17.反应罐生产海绵铁的影响因素探究*

 陶凯，赵增武

( 内蒙古科技大学材料与冶金学院，内蒙古包头014010)

关键词: 半焦; 还原度; 金属化率; 晶须

中图分类号: TF553 文献标识码: A

摘要: 隧道窑是工业生产海绵铁的重要方法. 但生产过程温度低，产率不高. 按照某隧道窑尺寸，根据相似原理建立了实验室反应罐模型和装料制度. 用箱式电阻炉以6 ℃ /min 将物料从室温升至1 100 ℃，保温2 h 后快速水冷制得海绵铁样品. 实验发现: 10 ～ 16 目时还原度为69． 4%，金属化率也最高; 通过对10 ～ 16 目海绵铁样品沿径向取样进行SEM 观察，发现颗粒的微观结构差异很大; 分析表明微观结构主要影响径向传热和传质，从而导致海绵铁中间还原度最低; 内侧铁矿颗粒表面有晶须出现，其生长和发展导致颗粒体积膨胀; 外侧铁矿颗粒还原充分，大量失氧和晶须软熔渗透是导致海绵铁外径收缩和烧结的主要原因.

The research on the influenial factors over producing sponge iron in retort

TAO Kai，ZHAO Zeng-wu

( Material and Metallurgy School，Inner Mangolia University Of Science and Technology，Baotou 014010，China)

Key words: semi-coke; reduction degree; metallization degree; whisker

Abstract: Tunnel is an important method of making sponge iron industrially，but the yield is low because of low temperature and poor dynamics． According to the similar principle and a tunnel kiln size，the laboratory model of retort and the charging system were established．Materials are heated from room temperature to 1100 ℃ at the rate of 6 ℃ / min in a resistance furnace，with heat persevered for 2 hours，then cooled by running water． It was found that when the degree of reduction is 69． 4%，the rate of metallization is the highest;the SEM images of sponge iron samples along the radial direction indicate that the microstructures of the particles are very different．Analysis showed that the main effects of microstructures are on the radial heat and mass transfer，resulting in the lowest rate of reduction at intermediate of sponge iron; whiskers and growth of iron were observed，and the outside of iron ore particles was reduced thoroughly．A large loss of oxygen and whiskers melting and infiltration are the main reasons for the shrinkage and sintering at the outer diameter of sponge iron．