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By Jin-yan TIE, Ke-xin JIAO, Qian Li, Hai-bin ZUO, Jian-Liang Zhang, Meng SHEN

This paper designs three factors such as temperature, pH, conductivity and three levels of orthogonal test. Temperature is a significant factor. However PH and conductivity are not significant through poor analysis. Further research is conducted on the temperature. Temperature stability is 50 . Suitable water velocity is 2.3m/s, which is calculated based on the largest part of the heat flux intensity and the corresponding water temperature should be controlled with 1.5. Meanwhile, water velocity increased has little effect on the heat transfer capabilities.

Jan 1, 2015

By T. Iriyama, Y. Fujita, R. Omatsuzawa, T. Nishio, N. Okochi

Sm-Fe-N hard magnetic materials are good candidates for high performance bonded magnets. Rapid-quenching method should be highly favorable for the fabrication of isotropic magnet powder with high coercivity. We report here the magnetic properties of Sm-Fe-N powders produced by a few kinds of rapid-quenching processes. Sm2Fe17 powders were prepared by gas-atomization (GA), rotating-disk atomization (RDA), or melt-spinning (MS) method. The Sm2Fe17 GA powder had dendritic solidification structure, while the RDA powder had micro crystalline structure with size of 3-5 µm. Coercivities (HcI) of their nitrides were 56 (for GA) and 217 ka/m (for RDA). The H cI of nitrided Sm2Fe17 MS powder with wheel velocity (V5) of 5-20 m/s, which had also microcrystalline structure, was 53 to 509 Wm. These coercivity values are not sufficient for bonded magnet applications. From the study of additive effects, it was found that C, C-Si, C-Ga, or C-Al addition decreased the crystal size of quenched Sm2Fe17 powder. Consequently, high coercivity was obtained; the HcI of nitrided Sm2Fe1C1Si1 MS powder with V5 of 10 m/s was 898 kA/m, and 708 kA/m for the nitrided Sm2Fe15C1Si1 RDA powder. The compression-molded bonded magnet made from Sm2Fe18Si0.1Nx MS powder showed a high (BH)max of 82.7 kJ/m3.

Jan 1, 2000

By M. Misra

The finely dispersed kerogen particulates present in the dilute suspension can be coagulated with the aid of a hydrophobic organism, Mycobacterium Dhlei. The initial coagulation and aggregation are strongly dependent on pH and organism concentration, the isoelectric points of oil shale kerogen and Mycobacterium phlei are at pH 3 and 1.8 respectively. As a result the aggregation is rapid around pH 3. Preliminary results show that it is quite possible to use microorganisms for enhanced dewatering of kerogen concentrate produced by froth. flotation.

Jan 1, 1991

By R. M. Westcott

A two-electrode, direct current, slag resistance furnace (SRF) has been constructed and operated to selectively reduce the zinc and lead contents of non-ferrous slags. The experimental SRF is equipped with multiple methods of gas/solids injection for both mixing and reaction. A computer is used to position the electrodes and for data acquisition. A geometric factor correlation was previously developed at Columbia University for calculating the electrical resistance on the basis of furnace geometry and slag conductivity. The experimental SRF was used to test this correlation.

Jan 1, 1994

By Hyun Soo Kim, Joon Soo Kim, Myong Jun Kim, Jyothi Rajesh Kumar, Jin-Young Lee

Rare earth materials have an ever growing variety of applications in the modern and hitech technology. They apply to many an industry with crucial materials and they provide numerous a customers with benefits. Rare earth materials utilization increasing day-by-day in the worldwide, at the same time the resources is very limited in many countries like Korea. The present general article divided four sorts such as 1) mineral processing of Korean ore deals the gravity, magnetic separation and froth flotation, 2) decomposition and leaching of concentrates included sodium hydroxide fritting, sodium hydroxide hot digestion, hydrochloric acid leaching, 3) separation and purification of rare earth elements in mixed rare earth chloride solution consists reduction and oxidation method, solvent extraction, 4) preparation of rare earth oxide compound from purified elemental rare earth chloride solution having oxalate salt precipitation by reaction crystallization. The last part consists of a summary of the present study.

