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By M. B. Mesina

Mechanical separation systems are widely used nowadays for scrap metal processing, but they have natural limitations in product quality. The quality of the final product is considerably improved when sensors are used in the separation process. This paper describes new methods using sensors for scrap metal sorting and quality control. An example is the electromagnetic sensor, which uses the electrical and magnetic properties of materials to distinguish between different non-ferrous metals. The measurement results of two prototypes are reported. The benefits and the possibility to integrate such systems into practical applications regarding the processing of secondary raw materials are also described.

Jan 1, 2003

By I. Hilerio

Chromium Nitride (CrN) thin films were deposited on AISI steel 316 substrates by means of the reactive magnetron sputtering method. CrN films were produced under two different conditions. In the first one, the substrate was heated by a DC source. For the second coating a negative substrate bias voltage was applied. X ray diffraction, quantitative energy dispersion and scanning electron microscope were employed to characterize the two different phases, their chemical composition as well as their microstructure. In addition, a microhardness test was carried out. The results show that a better phase formation of CrN thin films was achieved when a heating source was present (first case). Both coatings presented homogeneous surface. Their compositions show differences even when the gases flowing are the same in composition. Regarding to the hardness test results, there can be found a higher value when using a heating source.

Jan 1, 2009

By M. A. Cocquerel

External process energy requirements and air pollution control regulations formulated to limit particulate and SO2 emissions are impacting on smelting and converting technologies and the corresponding process and secondary gas handling systems. This paper presents an overview of the different technical solutions used for cooling and dedusting the process gases in the different pyrometallurgical copper concentrate stages, including: drying, smelting, converting, slag cleaning and fire refining. The main principles of the process gas handling systems are presented &d a qualitative technical and economical comparison is discussed in relation to process changes, energy recovery and marketing or disposing of the various sulfur fixation by-products. Finally, a brief review of the methods for fixing sulfur contained in the process and secondary gases is presented.

Jan 1, 1999

By K. Nona C. Liddell

There is a significant amount of early work that has been largely forgotten that deals with the validity of the pseudo-steady approximation for liquid-solid reactions. Much of this was originally published in the chemical engineering literature but is highly relevant to hydrometallurgical processes. The purpose of this paper is to summarize some criteria that were been developed by various authors for determining the error associated with use of shrinking core models for liquid-solid systems.

Jan 1, 2002

By Huimin Lu, Qiang Li, Jingbo Xu

"The smelting reduction of V-Ti bearing beach placer by combined rotary hearth furnace and direct current arc furnace was studied in laboratory. It takes the aid of back propagation (BP) neural network theory to build the nonlinear mapping relations between the crucial process variables such as content of carbon, temperature and time and the degree of reduction. Then by the integrating BP neural network and genetic algorithm (GA), the optimized process parameters for the high degree of reduction were searched. The comparisons between experiment results and neural network simulation results show that GA-based on BP method can predict the degree of reduction with higher prediction accuracy. Calculations show that the integrated energy consumption of new technology is 580kgce/tHM, less than the current existing blast furnace.IntroductionThese V-Ti bearing beach placers (VTBBP) are secondary Fe-rich minerals formed by rivers, ocean waves, ocean tides and ocean currents on beach zones, their useful minerals are V-Ti magnetite ores. On Asia Pacific zone, such as Japan, China, Philippines, Indonesia, Australia and New Zealand, the VTBBP have large reserves and wide distribution. But so far, the VTBBP are not still comprehensively utilized. Therefore, in this paper, a combined rotary hearth furnace technology and arc furnace smelting method is studied for comprehensive utilization of the VTBBP. The main objective of this paper is to find optimum operation conditions for the production ofV-bearing iron and titania-rich slag from the VTBBP by means of the laboratory testing.Recently, neural network (NN) expected to be able to provide an effective tool because of its advantages, which describe nonlinear mapping relations. With the characteristics of strong selflearning, self-organization, robust error toleration and accurate nonlinear relation approximation, artificial neural network can be applied to nonlinear process modeling based on sufficient training. Back-propagation (BP) training algorithm is probably the frequently used one in practical application. Genetic algorithm has parallel search strategy and global optimization characteristics, which makes the trained neural network being higher classification accuracy and faster convergence speed. So it is necessary to combine neural network and genetic algorithm. The nonlinear relationship between input and output presented by NN and the global optimal function of GA are abroad applied in the engineering and scientific research [1, 2]. So these methods supply an efficient path to solve the above problems. At present, it is common to study the optimization of process parameters by orthogonal experimental design, the method combining neural network and genetic algorithm is a novel and better method than orthogonal experimental design. Tills study organized the above advantages to optimize the process parameters for comprehensive utilization of the VTBBP."

