Search Documents

By Gowda H. S. Desai, A. Herbert Mervin, P. G. Mukunda

"The mechanical properties of cast iron depend on the graphite morphology and characteristics of metallic matrix. In spheroidal graphite iron these properties are affected by the nodule count, nodule percentage, nodularity, nodules per square mm, nodule types and size distribution. In this work an attempt is made to study of the effect of centrifugal and gravity casting process on the morphology and mechanical properties. A comparison of microstructure and mechanical properties of specimens of the cast are studied. It has been observed that the centrifugal effect produces an increase in rupture strain but hardness is unaffected. In microstructure it has been observed that the centrifugal effect produces an increase in the number of bigger nodules and decrease in the number of smaller nodules and an increase of nodules per square mm. It has no effect on nodularity percentage. The centrifugal casting process produces better mechanical properties.IntroductionCast iron, the first man-made composite, is at least 2500 years old. It remains the most important casting material, with over 70% of the total world tonnage [1,7]. The main reasons for cast irons longevity are its wide range of mechanical and physical properties coupled with its competitive price [l]. Gray cast iron is traditionally used in many industries because it is characterized by a flexibility of use, excellent castability, low cost, wide range of achievable mechanical properties. Gray cast irons are selected according to their tensile strength, high modulus of elasticity, good wear resistance and good machinability are desired and for this a high-strength cast iron is selected [2].Flake Graphite and Spheroidal Graphite irons are predominantly being used to manufacture heavy automobile components throughout the world. The properties of gray iron castings are much dependent on foundry practice. Perhaps the most interesting feature of the family of cast irons is the morphology of the graphite phase, which occurs as a result of changes in chemical composition, melting, melt handling techniques and the process of solidification and subsequent cooling. The significance of these differences through graphite morphology is observed primarily in their effect on the physical and mechanical properties of the iron, but in the foundries these are also known to influence the ability to manufacture sound and dependable castings."

Jan 1, 2013

By Michael J. Virnig

The formation of crud is a normal part of operating a solvent extraction circuit for the recovery of copper. It periodically must be removed from the circuit. This results in significant costs in terms of manpower, downtime, and loss of circuit organic. Field studies have been carried out that show that the presence of a thermodynamic modifier in the organic phase contributes to crud formation. In an effort to better understand what factors contribute to crud formation, laboratory studies involving competitive adsorption studies with model solids have been carried out. The results of these laboratory studies will be integrated with the results of the field studies to present a better understanding of crud formation.

Jan 1, 1999

By Nelson Collao I.

Loss of the organic phase from solvent extraction circuits is a major cost factor for SXEW operations. Recognized sources of loss include evaporation, entrainment, and biological degradation. The mechanisms for both entrainment and evaporative losses are well recognized. Biological degradation of the organic has not been as extensively evaluated as the other mechanisms but is a major source of loss. This paper discusses the impact of biological degradation on an operating plant, potential mechanisms for degradation, conditions under which biodegradation of plant organic can occur and plant conditions that may assist in promoting biodegradation.

Jan 1, 2003

By Lawrence D. May, Harry Mudgett

"In the course of developing a new industrial process, information produced at the Research and Development (R&D) stage is critical to determining the technical and economic feasibility of the project. Understanding the fundamental operating parameters for each unit operation in a flowsheet typically comes from historical knowledge of similar systems or by technical development through a robust research program. This approach holds true for processes incorporating fluidized-bed technology. In this paper, the authors will present a practical approach for performing a research study that will allow a process owner to determine if the concept of using a fluidized-bed system can become a reality. Included are discussions of key steps required at each level of the R&D program, and the critical information required for advancing the project to the next stage.IntroductionThe conduct of a research and development program typically starts with a process owner identifying a new industrial need or modification to an existing operation. The owner can pursue this need through multiple routes, including initial in-house development, coordination through an engineering firm, contacting suppliers of key equipment envisioned for the process, or through direct contact with research and development organizations. Where and when the project is conducted is as variable as the number and types of owners who pursue them. Factors that can influence the decision of where to conduct a research program can include the type of process desired, the scale and scope of the project, the location of the project site relative to the R&D options, the experience, capability, and availability of the potential research sources, and the costs to conduct the program. Often, the owner may choose a combination of the available resources to achieve their objectives. In the end, the owner's choice should be based on a thorough understanding of their goals and objectives for the program, and a good understanding of how to measure success while achieving those objectives. Herein, the authors will describe the methods we have typically used to develop the information an owner needs to make an educated decision for investing in a new or modified process."

