A fast-quench device for internally heated pressure vessels

Roux, Jacques; Lefèvre, André

doi:10.1127/ejm/4/2/0279

Cited by 45 publications

(18 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Effect of sulfur on gold solubility in arc magmas furnace was used, allowing the 4-6 cm hot spot zone to be focused at the level of the sample holder, with a thermal gradient less than 2°C across (Roux and Lefèvre, 1992). Temperature was measured by two sheathed chromel-alumel thermocouples, calibrated at 1 atm against the melting point of NaCl (800.5°C), and is considered known to within ±5°C.…”

Section: Line Missingmentioning

confidence: 99%

Gold solubility in arc magmas: Experimental determination of the effect of sulfur at 1000 °C and 0.4 GPa

Jégo

Pichavant

2012

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

To investigate the behaviour of gold in sulfur-bearing hydrous intermediate calc-alkaline melts under different redox states typical of subduction-zone settings, we have determined the solubility of Au at 0.4 GPa and 1000°C for three dacitic magmas (two adakites and one calc-alkaline composition) from the North-Luzon Arc (Philippines). The experiments were performed over an oxygen fugacity (fO 2 ) range corresponding to reducing ($NNOÀ1), moderately oxidizing ($NNO+1.5) and strongly oxidizing (PNNO+3) conditions as measured by solid Ni-Pd-O sensors. They were carried out in gold containers, serving also as the source of gold, in presence of variable amounts of H 2 O and $1 wt.% of elemental sulfur (S). Concentrations of Au in glasses were determined by laser-ablation inductively-coupled plasma mass spectrometry (LA-ICPMS). Gold solubility in S-bearing melts is drastically enhanced compared to S-free melts, by up to two orders of magnitude. In addition, very high gold solubilities are reached under reducing conditions (

show abstract

Section: Line Missingmentioning

confidence: 99%

Gold solubility in arc magmas: Experimental determination of the effect of sulfur at 1000 °C and 0.4 GPa

Jégo

Pichavant

2012

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

show abstract

“…The fH 2 values mentioned in Table 2 and Table 3 correspond to experimental hydrogen pressures calculated from the fO 2 of the final products. The experiments were rapidly-quenched by electrically melting the Pt wire that suspended the sample holder in the vessel hot spot zone ( [Roux and Lefèvre, 1992] and [Di Carlo et al, 2006]). This caused the sample holder to drop to the cold end of the vessel with quench rates of the order of 300 °C/s.…”

Section: Experimental Equipment and Proceduresmentioning

confidence: 99%

Controls on gold solubility in arc magmas: An experimental study at 1000°C and 4kbar

Jégo

Pichavant

Mavrogenes

2010

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

In order to (1) explain the worldwide association between epithermal gold-coppermolybdenum deposits and arc magmas and (2) test the hypothesis that adakitic magmas would be Au-specialized, we have determined the solubility of Au at 4 kbar and 1000 °C for three intermediate magmas (two adakites and one calc-alkaline composition) from the Philippines. The experiments were performed over a fO 2 range corresponding to reducing ( NNO−1), moderately oxidizing ( NNO+1.5) and strongly oxidizing ( NNO+3) conditions as measured by solid Ni-Pd-O sensors. They were carried out in gold containers, the latter serving also as the source of gold, in presence of variable amounts of H 2 O and, in a few additional experiments, of S. Concentrations of Au in glasses were determined by LA-ICPMS. Gold solubility in melt is very low (30-240 ppb) but increases with fO 2 in a way consistent with the dissolution of gold as both Au 1+ and Au 3+ species. In the S-bearing experiments performed at NNO−1, gold solubility reaches much higher values, from 1200 to 4300 ppb, and seems to correlate with melt S content. No systematic difference in gold solubility is observed between the adakitic and the non-adakitic compositions investigated. Oxygen fugacity and the sulfur concentration in melt are the main parameters controlling the incorporation and concentration of gold in magmas. Certain adakitic and non-adakitic magmas have high fO 2 and magmatic S concentrations favorable to the incorporation and transport of gold. Therefore, the cause of a particular association between some arc magmas and Au-Cu-Mo deposits needs to be searched in the origin of those specialized magmas by involvement of Au-and S-rich protoliths. The subducted slab, which contains metal-rich massive sulfides, may constitute a potentially favorable protolith for the genesis of magmas specialized with respect to gold.

