Search Documents

By S. Yokoya

With increasing requirement of steel productivity and quality in continuous casting in the conventional casting system using an immersion nozzle, it is very difficult to establish a reasonable molten flow pattern. In order to overcome this difficulty, we propose a new method of imparting swirling motion onto the flow in the immersion nozzle and to control the flow pattern in the mold. Following results have been obtained during the studies. For the case of slab continuous casting mold: High amplitudes of oscillation with a period of 10 to 15 seconds are observed in the outlet flow of the immersion nozzle and meniscus flow in the conventional casting system, while these phenomena are remarkably suppressed using swirling motion in the immersion nozzle, which leads to very calm and uniform flow pattern at the outlets of the immersion nozzle, in the mold and on the meniscus in the mold; For the case of billet continuous casting mold: (1) heat and mass transfer near the meniscus can be remarkably activated compared with a conventional straight type immersion nozzle without swirl, and (2) Quite different mold flow patterns are observed between the divergent and straight immersion nozzles. Heat and mass transport in the mold using the divergent nozzle is much more reasonable compared to that of straight nozzle. The findings, mentioned above, are very useful to control the flow pattern in the slab, and billet continuous casters. Such effectiveness of swirling flow in the SEN on the mold flow has been put into practical use. As a result, remarkable progress on the quality and production of continuous casting products has been observed in practical application.

Jan 1, 2006

By Victor Bredykhin

The report is devoted to the investigation and improvement of processes taking place at contact of large quantities of water insoluble liquid and particles of solid phase in a pulp. Theoretical analysis and simulation of acting conditions have allowed to determine that after attaching of oleophilic particles on the «water-reagent» separation surface the break of a formed complex is taking place according to the reagent volume and for oleophobic minerals along the «solid-reagent» separation surface. As a result particles are selectively treated if the magnitude of the reagent adhesion to the surface of solid phase in water is great. The results of dispersion are influenced significantly by availability of sharp edges on the surface of real particles. They keep tree phase perimeter of moistening. It is possible to fix reagent in the form of lens whose contact angle is significantly smaller in comparison to the thermodynamic angle. In adhesion dispersion the reduction of reagent volume, covering the equal area of particles surface is possible when the reagent is in a pulp in the form of thin films on the «water-gas» separation border. The process is tested in laboratory conditions as well as at pilot concentrating mills in flotation of sulfide ores, non-ferrous metals (copper-molybdenum ore), native sulfur and coal.

Jan 1, 2006

By Liu Chunpeng

The new technological process developed is by means of thermal plasma arc smelting to obtain high grade Ni matte directly from Ni-Cu concentrates containing 6-7% nickel and 3-8% sulfur. In comparising with conventional smelting and converting processes the plasma arc smelting process has many advantages over conventional processes, such as lower energy consumption, lower capital investment and free from SO, pollution by transforming the sulfides into elemental sulfur with microwave irradiation under controlled oxygen potential, moreover, the process is simple and easily controlled due to less magnetite troubles in the operation. Therefore, this new technological process can be used as an alternative way to conventional process for Ni-Cu concentrate smelting. The main economical technical index is summarized in Tabal 1. Table 1 Main Ecnomic-technical Index

Jan 1, 1993

By N. El-Kaddah, V. L. Acoff, M. Arenas

"Control of the weld penetration, weld pool shape and temperature field in arc welding is critical to achieve the desired microstructure and mechanical properties in the resultant welds. This is particularly important in welding gamma titanium aluminides (y-TiAl) where the weld pool is relatively shallow and the temperature gradient in the heat-affected zone is quite steep. This paper investigates theoretically and experimentally the evolution of the shape of the weld pool for stationary gas tungsten arc welds in y-TiAl alloys. A mathematical model has been developed for predicting the electric current flow, the resultant electromagnetic forces in the metal, and the transient development of the temperature and velocity fields in the molten pool generated by a spatially variable heat flux at the arc-striking zone. The governing equations were solved numerically using the control volume technique. Welding experiments were carried out to determine the shape of the weld pool and the extent of the heat affected zone at different welding times for model validation. The numerical predictions were found to be in reasonable agreement with measurements. It is suggested that the model presented in this paper is likely to provide the information needed for predicting the microstructure and mechanical properties of y-TiAl welds. IntroductionIn recent years, there has been considerable interest in the welding of gamma titanium aluminides as a means of manufacturing high-temperature, high-performance components for turbine and automobile engines. These alloys are highly reactive, and must be welded in vacuum or inert gas atmosphere, rendering electron beam, and inert gas tungsten arc welding (GTA) to be the only suitable welding techniques for joining these materials [1-3]. The GTA welding is especially attractive because of its flexibility and relative cost-effectiveness. However, previous studies on the weldability and weld properties of these alloys using this process revealed a decrease in the mechanical properties in the fusion zone [4]. This is generally attributed to the change of the original duplex structure to a dendritic structure amplified by the shallowness of weld spot. Quantifying the effect of arc operating parameters on the geometry and temperature profile of the welding pool prior cooling is the first step for controlling the fusion zone microstructure and mechanical properties."

