Search Documents

By Z. Y. Xie

The visualization techniques were employed for the analysis of computer simulation studies of dislocation core structure in ordered alloys. Atomistic computer simulation was used for the study of the local configuration of the material in the vicinity of the dislocation. Stresses were applied in the simulation in order to study the necessary stress level for the dislocation to move and onset plastic deformation of the material. The results were analyzed in terms of the strain tensor as a function of the position (x, y) in the material with the dislocation located at (0, 0). Various visualization packages are used to plot the invariants of this strain tensor and to visualize the changes that the dislocation core undergoes under stresses until it finally moves.

Jan 1, 1993

By John L. Watson

Many metals-based industrial processes experience limitations in their operations due to an inability to effectively separate solids and liquids where partidesizes are less than 25 microns. Steel plant sludges ,generated, from the cleaning of furnace off-gases represent a typical example of processing difficulties attributable to material characteristics, and recycling or even efficient disposal of these materials is often a major problem. The use of a magnetic field to augment the traditional mechanisms of vacuum dewatering has, been demonstrated in previous work to have significant value in separating solids and 'liquids, where the solids exhibit some magnetic character. Magnetic vacuum dewatering has been used with magnetite ores and with blast furnace sludges and magnetic fields have been incorporated successfully in drum and disk vacuum filters. The research described in this paper investigates the use of magnetic seed material and flocculants to extend the application of magnetic, vacuum filtration to non-magnetic pulps. It is shown that the addition of a flocculant can enhance the capacity of drum and disk magnetic fIlters when treating materials, such as steelmaking sludges, which are only partially magnetic. In addition, the use of seed magnetite with a flocculant is shown to improve the dewatering of fine hematite pulps in a drum magnetic filter. However the use of a flocculant and seed magnetite had only limited success in improving filtration in a disk magnetic filter with a fine quartz pulp. A disadvantage of magnetic vacuum filtration with seeding appears to bean increase in cake moisture due to water entrapment in the floes resulting from agglomeration and magnetic attraction.

Jan 1, 1999

By Akira Yazawa, Kazuo Koike, Mitsuhisa Hino

"The vapor pressures of MS (PbS, SnS and Sb2S3) in the molten Cu2S-MS, FeS-MS pseudo-binary and Cu2S-FeS-MS ternary systems were measured by means of a transportation method in the temperature range of 1323 and 1423K to calculate MS activities in the sulfide melts. The activities of MS in these systems show negative deviation from ideal behavior except the FeS binary systems which exhibit nearly ideal behavior in the homogeneous melts. The activities of the Cu2S-FeS pseudobinary system, which is fundamentals of the copper matte, were estimated from the activity values in the ternary systems and exhibit negative deviation from ideality.The distribution behavior of tin between the ·matte and silica saturated fayalite slag was investigated under the controlled partial pressures of S02 at l 523K. It was found that, in general, tin is distributed in the both phase, while tin is concentrated to the slag phase with increasing copper content in the matte. The activity coefficient of SnO in the slag was calculated based on the distribution ratio combined with the activity coefficient in the Cu2S-FeS system.IntroductionThe thermodynamic properties related to the Cu2S-FeS system and the Cu2S-FeS-MS systems (where MS can be PbS, SnS, Sb2S3, As2S3, Bi2S3, etc.) is required to be better understanding of the copper smelting process. However, thermodynamic analysis such as the distribution of impurities among the gas, slag and matte phases is difficult due to lack of thermodynamic data. In this study, the vapor pressures of MS (PbS, SnS and Sb2S3) in the Cu2S-MS, FeS-MS. and Cu2S-FeS-MS systems were measured by a transportation method. The distribution behavior of tin between the matte and silica saturated fayalite slag was also investigated. The results in the present experiments are useful to analyze thermodynamically the behavior of component in the copper matte smelting."

Jan 1, 2000

By R. Boom, C. F. Balentina, J. H. L. Voncken

During vitrification of bottom ash generated from the combustion of municipal solid waste (MSW), a Fe-Cu based alloy phase with great value was formed. In order to find proper commercial use in metallurgical industry, it is necessary to separate Cu and Fe. The present study focuses on the sulfide treatment at temperatures of 1400 – 1500oC, in particular with FeS containing minerals. Various sulfide compounds such as Na2S, Al2S3 and Ni3S2 were added to promote the copper removal. Pyrite and zinc sludge (containing ZnS) as waste streams were studied with specific interests. The results showed that both zinc sludge and pyrite are effective for copper removal with the highest removal efficiency of 95% by using pyrite. The copper content drops from 12 wt% to about 2 wt%. However, it is still difficult to remove copper completely from the alloy in one step, and a multi-step operation is needed.

