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By Hani Henein

"Heat transfer between droplets/particles and a gas phase plays an important role in the transport of numerous materials processing operations. These include rapid solidification operations such as gas atomization and spray forming, as well as chemical systems such flash furnaces. Chemical reaction rates and solidification are dependent on the rate of gas-particle or gasdroplet heat transport. Using a heat transport model validated using single fluid atomization of molten droplets; the effect of process variables on heat losses from droplets was examined. In this work, the effect of type of gas, droplet size, gas temperature, gas-droplet relative velocity on the heat transport from AA606 l droplets was examined. The most critical of these process variables to heat transfer is identified and will be presented.IntroductionIn materials processing, droplets are often encountered and used in processing a wide range of liquids and slurries. The small size of the droplet enables high reaction rates or high solidification rates in many systems. In order to capitalize on these high rates of transport processes, sprays are· also developed to maximize throughput. The design of these sprays, however, does not account for the transport steps and rate limiting mechanisms at the droplet surface. Rather, spray design focuses on maximizing the break-up of a stream or slurry into small size droplets or controlling the spread of the spray. Spray systems in industrial use typically generate droplets of wide size distribution leading to a wide range of reaction times for each of the droplets. Often the generation of a spray involves a number of coupled phenomena such as stream break-up, droplet-gas transport, droplet size distribution and spray geometry. Using gas generated sprays, it is not possible to identify how individual process variables contribute and control each of these coupled phenomena. While many mathematical models have been developed of sprays and they attempt to simulate coupled droplet transport, they do not provide insight into the contributions of different mechanisms in heat transfer. This is primarily because the basic fundamental heat transport between droplet and gas cannot be isolated from other gas spray phenomena experimentally such as two-way thermal coupling [l]. Thus, experimental validation of heart transfer of large and complex industrial spray models is not carried out. Hence, the validity of spray models remains in question and the approach required to optimize spray processes cannot be clearly identified"

Jan 1, 2004

By Y. Fautrelle, F. Felten, O. Metais, Y. Du Terrail

"We deal with the prediction of electromagnetically-driven turbulent flows by means of a Large-Eddy- Simulation method (LES). The model is applied in the case of a liquid metal pool submitted to a polyphase linear electromagnetic stirrer. We investigate two cases: (i) the frequency of the magnetic field is equal to 50 Hz; in that case the effects of the pulsating part of the Lorentz forces may be neglected; (ii) the frequency of the magnetic field is low (f= 1 Hz), then the oscillating part of the electromagnetic forces is taken into account. The LES predictions agree well with the mean velocity measurements, as does the standard k-a model. However, as for the turbulent kinetic energy predictions, there is a large discrepancy between the two models. When the oscillating part of the Lorentz forces is taken into account, the computations show that the fluid flow is sensitive to the unsteady part of the forces. We find that the mean velocity is not affected by the fluctuating component of the force. As for the turbulence parameters, the presence of the pulsating part leads to a significant reduction of the turbulent kinetic energy, whilst the turbulence length scale decreases.IntroductionElectromagnetic stirring is commonly used in various metallurgical processes. In continuous casting for example, it may improve the structure of the solidified metal products. Fluid flows generated by electromagnetic stirrers have been extensively investigated (1 ). As for numerical predictions, many works have been published on the subject. In most of the previous works, onepoint closure models have been used. The most used model is the well-known k-i:: model. Those models yield fairly good results as for the mean velocity prediction. However, it has two main drawbacks:(i) the turbulence is not predicted accurately,(ii) it is not well fitted for unstationary flows as well as transitional turbulent motions, where theReynolds number is moderate."

