【作者】 高伟；

【导师】 马北越；

【作者基本信息】 东北大学 ， 材料与化工（专业学位）， 2023， 硕士

【摘要】 钒钛磁铁矿是一种多金属元素共生的复合矿,含有钒、钛和铬等重要战略金属元素,具有很高的综合利用价值。合理开发利用钒钛磁铁矿的潜在价值,对于促进国民经济的发展具有重要意义。但生产实践表明,钒钛磁铁矿冶炼过程中所形成的钒渣对炉衬耐火材料侵蚀严重,导致提钒转炉炉衬寿命明显短于冶炼普通铁矿时寿命。频繁更换炉衬不仅会增加生产成本、扰乱生产节奏,还会对钢材产品质量产生负面影响。因此,有必要进一步提高炉衬耐火材料抗钒渣侵蚀的性能。同时,提钒转炉大多使用MgO-C耐火材料作为炉衬,其在使用过程中易与氧气或氧化性熔渣反应,形成多孔氧化层,后续的熔渣与MgO-C耐火材料界面反应实则是熔渣与氧化层间的反应。然而,钒渣与炉衬耐火材料间的相互作用机理尚不明确,有待进一步研究。论文首先制备了不同钒、钛含量的熔渣(V0T0、V10T0、V20T0、V0T10、V10T10和V20T10),研究了钒、钛含量对熔渣物理化学性质的影响;同时制备了不同ZrB2添加剂含量的MgO-C耐火材料氧化层(Z1(无ZrB2)、Z2(2%ZrB2)),考察了添加剂含量对氧化层气孔率、物相组成及微观形貌的影响。随后研究了熔渣在氧化层基板上的润湿和侵蚀行为。利用熔点熔速测试仪原位观测熔渣在耐火材料表面的润湿、铺展过程,并提取熔渣的表观外形参数,如直径、高度和润湿角。利用扫描电镜和能谱仪对侵蚀后微观形貌进行分析,研究钒渣与MgO-C耐火材料氧化层间的界面反应行为与机理,得到结果如下:(1)随着原始渣中V2O3质量分数的添加,熔渣VOT0、V10T0和V20T0与MgO-C耐火材料氧化层Z1试样和Z2试样间的接触角逐渐减小,V0T10、V10T10和V20T10与Z1试样和Z2试样间的接触角先增加后减小,熔渣中V2O3的添加量越高,接触角越小。添加10%的TiO2可减小耐火材料与熔渣之间的接触角。(2)熔渣侵蚀Z1和Z2试样后,对界面层进行EDS面扫描分析可知:熔渣物相中都存在橄榄石相2(Mg,Fe,Mn)O·SiO2和(Fe,Mg,Mn)O固溶体。当不添加TiO2时,V0T0物相中存在高熔点相,如(Mg,Mn)O·Fe2O3,随着V2O3的添加量增加,V10T0和V20T0物相中相继出现低熔点相,如MgO·V2O5相、MnO·V2O5相、Fe2O3·V2O5相等,熔渣V0T0、V10T0和V20T0的熔点逐渐降低。当添加10%的TiO2时,随着V2O3的添加量增加,熔渣V0T10、V10T10和V20T10物相中逐渐出现钛铁复合氧化物、MnO·V2O5、MgO·V2O5、Fe2O3·V2O5等低熔点相。熔渣V0T10、V10T10和V20T10熔点逐渐降低,低熔点相导致含钒钛熔渣侵蚀MgO-C耐材氧化层更严重。(3)Z2试样相对于Z1试样体积密度增大,显气孔率减小,这主要是由于Z2试样中的ZrB2添加剂在高温氧化过程中生成了低熔点相的Mg3B2O6,其填充了部分石墨和树脂氧化和分解所遗留下的孔隙。但侵蚀实验表明,Z2试样的抗渣侵蚀性能较Z1试样差,这亦是由于Z2试样本身存在低熔点相所致。更多还原