Jan 1, 1999

By A. J. Davidson

A novel sensor is described for the measurement of the copper content of copper matte. Due to the high copper concentrations found in matte, potentiometric sensors are not sufficiently sensitive. A highly sensitive sensor has been developed based on a modification of the amperometric technique using a copper ion conductor, Cusicon. The results correlate closely with the theoretical predictions.

Jan 1, 1998

By Patrick R. Taylor

Thermal plasma technology has a wide range of applications in extractive and process metallurgy. Beneficiation of complex ores, oxide reduction, melting/remelting of refractory metals and scrap, and the recovery of precious metals from waste products are some examples of potential uses for plasma technology. The highly concentrated enthalpy provided by plasma torches is a cleaner energy source and may give higher processing rates per reactor volume than conventional technologies. Some of the other advantages may be: controlled furnace atmosphere, ability to treat fine feed materials and rapid quenching. A review of some of the uses for plasma processing in non-ferrous process and extractive metallurgy is presented.

Jan 1, 1993

By B. Sereda

As it is known the creation and development of new titanic alloys has been problematic up to now. They can be used in aircraft and vehicle construction, shipbuilding and as materials for keeping static loadings in high-temperature environments. In this work the synthesis of various titan aluminides is investigated. Mathematical model of structurization process was done. On the base of retrieved model the mechanisms of structurization in systems Ti + Al and Ti + 3Al was determined. Experimental researches were done at two different modes: burning and thermal spontaneous ignition. The method of retrieving compacted products combusted in SHS conditions (SHS-compacting) was used to gain these intermetallic compounds. The physical and thermal characteristics of technological process and their influence on structurization, homogeneity of structure and porosity of titan aluminides have been simulated and researched. It is established that the SHS-compactizing technology is fully capable of supervising the process of structurizations with the whole complex of advantages and can be applied for receiving qualitative titan aluminides with the set of chemical-physical properties.

Jan 1, 2010

New method for processing of copper and nickel production feed has been developed and tested at pilot unit having 10 t/hr capacity. The process allows single-stage treatment of ore feed including that with high magnesium oxide content and resulting in the production of rich matte, high-grade matte, or moralised alloy for further leaching, as well as dump slag and off-gasses suitable for production of elemental sulphur, liquid sulphur dioxide, or sulphuric acid. Tests results and principal technical and economical parameters are presented.

Jan 1, 2006

By Katsukiyo Marukawa, Manabu Iguchi, Sigeta Hara, Shinichiro Yokoya, Sigeo Takagi

"A numerical analysis and water model study of the mold region of a continuous casting apparatus was performed with a novel injection concept using swirling flow in the pouring tube, to control the heat and mass transfer in the continuous casting mold.As a result, the following results were found:1) By changing swirl strength, it is easy to control the flow pattern as well as the direction of the flow.2) Uniform velocity distribution can be obtained within a very short distance from the outlet of the nozzle.3) Heat and mass transfer near the meniscus can be remarkably activated compared with a conventional straight type immersion nozzle without swirl.4) Swirl helps the superheat in the melt dissipate.S) Penetration depth of nozzle outlet flow is decreased remarkably by the application of swirling.6) For the case without swirl, the peak of the flow moves near the mold-wall with flowing down from the outlet of the nozzle due to the Coanda-effect. On the other hand, peak of the flow moves near the mold axis with flowing down from the nozzle-outlet within considerable short distance, namely axi-symmetric velocity distribution can be obtained within very short distance from the nozzle-outlet.Those findings mentioned above are very useful to control the flow pattern in the billet and bloom continuous casters."