Jan 1, 2012

By Ali P. Gordon, James Williams

Joints gasketed with viscoelastic seals often receive an application of a secondary torque, i.e., retorque, in order to ensure joint tightness and proper sealing. The motivation of this study is to characterize and analytically model the load and deflection re-torque response of a single 25% glass-fiber reinforced polytetrafluorethylene (PTFE) gasket-bolted joint with serrated flange detail. The Burger-type viscoelastic modeling constants of the material are obtained through isolating the gasket from the bolt by performing a gasket creep test via a MTS electromechanical test frame. The re-load creep response is also investigated by re-loading the gasket after a period of initial creep to observe the response. The modeling constants obtained from the creep tests are used with a Burger-type viscoelastic model to predict the re-torque response of a single boltgasket test fixture in order to validate the ability of the model to simulate the re-torque response under various loading conditions and flange detail.

Jan 1, 2015

By T. T. Chen

The manganese oxide scales, consisting mainly of MnO2, characteristically occur in banded colloform structures which adhere to porous layers of PbSO4 and PbO2 that oxidized from the rolled Pb-0.7% Ag anodes. Hydrous Mn oxides, Mn3O4 and amorphous Mn oxides are believed to be also present. Tiny particles of gypsum, PbSO4, SrSO4 and AgCl are entrapped in the colloform masses. The gypsum originated from the Zn electrolyte; strontium carbonate was added to the ZnSO4 solution to control Pb, and silver originated from the anodes. Some of the colloform bands contain minor amounts of Pb, implying a limited degree of dissolution of the Pb during electrolysis. Other colloform bands incorporate trace amounts of Zn. Colloform structures permeated with silica gel are presumably caused by the high silica content of the electrolyte.

Jan 1, 2009

By James T. Skoch

With the ongoing pressure on the secondary aluminum business to limit the amount of waste generated from processing aluminum dross, it becomes very advantageous to preprocess the dross to reduce waste. The advantage of preprocessing is that it significantly reduces the oxides and salt cake generated when melted. Various products can be produced from the oxides for the steel industry. The following paper will demonstrate that removal of oxide fines before melting will result in large volumes of material not being landfilled. We will show that the end result of this technology is to significantly reduce the amount of salt cake sent to a landfill while maximizing the recyclability of the aluminum dross.

Jan 1, 1995

By Honggang Zhong, Wei Du, Qijie Zhai, Junjie Sun, Jingzheng Ye

"Effects of pouring temperature and cooling water flux on solidification structure of ferritic stainless steel are investigated with a thermal simulation setup. The results show that with pouring temperatures 1518° C, 1528° C, 1538° C and 1548° C, both Lmean (the mean length between columnar to equiaxed transition(CET) position and chill surface of the samples) and the mean dimension of equiaxed grains increase. On the other hand, with cooling water flux 400, 800, 1200 and 1600mL/min, Lmean gradually increases, and the mean dimension of equiaxed grains decreases. In addition, low pouring temperature and cooling water flux enlarge the ratio of fine equiaxed grains.IntroductionFerritic stainless steel plays an important role in industry products nowadays. Compared with austenitic stainless steel which contains both chromium and nickel, ferritic stainless steel can obtain good corrosion resistance despite the absence of nickel [ 1]. F erritic stainless steel has been widely applied in automotive exhaust systems [2], electrical equipment, construction and chemical industries and also has broad development prospects. At present, continuous casting technique has developed into an important technology applied in iron and steel making. The solidification structure of continuous casting slab has significant influence on the final properties of stainless steel. The developed columnar grains of ferritic stainless steel would result in negative effects on mechanical property [3]. However, fine and homogeneou& equiaxed grains can improve the comprehensive properties of ferritic stainless steel [4] Therefore, it makes great sense to promote the columnar to equiaxed grain transition (CET). Recently Baosteel has developed a new type of Cr-saved ferritic stainless steel, but the effect of continuous casting conditions on its solidification structure is unknown. It is important to investigate the effects of solidification conditions on solidification structure of this new ferritic stainless steel, which can give guidance for optimizing the production process."

