Search Documents

By Fuqiang Zheng, Yufeng Guo, Pengfei Li, Guanzhou Qiu, Tao Jiang, Andrew Yakovlevich Travyanov

Low content of TiO2 and high impurities content of Ca and Mg are the shortcomings of domestic ilmenite. To meet the requirements of the material in the titania produced by chlorination process and titanium sponge industry, enrichment of ilmenite is necessary. In the process of enriching ilmenite, high temperature and reductive condition were beneficial to the formation of anosovite, but the high content of magnesium oxide which was solid soluble in anosovite baffled the following separation. So the effects of pre-oxidation and reductive conditions including reduction temperature, reduction time and hydrogen concentration on the phase composition and metallization rate were studied. The characteristics of reduction samples were analyzed by X-ray diffraction and optical microscope. Results have shown that the reduction product is mainly composed of Fe, Fe(Mg)TiO3 and TiO2 at 1123K, its metallization rate is about 65%,magnesium exists in Fe(Mg)TiO3.

Jan 1, 2015

By Ma Ying

The continuous directional solidification technique of five kinds of special ZA alloys with eutectic, peritectic and eutectoid transformation under the condition of continuous casting by heated mold was studied. The mechanism of surface defects appearing in ZA alloy line was discussed and the structure of some defects were analyzed by SEM. The results show that only when the fitting of various technique factors, pressure head, outlet temperature, pulling speed and cooling condition are reasonable under a certain range, can the ZA alloy smooth line be continuously pulled out. Unreasonable techniques will result in hot tear, rough surface, mush outlet, leaking and other defects. The shape and location of solid-liquid zone have an important influence on the formation of the above defects. When the solid-liquid zone is located in the mould outlet or inner mould, the surface of solidification will protrude into the inner mould. If the remaining liquid cannot counteract the solidification contraction, a rough surface will appear. If the solidification surface further into the mould, the ingot in the mould will have a great friction force when pulling and will form a hot tear. When the solid-liquid zone is moved out of mould, the solidification surface will turn into a plane, which easily results in leaking. A vibration or unstable operation will cause an ingot winding during pulling

Jan 1, 2003

By Qingchun Yu, Baoqiang Xu, Yongnian Dai, Bin Yang, Fulong Zhu

"In this paper, the mechanism of the carbothermic reduction-chlorination process to extract aluminum from alumina in vacuum was investigated. The carbon monoxide (CO) content of the gas, phases of the reduction slag, surface morphology of the reduction slag and the product aluminum were measured by means of gas chromatography (GC), XRD, and SEM. The experimental results indicated that the content of CO in the gas decreased, but Al4C3 increased with time at 1773K during the carbothermic reduction process of alumina. AlCl(g) and graphite (C) were produced by the reaction between Al4C3 and AlCh(g) at 1773K, and then aluminum beads generated after the decomposition of AlCl(g). It implied the mechanism of alumina carbothermic reduction-chlorination process in vacuum involves three steps as follows: the carbothermic reduction of A}z03 to produce Al4C3, the chlorination of Al4C3 by AlCh(g) to produce AlCl(g), and the decomposition of AlCl(g) to produce Al(l).IntroductionAluminum is the basic raw material for many industries [1], and it is used extensively because of various excellent properties such as light weight, good malleability, high strength, excellent thermal conduction, high corrosion resistance and so on [2]. Industrial production of aluminum currently includes refining alumina and electrolytic aluminum processes. However, its development has been effected by some factors such as high energy consumption and heavy environmental burdens [3]. In the past several decades, there had been numerous attempts to produce aluminum by new methods. Extracting aluminum from alumina or bauxite directly by carbothermic reduction-chlorination process had been studied [ 4-6]. Although the alumina carbothermic reduction process [7~9] had been studied, the mechanism of the carbothermic reduction-chlorination process had not been systematically elucidated.In order to investigate the mechanism of the carbothermic reduction-chlorination process in vacuum, GC, XRD and SEM techniques will be used to determine the CO content and to characterize the surface morphology and composition of the slags at various temperatures."

