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By Yuanbo Zhang, Zhixiong You, Guanghui Li, Peidan Wen, Tao Jiang

Sn-bearing iron ore containing small amount of Zn, Pb and As is one of the typical complex polymetallic ores in China. This kind of ore is not extensively utilized due to the complicated relationships between iron and other associated nonferrous metal minerals. Excessive contents of these elements would adversely affect the metallurgical operation as well as the quality of steel products. In this study, reduction behavior of Sn was detailedly investigated using H2 or mixed H2/CO as reductant. The results revealed Sn volatilization was improved in the presence of H2 than individual CO/CO2 atmosphere. Simultaneous volatilization of these elements was realized by roasting under weak H2/CO reducing potential, and metallization reduction was advantageous for further Zn volitilization. A metallic pellet (DRI) with Fe metallization greater than 90%, residual Sn, Zn, Pb and As content of 0.054%, 0.012%, 0.0045% and 0.09% was prepared via a simulated reducing gas of coal gasification.

Jan 1, 2015

By LuisW. Pommier

The industrial wastes generated by the plating industry, the circuit board manufacturing industries and other related industries normally contain high concentrations of metals, which make them hazardous. The extraction of the contained metals and their separation may be achieved by both pyro and hydro metallurgical processes. Some of the industrial wastes, those rich in some metals like nickel for instance, are being treated like mine ore concentrates and are being fed to smelting furnaces. The slags from these smelter operations are hazardous. They have, however, special environmental dispensations issued by the regulatory authorities. Hydro-metallurflcal processes have been reported. They also generate a residue which is hazardous because not all the valuable metals are leached out and also, because "non valuable" components, like chromium, are less readily leached. Residues from the plating industry, containing nickel, copper. zinc, iron and chromium as the major constituents and also sodium and calcium, together with cadmium, cobalt, lead. manganese, magnesium, molybdenum, and potassium, have been processed for the extraction of the valuable components. The generation of electrolytic nickel, copper and zinc and also of ferric chloride and chromium oxide is reported. The operation is achieved by a caustic leach for the extraction of zinc, followed by a sulfuric acid leach for the extraction of nickel and copper. This acid leach also extracts the iron and some chromium. The nickel copper and zinc are rendered pure by electrolysis, the iron is oxidized for the production of ferric chloride and the chromium is recovered as an oxide. The leaching operation is performed in two stages, first at a pH of 2.5 to generate an electrolyte for the partial recovery of the metals and then at a pH of 0.5 for the complete extraction of the metals. This leaching operation generates a residue, which although small in volume compared to the initial feed, still contains traces of the valuable metals and a portion of the chromium which makes it hazardous. Additional leaching with hydrochloric acid or nitric acid is required for its complete dissolution. The other minor constituents mentioned are present in concentrations each of less than 0.1% and are handled as impurities in the process. The metals which are soluble at a pH 0.5 and precipitate between 0.5 and 2.0 are bled off. Other impurities will concentrate on the raffinate from the solvent extraction operations from whence they are bled off. These bleeding streams are hazardous and the "impurity metals" are now present in concentrations which would make them valuable, however, the size of these streams is so small that they do not warrant their processing, however they could be marketed to specialized smelters. The extraction of the valuable metals, of the hazardous constituents, the generation of a marketable mixture of minor constituents and the production of a non-hazardous residue for declassification is profitably achieved.

Jan 1, 1998

By E. C. T. Chao

Micro-optical and synchrotron radiation-induced X-ray fluorescence (SXRF) techniques have been used to study unoxidized and oxidized samples of Carlintype sedimentar,y rock-hosted disseminated gold ore. In these samples, Where much of the gold is submicroscopic, the SXRF technique, which has a spatial resolution of about 20 ~m and a minimum detection limit (MDL) in the ppm range, is an ideal and necessary tool for precisely locating gold-rich areas in a sample. Gold-rich areas pinpointed by SXRF were later studied in detail by micro-optical methods, principally optical microscopy and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX). In two unoxidized and one oxidized ore samples, SXRF analyses have shown gold to be present predominantly in discrete clay-rich and silicified areas. Gold was not detected by SXRF in association with pyrite or carbonaceous materials. SEM-EDX examination of the gold-bearing areas in the unoxidized samples succeeded in identifying only two free gold particles, 0.2 and 0.5 ~m in size. In the oxidized sample, gold particles appear to be larger (but still submicroscopic) in average size and more evident in micro-optical examination after SXRF location of goldbearing areas. The findings of these studies may help to improve the efficiency of processing and recovery of gold from unoxidized ores.