Jan 1, 2014

By Rodríguez M. Esperanza

The efficient performance of Pachuca tanks is strongly linked to the suspension of mineral particles, which results from the motion of the liquid caused by injected gas rising, in general, through a central draft tube. This study reports a computational investigation on the effect of operating and design parameters on the suspension of particles. By extending the classical 2-phase drift-flux model to compute the gas hold-up, the three-phase (water-air-particles) system was simulated as consisting of a variable-density liquid plus the solid particles. These two phases were treated as interpenetrated continua using an Eulerian approach to set a turbulent recirculating flow model in 2-D and transient state. The model predicted adequately the measured critical superficial air velocity, uc, needed for maintaining particle suspensions, in pulps with 10-50 wt% solids. Additionally, the model was used to investigate the operation of industrial size reactors, obtaining results that agree well with the general trends reported in the literature, and highlighting important differences with respect to laboratory-scale reactors.

Jan 1, 2009

By Meyer Steinberg

"Some early experiences of a Cooper Union Chemical Engineer on the Manhattan project and his latest studies on CO2 Greenhouse Gas Mitigation Technologies are presented. Mitigating Global Greenhouse effect while maintaining a fossil fuel economy, requires improving the efficiency of conversion and utilization of fossil fuels, use of high hydrogen content fossil fuels, decarbonization of fossil fuels and sequestration of carbon and CO2 applied to all energy consuming sectors of the economy including electric power generation, materials production, transportation and industrial domestic heating. Decarbonization means removal of carbon as C or CO2 either before or after fossil fuel utilization and sequestration means long term disposal of C or CO2. The review will cover the principles of removal and recovery from power plant, stacks, the oceanographic and geological disposal of CO2 and the conversion of CO2 to gaseous and liquid transportation fuels. The global economic aspects of CO2 mitigation technologies are touched upon.IntroductionThis is an odyssey of a chemical engineer. My career started with the production of U235 at the Gaseous Diffusion Plant in Oak Ridge, Tennessee and the production of PU-239 metal at Los Alamos on the Manhattan Project. After 40 years at Brookhaven National Laboratory, I wound up performing studies on CO2 mitigation technologies. The following is a power point presentation on the subject of global warmingThe DOE is proposing to increase its sequestration development program in order to maintain the utilization of our vast resources in coal both for power and for transportation fuel production. Congress is considering steps to promote energy efficiency in attempts to solve not only the CO2 problem, but also the prime problem of energy supply. We will be promoting increases in energy efficiency as time goes on."

Jan 1, 2008

By Osarnu Inoue

In Mitsubishi Continuous Copper Smelting and Converting Process, smelting, slag-matte separation and matte converting are continuously carried out in series in three furnaces connected by launders. As a result of this operational configuration of the furnaces, influence of the change in operating condition in upper stream, such as variation of feeds in the smelting furnace, propagates to down stream with some delay. In order to achieve stabler operation, process control algorithm based on the dynamic characteristics of each furnace would be very effective. In this study, the dynamic process simulation model was developed for the smelting furnace. The model consists of two mathematical modules, i.e. the thermodynamic module and the mixing module. The calculation results using operating data obtained at Naoshima Smelter showed good agreement with the actually observed change in temperature, composition and flow rate of matte and slag at the outlet of the furnace. In addition, operation parameters such as reaction efficiency of oxygen and coal, dead volume of melts were estimated.

