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By Florian Kongoli

Slags and fluxes are important interchangeable dimensions of pyrometallurgical processes. They can increase the efficiency of the smelting, converting and refining processes and improve the quality of the final products. A good slag should have appropriate physicochemical properties such as low liquidus temperature, optimal viscosity, maximum ability to attract undesirable elements, minimum potential of attracting valuable elements, etc .. A good flux, on the other hand, when properly used, can considerably improve the physicochemical properties of the slag since by modifYing its chemical composition it could decrease the liquidus temperature, improve viscosity etc.. Consequently, the choice of a good slag and the corresponding fluxing strategies has become indispensable in most of industrial processes. However, the properties of multi component slags as well as the effect of several fluxes are known only empirically and confusion exists in the literature and in the industrial practice. In today's reality of frequent changes in the composition of raw materials and that of the fluxes themselves, in the existing or new developing technologies, the quantification of the thermophysicochemical properties of multicomponent slags and the effect of fluxes becomes indispensable. This paper reviews some of the work carried out by the author's group during the last ten years on the quantification of the thermophysicochemical properties of multicomponent slags and on the effect of fluxes in several smelting and converting processes in close relation to their individual characteristics. Several examples have been given in order to demonstrate the fact that when taken outside the context some fluxes can become in fact anti-fluxes.

Jan 1, 2003

By I. Gaballah

The electrochemical behavior of a chalcopyrite concentrate having a high pyrite content was studied in HC1 by potentiodynamic, potentiostatic and galvanostatic experiments using a cell having separate anodic and cathodic compartments. Anodic oxidation of chalcopyrite particles was realized both by their contact with the cunent feeder and by reaction with ferric and cupric ions. An increase of current leads to a more selective dissolution of chalcopyrite. Surface passivation was observed after an electrolysis time related to the cell current. Cathodic reduction of chalcopyrite concentrate seems to be more promising. Almost complete conversion of chalcopyrite to a copper sulfide (Cui.8.S) is observed, whereas no reaction of the pyrite was detected. This confirms the possible selective dissolution of copper from the chalcopyrite concentrate. Copper sulfide obtained by cathodic reduction was leached using a cupric chloride solution.

Jan 1, 1994

By E. A. Werner, A. Pichler, A. Spalek, G. Reisner, P. Stiaszny

"Interstitial free (IF) sheet steels are used for complex shaped parts because of their excellent formability. If a deep drawn part is subjected· to a impact deformation at low temperature brittle fracture of the part may occur. This phenomenon\ is called secondary work embrittlement (SWE). One possibility to characterize this material/structural behavior is the drop-weight test. The result of .this .test is a temperature at and below which a crack can initiated in a deep drawn part under the investigated set of parameters. This paper addresses the influence of the preforming process on the sus- . . ceptibili.ty of IF steels to SWE.IntroductionInterstiiial:free (IF-) steels are frequently used in the automotive industry for complex· shaped p·arts because of their excellent deep drawability. The microstructure of the steel consists of a highly ductile ferritic matrix with embedded precipitates of nitrides and/or carbides. Brittle fracture can occur in deep drawn parts, if they are subjected to a high speed deformation at lo""w temperature. This phenomenon is called ~econdary Work gmbrittlement (SWE) [1-11]. Up to now there are no standardized testing procedures available to quantify the sensibility of IF-sheet steel to SWE. Neveitheless, a reasonable testing procedure which allows to quantify the tendency of a predeformed part to SWE is necessary for further material development. A commonly used test method is the drop-weight test performed at low temperatures. In such ·tests a cone-like drop weight expands a deep drawn cylindrical cup [l-3, 6, 8, 9, 11]. From this expansion experiment the temperature is determined at and below which a brittle crack can be initiated in the deep drawn cup under the investigated impact test parameters. The highest measured temperature at which a deep drawn cup fails by brittle fracture is called frack appearances !emperature (CAPT). The lower the value of the CAPT the lower is the sensibility of a deep drawn part of IF-sheet steel to SWE. This paper aims to clarify the role of the preforming process on the impact behavior of an IF steel. For this purpose a numerical analysis of the deep drawing process and cup expansion tests are conducted."

