Search Documents

By J. Etay, S. Daugan, Y. Fautrelle

"New type of electromagnetic parametric instabilities arising at the free surface of liquid metal in the presence of a low frequency magnetic field are presented. First, the mechanism of the instability is analysed in an idealised case. Then, the experimental device working with mercury is described. Various shapes, both regular and irregular, of free surface are found. A experimental stability diagram is obtained. Measurements of the deformation performed on photographs are compared with physical orders of magnitude.IntroductionWhen a liquid metal pool of electroconductivity a is submitted to an A.C. magnetic field B = B0 cos mt, electrical currents j are induced in the liquid metal and interact with the applied magnetic field to create electromagnetic body forces F = j x B. Those Lorentz forces comprise both a mean value (time average) and an oscillating part. Those forces are widely used in many metallurgical processes to stirr a liquid metal or to control its free surface, e. g., in aluminium continuous casting or electromagnetic levitation problems (1-3). When liquid metal free surfaces are submitted to AC. magnetic fields, the shape of those interfaces may interact with the applied field and leads to a various instabilities. A review of these instabilities may be found in Fautrelle (4). That instabilities may be a problem for the control of processing as electromagnetic levitation or quasi-levitation."

Jan 1, 1999

By Jose Bengoa

Low metal prices and environmental restrictions are always a challenge for copper smelters operation and its productivity. Thus, in order to reduce production costs and control gas emissions, improvements of the Teniente Converter (CT) operation were made at 110 Smelter Plant of Southern Peru Copper Co" 110, Peru, and the main objective was to increase its capacity for smelting copper concentrates without affecting normal operation, The present work eorresponds to a recent study conducted during the normal industrial operation of the Teniente Converter in this plant and, it shows the effect of increasing air oxygen enrichment from 28 to 34% on its productivity. The results show an increasing of concentrate smelting rate from 800 to 1370 tpd and hence a notorious improving in copper production, and practically no effect on the refractory consumption. The increment of the concentrate throughput, increases also the SO2 concentration and the sulfuric acid production, showing the effort done by this operation in order to accomplish the environmental Peruvian regulation,

Jan 1, 2003

By Qingyu Deng, Shiwei Ma, Guibao Qiu, Hua Wang

"The flow behavior of the blast furnace slag bearing titanium, like viscosity, play an importance role during the iron-making process with the vanadium-titanium magnetite, which is a very special minerals in Panzhihua, China. The dependency of the viscosity on the chemical composition like TiO2, Al2O3, MgO, binary basicity (CaO/SiO2), temperature, reaction time were studied. The experiments showed that the viscosity decreased with the increase of TiO2, MgO content and binary basicity, and it increased with the increase of Al2O3 content and temperature. The viscosity showed a slight decrease within 60mins’ reaction with graphite crucible, however, it increased rapidly afterwards with the formation of Ti(C, N).IntroductionThe ordinary iron ore has been an essential part of raw materials for vanadium-titanium magnetite smelting in Panzhihua to avoid a series of problems, such as slag thickening, adhesive bond of slag and hot metal, etc. The ratio of vanadium-titanium magnetite has been decreased gradually since 1970s, and has down to about 65% now. However, with the substantial appreciation of price of imported ordinary iron ore, Panzhihua Iron and Steel Group aims to increase the ratio of vanadium-titanium magnetite and decrease the dependence on ordinary iron ore in order to lower the cost of smelting process."

