Na_2CO_3促进某硅质页岩中低价钒的钠化氧化作用研究

在对含钒硅质页岩添加NaCl进行氧化焙烧提钒过程中引入Na_2CO_3可促进钒的氧化和后续浸出。在对促进效果进行考察的基础上,通过对复合添加剂焙烧产物及浸出渣的化学成分、XRD及SEM-EDS等的分析,研究了Na_2CO_3的促进机理。结果表明:①在NaCl+Na_2CO_3(质量比为3∶2)与试验原料质量比为10%,焙烧温度800℃,焙烧时间180 min,焙烧产物在液固比10 mL/g、浸出温度80℃、浸出时间120 min条件下搅拌浸出(600 r/min),钒浸出率达到84.96%。②焙烧过程中,原料中的白云母、伊利石等矿物铝氧八面体晶格被破坏,转变为主要含元素Na、K、Al、Si、O的熔融颗粒并析出钠长石。Na_2CO_3增加焙烧原料碱度,使石英反应活性增强并与熔融颗粒共熔产生多孔颗粒。③加入NaCl和Na_2CO_3后,熔融颗粒及石英共熔产生的微孔结构及焙烧过程中充填于熔融颗粒间的长石形成的气相通道,均使焙烧料内部O2的扩散性增强,与低价钒接触几率增加,加速钒氧化进程,使钒氧化焙烧效果变好。

Promotion of Na2CO3 on Sodium Oxidation of Low Valence Vanadium during Roasting of Siliceous Shale

The addition of Na₂CO₃ in the process of sodium roasting of vanadium-bearing siliceous shale can promote the oxidation and leaching of vanadium. The promotion effect of Na₂CO₃ was investigated based on promotion effect by chemical composition analysis， XRD and SEM-EDS of roasting products and leaching residue from oxidation roasting with composite additive. The results showed that:① When the mass ratio of NaCl+Na₂CO₃ （3∶2 of mass ratio） to the raw material was 10%， the roasting temperature was 800 ℃， the roasting time was 180 min， the liquid-solid ratio was 10 mL/g， the leaching temperature was 80 ℃ and the leaching time was 120 min（stirring speed is 600 r/min）， the optimal leaching rate of vanadium was 84.96%.② During roasting， because of the destruction of Al-O octahedral lattice， the muscovite and illite in the raw materials were transformed into the melt particles containing Na， K， Al， Si and O. The addition of Na₂CO₃ increases the basicity of raw materials， enhances the reactivity of quartz and produces porous particles by co-melting with molten particles. ③With the addition of Na₂CO₃， the micropore structure produced by co-melting of melt particles and quartz and the gas channel formed by feldspar filling in the melt particles during roasting， enhanced the diffusivity of O₂， increased the contact probability with low-valent vanadium in ore， and accelerated the process of vanadium oxidation， and increased the oxidation roasted effect of vanadium.