Mixing Furnace Research Articles

Numerical simulation of liquid aluminum leakage in casting process

Abstract A model was built to simulate liquid aluminum leakage during the casting process, including transient trough flow, orifice outflow, and spread, to prevent the explosion. A comparison between the simulation data and the theoretical calculation results verifies that the model has remarkable adaptability and high accuracy. Although the height of liquid aluminum in the mixing furnace and outlet radius are changed, the molten aluminum will not leak during the casting process. The aluminum in the trough moves forward in a wave-like motion and causes a leakage. The spread of the leaked aluminum resembles a long strip on the ground. The leakage amount and spread area of liquid aluminum increase with increasing the height of liquid aluminum in the mixing furnace.

Grain Growth Studies of Indium Antimonide Thin Films and Its Application in photovoltaic cell

Compound III-V materials are formed when atoms from group Illb of the periodic table combine with atoms from group Vb. The resulting com pounds are both crystalline and semiconducting and contain an equal proportion of both atom types. The Indium antimonide crystal has been used for infrared applications and for the radiation detector applications. Thin films of InSb with a thickness of about 0.12 micrometer are prepared onto well-cleaned glass substrates by employing an e- beam evaporation process. Indium Antimonide thin films are grown onto well cleaned glass substrates at room temperature on cleaned glass substrate in Hind Hivac- Vacuum Coating unit under a vacuum better than 10<sup>−5</sup> Torr. X-ray diffraction studies confirm the polycrystalline of the films and the films show preferential orientation along the (111) plane. The particle size found to about 1100 micrometer of thin film. In this paper we present some of our results concerning the synthesis and crystal growth of indium antimonide compounds . To carry out the synthesis of InSb a suitable mixing furnace was designed and fabricated.

Experimental smelting of iron ores from Elba Island (Tuscany, Italy): Results and implications for the reconstruction of ancient metallurgical processes and iron provenance

Iron deposits from Elba Island (Tuscan Archipelago) were extensively exploited since the 1st millennium BC: both raw iron ore and smelted blooms were extensively traded through the Mediterranean region. Within the frame of the multidisciplinary research Project “AITHALE” (from the Greek name for Elba Island), we have performed a series of archaeometallurgical experiments primarily to investigate the traceability of Elban iron ores during the various steps of the chaîne opératoire of bloomery iron production. Results of experiments performed both in the field (reconstruction of a bloomery furnace) and in the laboratory (smelting experiments carried out in a gas mixing furnace) are discussed in the text. Slags produced by smelting of W-Sn-rich iron (hematite) ores, like those from Elba island, show the presence of these elements in phases of their own, either relic (scheelite, ferberite, cassiterite) and/or newly formed (iron-tin alloys). Iron bloom obtained from this kind of iron ore could also bear evidence of the peculiar geochemistry of smelted ore, with tungsten preferentially associated with slag inclusions and tin eventually enriched in the metallic phase.

The whole-block approach to measuring hydrogen diffusivity in nominally anhydrous minerals

A method is developed for determining the diffusivity of infrared-active species by transmission Fourier transform infrared spectroscopy (FTIR) in samples prepared as rectangular prisms without cutting the sample. The primary application of this “whole-block” or “3D-WB” method is in measuring the diffusion of hydrogen (colloquially referred to as “water”) in nominally anhydrous minerals, but the approach is applicable to any IR-active species. The whole-block method requires developing a three-dimensional model that includes the integration of the beam signal through the sample, from rim to core to opposite rim. The analysis is carried out using both forward and tomographic inverse modeling techniques. Measurements collected from central slices cut from the whole block are simpler to interpret than whole-block measurements, but slicing requires destructive sample analysis. Because the whole-block method is nondestructive, this approach allows a time-series of diffusion experiments on the same sample. The potential pitfalls of evaluating whole-block measurements without correcting for path integration effects are explored using simulations. The simulations demonstrate that diffusivities determined from whole-block measurements without considering path-averaging may be up to half an order of magnitude too fast. The largest errors are in fast and/or short directions, in which the diffusion profiles are best developed. A key characteristic of whole-block measurements is that the central values in whole-block traverses always change before the concentration of the IR-active species changes in the block’s center because of signal integration that includes concentrations in the sample rims. The resulting plateau in the measurements is difficult to fit correctly without considering path integration effects, ideally by using 3D whole-block models. However, for early stages of diffusion with <50% progress, diffusivities can be accurately determined within 0.5 log units using a 1D approximation and the whole-block central plateau values because diffusivities are more dependent on profile shape than absolute concentrations. To test the whole-block method, a dehydration experiment was performed on an oriented piece of diopside from the Kunlun Mts with minimal zoning, cracks, or inclusions. The experiment was performed in a gas mixing furnace for 3 days at a temperature of 1000 °C and oxygen fugacity of 10−11.1 bar (QFM). First, whole-block analysis was performed by taking FTIR traverses in three orthogonal directions. Then, a slice was cut from the center of the sample, and hydrogen profiles were measured by FTIR and secondary ion mass spectrometry (SIMS). The results of FTIR and SIMS measurements on the slice are in good agreement both with each other and with diffusion profiles calculated based on the results of forward and inverse models of the whole-block FTIR measurements. Finally, the new method is applied to previous whole-block measurements of hydrogen diffusion in San Carlos olivine using both the forward and inverse approaches.