Jan 1, 2012

By Ning Wang, Bing Xie, Hong-Yi Li

"Compared to traditional sodium roasting, calcified roast inhibits chlorine pollution. A vanadium extraction technique based on a calcified roast is especially suitable for vanadium slag with high calcium content. In this report, V205was extracted from vanadium slag by calcified roast followed by acid leaching and hydrolysis precipitation. In optimized conditions, the high silicon low vanadium slag was roasted at 850'C for 2 hours without CaO addition. The roasted materials were leached with 35 % H2SO4 in liquid/solid ratio of 5:1 (mL/g) at 95OC for 4 hours. The extraction of vanadium was as high as 97.66 %. These results are instructive to V2O5 production in industry.IntroductionVanadium slag is produced in converter, sodium salt roasting is the commonly used technique to extract vanadium. In sodium salt roasting, vanadium slag is roasted with sodium salts including sodium chloride and soda as additives, followed by leaching with acidic or basic solution [1]. However, in this process chloride reacts to produce corrosive gases including HC1 andCl2- SO2 and SO3 can also corrode equipment severely and are also an environmental contaminant. The low melting point of sodium salts leads to fusion agglomeration, which blocks vanadium oxidation and thus decreases the extraction rate of vanadium. A large amount of sodium salts consumed as roasting additives increases the production cost. Moreover, sodium salt roasting requires low CaO content in vanadium slag. When the CaO content increases to 1%, V2O5 extraction can amount to 4.7%-9% [2]. For vanadium slag with high CaO content, the sodium salt roasting technique leads to low vanadium extraction rate."

Jan 1, 2012

By Ting Liu, Qian Li, Peng Deng

The wastewater containing Hg2+ and Pb2+ does great harm to the environment and human bodies. Traditional wastewater treatment cannot fundamentally put a stop to heavy metals pollution for producing secondary pollution. In this paper, Hg2+ and Pb2+ in wastewater were removed and recovered by sulfide precipitation- flotation. Sodium sulfide was used as precipitant and butyl ammonium aerofloat was used as collector. Results indicated that Hg2+ and Pb2+ could be reduce to less than 0.03mg/L and 0.16mg/L respectively by both coprecipitation- floatation and fractional precipitation- floatation. In these two methods, fractional precipitation flotation could not only remove Hg2+ and Pb2+ from wastewater, but also could recover mercury and lead effectively. The infrared spectrograms showed that the adsorption between butyl ammonium aerofloat and mercury precipitate or lead precipitate is chemisorption.

Jan 1, 2015

By S. Suzuki, Y. Maeda, N. Wakamatsu

"A new pyrometallugical technology, named KLS process, has been developed by Dowa Mining at its Kosaka Smelter to smelt various kinds of lead raw materials.The process consists of clearly separated two reaction steps, smelting and reduction. For this purpose, respective stationary furnaces are installed which are connected by a slag launder.Dry raw materials, together with pulverized coal and oxygen-enriched air, are injected through a lance pipe into the molten slag in the first furnace. It is kept under a high oxygen potential to remove sulfur completely. Resultant PbO rich slag overflows to the second furnace where pulverized coal and insufficient air are also injected through a lance pipe to reduce PbO to lead bullion and to compensate for thermal deficit. The entire operation is carried out continuously. The process development started back in 1981. In late 1986, a pilot plant with a capacity of 3.5t/H was constructed.Already nearly 20,000 tons of raw materials, mostly lead sulfate mixtures have been smelted successfully.IntroductionFor a long time, main raw materials for lead smelting at Kosaka smelter have been such secondary incombustibles as lead sulfate and lead-barium sulfate. The former is leach residue of the copper smelter flue dust and the latter originates from Iijima zinc refinery. While the most of lead concentrates produced locally has been smelted by an ISF of Hachinohe smelter in which Dowa Mining has a share.The surplus lead concentrates were processed at Kosaka by a hydrometallurgical method to convert PbS to PbSO 4 as pretreatment, and followed by simultaneous smelting together with the above secondary materials (1). Approximate output has been 1,5000 /M of lead bullion and slightly more than 2,000t/M of refined lead by adding lead bullion returned back from Hachinohe smelter (2)."

Jan 1, 1988

By Mingmei Zhu, Lang Hu, Yu Wang, Hongpo Wang, Congjing Zhang

Magnetic field has a great effect on the crystallization behavior of mold flux and properties of the flux film between mold and strand, on which the surface quality of strand was deeply depended in continuous casting process. Therefore, studying the change law of the crystallization properties of mold flux in magnetic field is of great significant. In the present work, based on intensity of the applied magnetic field with the range from 0mT to 60mT, the crystallization ratio, crystal size and mineralogical phases of the flux film were discussed. The results show that crystallization ratio increases with the increasing magnetic field intensity, and the crystal size becomes bigger at the same time. The magnetic field promotes the crystallization ratio and growth speed of the crystallized grains of mold flux. However, magnetic field doesn’t change types of the mineralogical phases.

