Basic Research On The Leaching Behavior Of Vanadium-bearing Steel Slag With Titanium White Waste Acid

Vanadium-titanium magnetite is rich in vanadium and titanium,which is an important strategic resource in China.In the process of vanadium extraction and titanium production,it will produce two kinds of industrial wastes,namely titanium white waste acid and vanadiumbearing steel slag.Extracting vanadium from vanadium-bearing steel slag with titanium white waste acid can efficiently recover vanadium resources in vanadium-bearing steel slag,and vanadium-bearing steel slag can neutralize waste acid.While treating waste with waste,huge economic benefits are also produced.In this paper,vanadium-bearing steel slag and titanium white waste acid produced in the process of extracting vanadium resources and preparing titanium dioxide from vanadiumtitanium magnetite in Panxi area were used as raw materials.The thermodynamic principle of leaching vanadium-bearing steel slag by titanium white waste acid was studied,the orthogonal,pressure and atmospheric pressure experiments were carried out,and the kinetics of the leaching process is studied.The main research contents and experimental results are as follows.(1)The phase analysis of vanadium-bearing steel slag shows that the main phases of vanadium-bearing steel slag are dicalcium silicate,tricalcium silicate and dicalcium ferrite,and vanadium is mainly dispersed in each phase in the form of V(Ⅳ)and V(Ⅴ)which are soluble in acid.Thermodynamic analysis of leaching process shows that vanadium exists in the form of V3+,VO2+and VO2+in aqueous solution.It is theoretically proved that vanadium-bearing steel slag can be directly extracted with titanium white waste acid without roasting.(2)The order of influencing factors determined by orthogonal experiment was as follows:initial acidity>L/S>time>speed>temperature.Pressure conditions have a certain promotion effect on vanadium leaching,but high initial acidity is still needed to achieve efficient vanadium leaching.Atmospheric pressure conditions are more conducive to industrial practice.The optimal process conditions were as follows:initial acidity 300 g·L-1,L/S 9:1,time 60 min,temperature 343K,speed 150 r·min-1.Under this process condition,the vanadium leaching rate was 92.61%,and the vanadium concentration in the leaching solution was 1.11 g·L-1.Subsequently,vanadium and impurity elements could be separated by chelating extraction.The main component of leaching residue is calcium sulfate dihydrate,which can be used as retarder of cement.(3)The kinetic experiment results show that the leaching process of vanadium conforms to the ’the kinetic model of liquid-solid leaching with solid product layer’.The vanadium leaching rate is controlled by the mixture of interfacial chemical reaction and product layer diffusion.The apparent activation energy of the reaction is 8.517 kJ·mol-1.Finally,the kinetic equation of vanadium leaching in the process of titanium dioxide waste acid leaching of vanadium-bearing steel slag is established.(?)...