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By Pengfu Tan

One copper Isasmelt furnace has been operated in Xstrata Copper at Mount Isa in Australia since 1992. A thermodynamic model and computer program, CuModel, has been developed to model the distribution behaviors of Cu, Fe, S, O, Ni, Co, Sn, Pb, Zn, As, Sb, Bi, Au and Ag, copper loss in the slag, and heat balance in copper smelting process, matte converting process and copper continuous smelting process. The thermodynamic model has been used to model the key parameters in the control of the copper Isasmelt furnace. The effects of the process parameters on the control of the copper Isasmelt furnace have been predicted and discussed. These process parameters include SiO2/Fe, matte grade, coal, temperature, spec air of feed, oxygen enrichment, and MgO contents in slag.

Jan 1, 2006

By Qingsheng Liu

A new method of recycling aluminum dross for preparation Al-Si-Ti alloy was studied in this paper. This was carried out in two processes. first the aluminum doss was pretreated by leaching and calcining process, the fine purity and phase of the intermediate oxide powder up to electrolysis demands, then, could be obtained when aluminum dross after washing have been leached for 2h at 100? in 20% hydrochloric acid and calcined for 2h at 1200?, which was treated by cryoite-based molten salt electrolysis. Finally, the Al-Si-Ti alloy was successfully obtained through electrochemical co-deposition in the cathode shows a typical as-cast microstructure. This new recycling method can produce high quality alloy and may bring remarkable economic and social benefits.

Jan 1, 2010

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 Taegong Ryu

Nanosized tungsten powder was synthesized by the hydrogen reduction of ammonium paratungstate (APT) in thermal plasma. The effects of operating conditions on the product composition and particle size were investigated. The particle size of synthesized W powder was less than 30 nm in all cases tested. The sintering behavior of the synthesized powder (25 nm average size) was then investigated and compared with those of commercial W powder of 500 nm average size and W powder of 23 nm average size produced by milling the commercial powder. The sintering was done at 1400oC with various holding times. The hardness of the resulting compact from the synthesized W powder (315 VHN) was similar to that from the milled W powder (309 VHN), but the plasma-synthesized powder had a much lower tendency to form cracks. The compacts of both nanopowders were significantly harder than that of the commercial powder (192 VHN).

Jan 1, 2009

By Wellington Pereira Inácio

This work investigated the toughness behavior of polyester matrix composites reinforced with up to 30% in volume of long, continuous and aligned sisal fibers by means of Charpy impact tests. It was found that the addition of sisal fibers results in a marked increase in the absorbed impact energy of the composites. Macroscopic observation of the post-impact specimens and SEM fracture analysis showed that longitudinal rupture through the sisal fiber interface with the polyester matrix is the main mechanism for the remarkable toughness of these composites.

Jan 1, 2010

By Xi Zhang

A technique for fabricating free-standing, high-aspect-ratio porous and pillar-type Ni structures has been developed using wet Si processing. A wafer of (100) Si was initially etched in HF solution to form deep pores with micron-sized diameter. The aspect ratio can exceed 200. By introducing the as-etched Si into a defined aqueous Ni2+ solution, Ni deposits grew rapidly onto the sidewalls and replaced the Si. Long-time immersion allows the Si sidewalls to be completely converted and thus form a metallic Ni structure with high-aspect-ratio pores. It is known that close-packed submicron Si pillars can be formed by oxidizing and subsequent etching of the macropore sidewalls. Treated in the same Ni solution, high-aspect-ratio Ni pillars were correspondingly emerged by replicating the original pillar-type Si structure.

Jan 1, 2006

By M. T. Baquera

A comparison of microstructures associated with W single-crystal ([001], [011], [111]) rods prior to deformation (as grown), and after quasi-static compression (at a strain rate of ~1/s) by transmission electron microscopy (TEM) shows several orders of magnitude difference in dislocation density. Dislocation substructures were not significantly different amongst the deformed sample orientations. In contrast, [001] W rods penetrated into steel targets, at impact velocities of ~1.3 km/s, exhibited heavy dislocation densities and dynamic recrystallization as very distinct microstructural regimes accommodating the penetration process. Twinning on {112} also occurred as a precursor to, or remnant of, these microstructures near the projectile head. These results suggest that deformation accommodating the extreme strains and strain rates associated with the penetration of a single-crystal rod into a metal target is not adequately represented by conventional deformation

Jan 1, 2006

By Tian Sugui

By direct aging treated, creep properties measurement and microstructure observation, the influences of the direct aging treatment on the creep behaviors of Hot Continuous Rolled GH4169 superalloy are investigated. Results show that the creep resistance of Hot Continuous Rolled GH4169 superalloy may be obviously improved by directly aged treatment. Under the applied stress of 700MPa at 660, the creep lifetime of the alloy is enhanced to 126h from 60h. During hot continuous rolling, the deformation features of the alloy are the twinning and the double orientations slipping of the dislocation activated within the twinning regions. After direct aging treated, the alloy displays a smaller grain size, and the finer g² phase is dispersedly precipitated in the matrix of the alloy, which is thought to be a main reason of enhancing creep lifetime of the alloy.