Jan 1, 1999

By Chang Wei, Zhigan Deng, Jiqiang Liao, Minting Li, Hongsheng Xu, Yan Song, Cunxiong Li, Xingbin Li

"Abstract: Direct ?otation of oxidized zinc-lead ore is characterized by recovery of zinc and lead only around 55% and 50%, respectively. Mineralogical analysis shows that the sample used in the present study is a carbonate hosted zinc-lead ore, with a zinc and lead carbonate content that accounts for 80.14% and 75.63% of the total minerals, respectively. The carbonate hosted zinc-lead ore was hydrothermally sulfidized with elemental sufur and the experimental data indicated that under the conditions employed up to 75% zinc and 82% lead sulfidation extent were achieved. As a result of pre-sulfidation followed by flotation, the recoveries of zinc and lead into flotation concentrate were over 90%. A flotation concentrate was obtained with 52% Zn and 37% Pb from the materials which was treated by sulfidation.IntroductionSulfide ores are the primary source of zinc and lead, and they are becoming depleted; thus, metallurgical investigators are interested in using abundant oxidized zinc-lead ore reserves. The high-grade zinc-lead oxidized ore, which normally has a zinc content higher than 15%, can be disposed of by acid leaching and electrolysis. However, the low-grade ore, which has a zinc content lower than 10%, is difficult to smelt with pyrometallurgy and hydrometallurgy, and the processes are very complicated and expensive in terms of production flow and energy consumption. Therefore, making the low-grade oxidized zinc-lead ore more beneficial has become more important in recent years. Flotation is the most common process, and the primary method of recovering zinc and lead from sulfide or oxide minerals. It is well known that there is a difference between sulfurized and oxidized minerals regarding their separation by flotation. Flotation of zinc and lead oxidized minerals is extremely complex because of the similarities in the physicochemical and surface chemistry of the constituent minerals. There are no known direct-acting collectors capable of producing single metal concentrates [1-3]."

Jan 1, 2012

By Cong Wang, Kexin Jiao, Yongan Zhao, Haibin Zuo, Jianliang Zhang

The carbon composite brick is a new refractory used in blast furnace hearth and bottom. It caused wide attention due to its high thermal conductivity and low erosion by molten iron. In this paper, chemical constituents, SEM-EDS and X-ray diffraction were carried out in order to understand reaction mechanisms. A series of experiments of oxidation resistance characteristics were made. The oxidation mechanisms of carbon composite bricks in the presence of air were analyzed. According to the analysis on many experimental results, the oxidation process of carbon composite bricks under different temperatures were controlled by different mechanisms. In the condition of high temperature, SiO2 as oxidation product hindered the diffusion of O2, and reduced the oxidation loss of graphite in the internal.

Jan 1, 2015

By Bingyi Bai, Wangjun Peng, Yanling Guo, Jieyu Zhang, Guoding Gao

The phase transformation of bayan obo ore with high concentration of iron and calcium was reduced at temperatures no more than 1000℃ were investigated in this study. The samples with insufficient carbon were treated at the temperature using a vertical furnace with a thermogravimetry (TG). The mineral phases and content were examined using Xray diffraction (XRD) and X-ray fluorescence spectroscopy (XRF) respectively. The complex phases of bayan obo ore transformed to some simple phases after treated with different content of carbon at the same temperature for 10 hours. The result of XRD、 XRF and TG showed that the reduction degree of Fe3O4 phase formation varied with the temperature and the carbon content of bayan obo ore.