Jan 1, 2014

By Toshiyuki Nohira, Eiichi Takeuchi, Tetsuo Oishi, Hideki Ono, Hirokazu Konishi

Liquid metals were investigated as alloy diaphragms in molten salt electrolysis. Liquid metals have higher diffusion rates of elements than those of solid metals during electrolysis. Sn electrodes were used for the first step to study the electrochemical formation of Dy and Nd alloys in LiCl-KCl eutectic melts, demonstrating selective recovery of rare earth metals into liquid tin electrodes.

Mar 1, 2017

By Luis W. Pommier

The developed processes, the subject of this paper, extract the hydrocarbons, halogenated organic compounds and metal contaminants from hazardous soils, rendering them non-hazardous and ready to be placed back on the ground. The processes first segregate a non-contaminated fraction from the contaminated soil. This initial task is performed using available minerals processing technology: sizing, gravity separation, magnetic separation, froth flotation, etc. The remaining contaminated fraction, is submitted to two leaching operations for the removal of organic and metal contaminants, whenever both are present or to a single leaching operation if only one type of contaminant is present. The decontaminated soil fraction is mixed with the non-contaminated fraction and is placed back on the ground. The leaching liquors, used at neutral pH, are non- hazardous. After decontamination the liquids are processed to extract the contaminants, now valuable materials, for commercialization. Organic contaminants are removed by distillation of the solvents. The metal contaminants are precipitated in their oxide form. In both cases the regenerated solvents are recycled. The decontamination processes are economically competitive with transportation and disposal of the soils to permitted facilities for hazardous materials, and most importantly the developed processes remove the liabilities from the Responsible Parties. The law establishes that these liabilities do not disappear with either fixation nor with transportation and disposal since the environmental liabilities are of the ? cradle to grave? type.

Jan 1, 1994

By Kazuyo Yokoyama

New environmental assessment model based on the Waste Input-Output analysis has been developed and applied for the "Landfill mining activity". "Landfill mining" implies the digging up of the landfilled wastes, the recovery of valuable material and energy resources and, thus, the reuse of the saved space as a new landfill site. In this study, the landfilled wastes are assumed to be treated by the gasification/melting processes. Two kinds of reactors, the fluidized bed type (FB) and the shaft furnace type (SF), have been considered in this work as the typical gasification/melting processes adopted in Japan. In FB, the dug-up wastes are heated in the sand fluidized bed zone under reducing atmosphere, Fe and Al are recovered in the metallic form, and then, the gasification/melting of residues is made in the second zone. In SF, the waste is charged in the high temperature coke bed, and the gas is recovered together with molten metal and slag. Both processes generate electric power by the recovered heat and fly ash as waste to landfill. It has been found in this study that the both processes can reduce the total volume of waste and save the available landfill space. SF seems to have higher potential for decreasing volume of wastes because of less emission than FB while FB has great benefit to recover metallic Fe and Al individually. The results of scenario analysis have also indicated that the landfill mining activity is effective for sustainable management of landfill sites.

Jan 1, 2006

By Yuanpei LAN, Minren XU, Deliang NIU, Zhu WANG, Qingcai Liu, Shan Ren

Removal of gas is the major function of RH degasser. To optimize the RH refining craft in Chongqing Iron and Steel Co. Ltd, the degassing effect of RH degasser at different degrees of vacuum was investigated using a vacuum induction furnace. In addition, the effect of processing time on the gas content dissolved in molten steel was also studied. The results showed that degree of vacuum was one of the important factors that determined the degassing efficiency in RH refining process. High vacuum degree is helpful in the removal of gas, especially in the removal of [H] dissolved in molten steel. The processing time could be reduced from 25-30 min to 15 minutes and gas content could also meet the demand of RH refining

Jan 1, 2015

By Masaaki Naito

The Japanese steel industry has a long history of introducing new and innovative technologies in the field of ironmaking. The new technologies introduced during the past ten years include technologies to use cheaper and lower-grade raw materials and fuels, measures to prolong the service life of blast furnaces and coke ovens, promotion of energy saving, use of wastes and solutions to environmental problems. This report outlines the condition of production and technological trends and technical development themes in ironmaking technologies.

Jan 1, 2006

By Brian Lightfoot

Ausmelt Technology uses a furnace/slag/lance system in a way analogous to the way a chemical engineer would use a mixed reactor. The technology is sufficiently versatile to treat materials under a very wide range of temperature and chemical conditions. At one extreme the system has been operated at temperatures high enough and oxygen potentials low enough to make iron. At the other extreme it has been operated of temperatures as low as 800°C and oxygen potentials high enough to cupel lead from silver. This versatility permits the treatment of a great variety of wastes including asbestos, mixed organic\heavy metal wastes, incinerator ash smelter residues, waste water treatment sludges, organochlorine compounds and many others.