Jan 1, 2000

By K:-I. Rhee

The recovery of tellurium from Te-cement obtained during the processing of copper anode slimes was carried out by a series of hydrometallurgical processes, i.e. leaching Te-cement in NaOH solution, precipitation of impurites with the addition of Na2S followed by direct electrowinning of tellurium in NaOH solution. The optimum conditions for each process were determined and discussed in terms of various parameters associated with each step to maximize the recovery and purity of tellurium. The final purity of tellurium from electrowinning in alkaline solution was found to be more than 99.9 %.

Jan 1, 1997

By Xiaojian Zuo, Yihua Han, Qingguo Xue, Jingsong Wang, Lintao Wang, Rongzong Lan

"Using the facility of reduction experiment, the low temperature reduction pulverization and reduction behavior of sinter in oxygen blast furnace (OBF) were studied. Through analyzing the results, the difference of pulverization and reduction behavior of sinter in OBF and conventional blast furnace (BF) were discussed. Furthermore, the effect laws of reduction temperature and the content of CO and H2 on reduction behavior of sinter were studied. Also the controlling step of iron oxide reduction was discussed. Compared with BF, the low temperature reduction pulverization of sinter became serious at 773 K; reduction rate became faster at 1173 K; reduction time became less and final reduction degree was increased in OBF. With increasing of H2 and CO contents, the reduction of sinter was promoted. The reduction process was controlled by interface chemical reaction at the earlier stage and by interface chemical reaction and internal diffusion at the final stage.IntroductionThe new ironmaking technology of Oxygen Blast Furnace (OBF) is most likely to be used in large-scale application process. The concept relies on the removal of the CO2 contained in the top gas of the blast furnace. Therefore the useful components, i.e. CO+H2, can be recycled back into the furnace and reused as reducing agents. In addition, injecting oxygen (O2) into the furnace instead of preheated air, removes unwanted nitrogen (N2) from the gas. Under the pressure of CO2 emissions in iron and steel making, the growing international shortage of coking coal resources and the rising price of coke, OBF has attracted attentions of both domestic and foreign researchers, because it has so many advantages such as high productivity, high PCI rate, low coke rate, high gas reducing capability and high top gas calorific value, etc [1-7]. As a result of recycling most of the top gas after CO2 removal and injecting oxygen into the furnace, the reduction capacity of blast furnace gas will be increased, so the metallurgical behavior of OBF's iron burden is different from traditional blast furnace. Therefore, it is one of the keys to develop this technology, which studies the metallurgical behavior of sinter in OBF. The purpose of this paper is to study the low temperature reduction pulverization and reduction behavior of sinter at the atmosphere of OBF, which includes the difference of low temperature reduction pulverization and reduction behavior of sinter in oxygen blast furnace and conventional Blast Furnace (BF). It will provide theoretical basis for the development of OBF."

Jan 1, 2012

By Hector Henao

To provide thermodynamic data for converting the nickel matte to liquid nickel, an experimental study was conducted in the phase equilibrium between the Ni-S alloy and the CaO-Ah03 based slag melted in a MgO crucible at 1873 K under controlled Pso2 of 10.1 kPa and pO;, in a range between 2.5x,IO,2 and 10.1 Pa by using CO-C02-S0Z gas mixtures. The content of nickel in the slag at POz of 10.1 Pa, above which solid NiO is expected to precipitate in the equilibrium state, was found to be 4.1 mass% and the contents of sulfur and oxygen in the nickel melt were 0.4 and 0.2 mass%, respectively. It was clarified that increase in the temperature reduces the solubility of nickel in the slag and the contents of sulfur and oxygen in the alloy. The distribution of minor elements such as gold, silver, copper, cobalt, iron, arsenic and antimony between the Ni-S alloy and the CaO-AI20) based slag was also studied. The distribution ratios of iron and cobalt, defined by (%X in slag)/[%X in alloy] where X is the minor element, are larger values than that of nickel, while those of copper, silver and antimony are similar to that of nickel. The distribution ratios of arsenic and gold are lower than that of nickel in the higher range of oxygen partial' pressure.