Jan 1, 2015

By Tomás Vargas

The catalytic influence of a pure strain of Thiobacillus ferrooxidans (ATCC 19859) on the dissolution of natural pyrite crystals was studied using electrochemical techniques. The results showed that this microorganism catalyze the leaching of pyrite by both, oxidizing ferrous iron in solution and depolarizing the reduction of ferric ion on this sulfide. In addition, studies of bacterial corrosion under applied potential showed that pitting on the pyrite surface centers on weak sites of the sulfide structure in which bacteria has attached, but occurs only when the ferric iron in solution induces an adequate level of anodic polarization on the mineral.

Jan 1, 1992

By Murray Hughes, Neil Brown, John Carran

"A control system architecture has been developed using the Ward-Mellor structured analysis techniques for real-time applications. This approach has produced several advantages over traditional control system implementation methods including:•,partitioning of the control system into discrete control functions.•,easy identification of the interaction between individual control functions and the rest of the system including the impact of changes at the control system boundary (i.e. additional inputs or outputs).•,simplified control software testing.•,a closed loop design, implementation and documentation process.This paper describes a generic control application in which the process specification and control system design are logically linked. Both components are used by process engineers for on-going development.IntroductionAluminium is reduced from alumina in multiple electrochemical semi-batch reactors. Raw material additions and molten metal withdrawal are made at discrete intervals ranging from seconds to days. The electrolytic reduction process is continuous, despite the semi-batch nature of the material inputs and outputs. The chemical and physical processes that occur within each reactor are complex and interdependent, therefore simple methods used for the control of many chemical processes are impractical. The process control system is required to optimise operating efficiencies within the safe operating zone.The process control of aluminium reduction cells is heavily biased towards calculation of process variables with relatively few measured sensors. Each cell is controlled independently of the other cells, although changes to process conditions and raw material . quality will affect all cells. The process responds relatively slowly and with significant time lags. Measurements and process variable calculations occur each second, however the accuracy and precision of actuator response and sensor sampling are measured 111 milliseconds. Time-based scheduling is a significant component of reduction cell control."

Jan 1, 1994

By Zhenyang Wang, Yiran LIU, Xiangdong Xing, Jianliang Zhang, Zhengjian Liu

Basic characteristics of marine placer were systematically studied by chemical analyze, scanning electron microscope and X-ray diffraction in this paper. It could be found that the marine placer mainly consists of titanomagnetite and titanohematite. A series of experiments were performed to investigate reduction-magnetic separation for Fe and Ti from the marine placer. Effects of reduction temperature, reduction time, carbon ratio, magnetic density, and grinding fineness on the reduction-magnetic separation process were investigated. And the optimal process parameters were obtained as follows: the reduction temperature 1300, the reduction time 30 min, the carbon ratio 1.1, the magnetic density 50mT, and the grinding fineness of 0.074μm 86.34%. Under such conditions, the metallization rate, iron grade of magnetic substance and iron recovery reached to 94.23%, 97.19% and 90.28% respectively, and the titanium grade in non-magnetic substance and recovery of was 57.94% and 87.22% respectively. The effective separation of iron and titanium could be achieved in reduction-magnetic separation process.

Jan 1, 2015

By Merete Tangstad, Eli Ringdalen

"In Norway ferrosilicon/silicon and ferromanganese production are strong with world markets of 4 % / 9 % and 4 %, respectively. Research and development in the academia mirrors the national interest; hence, there has been extensive academic research in these areas. There are some vital drivers and premises for a successful cooperation between the academia and industry with the main driver being a win-win situation for both. For industry,the potential advantages include cost-, competence- or environmental- benefits; for academia, the important drivers are building of competence and equipment, educating more students at higher levels, and increased possibilities to publish. In Norway, the benefits of cooperation between industry and academia are basic knowledge regarding thermodynamic and kinetic data, as well as reaction mechanisms within core processes. In recent years, such research interests have focused on the depletion of raw materials as well as environmental issues.IntroductionIn 1989, the Norwegian Ferroalloy Producers Research Association (FFF) was funded on the belief that a common research association would benefit the industry by making it easier to perform basic research as well as paving the ground for better recruitment to the industry. The funding partners in Norway were the FeSi/Si and FeMn producers. Today, the producers are Elkem, Finnfjord, Fesil, Wacker, Eramet and Vale. The main research partners working with FFF are SINTEF (Materials and Chemistry) and the Department of Material Science and Engineering at the Norwegian University of Science and Technology (NTNU). With more than 1700 employees, SINTEF is the largest independent research organization in Norway and NTNU is the largest technical university. Together, the two organizations provide an exceptionally strong materials technology research environment, and especially so for pyrometallurgical research."

