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By Peter G. Smith

Tri-calcium aluminate (TCA) is a dominant alkaline component of the red mud residue from the Bayer process. A method being considered for industrial implementation partially neutralizes the residue by contacting it with gaseous CO2. This paper outlines the chemistry of CO2neutralisation of TCA under conditions relevant to the treatment of Bayer residue. CO2 neutralisation of the liquor is fast. It results in the formation of amorphous aluminium hydroxide and dawsonite that agglomerate together. Neutralisation of solid TCA is slower and leads to the formation of calcite, dawsonite and amorphous aluminium hydroxide. The dissolution of TCA in partially neutralised slurries causes pH reversion. However the carbonated solutions contain a store of bicarbonate that can supply aqueous carbon dioxide to complete the transformation. The pH at which the carbonation is carried out will affect the degree of TCA transformation during the carbonation process. In particular, if the pH of the carbonation is too low (near 7.0), calcite precipitation is inhibited and the degree of transformation is low. Controlling the carbonation pH helps to optimise the neutralisation process.

Jan 1, 2003

By F. A. Fasoyinu

The mechanical properties of yellow brass (C85800), high strength yellow brass (C86300), and high manganese brasses (C99700 and C99750) cast in permanent molds have been studied. The tensile properties as well as fracture and impact toughness of these alloys are strongly dependent on the chemical composition. Alloys and/or compositions exhibiting relatively high zinc equivalent often exhibited high ultimate tensile strength and yield strength with significant reduction in ductility (% elongation). In order to achieve optimum properties with a good balance between strength and ductility, a calculation of the zinc equivalent before alloy preparation can be useful.

Jan 1, 1999

By Zhong Juya, Wang Yong, Guo Xueyi, Song Yu, Tian qinghua

"In this work, the flow of zinc in China, 2004, was traced within the STAF model, and the situation of production, consumption and recycling of zinc resources in China were introduced. The SFA is performed on zinc flows during its one year life cycle in detail. The result reveals that China produces and utilizes a large amount of zinc, while the efficiency of renewable zinc resources is still relatively lower. As one of the biggest producer and consumer of zinc in the world, China is facing a severe depletion of zinc resources. How to increase the resource efficiency is a significant issue for zinc industry of China. Based on the result, several advices were proposed in the paper, aiming to contribute important reference information for the industrial metabolism and resource management and recycling of zinc industry in China. IntroductionZinc is one of the important metals in national economic development in China; it has good conductivity and corrosion resistance, with high scalability when heated to 100 ~105_. Zinc is mainly used for galvanized zinc industry, as the coating of steel and various parts, and it has also been applied to the manufacture of brass, bronze and corrosion-resistant alloys, which are widely used in machinery manufacturing, printing, national defense and so on. In addition, zinc compounds are utilized in various fields, for example, ZnO is used for infiltration wood, paper, rubber, paints, etc.; ZnSO4 for leather, ceramics, textiles, medicine, etc.; ZnCl2 for infiltration wood; ZnS2O4 and Zn (HSO2 • CH2O) 2 for the paper and textile bleaching, etc. [1]. The extensive use and consumption of zinc in industrial production and social life promot the rapid development of zinc industry, which made zinc the third largest non-ferrous metals in the world."

Jan 1, 2008

By R. Parada

In January 1995, Disputada Mining Company Ltd. (Compañia Minera Disputada de Las Condes) started up the Expansion Project for the Chagres Smelter, following an investment of US$M 2 15. The new smelter replaced the 44,000 tomes per year revervatory furnace with an Outokumpu Flash Smelting Furnace (FSF) designed to produce 118,000 tonnes per year of copper. Nowadays, this smelting unit has achieved a 40% over design performance. The landmarks of this modernization project are described. The start up period in 1995-1996 was characterized by the impacts of several restrictions that prevented the smelter from reach design production. The design performance was reached in 1997-1998 through the implementation of solutions designed to eliminate, or at least mitigate, the restrictions found early on. The smelter has been further optimized in the 1999-2000 period, leading to a new record anode copper production rate of 148,000 tonnes in 2000 while obtaining 98% approval for our different anode shapes. The objective of this paper is to discuss the consecutive processes of start-up, achievement of design capacity, and operational improvements to go well beyond the design capacity. These processes took place between early 1995 and late 2000, under the principles of Continuous Improvement that promotes the effective participation of the workers in the technology innovation and Enterprise Management.

