Electric transport in liquid silicates

Bockris, J. O'm.; Kitchener, J. A.; Davies, A.E.

doi:10.1039/tf9524800536

Cited by 65 publications

(21 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(10)) as likely as viscosity does. [20][21][22] . The activation energy for electric conduction (Eκ) decreases with increasing content of network-modifying oxides.…”

Section: Electrical Conductivitymentioning

confidence: 99%

“…They also made the important observation that the activation energy is from 2 to 5 times smaller for electrical conduction than for viscous flow, indicating that the two properties are governed by different mechanisms with different energy barriers. 21) Vibrational spectroscopy, specifically Raman spectroscopy was originally used to probe the local anionic structure of silicates. 22,23) The bands assigned to antisymmetric stretching of Si-O -(non-bridging oxygen; NBO) and Si-O 0 (bridging oxygen; BO) bonds occur in the 850-1 200 cm -1 region, whereas Si-O-Si bending modes are found between about 500 and 700 cm -1 .…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, many scientists have tried to measure and/or predict these macroscopic thermophysical properties as a function of composition of silicates based on the microscopic view of structures. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Viscosity (η ) is of particular importance because it controls the rate of transport of matter and thus, of energy. 1,2,22) Generally, the largest changes in the viscosity of silicate melts are found when metal oxides, MO (M = alkali, alkaline earth, etc.)…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Structure^|^ndash;Property Correlations of CaO^|^ndash;SiO2^|^ndash;MnO Slag Derived from Raman Spectroscopy

Park

2012

ISIJ Int.

109

View full text Add to dashboard Cite

The quantitative structural information such as the relative abundance of silicate discrete anions (Q n units) and the concentration of three types of oxygens, viz. free-, bridging-and nonbridging oxygen can be obtained from micro-Raman spectra of the quenched CaO-SiO2-MnO glass samples. Various transport properties such as viscosity, density, and electrical conductivity can be expected as a simple linear function of 'ln (Q 3 /Q 2 ),' indicating that these thermophysical properties are strongly dependent on a degree of polymerization of silicate melts in the composition of silica content greater than about 30 mol%. The present methodology is believed to be widely extended to various slag systems in ferrous and non-ferrous metallurgical communities.KEY WORDS: silicate structure; Raman spectroscopy; viscosity; density; conductivity; Q 3 /Q 2 ratio; degree of polymerization.

show abstract

“…(10)) as likely as viscosity does. [20][21][22] . The activation energy for electric conduction (Eκ) decreases with increasing content of network-modifying oxides.…”

Section: Electrical Conductivitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Structure^|^ndash;Property Correlations of CaO^|^ndash;SiO2^|^ndash;MnO Slag Derived from Raman Spectroscopy

Park

2012

ISIJ Int.

109

View full text Add to dashboard Cite

show abstract

“…Bockris et al 1 carried out pioneering research on the anion species in silicate melts and postulated that discharge of free oxygen ions is related to the concentration of free oxygen ions in silicate melts and the structural equilibrium of the silicate units. Moreover, basicity, which is most appropriate to be defined by the activity of a free oxygen ion, could be used to monitor free oxygen ions and understand the equilibrium state of silicate melts.…”

mentioning

confidence: 99%

Influence of Basicity on Anodic Reaction in CaO-SiO₂-Al₂O₃Melts

Lee

Min

2017

J. Electrochem. Soc.

View full text Add to dashboard Cite

A cyclic voltammetry study on the anodic reaction between carbon electrodes and CaO-SiO 2 -Al 2 O 3 melts at 1773 K was carried out to understand the electrochemical behavior of free oxygen ions in silicate melts. The potential of free oxygen ions corresponding to CO evolution in the totally diffusion controlled region was obtained from the voltammetric data. An empirical relationship between the current density on the logarithm scale and the basicity (B) of each silicate melt was established through Tafel analysis in the non-diffusion-controlled region. The obtained electrochemical data showed good correlation with thermodynamic properties such optical basicity and sulfide capacity of the silicate melts as a relative index of oxygen ion activity in molten oxides. The use of this electrochemical method to evaluate the relative potential of oxygen ions in molten oxides is discussed in detail. Bockris et al.1 carried out pioneering research on the anion species in silicate melts and postulated that discharge of free oxygen ions is related to the concentration of free oxygen ions in silicate melts and the structural equilibrium of the silicate units. Moreover, basicity, which is most appropriate to be defined by the activity of a free oxygen ion, could be used to monitor free oxygen ions and understand the equilibrium state of silicate melts. Electrochemical research on the anodic reaction of free oxygen ions has been continuously pursued to determine the potential of molten oxides as electrolytes in various electrochemical applications, namely, molten oxide electrolysis (MOE), 2-12 direct current electro-slag remelting (DC-ESR), 13 and electrorefining. [14][15][16][17] Since basicity as a measure of oxygen ions in molten oxides is a fundamental index for defining the equilibrium state of chemical reactions in molten oxides, extensive research has been carried out using basicity measurements to define the chemical potential of oxygen ions in molten oxides qualitatively. However, it is difficult to directly evaluate the activity of free oxygen ions because it is impossible to experimentally measure the chemical potential of ionic species in solution due to the constrain of electro-neutrality.18 Therefore, many studies have used indirect methods to quantify free oxygen ions in molten oxides. Wagner 19 proposed an indirect basicity concept using sulfide capacity as a quantitative index. A linear correlation between sulfide capacity and basicity is observed in a certain composition range. However, it is assumed that the activity coefficient of the reaction product is independent from the composition, which is the standard state defined by Henry's law. Therefore, for various oxide systems with wide ranges of basicity, the capacity only allows a qualitative comparison owing to change in the activity coefficient of the product. Therefore, Nakamura and Sano 20 measured the solubility of platinum in CaO-SiO 2 and BaO-SiO 2 systems and in CaO-Al 2 O 3 and BaO-Al 2 O 3 systems, while Park and Min 21 measured the solubility of...

