thallis Cordeiro, Frederico Muylaert Margem, Roberto Faria Jr., Sergio Neves Monteiro, Marina Rangel Margem

Natural fibers are attracting the interest of engineering sectors owing to specific advantages such as lightweight and lower cost as well as for their inherent condition of being renewable, biodegradable, recyclable and neutral with respect to CO2 emission. In particular, the fiber extracted from the malva plant stem is nowadays recognized as one of the strongest lignocellulosic fibers. However, the thermal properties of the malva fibers have yet not been fully investigated. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity of a pressed malva fibers sample. The results revealed that these fibers showed a superior thermal insulation capacity.

Jan 1, 2015

By Karl-Heinz Daum

Outokumpu Lurgi Metallurgie GmbH, Oberursel, Germany ? give saleable by-products, ? not interfere with smelter performance, ? treat all gas streams simultaneously, and ? comply with environmental regulations. The latest developments in sulphuric acid plant design are presented.

Jan 1, 2002

By E. V. Redin, B. A. Dubrovsky, E. V. Knyazev, A. I. Starikov

"Ti-V magnetite is one of the most abundant composite ore resources in the world. This ore cannot be fully processed via blast furnace technology because of high content of Ti02. According to the investigations carried out in the USA and Japan ITmk3 RHF (Rotary Hearth Furnace) technology is a breakthrough in Ironmaking. Reduction, melting and slag removal can be achieved in just 10 min. The main objective of the investigation is to establish optimum operation conditions for the production of iron nuggets from Ti-V magnetite ore via the ITmk3 by means of the lab scale testing. Samples of ore from the Maly Kuybas deposit (Southern Ural), carbon reductant and fluxes were chemically analyzed. Green pellets were processed via a lab chamber furnace to simulate RHF conditions. The nuggets and slag were chemically analyzed. This preliminary test work provides valuable information which may be used for large-scale testing in a commercially sized RHF.IntroductionThe ITmk3 process upon which this paper focuses was developed by Kobe Steel in its research facilities [l]. After pilot testing at Kobe Steel's Kakogava Works in 1999-2004 the pilot demonstration plant was built and operations were successfully carried out by Mesabi Nugget joint venture in 2002-2004. Steel Dynamics put into operation the commercial plant at the Mesabi Nugget site in Hoyt Lakes (Minnesota) in 2010. Results were consistent with nugget characteristics confirming ITmk3' s flexibility with respect to raw material inputs. At the same time, no research in the field of nugget from the Ti-V magnetite bearing ore with high content of Ti02 and Alz03 has been done. It is well known, if a lot of Ti02 and Alz03 enter the blast furnace, slag becomes viscous. The viscous slag is obstacle for stable operation of the blast furnace. Besides, high content of Alz03 raises the melting temperature of gangue minerals disturbing the coalescence of reduced iron to the nuggets."

Jan 1, 2013

By Zhihe Dou, Yu Fang, Zimu Zhang, Yan Liu, Xiaoli Jiang Dianhua Zhang, Guanting Liu

"With the idea of “waste control by waste itself”, we come up with the crafts of using waste calcium carbide to mineralize CO2 in electrolytic aluminum waste gas, design and make out “Venturi gas-liquid-solid three stage reactor”, do experiments under the system of CO2-Ca(OH)2, investigate the influence on gas absorption by pH meter; investigate the influence on diameter distribution , rise velocity of bubble and local gas hold-up by dual conductivity probes; investigated the absorption of CO2 in every stage reactor under different initial proportion of CO2 by intelligent gas measurement system. The results showed that the reactor can fully absorb the CO2 in waste gas, and it has largely shorten the time of absorption and improve the CO2 utilization compared with the single stage reactor.The residual proportion of CO2 in the gas is below 0.08% through the absorption of three stage reactor,which show that absorption is extremely improved.IntroductionCarbide slag is a kind of polluting hydrolysis reaction byproducts in producing carbide in wet reactor, and it is mainly comprised by Ca(OH)2, It's estimated that there are about million tons carbide slag are piled up per year. Carbide slag is a kind of industrial wastes that hard to deal with ,which are treated by land filled in the past. It would not only occupy a lot of land, but also lead to secondary pollution [1].CO2 is the main greenhouse gas by now. In 2010, global CO2 emission has reached 33.5 billion tons, while China has now become the world's second largest emitter of CO2, emissions accounting for about one-seventh of the world [2].As the experts estimates, the greenhouse gas emission of whole nonferrous metal industry may over 0.6 billion tons per year, while CO2 emission of electrolytic aluminum is 0.334 billion tons per year [3]. So it is necessary and pressing to discover the reusing CO2 of electrolytic aluminum. With the idea of “waste control by waste itself”, we came up with the crafts of using carbide slag to mineralize the CO2 in electrolytic aluminum waste gas, which was experimented on the counterflow-three stage-venturi reactor,and studied the local gas holdup, residual concentration of CO2 and the volumetric transfer coefficient in the reactor."

Jan 1, 2014

By Daniel S. Gwinner

The tolling, or processing for a fixed fee, of aluminum drosses to recover the metal units is a common practice in the Aluminum Industry. The Dross Toller is acting for the owner, and since most dross processes result in material going to landfill, it is important for the owner of the dross to insure that the toiler is processing the material and handling waste disposal in an environmentally responsible manner. The paper discusses the Dross Toiler Audit Program, first from the Reynolds Metals Company perspective. Included are the reasons the company deems it necessary to audit and a description of the items covered during the audit. Finally, there will be a discussion of the audit from the Tollers perspective - what the Toiler can expect when the auditor arrives.

Jan 1, 1995

By Shengfan Zhou, XUEWEN WANG, Bianfang Chen, Mingyu Wang

Vanadium was leached from roasted stone coal by NaOH solution, and the effect of leaching temperature, leaching time, addition of NaOH, liquid to solid ratio, the grinding fineness of stone coal, and stirring speed on the vanadium leaching rate was studied. The kinetics analysis for the process is presented by the shrinking core model. The results show that the vanadium leaching ratio of roasted stone coal can be beyond 75% at the 6% NaOH addition, leaching temperature of 95°C, leaching time of 7h, liquid to solid ratio of 1.2mL/g, and grinding fineness of 0.111mm. The leaching process is controlled by interfacial reaction kinetics and the apparent activation energy was 59.36kJ/mol.

Jan 1, 2016

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from the University of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from theUniversity of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006