Jan 1, 2002

By James Wang

In July 2003, The Office of Hydrogen, Fuel Cells and Infrastructure Technologies of the Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy solicited Grand Challenge Proposals to establish three Centers of Excellence in hydrogen storage developments for reversible metal hydrides, non-reversible chemical hydrides and carbon storage materials, respectively. The program mission is to research and develop cost-effective, on-board hydrogen storage systems that enable a minimum range of 300 miles within the weight and volume constraints of the vehicle. Currently, no hydrogen storage technology available can meet the DOE cost and performance targets. In April 2004, Sandia National Laboratories was selected by DOE to lead the Metal Hydride Center of Excellence with partners from 5 other national laboratories. We will present the organization and recent accomplishments of the Metal Hydride Center which is confident to accomplish DOE/FreedomCAR and Fuels Partnership objectives for 2010 in hydrogen storage for vehicular transportation applications.

Jan 1, 2006

By A. F. Sidorov

A method of improving mineral recoveries from ores by modifying the physical and chemical properties of minerals using radioisotope radiation was tested. It was observed that irradiation modifies mineral cell sizes, changes the crystal structure of some minerals, reduces the sulfur content 1 to 1.5 % in sulfides, changes the zeta potential, alters the surface properties of mineral grains I and produces other changes. Preliminary tests indicate that accelerated electron treatment of ores in connection with mineral processing has a potential for improving mineral recoveries by flotation and by magnetic separations.

Jan 1, 1989

By Tatsuki Uzawa, Takashi Nagai

The consumption of Nd and Dy is increasing dramatically because of an exceptionally high demand for Nd-Fe-B-(Dy) magnets and a significant amount of the magnets are wasted. It is important to develop a recycle process the elements from the wasted magnets. In this study, Nd and Dy were extracted from the magnets by silver at high temperature. Nd can be extracted more than 70 % by silver. However, Dy is extracted only 25 % in the same experimental condition.

Jan 1, 2014

By Min Chen

A numerical simulation of the stress field of the solidified shell in the mold during continuous casting of peritectic steel slab was calculated with commercial software. The results showed that the maximal stress on wide face of the solidified shell was located at the corner and near middle of the slab, and it increased with increasing the width of slab. In addition, the stress was also influenced by operating parameters such as superheat degree, drawing speed and cooling intensity of the mold, and the maximal stress value and its position changed with these parameters. For the slab with section size of 3200mm×150mm, the proper drawing speed was around 1.2m/min, with cooling intensity of 5500L/min while the superheat degree was 15°C to 25°C in order to prevent longitudinal crack occurring during peritectic steel continuous casting.

Jan 1, 2009

By XUEWEN WANG, Xingming Wang, Xuehui Liu, Mingyu Wang

The Panzhihua titanium concentrate contains high contents impurity of Mg and Al, and it is difficult to prepare high grade titanium slag. To solve this problem, a sodium salt roasting-acid leaching process was proposed for removing the impurities in titanium concentrate. Na2CO3 and titanium concentrate were mixed with the proportion of 1:4, and then the mixture was roasted at 700 for 2h. After roasting, the calcine was leached with HCl solution. The experimental results showed that the removal rate of silicon and aluminum can reach more than 85% and 80%, respectively, at leaching temperature of 70 , leaching time of 4h, HCl addition of 5ml and liquid-solid ratio of 4:1.

Jan 1, 2016

By Zhuoqing An, Qi Li, Zhancheng Guo, Yanling Zhang

Fluidized bed is an important iron-making reactor, especially for the finely sized iron-bearing materials. However, defluidization caused by sticking between particles extremely limited its wide spread commercialization. In this paper, apparent viscosity was put forward to express the ability of particles to resist movement, which is reasonably considered as the comprehensive results of interaction between particles. Meanwhile, an experimental measuring method of apparent viscosity of particles was proposed, during which the torque exerted on the rotating blade in a particle layer is measured, and then the apparent viscosity is obtained based on the motion equations of powder particles. Further, the apparent viscosity of iron particles was measured by using of this method, and the effects of shape, size, and temperature were examined. The data can provide important information for understanding when and why defluidization happened.

