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By Xuan Li

Aluminum slag is generated when aluminum metals are recycled through a smelting process in the presence of salt. There are small amounts of aluminum metals trapped in the aluminum slag. This research aims at evaluating the use of aluminum slag as an expansion agent for the production of lightweight concrete by taking advantage of the residual aluminum metals in the slag. The research identified key elements of producing lightweight concrete products through utilizing various mixture components including sodium hydroxide (NaOH), lime (CaO), cement, and gypsum. The volumetric expansion rate was investigated and the density and strength of the products were determined. The results show that aluminum slag can be utilized for the production of lightweight concrete products.

Jan 1, 2010

By Jilai Xue

Fe-Ni alloys can be used as raw material in making stainless steel. Laterite nickel ore is one of mineral resources for producing nickel alloys. In this work, the laterite ore after dehydration at 800 °C and the anthracite as reducing agent were mixed for pre-reduction at 900 °C, and then reduced to form Fe-Ni alloys at 1550-1620 °C through carbon-thermal reduction process. A high Ni-content alloy component in the metallurgical mixture can be formed through pre-reduction. Better separation of the resulting metals from the slag is found with lower Ni-content alloys produced or higher temperatures during reduction. An effective processing of Fe-Ni alloys needs further understanding of the process fundamentals and optimizing of the process parameters.

Jan 1, 2010

By L. R. Verney

About 75% of the market economy countries's supply of cobalt is produced in Central Africa by Zafre and Zambia. Zafre alone accounts for more than 55% and has the resources and capacity to increase output significantly at any time so its dominant position is unlikely to be challenged in the foreseeable future. Other producers from domestic resources are Canada, Australia and South Africa; and Cuba, probably the most important producer outside of the Market Economy countries. Belgium, Norway, France, Japan and Finland produce cobalt from imported materials. While there are "cobalt ores", inMorocco, USA, Canada and the USSR, the mineralisation is complex and cobalt extraction is costly. In ZaPre and Zambia cobalt is a by-product of copper; in Canada, Australia, France, and Cuba it is a by-product of nickel; and in South Africa it is a by-product from the production of Platinum Group Metals. Thus the levels of cobalt production are inevitably related to the production of other primary metals. While some cobalt is produced by predominantly pyrometallurgical methods most of the world's cobalt is produced hydrometallurgically. The existence of large hydro-electric power plants and the mineralogy of the copper and cobalt concentrates encouraged research and development in Zafre of the recovery of copper and cobalt by electrowinning from sulfate solutions; much pioneering work was carried out, which lead to construction of the two largest copperlcobalt hydrometallurgical plants in the world, at Shituru and Luilu. Similar systems were adopted in Zambia. In Canada high pressure hydrometallurgical processes based on the sulfate system were developed and adopted in Australia, the Philippines, Finland and South Africa. Meanwhile developments in chloride hydrometallurgical extraction of nickel and cobalt lead to its use in the extraction of cobalt in Norway, France and Japan.

Jan 1, 1988

A modified Cuprex Metal Extraction Process (CMEP) leach process was used to extract Cu. Ni and Co from a complex sulphide concentrate. The standard leach was modified to a two-stage countercurrent leach which provided emf control of the copper SX feed and minimized iron dissolution. A flowsheet was developed to recover the base metals and silver from the leach solution and gold and platinum group metals from the leach residue which was predominantly elemental sulphur. Techniques required to maintain an iron balance in the system including pressure oxidation and solvent extraction are described.

Jan 1, 1996

By Pengfu Tan

A thermodynamic model has been developed to predict the distribution behaviors of Cu, Fe, S, O, Pb, Zn, As, and heat balance in a lead blast furnace. The modeling results have been validated by the plant data of a lead smelter in Asia. The model can be used to predict for any set of controllable process parameters such as feed composition, smelting temperature, degree of oxygen enrichment and volume of oxygen-enriched air. The effects of the blast air, industrial oxygen, and coke charge on the distributions of Cu, Fe, S, O, Pb, Zn, As, and heat balance, and on the lead loss in slag have been presented and discussed.

Jan 1, 2005

By Cem Colakoglu

In this study, nickel containing iron alloys were produced by carbothermal reduction of lateritic nickel ores obtained from Manisa - Caldag region of Turkiye in order to investigate the reaction mechanism of nickel and cobalt. In the experiments, the lateritic ore containing 1.58 wt.% Ni and 0.12 wt.% Co was calcined in a semi-pilot scale rotary furnace at 1100°C for 1 hour. Then, a mixture of calcined ore and metallurgical coke was reacted in sintered alumina crucibles using a graphite resistance tube furnace at different time (0- 60 min) and temperature (1500-1600°C).

