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Thermodynamics Interaction Studies Solids, Liquids and Gases Part 15

Tham khảo tài liệu 'thermodynamics interaction studies solids, liquids and gases part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 830 Thermodynamics rinteraction st udies fSolids Liquids and Gases When CaO is insufficient redundant AI2O3 may promote the newly generated high calcium-to-aluminum ratio CaO to AI2O3 mole ratio calcium aluminates to transform into lower calcium-to-aluminum ratio calcium aluminates. The reactions of the equations are presented in table 5 The relationships between G of reactions of AbOs-calcium aluminates system and temperature T are shown in figure 6. 200 400 600 800 1000 1200 1400 1600 1800 T K Fig. 6. Relationships between G of reactions AbOs-calcium aluminates system and temperature Figure 6 shows that Gibbs free energy of the reaction of AbOs-calcium aluminates system are negative at 400-1700K and all the reactions automatically proceed to generate the corresponding low calcium-to-aluminum ratio calcium aluminates Except for the reaction of AI2O3-C12A7 the G of the rest reactions decreases with the rise of temperature and becomes more negative. Comparing figure 4 with figure 5 it can be found that AI2O3 reacts with CaO easily to generate C12A7. 2.6 SiO2- CaO system S1O2 can react with CaO to form CaO S1O2 CS 3CaO 2SiC 2 C3S2 2CaO -SiC 2 C2S and 3CaO SiOsfC S in roasting process. The reactions are shown in table 6 and the relationships between AG of the reactions of S1O2 with CaO and temperature are shown in figure 7. Reactions A J mol B J Kmol Temperature K CaO SiC 2 CaO SiChipseud-wollastonite -83453.0 -3.4 298-1817 CaO SiC 2 CaO SiC 2 wollastonite -89822.9 -0.3 298-1817 ịcaO SiO ị 3CaO 2SiO -108146.6 -3.1 298-1700 3CaO SiC 2 3CaO SÌO2 -111011.9 -11.3 298-1800 2CaO SiC 2 - 2CaO SiO2 P -125875.1 -6.7 298-2403 2CaO SiC 2 2CaO SiChW -137890.1 3.7 298-1100 Table 6. The G of SiC 2-CaO system G A BT J mol Thermodynamics of Reactions Among AI2O3 CaO SiO2 and Fe2O3 During Roasting Processes 831 -70 -80 -90 s -100 o s -110 S e- -120 13 -140 -150__ 200 400 600 800 1000 1200 1400 1600 T K Fig. 7. Relationships between G and temperature Figure shows that S1O2 reacts with