Jan 1, 1987

By Peter Stiaszny, Andrej Samoilov, Yuri Titovets, Gottfried Hribernig, Nikolai Zolotorevskii

"The model has been developed to simultaneously predict both transformation product portions and mean ferrite grain size from the same common · principles as a result of the austenite decomposition during any cooling path of dual phase steels. The transformation products considered are polygonal ferrite, pearlite, bainite and martensite. The model is based on the classical equations of nucleation-growth theory and also contains some empirical parameters. The chemical driving forces for nucleation and composition of elements at the phase interfaces are derived by computation thermodynamics. The empirical parameters related to the model were determined on the basis of a series of austenite transformation dilatometric curves and grain size measurements for continuous and interrupted cooling of several steel types. The model is aimed to predict phase transformation in the complex cooling conditions of the run-out table of the hot strip mill at YOEST-ALPINE STAHL LINZ GmbH as a part of the computer aided system for prediction and on-line controlling of the mechanical properties of hot-rolled strip.IntroductionThe term ""dual phase steels"" is used to refer to a steel consisting essentially of a dispersion of martensite in a fine-grained ferrite matrix. These steels are of increasing technological interest since they provide a better combination of strength and ductility than any other conventional steel sheet material. The strength is important because it offers an opportunity to produce lighter components, while good ductility is needed to permit easy forming of components. It is generally recognized that martensite plays an important role in determining the strength level of dual phase steels. A full understanding of the role played by the phases in determining such characteristics requires investigating in more detail how to optimize the martensite level of such steels, while maintaining good ductility remains the subject of continued research in the industry."

Jan 1, 2000

By S. Katz, V. Stanek, K. L. Moore, E. D. Larsen, D. E. Clark, P. E. King

"Cupola melting is a complex physical and chemical process having a number of nonlinearities which make conventional process control difficult. In addition, sensors for both inputs and outputs of interest to the foundry operator are often difficult or impractical to apply in a production situation. The present work is an effort to control the process using both intelligent and conventional control techniques as appropriate. Neural networks are used as an inverse process model in a cascade, feedforward controller in conjunction with a finite difference model of the cupola. A separate implementation of the neural net serves as a stand-alone visualization tool; it can operate on a laptop computer and is a useful tool for the cupola operator. IntroductionThe goal of the present work is to develop a controller to improve the efficiency of cupola melting. Although cupola melting as a process has a long history, automatic control has been elusive because the process has been poorly understood. The purpose of this four-year program, which has been underway for about six months, is to develop a controller for the cupola process using intelligent and conventional control methods.The Cupola ProcessThe cupola furnace [1,2] is one of the oldest processes for making cast iron, and is still the dominant method. It takes the form of a water-cooled vertical cylinder, as large as 4 m in diameter and 20 m tall. The charge consists of scrap metal, alloying ingredients, limestone, and coke, which serves as fuel; it is composed by weight and fed through doors near the top of the cupola. Air, usually heated and often enriched with oxygen, is blown in near the bottom through tuyeres extending a short distance into the interior of the cupola. As the coke is consumed, the charge drops and melts. A continuous flow of iron emerges from the bottom of the furnace, at rates as high as 100 tons per hour, and. is transferred to casting lines in the foundry. The exhaust gases are drawn from the top of the cupola, where they are processed to meet pollution standards."