Jan 1, 2015

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 J. M. Skeaff

As much as 100% of the gold and 67% of the silver in a sulphur-bearing hydrometallurgical leach residue have been transferred to copper metal at copper smelting temperatures by dissolving the partially calcined residue in an iron-bearing slag maintained in equilibrium with the liquid copper metal and matte phases. The precious metals can then be recovered by conventional refining techniques. Copper can be recycled at least four times without any detrimental effects on gold and silver transfers and recoveries. Apparent copper recovery in the .process can be over 100% because of the copper content of the residue. Based on slag analys.es, the overal1 recovery of gold in the copper metal and matte phases varies from 94% to 100% under all conditions investigated. On the? same basis, silver recovery varies .from 9S% ?to 99% under optimum conditions, but is only 4S% to 73% under other, less attractive conditions. Unaccounted for silver losses of' about 30% make it difficult to determine the major factors affecting ?silver transfer and recovery. A method for implementing the technology on a commercial scale at a Canadian copper/zinc smelter has been proposed. A preliminary economic assessment and comparison of the proposed pyrometallurgical process with conventional cyanidation indicates that either process is economically attractive for recovering gold and silver from leach residues. Although the capital costs are higher, the pyrometallurgical process is simpler, has higher recoveries, lower operating costs and no .potential environmental problems related to cyanide disposal.

Jan 1, 1989

By Junbiao Liu

Rutile is mostly produced from placer sands. Its beneficiation from primary deposits has rarely been investigated. However, there is interest in primary deposit because of the depletion of sand deposits. The Zaoyang deposit in China is the only rutile primary deposit currently mined. The plant employs a Tabling-Magnetic process which recovers only 20% Ti02 at a grade of 87%. This study shows that significant improvement on the recovery (52% at the same grade) can be achieved. This study includes a detailed mineralogical examination and the development of a processing flowsheet of the ore. The gangues are primarily amphiboles, garnets, zoisites, and chlorites. The liberation of rutile occurs at about 200 mesh. Gravitational, flotation, and magnetic separations are all employed in the process developed, depending on the mineral characteristics and experimental results. The flotations circuit utilizes benzyl arsonic acid to float rutile and sodium fluosilicate to depress the gangues. This is a new reagent scheme for rutile flotation.

Jan 1, 1989

By Benoit DeBecker

Laboratory-scale experiments have shown that chromium metal could be recovered from chromate wastes by modifying slightly the chromium electrowinning flow-sheet. After reduction by sulhr dioxide and precipitation of chromic hydroxide, the solid residue is dissolved in the chrome alum solution and the metallic impurities are removed by cementation on manganese. The presence of dissolved manganese in the electrolyte does not affect the cathodic deposition of chromium and it eliminates the anodic production of Cr(V1).

Jan 1, 1994

By Wang Jia, Chai Li-yuan, Zhang Jin-Long, Peng Bing, Zhang Qiang

"Electrolytic manganese dioxide (EMD) residue was mixed with shale and fly ash as the main materials to make solidification/sintering brick for the utilization of the residue from EMD production. The effects of sintering temperature, sintering time, solid waste content and cooling process on its mechanical properties and toxic elements solidification were investigated according to compressive strength and leaching toxicity. The results showed that the calcined residue had capability of solidifying toxic metals and exhibited perfect strength after treated in the optimal parameters of EMD residue below 50%, temperature at 1000-1100°C, time3-5h, and semi-quenched at 600°C1 InstructionSolid clay-brick holds the leading position among building materials for a very long time in China. The traditional technique of making clay-brick has the drawbacks of backward process, simple facilities and single product. Since Chinese Reform and Opening-up, urban-rural construction and real estate have been booming with the rapidly development of national economy and science technology. The problems of ruining fertile land, environment contamination and high energy consumption in the traditional technique of clay-brick making have not been solved yet. On the other hand, more than 7 billion tons of industrial wastes are accumulated over years which occupies over 6.7 million hectares filed and causes serious environmental problems[1-31. Strategy present in ""The Chinese Agenda of the 21st Century"" required the production of wall materials less energy conservation, land saving and waste recycling.Coal gangue[4-9l, fly ash[I0- 13l, sludge from waste water treatment and tailings of gypsum, pyrite, copper mine, high silicon containing iron, asbestos and ects [l4-lSJ are the solid wastes used for brick making around the world. There are two kinds of process for brick making, high temperature sintering and low temperature steam curing[19•201. Although the technology of two brick making made great progress and got widely application in construction field, no precedent for preparing sintering-bricks with EMD residue as materials occurred in China because of its complicated processing technics and lack of sufficient practical experience to guarantee the bricks' quality.In this study, EMD residue was mixed with shale and fly ash as the main materials to make solidification/sintering brick. The effects of sintering temperature, sintering time, solid waste content and cooling process on its mechanical properties and toxic elements solidification were investigated according to compressive strength and leaching toxicity."