Jan 1, 2003

By S. Illendula, B. Q. Li, R. A. Mirshams

"An integrated mathematical model is developed to represent the thermomechanical behavior of the materials and microstructure evolution during metal forging. The model development is based on the finite element solution of the thermoviscoplastic deformation of metals coupled with the internal state variable model describing the microstructure evolution involving work hardening, recovery, recrystallization and grain size distribution. The procedures for the integration of the microstructure model into the macro finite element model are described. Computed results for both macro and micro phenomena during metal forging, such thermomechanical deformation such as velocity field and effective strain rate and materials characteristics such as distribution of grain size and recrystallization volume fraction, are presented.1. IntroductionThermomechanical behavior and material microstructural evolution are two critical, interrelated aspects associated with metal workpiece undergoing large plastic deformations such as encountered in forging processes. In much of the modeling work up to date, these two aspects have been addressed separately. Die designs and forging processes are investigated using finite element based thermomechanical models while material dynamics during forging is studied, more often than not, as a separate subject. For many industrial applications, especially those involving novel, light and high strength materials, it is critical to combine these two aspects into a single, integrated model so that materials dynamics and thermomechanical deformation during forging processes can be considered simultaneously [1], thereby providing required information for intelligent process design and optimal process control."

Jan 1, 1998

By Riqing Ye

Laser Engineered Net-shaping (LENS TM) is an emerging manufacturing technique that ensures significant reduction of process time between initial design and final components. The fabrication of fully dense parts with appropriate properties using LENS TM process requires an in-depth understanding of the entire thermal behavior of process. In this paper, the thermal behavior during LENSTM processing of 316 stainless steel was studied both numerically and experimentally. Temperature distribution and gradient in the fabricated 316 stainless steel part were obtained by Finite Element Method (FEM) simulation. The numerical results are in good agreement with the experimental observations. The numerical method may be used to optirnize process parameters and predict the thermal response of LENSTM fabricated components. Key words: Laser Engineered Net-shaping, Thermal Behavior, Finite Element Analysis

Jan 1, 2003

By Teruo Bitoh, Shogo Izumi

"The effect of B203 flux melting on the structure and the soft magnetic properties of the (Feo.1sBo.20Sio.os)96Nb4 bulk metallic glasses prepared by casting has been investigated. The ringshaped bulk specimens were prepared by the B203 flux melting and copper mold casting. It was confirmed that the flux melting promotes the precipitation of the a-Fe(-Si) and Fe2B phases in the central region of the specimens. The ring-shaped bulk specimens show a flat hysteresis curve, indicating a good linear relationship between the magnetic induction and the applied magnetic field. These results show that it is possible to develop a new soft magnetic material that exhibits constant permeability, which is necessary for producing inductors and choke coils.IntroductionSince the success of forming Fe-based bulk metallic glasses (BMGs) with good soft magnetic properties, great attention has been developed to synthesis and properties of the BMGs [l, 2]. The BMGs have high glass-forming ability (GFA) and, therefore, they can be used to prepare bulk amorphous alloys with a thickness of the order of a few millimeters by casting. The soft magnetic properties of Fe-based BMGs are better than those of ordinary amorphous alloys; therefore, these BMGs have wider applications as soft magnetic materials [3-5]. It is often required for soft magnetic materials that the shape of the hysteresis curve is changed according to the demands of applications. For example, materials with ""flat hysteresis curves,"" which means the magnetic flux density (B) and the applied magnetic field (H) show a linear relationship up to rather high magnetic field, are necessary for producing inductors and choke coils. Flat hysteresis curves can be easily achieved by creating an air gap in the magnetic path. However, magnetic flux leakage generated in the air gap inhibits high-density packing of the electronic components. In order to achieve flat hysteresis curves without creating an air gap, Fe-based ordinary amorphous alloys are subjected to crystallization by annealing and transformed into thin surface layers of a-Fe; the crystallization results in the compression of the remained amorphous phase [6]. Another way to achieve flat hysteresis curves is the formation of secondary phase (such as Fe2B) that act as pinning site of magnetic domain wall displacements [7]."