Jan 1, 2001

By Qin Hua, Xiangru Chen, Qijie Zhai, Yongsheng Yan, Liang Chang

"In this paper, pure bainite ductile iron and their alloying form of 0.2wt% niobium were prepared by a controlled cooling heat-treatment. The effect of niobium alloying on the microstructure, hardness and impact toughness of bainite ductile iron was studied. The results show that adding niobium effectively improves the hardness and toughness of bainite ductile iron. The hardness and the impact toughness of niobium-alloyed bainite ductile iron were investigated by varying the temperature at which samples were fed to the incubator.IntroductionThere are two essential methods to prepare the bainite ductile iron: isothermal quenching [I-31, and alloying [4• 51• Isothermal quenching process is very time and energy consumable, concerned as a high cost technique for mass production. Besides, there are certain limitations on the size and shape of castings in this process. In addition, it potentially harms the environment. As for the alloying, Ni, Mo, and Cu have to be utilized to obtain bainite. However, the large demand and high cost of Ni makes it not feasible in practice.It is well known that niobium can promote the formation of carbon compound, and improves the stability ofundercooled austenite, which is preferred to the increase of the hardenability. Previous studies showed that niobium could refine the grain and improve the mechanical properties of gray cast iron [6-81 • Therefore, in the present work, the effects of niobium and the temperature at which samples were fed to the incubator on the microstructures and properties of niobium alloyed bainite ductile iron were investigated."

Jan 1, 2014

By T. Taniguchi

The existing Mitsubishi Process line at Naoshima Smelter and Refinery has been operating successfully since 1991, and its present production capacity is 270,000tpy of copper. Furnace relining works have been carried out every two years to coincide with the compulsory bi-yearly boiler inspection, but the next target is to extend the furnace refractory life to four years, while still undergoing the mandatory boiler inspection every two years. Although the damage of hearth bricks beneath lances in the Smelting furnace was a matter of concern, it was reduced by controlling gas velocity and evening solid distribution to each lance. The life of bath level bricks in the Converting furnace was also a concern, but four-years continuous use of the bricks was achieved in the course of the last two campaigns. Several other improvements were also carried out to the cooling systems during the shutdown in 2005 to ensure longer campaign life. This paper summarizes recent improvements implemented to enhance the advantages of the Mitsubishi Process.

Jan 1, 2006

By V. Montenegro

Smelting of copper concentrates in Teniente Converter produces highly oxidized slag, containing from 4 to 10 % Cu and from 15 to 25 % of Fe304. Copper recovery requires magnetite reduction at a level of 5%, determining the degree of cuprous oxide co-reduction and the liberation of copper matte inclusions. The rate of slag reduction is controlled by the mass transfer to the reaction interface. Slag stirring affects the rate of reduction and enhances coalescence of mechanically entrained copper matte inclusions. Slag reduction and sedimentation in the AC electric furnace is a commonly used method of slag cleaning. Utilization of DC electric furnace creates beneficial conditions introducing slag electrolysis additionally to chemical reductions with carbon of coke and electrodes. Application of external magnetic field, interacting with a direct current in an electric furnace, induces magnetohydrodynamic phenomena, such as intensive stirring and electromagnetic buoyancy force acting on inclusions. Laboratory scale research in simulated DC electric furnace with a superimposed magnetic field showed a significant acceleration of the rate of slag reduction and copper removal. Continuous measurement of gas flow and composition allowed for determination of the reduction rate along the time. Application of external magnetic field in the reduction of the industrial slag in a crucible simulated DC electric furnace results such as the increase of the reduction rate from 2 to 3 times, compared with the identical conditions in the AC electric furnace. Interaction of non-homogeneous electric field with crossed permanent magnetic field induces vigorous slag stirring, enhance mass transfer and accelerate the rate of the slag reduction. Additional participations of the slag electrolysis in the magnetite and cuprous oxide reduction as well as the acceleration of the settling of the inclusions by the electromagnetic buoyancy force affect the slag cleaning intensification.