Jan 1, 2008

By A. L. Davies

The MTDATA computer software package consists of a rigorous implementation of an algorithm for calculating chemical phase equilibria by the technique of Gibbs free energy minimization and a database of the thermochemical properties of common materials, such as slags, mattes, metals, gases and aqueous solutions. We have used MTDATA to contribute to our understanding of the chemical reactions occurring in several specific unit operations of the Kennecott Utah Copper Garfield Smelter. The following two examples illustrate the range of environments to which the method is applicable. Calculation of the liquidus phase relations of the FSF fayalite and FCF calcium ferrite slags helped in the early diagnosis of several operating problems. Calculation of the deportment of fluorine between the FSF offgas and the FSG scrubber liquor helped in the identification of operating conditions under which significant hydrogen fluoride concentrations could be introduced to the contact section of the acid plant. Without the painstaking assessment of solution phase properties undertaken over many years, these calculations would not be possible.

Jan 1, 1999

By Jilai Xue, Jun Zhu, Liang Liu

"Separation removal of fluorite and calcite from scheelite is a difficult technical operation in current industrial practice with a heating process causing large energy consumption and high production costs. In this work, the floatation separation at room temperature were carried out using two types of skarn scheelite ores. The results showed that CaO and Na203 are better than NaOH as a regulator in pH value. In the rough floatation and first cleaning floatation, CaO (500g/t), Na203 (3000g/t) were used as a pH regulator, waterglass (4000g/t) was as a gangue depressant, oleic acid or sodium oleate were used as a collector. The degree of the obtained W03 concentrate was more than 65% (commercial product).IntroductionThe mainly gangue in scheelite are quartz, calcite, barite and some rare metal ores. There are three main types of scheelite for floatation: scheelite--quartz (silicate minerals) type, scheelite-calcite/ fluorite type, scheelite--calcite/fluorite/barite type. Generally speaking, scheelite--quartz type is separated easily, and others are difficult, on the contrary. The last two kinds of scheelite are always called scheelite--calcite/fluorite (barite) type, because there are similar floatation ability and floatation process between them. Scheelite, calcite and fluorite have same cation - Ca2+, it makes them have close floatation property [1]. Separation removal of fluorite and calcite from scheelite is a difficult technical operation in current industrial practice.The traditional separation method is a heating floatation process (Petrov's process) [2]. It can deal with many kinds of scheelite, and can be obtained stable quality ofW03 concentrate. On the other hand Petrov's process causes large energy consumption, high production costs and bad operational environments. Since 1980s, scheelite ambient temperature floatation has become the mainstream of study [3]. Nowadays more and more studies on scheelite floatation focus on complex reagent system [4, 5], rigid operating rules and at the same time development new regulator [1, 5]. Some research show there are new regulators can concentrate scheelite efficiently, but it may cause high costs, potential pollution and difficulty to spread. Oleic acid and sodium oleate used as collector have high adsorption capacity to scheelite, but same to calcite and fluorite[6]. So, it would not get ideal effect for separation of scheelite. In this work, the floatation separation at room temperature were carried out using two kinds of skarn scheelite ores. Calcium oxide and sodium carbonate was used as a pH value regulator, waterglass was used as a depressant and Oleic acid/sodium oleate was used as a collector. The result of experiment showed that the degree of the obtained W03 concentrate was more than 65% by one time ambient temperature roughing floatation, several times ambient temperature cleaning process."

Jan 1, 2014

By K. S. Kumar

FLS miljø, Inc. markets, designs and supplies particulate collection devices for dusts, fumes, and mists; In this paper, the application of both wet and dry electrostatic precipitators (ESPs) in smelting, and roasting plants is discussed.

Jan 1, 1998

By William A. Fuchs

A study of carbonaceous ore at the Santa Fe mine (Corona Gold Inc.) shows that there is no quantitative relationship between organic carbon content and preg rob, although much of this material preg robs. However, there is a relation between K20 and preg rob. Preg rob generally occurs only in those samples with greater than 2% K20. X-ray diffraction and chemical . studies show that the critical factor is the illite content of mixed (possibly interstratified) illite-smectite. Apparently illite, at a certain threshold, "geo-activates" the carbon. The potential for easily monitoring preg rob using a gamma ray spectrometer is discussed.