Jan 1, 1999

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 D. Mukerjee, Ramen Datta, Sanak Mishra, R. Veeraraghavan, K. L. Rohira

"Recent efforts at Steel Authority of India Limited (SAIL) has led to the successful development of atmospheric and marine corrosion resistant high tensile Thermo Mechanically Treated (TMT) bars with minimum specified yield strength of 50 kg.mm-2. These rebars are increasingly being used for a wide range of end-applications, namely, concrete reinforcement structures, bridges, flyovers, dams etc. Welding is an important processing tool for each of the above applications. In view of the importance of welding, a comprehensive evaluation of the weldability properties has been carried for the two grades of steels using Submerged Metal Arc Welding (SMAW) process; the most popularly used technique of welding of reinforcement bars (re bars).Implant tests were conducted to assess the cold cracking susceptibility of the steels. The static fatigue limit (SFL) value, determined for the atmospheric corrosion resistant (Cu-TMT) rebars under no preheat and no rebalcing conditions was found to be 63.8 kg mm-2, which was significantly higher than the Minimum Specified Yield Strength (MSYS) (50 kg.mm-2). This indicates adequate resistance to hydrogen induced cracking (HIC). On the other hand, the SFL value obtained for the marine corrosion resistant rebars (Cu-Cr TMT) under no preheat, no rebaking conditions was found to be inconsistent. Repeat of the test with fully rebaked electrodes (350°C-2h) resulted in a high SFL value (60.3 kg mm-2)_The rigidity of the structure or restraint influences the susceptibility of the weld joint to cracking. The cracking tendency increases with restraint intensity (K) of an assembly. The critical restraint intensities determined for the two steels were found to be· in excess of 1680 kg/mm.mm, indicating good welding behaviour with the following welding conditions : for Cu-TMT rebars with no preheat and no rebaking and for Cu-Cr TMT rebars with no preheat and fully baked electrodes; that is under low hydrogen levels."

Jan 1, 1998

By Jinfu Xu, Youqing Cao, Yuting Lv, Hang You, Peng Jiang

"In present work, we reported the fabrication of composites consisted of M42 powder metallurgy high speed steel and 45 steel at one step via spark plasma sintering (SPS) technology. The interface microstructure, compositions and microhardness with the interface forming mechanism were investigated. The results show that the morphology and microhardness within the M42/45 steel interfaces exhibit a gradient distribution. The interfaces possessed a transition layer up to 10.2 ?m with few distortions and microcracks. The formation of M42/45 steel interfaces were driven by both fusion and diffusion processes. The former one was primary at the early sintering process, while the later one becomes dominant over the followed sintering process.IntroductionPowder high-speed steels have been widely used in cutting tools, cold-hot tools and dies, as well as in cut materials and structure parts with wear resistance and high-temperature resistance, due to its high hardness, good wear resistance, desirable cutting toughness and favorable hot hardness [1-2]. For materials of some parts in practical production, not only the favorable toughness is required to resist the impact action, but also the high hardness and exceptional wear resistance are demanded. According to the functional requirements and working conditions, bimetal composite materials are prepared in a certain mode, proportion and distribution, by designing two metals with different chemical and physical properties [3-6]. Considering the composites exhibit different properties in different positions of the parts with a combination of the advantages of two metals, they can obtain enhanced properties that the single one can not achieve."

Jan 1, 2012

By R. Hurman Eric

The electrode in a slag-resistance electric furnace is the central factor in the design and operation of the furnace by its role of conveying the smelting power, i.e. heat needed for the operation. The control parameters are the size and positioning in the slag bath which are defined by slag resistivity, furnace resistance, cell constant and power input sequence all of which are closely interrelated. The flow of heat generated by the electrode current determines the energy distributions and thus the furnace dimensions. Heat flow models concerning vertical, horizontal and combined two-dimensional flows are discussed. All these considerations are based on the experimentally determined slag properties such as its resistivity.