Jan 1, 1994

By Nickolas J. Themelis

The role of copper in the economy will not diminish in the 21st century. Following the tenets of industrial ecology, production and use of copper must take into account both human needs and also how to minimize "collateral" effects on the environment. Dispersive uses will be phased out and post-use recovery of copper will increase. This will result into an advantage for smelting processes that can accommodate mixed metal scrap and waste streams. The bath smelting processes of Noranda and Mitsubishi will continue to make progress but the dominance of the Outokumpu flash smelting will not be challenged until the Noranda reactor overcomes the obstacles to the direct production of copper, thus eliminating the need for a converter.

Jan 1, 1999

By H. Aminian

Copper electrowinning (EW) is an important process in connection with the solvent extraction to produce pure and marketable copper cathodes. A phenomenological model was developed to simulate the copper electrowinning process. The simulator is used to predict the operation of the Mines Gaspe pilot plant electrowinning cells put in operation in 1996. Results confirm the potential of the simulator that would subsequently be used for student training, process optimization and assessing the performances of control strategies.

Jan 1, 1999

By G. White

Traditional atmospheres used for Aluminum annealing have been air, exothermic gas, and cryogenic purity Nitrogen. Air and exothermic gas have several problems associated with them such as surface discoloration, toxic emissions, and explosion hazards. High Oxygen levels can cause Magnesium streaking and oil staining, and therefore pure Nitrogen has been the atmosphere of choice for high quality Aluminum coils. A comparative study was made on key Aluminum alloys annealed in Nitrogen with different Oxygen concentrations to determine the effect on surface quality. The atmosphere composition inside the furnace was analyzed during the purge and heat cycle to determine its effects on purge times and exhaust emissions. The Aluminum coils after annealing were visually inspected for surface staining before and after rolling. The lab study revealed that Nitrogen with up to 1.0% Oxygen is acceptable, and did not adversely effects the surface quality or any of the other processing variables. However it isbelieved that higher Oxygen concentrations are acceptable depending on the rolling oils and alloy systems.

Jan 1, 1996

By Jannie S. J. van Deventer

Geopolymers are novel engineering materials with the potential to play a highly significant role in the transformation of the construction materials and building products industry in the push towards sustainable development. These materials are formed by activation of industrial aluminosilicate waste materials such as coal ash or blast furnace slag with alkaline solutions. Geopolymers derived from coal ash can exhibit superior mechanical properties and chemical stability when compared to ordinary Portland cement (OPC). The use of waste-based geopolymers can also result in significant (up to 90%) reduction in carbon dioxide emissions when used in cement replacement applications. In addition to the formation of conventional pre-cast products, these high performance mineral binders are ideally suited to use in the encapsulation of mine tailings, immobilization of heavy metals and back-filling of mines due to their chemical stability and resistance to acid attack. A key attribute of geopolymer technology is the robustness and versatility of the manufacturing process; it enables products to be tailor-made from a range of raw material sources (waste and/or virgin) with specific properties for a given application at a competitive cost. Despite these key technical and environmental attributes, it is the ability to add significant value to coal ash or and/ or metallurgical slag waste streams which drives the commercial development and uptake of the technology.

Jan 1, 2006

By Naiyang Ma

High zinc concentration in basic oxygen furnace (BOF) steelmaking offgas (OG) cleaning system solid wastes is one of the main barriers for recycling of the solid wastes in sintering – blast furnace ironmaking process. One of the possible solutions is to utilize zinc-free scrap in BOF steelmaking so that the BOF OG solid wastes will not be contaminated with zinc and can be recycled through sintering – blast furnace ironmaking. This paper describes a model for helping to decide whether to use zinc-free scrap in a BOF process. A model computing marginal price increment of zinc-free scrap is developed. The marginal price increment is proportional to value change of the BOF OG solid wastes after and before using zinc-free scrap, to ratio of BOF solid waste rate to purchased galvanized scrap rate, and to price of galvanized scrap. Due to the variations of consumption rate of purchased galvanized scrap and home galvanized scrap, iron ore price, landfill cost, and price of purchased galvanized scrap, using zinc-free scrap in a BOF process might be economically feasible for some ironmaking and steelmaking plants or in some particular market circumstances.