Jan 1, 2010

By Meghan McGrath

Third generation advance high strength steels with microstructures of acicular ferrite and retained austenite were investigated and meet mechanical property goals. A good combination of strength and ductility were achieved with duplex ferrite and austenite microstructures where cementite formation was suppressed. Transformation induced plasticity (TRIP) behavior produced rapid work hardening. The mechanical properties of two hot-rolled steels with duplex microstructures were compared and had the following compositions: (1) Fe-0.14C-13.87Mn-1.42Si-3.51Al; and (2) Fe-0.06C-14.2Mn-1.85Si-2.38Al. These steels were cast, homogenized, and hot rolled at 900ºC to obtain a refined microstructure with ultimate tensile strengths and elongations to failure of 865 MPa and 39% and 1,217 MPa and 28%, respectively. The amount of metastable austenite in both compositions decreased after tensile testing from 58% and 28% to 6% and 0%, respectively. Microstructures were characterized using optical microscopy, scanning electron microscopy (SEM), and x-ray diffraction.

Jan 1, 2010

By S. B. Johnson

Keywords: Spray, Aluminum, Simulation A stochastic, droplet-resolved model has been developed to describe the behavior of a binary aluminum alloy spray during the spray-rolling process. In this process, a molten aluminum alloy is atomized and the resulting spray is deposited on the rolls of a twin-roll caster to produce aluminum strip. The one-way coupled spray model allows the prediction of spray characteristics such as enthalpy and solid fraction, and their distribution between the nozzle and the deposition surface. This paper outlines the model development and compares the predicted spray dynamics to PDI measurements performed in a controlled configuration. Predicted and measured droplet velocity and size distributions are presented for two points along the spray centerline along with predicted spray averaged specific enthalpy and solid fraction curves.

Jan 1, 2005

By Igor Zh. Bunin

A model for developing electric discharges between sulfide mineral (pyrite) particles under high-voltage nanosecond pulses in a liquid medium (water) is considered. A possibility of electrical breakdowns of liquid gaps between particles under nanosecond pulses is shown. This probability and the energy released in discharge channels depend strongly on the sulfide conductivity.

Jan 1, 2010

By Andrey V. Tarasov

To carry out a physicochemical substantiation of a transition to ?soft? modes of reduction of calcine obtained by desulfurizing roasting of nickel concentrate produced as a result of copper-nickel converter matte separation in a nickel anode production circuit, an analysis has been conducted of the macrokinetic behavior of actual calcine samples in the presence of gaseous H2-CO mixtures and solid reductant additives. Within a temperature range of 900°C to 1100°C the main regularities typical of the calcine reduction process with individual gases (H2, CO) also take place when using a gaseous mixture. Under the conditions of low-temperature (900°C to 1000°C) nickel oxide reduction with products of fuel oil conversion in the presence of coke, the role of the latter is insignificant from the technological viewpoint. As a result of the present investigations, we have obtained analytical expressions of macrokinetic parameters of the reaction interaction within the [NiO] calcine-H2-CO-C-CO2-H2O-O2-N2 system.

Jan 1, 2005

By Fanke Meng

Electrolyzing oxides of titanium, aluminum and niobium could prepare high-Nb bearing TiAl alloy (Ti-45Al-9Nb) at 1500°C. The chosen electrolysis voltage is 3.5V, which is lower than reducing voltage (~4.7V) of electrolyte CaF2, but higher than that of titanium, aluminum and niobium oxides. The investigation shows that compared with traditional methods, this method for preparing high-Nb bearing TiAl alloy is of many advantages such as few steps, friendly environment, low energy consumption, low cost and high current efficiency.

Jan 1, 2009

By David Norval

Ni, Co, Cu and Pt, mattes are common materials that require granulating and milling of the resultant granules for further processing. This route is acceptable if the material is brittle (friable) which is a property associated with the higher sulphur mattes. For lower sulphur levels, where the matte is less amenable to milling, the costs of the milling increases. This paper will compare water granulation with certain dry granulation processes and the downstream processes required for Hydrometallurgy. It will further introduce and expand on atomisation which offers a further safety benefit in the control of the metal flow into the 'wet zone' with the use of a tundish flow control also reducing the conversion from the matte to powder in one fairly straightforward operation.