Jan 1, 2003

By J. B. Wiskel, H. Henein

"A study was conducted to establish the effective heat transfer coefficient for a single molten droplet moving in a gaseous medium. Towards this objective, a series of quench experiments were performed on molten droplets of AA6061 aluminum generated with the Impulse Atomization technique (IAP). IAP is a single fluid atomization process capable of producing powders with a predictable mean particle size and a relatively tight standard deviation under controlled atmospheric conditions. Microstructure analysis of the atomized powder was used to establish the extent of pre-quench solidification. A mathematical model was then employed to correlate the Ranz-Marshall and Whitaker equations with the observed particle cooling behaviour. These equations were found to provide a reasonable estimation of the heat transfer conditions only when the variation in gas thermophysical properties across the boundary layer was accounted for in the model. This model formulation of droplet heat transfer has important implications with regards to active sprays and atomization processing operations IntroductionAn understanding of droplet cooling is important in atomization powder production. It is well understood that dendrite arm spacing is inversely proportional to cooling rate during solidificationl1l. Through modification of the heat transfer conditions during metal atomization, the microstructure of a powder maybe tailored to the end user. However, owing to the complexity of gas flow it is difficult to determine a heat transfer coefficient for a moving droplet. This difficulty is further compounded when complex jets and/or streams and their interactions are considered. To provide a base for these more complicated types of analyzes, two approaches have been employed to calculate the effective heat transfer conditions for a single droplet. In one approach, Megardis [ZJ developed a numerical model to investigate the heat transfer process of a free falling droplet undergoing laminar convective cooling. The effective heat transfer coefficient as a function of angular position was determined by numerically solving the fluid and energy equations for the system."

Jan 1, 1999

By K. B. McTaggart, G. Owusu, P. J. Merrin

"This study was conducted at Hudson Bay Mining and Smelting's zinc electrowinning tankhouse to determine the effects of varying levels of antimony and continuous gelatin addition on current efficiency. The levels of antimony and gelatin were varied from 0.012 to 0.030 mg/l and 0 to 10 mg/ll2 • 31 respectively, based on neutral ZnS04 electrolyte. A non-linear mathematical model relating current efficiency with antimony and gelatin was produced. The optimum operating point for gelatin was 6.5 mg/l. On the other hand the current efficiency increased with decreasing antimony levels. An interaction term between gelatin and antimony is present but is not significant enough to improve the ability of the tankhouse to handle purification upsets in antimony. Individually, the current efficiency was linear (decreasing) with antimony, and parabolic with gelatin concentration. However, at low antimony concentrations stripping of the cathode sheet was difficult. IntroductionThe zinc electrowinning tankhouse at Hudson Bay Mining and Smelting was designed in the 1930's and consists of 120 rows with each row containing ten cells. This system cascades acid from cell to cell In a row, with neutral zinc sulphate solution added to each cell through manually controlled spigots. Animal glue additions are made manually three times per day by operations personnel. The problem with this type of cell design and operation is that feed solution flows and composition can vary from cell to cell and from row to row due to the large number of manual control points. A new system which reduces the number of manual control points was designed and tested to determine if improvement in control of cell conditions would affect current efficiency. This system mixes spent acid, neutral ZnS04 electrolyte and reagents (gelatin, antimony and strontium carbonate) in a separate mix tank, ensuring that all cells receive a uniform feed solution. Gelatin was used in the test system instead of animal glue (which is presently used) because of the poor solubility and supply of industrial animal glue. The study reported here is the first in a series of experiments designed to justify the need to modify the present cascading cell feed system (Figure 1) to the proposed feed system (figure 2)."

Jan 1, 1997

By Wantae Kim, Furnia Saito, Qiwu Zhang

"A novel mechanochemical processing technique for the preparation of zeolites from kaolinite in NaOH solution was investigated. Dry and wet mechanochemical treatments combined by subsequent moderate heat treatment could accelerate the synthetic reaction for zeolites from kaolinite. This stimulating process produced zeolite-A and zeolite-X from activated kaolinite at extremely lower reaction temperature than conventionally applied for zeolites production. Conversion to zeolite-A and zeolite-X was strongly dependent on the activated state of kaolinite. Wet mechanochemical treatment modified the chemical composition of activated solids. Rapid dissolution of AIO species rather than SiO ones in the reactant solution was accelerated by wet milling together with NaOH that promoted the formation of zeolite-X of high specific surface area.IntroductionZeolites are a family of hydrated alumina-silicate minerals contains alkali and alkaline earth metals. They have a framework structure that encloses inter-connected cavities occupied by large metal cations and water molecules. Zeolites are characterized for their ability toward ion exchange and reversible dehydration. Properties of them are exploited through commercial productions of particular structural and chemical features. Zeolites are used as commercial uses for catalysis for FCC (fluidized catalytic cracking) of petroleum refining, drying reagents of gases and liquids, and selective adsorbent for pollution control [1-3]. In such purposes, artificially synthesized zeolites are employed, although natural ones are associated with hydrothermal and hot spring alteration of volcanic materials. Commercially, a hydrothermal process has been used for the preparation of zeolite synthesis. This preparation method gives zeolites of high chemical homogeneity and purity, however, this wet-chemistry-based processing is significantly influenced by reaction temperature, pH, concentration, and composition of starting substances [4]."

