WANG Haonan, XUAN Weiwei, XIA Dehong. Structural evolution of coal ash slag at different temperatures[J]. CIESC Journal, 2019, 70(8): 3094-3103DOI: 10.11949/0438-1157.20190310.
Structural evolution of coal ash slag at different temperatures
The structural characteristics of high iron coal ash melt and the variation of structure with temperature were studied by thermodynamic calculation and molecular dynamics simulation. The contents of Fe
3+
and Fe
2+
at different temperatures were calculated
and the radial distribution function
coordination number
bond angle
coordination state of oxygen and Q
n
structural units were analyzed. The results of thermodynamic calculations show that the increase of temperature is beneficial to the conversion of Fe
3+
to Fe
2+
and the change of Fe
3+
/Fe
2+
with temperature is obtained. Based on the BMH potential function
molecular dynamics simulations show that the melt has short-range order and long-range disordered structural features. As the temperature increases
the height and sharpness of the radial distribution function curve of each ion pair decrease
the higher coordination state of each ion decreases and the lower coordination state increases
the height and sharpness of the bond angle curve decrease and the first peak moves in a smaller direction. These phenomena all indicate that the
degree of aggregation of ions is weakened
and the degree of disorder inside the melt is enhanced. The coordination state of oxygen and the change of Q
n
are a direct reflection of the change of melt polymerization degree. The increase of temperature leads to the decrease of tri-coordinate oxygen and bridge oxygen
and the increase of non-bridge oxygen and free oxygen. Q
4
structural unit disintegrated to generate Q
3
Q
2
Q
1
and Q
0
structural units with lower degree of polymerization.
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