钒渣钙化焙烧热分析及物相转变机理分析

Thermal analysis and phase transition mechanism analysis of calcified roasting of vanadium slag

针对目前钒渣钙化焙烧尚未有系统热分析的问题,本文在钒渣焙烧过程热力学分析的基础上,对钒渣(掺入CaCO_(3))、钒渣(掺入CaO)焙烧进行了热重分析(TG)和差示扫描量热分析(DSC),并对焙烧过程中可能发生的各种物相转变机理进行了分析,得到以下主要结论。钒渣钙化焙烧过程中,在960℃范围内生成偏钒酸钙、焦钒酸钙和正钒酸钙的反应是可行的;钒渣钙化焙烧过程主要由四个相互衔接或者重叠的反应阶段组成,即金属Fe氧化阶段,铁橄榄石氧化、分解阶段,尖晶石氧化分解和钒酸盐形成阶段,硅钙反应和辉石分解阶段;焙烧过程物相转变的控制温度为:350~700℃范围内金属铁氧化生成,500~750℃范围内铁橄榄石氧化和分解,500~900℃范围内尖晶石氧化分解且生成钒酸盐,硅钙反应和辉石分解温度一般在900℃以上。本研究结果可为生产现场温度控制提供理论支撑。

In view of the lack of systematic thermodynamic analysis and thermal analysis of calcium roasting of vanadium slag,thermogravimetric analysis(TG)and differential scanning calorimetric analysis(DSC)were conducted on the roasting process of vanadium slag mixed with CaCO_(3) or CaO.The phase transformation mechanisms during roasting process were analyzed,and the main conclusions were drawn as follows.It is feasible to produce calcium metavanadate,calcium pyrovanadate and calcium orthovanadate in the range of 350-960℃during calcified roasting of vanadium slag.The calcination process of vanadium slag is mainly composed of four reaction stages which are interconnected or overlapping,namely,metal Fe oxidation stage,iron olivine oxidation and decomposition stage,spinel oxidation and decomposition stage of vanadate formation stage,silica-calcium reaction and pyroxene decomposition stage.The control temperature of phase transformation in the roasting process is:the oxidation of metal iron in the range of 350-700℃,the oxidation and decomposition of iron olivine in the range of 500-750℃,the oxidation and decomposition of spinel in the range of 500-900℃and the decomposition temperature of silica-calcium reaction and pyroxene is generally above 900℃.These results can provide theoretical support for temperature control in production site.