Research On Physicochemical Properties And Phase Diagram Of Vanadium Slag

During the vanadium recovery process in converter, the vanadium slags’ hightemperature physicochemical properties impact the vanadium oxidation and extractionefficiency directly, also ensure the vanadium recovery process go on smoothly. Take themelting temperature and viscosity for examples, they characterized the smelting andflowing properties of vanadium slags, and have great effect on the heat and masstransfer between the slag and hot metal. In the operation, they also have great influenceon vanadium enriching speed, quality of vanadium slag and slag and iron separationmanipulation. The composition of vanadium slags impact vanadium’s occurrence andphase structure, which determined the high temperature physicochemical properties ofthe slag. Researching the relationship between composition, structure andproperty,establishing the phase diagram of the slag,are the foundamental of vanadiumrecovery technology.While till now for the converter vanadium slag, the researchs aboutthe relationship between composition, structure and property are very rare,and also lackthe basic data of phase diagram. So basing on the vanadium recovery technology andthe characteristics of the converter slag of the Panzhihua steel,this dissertationresearched the changes of the phase structure, physicochemical properties which aroseby the composition,also drew the phase diagram with these results.These research haveimportant effect on optimizing vanadium recovery technology and enhancing thequality of vanadium slag.During this study,the changing trend of the vanadium slag’s composition and phasestructure was researched by using the xrd numeral token and high-temperaturehardening experiment for the first time. Against the character of the converter vanadiumslag, this thesis modified the implement to test the melting temperature and viscosity ofthe vanadium slag, also discussed the changing mechanism of the properties andcomposition. In another hand, the section phase diagrams of FeO-SiO₂-V₂O₃systemwas calculated and drawn, using the modified quasi-chemical solution theory. The mainresearch results are as follows:①The main phases of the converter vanadium slag are spinel and olivine. Spinelis vanadium’s main occurrence. When FeO/SiO₂＜1.5, the content of the spinelincreased with the improving of V₂O₃in the system. When FeO/SiO₂is higher, contentof spinel reduced with the improving of V₂O₃, and have tended to be the same value. ②The melting temperature of vanadium slag in this research is between1300°C～1400°C generally. The V₂O₃can increase melting temperature, whileFeO/SiO₂decreases them.③Below1365°C,viscosity of the vanadium slags is3.5pa s at least. At the sameFeO/SiO₂, when V₂O₃added, the slag turned basic to acid. When FeO/SiO₂increased,the complex ion groups disintegrated, which caused the system’s viscosityreducing.When V₂O₃increased, there are more uneven particles which increased theviscosity of the system.④The isothermal section of FeO-SiO₂-V₂O₃system under1200°C、1300°C、1400°C was calculated and drawn. Follow them, we know at1200°C, most of thematerials are solid. Only when FeO/SiO₂=2near the SiO₂region there are little liquidregion. Till1300°C, liquid region increased, and there are some liquid surface near thehigh FeO angle.1400°C, the liquid area increased at FeO angle.There is no solid of FeO.At the area of20%＜V₂O₃＜37%and1.2＜FeO/SiO₂＜2.5, liquid phase area increaseswith the increasing of the temperature, which is benefit for vanadium extraction.