Jan 1, 2013

By Yoichi Takeda

Copper solubility in Si02-CaO-FeOx slag equilibrated with copper matte in 10% S02 atmosphere at 1573K was estimated. Essential parameters are activity coefficients of copper oxide and sulfide, oxygen and sulfur potentials and activity of copper in the slag-matte system. A large number of experiments provide proper parameters to calculate copper solubility in slag. A classical thermodynamic model postulating CUOO.5 and CuSo.; molecules assists in estimating copper solubility in slag. Additions of Si02 and CaO reduce copper solubility almost in any condition. Copper loss, that is function copper solubility and slag volume, in the silica saturated Si02-FeOx binary slag is minimally equilibrated with less than 66% copper matte while copper loss in the 50% FeOx-SiOrCaO ternary slag saturated with 2CaOSi02 is minimally equilibrated with over 66% copper matte. This slag composition has potential for continuous copper converting, direct copper production or high-grade matte production.

Jan 1, 2003

By J. M. Khodadadi

"A computational study of the effect of thermocapillary convection on melting of a droplet under the influence of an incident uniform heat flux is presented. The computations are based on an iterative, finite-volume numerical procedure using primitive dependent variables, whereby the time-dependent continuity, momentum and energy equations in the spherical coordinate system are solved. During the early periods of the melting process, conduction mode of heat transfer is dominant. As the thermocapillary convection is strengthened due to the growth of the melt zone, melting on the side of the droplet is observed to be much faster in comparison to the conduction-only case. Due to the skewedness of the temperature field, a new recirculating vortex is created which promotes melting within the droplet. The effects of the change in the sign of the surface-tension temperature coefficient on the melting pattern are also investigated.1. IntroductionMelting and solidification of materials are important processes which are encountered in nature and numerous industrial applications. Due to the recent upsurge of interest in such processes as spray casting, space radiators, rapid solidification, purification of materials, containerless processing, etc., there is a need to analyze the transport phenomena of melting and solidification in spherical configurations. Specifically, the effect of thermocapillary convection on the melting of metallic droplets has not been addressed at all. Only a few authors have studied the transport phenomena without phase change in spherical droplets. Oliver and DeWitt [l] worked out a series solution for the thermal and surface-tension-driven flow fields for a droplet experiencing an irradiant energy flux in the microgravity environment. Kudo et al. [2] solved the coupled momentum and energy equations numerically for the same problem without dropping the convective terms. Due to the nonexistence of any previous work on transport phenomena during the thermocapillary-assisted melting of metal droplets, this study was initiated to elucidate the features of the phenomenon."

Jan 1, 1999

By Chao Li, Qian Li, Yong-bin Yang, Kai Li, Qiang Xie, Yuan-yuan Zhu, Dong-ye Li, Qi-bing Tan

"The permeability of sintering mix is a vital technological property in sintering process. However, it can only be measured by off-line method on samples picked from the production. In order to acquire the properties of sintering mix accurately, on-line measuring of permeability is urgently required. Based on the reflection characteristics of bed permeability on pipe flowing parameters, a new method is presented in this paper for on-line measuring of sintering mix permeability. The measurement can be performed by blowing gas flow in the bed with the measuring pipe. Measuring results are obtained by picking the data on flowing rate and pressure in the pipe. The function of flowing rate to pressure may be certain for samples with the same permeability. Thus, the permeability was determined by contrasting this function to the result of off-line measuring, and the relative coefficient or R2 value was more than 99%.IntroductionThe permeability of sintering mix is a vital technological property in sintering process, which directly determines production and quality of sinter, or even determines whether the sinter production is carried out smoothly [1,3].The permeability have more obvious influence on vertical sintering speed, which is mainly related to air quantity passing through material bed. Under certain inducing capacity and negative pressure, the vertical sintering speed mainly depends on the permeability of sintering mix. Low permeability may make burning through point of sintering move back, and the sinter mix cannot be burnt through. High permeability may make burning through point of sintering move forward, improving production efficiency by increasing the speed of sintering machine [4] Good permeability means a small resistance of fan ,reduction of negative pressure of sintering machine, and full contact between air and sulfide, which can strengthen physical-chemical reaction during sintering process and increase desulphurization rate. In gas well through material layer process, gas-solid desulfurization reaction and gas-solid-liquid heat exchange are completed and hot gas through the combustion zone supplies the sintering process with heat. Finally uniform sintering of the material layer in height and width direction is achieved [5] While high permeability index leads to weak sinter strength, fast sintering speed, short residence time of high temperature region and little liquid phase. Moreover, liquid phase in the fast cooling process is too late to fully crystallize but forming glass phase which is harmful to sinter strength as well. Bad permeability means a big fan resistance and increase of negative pressure of sintering machine, which make the air pass through material layer difficultly. When air and mix contact difficultly, removal of sulfide reduces so that desulfurization is incomplete. Meanwhile, low caking efficiency, slow sintering speed and easily burnt sinter , reduce sinter output. Therefore appropriate permeability of sintering mix is the premise of stable burning through point and satisfactory sinter output and quality."