Jan 1, 2015

By Chao Zhang, Jian Guo, Chaoquan Yao, Leige Xia, Xinyu Li, Jianliang Zhang

In this research, analytical reagents were used for the sintering experiments. And the sinters were using X-ray diffraction, scanning electron microscope and mineralogical microscope analysis to study the effect mechanism of manganese on the silico-ferrite of calcium and aluminum (SFCA) bonding phase formation during the sintering process. The results indicated that the increasing content of manganese would greatly reduce the content of SFCA, and promote the formation of calcium aluminum silicate and the amount of pores and cracks. The existence of manganese inhibited the silicon form into the SFCA and a great deal of Fe2O3 was participated in the crystal transition to Fe3O4. When the ratio of the added manganese was less than 3% in the mixing, the calcium ferrite was in substantially interleaving corrosion with hematite and magnetite. Both the porosity and silicate glass phase content were low simultaneously, which contributed to the sintering production.

Jan 1, 2015

By Yong Hack Lee

Nonferrous smelting processes have been through a rapid transformation since the beginning of 1980. The copper smelting technology has changed from the conventional Blast Furnace process to the Flash Smelting and MIB process. In the field of lead smelting, the technology has changed from the Blast Furnace Smelting to the Direct Smelting such as QSL and KIVCET. In 1992, Onsan Refinery successfully commissioned Direct Smelting QSL technology for lead. The QSL could produce more than 160,000 ton per year of lead bullion from lead concentrate and various residues. Moreover, since the year 2000, the TSL (Top Submerged Lance) Technology utilizing the same Direct Smelting process has been successfully commissioned to treat lead concentrate as well as lead sulfate residue produced from a hydrometallurgical zinc plant. This paper presents and compares the energy flows of lead smelting processes such as a conventional process and the Direct Smelting Processes plotted on the Pb-O-S phase diagram. The oxygen potential diagram suggests how to control the oxygen potential in the furnace. Also, it describes the recent operational experience in the TSL plant of Onsan Refinery with necessary mass balance of key elements.

Jan 1, 2003

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 Congcong Yang, Jian Pan, Deqing Zhu, Yang Zhong

A study of pelletization of one imported chromite concentrate with coarse site, poor ballability and refractory roasting performance was conducted in small scale tests, and high pressure grinding rollers (HPGR) was used to improve the pelletization. The mechanism of HPGR was revealed by means of SEM images and optical microscopy. Compared with the ball milling pretreatment, HPGR pretreatment can not only enhance the ballability of pellet feed but also drop the roasting temperature. Fired pellets, containing proper chemical compositions with high compressive strength of 2917N/pellet and good metallurgical performances, have been manufactured. The mechanism of HPGR reveals that chromite particle surface turns to more irregular after HPGR treatment and more new surface being formed because of more cracks, sharp corners and edges appearing, resulting in higher surface chemical activity, all of which improve the ballability of the chromite concentrate and contribute to the consolidation of fired pellets.

Jan 1, 2015

By Claude Lorenson

"The Spyrometer™ imaging pyrometer brings new dimension of imaging capabilities to temperature measurement technology by combining a high temperature video camera with scanning optical pyrometry. This gives the operators the ability to observe process conditions while measuring the temperature of virtually any object or region in the field of view. Since the lens tube of the camera can be air or water cooled, it is possible to see inside furnaces giving a very good view of many different types of metallurgical processes. Specific benefits in process knowledge and maintenance tasks for furnaces in different types of metal industries are discussed.1-Principles of Imaging PyrometryLens tube, camera and processorImaging pyrometry is the combination of video imaging and computer-driven pyrometry that measures the temperature of certain zones (selected by the operator) within the image viewed on the monitor screen. To obtain a detailed image of the metallurgical process under observance, it is necessary to place the optical objective of the camera close to the process. The Spyrometer™ (which is Quadtek's tradename for its imaging pyrometer) objective is housed in a lens tube that is cooled and permits insertion inside the vessel of interest. The length of the lens tube is chosen on the basis of making sure that the tip of the tube is just beyond the refractories lining the inside of the furnace. In most pyrometallurgical processes, we have found that the most reliable system set-up uses a water cooled shroud to cool the lens tube optics. A sapphire window provides maximum protection from the environment. Even in the case of the water cooled version, there is an air purge for the lens that keeps the objective clean and protects against hot metal splashes."