Jan 1, 2015

By Zhiqian Zhang, Chao Wu, Chao Li, Hongxu Li, Yu Chen, Xiangxin Hao

"In this paper, the life cycle assessment models for automobile lightweight materials including high-strength steel, aluminum alloy and magnesium alloy are developed by Gabi software. The evaluation models and evaluation indicators such as acidification effects, rich eutrophication effect, ozone layer depletion effects, global warming, resource consumption and formation of ozone potential were taken into account. It is shown that the effects of acidification and ozone formation are mainly derived from the run phase of high-strength steel and they have strong environmental impact load. While considering the entire life cycle with materials production phase and resource consumption, the aluminum and magnesium alloy appe art o have large r environmental load than high-strength steel. Base d on the evaluation, some optimization tips are proposed.IntroductionAs the increasing of car ownership, automobile has its two sides. One which is the convenient, efficient and fast traffic vehicle; the other is aggravating energy consumption, emissions and environmental pollution. The car industry faces heavy pressure with energy saving, safety and environmental protection. Nowadays, the main study ways for automotive energy-saving and environmental protection are power system improvement, alternative energy sources and technologies. For limitation of technique, development cycle and market share, the development of car is little progress at this stage and the application has been restricted. And another important way is the lightweight of vehicle. Usually there are three ways to get the lightweight automobile body structure, automobile body structure optimized design, using advanced body manufacturing technology, development and application of lightweight high strength body material.The life cycle assessment (LCA)[1lis commonly used to evaluate environmental factors and potential environmental impacts of products and services. As an environmental management tool of product-oriented, it becomes increasingly popular in industry. In this study, the concept of LCA and GaBi software was used to develop models for the three automotive lightweight materials, evaluate the environmental impact and make horizontal and vertical contrast by choosing variety of evaluation systems and indexes."

Jan 1, 2013

By Junji Shibata

Zeolite synthesized from coal fly ash has many intelligent properties such as cation exchange, adsorption, catalyst and so on. The suitable use of the zeolite, however, is not established in an actual commercial scale yet. From the viewpoints of an effective usage of coal fly ash and the zeolite obtained from coal fly ash, we propose the new concept for environmentally friendly usage of zeolite, in which coal fly ash safely returns to the soil with growing plants and purifying wastewater. This method can make great contribution to recycle of coal fly ash, to purification of high nutritious water and to tree planting.

Jan 1, 2002

By Mike Adams

A comprehensive pre-feasibility study has been conducted by Companhia Vale do Rio Doce CVRD) for Niquel do Vermelho nickel laterite deposit. Within this study, five integrated flowsheet options were evaluated via batch and pilot campaigns at Lakefield Oretest, over an intensive six-month period from receipt of ore to final reporting. Key technical objectives set by the client included demonstrating the technical viability of the beneficiation of several ore types, processing through integrated pressure acid leach/mixed hydroxide precipitation (PALIMI-IP) and mixed sulfide precipitation (PALIMSP) circuits, and the treatment of barren liquors to meet stringent environmental requirements. Refining of the MHP was by ammonia re-leach and solvent extraction (SX) to produce LME-grade nickel cathodes, NiCO3, NiO and CoS. LME grade nickel and cobalt was also produced by oxidation of the MSP and hydrogen reduction on the leachate. The database and data acquisition system, along with web-based reporting, enabled rapid turnaround on both daily and more comprehensive run reports, making it possible for speedy and confident decisions on operating conditions of the complex flowsheets. The high value of developing such data is emphasized and discussed as pivotal in the successful progression of laterite projects through to sustainable commercial viability. Keywords: Flowsheet, CVRD, Nickel, Piloting, Pressure, Leach, Refining.

Jan 1, 2004

By Jie Ma, Bo Wang, Jieyu Zhang, Jian Zhao, Guangxin Wu, Shunli Zhao

"Nucleation and growth model based on a 3D CAFE model, which was incorporated with macro heat transfer calculation within ProCAST software was used to predict the solidification microstructure of austenitic stainless steel in twin-roll strip casting. The simulation results of solidification microstructure agreed well with experimental results of austenitic stainless steel. The effect of different casting process parameters on the solidification microstructure was simulated. The predicted results show that solidification microstructure is obviously sensitive to superheat and convection heat transfer coefficient. With the increase of superheat, the grain density decrease and the proportion of columnar crystal increase. In addition, the proportion of columnar grains increases when convection heat transfer coefficient increases. Thus, it was demonstrated that the solidification microstructure evolution of twin-roll strip casting could be predicted reasonably by using this model.IntroductionNear-net-shape casting technology is an important research area in the iron and steel industry today. Twin-roll strip casting represents a major area of concentration of near-net-shape casting technology. It has been widely used for its outstanding advantages, such as extended solubility of alloying elements, refined solidification microstructure and reduced microsegregation [1]. Furthermore, it is the most environmentally friendly, energy saving, and C02-sensitive way to produce steel strips [2]. Therefore, much attention remains to be paid to this aspect. A lot of published works indicated that the solidification microstructure of twin-roll thin strip has obvious effect on the thin strip properties [3, 4]. For the accurate control of parameters of the process are made difficult due to the complicated process and the multi-fold factors, great attentions have been paid to numerical simulations to provide insight into the solidification behaviors of the thin strip formed by twin-roll strip casting [5, 6].Simulations of casting solidification can provide a method to predict microstructure and to improving strip quality by controlling the process parameters."