Jan 1, 2013

By D. E. Larson

The U. S. Bureau of Mines has developed a image analysis methodology to correlate the energy consumed during the grinding of an ore to the mineral liberation achieved. Energy consumption values are obtained using a laboratory-scale ball mill equipped with a torque sensor, and an automated image analyzer is used to determine the liberation present in ground products. By combining liberation information with energy consumption data an appraisal can be made of the energy required to liberate the mineral(s) of interest. Results of tests performed on a complex sulfide material determined the effects of grind duration on the liberation achieved and the energy efficiency.

Jan 1, 1995

By Yongzhong Xiao, Tiejun Chun, Jian Pan, Deqing Zhu

"An innovative process of reverse floatation-direct reduction-low intensity magnetic separation was developed to effectively beneficiate the superfine run-of-mine (ROM) ore mined from Hunan Province, China. Mineralogy was measured that the ROM ore is of superfine low grade hematite ore type, assaying 27.2wt%Fetotal and with main valuable minerals of hematite occurring at size between 3 to 5µm. The upgrading results show that the final iron concentrate, assaying 88.3wt%Fe total and 94.5% metallization degree was obtained at an overall iron recovery of 69.9% under the following conditions: rough concentration by grinding of ROM up to 88.7% passing 0.074 mm and reverse flotation at pH=9.4, 100 g/t starch and 200 g/t dodecylamine (DDA), and coal reducing the rough concentrate pellets containing 12% calcium containing complex additive at 1200 oC for 120 min, and finally magnetic separation of the reduced pellets by grinding up to 89.2% passing 0.043 mm at 0.08 T field intensity.IntroductionWith the rapid development of iron and steel industry in China, there has been a soaring demand for iron ores in the past decade. The imports of iron ores have increased from 148 million ton in 2003 to 628 million ton in 2009 [1]. Iron making industries increasingly demand for high grade raw materials to improve product quality and reduce operation cost. However, availability of high grade natural ores is limited and enrichment of lower grade ores is necessary to meet the demand. Therefore, large quantities of superfine low grade iron resources are necessary to utilize in China at the moment."

Jan 1, 2011

By M. Misra

Acid mine drainage from reactive sulfide tailings is a major environmental concern facing the mining and mineral industries. A preventive technique to control acid mine drainage by agglomeration and encapsulation process is presented in this paper. The reactive tailings are agglomerated using Portland cement type I1 as binder. The cold bonded agglomerates after specified curing period are, strong and resistance to weathering. The leaching and weathering experiments have shown that a significant reduction in the concentration of dissolved metals can be observed with the agglomerates as compared to as- received tailings. Addition of small amount of sodium silicate during agglomeration increases the strength and develop good resistance to weathering by forming a glassy coating and elongated crystals within the agglomerates.