【Abstract】 Vanadium-titanium magnetite is a complex ore that contains multiple strategic metal elements,such as vanadium,titanium,and chromium,with high comprehensive utilization value.The rational development and utilization of the potential value of vanadium-titanium magnetite are of great significance for promoting the development of the national economy.However,the production practice has shown that the vanadium slag formed during the smelting process of vanadium-titanium magnetite severely corrodes the refractory lining material,leading to a significantly shorter service life of the lining for the converter used in vanadium extraction than that used for smelting common iron ore.Frequent replacement of the lining not only increases production costs and disrupts production rhythm but also has a negative impact on the quality of steel products.Therefore,it is necessary to further improve the anti-corrosion performance of refractory lining materials to vanadium slag.Meanwhile,most vanadium extraction converters use MgO-C refractory materials as the lining,which is prone to react with oxygen or oxidative slag during use,forming a porous oxide layer.The subsequent reaction between the slag and the MgO-C refractory material interface is actually the reaction between the slag and the oxide layer.However,the interaction mechanism between vanadium slag and refractory lining materials is not yet clear and requires further research.The present study first prepared slag samples with different vanadium and titanium contents(V0T0,V10T0,V20T0,V0T10,V10T10,and V20T10)and investigated the effects of vanadium and titanium contents on the physicochemical properties of the slag.Concurrently,MgO-C refractory oxide layer samples with varying ZrB2 additive contents(Z1(without ZrB2),Z2(2%ZrB2))were prepared to investigate the effects of additive content on the porosity,phase composition,and microstructure of the oxide layer.Subsequently,the wetting and erosion behavior of the slag on the oxide layer substrate were studied.The wetting and spreading process of the slag on the refractory material surface was observed in situ using a melting point melting rate tester,and the apparent shape parameters of the slag,such as diameter,height,and wetting angle,were extracted.The microstructure after erosion was analyzed using scanning electron microscopy and energy dispersive spectroscopy to investigate the interface reaction behavior and mechanism between the vanadium slag and the MgO-C refractory oxide layer.The results are as follows:(1)As the mass fraction of V2O3 in the raw slag increases,the contact angles between the MgO-C refractory oxide layer Z1 and Z2 samples and the slag,V0T0,V10T0,and V20T0 gradually decrease.For V0T10,V10T10,and V20T10,the contact angles first increase and then decrease with respect to both Z1 and Z2 samples.The higher the amount of V2O3 added to the slag,the smaller the contact angle becomes.The addition of 10%TiO2 can reduce the contact angle between the refractory material and the slag.(2)EDS surface scanning analysis of the interface layer after the slag erosion of the Z1 and Z2 samples revealed the presence of olivine phases 2(Mg,Fe,Mn)O·SiO2 and(Fe,Mg,Mn)O solid solution in the slag phase.When TiO2 was not added,high melting point phases such as(Mg,Mn)O·Fe2O3 were present in the V0T0 phase.As the amount of V2O3 added increased,low melting point phases,such as MgO·V2O5 phase,MnO·V2O5 phase,and Fe2O3·V2O5 phase,successively appeared in the V10T0 and V20T0 phases,and the melting points of the V0T0,V10T0,and V20T0 slags gradually decreased.When 10%of TiO2 was added,with the increasing amount of V2O3,low melting point phases,such as titanium-iron composite oxide,MnO·V2O5 phase,MgO·V2O5 phase,and Fe2O3·V2O5 phase,gradually appeared in the V0T10,V10T10,and V20T10 phases.The melting points of the V0T10,V10T10,and V20T10 slags gradually decreased,and the low meltingpoint phases led to more severe erosion of the MgO-C refractory oxide layer by the vanadium and titanium-containing slag.(3)The Z2 sample exhibited an increase in bulk density and a decrease in apparent porosity compared to the Z1 sample,mainly due to the formation of a low melting point phase,Mg3B2O6,generated by the ZrB2 additive in the Z2 sample during the high temperature oxidation process.This phase filled some of the pores left by the oxidation and decomposition of graphite and resin.However,the erosion experiments showed that the slag resistance of the Z2 sample was worse than that of the Z1 sample,which was also due to the presence of the low melting point phase in the Z2 sample itself.更多还原