Jan 1, 1994

By Peter R. Whiteley

"This paper discusses gaseous, solid and liquid injection technologies employed in the aluminium industry. The reasons for injection systems are presented, together with a description of the processes used. This includes a review of injection in crucibles, furnaces, launders, and into special purpose metal treatment boxes. The paper covers both the primary and secondary aluminium industries. IntroductionMany injection technologies are used in the aluminium industry and are in a rapid state of development. This paper provides a review of these systems and presents some thoughts on the possible future application of injection to further improve productivity and reduce losses associated with current applications.The Needs for InjectionThere are many issues facing the process metallurgist in the aluminium industry which call for the application of injection technologies now and in the future. In order to categorise these issues the industry may be broken into primary and secondary aluminium, although some of the concerns occur in both areas.The forementioned issues are variously concerned with improving metal quality, improving productivity, and reducing process problems.The use of injection techniques will be discussed under the heading of solid, gaseous and liquid injections, and the objectives and benefits of each covered briefly."

Jan 1, 1996

By Sue Ritz

Gold extraction has relied on coconut carbon in adsorption circuits for several decades. IXOS®, invented by 6th Wave Innovations of Salt Lake City, Utah, is a new type of adsorbent that exceeds the selectivity of carbon and improves on the mechanical properties of other available resins. IXOS selectivity against copper cyanide complexes allows it to be used in circuits that currently struggle with copper contamination. IXOS potential to eliminate or reduce the application of SART technology will expand the opportunities to exploit more complex precious metals deposits. This paper will describe the technology behind IXOS molecular imprint, its comparison to carbon adsorption in the field, and the effect of efficiency on long-term recovery from heap leach METSIM simulation software.

By Linda C. White

The use of red mud, a waste product of the ?Bayer? process for bauxite refining, was investigated for its arsenic removal effectiveness from aqueous solutions under various conditions. Red mud efficiently removed As(III) between a pH range of 7.6 and 9; and As(V) in the pH range between 5.5 and 6. Pre-washing of the red mud with salt water considerably improved its arsenic adsorption capabilities. With appropriate red mud dosage, the residual arsenic in solution was decreased below the regulated acceptable arsenic limit (0.1 mg/L) from aqueous industrial wastes. The arsenic adsorption followed first-order rate kinetics and fitted the Langmuir isotherm model. Results suggest that red mud is potentially a useful adsorbent for removal of arsenic from contaminated water or industrial waste solutions.

Jan 1, 2003

By Jian-hua Ren, Guang-liang Wu

A lot of dust is produced in iron and steel enterprises, giving rise to serious environment pollution, with which all countries are trying to find methods to deal. The influence of relevant technological factors on dephosphorization was investigated in laboratory, and the effect laws of that were analyzed. The results demonstrate that, in the given conditions of the best slag-metal proportion for hot metal dephosphorization is 1:10, and the optimum temperature is 1350 , The phosphorus distribution ratio of dephosphorization agent containing converter dust of 30% has the maximal value, with dephosphorization rate reaching 85%. Under the optimal conditions, premelting dephosphorization agent can significantly improve the ability of dephosphorization, dephosphorization efficiency increasing to 92%. Therefore, the dust can substitute the oxidant and fixative of dephosphorization agent, be used in hot metal dephosphorization, to enhance the efficiency of utilization.

Jan 1, 2016

By P. H. Chang, J. E. Gould

"Solidification structures and austenite decomposition in some spot welded O.05%C - O.3%Mn steels have been studied with the aid of a numerical thermal model. The model is a one dimensional finite difference formulation, and accounts for melting, temperature dependent thermal properties, effective heat transfer in the liquid, and contact resistances. The model was used to predict solidification conditions during resolidification of the nugget. These solidification conditions were correlated with the primary dendrite spacing using available primary dendrite spacings modelling. The model was also used to predict cooling rates in the temperature regime for austenite decomposition. These cooling rates were used to interpret the underlying microstructure.INTRODUCTIONThe metallurgical transformations which occur during the spot welding of low carbon steels have traditionally been characterized only in the most general of fashions. This is most probably due to the similarity of spot welded microstructures to other welded microstructures, and that the mechanical integrity of spot welds has not been a concern. In addition, little information about the particular thermal cycles experienced during spot welding has been available. The introduction of HSLA (microalloyed) sheet steels has, however, raised new concerns about the integrity of spot welds. These steels have on occasion shown irregular weldability, as well as brittleness in the weld nugget on destructive testing l - 4 .In response to these concerns, considerable work has been done attempting to characterize thermal cycles in spot welds 5-12. This has largely taken the form of thermal modelling, with the end purpose generally to estimate the size of the nugget formed. This work uses the thermal model developed at Inland Steel 13 ,14 to try and understand, in a more fundamental way, microstructural evolution in spot welds. Two facets of this microstructural evolution are examined in detail:"