show abstract

“…The cation contribution increases with the basicity and concentration of the network modifiers, as illustrated in Figure 7. Silicate binaries exhibit electrical conduction that is thermally activated with an activation energy barrier nearly half that for viscous flow (between 10 and 20 kcal · mol −1 ), 33,34 though the correlation is not valid for all oxides at any composition. Data for non-silicate molten oxides are scarcer.…”

Section: A Supporting Electrolyte and Two Electrodesmentioning

confidence: 99%

Features and Challenges of Molten Oxide Electrolytes for Metal Extraction

Allanore

2014

J. Electrochem. Soc.

View full text Add to dashboard Cite

The electrolytic decomposition of metal oxides to metal and oxygen is an extractive metallurgy principle that, when coupled with carbon-free electricity, drastically mitigates the global warming impact of metal production. The present perspective discusses the electrochemical engineering features of an unconventional electrolyte, molten oxides. A survey of its thermodynamic properties suggests exceptional features, both in terms of applicability to multiple metals and operation at high temperature to produce liquid metal. The review of molten oxides' transport properties indicates that an unprecedented throughput can be envisioned, a promising feature for tonnage production. However, our ability to define the optimal electrolyte composition with regard to energy consumption is rendered limited due to the lack of predictive tools for both of the reviewed properties. A look at the state of the art in electrode materials reveals that quantitative design criteria remain to be developed for both the cathode and the anode. Metals have been essential materials for mankind for more than 2 millennia, and they remain the most important materials in terms of market value. Because of their centrality in the structural framework of the modern world, some metals have developed a commodity status, much like water or food. In the last two decades, an unprecedented increase in the global demand for metals has occurred ( Figure 1a). This trend is expected to continue with the world population predicted to reach 9 billion by 2020.Such growth does not come without challenges, particularly when it comes to the sustainability of primary metal production. Current extraction and processing routes are indeed characterized by large capital and environmental impacts. The former issue leads to difficulty in financing new facilities, particularly in developing countries that are poised to become significant consumers of primary metals. The existing technical paradigm necessitates multi-billion dollar investments that in turn require exceptional profits and short-term metal price stability in order to be supported by financing organizations. The environmental impact, illustrated in Figure 1b via the specific global warming and acidification potentials of key metals, can hinder the implementation of greenfield plants in countries with the most stringent environmental regulations. Additionally these emission potentials constitute a threat to the market in the eventuality of their taxation.The present perspective offers first to reconsider the existing paradigm for the extraction of metals from oxides, which accounts for the majority of metal resources in tonnage and value. In particular, this document focuses on the use of electricity for the direct decomposition of metal oxides. The first section discusses the metallurgical strategies to extract a metal (M) from its oxide (MO) and the characteristics of the direct electrolytic decomposition pathway. In the second section, an argument is made for the use of molten oxides as a possible supporti...

show abstract

Electric transport in liquid silicates

Cited by 65 publications

References 2 publications

Structure^|^ndash;Property Correlations of CaO^|^ndash;SiO2^|^ndash;MnO Slag Derived from Raman Spectroscopy

Structure^|^ndash;Property Correlations of CaO^|^ndash;SiO2^|^ndash;MnO Slag Derived from Raman Spectroscopy

Influence of Basicity on Anodic Reaction in CaO-SiO₂-Al₂O₃Melts

Features and Challenges of Molten Oxide Electrolytes for Metal Extraction

Contact Info

Product

Resources

About

Electric transport in liquid silicates

Cited by 65 publications

References 2 publications

Structure^|^ndash;Property Correlations of CaO^|^ndash;SiO2^|^ndash;MnO Slag Derived from Raman Spectroscopy

Structure^|^ndash;Property Correlations of CaO^|^ndash;SiO2^|^ndash;MnO Slag Derived from Raman Spectroscopy

Influence of Basicity on Anodic Reaction in CaO-SiO2-Al2O3Melts

Features and Challenges of Molten Oxide Electrolytes for Metal Extraction

Contact Info

Product

Resources

About

Influence of Basicity on Anodic Reaction in CaO-SiO₂-Al₂O₃Melts