Jan 1, 2015

By S. N. Lekakh

Experimental work and thermodynamic simulations of cast iron refining were carried out using various additions of alkali and rare earth metals. The refining reactions for sulfur and oxygen removal were studied for melts treated with Mg, Ca, and Ce. The measured data and the results of the computer simulations were in agreement. Experimental kinetic data, together with the thermodynamic calculations, were used for optimization of the amount and sequence of the addition of nodulizers for ductile iron production.

Jan 1, 2009

By Andy Judge

"In traditional Permanent Magnet Machines, such as electric motors and generators, power is transmitted by magnetic flux passing through an air gap, which has a very low magnetic permeability, limiting performance. However, reducing the air gap through traditional means carries risks in manufacturing, with tight tolerances and associated costs, and reliability, with thermal and dynamic effects requiring adequate clearance. Using a magnetically permeable, high thermal conductivity material has the potential to improve magnetic performance, while at the same time offering performance advantages in heat transfer.Ferrofluids can be used to improve permeability in the rotor I stator gap. However, there are several tradeoffs in this approach. Fluid immersion comes with an increase in fluid friction loss compared to the windage losses of a traditional system. Isolating the rotating components from the ferrofluid can offset this effect. Also, while the magnetic effect can be positive for gap permeability, leakage flux can increase, and saturation can limit gains. These effects must be taken into account for a system optimized for ferrofluid immersion.IntroductionPermanent Magnet Machines (PMM's) convert electrical energy to mechanical energy in motor applications, or, for generator applications, convert mechanical energy to electrical energy through means of passing alternately polarized magnets past electrical coils. Looking at a simplified version of a PMM, where Rx is magnetic reluctance and <l>x is magnetic flux, we have the circuit shown in Figure 1."

Jan 1, 2013

By Bradford H. Miller

Separation and Recovery Systems, Inc. (SRS) provides on-site waste minimization and resource recovery using its state-of-the-art MX-1500 centrifuge and MX-2000 thermal desorber. The MX-1500 can process over 450 feed tons of material per day, resulting in centrifuged cake containing 20% to 60% by weight. The MX-2000 is a hollow-flite thermal processor indirectly heated by either steam or hot oil. SRS has dewatered and/or deoiled over 1,000,000 feed tons of material in the refining, chemical, and energy industries using the MX-1500. SRS estimates that over 300,000 barrels of reusable oil have been recovered from that material. Additionally, SRS has dried and/or detoxified over 150,000 wet tons of solids or soil to regulatory or customer-specified limits using the MX-2000.

Jan 1, 1994

By A. Filzwieser

The highest current density suitable for the electrowinning process is between 50 to 60 % of its limiting current density. One of the most important influences on the limiting current density is the thickness of the hydrodynamic boundary layer near the electrode surface. Therefore, the fluid flow in a copper electrowinning cell is calculated. The numerical simulation - using the CFD-software package FIRE® - considers all three different types of the fluid flow, namely, the natural convection, the forced convection by electrolyte circulation and the forced convection by electrochemically induced gas stirring. The simulation of natural convection is based on the different density values in the boundary layer at the electrode surface given by a density/concentration correlation. The copper concentration - linked with the current density by Faraday law - is solved by an additional transport equation. The simulation of the forced convection by the electrochemically-induced gas stirring is done by using a real two-phase calculation. That means that all differential equations are solved again for the second phase. The numerical solution of the fluid flow field is compared with the results of LDA- measurements, which were done in a special cell. The software for the LDA enabled a calculation of the void fraction possible and therefore a rough estimate of the mass transfer coefficient through the prevailing gas bubble induced convection can be made by assuming the influence of relative bubble volume.

Jan 1, 1999

By Varadajan Seshadri

Torpedo cars have been extensively used for pig iron desulfurization although its geometry is not considered to be ideal as far as mixing and mass transfer are concerned. Complications arise from scaffolds formed through aggregation of flux, slag and pig iron during operation. Following industry demand a 1:6 torpedo car physical model was operated to assess the optimum refining conditions for pig iron desulfurization. Similarity between the model and prototype were established through Froude and turbulent Reynolds criteria. Mixing times were evaluated by pulse tracer addition and the kinetics of metal/slag interactions were assessed from experiments investigating iodine transfer from kerosene to water. The influence of parameters such as level of metal, gas flow rate, lance penetration, lance orientation, presence of scaffold were evaluated. Mixing times were found to be shorter than regular desulfurization time and also not very sensitive to scaffold presence. Scaffold contributes to the reduction of the useful volume only. Mass transfer at the permanent reactor is more effective when the torpedo is operated at its full capacity. The experiments also highlight the dominance of the transitory reactor as compared with the permanent reactor.

Jan 1, 2006