Jan 1, 2011

By John A. Vallomy

"The CONSTEEL Process introduces a new concept in electric steelmaking by continuously feeding-preheating-melting and refining ferrous scrap or direct reduced iron. The process uses the furnace off-gas and fuel to preheat the scrap in a specially designed preheater. Thermal incineration of the flue gas reduces the carbon monoxide level to the more stringent requirements. Hot water or steam production from heat of flue gas is optional. The tap-to-tap time is set to match the cycle of the caster. The steel is treated via ladle metallurgy. The environment inside and outside of the steelplant is improved by decreasing levels of noise and hazardous emissions. Energy consumption decreases and disturbance to the electric network is eliminated. A CONSTEEL prototype was tested at Nucor Steel, Darlington, SC. A greenfield project is in the completion stage at the Florida Steel plant of Charlotte, NC, USA. The Process PhilosophyThe philosophy of the CONSTEEL Process is not solely to enhance efficiency; this was just a natural result of the change from a batch to a continuous practice. The primary objective in development was four-fold:1) 100% process control2) Rational use of available energy3) Improved environment inside and outside the plant4) Stability of energy input from the power systemIt was to make electric steelmaking more a science than an art and amenable to modern automation.The Basic Concept of CONSTEELThe concept of the process is shown in figure and includes basically a continuous feeding system, a preheater and a melting - refining furnace. A pre-established amount of heat is introduced into the scrap while traveling through the preheater using the sensible and chemical heat contained in the furnace off-gas and additional fuel. Melting-refining is carried out in the electric furnace. Slag formers, slag foaming additions and oxygen are injected to refine the melted steel continuously, to minimize the refractory erosion, to shield the arc, thus optimizing the transfer to the metal bath of the heat generated in the arc, to keep the bath homogeneous in composition and temperature and to produce carbon monoxide (CO) which is fuel for the preheater."

Jan 1, 1988

By Kumar M. Lyer

The channel reactor for ferrous and nonferrous processing has been modeled as a combination of ideal reactors. Cold model studies simulated the counter-current flow of slag and matte (or metal) with high-strength submerged gas injection. A composite model has been developed which describes the mass transfer between the two liquid phases, including the transfer of minor elements. The residence time for the matte droplets in the matte/slag emulsion is compared with the settling rates for the matte droplets in the slag to determine their relative importance in the mass transfer between matte and slag. The governing equations for mass transfer have been developed using correlations for the mass-transfer coefficients in the continuous and dispersed phases. An application of this scheme to a typical copper smelting system is presented.

Jan 1, 1993

By Kenji Sasaki

Tamano Smelter started its operation in January, 1972 adopting FSFE ( Flash Smelting Furnace with Furnace Electrodes ) type smelting furnace at a production capacity of 101,00Ot/y of anode copper and 285,00Ot/y of sulfuric acid. Since then, it had experienced several production expansion program, it had twice as production capacity as start. 196,000t/y of anode copper and 436.000t/y of sulfuric acid. This time, we have completed the plan for increasing production capacity up to 226,000t/y of anode copper and 510,000t/y of sulfuric acid, by the oxygen enriched operation. We carried out several improvements and modifications, changing of cooling system ill FSFE, enlargement of converter and anode furnace, and some progresses in sulfuric acid plant and environmental facilities.