show abstract

“…At the end of the experiment the electrodes were connected to a variac and the voltage was increased which led to electrical fusion of the quench wire and the sample holder dropped into the cold bottom part (T < 50°C) of the vessel. The cooling time to room temperature for a quenched sample is estimated to be less than 1 min [33] with high quench rates of 100-50°C/s at the beginning and decreasing quench rates near the end of the cooling. During the experiment, the suspended sample holder was located in the hot spot zone of the furnace, where the thermal gradient could be minimized to less than 5°C by adjusting the power supplies of two windings.…”

Section: Apparatus and Experimental Conditionsmentioning

confidence: 99%

“…The experiments were performed in an internally heated pressure vessel (IHPV), equipped with the fast-quench device of Roux and Lefèvre [33] which was modified for this study. In contrast to the original setup the sample capsules were placed in a sample holder (alumina tube 50 mm in length, 10 mm inner diameter and 0.6 mm wall thickness); the free volume of this tube was filled with silica wool.…”

Section: Apparatus and Experimental Conditionsmentioning

confidence: 99%

Incorporation of H2 in vitreous silica, qualitative and quantitative determination from Raman and infrared spectroscopy

Schmidt

Holtz

Bény

1998

Journal of Non-Crystalline Solids

View full text Add to dashboard Cite

Incorporation mechanisms of H 2 in silica glass were studied with Raman and infrared (IR) microspectroscopy. Hydrogenated samples were prepared at temperatures between 800°C and 955°C at 2 kbar total pressure. Hydrogen fugacities (f H2 ) were controlled using the double capsule technique with the iron-wüstite (IW) buffer assemblage generating f H2 of 1290-1370 bars corresponding to H 2 partial pressures (P H2 ) of 960-975 bars. We found that silica glass hydrogenated under such conditions contains molecular hydrogen (H 2 ) in addition to SiH and SiOH groups. H 2 molecules dissolved in the quenched glasses introduce a band at 4136 cmin the Raman spectra which in comparison to that of gaseous H 2 is wider and is shifted to lower frequency. IR spectra of hydrogenated samples contain a band at 4138 cm −1 which we assign to the stretching vibration of H 2 molecules located in non-centrosymmetric sites. The Raman and IR spectra indicate that the dissolved H 2 molecules interact with the silicate network. We suggest that the H 2 band is the envelope of at least three components due to the occupation of at least three different interstitial sites by H 2 molecules. Both, Raman and IR spectra of hydrogenated glasses contain bands at 2255 cm −1 which may be due to the vibration of SiH groups. Under the assumption that the reaction Si-O-Si + H 2 → Si-H + Si-O-H describes adequately the 'chemical dissolution' of H 2 molecules, the SiH concentrations in our samples were determined and the molar extinction coefficient for the SiH absorption band in the infrared ( 2255 (SiH)) could then be estimated to be 45 ± 3 l/mol cm. The solubility of molecular H 2 in our hydrogenated samples was determined using the IR absorption band at 4138 cm −1 and the extinction coefficient given by Shelby [J. Non-Cryst. Solids 179 (1994) 138]. Samples quenched with different cooling rates gave nearly identical Raman and IR spectra, suggesting that the chemical dissolution of hydrogen (SiH and SiOH) can be quenched to room temperature without changing relative concentrations and that no exsolution of hydrogen occurred during the quench.

show abstract

A fast-quench device for internally heated pressure vessels

Cited by 45 publications

References 0 publications

Gold solubility in arc magmas: Experimental determination of the effect of sulfur at 1000 °C and 0.4 GPa

Gold solubility in arc magmas: Experimental determination of the effect of sulfur at 1000 °C and 0.4 GPa

Controls on gold solubility in arc magmas: An experimental study at 1000°C and 4kbar

Incorporation of H2 in vitreous silica, qualitative and quantitative determination from Raman and infrared spectroscopy

Contact Info

Product

Resources

About