The Effect of Fe~(3+)/Fe~(2+) ratio on the Anionic structure of Iron-Bearing Silicate Melts

摘要

The effects of the coordination of iron ions on the anionic structure of molten iron oxide bearing sodium silicate slags at 1273K and calcium silicate at 1873K have been investigated by using Raman spectroscopy. The Raman spectra of Na_2O*2SiO_2-FeO-Fe_2O_3 and CaO*1.5SiO_2-FeO-Fe_2O_3 systems with various pO_2 is measured. Under low pO_2 condition (CO_2/CO < 10), the Raman spectra of Na_2O*SiO_2-FeO- Fe_2O_3 are essentially the same to that of Na_2O*SiO_2 and Fe~(2+) is supposed to work as network modifier. However, under high pO_2 condition (CO_2/CO >54), new Raman band of 900 cm~(-1) appears and its intensity increases with the increase of pO_2 and iron oxide content. This 900 cm~(-1) band can be resulted from the network structure of Fe~(3+). It is confirmed that Fe~(3+) ion in Na_2O*2SiO_2-FeO-Fe_2O_3 system works as a network former and Fe~(2+) as a network modifier. In the CaO*1.5SiO_2-FeO-Fe_2O_3 systems, with increase of pO_2 and Fe_2O_3 content, individual bands of 1100, 950 and 850 cm~(-1) observed in CaO*1.5SiO_2 have merged together and forms an envelope in the high frequency region. By deconvolution of this envelope, 900cm~(-1) band is unresolved. The intensity of low frequency region progressively increases with pO_2 and Fe_2O_3 content. Based on these results, Fe~(3+) is confirmed to work as a network former. Under low pO_2 condition (CO_2/CO=1.5), the Raman spectra of CaO*1.5SiO_2-FeO- Fe_2O_3 are essentially the same to that of CaO*1.5SiO_2 and Fe~(2+) was concluded to work as a network modifier.