Jan 1, 1993

By E G. Prado

We have confirmed on bench scale the removal of chlorides and alkalies (+95%) and over 2/3 of the zinc, lead and cadmium from EAF dusts. This has been achieved with arrononium acetate solutions alone, or with combinations of water wash, amonia-ammonium carbonate and ammonium acetate solutions. Also confirmed are the process routes for the recovery of the aforementioned elements into marketable products. The technology involves the complete recycling of the reagents. The FAF residue is returned to the electric furnace without risk of impurities buildup. Commercial scale testing with the recycled dust was satisfactory, including quality of the slag and its behavior during the melting stage. A cursory feasibility evaluation is presented.

Jan 1, 1994

By Minh H. Pham

This paper presents a technique for imaging the extent of solidification of molten metal flowing in a cooled pipe based on the concept of eddy currents. A 3D mathematical model, which relates the geometry of solidification to the scattered field induced in a solenoid external to the pipe, is derived. The model is described by a set of integral equations which are solved numerically using the moments method. An iterative algorithm is developed to reconstruct the solidification distribution image. Experimental measurements have shown that the eddy current technique is sufficiently sensitive for practical purposes.

Jan 1, 2001

By Helmut Antrekowitsch

Nowadays nearly the half of the world zinc production is used for galvanizing. After their life span most of the galvanized products return as scrap to the steel mill. During the steel process the zinc is collected in the flue dust It is astonishing to notice that between 40 and 50 % of the zinc produced is brought into the steel processing cycle by the coated scrap while only 3 to 5 % of the zinc production can be covered by the recycling of the zinc-bearing steel mill dusts. Responsible for this worse ratio is the fact that the established recycling technologies suffer from high energy consumption, low zinc yields, halogen problems and hardly any iron recovery. A development of new or an optimization of current recycling procedures for the dusts is unalterable because of increasing zinc amounts in these residues and the rising costs for the disposal. Different pyrometallurgical recycling technologies are tested in rotary kilns and vertical retorts at the Department of Nonferrous Metallurgy, University of Leoben, Austria. Various reducing agents from carbon monoxide to hydrogen and combinations are used. The results should make it possible to draw conclusions that allow an economical and ecological judgement of the different varieties. The goal is to support the affected industry to increase the low recycling rate and prevent a loss of high zinc values in the steel industry filter dusts.

Jan 1, 2003

By K. Osseo-Asare

It is possible to form a two-phase system in certain polymerlinorganic salt/water mixtures, such as those containing the polymer polyethylene glycol (PEG). Such aqueous biphase systems have many of the separation characteristics of conventional solvent? extraction systems, but are environmentally friendlier. Just like the well-known organic solvent/water two-phase system, the top polymer-rich phase is more hydrophobic. and the bottom salt-rich phase more hydrophilic. The partition of dispersed? particles is dependent on the interfacial interaction between the particles and the conjugate aqueous biphase solutions. In particular, the hydrophilic/hydrophobic properties of the surface determine the transfer of the dispersed particles into either the top (more hydrophilic) phase or the bottom (more hydrophobic) phase. Accordingly, differences in the surface chemistry of particles can be exploited to achieve selective separations. In this work, several approaches to separation control will be discussed. using pyrite (FeS2), alumina (AI203). hematite (Fe203), silica (Si02), and titania (Ti02) as model particulate materials. For metal sulfides, pH and redox potential can be used to alter the hydrophobicity/hydrophilicity of the particles. In ?the case of oxides. polymer adsorption and collector adsorption may be exploited to facilitate particle transfer.

Jan 1, 1999

By N. El-Kaddah, A. D. Patel, T. T. Natarajan

The phenomenon of particle migration in a conducting fluid under an applied electromagnetic force field finds its application in selective sorting of minerals and more recently in the removal of inclusion from molten metal. This paper deals with the analysis of the expulsion force and the flow around a spherical particle in crossed uniform electric and magnetic fields in .infinite and in confined medium. Analytical solutions will be presented for the electrk and magnetic fields as well as the induced flow at the limit of zero Hartmann number. The flow around the particle was investigated numerically at low and high values of Hartmann number. It will be shown the magnetic field has almost no effect on the velocity field when Hartmann number is less than 1.0. At higher Hartmann numbers the damping effect of the magnetic field was pronounced in the direction of the applied current. It is concluded that Hartmann number has little effect on the net force on the sphere particle.

Jan 1, 1999