Phase equilibrium investigations of the Adirondack class basalts from the Gusev plains, Gusev crater, Mars

Abstract— Phase equilibrium experiments have been performed on a synthetic analog of the Gusev plains basalt composition from the Spirit landing site on Mars. Near‐liquidus phase relations were determined over the pressure range of 0.1 to 1.5 GPa and at temperatures from 1125 to 1390 °C in a piston cylinder apparatus and 1 atm gas mixing furnace. The composition is multiply saturated with olivine, orthopyroxene, and spinel near its liquidus at 1320 °C and 1.0 GPa, or 85 km depth on Mars, placing an upper limit constraint on the thickness of the Martian lithosphere at the time of eruption. Our experimental work suggests that the Gusev basalts are anhydrous batch melts of a primitive Martian mantle similar to the composition estimated by Dreibus and Wänke (1984). The temperature of multiple saturation indicates the persistence of high mantle potential temperatures on Mars, similar to those on the modern Earth, until at least the very latest Noachian (3.7 Ga). These high mantle temperatures would be responsible for persistent basaltic volcanism throughout the southern highlands during the first billion years of Mars's history. The source for Gusev basalts differs strongly from the source for shergottite meteorites, reinforcing the idea of the absence of global mantle convection and mixing on Mars. The existence of a relatively primitive mantle reservoir requires that at least part of the mantle underwent little modification during early planetary differentiation.

The connection between high K melts and Au deposits: Evidence from natural and experimental systems

It has long been suspected that K-enriched melts are efficient carriers of Au. This assumption is the result of clear spatial/temporal associations between Au deposits and High-K (or shoshonitic) intrusives in the deposits of Lihir Island (Muller et al., 2001), Bajo de la Alumbrera, Argentina (Muler and Forrestal, 1998), Quesnilla, BC, Canada (Barrie, 1993) and in the Lower Yangtze region of China (Zhou et al., 1996) and others. However, no direct link has been made between the high K nature of these melts and their Au endowment. As a test of this hypothesis, we analysed Au by LA-ICPMS in clinopyroxene-hosted melt inclusions from an ore-associated dyke at the Masbate Gold Deposit in the Phillipines. Pyroxenes were re-equilibrated at 1100 C for 24 h in a controlled gas mixing furnace, quenched in water and polished to expose glassy, homogenised ultrapotassic (8–11wt% K2O) inclusions. All inclusions analysed contain high levels of dissolved gold (up to 20 ppm Au). To independently test this empirical link, we equilibrated hydrous rhyolitic glasses of variable K contents (plus either FeS or FeS and NaCl) with Au capsules in internally-heated pressure vessels. At constant water content, temperature, pressure, fO2 (controlled by H–Ar mixtures) the addition of K2O increases Au solubility by nearly an order of magnitude. In runs with FeS only, Au content increased from 0.08 ppm Au (@1.6% K2O) to 0.66 ppm Au (@ 6.8%K2O), while those with FeS and NaCl contained 0.45 ppm @ 1.6% K2O and 2.2 ppm Au @ 6.1%K2O. These analyses and experiments do not explain the mechanism for increased Au solubility, but they do strengthen the link. Furthermore, in terranes where pervasive alterration obscures primary igneous compositions, melt inclusions may provide the best information, and may provide a valuable exploration tool. References Barrie, C.T., 1993. J. Geochem. Expl. 48, 225–258. Muller, D., Franz, L., Herzig, P.M., Hunt, S., 2001. Lithos 57, 163–186. Muler, D., Forrestal, P., 1998. Min. Pet. 64, 47–64. Zhou, J.C., Zhou, J.P., Liu, J., Zhao, T.P., Chen, W., 1996. J. Geochem. Expl. 57, 273–283. doi:10.1016/j.gca.2006.06.815 A404 Goldschmidt Conference Abstracts 2006

Experimental techniques to minimize Fe and Na losses in one atmosphere gas mixing furnace.

