The reduction process of artificial 2CaO·Fe
2O
3, CaO·Fe
2O
3 and CaO·2Fe
2O
3 by CO-CO
2 mixed gas and the accompanied expansion have been studied in connection with the behaviour during reduction of lime self-fluxing sinter. The main results obtained are as follows :
(1) A scheme of reduction process of CaO·2Fe
2O
3, CaO·Fe
2O
3 and 2CaO·Fe
2O
3 at 800°, 900°, 1 000 °C (solid line) and 550°C (chain line) was found as follows :
(2) At 800°, 900°, and 1 000°C, the expansion (about 0.8%) in the reduction of CaO·2Fe
2O
3 and CaO·Fe
2O
3 occurred up to formation of 2CaO·Fe
2O
3, Ca0·3FeO.Fe
2O
3 and Fe
xO, and the expansion in the case of 2CaO·Fe
2O
3 was only small.
(3) At 550°C, the abrupt expansion (about 4%) in the reduction of CaO·Fe
2O
3 may be caused by formation of metallic iron and carbon deposition incidental to its formation, and that the expansion in the reduction of CaO·2Fe
2O
3 occurred in two steps; the first step expansion (about 0.8%) occurred up to formation of Fe
3O
4 and the second abrupt expansion may be caused by the same reason as in CaO·Fe
2O
3.
(4) At each temperature, the expansion of Fe
2O
3 was the highest and the expansion of calcium ferrite was much less than Fe
2O
3, and the expansion of binary calcium ferrite increased with increasing Fe
2O
3 content in ferrite.
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