Jan 1, 1986

Smelter operating and environmental requirements demand high on-stream time (high reliability) from the primary smelter sulfur retention device - the sulfuric acid plant. The key to reliable smelter sulfuric acid plant operation is the gas cooling and cleaning system. Problems in the gas cleaning system cause corrosion, plugging, equipment failure, etc - plant down time, in the contact section of the plant. The last fifteen years have seen major changes in gas cleaning system design to the current standard of brick lined venturi scrubber, packed gas cooling tower with plate type liquor coolers and lead or plastic tube precipitators. The current-design offers improved impurity scrubbing along with increased reliability. In addition, a number of alternate gas cleaning systems have been offered. Chematics LAB System: Monsanto DuPont Dynawave System; Lurgi venturi scrubber with lead star gas cooler. This paper will review the design and operating advantages, disadvantages, and risk of the standard gas cleaning system and compare it to the alternate systems.

Jan 1, 1992

By Byung-Su Kim

The reaction between calcium sulfate and hydrogen is of interest both as a means of regenerating calcium sulfide as a reductant of sulhr dioxide to elemental sulhr and for producing elemental sulhr from gypsum. This reaction was investigated using a thermogravimetric analysis technique in the absence and presence of nickel catalyst. The reaction temperature was varied between 973 and 1153 K, while the hydrogen partial pressures of 12.9 - 86.1 kPa were utilized. At 1073 K and a hydrogen partial pressure of 86.1 kPa, 60 % of the original calcium sulfate in the absence, and 95 % in the presence, of the nickel catalyst was converted to calcium sulfide in one hour.

Jan 1, 1999

By Mariana Barcelos, Frederico Muylaert Margem, Giulio Rodrigues Altoé, Pedro Amoy Netto, André Gomes, Sergio Neves Monteiro

Environmentally correct composites, made from natural fibers, are among the most investigated and applied today. In this paper, we investigate the mechanical behavior of polyester matrix composites reinforced with continuous fique fibers, through bending tensile tests. Specimens containing 0, 10, 20 and 30% in volume of fique fiber were aligned along the entire length of a mold to create plates of these composites, those plates were cut following the ASTM standard to obtained bending tests specimens. The test was conducted in a Instron Machine and the fractured specimens were analyzed by SEM, the results showed the increase in the materials tensile properties with the increase of fiber amount.

Jan 1, 2015

By A. Navarra

Peirce-Smith converting (PSC) is applied for roughly 50% of primary nickel and 70% of primary copper production. PSC cycles produce batches of ironfree sulfide matte (or blister copper, in the case of copper smelters), that are subject to further processing. However, the number of cycles that can be performed simultaneously is limited by the offgas handling system. Moreover, PSC suffers from variation in the yield and duration of the cycles. This variation is managed by conventional smelter designs, in which the upstream smelting capacity exceeds the nominal converting capacity; PSC is thus a major bottleneck in conventional nickel and copper smelters. Stabilization and standardization of PSC operations can therefore increase smelter throughput. The current paper presents a discrete event simulation (DES) framework to assist in smelter debottlenecking. It features random number generation to represent cycle variability, and time-adaptive finite differences to represent thermochemical complexity. Preliminary computations are presented.