Jan 1, 1995

By Toshia Ishii, Jun Kubota, Noriko Kubo

"For steel continuous castings, it is essential to control molten steel velocity at the meniscus, since the velocity is closely related to surface defects on the resultant products. Argon gas is supplied with molten steel into the mold through the submerged entry nozzle to prevent nozzle clogging. In this study, to investigate the influence of argon gas on molten steel flow, a numerical simulation was carried out by a two-phase model. Simulation results indicate that as argon gas bubbles ascend near the nozzle by their buoyancy, they induce the molten steel flow with them and resulted a meniscus molten steel flow from the nozzle to the narrow face of the mold. This flow direction is opposite to the case without argon gas. The calculated data are compared with the experimental data. The comparison shows generally good agreement between the measured and the calculated data. IntroductionIn a steelmaking process, molten steel carried by a ladle is first fed into a buffer vessel called tundish. From the tundish, it is then fed into a continuous casting mold. Molten steel solidifies gradually in the mold (the primary cooling zone) forming a solidified shell. As the solidified shell is just thick enough to support the molten steel at the mold exit, it is withdrawn through the mold by pinch rolls. It is progressively thicken as it is further cooled with water sprays in the secondary cooling zone. At the end of guide roll zone, completely solidified steel is cut into desirable lengths. Schematic view of a typical continuous casting is shown in Figure 1."

Jan 1, 1999

By J. W. Tsai

Both diamond crystals and diamond films were grown on silicon and copper substrates using a methane/hydrogen gas mixture as a precursor with thermal CVD techniques at low pressure environment. In addition to diamond particles, other crystalline phases including graphite and aluminum silicon carbide were observed on the substrate surface. ?The grown materials were analyzed with X-ray diffraction, electron microscopy, Auger electron spectroscopy and optical microscopy. Most synthesized diamond crystals were twinned. The flow rate of reactant gases, substrate nature, substrate temperature, decomposition temperature of the precursors, total pressure of reaction chamber, methane/hydrogen ratios and other possible parameters were varied during the growth processes, and the significant effects of these factors on nucleation and growth rate were evaluated.

Jan 1, 1989

By Jing Zhan, Chuanfu Zhang, Yonglin Yao

"The Ni/Co arbitrary ratios of fibrous precursor were investigated during coordinated coprecipitation by changing the precipitating medium. The results show that the original molar ratio ofNi2+ to Co2+ in reaction solution can be maintained in the coprecipitate at pH'.'05.0 and the coprecipitate is single phase solid solution using water and water-X precipitating medium. But the original Ni/Co ratios are no longer kept and composition of the coprecipitate is not uniform at pH>5.0 in water precipitation medium. In order to obtain the precursors with the required morphology and accuracy Ni/Co ratios, the optimum conditions of fibrous precursors were chosen as follows: ammonia used as complex agent and pH adjustor, water-X solvent as precipiting medium, oxalate as coprecipitated agent, 8.0-8.4 for pH value, 50-70°C of reaction temperature, 0.5-0.8 mol/L of initial nickel and cobalt salt concentrations and excesses of oxalic acid of 10% - 20%.IntroductionNi-Co alloy as an important transition metal alloy with high mechanical strength, good anti-deformation, corrosion resistance, thermal conductivity, thermal stability, electrical conductivity, electrical contact, and special magnetic properties indicates that it can be used as high-temperature catalyst, special magnetic material, high-temperature electrochemical devices, and so on [1-6]. An ideal composite powder should have an appropriate stoichiometric ratio, good uniformity of chemical composition, appropriate phase, low impurity content and small particle size [7]. Similarly, the composition of nickel-cobalt alloy powder has an important impact on its crystal structure, properties and applications. Guo[8] found that magnetisms of CoxNi1-x such as magnetic anisotropy, curie temperature, and the shifts of the spin steering are very sensitive to the composition of alloy powder."

Jan 1, 2013

By P. R. Khangaonkar

The variety of intermediates, middlings, complex materials and wastes produced in the conventional processing of tin ores as experienced in the tin industry in South East Asia is reviewed. The problems associated with the treatment of these materials so as to produce useful products by hydrometallurgical or pyro-cum-bydrometallurgical approaches are discussed. Results of treatment of amang middlings consisting of cassiterite, struverite, ilmenite, zircon, monazite etc by chlorination with carbon tetra chloride are presented. The efforts to leach tin without letting iron coming in, by alkali leaching of certain wastes of tin processing are also briefly indicated. It is felt that pyro-cum-hydrometallurgical approach can help a viable treatment of these materials so as to obtain usable or value added products.

Jan 1, 1994