Jan 1, 1990

By Susumu Nagae, Hajime Ikeda

Recently, a number of mine development projects have been setback by social, economic and, environmental circumstances that had not been seen before. Many of these problems do not always originate from direct mine pollution. Typical examples of these are· conflicts between the exploration company and the local residents, sudden objections just before the development is to begin, and unexpected tightening of environmental regulations. The common background to these problems is expanding global environmental awareness. This includes complex factors ·such as the expansion of exploration to remote regions, the brisk activities of environmental NGOs, the increase of international environmental laws and, governmental policy changes. Today, the range of issues concerning mine development is widening significantly. The participation of local residents arid NGOs in the development planning, together with the company and government, has become essential for smoothly carrying out mine projects and making them more beneficial for stakeholders. Introduction The common image of the environmental problem with respect to mining is direct mine pollution, such as the collapse of tailings dams, pollution from refineries, and acid mine drainage. All over the world, the mining industry has made large investments in capital and technology to solve and prevent mine pollution, and these efforts have been making steady achievements. However in recent years, new cypes of environmental problems which are not originating directly from mine pollution are emerging frequently. Most of the problems are concentrated at the exploration stage to early stage of development, which have less impact on the environment. In the worst case, mining project may be forced to cancel and could cause serious damage to the industry because they could not collect their investment. I would like to take a general view of the examples of new types of trouble, their characters, background, and strategies against these problems.

Jan 1, 2000

By K. R. Robilliard

An outline is given of the problems facing tlile lead and zinc industry from the viewpoint of the range of residues currently produced from electrolytic zinc, blast furnace and other processes. Smelting approaches available using top submerged lancing technology are discussed and analysed. Pilot plant results for a range of lead and zinc-bearing materials are presented.

Jan 1, 1992

By Makiko Takahashi

A tool is being developed to predict and visualize the microstructural evolution of steels during quenching. This tool utilizes experimental data and reference data that are stored in a database to predict the microstructural development. The visualization tool animates qualitative representation of two- dimensional microstructure drawings as well as the quantitative volume fractions of phases present as a function of time. This is achieved by superimposing the Jominy End-Quench test results over the Continuous Cooling Transformation diagram of the alloy. The predicted microstructure is presented through the web browser to maximize the ease of use. In addition, a parallel coordinate system is used to aid in identifying similarities within the data set by presenting the large number of data at a glance. The results for 4140 steel that was quenched in a wide variety of quenchants will be presented to illustrate the prediction and visualization tools. Keywords: Quenching, Microstructure Prediction, Simulation, Data Visualization, Database, Applet, Animation

Jan 1, 2003

By P. Chris Pistorius

"Ilmenite smelting involves partial reduction of iron oxide from a slag consisting mainly of T1O2, T12O3 and FeO, yielding as products iron (with approximately 2% carbon) and titanium slag. Slag purity requirements preclude any fluxing additions, and the aggressive nature of the slag necessitates a furnace freeze lining. Large departures from thermal and chemical equilibrium hold in the smelter, with possible implications for process stability. The slag is approximately 150K. hotter than the metal, which means that the metal temperature is below the slag melting point; this difference in temperature has been shown to lead to formation of a solid TisOs-rich layer between the slag and metal. Recent equilibrium measurements have confirmed that the slag and metal are not in chemical equilibrium either, with significantly more reducing conditions in the metal than in the slag. After solidification, the pseudobrookite slag structure is metastable below approximately 1400K, and may transform upon slight oxidation.IntroductionThe natural mineral ilmenite is the main source of titanium, which is mainly used to produce Ti02-based pigments. Ilmenite has the ideal formula FeTiC>3, but natural minerals can be partially oxidized (to contain some Fe3+), and typically contain MnO and MgO as well, together with associated silicate minerals. Smelting is one of the methods to upgrade ilmenite for subsequent T1O2 pigment production; smelting involves partial reduction of FeO to form metallic iron as a byproduct and titanium slag as the main product. Reduction is typically controlled to yield a slag which contains around 10% FeO, 85% (Ti02+Tij03) and 5% impurity oxides (mainly MnO, AI2O3 and S1O2). An example of a typical average slag composition from reduction of South African ilmenite is shown in Table I. As this indicates, a significant side reaction is reduction of some T1O2 to T12O3. The relative extents of reduction of FeO to Fe and of Ti02 to T12O3 are such that the slag stoichiometry is close to that of the pseudobrookite phase [1]. Pseudobrookite has the structure AB2O5 (where ""A"" and ""B"" are different cation sites); the phase which makes up the bulk of solidified titanium slag has the AB2O5 structure and stoichiometry [2], and can be viewed as a solid solution of FeTi20s, T13O5, ÌçÔÀ2è5, MgTi20s, AI2T1O5 and C^TiOs [1]. This solid-solution phase is referred to as ""pseudobrookite"" or ""M3O5"" in this paper."