By Toshiaki Nakai, Kunihiko Takeda, Kimio Imaizumi, Hiroaki Shirasaka

"The new type of nano-porous silica particle was considered to be constructed by the spinodal decomposition-type process which was found to have narrower pores than those of conventional porous silica prepared from boron silicate or ""Shirasu"" balloon. Nano-porous silica particles were fabricated by the calcination of silica gel mixed with well-dispersed complex salts composed of phosphorous and molybdenum compounds. Both silica and inorganic salts were not perfectly dissolved in the suspension solution. After removing of the water, the silica-inorganic salts complex was volatized and successively calcinated at a temperature ranging from 650 °C to 800 °C. Then, the inorganic salts were removed by dissolving in hot water. Other inorganic salts such as potassium halides were also found to be effective as a pore-size controller.IntroductionControl of structure has an important role in the field of industry as well as in the separation and purification technology for metals and organic syntheses. Many studies on the control of material structures have been reported regarding porous materials with pores ranging from nanometer to micrometer scale. 1 ) One example is zeolite as a naturally yielded porous inorganic material. Various types of synthetic zeolites have been studied as ""molecular sieve"" materials with ordinary pore-size of less than one nanometer. In 1992, crystalline meso-porous material with a large surface area named MCM-41 was synthesized through the use of template synthesis. 2) In direct relation to our study, amorphous borate glass having 4 to 100 nm of fine pores known as Corning glass 3l or SiO2-Al2OrB2O 3-CaO porous glass having large pore dispersity ranging from 4 to 10,000 nm have been reported. 4 ) S) 6 ) Some examples of several reported studies are as follows: phase-separated porous glass consisting of B2OrAl2O3-ZrO2-RO-R2O complex oxide 7 ) glass with finer pore induced from hydrolysis of silane alkoxide, porous material attained by condensation polymerization through the use of sol-gel process 8), alumina meso-porous material 9 ) 10), silica-zirconia material 11), carbon porous material 12), etc.."

Jan 1, 2000

By K. B. Shedd

Questions regarding possible adverse health effects from exposure to zeolites arose when the inhabitants of two villages in Turkey were found to have high incidences of mesothelioma, a disease generally identified with exposure to asbestos. No asbestos deposits are known in the area, but some fibrous zeolites have been found. Further investigations have resulted in conflicting opinions as to whether fibrous zeolites are related to the high incidence of mesothelioma in Turkey. The U.S. Department of the Interior, Bureau of Mines examined the habits of domestic zeolites by scanning and transmission electron microscopy. Only erionite and mordenite particles possessed acicular to fibrous habits. With the exception of a rarely occurring woolly erionite sample, the fibrous zeolites were not dimensionally equivalent to asbestos.

Jan 1, 1982

By Yang Guangqing, Shao Jiugang, Zhang Jianliang, Wan Dan, Fu Yuandi, Guo Hongwei

"Resource of metallurgical coke is becoming scarce, and although coke can be partially replaced by pulverized coal injection, there are many restrictions for further increase in coal ratio. Mixed charge of ore and lump coal from top to replace more coke was studied in this paper. Softening-melting property of the burden was affected by charge of lump coal. Softening-melting properties of mixed charge of ore and coke, mixed charge of ore and lump coal were tested respectively. Results show: the property of the burden mixed with coke is superior to the burden mixed with lump coal; lump coal would not deteriorate softening-melting property of the burden and some of them can even improve softening-melting property of the burden. Top charge of lump coal would not deteriorate softening-melting process, and this should be a new way to increase coal consumption to decrease coke rate.IntroductionThe blast furnace is still the predominant process for the reduction of iron ore and will probably remain so for the next decades. Metallurgical coke is becoming scarce and expensive, so the cost of hot metal can be decreased by reducing the consumption of metallurgical coke[l]. Coke can be partially replaced by pulverized coal injection, currently the highest rate of pulverized coal reached 266kg/tHM, most of blast furnace PCR is about 150kg/tHM, and it is very difficult to further increase of PCR. Nut coke is charged into blast furnace mixed with iron ore, not only for improving utilization of metallurgical coke, but also for lowering the coke rate. Presently the majority of blast furnaces in the world use nut coke although its amount is very different: from 10-20 to 70--100 kg/tHM and more[2-4].The effect ofnut coke in blast furnace is extensively researched, and the main conclusions recommend: to improve gas permeability of cohesive layer in blast furnace, to promote reduction of iron burden, protect metallurgical coke from the solution in the shaft due to higher reactivity of nut coke. There is no special requirement for the strength of nut coke[5-8]. Nut coke is also used for sintering fuel, which may lead to the shortage of the nut coke charging into blast furnace. So lump coal mixed with iron ore is considered to be charged into the blast furnace, not only to reduce the cost of grinding coal, but also to increase the use amount of coal."