Jan 1, 2014

By Yan Fu, Chuanlin Fan, Xiujing Zhai, Yongfeng Chang, Binchuan Li

"The mechanism of the selective chlorination of nickel and cobalt in reduced limonitic laterite was investigated. Reduced ores were obtained from the reduction roasting of a limonitic nickel laterite. The thermal decomposition of related chlorides and the selective chlorination of the reduced ore were carefully studied using Differential Thermal analysis - Thermogravimetry (DTA-TG), X-Ray Diffraction and chemical leaching methods. In the temperature range of 300 - 500 °C, aluminum chloride hexahydrate was chosen as chloride agent. During the selective chlorination, reduced ore was partly chlorinated by hydrogen chloride generated from the thermal decomposition of chloride agent. Then the oxydrolysis of ferrous chloride re-generated hydrogen chloride was used to further the chlorination. Finally, iron was mostly rejected as hematite, while nickel and cobalt were selectively chlorinated. More than 91 %Ni , 90%Co and about 4%Fe in the chlorinated ore was extracted using a water leaching method.IntroductionLimonitic nickel laterite is an important nickel reserve, which is rich in iron in the form of goethite and has low contents of magnesium, aluminum, silicon, and other elements. Goethite is the main nickel-bearing mineral in the laterite [1]. Nickel is generally present in goethite in three modes: (a) associated with amorphous or poorly crystalline goethite, (b) weakly adsorbed to the crystalline goethite surface, and ( c) as lattice substituents [2]. In addition, cobalt in limonite was found to be associated with a manganese phase rich also in nickel [3]. These results indicate that the extractions of nickel and cobalt are highly dependent upon the degree of the decomposition of the nickel, cobalt-bearing minerals.For the selective extraction of nickel and cobalt from limonitic laterite, the ore is usually processed by hydrometallurgical methods, including high pressure acid leaching (HPAL) [4] or reductive roasting - ammonia leaching (Caron process). However, there are still some disadvantages in these processes, such as the expense of autoclaves and scaling problems in HP AL [ 4, 5], and relatively low overall metal recovery, large energy and reagent requirements for the Caron process."

Jan 1, 2011

By Huasheng Chen, Gaifeng Xue, Jing Zhang, Mingsheng He, Bin Liu, Yexian Ouyang, Shoujun Peng

Based on the investigation and study of the topography, microstructure and composition of the buildups which form in the surface of carbon sleeve in continuous annealing furnace for lowand medium-grade non-oriented silicon steel produced by CSP process, combined with production process of silicon steel, the mechanism and major causes for forming buildups of carbon sleeve are discussed from the factors such as CSP process, the quality of carbon sleeve and so forth. Meanwhile, some countermeasures to reduce the formation of the buildups are put forward.

Jan 1, 2015

By Jose Antonio Silva Souza, Emanuel Negrao Macedo, Iara Ferreira Santos, Otacilio Dias, Luis C. A. Venancio