Jan 1, 2012

By Tracy T. Morris, Luis G. Navaro

"Anodic copper slimes produced during the electrolytic refining of copper are routinely batch leached to remove copper. At the Amarillo Copper Refinery, an atmospheric leaching process was converted to an autoclave pressure leaching system to improve the removal of copper, reduce the consumption of oxygen, improve leaching times and enhance tellurium recovery. The benefits of pressurized versus atmospheric leaching of slimes were soon realized by obtaining the desired level of decopperization in a shorter time and with lesser quantities of reagents. The autoclave was designed and constructed with a unique oxygen injection system that enables good control of the leaching process and with no plug-ups. Other features include a mass measuring system that balances the quantity of slimes to be leached to the desired final solution concentration based on initial feed concentrations. The end result was a more efficient and controllable leaching process for removing copper from anode slimes.IntroductionThe electrolytic refining of copper consists of an electrolytic cell filled with a sulfiiric acid based electrolyte and pairs of copper anodes and cathodes. When a current is applied, copper in the anode dissolves and is plated onto the cathode. Impurities within the anode that are more noble than copper do not dissolve and end up at the bottom of the cell and are referred to as slimes. Gold and silver are the main slimes constituents of interest because of their monetary value, but there typically are significant quantities of selenium, tellurium, lead, antimony, arsenic, bismuth, nickel, silica and tin. Copper is also present, usually as a metallic or as a reactant with tellurium, selenium, oxygen or sulfur and can range from 10 to 30% of the slimes fall."

Jan 1, 2012

By Jincheng Hu, Honggang Zhong, Qijie Zhai, Congsen Wu, Cheng Zhang, Jingzheng Ye

"The influence of cooling intensity on the solidification structure and ferrite phase content of a new duplex stainless steel (DSS) was investigated by using a thermal simulation setup for continuous casting. The results showed that the characteristics of the solidification structure were similar to their industrial scale manufactured slabs, including chill zone, colunmar zone and equiaxed zone. And austenite morphologies were mainly primary and secondary Widmanstatten sideplates as well as intragranular Widmanstatten plates. In addition, it revealed that the ferrite content increased with an increasing distance from the chill surface and decreased at colunmar to equiaxed transition (CET) position, then the value remained relatively stable at equiaxed zone. Furthermore, the ferrite content presented the same trend with the cooling intensity ranging from 100 mL/min to 2000 mL/min with the values just varying in a slight range.IntroductionThe duplex stainless steel (DSS) is the kind of steel that ferrite phase and austenite phase occupy about 50% respectively, or the content of the fewer phase has to be more than 30% [l]. The success of modem duplex stainless steels is to a large degree due to their higher strength than austenitic stainless steels, higher toughness than ferritic stainless steels, good weldability and high resistance to stress corrosion cracking as well [2,3]. The cost of stainless steel production continues to soar in recent years due to the increasingly higher price of Cr. In order to decrease the production cost, a new type of duplex stainless steel was developed by Bao steel [4]. This newly developed duplex stainless steel had low Cr content compared with 2205 DSS, and was expected to be applied into automobile industry. However, this type of steel was still in the initial stage of development, and the influence of continuous casting process on its solidification process and structure was still unclear, which needed to be studied further. Several works published in literature presented the effect of continuous casting conditions on duplex stainless steel (DSS) 2205, 2304 [5,6]. It was discussed that the cooling intensity in the chill-side had little efficient influence on the phase transformation. In this paper, the effect of cooling intensity on the solidification structure and ferrite volume fraction of this DSS at a given cooling rate was investigated."

Jan 1, 2014

By Toshiyuki Kozuka

CdTe metal composite semi-conducting material has high potential in good performance of energy conversion efficiency for solar cell and there is much room for improvement of the performance by developing a process of making a thin CdTe film. In this paper, the imposition of intense magnetic field on CdTe electro-depositing surface is proposed, which is one of the possibilities for improving the energy conversion efficiency. In the experiment, cryogen-free super-conducting magnet up to 5T was used and CdTe film was deposited electrically in -0.72V vs. SHE The electrolyte was Cd and Te ammonia alkali solution with controlled temperature in the acrylic cell of 70mm diameter. Electro-deposition behavior of CdTe has affected by the imposition of the intense magnetic field due to microscopic convection in the vicinity of the depositing surface. Electro-deposited surface of CdTe becomes smooth due to microscopic convection around the surface, and the crystallization behavior is also affected, where crystallization temperature and the grain size is changed by the imposition of intense magnetic field.

