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By Youn-Bae Kang

Evaporation mechanism of S from liquid Fe–C–S alloys at 1873 K was proposed by analyzing available experimental data. It has been known that increasing C content in liquid alloy increases activity coefficient of S ðfSÞ, and it could raise driving force for the evaporation reaction S = S(g). However, experimental data of the evaporation of S in the Fe–C–S alloys could not be accounted for only by considering the increases of fS. In the present study, formation of carbosulfides, CS(g) and CS2(g), was additionally taken into account in order to explain role of C for the accelerated S evaporation. Surface adsorption of S was also taken into account, which retards the evaporation rate of S. An evaporation model equation was formulated. It can be applied to calculate the evaporation rate of S over wider C content (from zero to its saturation to liquid alloy).

By Jim Sundal

Primary steel manufacturers using electric arc furnaces generate one of the largest hazardous waste streams nationwide. The waste stream, known as electric arc furnace dust, is a listed hazardous waste with the designation K061. Oregon Steel Mills, Inc., (OSM) of Portland, Oregon, has implemented a process known as Glassificationn, which uses KO61 as an ingredient in an onsite recycling process. Because OSM was able to demonstrate that the Glassificationm recycling process beneficially uses all toxic constituents in the electric arc furnace dust and that the recycling process produces marketable products, the process is not subject to Resource Conservation and Recovery Act (RCRA) permit requirements. The marketable products manufactured using Glassificationn include roofing granules, ceramic glazes and colorants, abrasive blasting media and, more recently, synthetic slag fluidizers. The purpose of this paper is to identify the regulatory issues for recycling hazardous waste and demonstrate that OSM glass frit is effective as a slag fluidizer in primary steel manufacturing.

Jan 1, 1994

By Nathalie Neveux

For the first time, dehydrated ferrous sulfate was successfully used for the dry synthesis of potassium ferrate. In addition, ferrate ion is stabilized as a solid solution where hexavalent iron is partially substituted by S(V1) leading to a sulfato-ferrate having the following formula K2(Fe,S)04. This substance has an efficient life time of about six months. Ferrate ion is a powerful oxidant ( EO = 2.2V ), a bactericidal agent and possesses coagulant, flocculant properties. Its reduction generates nascent oxygen, hydroxyl groups and Fe(OH)3. Alkali metal ferrate is probably the future global agent for water treatment. Applications of this material in the field of urban and industrial effluents treatment have been investigated. Heavy metals cations such as Cu, Cd, Mn, Ni, Pb, Zn, ... were successfully removed. The results of sulfato-ferrate use for cyanide destruction, decrease in COD, soil, discoloration of pulp and paper effluents will be summarized.

Jan 1, 1999

By Jonkion M. Font, Ramana G. Reddy

A thermodynamic model for a priori predictions of arsenic and antimony impurity capacity in Ni-Cu mattes and slags was developed based on the Reddy-Blander (RB) capacity model. The As and Sb capacities were calculated a-priori considering the RB capacity model in Ni-Cu mattes and FeO-FeO1.5-MgO-CuO0.5-NiO-SiO2 slag at 1573 K and 0.1 to 1 atm partial pressure of SO2. The results showed an excellent agreement between the model calculated and experimental data of arsenic and antimony capacities between the mattes and slag. The impurity capacity model developed here, can be extended for prediction of impurity capacities in multi-component base metal slags and base metal mattes. Such a priori predictions of impurity capacities can lead to develop or improve the efficiency of impurity removal from the base metal smelting, converting and refining processes.

Jan 1, 2014

By Anxiang Wang, Kunhua Wu, Yifu Li, Junjie Xu, Yongnian Dai, Bin Yang, Lingxin Kong

In this study, the saturated vapor pressures of tin (Sn) and antimony (Sb), the separation coefficient and the vapor-liquid phase equilibrium of Sn-Sb alloy were theoretically analyzed, which demonstrate that it is possible to separate Sn and Sb by vacuum distillation. The process parameters of vacuum distillation, including the distillation temperature, distillation time and alloy mass (thickness of raw materials) on the direct yield of Sn and the content of Sn in liquid phase were investigated by using single factor experiments. The preliminary results show that the direct yield and the content of Sn are 98.77 wt.% and 96.01% with the optimized distillation conditions of a distillation temperature of 1473 K, a distillation t ime for 45 min and a Sn-Sb alloy mass of 125 g ( thickness o f 8 mm). The distillation parameters in the study provide effective and convenient conditions on separation of Sn-Sb alloy.

Jan 1, 2016

By Fangqing Yin, Qingyu Deng, Zhengfeng Qu, Mengjun Hu, Meilong Hu

Titanium bearing blast furnace slag, which contains 20%-30% TiO2, is a valuable secondary titanium resource. Based on the thermodynamics calculation effect of the temperature on the reduction of the slag in vacuum were studied at certain vacuum degrees. The results show that magnesium vapor and silicon monoxide vapor can be obtained at the condition of high temperature and low pressure. The purity of TiC increases with temperature increasing. When the temperature arrives at 1623K TiC can be obtained besides the reductant carbon. XRD result of the powder collected from the furnace cover show that magnesium and silicon in the titanium bearing BF slag leave the slag system during carbothermal reduction in vacuum. From the above it can be concluded that TiC can be obtained from the titanium bearing BF slag and silicon and titanium in the slag can be separated by carbothermal reduction in vacuum and acid leaching.