Jan 1, 2011

By Xuewei Lv

An intelligent recognition and quantification system for the micrographs iron ore sinter was developed in the current paper. The average distribution parameters in a gray histogram of minerals by a Gaussian gray distribution model were obtained. The feature curves of the gray histogram of two minerals were achieved by combining the two density functions. The feature indexes, such as the number and position of the peaks and the valleys of two minerals in different ratios, were quantified by differentiating the distribution functions. This algorithm is able to extract the feature of the minerals adequately and accurately for recognizing the composition and phases of the minerals intelligently.

Jan 1, 2009

By Ludy C. Motta, Denise C. O. Nascimento, Sergio N. Monteiro

"Natural cellulose-based fibers are nowadays of growing interest for modern industrial composites. Relatively unknown fibers like piassava, curaua and gourde have shown promising behavior as reinforcement of polymeric composites. However, the hydrophilic characteristics of the natural fibers impair its adhesion to the normally hydrophobic polymeric matrix. Surface treatments can, in principle, improve this adhesion and the fiber/matrix interfacial strength. In this paper, the effect of alkali treatment of the surface of piassava (Atallea funifera) waste fibers was investigated in terms of the change in strength of epoxy composites reinforced with these waste fibers.IntroductionThe consequences of global warming and the increase in the price of petroleum are motivating the use of natural materials as substitute for energy intensive synthetic materials [1]. In particular, natural fibers obtained both, from cultivated plants such as jute, sisal, hemp and flax as well as from industrial waste such as sugar come bagasse and coir, are being considered to replace synthetic glass fibers [2,3]. These natural fibers, also known as lignocellulosic fibers, present the comparative advantages of being renewable, recyclable and biodegradable. Moreover, lignocellulosic fibers require less amount of processing energy and are neutral with respect to CO2 emission, which causes the atmospheric greenhouse effect responsible for the global warming [4]. Low cost is another important economical advantage of the natural fibers over the synthetic ones and the application of lignocellulosic is also associated with a lower wear of processing equipment and better finishing of molded components [5]. Moreover, for some fibers, properties such as the mechanical strength and impact resistance can be superiors to the corresponding properties of synthetic glass fiber [6]. The characteristics and properties of several lignocellulosic fibers are, nowadays being extensively discussed in the literature. It is beyond the scope of this work to comment on the hundreds of papers dealing with this subject. However, there are still less known fibers with great potential as engineering material that deserves investigation."

Jan 1, 2008

By Robert Fritzsch, Ragnhild E. Aune, Mark William Kennedy, Behzad Mirzaei

"The quantitative particle concentration can give important information about the cleanliness of melts for quality control in primary and secondary production of aluminum. Manual quantification of the particle concentration is normally a time consuming process and human control can bias the acquired images and particle count.The present paper explains the automated image-processing steps for the quantification of SiC-particles, with equivalent diameters from 2 to 25 µm, in solidified A356. A total of 700 micrographs, acquired with a standard white light microscope with 10 x magnification, were analyzed. The applied software (Image Pro-Plus 7.0 from MediaCybemetics®) allows for programming of macros which in tum provides the user with a higher degree of control. The automated results are compared with the results obtained by manually counting the particles in the same micrographs. The impact of the automated results on the estimated filtration efficiency was established to be only -3%.IntroductionInclusions are both indigenous and exogenous particulates that are present in commercial metals such as aluminum. If large individual or large numbers of inclusions are present, they can have a significant negative impact on the appearance, mechanical and chemical behavior of products produced from the metal. Aluminum is known to contain large numbers of inclusions: =50 µm in size, e.g. typically <l ppm by volume or <100,000 inclusions of>20 µm per kg of metal as detectable using a Liquid Metal Cleanliness Analyzer, LiMCA [1]. Depending on the final application of the aluminum, inclusions can render the metal 'not fit for purpose', and result in serious economic consequences to metal producers.It is not surprising that the aluminum industry has developed a number of treatment processes to improve metal cleanliness, given the large number of high value products whose quality can be adversely affected by inclusions. CFFs are the most commonly applied filtration process and have been used to filter >50% of the world production of aluminum since the 1990's [2].Inclusions in aluminum may be particles, bifilms [3] or clusters of: oxides (Al2O3 , SiO2), spinels (MgO· Al2O3), carbides (SiC, Al4C3), nitrides (AlN), borides (TiB2), sulfides, phosphides and intermetallics [ 4]."