Jan 1, 2013

By Klas G. Hultbom

Mercury is present as trace contaminant in many raw materials for metallurgical plants. When such materials are treated with pyrometallurgical processes the mercury is volatilised. Mercury has a high vapour pressure, even at low temperatures, and therefore it is removed only partly by normal gas cleaning processes. The Boliden Norzink scrubbing process removes elemental mercury by converting it to calomel. It is widely used in the base metals industry. This paper gives examples of the application, and also outlines the background for the development of the process. Another technology developed by Boliden for mercury removal is the Selenium filter. This is a fixed bed filter based on the reaction between elemental gaseous mercury and selenium, by which mercury selenide, HgSe, is formed. The mercury selenide is a highly stable compound with extremely low solubility in water and very low vapour pressure. Mercury is removed selectively without any side reactions. Special applications for the selenium filter technology include mercury removal from gases containing sulphur dioxide and geothermal off-gases.

Jan 1, 2003

By Marcio B. Fonseca

Nickel-cobalt laterite deposits have become the focus of attention for hydrometallurgical processing. Following the lessons of the second generation high pressure acid leach (HPAL) projects in Western Australia other Ni-Co laterite projects are now evaluating potential HPAL projects with a rigorous integrated approach that begins with geological modeling, resource estimation and metallurgical studies. The Vermelho nickel-cobalt laterite deposit has been under exploration and study for several years with investigations of various metallurgical processes. Recent HPAL studies have indicated that the nickel and cobalt laterite at this deposit is amenable to upgrading by silica rejection followed by pressure leaching. These studies have required a detailed geological investigation to generate a new resource model. The recent development of a sophisticated geological model integrated with a multi-element resource estimation for this complex tropical nickel laterite deposit in northern Brazil provides an example of the contribution of geology at the critical project stage where process technology decisions are made on relatively small samples of the total resource.\ Keywords: Ni Laterite, Geological Modeling, Resource Estimation

Jan 1, 2004

By F. M. Wang, J. P. Lin, G. Y. Tang, H. C. Zhou, Y. F. Liang, F. Ye

"Fe-6.5%Si alloy is a very excellent soft magnetic material compared with conventional Si steel (Si content ~ 3.5%), especially in high frequencies with reduced iron losses and noises. But it is hard to be fabricated due to its brittleness at room temperature. Dynamic electropulsing is applied to the cold rolled Fe-6.5%Si sheet during tensile deformation. Mechanical and microstructural properties are investigated with different electropulsing and strain rate. It is found that the yield stress decreases and the elongation increases dramatically with the application of dynamic electropulsing. It is indicated that the work hardening could be reduced with the dynamic electropulsing during deformation, which provides a promising way to fabricate this alloy sheet much easier.Introduction Fe-6.5%Si (weight percent, same as below) alloy has more excellent soft magnetic properties compared with conventional silicon steel (Si content ~ 3.5%), such as higher resistivity, higher permeability, near zero magnetostriction, etc. and exhibits much lower core losses and noises [1]. However, Fe-6.5%Si is very brittle at room temperature and hard to be fabricated in strip by conventional hot-cold rolling process [2]. This lack of low-temperature ductility has been generally attributed to structural ordering ofB2 and D03 phases [3]. Several methods have been developed to avoid its brittleness, such as chemical vapor deposition (CVD) [4], rapid quenching [5, 6], dipping and diffusion [7, 8], direct powder rolling (DPR) [9], etc. However, hot-cold rolling method is still of interest for industrial applications. In our previous work, this alloy can be cold rolled after certain thermomechanical process and heat treatment [10-13]. The cold rolled sheet exhibits some extent of ductility [11]. However, side cracks are common for the rolled sheet, it is very necessary to improve the ductility of this alloy by other technical applications."

Jan 1, 2012