镁化合物对钒钛磁铁矿精矿碳热还原的影响研究

Carbothermic Reduction of Vanadium Titanomagnetite Concentrate with Magnesium Compounds

以承德钒钛磁铁矿精矿（VTC）为研究对象，研究了不同镁化合物（MgCl2，MgSO4，Mg（OH）2，MgO）对钒钛磁铁矿在焦粉还原中的影响，探讨用镁化合物作为添加剂强化钒钛磁铁矿还原的可能性。气体分析结果表明含有不同镁化合物的VTC球团在1250℃下还原120min后，球团的还原度顺序为MgCl2〉MgO〉Mg（OH）2〉无添加剂〉MgSO4；MgCl2的添加有利于整个还原过程；MgSO4的添加能加快还原前期磁铁矿还原成浮氏体的过程，但会阻碍浮氏体还原成金属铁；而MgO和Mg（OH）2的添加有助于还原后期钛铁矿的还原。x射线衍射（XRD）及扫描电镜（SEM）、能谱分析（EDS）结果表明镁的添加，还原产物从亚铁板钛矿转变为钛酸镁，镁比铁更倾向于与钛结合，利于钛铁分离；但同时在还原过程中，镁聚集在未反应的内核中形成镁铁氧的固溶体阻碍铁的进一步还原，这是造成添加MgSO4降低VTC球团的还原度的主要原因。

Effects of magnesium compounds （ MgCl2 , MgSO4 , Mg（OH） 2, MgO） on carbonthermic reduction of the Chengde titano- magnetite concentrates （VTC） were investigated to explore the feasibility of adding magnesium compounds to improve the redueibility of VTC. The reaction gas analysis results showed that the order of reduction degree of VTC briquette containing different magnesium compounds was MgCl2 〉 MgO 〉 Mg（OH）2 〉 no additives 〉 MgSO4 after reducing 120 min at 1250℃. The addition of MgCl2 was beneficial to whole reduction process ; the addition of MgSO4 was favorable to the reaction of magnetite to wustite at the initial stage, but it also had disadvantageous effects on the stage of wustite reduced to metallic Fe; and the addition of MgO and Mg（OH）2 could enhance the reduction of ilmenite in the later stage. X-ray diffraction （XRD） and scanning electron microscope （SEM） analysis proved that magnesium titanate formed instead of FeTi2 05 at the presence of magnesium, which was advantageous to the separation of titanium and iron. Nevertheless, the addition of MgSO4 decreased the reduction degree of VTC briquette, which was mainly due to the formation of magnesium iron oxides by the enrichment of Mg in the unreacted core restricting the further reduction.