Jan 1, 2016

By Elli Miettinen

In Copper Flash Smelting operation disturbances may lead into dust build-up in the gas train and off-gas handling system causing reduced heat recovery efficiency and process availability. Flue dust of a Copper Flash Smelting process heat recovery boiler has been characterized and its thermal conductivity and diffusivity have been determined. Dust accretions consist of several layers possessing varying particle sizes, densities, and thermal properties, with the binding phase usually being sulphate. All the dusts can be regarded as effective thermal insulators with thermal conductivity values of less than 2 W/mK and thermal diffusivity values of less than 0.005 cm2/s. Porosity can be regarded as a fairly good indicator of the thermal transport efficiency of these types of materials, but the material microstructure must also be considered. The results can be used in the dimensioning of metallurgical heat recovery boilers and they also provide accurate input data for process models.

Jan 1, 2009

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 Jiang Diao, Xuan Liu, Tao Zhang, Bing Xie

In the present study, the oxidation process of vanadium and chromium bearing hot metal was investigated by using CaO-FetO-SiO2 slags at 1653K in MoSi2 furnace. The results indicated that both the vanadium distribution LV and chromium distribution LCr were of the orders of 2.2~2.4 with the basicity range of 1.32~1.78 and FeO weight percent range of 28%~45%. Both LV and LCr decreased with increasing basicity and decreasing FeO weight percent. The phosphorus distribution LP was of the order of 1.34~1.56. However, LP increased with increasing basicity and decreasing FeO weight percent. The oxidation ratio values of V and Cr in hot metal were above 84% and the values of P were nearly 50%. In other words, it means the addition of CaO in vanadium slag provided a certain ability of dephosphorization along with keeping high oxidation ratios of V and Cr.

Jan 1, 2015

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 S. Yuan

Oxygen ion conducting yttria-stabilized zirconia (YSZ) tube was used to remove oxygen from molten Cu at 1373K. Outer surface of the tube was in contact with the melt and the inner surface containing a thin layer of porous Ni-ZrO2 cermet electrode was in contact with a reducing gas. The migration of oxygen species (O2-) from the Cu melt through the YSZ tube is accompanied by an equal and opposite flux of electrons maintaining electroneutrality. Without applying an external EMF, the fluxes are maximized by short circuiting the melt with the cermet electrode. For efficient oxygen removal, the YSZ tube must be thin, contact resistances should be negligible, and the electrodes must be porous and cover the entire electrolyte surface for charge transfer. This refining process is environmentally sound, can use reducing gases such as H2, CH4 and CO without running the risk of increasing H or C content of the melt.

Jan 1, 1993

By E. A. Trillo, L. E. Murr, R. D. Flores, J. C. McClure, B. M. Nowak

Complex vortex and swirl-like solid-state flow phenomena have been observed in the residual microstructures characterizing the friction-stir welding (FSW) of copper to 6061 aluminum; 2024 aluminum to 6061aluminum,2024 aluminum to 1100 aluminum, 2024 aluminum to 7039 aluminum and 2024 aluminum to 2195 aluminum. These flow phenomena are characterized by intercalation lamellae composed of dynamically recrystallized grain structures of the dissimilar metals which provide a super-plastic-like mechanism for the FSW flow in the solid state; there is no melting and temperatures at the weld center do not exceed about 0.8 TM (where TM is the absolute melting temperature (K)). In experiments to be described and illustrated, optical or light metallography (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques are utilized in examining residual FSW microstructures corresponding to tool rotation (stirring) speeds ranging from 400 to 1200 rpm, and traverse (or actual welding) speeds of 1 to 2 mrn/s.

Jan 1, 1999

By J. W. A. Morris

To investigate the use of centrifugal fields in fused salt electrowinning cells, a high temperature rig has been designed, constructed and commissioned. Initially, the cell has been applied to the fused salt electrowinning of zinc. Current efficiencies of 93% have been obtained for inter electrode gaps as small as 8mm for 70mm diameter electrodes rotating at 100rpm. The construction of a semi-rigorous physical model has shown the potential exists to extend the use of centrifugal fields to the electrowinning of light metals.

Jan 1, 1994

By A. C. Neiva

An energy-dispersive x-ray fluorescence spectrometer was assembled with the aim of analysing alloys and corrosion products of artistic, ethnological and archaeological pieces. The spectrometer is semiportable and consists basically of an 60kV/1.5mA X-ray tube with W anode and a Si-drift X-ray detector with Peltier cooling, with no need of liquid nitrogen. It was used for the analysis of the alloys and occasional corrosion products of several metallic pre-Hispanic pieces of the Museum of Ethnology and Archaeology of the University of São Paulo. Special care was taken to account for the contribution of spurious radiation from both the Pb primary collimator and the Zr detector collimator. The main components of most alloys were Au, Ag and Cu, but Pb, Ca, Fe and other elements were also identified. The characterization of the alloys and corrosion products is important for the subsequent conservation of the collection.