"The Bayer process alumina production generates 0.7 to 2.0 ton of bauxite residue (BR) and an average of 1.0 ton of C02 per ton of alumina produced. The direct reaction of exhaust gases to reduce the alkalinity of the BR may allow a triple gain: improve the storage conditions, open a range of new applications for BR and sequester from 16 to 102 kg of C02 per ton of alumina. This paper shows the measurement of C02 captured during a pilot scale reaction of a suspension of BR in water with flue gas, produced from direct oil burning. Three different types of reactors were used: one spray tower and two packed columns. The inlet and exhaust gases were analyzed using electrochemical and non dispersive infrared sensors. The pH of the suspension was monitored during and after the reaction to evaluate the buffer effect.IntroductionAlumina is mainly produced from refining bauxite using the Bayer process. This process consists of extracting the aluminum oxide through its dissolution in caustic soda and the separation of insoluble residues. The remaining bauxite residue (BR) although not particularly toxic, poses risks to the environment due to the large volume and its reactivity. According to the latest technology it is stacked on sealed deposits specially constructed. To date the vast majority of the bauxite residue that has been produced was stored and were not incorporated into any existing production processes to significant amount with exception to some extent of the sintering process residue at Russia and China [l]. On the other hand, a strategic goal was set in 2010 by the Bauxite and Alumina Committee of the International Aluminium Institute (formed by the majority of the industries) to reuse 20% of BR in 2025 [2]. China has established the same objective for 2015[1].This paper is a sequel of two others presented at TMS 2010/2012 [3-4] and describes:• A pilot plant assembled for testing the carbonation process of BR with gaseous effluents similar of the refining process.• The methodology used to measure the amount of C02 captured during the carbonation process.• The results of the carbonation process, the C02 capture and the buffering effect of the pH.This process is studied in order to consume minimal power and use the effluent as efficiently as possible in different reactors from low cost to ultra high performance. The process is designed for minimizing the power consumption and equipment investment."

Jan 1, 2013

By A. J. Paul

Traditionally, 16"/50 caliber projectile shells have been fabricated from forged steel. The Naval Surface Warfare Center (NAVSWC) has determined that cost savings of approximately 60% (-$4.7M/year) as well as improved shell fragmentation can be achieved by casting these shells from austempered ductile iron. One of the technical concerns arising out of this material substitution is the role of the casting process in controlling the quality of the cast shells. Optimizing the process through proper orientation of the mold, placement of chills, superheat, etc., can minimize shrinkage porosity and, consequently, flaw size. For this purpose, the mold filling and subsequent solidification of the projectiles was simulated using a 3-D, fully transient, coupled fluid flow and heat transfer model based on finite differences. Several casting orientations were investigated and the casting parameters were varied to optimize the process and minimize casting defects. A comprehensive software tool, which was developed using state-of- the-art visualization techniques, has been used to analyze the process of casting. Emphasis is placed on the use of this visualization tool as an aid to the foundry engineer for process optimization.

Jan 1, 1992

By Kimio Itagaki

"As a contribution to understand the smelting of copper or nickel matte by blowing oxygen or oxygen-enriched air, the phase equilibrium and the distribution of minor elements between the iron-silicate based slag and the Cu2S-FeS or Ni3S2-FeS matte at 1573K were investigated in a magnesia crucible under controlled partial pressures of SO2 at 0.1, 0.5 and 1.atm. At a given matte grade, the solubility of copper in the slag was found to be independent of p5O2 while that of nickel was dependent on pSO2 and these behaviors were analysed thermodynainically based on a concept of oxidic and sulfidic dissolution of the components in the slag. When the matte grade was specified, the distribution ratios of X, defined as (wt pct X in slag)/(wt pct X in matte}, for As, Sb and Bi increased with increasing p5O2 while that for Ag was constant against p5O2.IntroductionA combination of intensive reactors with the use of oxygen or oxygen-.enriched air as the blowing gas has provided a number of improved copper and nickel smelting processes such as INCO-Flash, Outokumpu-Flash, Mitsubishi-Continuous and IBRC (top blown rotary converter) processes. Phase equilibrium and thermodynamic studies for the slag and the copper matte or the nickel matte under high partial pressure of SO2 are of practical importance for evaluating the behaviours of the related components in the oxygen-smelting.A series of experimental studies have been already conducted in a limited range of conditions for Pso2 around 0.1 atm, which corresponds to the smelting with air-Stowing [1-5]. However, there remain very few data on the phase equilibrium in the matteslag systems under higher partial pressures of SO2. Tavera and Davenport studied the phase equilibrium between the copper matte and fayalite slag phases under the partial pressure of SO2 controlled at 0.1 - 1 atrn but without controlling the partial pressures of sulfur and oxygen [6]. A potential diagram for the Cu-Fe-S-O-SiO2 system at 1523 - 1573K suggests that the partial pressure of S2 equilibrated with the matte and the fayalite slag with saturated SiO2 under the high SO2 pressure is considerably high at 10-4 - 10-2 atrn [7]. This condition must require controlling of p52 as well as Pso2, in the equilibrium experiments, otherwise, the equilibrium condition may be hardly attained due to the continuous flushing of sulfur from the system."