Jan 1, 2006

By Natalya. N. Ankusheva

The problems of ore-bearing palaevolcanic structures in folded belts are actual because of their high productivity in nonferrous, ferrous and noble metals ores. Now relationships of location and conditions of formation for sulfide-massive and gold-bearing deposits are investigated very well in Urals. But carboniferous sulfide-barite mineralization, for example the barite veins in Arcaimsky palaevolcano are?nt studied enough now [3-5]. The purpose of this research is the studying of mineralogy and thermobarogeochemistry of barite from the hydrothermal veins. It will allow to determine the conditions of its formation and to compare it to the similar mineralization of others ore types.

Jan 1, 2006

By Felipe Perissé Duarte Lopes

The tensile properties of DGEBA/TETA epoxy matrix composites reinforced with different amounts of curaua fibers were evaluated. Tensile specimens with up to 35% in volume of long, continuous and aligned curaua fibers were room temperature tested in an Instron machine. The fracture was analyzed by SEM. The results showed significant changes in the mechanical properties with the amount of curaua fibers. This was compared to other bend-tested composites with distinct matrices. The fracture analysis revealed a weak fiber/matrix interface, which could be responsible for the comparatively low performance of some properties.

Jan 1, 2010

By Jewel A. G. Gomes

Electrocoagulation (EC) has been performed with Al-Fe electrode system with changing polarity for the removal of arsenic from water. The removal process has been studied using ICP-AES and Anodic Stripping Voltammetry with a wide range of arsenic concentration (1-1000 ppm) at various pH (4-10) and residence times (1-60 min). Electrochemically generated by-products have been analyzed using XRD, FTIR, XPS, SEM/EDS and Mössbauer Spectroscopy. Results revealed expected crystalline iron oxides (magnetite (Fe3O4), lepidocrocite (FeO(OH)), iron oxide (FeO)) and aluminum oxides (bayerite (Al(OH)3), diaspore (AlO(OH)), mansfieldite (AlAsO4?2(H2O)), as well as some interaction between the phases. The amorphous or ultra-fine particular phase was also found in the floc. The substitution of Fe3+ ions by Al3+ ions in the solid surface has been observed, indicating an alternative removal mechanism of arsenic in these metal hydroxides and oxyhydroxides by providing larger surface area for arsenic adsorption via retarding the crystalline formation of iron oxides.

Jan 1, 2006

By Sergio N. Monteiro

Natural lignocellulosic fibers are successfully replacing synthetic fibers in many engineering applications. In addition to well-known conventional lignocellulosic fibers, others with promising properties are now being considered. The present work investigated the mechanical and structural characteristics of a relatively high strength fiber, curaua (Ananas erectifolius) from the Amazon region of Brazil. The results obtained from tensile tests confirmed the superior strength while scanning electron microscopy (SEM) analysis displayed features that justify the possibility of using the curaua fiber as an effective reinforcement for polymeric composites.

Jan 1, 2006

By Youze Xu

The leaching and reduction of Cr(VI) in soils contaminated by chromium-containing slag were investigated with column experiments. The results showed that Cr(VI) concentration in leachate decreased from 988 mg L-1 to 407 mg L-1 after 7 days when water was used as leaching agent. However, Cr(VI) in leachate in culture medium treatment was not detected at above periods. In comparison, Cr(VI) concentration in leachate from autoclaved soil remained 398 mg L-1 at the end of experiment. The results indicated that the indigenous microorganism was capable of reducing Cr(VI). The amount of Cr(VI) reduction was 335 mg at the whole experiment period and the reduction rate was 67.09 mg d-1. Carbon supply showed minor effect on Cr(VI) reduction. However the reduction capability of Cr(VI) could be improved by combination of the carbon and the nitrogen. The optimal quantity was 5 g L-1 of yeast extract and 4 g L-1 of glucose.

Jan 1, 2009

By Sergio Neves Monteiro

The efficiency by which an applied load is transmitted through the composite structure depends on the strength of the interface between the matrix and the second phase. In fiber reinforced composites, the interfacial shear stress plays a major role in the composite capacity to support the applied load. This interfacial stress can be obtained by means of pullout tests using the fiber embedded to a certain length in a socket of the matrix material. In the present work, pullout tests were performed to evaluate the interfacial shear stress of ramie, a relatively strong natural fiber, reinforcing polyester matrix composites. The general result permitted to calculate a critical length for the ramie fiber embedded in polyester resin. From this critical length, the value of the interfacial shear stress was calculated. An interpretation of this result together with SEM observation displayed a relatively weak bond between the ramie fiber and the polyester matrix.

Jan 1, 2010