Jan 1, 1997

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 Qian Li, Haiyan Leng, Kuo-Chih Chou, Haoyuan Xiao, Zhigang Yu

Magnesium borohydride and Magnesium alanate were synthesized by mechanochemical metathesis reaction. The thermal decomposition behaviors of Mg(BH4)2-nMg(AlH4)2(n=0.5,1) systems were investigated as potential hydrogen storage materials. The results showed that the systems started to desorb H2 at 120 ℃ and desorbed 3.9 wt. and 4.9 wt.% H2 below 300 ℃ when n equals 0.5 and 1, respectively, while individual Mg(BH4)2 started to desorb H2 at 250 ℃ and desorbed only 0.82 wt.% H2. Because of the exist of the Mg(AlH4)2, the isothermal desorption kinetics of Mg(BH4)2 in the Mg(BH4)2-0.5Mg(AlH4)2 systems was 50% faster than that of pristine Mg(BH4)2. In addition, the re-hydrogenation rates also increased 49.4% and 37.9%.

Jan 1, 2015

By G. Gerbeth, Y. Gelfgat, A. Cramer, A. Bojarevics

The production of highly porous metallic substrates requires an effective and well controlled production of metallic fibres with diameters in the range of 50 to 200 microns. The melt extraction, where a quickly rotating wheel extracts fibres directly out of the inductively heated melt, is a promising technology for that purpose. The main limitations of this process are due to turbulence within the melt and a wavy motion on the surface. Both effects give rise to strong and time dependent deformation of the melt surface which, in turn, causes non-stationary conditions of the contact zone between the extraction wheel and the melt. In the patent literature many examples can be found which try to overcome these problems by submersing mechanical parts directly into, or placing them at least in close vicinity to the melt, aiming at a stabilisation of that contact region. Even made of heat resistant ceramics they suffer from corrosion or cracks and do not work reliable at all. The present work describes a non invasive control mechanism by means of a magnetic field. Model experiments were carried out to study the calm down of the turbulent surface of a inductively stirred melt. The stabilisation of the melt surface has been demonstrated in practise by the installation of a solenoid at a working extraction facility under rough industrial conditions like a powerful induction heating and vacuum.

Jan 1, 1999

By Lu Lin, Yan-ping Bao, Min Wang

In order to forecast the cost of dephosphorization during BOF process, and achieve economical dephosphorization of BOF. The mathematical model of dephosphorization cost for BOF process was established. The model calculations show that, when the silicon content and phosphorus content are increased in hot metal, and the final phosphorus content of BOF is decreased, the dephosphorization cost will be increased. The silicon content of hot metal is increased of 0.1% in the plant, the dephosphorization cost is added by 9 RMB/ton steel. The De-P cost of mode A is much higher than the other two modes for three typical production modes of single slag melting process, when the phosphorus content of hot metal is higher than 0.14%, an increase in the phosphorus content by 0.01%, the De-P cost of mode A is added by about 7 RMB/ton steel. Meanwhile, when the phosphorus content of hot metal is lower than 0.165%, the De-P cost of mode C is higher than mode B’s. For BOF single slag melting process, the dephosphorization cost calculated by model is between ± 2%, proving that the model is reliable for the prediction of dephosphorization cost.

Jan 1, 2015

By E. Munnik

The Chambishi Metals Cobalt Plant in Zambia has recently installed a novel oxidation/precipitation pressure leach process as part of the COSAC (Cobalt from Slag and Copper as by-product) Project. An iron-cobalt-copper alloy, produced by the carbothermic reduction of slag, is atomized and pumped to the COSAC Leach Plant, where cobalt and copper are recovered as dissolved sulphate salts, and iron is rejected primarily as hematite. Cobalt and copper are subsequently recovered as cathode metal in the existing Chambishi operation by conventional electrowinning. This paper examines the challenges faced during the design and subsequent successful commissioning of the COSAC Leach Plant.

Jan 1, 2003