Jan 1, 2009

By Nobuaki Sato

For the recovery of uranium from spent nuclear fuel, sulfide reprocessing process, which consists of voloxidation, selective sulfurization, and magnetic separation or selective dissolution steps, are proposed. In this paper selective sulfurization of rare-earth oxides in the presence of uranium oxides was studied by thermogravimetry and X-ray diffractometry. In case of the mixture with UO2, the rare earth oxides R2O3 (R=Nd, Eu, etc.) were preferentially sulfurized by CS2 formingoxysulfides and sulfides, while UO2 remained at temperatures lower than 500 °C. When R2O3was mixed with U3O8, first, the reduction of U3O8 to UO2 occurred at low temperatures followed by the sulfurization of R2O3. The separation of rare earth elements from UO2 in suspensionsolution by the use of permanent magnet was examined. The advantage of the proposed process was also discussed by compared with current process.

Jan 1, 2006

By A. L. D. Skury

In the synthesis of diamond, the precursor graphite must present a degree of crystallinity to assure optimum yield and quality for the transformed crystals. X-ray diffraction, SEM and TEM analyses were carried out to investigate the structural and morphologic transformations produced in natural graphite by high pressure-high temperature treatment. The present study had as its objective to characterize the morphological and structural changes suffered by a natural graphite that was subjected to high pressure and high temperature treatments in the region of diamond thermodynamic stability. The results indicate that the material that constitutes the gasket, for the deformable capsule, could act as catalyst in the graphite recrystallization process.

Jan 1, 2006

By Hector Carreon

Due to elevated temperatures, excessive stresses and severed corrosion conditions, turbine engine components are subject to creep processes that limit the components life such as a turbine bucket. The failure mechanism of a turbine bucket is related primarily to creep and corrosion and secondarily to thermal fatigue. As a result, it is desirable to assess the current condition of such turbine component. By using eddy current images, it was shown that the eddy current technique could be used to monitor creep damage in a nickel base super-alloy. The eddy current results also show a significative variation in the electrical conductivity on the creep damage zone with respect to the background zone in nickel-base super-alloy samples. In addition, the absolute thermoelectric power coefficient show also a strong dependence associated with creep damage in nickel base super-alloy samples using a copper hot tip reference. The eddy current and thermoelectric power techniques seems to show promise as nondestructive evaluation tools for monitoring the level of creep damage in metallic alloys.

Jan 1, 2010

By C. E. M. Meskers

End-of-life Electronic and Electrical Equipment, o_cially called WEEE, is unjustly regarded as mainly a waste management problem. What is structurally overlooked is the enormous resource impact of these devices. EEE rep- resents a tremendous metal resource, which should be uti- lized through e_ective recycling, which has a much lower environmental footprint than primary production. The actual amount of end-of-life EEE recycled today is embar- rassingly low since insu_cient EEE is collected and part of the collected EEE is exported to developing countries, where it is largely not entering o_cial recycling systems. To achieve a global recycling society issues like technol- ogy, economics, life cycle structure, stakeholder aware- ness and legislation have to be addressed in a global, co-operative manner so that sustainable closed product cycles can be obtained. Requirements for a "global re- cycling society" are de_ned to address today's reality of global ows of used consumer products, taking into ac- count the likely needs of the future.

Jan 1, 2009

By Bowen Li

Silicon Carbide is an excellent refractory material. Its physical properties make it extremely useful, particularly in applications where corrosion resistance and wear are important considerations. Commercial silicon carbide refractory is frequently manufactured by bonding silicon carbide particles with clay; however, clay may cause problems in the sintered products. This study investigates the potential of replacing a portion of the clay with andalusite powder. The results show that micron size andalusite powder can improve not only the strength of the refractory but also the sinterability. The mechanisms for these improvements are discussed.

Jan 1, 2006

By S. Y. Tan

The thermal stability of fully silicided NiSi with arsenic doping on silicon was investigated. The aims of the work were to investigate the Ni silicide phase-related issues associated with arsenic dopant and thermal annealing on Ni-FUSI/HfO2/Si and Ni-FUSI/HfSiO/Si gate stacks. It was found that arsenic-incorporation demonstrated some improvement in both morphology and phase stability of nickel silicided films at high processing temperatures regardless underlying gate dielectrics. The correlations of Ni-Si phase transformation and arsenic doapnt with their electrical and physical changes were established by sheet resistance measurements, X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) analysis. Furthermore, the modulation of the work function (WF) of Ni fully silicided gates by arsenic impurity is presented, comparing the effects of dopant (As) on the WF and silicide phases (NiSi and NiSi2). It confirmed that the work function of NiSi can be tuned by implanting arsenic dopant, but it ineffective for NiSi2 phase.

Jan 1, 2010

A three?stages countercurrent fluidized bed prototipe reactor to neutralize the SO2from smelter gases has been developed. For gases with 8 vol-%SO2, at 800°C and for 4 h mean reaction time of the limestone, the capture of SO2 is 99%, with off gases with 0.07 vol-%. For 2 vol-%SO2, the total capture of SO2 can be obtained at 750°C and 4 h reaction time. The calcine obtained contain a blend of unreacted limestone and calcium sulphatewith minor amounts of residual lime.