Experimental techniques to minimize loss of iron and sodium from sample materials in experiment using one atmosphere gas mixing furnace are proposed. Melting experiments for basaltic synthetic materials and natural basalts and andesites were carried out at 1150∼1250°C and oxygen fugacities from air to ΔNNO=−5.0. Based on the results of present experiments and previous works, the folowing empirical relationships were derived. Relationship between iron content of platinum loop (XFeFePt alloy) and FeO contenlt in silicate liquid (XTotal FeOLiquid) was described by XFeFePt alloy(wt%)=(1.782-0.0908XTotal FeOLiquid(wt%))logfO2+0.2574logfO22 (1).Correlation among Na2O loss from liquid (Y) and oxygen fugacity, run duration (t), mass of liquid (W), temperature (T) and chemical composition was described by ln[−ln(1−Y(%)/100)]=18.66+2.145×(FeO+MnO+MgO+CaO)/SiO2(mole ratio) −0.225ln fO2−416800/RT(K)−1/3×lnW(mg)+lnt(min) (2). Melting experiments using iron-plated platinum loop whose iron content was calculated from equation (1) and setting Na2SiO3 liquid below the sample were also performed. Loss of FeO and Na2O from sample materials could be reduced considerably by the iron-plated platinum loop and Na2SiO3 liquid. In experiments of iron partitioning in alkaline rich system at reducing oxygen fugacity, continuous change of bulk chemical composition and disequilibrium can be minimized by these techniques.

The sulfur vapor pressure over pyrite on the surface of Venus

The total pressure and molecular speciation of sulfur vapor (dominantly S 2) over pyrite at Venus surface temperatures (≈ 390–470°C) are important for modeling atmospheric chemistry and geochemistry of sulfur gases and minerals on Venus. The sulfur vapor pressure over pyrite in CO 2 and CO 2 gas mixtures, which are relevant to Venus, has not been previously measured. Instead, previous measurements were generally done in closed systems, such as sealed, evacuated silica tubes. We measured the sulfur vapor pressure over pyrite in an open system where carrier gas is flowing through a gas mixing furnace, from 441 to 591°C in He, N 2, CO 2, and CO 2SO 2CO mixtures using a standard technique, the transpiration method (Merton, U. and Bell, W. E. (1967) The transpiration method. In The Characterization of High Temperature Vapors, ed. J. W. Margrave, pp. 91–114. Wiley, New York). The data show that the sulfur vapor pressure over pyrite is the same in inert gas and in CO 2-bearing gases. Our data also agree with literature vapor pressure data. Thermodynamic calculations show that the laboratory vapor pressure data are also valid at Venus surface pressures (≈ 50–100 bar). Finally, we present recommended values for the sulfur vapor pressure and calculate the molecular speciation of sulfur vapor over pyrite at Venus surface temperatures.

The solubility and oxidation state of nickel in silicate melt at low oxygen fugacities: Results using a mechanically assisted equilibration technique

The solubility of Ni in a silicate melt has been measured using a new, mechanically assisted equilibration technique over a wide range of controlled ƒ O 2 values. The melt composition corresponds to the 1 atm eutectic in the system CaAl 2Si 2O 8-CaMgSi 2O 6 + 10 wt% CaO. The experiments were performed at 1300°C and over an ƒ O 2 range of 10 −8.5 to 10 −13.75, and over a temperature range of 1270 to 1390°C at a constant gas mixing ratio ( CO 2 CO = 1:1 ). The experiment consists of a sample of melt contained within a crucible of Ni metal and held in a 1 atm gas mixing furnace. A Ni spindle is entered into the sample from above and continuously rotated at a constant angular velocity using a viscometer head. The stirring of the sample serves to accelerate the approach to equilibrium between the liquid sample and the metal crucible (and spindle). This arrangement allows relatively rapid equilibration of Ni content following changes to higher or lower ƒ O 2 values. Samples of the melt may be taken at any time for analysis and thus the equilibrium solubility of Ni in the silicate melt may be determined from unambiguous experimental reversals. The Ni contents of samples, analysed both by INAA and by ICP-AES, range from 25 to 5300 ppm. The data presented in this paper indicate that the oxidation state of Ni in the investigated melt is Ni 2+ over the entire range of ƒ O 2 investigated. This conclusion contrasts with recent reports in the literature of an inflection in the ƒ O 2 dependence of Ni solubility, which has been interpreted as solution of neutral Ni at low ƒ O 2 ( Morse et al., 1991; Colson, 1992; Ehlers et al., 1992). We also present data for the temperature dependence of Ni solubility in the investigated melt. The solubility decreases with increasing temperature at constant ƒ O 2 . The present results are in good agreement with the metal-loop-equilibration experiments reported by Holzheid et al. (1994).