Jan 1, 1993

By Jorge A. S. Tenorio, Chuanwei Zhuo, Joner O. Alves, Yiannis A. Levendis

"The ever increasing number of automobiles and the consequential increase in consumption of tires have generated a pressing environmental issue, concerning the disposal of unserviceable tires. The worldwide disposed of waste tires is approximately 1 billion units per year and this amount is expected to increase by 2% each year. This work presents a microstructural characterization of nanomaterials synthesized in a catalyst system from the effluent of burning waste tire chips in a horizontal two-stage laminar-flow furnace. Controlled combustion of waste tire chips took place at temperatures of 900 or 1000 °C, and stainless steel meshes were used to synthesize the nanomaterials at 1000°C. Produced materials were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The catalyst meshes were covered by materials with diameters of 20 to 200 nm and lengths of about 40 µm. They possessed structures similar to those of carbon nanotubes.IntroductionThe motor vehicles on the road have been increasing annually. World motor vehicle production in 2009 approached 62 million units. Consequently, the consumption of tires has also been on the rise; about 1.4 billion units were produced around the world in 2007 [l]. The disposal of scrap tires is a serious environmental problem. The worldwide disposed of waste tires is almost 1 billion units per year with an expected increase of around 2% each year. However, less than 7% of produced waste tires are recycled (excluding reuse, retreading or incineration). The waste rubber tires are a thermoset polymer, which cannot be reprocessed like thermoplastics polymers, therefore the recycling of this material requires special techniques that demand big investments [2, 3].A solution to the disposal of waste tires is the sequential pyrolysis/combustion process. Past research showed that waste tires are an attractive potential fuel due the high heating value (29-3 7 MJ/kg), which is comparable, or even higher to those of typical bituminous coals [ 4, 5]. Pyrolysis is a process wherein the material is thermally decomposed at elevated temperatures at the absence of an oxidizing gas. Combustion is characterized by the addition of the oxidizing gases during the process. Several studies indicate that the pyrolysis and combustion processes for the tires treatment have a great energy conversion potential [4, 5, 6]."

Jan 1, 2011

By Bemd. E. Langner

At Norddeutsche AfFmerie the CollaMat is an important instrument for controlling the activity of glue in copper electrolyte. Thanks to on-line measuring of the glue activity appropriate action can to taken in the event of sudden changes, such as an intemption in the glue supply, as well as long-term trends, such as continuously decreasing glue activity over days or weeks. Laboratory tests on the dependence of glue degradation on temperature have shown that relatively small increases in temperature of only 3OC cause the half change value of the glue degradation to reduce by 25 %. It is a similar picture with the sulphuric acid concentration in electrolyte. An increase in the acid concentration from 160 g/l to 200 g/l can - depending on the temperature - likewise result in a decrease in the half change value of up to 25 %.

Jan 1, 1995

By S. P. Mathew

The ISASMELT Lead Process is a continuous two stage process for the production of crude lead from concentrate. It is based on the use of a top entry submerged Sirosmelt lance to produce turbulent baths in which high intensity smelting or reduction reactions can occur. The process involves oxidizing the concentrates in the first stage to produce a high lead slag. This slag is tapped continuously and transferred down a launder to a second furnace where it is reduced with coal. Crude lead and discard slag are tapped continuously from this furnace through a single taphole and separated in a conventional forehearth. Process and engineering design work for a commercial scale Lead ISASKELT plant designed to produce 60000 tpa crude lead has been completed. This plant is planned to be operational in 1991.

Jan 1, 1990

By Roberto Parra

The classic criteria of the preparation of the charge for the smelting of copper concentrates in at flash furnace considers the mass and energy balance from the chemical and mineralogy composition of the concentrates. The operation parameters fixed with this method don't assure the stability of the operation and the critical problems of the slag quality and dust formation occurs very often. This paper presents the results of a laboratory test that allows the prediction of the behavior of concentrates blends in the view of the minimization of the dust formation and the magnetite control in the slag. The combustion of different copper concentrates and blends were done in a drop tube furnace The results show that the magnetite and dust formation don't have a linear behavior with the weight proportion of the blend and some optimal blends of 2 or 3 types of concentrates can be identified. From the reasonable hypothesis that the qualitative behavior of blends in the drop tube represents the real behavior in the burner, the preparation of the charge with this approach could help to solve those operational problems.

Jan 1, 2003

By M. Soltanieh

The liquidus surface? and tie-lines in the nickel-cobalt-sulphur ternary system have been determined between 1<273-1573 K. The experiments were conducted by equlibrating the liquid sulphide with the metallic alloy phase. The liquid sulphide phase was sampled and chemically analyzed. The alloy was analyzed by electrol} microprobe. Combining the present results with the.avai1abl~ literature data, the thermodynamic properties of this system were calculated.

Jan 1, 1998