Jan 1, 2006

By Xiaowen Liu

The DSC/TG, IR and XRD analysis were used to characterize the heating phase transformation of illite, which came from Ouhai deposit, China. It was discovered that the dehydration and de-hydroxylation of illite carried out stage by stage during heating. The adsorptive water and layer-inter water were dehydrated from room temperature to 500°C; and dehydroxylated in the range 500°C~800°C. In these stages of process, illite?s layer structure kept almost unchanged. After 800°Cillite began to change into disorder structure. At about 1100°C, the layer structure of illite had been destroyed, and amorphous SiO2 and mullite crystallite appeared. At about 1200°C the structure of illite completely destroyed and mullite crystal phase had become perfect..

Jan 1, 2006

By Bowen Li

Andalusite is an excellent raw material for refractory applications due to its high aluminum oxide content and phase transformation to mullite at high temperature. Granular andalusite in particle sizes of about 1 to 2 mm was traditionally utilized for the manufacturing of refractory brick. However, if powder andalusite in micron particle size is utilized in high-alumina refractory products, reinforcement on the refractory brick can be obtained and the sintering temperature can be decreased. The phase transformation of powder andalusite plays a key role for the difference.

Jan 1, 2006

By Ramona Prillhofer

Salt slag is a waste product produced by the recycling of aluminum. In most European countries (e.g. Austria, Germany) the landfill disposal of this waste is forbidden because the slag contains soluble salts and these represent a potential source of pollution to the surface and groundwater. Additionally, consisting metal and some compounds in the salt slag can react with water and resulting from this, noxious gases are generated. The recovery of useful materials from these wastes is accordingly both environmentally necessary and economically feasible. This study describes a complete recycling-process for the salt slag, which includes a leaching-cristallization-process to obtain the oxidic residue, a pyrometallurgical-step to clear the oxidic residue and finally an extensive characterization of the achieved products. Due to the increasing price of raw materials, the utilization of the oxidic residue into commercial products has been investigated and application possibilities will be discussed.

Jan 1, 2009

By Varadajan Seshadri

Keywords: torpedo car, kinetics, physical modeling A 1:6 torpedo car physical model was built to assess the optimum refining conditions for pig iron desulfurization in the torpedo car considering the industrial parameters used in the steel plant CSBM (Companhia Siderurgica Belgo-Mineira, João Monlevade, MG, Brazil). The refining practice in this plant is through injection of a CaO-CaF2-Mg powder in the pig iron melt. 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 were also evaluated.

Jan 1, 2005

By Huang Kai

By adding the solid oxalate acid powder into the solution of nickel chloride or its ammonia coordinated solution, the uniform compound particles were prepared and the precipitated particles were transferred to the mono-dispersed NiO particles by calcination. In this study, the various experimental conditions were investigated, the characteristics of the corresponding obtained particles were analyzed, and the formation mechanism of the particles was elucidated. It was found that the solid oxalate acid provided the solid-solution interface for the precipitation and induced the nucleation and growth of the product particles.

Jan 1, 2005

By M. Bilal Khan

Thermal stress relief by means of a typical heat treatment cycle (660oC for one hr) is compared with the one achieved through vibratory stress relief at resonant and multiple resonant frequencies for the D-406 HSLA material. Our analysis of the data is based on the microhardness profiles measured for the entire length of scales, namely, base metal, heat affected zone (HAZ) and the weld bead itself. The profiles obtained using the two techniques mimic each other, for an equivalent 70% stress relief level. The data are further qualified by impact testing wherein the zone of interest is projected in the retention groove to provide impact by the pendulum striker in the Charpy mode. Higher equivalent energy absorption in the treated specimens confirms the efficacy of the vibratory method. The present work rectifies earlier anomaly where heat treatment has been reported at 310oC for the same material.

Jan 1, 2009

By Sadegh Firoozi

Experiments measuring the kinetics of oxidation and making visual observations of the oxidation of approximately 6 g static lead baths containing arsenic, antimony and tin were conducted in the temperature range from 500 to 600 oC. A range of repeatable behaviours were observed, notably: the formation of a coherent, solid oxide layers on pure lead and lead-tin alloys; the formation of liquid oxide droplets during the initial oxidation of lead-arsenic and lead-antimony alloys and the eventual formation of a complete oxide layer covering the entire free surface of these alloys. Thermogravimetric measurements revealed that the rate of oxygen uptake was strongly influenced by the form of oxides being generated at the melt/gas interface. Compared to the rates of oxidation of pure lead, arsenic increased the rate of oxygen uptake throughout the temperature range via the formation of liquid oxidation products. The presence of antimony resulted in a moderate increase in the rate of oxygen uptake as compared to arsenic. Tin was effective in lowering the rate of oxidation even in the presence of arsenic because the oxidation product was always a coherent layer that acted as a physical barrier to oxygen transport to the underlying alloy.

Jan 1, 2006