(1. 北京科技大学 土木与环境工程学院,北京 100083; 2. 清华大学 环境学院,北京 100084)
摘 要: 针对内配煤直接还原钛磁铁矿引入灰分和杂质从而降低钛产品品位的问题,利用包埋法进行直接还原,将无碳球团包埋在煤中,并分别以萤石和硫酸钠为添加剂,探讨此工艺的可行性及添加剂对还原的影响。结果表明:利用此工艺可实现铁还原的同时获得高品位钛产品的目标,且添加硫酸钠的效果优于添加萤石的效果;添加适量的萤石或硫酸钠均促进钛磁铁矿的还原,钛矿物由含钛低的钛铁尖晶石向含钛高的钛铁矿和亚铁板钛矿转变。金属铁颗粒长大有利于钛铁分离并分别富集,钙长石、霞石和FeS的形成是分别促进铁颗粒长大的原因,但添加过量的萤石和硫酸钠导致还原生成的金属铁聚集相连,阻碍气体扩散,不利于含钛矿物的还原。
关键字: 海滨钛磁铁矿;直接还原;钛铁分离;萤石;硫酸钠
(1. School of Civil and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2. School of Environment, Tsinghua University, Beijing 100084, China)
Abstract:The problem of coal-based direct reduction of titanomagnetite ore is that the coal ash and impurities are disadvantageous to obtaining a high-grade titanium product. To solve this problem, this study used embedding direct-reduction where pellets without coal were embedded under the coal to be reduced and fluorite and sodium sulfate were used as additives, respectively. The purpose is to demonstrate the feasibility of this process and study the effect of additives on the reduction. The results show that good direct reduction iron powder(DRIP) and titanium concentrate may simultaneously be achieved through this process, and addition of sodium sulfate is more effective than that of fluorite. The suitable addition of fluorite and sodium sulfate are conducive to the reduction of titanomagnetite, the ulvospinel are further reduced to ilmenite and ferrous pseudobrookite. The metallic iron particles grow up when the additives are added, and the reason is that the generation of anorthite, nepheline and FeS are beneficial to the growth of iron particles, respectively. However, a metallic iron shell is formed by the excess additives, which inhibits the reduction gas from entering into the pellets and the reduction of titanomagnetite.
Key words: beach titanomagnetite; direct-reduction; titanium and iron separation; fluorite; sodium sulfate