Physical Chemistry Of Process Metallurgy

Richardson, F. D.

doi:10.1038/162719a0

Cited by 75 publications

(47 citation statements)

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“…The molecular oxygen solubility has rarely been measured in silica-free melts in the range of temperature foreseen for MOE, and the value reported [16] for PbO-SiO 2 melts at 1250°C is below 100 mol.m -3 . The order of magnitude of the molecular oxygen diffusivity in CaO-SiO 2 -Al 2 O 3 at 1450°C has been measured at 10 -9 m 2 .s -1 [17]. Both molecular oxygen concentration and diffusivity are predicted to increase as the optical basicity (i.e.…”

Section: Molecular Oxygen In Oxide Meltsmentioning

confidence: 99%

Electrochemical engineering of anodic oxygen evolution in molten oxides

Allanore

2013

Electrochimica Acta

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Molten oxide electrolysis (MOE) is a metal extraction process that exhibits an exceptionally high productivity in comparison with other electrowinning techniques.Furthermore, MOE has the ability to generate oxygen as an environmentally benign byproduct, which is a key asset to improve metal extraction sustainability. From an electrochemical engineering standpoint, the high concentration of metal cations dissolved in the electrolyte justifies cathode current densities above 10 000 A.m -2 . At the anode, the available data suggest a mechanism of oxidation of the free oxide anions which concentration in oxide melts is reported to be limited. In this context, the application of available mass-transfer correlations for the anodic oxygen evolution suggests a key role of convection induced by gas bubbles evolution.

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Section: Molecular Oxygen In Oxide Meltsmentioning

confidence: 99%

Electrochemical engineering of anodic oxygen evolution in molten oxides

Allanore

2013

Electrochimica Acta

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“…The rate of the evaporation of a substance at elevated temperatures can be calculated by the Hertz-LangmuirKnudsen equation [21]. When a perfect vacuum is not used, i.e.…”

Section: Phosphorus Evaporationmentioning

confidence: 99%

Kinetics and Mechanism of Phosphorus Removal from Silicon in Vacuum Induction Refining

Safarian

Tangstad

2012

High Temperature Materials and Processes

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Abstract. Vacuum induction refining is a process that can be applied to remove phosphorus from molten silicon for the production of solar grade silicon. Pure silicon was doped by phosphorus to make molten silicon containing around 17 ppmw phosphorus. The kinetics of phosphorus removal from this silicon was studied at 0.5 Pa through the application of vacuum induction refining. It was observed that vacuum removal of phosphorus occurs through a first-order reaction. The rate constants of phosphorus evaporation were determined as 2.28 10 6 m=s and 4.93 10 6 m=s at 1500 ı C and 1600 ı C, respectively. Moreover, an apparent activation energy 213.1 kJ=mol for phosphorus evaporation from molten silicon was calculated. It was found that mass transfer of phosphorus in the melt is not rate limiting in the inductively stirred silicon melt. The vacuum removal of phosphorus is mix-controlled by chemical reaction and gas phase mass transfer. Under medium vacuum conditions, the mass transfer in the gas phase is more rate-limiting than the chemical reaction at higher refining temperatures.

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“…The latter view is based on their similar vaporization enthalpies (i.e., the slopes of their vapor pressure curves; compare 0 H° /z between (13) and (18) or between (14) and (19) in Table 6), and on the weak temperature dependences of activity coefficients in most binary silicate melts (RICHARDSON, 1974). An additional support of this view is obtained from the experimental result that the volatility ratio of MgO to Si02 varies only little with temperature as indicated in Fig.…”

Section: The Reportedmentioning

confidence: 99%

“…b: ibid. (excess entropy of configuration only is put at zero; the empirical relation is used between excess ther mal entropy and excess thermal enthalpy, ASt " ' l 3,000 (RICHARDSON, 1974)). Arguments in the text are based on a, but do not differ qualitatively on b. Roman numerals, I and II, denote the evaporation stages.…”

Section: Stage IIImentioning

confidence: 99%