Jan 1, 2003

By P. Felix

A discussion on the need of visualization and animation tools in modelling solidification processes is made. An outline of an approach for the production of a video computer animation is provided. A number of examples including, 2 and 3 dimensional melting, filling, and macrosegregation are presented.

Jan 1, 1993

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 Kenji Morinaga, Shigeru Fujino

"Preparation and vacuum ultraviolet (VUV) transmission spectra of aluminum fluoroberyllate glasses, MgF2-CaF2-SrF2-A1Fr BeF2 (MCSA-Be) and MgF2-CaF2-SrF2-AlFrYFrBeF2 (MCSAY-Be), were studied. The influence of YF3 and BeF2 on the thermal stabilization against crystallization and VUV transmittance was investigated. With increasing the BeF2 content, the crystallization tendency decreased and the absorption edge shifted to shorter wavelength in the MCSA-Be and MCSAY-Be glasses. The MCSA-20Be glass composition exhibited the shortest wavelength UV absorption edge (-147 nm) and the highest transmittance at 157 nm (60% for 2 mm sample thickness). The transmission values at 157 nm and the slope (steepness) of the absorption edge were found to be significantly influenced by the trace amount of Fe2+ derived from the BeF2 raw materials.IntroductionPure beryllium fluoride is known to be an only fluoride that forms one component glass on cooling from the molten state and is structurally similar to silica with [SiO4]4- tetrahedra. Molten BeF2 is highly viscous with a viscosity of about 106 poise near its liquidus temperature at 550""C[l]. The addition of modifying fluorides such as LiF, NaF or KF to BeF2 substantially decreases the viscosity[2]. Glass forming region of binary fluoroberyllate glasses has been mainly reported by several authors [3]. LiFBeF2 binary system is structually analogy for Mg0-Si02 system from their phase diagram and ratio of ionic radius for each cation and anion, respectively. LiF-BeF2 binary glasses seems to be promising candidates for the extreme deep vacuum ultraviolet (VUV) transmitting optical materials owing to their larger band gap. However, it is chemically unstable, and so, have no practical application for lens systems in micro lithography equipments and substrate materials for F2 (157nm) excimer laser[4]. There are also few reports on the VUV transparency of multicomponent aluminium fluoroberyllate glasses from the view point of their compositional dependencies. The purpose of this paper is to prepare deep VUV transmitting optical materials and determine the optimum glass compositions for aluminium fluoroberyllate glasses investigating their thermal stabilization against crystallization."

Jan 1, 2000

By Onuralp Yucel, Ahmet Turan, Halil Yildirim

"Nickel is mainly used in stainless steel production as ferronickel. In recent years, low grade ferronickel or nickel pig iron (NPI) is used in stainless steel production to reduce expenditure of nickel price. In this study, Turkey East Anatolian region lateritic nickel ores were directly introduced carbothermal reduction to produce NPI. Firstly the raw lateritic ore that contains 0.9% Ni, 0.054% Co and 2.3% Cr was mixed with metallurgical grade coal at different stiochometric ratios. The samples were smelted at 1600-1650 °C temperature range in an induction furnace for 25 min. In the second experimental set, different processes times were carried out from 15 to 35 min. The raw material, obtained alloys and slags were analyzed by using XRD (X-Ray Diffractometer), XRF (X-Ray Fluorescence Spectrometer), AAS (Atomic Absorption Spectrometer) and EPMA (Electron Probe Micro Analyzer) techniques.IntroductionNickel is an important element that has many application areas in the industry and there are a lot of kinds of nickel products such as refined metal, powder, sponge etc. 65% of metallic nickel is used in stainless steel, 12% is consumed as superalloy and non ferrous alloy because of its superior corrosion and high temperature properties [1].Nickel is a transition metal that is mined from mainly two types of ore deposits as sulphide ores and lateritic ores. Although 73% of nickel ores are laterites, 55% of primary production is from sulphide ores [1, 2]. The importance of lateritic ores is increasing due to the increase in nickel prices and decrease in reserves of sulphide ores.There are pyrometallurgical, hydrometallurgical and combined (pyro-hydrometallurgical) methods which are used for the extraction of nickel from lateritic ores. HPAL (High temperature pressure acid leaching) is generally used to recover nickel and cobalt from laterite nickel ores. It is suitable for the plants processing ores with low magnesium oxide and aluminum oxide content. Lateritic ores are exposed to hot acidic leaching around ~250 °C to dissolve cobalt and nickel under high pressure. The main disadvantage for HPAL is the high cost of titanium autoclaves. Process is complex and difficult to control due to the high pressure and heating of the process [2, 3 and 4]."