Jan 1, 2013

By Roger Agnew

Sulphide ores mined by Inco Limited in the Sudbury District contain small quantities of cobalt. During beneficiation, cobalt distribution to various streams is similar to nickel. After smelting, nickel is selectively extracted by carbonyl refining and the cobalt remains in the carbonylation residue. This residue is processed in a specialized hydrometallurgical plant to produce precious metal residues, copper cathodes, and a nickel- cobalt carbonate intermediate product. The nickel-cobalt is shipped to Port Colborne where the cobalt is separated as cobaltic hydroxide and refined to metallic cobalt. This paper deals specifically with the recently constructed Electro Cobalt Refinery. The cobaltic hydroxide is dissolved and residual zinc, copper and nickel are removed by ion exchange and organics by a carbon column. The purified cobalt solution is fed to the electrowinning circuit where cobalt rounds are produced on stainless steel mandrels. In the design and construction of the refinery, special attention was directed to materials of construction both for the process equipment and the physical plant, operating control and flexibility, and the quality of the working environment. The end result is an efficient and clean operation which yields a product of excellent quality.

Jan 1, 1988

By Jose Lara

SIDOR has developed a setup model for a roughing mill with edger that optimizes the position of the edger for a better control on the width, optimizes the efficiency of the mill for controlling of the profile of reductions and increments of the speed rolling and improves dimensional performance. This model consider as data entry, the number of passing, incoming and finish thickness and width, hardness and temperature of the material. The setup model is based on the equations of Ekelund for the width spread calculation and estimates of the rolling force. Additionally this model employ a Newton&apos;s algorithm for resolving the optimal position of the edger. The preset values calculated by setup model is the horizontal screw position, vertical screw position (edger), threading and rolling speed, some parameters calculated for the correction of ski. In the revamping of the roughing mill of hot rolling of SIDOR, C.A, carried out in January of 2005, it was implemented this setup model and the coefficients and parameters were adjusted for the first 15 days. Starting from there the values of preset, send to roughing mill are calculated by this setup model. The current indicators show an enhancement of 18% in the roughing mill effectiveness and a decrease about 37% in the mill stop by overload in the motors.

Jan 1, 2006

By Uday Pal

In direct reduction processes for iron and steel making, significant amounts of Fe-C alloy droplets are generated and these remain suspended in relatively low FeO (around 5%) containing slags. Earlier workers have found that when the FeO content in the slag is <5%, the decarburization reaction becomes extremely slow (virtually ceases to occur) even though the alloy droplet contains a significant amount of carbons (2-3%). Understanding this rate controlling kinetic phenomena is crucial to designing an&apos; optimum direct steel making process. We studied decarburization of Fe-C particles by low FeO (<5%) containing CaO-SiO2A12O3 slags and found that by putting both the droplet and the slag in direct contact with an inert electronically conductive member that extends deep inside the slag bulk were able to quickly and completely decarburize the droplets. A detailed description and an explanation of the process will be presented.

Jan 1, 1995

By Klaus Gamweger

There are different reasons for purging a metal bath. The operations are varied, for example the purging gas can be used as a reactive gas being part of the metallurgical process or as an inert gas using the rising gas bubbles for agitation only. The different purposes for agitation, chemical and thermal homogenization or a preferential movement of the slag to the slag skimming door have to be considered. It depends on the furnace type and its dimensions as well as the process characteristics what the focus is on. For an optimized arrangement of numbers and position of all single plugs in the furnace, mathematical modeling - the CFD Computational Fluid Dynamics method - is used. This paper shows how the operation of purging plugs can influence the metallurgical process of an anode furnace by the example of Jinchuan Copper in China. The potentials for savings in energy consumption as well as in time for oxidation and reduction are presented.