Jan 1, 2012

By Wang Shuchan, Zhang Zimu, Zhang Dianhua, Liu Yan, Zhang Ting-an, Zhao Qiuyue, Lv Chao

Rare earth extraction tank has many adverse effects like big floor space and high production accumulation during industrial production. Current researches usually focus on changing the device structure without making a breakthrough towards gravity clarification. This paper attempts to achieve this goal by using both the action of clarification by gravity and clarification by stirring. Because many physical parameters affect the clarification and separation rates, the density, viscosity and surface tension of the two phases were determined at different temperatures and different concentration of aqueous solution. The innovation of this research involves adopting the Karl-Fischer method to investigate water content in oil phase during the stirred separation process. In this paper, the separation effect of different physical parameters was studied and the dimensional equation between water content and the physical parameters was established by combining with the experimental data.

Jan 1, 2014

By Dr. -Ing. Wolfgang Pietsch

Many primary metallurgical wastes are in the sh.-ape of turnings; borings, chips, dusts, and other particuletes. While such. materials can be easily segregated and/or upgraded to yield high quality ?secondary metals with often known composition for easy recirculation into the production? process; their particulate nature results in various problems. Roller presses are used in an ever increasing number for size enlargement and densification of primary particulate metallurgical wastes for secondary metal recycling. The paper will mention the areas of application from A(luminum) to Z(ink), also including Brass; Cast Iron, lead, and Stainless Steel, as well as dusts from all types of melting and ladle furnaces or converters. Typical systems using roller presses for size enlargement. will be discussed.

Jan 1, 1995

By A. J. Paul

Traditionally, 16"/50 caliber projectile shells have been fabricated from forged steel. The Naval Surface Warfare Center (NAVSWC) has determined that cost savings of approximately 60% (-$4.7M/year) as well as improved shell fragmentation can be achieved by casting these shells from austempered ductile iron. One of the technical concerns arising out of this material substitution is the role of the casting process in controlling the quality of the cast shells. Optimizing the process through proper orientation of the mold, placement of chills, superheat, etc., can minimize shrinkage porosity and, consequently, flaw size. For this purpose, the mold filling and subsequent solidification of the projectiles was simulated using a 3-D, fully transient, coupled fluid flow and heat transfer model based on finite differences. Several casting orientations were investigated and the casting parameters were varied to optimize the process and minimize casting defects. A comprehensive software tool, which was developed using state-of- the-art visualization techniques, has been used to analyze the process of casting. Emphasis is placed on the use of this visualization tool as an aid to the foundry engineer for process optimization.

Jan 1, 1992

By Deventer Johanna van

Ore bodies around the world are declining in grade, whilst increasing in complexity. The level of impurities relative to the valuable metal is steadily increasing, posing new challenges to existing operations. Ion exchange is widely used in the hydrometallurgical industry for both primary recovery of metals and the removal of impurities. The superior selectivity of ion exchange resins makes them exceptionally suitable for the removal of target impurities to very low levels, thereby saving operating costs, increasing the value of the final product and significantly improving revenue. The ion exchange process in these applications is very simple, using standard ion exchange equipment and acid regeneration. The process can be fully automated, requiring minimal operator interference and supervision Examples of impurities that are successfully removed via ion exchange include iron, antimony and bismuth from copper electrolyte. In the copper electrolysis process, antimony, bismuth and arsenic tend to form slimes which are dispersed in the electrolyte. These slimes contaminate the cathode and/or decrease the quality of the copper deposition. A special chelating resin was developed to remove antimony and bismuth, while at the same time ensuring minimal chloride leakage to the sulphate matrix. The work is described in more detail in this paper. Ion exchange is also used to remove copper, zinc and nickel from cobalt electrolyte. This paper addresses a few of these examples in more detail.

By M. Radwan

This research reports on the synthesis of advanced silicon-based structural ceramics from mixtures composed of natural sand (Sinai white sand), reclaimed silicon and graphite by the nitriding combustion synthesis method. With pulverized sand (? 40 m), we found that the nitriding combustion can be realized at self-sustaining mode in the SiO2?Si?C system under 3 MPa nitrogen pressure. Depending on the composition of the starting mixtures, single-phase silicon oxynitride (Si2N2O) powder as well as new Si3N4?Si2N2O and Si2N2O?SiC composite powders with controllable chemical compositions were successfully developed. The measured thermograms of various combusted mixtures and the thermodynamic characteristics of possible exothermic reactions in this system were discussed to explain the nitriding combustion behaviour and mechanism. Near-full dense Si2N2O were fabricated from synthesized Si2N2O powder with 5 wt % oxide additive by the spark plasma sintering (SPS) method at 1600 °C. The dense Si2N2O samples had good mechanical properties (18.7 GPa Vickers hardness, 3.3 MPa m1/2 fracture toughness and 363 MPa strength) and excellent chemical and oxidation resistance. The synthesized composite powders were also densified to high densities (> 90 % of theoretical values) by SPS technique. The results obtained in this study can be seen as a new route to prepare important silicon-based structural ceramic powders with various compositions/properties from cheap starting materials which makes them potential for wide range of applications.