Jan 1, 2000

By T. Manlyama

The Tamano Smelter of Hibi Kyodo Smelting CO., Ltd. went into operation in 1972. The Flash Smelting Furnace that was originally adapted was equipped with electrodes that were attached to the settler substitute of the slag cleaning furnace. Later the development of our own original coke combustion technology was promoted and a new Tamano Type Flash Smelting Furnace (T-FSF), without electrodes, was put into operation in 1988, T he technology of coke combustion and combustion the burner have continued to improve. As a result the copper losses in the Wag have been reduced as well as a stable operation has been achieved, Furthermore; this has been accomplished while increasing the concentration feed and the matte grade. The current objective is to continue to strive for high matte grade operation and to raise production efficiency while paying attention to the important subject of copper losses in the slag. In this report, the data related to the copper loss in the slag reduction are presented along with the influence of the thickness, settling time and coke. The recent operation conditions of the T-FSF are also presented.

Jan 1, 2003

By William Brinkman, Mark Jolly, Nasim Soleimanian, Karl Dearn, Oliver Brinkman

"Glass manufacturing is a heat intensive process. There is a direct correlation between the batch distribution techniques and the furnace energy consumption, productivity, and quality of the glass manufactured. All four major segments (float, container, fibre, and specialty glasses) would benefit from using an optimised batch distribution technique where possible. Oscillating batch chargers (OBC) have been in use since the early 70s, despite their superior batch shape, coverage, and in turn positive effects on the energy consumption and productivity of the furnace they are almost exclusively used in container glass manufacturing. The OBC’s main difference compared with other charging methods is its ability to directly influence the batch initial velocity. This paper reports on results achieved in CFD models (GFM) used to study effect of the machine on the overall energy consumption in the doghouse and the melt space.IntroductionGlass manufacturing can be divided to four major segments float glass, container glass, fiberglass, and specialty glasses. The financial cost of manufacture, its impact on the environment, lack of standardisation and mounting pressure imposed by the authorities for reduction in emissions means that the industry and its suppliers are utilising CFD modelling in order to tackle these challenges. The need for high temperature to create and maintain the viscous flow, homogenisation of the glass melt, and maintenance of the process to allow continuous output of glass of the right quality are the contributors to the energy intensive activities that are involved in continuous glass manufacturing. This in turn has resulted in design of large container glass furnaces which have high energy consumption, low specific performance, and high CO2 emissions where the most efficient furnaces in the container glass sector have a specific primary energy consumption of 3.8 GJ /tonne of glass at a level of 50% cullet in the batch making even very small improvements in efficiency by operation optimisation a value adding activity [1-14].The theoretical calculated energy required to melt glass is 2 to 3 times less than the energy actually used to melt glass as a result of glass melt passing a zone 5 to 8 times before leaving the tank.[8]. This causes contamination as the result of mixing between the completely molten glass free from bubbles returning to the batch area where there is freshly molten non-homogeneous glass, still containing very large numbers of bubbles and un-molten batch. At high temperature some components are dissolved rather than melted. Given that an un-molten batch is a good thermal insulator, it can be transported a long way into the furnace, increasing the need for homogenization which also increases the glass residence time of glass melt. This is why large unbroken strings of batch should be avoided, as should an overall blanket without gaps."