Jan 1, 2006

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 Junzo Hino

Most of the waste that contains a small portion of copper is landfilled. The recycling process of copper from the waste, such as shredder residue, should be developed in order to save mineral resources and prevent environmental pollution. Shredder residue, generated from disposed automobiles and electric appliances, consists of many types of plastics, glasses and metals. The combustion heat of plastics is efficiently used for smelting in the recycling process that consists of melting and reduction. Because the waste contains numerous components the knowledge of the distribution behaviors of the main components is necessary to develop the recycling process. The distribution behaviors in the recycling process are evaluated by using the thermodynamic calculation program, HSC Chemistry. The calculation results are compared with the practical operation data of the recycling process and discussed.

Jan 1, 2003

By Art Johnston

Gas handling at Magma Copper Company&apos;s, San Manuel smelter receives process gas from a flash smelting furnace and four copper converters. The major gas handling equipment consists of four electrostatic precipitators and a sulfuric acid plant. Process vessels in gas handling are typically confined spaces. Lethal gases., mechanical and chemical hazards, and the difficulty of rescue, should an accident occur, makes this area a must in the safety plan. The presence of hazardous chemicals and explosive gases in process vessels and piping are of major concern when repairs are required. Proper job procedures are critical to prevent injury during repairs. This includes plant employees and contractors who are likely to be unfamiliar with the hazards involved. The safe operation of a gas handling operation must include the functions of operations employees on a daily basis. This includes a safe working environment and involvement. of all employees in the safety program. If an injury does occur quick medical response is critical to prevent serious injury. Medical responders must be adeqliately trained and prepared to treat the injured person without becoming victims themselves.. The methods used at Magma copper Company to deal with these safety problems are the focus of this presentation.

Jan 1, 1992

By K. Fagerlund

In this work, the rate of dissolution, melting behaviour and phase separation of silica flux with molten slag and matte were investigated. Mutual dissolution between high-grade matte and silica was chemically determined. Silica dissolution rates ,in various iron silicate slags was determined using the rotating rod method. The reaction and separation phenomena of slightly oxidised chalcopyrite samples and cuprous sulphide-magnetite mixtures with silica sand were examined all about 1350°C. The samples were water quenched, and polished specimens were studied and analysed using a light optical microscope ,and a scanning electron microscope with energy dispersive spectrometer. The silica dissolution rate in slag was found to increase with decreasing silica content and increasing ferric iron content. The reaction rate of silica sand&apos; with matte was found to increase with increasing oxidation degree and magnetite content of matte:

Jan 1, 1998

By Qian Li, Li-chen Hou, Yong-bin Yang, Tao Jiang, Jian-jun Hu, Bing Xu

Extraction of gold from refractory gold concentrates usually requires an oxidation step to remove arsenides、sulphides and carbonaceous matter. In this investigation, the gold concentrates were two-stage roasted under different atmospheres and temperatures. Results indicated that at the first stage, under neutral atmosphere, the removal rate of arsenic increases as the temperature rises. Under the oxidizing atmosphere, with the increase of temperature, arsenic content in the residued calcine increases, in addition, the volatilization of arsenic is also affected by the oxidation of carbon that generated CO, which is advantageous to the decomposition of arsenate decomposition. At the second stage of roasting, it is the higher temperature and stronger oxidizing atmosphere, the faster sulfur and carbon oxidated rate is, but at the same time, the calcine appears the phenomenon of consolidation because of the phase of silicate compounds generate.

