Optimization And Affecting Mechanism Of Blast Furnace Slag System For Smelting Vanadium-titanium Magnetite

Vanadium-titanium magnetite is an important multiplex coexistence iron ore and has high comprehensive utilization value.Currently,the process that is blast furnace-vanadium extraction process in BOF-semisteel steelmaking is adopted to make full use of vanadium-titanium magnetite.Because of the characteristics of blast furnace slag that were ropy,poor fluidity,poor stability and foamy slag in smelting vanadium-titanium magnetite process,it is difficult for blast furnace production to reach the level of strengthening smelting.Therefore,the slag samples were confected by using pure chemical reagents,based on the components of practical blast furnace slag of vanadium-titanium magnetite provided by a domestic enterprise.In this study,the effects of slag components on the metallurgical properties and phase components of slag system were studied firstly.Then the slag components of best comprehensive metallurgical properties indexes were obtained through taguchi method and comprehensive weighted method.At last,the metallurgical properties of six different blast furnace slags of vanadium-titanium magnetite were researched.The conclusions were as follows:(1)With increase of binary basicity,tm of slag was increased,?0 and ?h were decreased,and thermostability and chemical stability became better.The main phase of each slags was melilitite.As increasing MgO content,tm of slag had increase,?0 and ?h showed a decreased tendency,thermostability was worse first and then got better,and chemical stability got worse.The slag system that main phase was melilitite transfered from melilitite primary crystal field to spinel primary crystal field.With increase of Al2O3 content,tm and ?h of slag were rised,but?0 was first increased and then decreased,thermostability and chemical stability became worse.The slag system that main phase was melilitite transfered from melilitite primary crystal field to spinel primary crystal field.When increased the Ti02 content,tm of slag was first decreased and then increased,both ?0 and ?h were decreased,thermostability was better first and then got worse,and chemical stability got better.The slag system that main phase was melilitite transfered from melilitite primary crystal field to perovskite primary crystal field.With increase of V2O5 content,tm and ?h of slag were first decreased and then increased,but ?0 was increased.(2)Under the factor levels condition of orthogonal optimization test,the order of slag components affecting comprehensive indexes of slag system respectively was the MgO content,binary basicity,TiO2 content,Al2O3 content.and V2O5 content.In order to obtain better comprehensive metallurgical properties of slag,the suitable components of BF slag system was as follows:binary basicity was 1.20,the content of MgO,Al2O3,TiO2 and V2O5 was 14.00%,11.00%,9.00%and 0.05%respectively.Compared to basic slag system and orthogonal test slag system,the viscosity of suitable slag system was lower,fluidity;thermostability and chemical stability became better.(3)With increase of TiO2 content,the tm of three different TiO2 content levels slags was gradually increased,the fluidity became better,?0 and ?h were decreased,thermostability and chemical stability were better first and then got worse.Meanwhile,melilitite in slag decreased sharply,pyroxene and perovskite in slag were rised.As increasing Al2O3 content,the tm,?0 and?h of three different Al2O3 content levels slags showed a increased tendency,the fluidity,thermostability and chemical stability were worse,and the sum of spinel in slag was more.