Jan 1, 2000

By M. A. Gerdel

In carboxylate collector flotation of bastnasite from other semisoluble salt type minerals such as barite various modifiers must be added in order to achieve selective flotation. One such modifier is a lignin sulfonate. It may function in part by acting as a sequestrant for metal ions present, preventing autoactivation in the system by metal ions derived from the minerals themselves. It also functions as a depressant for both bastnasite and barite, chemisorbing on both. However, it is shown that the lignin sulfonate functions as a much stronger depressant for barite than for bastnasite. It is suggested that the; strong depressing action on barite is related to a good fit of the sulfonate into the barite structure.

Jan 1, 1989

By P. T. Velu

Solubility of metal oxides in the molten salt electrblytes is an important parameter in the electrochemical processing of metals and alloys. The efficiency of an electrochemical process primarily depends on the quantity of metal oxide present in the electrolyte in the dissolved form and its thermodynamic properties. The activity of CeO2 was calculated using the free energy of fusion of CeO2,{ AG°m, CeO2. The AGOm,CeO2 }was deduced from the values of enthalpy, heat of fusion and melting point of Ce02. The activity coefficients of CeO2 as a function of temperature and melt composition were calculated. The thermodynamic data such as integral molar enthalpy, entropy and Gibbs energy of formation were calculated as a function of composition and temperature.

Jan 1, 1994

By Kimura. E.

Continuous estimation of phosphorus content of molten copper is required to produce phosphorus deoxidized copper in a continuous casting operation. The phosphorus content of molten copper was related to its electric resistivity, which was measured by the four-probed technique with a specially-shaped cell. In a laboratory scale, the linear relationship between the above factors was confirmed in the temperature range of 1083OC through 1200°C. The phosphorus concentration range measured was from 40 to 500 ppm. The phosphorus content was monitored successfully by measuring the electric resistivity of the molten copper in the distributor of a continuous caster in an industrial scale.

Jan 1, 1992

By Sh. Najisi, O. Lashkari, M. R. Ghomashchi, A. Charette

"One of-the important parameters in casting and foundry technology is the fluidity of molten metal. This parameter becomes particularly important when casting thin wall parts. Therefore, understanding and controlling fluidity plays a major role in fabricating sound and defect-free cast components.Semi-Solid Metai SSM, slurry is a mixture of solid and liquid, mushy zone, with solid volume fractions of 0.1-0.5 and apparent viscosity close to oil viscosity at room temperature. It flows easily under pressure and capable of making complicated shapes with high degree of die filling and integrity.In this study, the ability of the semi-solid slurry to continue to flow is investigated through the effect of different fraction solids and holding temperatures. The results show that in mechanically stirred, MS, semi-solid 356 Al-Si alloy, increasing fraction solid reduces fluidity. Furthermore, the results of MS-alloy are compared with a newly patented Rheocasting route, i.e. SEED, Swirl Enthalpy Equilibrium Device to highlight the differences of the two processes. In addition, the interrelationships between microstructural evolution and fluidity are discussed."

Jan 1, 2004

By Gerald K. Vellente

Producers of strip coated products are being approached by users to supply higher quality products and adhere to tighter specifications. Suppliers, in an attempt to assist the producers, must consider new technologies for equipment. In the past several years, the induction melting and heating industry has made great strides in developing new and innovative equipment, while improving existing technology. In the past several years, the induction melting and heating industry has made great strides in developing new and innovative equipment, while improving existing technology. In the past several years, the induction melting and heating industry has made great strides in developing new and innovative equipment, while improving existing technology. This paper will review recent developments to include improved refractory systems for ceramic pots, new channel-type inductors which are more efficient, new power control systems for existing channel-type pots, and innovative use of multi-purpose lines. Additionally, new heating applications such as galvannealing, edge heating, and post heating will be reviewed. Advanced math models for controlling heat will be discussed. Producers can easily meet the demands of their customers because of the flexibility provided by the equipment reviewed.

Jan 1, 1992