Jan 1, 2014

By Dan Wang, Qian Xu, Guangshi Li, Xionggang Lu, Xingli Zou, Zhongfu Zhou, Hongwei Cheng, Changyuan Lu

The preoxidation of the ore has a profound significance to the concentration, separation and purification of nickel and copper from the lean complex ore. In this paper, the natural Ni-Cu sulfide mineral samples under the elevated temperature condition in air were investigated, as well as under isothermal condition at 600 oC in air. The mineralogical characterization was studied using XRF, ICP and the Rietveld method. The oxidation behavior and the element migration of the Ni-Cu sulfide ore were studied by XRD, SEM-EDS and TG. The XRD Rietveld method was successfully developed in the phase identification and quantification of this complex ore powder sample. The oxidative intermediates (Cu/Ni-ferrite) were detected by XRD, and the process of the element migration was obviously revealed by the line scans using SEM-EDS. It is the preoxidation of this mineral that provides guidance for the extraction of valuable metals from low-grade Ni-Cu sulfide ores in the future.

Jan 1, 2015

By Aichun Zhao, Rui Wang, Yihong Li, Yanping Bao, Yafeng Ji, Jiansheng Liu, Xiao Hu, Qingxue Huang

The slag entrapment under different conditions of 80t blowing argon ladle furnace was investigated by physical simulation. The water was used to simulate liquid steel and liquid paraffin was for slag. The processing of slag entrapment under different blowing structures was analyzed and the critical velocity and critical droplets diameter of describing it was obtained. Based on the experiments, the relationship between the interface flow velocity and the critical blowing rate CBR was deduced. In the real process, it is suggested that the bottom blowing rate is from 40 L/min to 180L/min when the interface tension is 0.12~1.2 N/m during the soft argon blowing.

Jan 1, 2016

By Hideki Yarnarnoto

The simultaneous removal for NH4+ and PO43- in aqueous solution was carried out by using Ca type zeolite synthesized from coal fly ash. The effect of pH on the cation exchange capacity and adsorption properties of the obtained zeolite, the simultaneous removal of NH4' and ~04'. in various solutions and the mechanism of simultaneous removal were investigated respectivel? ,The Ca type zeolite used in this study can simultaneously remove NH4+ and PO43- In aqueous solution without releasing counter ion, and this method gives great advantage over the other ordinary removal methods.

Jan 1, 2002

By Y. Y. Liu, H. M. Domanus, W. T. Sha

"Casting is fundamental to manufacturing of many types of equipment and products. Although casting is a very old technology that has been in existence for hundreds of years, it remains a highly empirical technology, and production of new castings requires an expensive and time-consuming trial-and-error approach.In recent years, mathematical modeling of casting has received increasing attention; however, a majority of the modeling work has been in the area of heat transfer and solidification. Very little work has been done in modeling fluid flow of the liquid melt. This paper presents a model of fluid flow coupled with heat transfer of a liquid melt for casting processes. The model to be described in this paper is an extension of the COMMIX code and is capable of handling castings with any shape, size, and material. A feature of this model is the ability to track the liquid/gas interface and liquid/solid interface. The flow of liquid melt through the sprue and runners and into the mold cavity is calculated as well as three-dimensional temperature and velocity distributions of the liquid melt throughout the casting process.IntroductionBower et al. (1), in their 1969 review of the evolution of some of the casting techniques, stated that:""The evolution of technology requires alternatives to be available so that choices can be made that lead to changes. The role of solidification science and other disciplines related to casting technology is to develop a better understanding of process and product, so that a wider range of alternatives is possible.Alternatives, whether from science or from invention, must lead to improvements in casting ""utility."" Utility, or economic advantage, must include consideration of total system costs, and final product value. The cost of materials, melt processing and finishing should be optimized with casting costs, since all are part of the production system. It is the favorable relationship between total processing costs and product value that makes a change in casting technology viable, but the best change is not possible unless technology has provided an understanding."""

Jan 1, 1986