Redox viscometry of some Fe-bearing silicate melts

The dependence of shear viscosity on the oxidation state of six ferrosilicate melts has been measured using the concentric cylinder method and a gas mixing furnace. The measurements were performed under air, COr, and COr-CO mixtures at I atm and in a temperature range of 1345 to 1470C. The experimental procedure involved a continuous measurement of viscosity during stepwise reduction of the melts. Melt chemistry was controlled by dip sampling the tiquids at each oxidation state. The resulting glassesw ere analyzed by electron microprobe, a volumetric FeO itration, and 57Fe Mdssbauer spectroscopy. The electron microprobe data indicate Fe loss for some of the most reduced samples.T he wet chemical (+ microprobe) and spectroscopicd eterminations of theseF erich samples yield oxidation states that are in excellent agreement. The viscosity of all melts investigated herein decreasesw ith melt reduction. The viscosity decrease is, in general, a nonlinear function of oxidation state expressed as Fe2*/F€,o,.

The system Fe-Si-O: Oxygen buffer calibrations to 1,500K

The five solid-phase oxygen buffers of the system Fe-Si-O, iron-wuestite (IW), wuestite-magnetite (WM), magnetite-hematite (MH), quartz-iron-fayalite (QIF) and fayalite-magnetite-quartz (FMQ) have been recalibrated at 1 atm pressure and temperatures from 800°–1,300° C, using a thermogravimetric gas mixing furnace. The oxygen fugacity, $$f_{{\text{O}}_{\text{2}} }$$ was measured with a CaO-doped ZrO2 electrode. Measurements were made also for wuestite solid solutions in order to determine the redox behavior of wuestites with O/Fe ratios varying from 1.05 to 1.17. For FMQ, additional determinations were carried out at 1 kb over a temperature range of 600° to 800° C, using a modified Shaw membrane. Results agree reasonably well with published data and extrapolations. The reaction parameters K, ΔG r o , ΔH r o , and ΔS r o were calculated from the following log $$f_{{\text{O}}_{\text{2}} }$$ /T relations (T in K): $$\begin{gathered} {\text{IW }}\log f_{{\text{O}}_{\text{2}} } = - 26,834.7/T + 6.471\left( { \pm 0.058} \right) \hfill \\ {\text{ }}\left( {{\text{800}} - 1,260{\text{ C}}} \right), \hfill \\ {\text{WM }}\log f_{{\text{O}}_{\text{2}} } = - 36,951.3/T + 16.092\left( { \pm 0.045} \right) \hfill \\ {\text{ }}\left( {{\text{1,000}} - 1,300{\text{ C}}} \right), \hfill \\ {\text{MH }}\log f_{{\text{O}}_{\text{2}} } = - 23,847.6/T + 13.480\left( { \pm 0.055} \right) \hfill \\ {\text{ }}\left( {{\text{1,040}} - 1,270{\text{ C}}} \right), \hfill \\ {\text{QIF }}\log f_{{\text{O}}_{\text{2}} } = - 27,517.5/T + 6.396\left( { \pm 0.049} \right) \hfill \\ {\text{ }}\left( {{\text{960}} - 1,140{\text{ C}}} \right), \hfill \\ {\text{FMQ }}\log f_{{\text{O}}_{\text{2}} } = - 24,441.9/T + 8.290\left( { \pm 0.167} \right) \hfill \\ {\text{ }}\left( {{\text{600}} - 1,140{\text{ C}}} \right). \hfill \\ \end{gathered}$$ These experimentally determined reaction parameters were combined with published 298 K data to determine the parameters Gf, Hf, and Sf for the phases wuestite, magnetite, hematite, and fayalite from 298 K to the temperatures of the experiments. The T− $$f_{{\text{O}}_{\text{2}} }$$ data for wuestite solid solutions were used to obtain activities, excess free energies and Margules mixing parameters. The new data provide a more reliable, consistent and complete reference set for the interpretation of redox reactions at elevated temperatures in experiments and field settings encompassing the crust, mantle and core as well as extraterrestrial environments.