Jan 1, 2015

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 Alim Ullah

Process, quality and management control are necessary in order to produce DRI of required quality and at minimum cost. Although the characteristics of the two (2) principal inputs, that is, iron oxide feed and natural gas (for gas-based DRI plants) can affect the operation of a DRI plant significantly, they are outside the control of plant operators, at least in the short run. The quantity of reduction gas, its composition and reduction gas temperature are some of the key process variables. Statistical Process Control (SPC) can be used in a DRI plant to minimize the production of off-grade material and costs, as well as to improve the overall operation of the plant. One of the key quality variables to be measured and controlled is percent metallization, defined as FeM/FeT*100 where, FeM and FeT respectively are metallic iron and total iron in DRI. Control charts are used to monitor the quality of DRI produced and, when necessary, corrective actions are taken to bring the product back within the control limits. Management control can consist of essentially following how well the plant performs against some pre-established standards of parameters like daily production, downtime, consumption of material and energy, etc. In this respect, it is suggested that yield, defined as theoretical consumption/actual consumption of iron oxide feed, be used to monitor the consumption of feed material. Similarly, instead of using natural gas per ton of DRI produced, a better criterion would be efficiency, defined as theoretical natural gas consumption/actual natural gas consumption.

Jan 1, 2006

By Junji Shibata

Waste solution from the Ni non-electric plating process contains 4.0 kg/m3 Ni, 0.1 kglm3 Fe, 0.0 I kg/m3 Zn, 48 kg/m3 S042-, 98 kg/m3 HP032-and 31 kg/m3 laetic acid as a typical composition. Solvent extraction, cementation, ion exchange resin and precipitation methods are possible to use for the treatment of this kind of solution. In this study, solvent extraction of Ni was investigated using two kinds of extractants to clarify the relation between extraction percent and pH for various extractant mixtures. As Ni ion has an octahedral structure with ligands, the synergistic effect for Ni extraction is considered to take place in solvent extraction using two types of extractants. The investigation of the synergistic effect for Ni extraction was carried out in case of various extractant systems.

Jan 1, 2003

By Andreas Nolte

This paper includes a comprehensive report about the metallurgical utilisation of reusable products from electronic scrap recycling, car shredding industry, used glasses an various waste products, such as slimes and flue dusts, generated in a secondary copper smelter. Depending on the copper content, the type of copper compounds and the characteristics of accompanying substances, the materials are treated by smelting in furnaces, operating under reducing or oxidizing conditions. HKs pyro- and hydrometallurgical processes, blast furnaces, converters anode furnaces, tin lead alloy plant and tankhouse will be outlined. The reusable products are categorized according to the origin of the materials and then presented in the form of quantity and quality balances. Processing methods, process able quantities and quality requirements of inputs are described. The utilization degree of the most important metals (copper, tin, lead and zinc) is described with graphics. The report is rounded by information on operating licence according to the environmental regulations of the Federal Republic of Germany and data concerning supply and contracts

Jan 1, 1997

By Zheng Wei, Jian Cheni, Zhenliang Weng, Wei Liang, Hongbo Zhu, Jinhui Peng, Linqing Dai, Qianxu Ye

"By testing the dielectric constant and the dielectric loss factor of concentrated Dahongshan, mill scale, anthracite and light-burned dolomite in different frequency and temperature, and by studying the temperature-rising characteristics of the materials in the microwave field of 2.45GHz in frequency, the research in the paper shows that to reach at 1250°C under the same condition -2KW the microwave power and 30g the mass --the time concentrated Dahongshan takes is 330s, whereas the millscale is 855s and the anthracite is 820s. About the last one, the higher the temperature is, the stronger the absorptivity is. After the temperature has rose to 400°C, the anthracite's absorptivity increases dramatically. The result of the research would serve as the foundation of the further study on making direct reduced iron by microwave heating.1. IntroductionUnder the microwave fields, materials' dissipation of dielectric bodies would generate thermal effect. Therefore, the dielectric constant and the dielectric loss factor are closely related to materials' ability of absorbing microwave energy-the larger the dielectric constant and the dielectric loss factor are, the stronger the material's ability of absorbing microwave energy is, and the better the thermal effect would be[1-2]. In order to research how to make reduced iron from iron ore fines by microwave heating deeply and systematically, the test of raw materials' dielectric constants and dielectric loss factors are of the essence. What's more, because a mineral' conductivity is influenced by its components and crystal structure[3], it is necessary to study different materials' different temperature-rising characteristics; hence such studies would provide theoretical foundation of further research."

Jan 1, 2012