Jan 1, 2012

By Peter Brown

The present work involves the study of Chemical Vapor Deposition (CVD) of silicon carbide from the methyltrichlorosilane (MTS) - hydrogen system. A computer program, SOLGASMIX has been employed to calculate the equilibrium compositions of the gaseous and condensed phases in the MTS - H2 system. The results indicate the range of parameters such as temperature, pressure and species concentrations, required to deposit the single phase Sic under thermodynamic equilibrium conditions. A mathematical model for describing the transport phenomena and the rate of deposition of Sic onto a thin rod in a vertically-oriented hot-walled CVD reactor has been developed. Exper iments were conducted using the same operating conditions as those used in the model in order to validate the mathematical predictions. The predicted rates of deposition were found to be in good agreement with those obtained experimentally. The model can be used to study the effects of various operating parameters on the rate of Sic deposition on a fiber.

Jan 1, 1992

By Terry Mandziak

Typical leach mine operations recover gold values through the application of a dilute cyanide solution onto ore within an engineered facility. Key to the success of mining operations is the, containment and management of the cyanide solutions within the facility. Properly engineered&apos; facilities will have containment systems that are both protective of the environment while enhancing solution recovery. This paper not only discusses general containment standards, but identifies state-of-the-art containment and monitoring practices;

Jan 1, 1998

By Christina V. White

An experimental study was undertaken to investigate the feasibility of utilizing vapor transport for the treatment of heavy metal contaminated smelter soils. The focus of this project was to develop process chemistries that would make incineration a viable process for the treatment these soils. The experimentation concentrated on the elimination of arsenic, cadmium, and lead, and was performed in a laboramry scale rotary kiln setup. Three soil samples from non¬ferrous smelter sites, which contained various concentrations of contaminants, were utilized in the experimentation. Three chemistries were investigated for the volatilization of the heavy metals: Chloridizing volatilization, ferric chloride vapor complex formation, and the use of oxygen potential control. The samples were analyzed for residual heavy metals so that the extractions could be determined. However, the ultimate test was the leachability of the residual arsenic, cadmium, and lead, as determined by the TCLP test. The results firmly establish that incineration is a feasible process for the treatment of metal contaminated soils. It was found that no one process chemistry is suitable for all different soil samples. A two-step process consisting of a reducing step followed by a hydro-chlorination step was required to make Soil Sample-B pass the TCLP tests for all three heavy metals. Soil Sample-A passed the TCLP tests for arsenic, cadmium, and lead using a hydro-chlorination process at a minimum temperature of 700°C. In addition to passing the TCLP mm for Soil Sample-A and Soil Sample-B, 70 to 80 percent removal of the impurities was accomplished. This demonstrates that the leachability of the impurities was decreased primarily due to the removal of a large fraction of the contaminants, Soil Sample-C possessed very high levels of cadmium and lead and only moderate extractions of the impurities were generated from this soil. The arsenic TCLP test was passed at 500&apos;C using a process gas containing ferric chloride and at temperatures of 700°C and above using chlorination of hydro-chlorination.

Jan 1, 1996

By F. J. Hogan

In early 1982 Atlantic Cement Company, a wholly-owned subsidiary of Newmont Mining Corp. will come on line with a new water granulating grinding facility at Sparrows Point, Maryland to produce 800, 000 tons a year of separately ground granulated blast-furnace slag. The process and product will be unique to the United States. This paper will review some initial investigations undertaken to evaluate the cementitious properties of granulated slag. The effect of slag fineness on strength development is discussed and data is presented showing a relationship between glass content and hydraulicity and grindability of slag.

Jan 1, 1982