Effect of Wollastonite on Crystallization Properties of Mould Powder
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摘要: 以水泥熟料、工业矿物为主要原料,实验室配制保护渣,运用工艺矿物学方法,研究硅灰石对保护渣结晶性能及对应渣膜矿相结构的影响规律。结果表明:同一冷却速率下,随硅灰石含量的增加,试验渣的结晶温度逐渐降低;硅灰石每增加2%,临界冷却速度平均下降2℃/s;结晶孕育时间随硅灰石含量的增加而延长,利于铸坯的润滑。试验渣中硅灰石为11%~19%时,对应渣膜的结晶率均在80%以上,结晶矿物为枪晶石和硅灰石;原料中硅灰石11%~15%时,渣膜中两种结晶矿物的含量相当;硅灰石≥17%时,渣膜主要析出硅灰石,枪晶石含量明显减少,黏度增加幅度不大,但热流密度显著增大,不利于控制传热。为达到保护渣传热与润滑的统一,建议保护渣中硅灰石含量不大于15%。Abstract: The effect of wollastonite on crystallization properties and crystallization phase of mould powder made of cement clinker and industrial mineral raw materials in laboratory had been studied through process mineralogy. The results show that the crystallization temperature decreases with the content of wollastonite increasing at the same cooling speed. The critical cooling rate decreases by 2 ℃/s when increasing 2% wollastonite. And increasing wollastonite content leads to long incubation time of crystallization which can improve the lubrication degree of slab. When the content of wollastonite ranges from 11% to 19%,the crystallization ratio of the resulted mould flux is more than 80% where the main minerals in flux film are cuspidine and wollastonite. The contents of the two kinds of crystallization phase are similar when wollastonite is less than 15%. However,when the content of wollastonite is above 17%,the crystallization phase consists of more wollastonite and less cuspidine. At the same time,the viscosity increase somewhat but the heat flux increase obviously which is unbeneficial to control heat transfer. To achieve the balance of heat transfer and lubrication,the suggested content of wollastonite is 15% or less.
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Key words:
- continuous casting /
- mould powder /
- mineral compositon /
- wollastonite /
- flux film /
- crystallization properties
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