Jan 1, 2006

Gas-liquid contacting in the packed bed is a common operation in metallurgical reactors. Research has shown that, unlike wetting flow, non-wetting liquid flows in the form of discrete droplets or rivulets. Thus, modeling of the liquid phase as a continuum is in contradiction to the observations. Also, for the non-wetting case, continuum models have failed to describe liquid flow path when the liquid source is a point source. The aim of the current work is to put forward a combined Lagrangian-Eulerian approach to model the liquid and gas flow in the packed bed. Liquid is assumed discrete and modeled using a force balance approach. Gas is assumed to be interpenetrating continua and modeled using k-emodel for turbulent flow. Structured packing is assumed and x- ray imaging technique is used to visualize liquid flow lines in the bed. Simulation results for liquid flow path compared with the experiments.

Jan 1, 2006

By Y. Y. Sheng

Plume flows created by gas injection into liquid metals have been studied extensively, however the dynamics of bubbles within the plume have not received adequate attention, particularly for large, irregular bubbles, characteristic of the processing of liquid metals. The present model uses a combined Eulerian-Lagrangian approach in which an estimated void fraction distribution is used to calculate the liquid flow field with a conventional Eulerian scheme. The trajectories of bubbles are then computed in a Lagrangian manner using the estimated flow field, and experimentally measured information on bubble drag coefficients', lateral migration due to lateral lift forces and interaction with turbulent eddies, and variation in bubble size due to break-up. Turbulence in the two-phase zone is modeled with a modified k-e model with extra source terms to account for the second phase which have been recently determined by the present authors. The computed void fraction and turbulent liquid flow field distributions are in good agreement with experimental measurements.

Jan 1, 1993

By R. G. Reddy

The oxidation kinetics of A13Ti intermetallics have been studied at the temperature range of 850°C to 100O0C in pure dry oxygen. The oxygen diffusion rates were investigated using TGA method. Parabolic rate constants were calculated. The oxidation scales were analyzed using SEM, EDS and X-ray diffraction. A continuous A120, scales with a little TiO2(rutile) were formed on the intermetallic surface. The A13Ti intermetallic exhibited excellent oxidation resistance among the Ti-Al base intermetallics.

Jan 1, 1997

By A. V. Tarasov

Investigations of thermodynamic properties of Cu-Ni and Cu-Ni-S systems and mattes have been conducted with the aid of a MC-1301 mass-spectrometer designed for studies-of processes of vapor formation of hardly volatile substances. The instrument comprised a combination of an evaporator of Knudsen chamber type with a mass-spectrometer for analysis of the vapor phase, In the process of studies of molten Cu-Ni-S systems and commercial-grade mattes within a temperature interval of 1400-1800 K the partial pressure of sulfur was measured by means of complete isothermal evaporation and the partial pressure of copper and nickel by comparison of ionic currents. The partial pressure values of the components above the molten Cu-Ni-S were used for calculation of activities of the respective components in the melt. The copper and nickel activity data obtained was used for assessing the amount of dissolved losses of these metals in autogenous smelting slags.

Jan 1, 2003

By A. V. Tarasov

Investigations of thermodynamic properties of Cu-Ni and Cu-Ni-S systems and mattes have been conducted with the aid of a MC-130 I mass-spectrometer designed for studies of processes of vapor formation of hardly volatile substances. The instrument comprised a combination of an evaporator of Knudsen chamber type with a mass-spectrometer for analysis of the vapor phase. In the process of studies of molten Cu-Ni-S systems and commercial-grade mattes within a temperature interval of 1400-1800 K the partial pressure of sulfur was measured by means of complete isothermal evaporation and the partial pressure of copper and nickel by comparison of ionic currents. The partial pressure values of the components above the molten Cu-Ni-S were used for calculation of activities of the respective components in the melt. The copper and nickel activity data obtained was used for assessing the amount of dissolved losses of these metals in autogenous smelting slags.

Jan 1, 2003

By R. G. Reddy

The effect of solid particles on viscosity behavior of Na2O-O-B2O3-SiO2 melts of composition XSio2/XNa2o =0.5 and in the temperature range of 900- 1150 K was studied. Samples were analyzed by X-ray diffraction and optical microscopy. The results showed that a crystalline phase (NaBO2) was formed and its amount increases with decrease in X,, from 0.50 to 0.25. The experimental viscosity values were compared with the predicted values using our viscosity model developed earlier. At low temperatures, for low content of B2O3 , the experimental values exhibits a large deviation from the predicted values. It was concluded that the deviation was due to the formation of solid particles in the molten slags. The existence of these solid particles increased the viscosity values significantly. A new viscosity model was developed to include the effect of solid particles.

Jan 1, 1993