Crystallization phenomena in iron-rich glasses

Effect of particle size on kinetics crystallization of an iron-rich glass

“…As to finer fractions with particle size <100µm, n and m parameters are shifted to values close to 2, which indicates an interface reaction mechanism with two-dimensional growth of pyroxene crystals with plates-like morphology. The values of n for f1-f6 fractions are in the 1.40-1.65 interval, which is in agreement with values of n in the 1.2-1.8 interval previously reported on iron-rich glasses [16,21,32]. As for m parameter, there is a lack in the literature on the determination of such parameter and hence, it was not possible to evaluate against similar glasses.…”

“…The exothermic peak is due to the crystallization of a pyroxene phase from the diopside-hedenbergite group, which forms a completed solidsolution series between CaMgSi 2 O 6 (diopside) and CaFeSi 2 O 6 (hedenbergite) [30], as has been identified by XRD analysis on NLR glass sintered at 750ºC during 30 min (Figure 1). Pyroxene-type phases are typical phases precipitated in glass-ceramics from iron-rich wastes, in which crystallization occurs through liquid-liquid immiscibility, where one of the liquid phases is richer in iron and promotes a spontaneous formation of the magnetite spinels nano-crystals, which act as nuclei for the formation of the main pyroxene phase [31,32]. Figure 3 depicts the DTA curves recorded on different particle size fractions of NLR glass at a heating rate of 25ºC.…”

Final Report - Effects of High Spinel and Chromium Oxide Crystal Contents on Simulated HLW Vitrification in DM100 Melter Tests, VSL-09R1520-1, Rev. 0, dated 6/22/09

“…Skeletons of dissolving spinel crystals were observed in samples from the melt (Figure 4.13b). Decomposition by oxidation of iron-rich spinel into hematite is a known phenomenon [53,54]. The abundance of hematite (up to 95% of all crystals in the melt with only 5% spinel (Figure 4.30, Test 2, Samples 1, 5, 6, and 7); see also Figure 4.16b), suggests that there may be continuous formation of iron-rich spinel containing Fe 2+ and subsequent decomposition of this spinel by oxidation.…”

Crystallization Properties of the Glass Ceramics Prepared from Iron-Rich Nickel Slag

“…The study on preparing the glass ceramics with the industrial wastes has been made since 1960s, and some results were widely reported [1]. And several systems can be used to prepare the glass ceramics, for example, the system of SiO 2 -Al 2 O 3 -CaO-MgO, SiO 2 -Al 2 O 3 -CaO-Fe 2 O 3 , and SiO 2 -Al 2 O 3 -CaO-Na 2 O [2][3][4][5]. In this research, how to prepare glass ceramics with high content iron-rich nickel slag (more than 90%) was discussed.…”