Dissolution And Reduction Behaviors Of Cr₂O₃ In TiO₂-bearing Blast Furnace Slag

There are almost ten billion tons of vanadium titano-magnetite in Panzhihua-Xichang area.Although the general vanadium titano-magnetite has formed a relatively mature BF technological process,but in Hongge iron ore mining,which has the most abundant reserves,the situation is opposite.Because of the high content of Cr2_O3?0.49%⁰.82%?in vanadium titano-magnetite in Hongge iron ore mining which is different from the general vanadium titano-magnetite when smelting by BF technological process.Therefore,it is significant for the research on reduction and dissolution behavior of Cr2_O3 in Ti-bearing blast furnace slag.On one hand,it can provide a theoretical basis for the development and utilization of high-Cr type vanadium titano-magnetite to ease the situation of China's iron ore dependence on imports in the future,on the other hand,it can also provide a reference for subsequent chrome vanadium separation method.According to combining the theoretical calculation and experimental method,this paper studies the dissolution and reduction behavior of Cr2_O3 in Ti-bearing blast furnace slag.The main conclusions are as follows:?1?The dissolution behavior of Cr2_O3 in Ti-bearing blast furnace slag:Theoretical calculation shows that the solubility of Cr2_O3 in the slag increases with the increasing of temperature,and the solubility of Cr2_O3 in the slag decreases with the increasing of basicity,the percentage of TiO₂,the percentage of Al₂O₃,the percentage of MgO,the percentage of FeO.?2?The reduction behavior of Cr2_O3 in Ti-bearing blast furnace slag:1)Theoretical calculation shows that reducted by CO without considering the activity of Cr,Cr2_O3 exist stably below 1520 K,Cr exist stably above 1520 K.Under the condition of invariable in composition of molten iron,the activity of Cr increased with the increase of temperature.When reducted by C,the reduction reaction order of resultants is Cr₃C₂ ?Cr₇C₃?Cr₂₃C₆ ?Cr with the increase of temperature.To reduce Cr2_O3 in the CaO-SiO₂-Al₂O₃?14%?-MgO?8%?-TiO₂-Cr2_O3?1%?slag by carbon in hot metal,when the temperature varies from 900? to 1600?,the percentage of Cr increases first then keeps unchanged;when the viscosity of the slag varies from 0.9 to 1.3,the percentage of Cr keeps unchanged;when the percentage of TiO₂ in the slag varies from 0% to 20%,the percentage of Cr keeps unchanged.That is because the reduction reaction has been done under this conditions.2)The reduction experiments was conducted at 1450 ?,it can be draw that the amount of Cr and Ti in the hot metal was increased with the increase of reaction time,the amount of Cr in the hot metal was decreased with the increase of TiO₂%;When the content of TiO₂ increased from 0% to 5%,the reduction rate of the initial stage increased,and when the content of TiO₂ increased from 5% to 20%,the reduction rate of the initial stage decreased;The theoretical results coincide with the experimental results.3)Based on the multi component coupling reaction kinetics model,the coupling kinetics model of Cr2_O3 reduction in blast furnace slag with 15 % TiO₂ content was established.It can be see that according to the calculate based on the experimental dates,the mass transfer coefficient of Cr and Ti in hot metal are 3.1×10-4 m/s,and the mass transfer coefficient of Cr2_O3 and TiO₂ in the slag are 1.55×10-5 m/s,the theoretical results have high degree of coincidence with the experimental dates by the multi component coupling reaction kinetics model,so it can be used to predict the percentage of Cr in hot metal reduction from Cr2_O3 in slags by carbon well.