Jan 1, 2006

By K. Asokan, K. Subramanian

"Electrowinning of copper by monopolar cells require common anode and cathode busbar and crossbars to connect each electrode to the respective common busbar. On the other hand, the bipolar configuration warrants the end electrodes only to be connected to busbars; there is substantial reduction in copper requirement. In the present work, an electrowinning cell with bipolar electrodes and end electrodes, each having an area of 1000 cm2 was designed and operated. The bipolar electrode is made of mixed metal oxide coated titanium mesh welded to plain titanium sheet. Coated titanium mesh acts as anode and the plain titanium sheet acts as cathode. Environmentally unacceptable lead anode and the recurring loss of lead are done away with. Closer spacing of the electrodes, paves way for the application of higher current density leading to mass transfer enhancement. Performance of bipolar copper electrowinning cell is reported.1. IntroductionThe normally adopted practice in electrowinning of copper is the conventional monopolar configuration. In this practice, the individual electrodes act either as anode or cathode. Hence there is a need to connect every one of the electrodes to the common anode or cathode busbar and crossbars running across the top of the cell are necessary. The common busbar carries very high current which is divided among the individual crossbars and hence has to be thicker in relation to the current load of the cell. The drawback of the need to use common busbars of thicker cross section and the need to have crossbars are obviated in the bipolar configuration."

Jan 1, 2009

By Lijuan Li, Zheng Lu, Xin Xia, Qijie Zhai, Qingchun Li

"Pulsed current and pulsed magnetic field have been applied to the bainite transformation of Cr5 steel. Three groups of experiments were conducted. In the first group, ordinary resistance furnace was used for heat treatment. The Cr5 specimens were rapidly heated up to austenitization temperature 940 °C, held for 20 min, air cooled to bainite transformation temperature 350 °C, held for 10, 20, or 40 min and then air cooled to room temperature. The second and the third group shared the same temperature-time curve with that of the first group, but their heat resources came from the Joule heat produced by pulsed current. 1.5 T pulsed magnetic field was exerted on the third group specimens when they were held at 350 °C, but the second group specimens did not undergo the treatment of magnetic field. It was found that both pulsed current and pulsed magnetic field obviously retarded the bainite transformation. The phenomena were discussed in terms ofliterature results.IntroductionApplying pulsed current and pulsed magnetic field technology are very pronnsmg ways to change the microstructure of materials by affecting the phase transformation process. People had found that pulsed current dramatically influences the behaviors of materials, for example, electromigration effect [l], the solidification of metals and alloys [2, 3], electroplasticity [4, 5], crystallization of amorphous alloys [6], healing of metal materials [7] and so on. As to pulsed magnetic field technology, a lot of effort had been spent on grain refinement in solidification of metals [8, 9], recrystallization of cold-worked metals and alloys [10] and Fe-based alloys solid-state phase transformation [11, 12]. Though application of pulsed current and pulsed magnetic field technology have proliferated in recent years, investigation on their effects on solid/solid phase transformation, especially bainite transformation, is lacking. The aim of this paper is to show the effects of pulsed current treatment (C-T) and the combined treatment of pulsed current and pulsed magnetic field (CM-T) on bainite transformation of commercial Cr5 steel"

Jan 1, 2014

By Milan Lj. Stamatovic

The hydrometallurgical recovery of zinc from recycled blast furnace dust from a steel plant (Smederevo Metallurgical Company - Yugoslavia) was investigated. The dust contained 22% Fe, 17% Zn and 0.2% Pb. X-ray diffractometry showed that the main components were hematite and magnetite, in combination with zinc oxide and a very low content of lead oxide. Individual particles were generally spherical and ranged in size from 10 to 150 microns; 63% were less than 33 microns in diameter. An effective hydrometallurgical approach proved to be by caustic leaching followed by electrowinning. Recovery of zinc in the form of zinc powder was over 90%. This powder can be used for the cementation of impurities in the conventional hydrometallurgical process for zinc production.

Jan 1, 1993