铁矿石直接还原提铁及制备胶凝材料的协同研究

发布时间：2018-05-21 00:14

  本文选题：赤铁矿 + 直接还原　； 参考：《西安建筑科技大学》2015年硕士论文

【摘要】：我国的铁矿石资源总储量充足,但矿石品位不高,贫杂铁矿较多,选矿难度大,常规炼铁工艺难以实现对其高效利用。随着富矿储量的日益减少,未来发展的趋势应该考虑如何实现贫铁矿石资源的高效生态化利用,即不仅利用其中的铁和有价金属资源,而且还应对其中脉石组分加以有效回用。为此探索一种技术可靠、经济合理的综合利用技术,对实现节能减排、减少污染的资源高效化利用具有重要的现实意义和应用价值。本文以赤铁矿为原料,以炭粉作为还原剂,进行了铁矿石直接还原提铁及制备胶凝材料协同研究。利用FACTSage软件对直接还原过程进行了相关相平衡计算,探讨了不同热力学条件下的铁矿石直接还原铁和胶凝材料协同反应的可能性。然后采用连续升温法和分阶段升温法进行直接还原实验,研究了反应温度、反应时间、还原剂配比、还原气氛、冷却方式对直接还原铁还原率和胶凝材料主要成分Ca3SiO5生成率的影响,并探讨了Ca3SiO5的生成机理。取得的研究成果如下:(1)对协同研究实验的热力学计算结果显示,在温度为1250℃~1450℃,碳量为理论量的0.75~1.0倍条件下,赤铁矿中Fe2O3直接还原铁的回收率随碳量的增加而增大;碳量大于理论碳量时,Fe的理论还原率可以达到99%以上。在温度低于1350℃时,理论上体系中没有Ca3SiO5生成;在温度为1450℃时,Ca3SiO5生成量最高达58%。此时铁被完全还原,铁的还原对Ca3SiO5的生成有影响。(2)连续升温实验温度为1250℃~1450℃时,铁的还原率均在90%左右;当配碳量为理论量的3倍、还原温度为1250℃、还原时间为120min条件下,铁的还原率高达91%。低浓度CO气氛,不利于单质铁生成;1250℃连续升温实验中,没有检测到Ca3Si O5生成。(3)在保证还原性气氛下,分阶段升温实验中设定首阶段设定温度为1000℃,保温时间为120min,第二阶段温度1450℃,保温时间为60min。反应同时生成了Fe和Ca3SiO5,铁还原率为88%,Ca3Si O5含量可达42%。二价铁离子占据Ca3SiO5的晶格,是导致Ca3SiO5难以生成的主要原因。(4)Ca3SiO5生成的适宜温度为1450℃。冷却速率对Ca3Si O5和Ca2Si O4的影响很大。随炉冷却时,由于β-Ca2Si O4晶型向γ-Ca2SiO4晶型转变,体积增大,发生了粉化现象;快速冷却时,由于在Ca3SiO5分解温度1250℃和Ca2SiO4晶型转变温度525℃停留时间短,从而使Ca3SiO5和β-Ca2Si O4能够保留到常温下。铁矿石直接还原提铁同时制备胶凝材料在理论及实验条件下是可行的,这对实现铁矿石尤其是贫杂铁矿石高效利用,缓解国内铁矿资源压力,节能减排提供了理论参考。
[Abstract]:The total reserves of iron ore in our country are sufficient, but the ore grade is not high, there are many poor complex iron ores, and the ore dressing is difficult, so it is difficult for the conventional ironmaking process to make efficient use of it. With the increasing decrease of rich ore reserves, the trend of future development should consider how to realize the efficient ecological utilization of lean iron ore resources, that is, to utilize not only the iron and valuable metal resources, but also the gangue components thereof. Therefore, it has important practical significance and application value to explore a kind of comprehensive utilization technology with reliable technology and reasonable economy, which can realize energy saving and emission reduction and reduce pollution. In this paper, hematite was used as raw material and carbon powder as reducing agent to study iron extraction by direct reduction of iron ore and preparation of cementitious material. The phase equilibrium of direct reduction process was calculated by FACTSage software, and the possibility of synergistic reaction between iron ore and cementitious material under different thermodynamic conditions was discussed. Then the experiments of direct reduction were carried out by means of continuous heating method and stepwise heating method. The reaction temperature, reaction time, ratio of reducing agent and reducing atmosphere were studied. The influence of cooling mode on the reduction rate of direct reduction iron and the formation rate of Ca3SiO5, the main component of cementitious material, and the formation mechanism of Ca3SiO5 were discussed. The results obtained are as follows: (1) the thermodynamic calculation results of the synergistic experiments show that the recovery rate of Fe2O3 direct reduction iron in hematite increases with the increase of carbon content at a temperature of 1250 鈩，

本文编号：1916866