In-situ Doping Of Titanium-bearing Blast Furnace Slag With Different Metal Elements And Its Effect On Direct Extraction Of Perovskite

In the smelting process of Panzhihua Steel's blast furnace,most of the high-value symbiotic metal elements such as titanium and niobium enter the slag phase,forming titanium-containing blast furnace slag containing about 24%of TiO₂.Titanium-bearing blast furnace slag is a valuable secondary resource.Due to the complex mineral phase,it is difficult to use it effectively.Aiming at the problem of the utilization of titanium-containing blast furnace slag in Panzhihua Iron and Steel Co.,although many scholars have carried out a lot of research and even established some demonstration industrialization routes,due to many factors such as resources,environment and social economic benefits,it is still a significantchallenge in the utilization of slag high value resources.The essential reason for the thorny problem is that there are currently no ecomonically facilities for efficiently separating multiple valuable components in titanium-containing blast furnace slag.In this thesis,the Titanium-bearing blast furnace slag of Panzhihua Iron and Steel Co.,Ltd.is used as the research object.The titanium-containing blast furnace slag is doped in situ by metal oxides MoO₃,WO₃,ZrO₂,Nb₂O₅ and PbO₂,respectively,and then sodium carbonate is used for high-temperature heat modification to reconstruct the titanium blast furnace slag mineral phases,and then the perovskite is directly extracted by dilute hydrochloric acid leaching.XRD,SEM,XRF and FT-IR systems were used to study the composition of mineral phases and the occurrence of related elements in each stage.Finally,the application of directly extracted perovskites was explored.The rule of direct extraction of perovskite from titanium-containing blast furnace slag by metal element is sought,which provides a theoretical basis for the optimization of in-situ resource endowment of titanium-containing blast furnace slag.The specific research work and conclusions of this thesis are as follows:(1)The titanium-containing blast furnace slag was doped in situ by using MoO₃,WO₃,ZrO₂,Nb₂O₅ and PbO₂,and kept at 1500°C for 1 h,and then cooled with the furnace.The results show that the Mo element cannot be doped into the perovskite phase,and the W,Zr,Nb and Pb elements can be doped into the perovskite phase.Among them,with MoO₃ and WO₃ doped,the diopside phase does not change.However,the diopside phase disappears in which the samples doped with PbO₂,ZrO₂and Nb₂O₅,and the forsterite phase is formed.Doping with MoO₃,WO₃ and ZrO₂will form the enrichment of the respective metal elements,and the doping amount will increase,and the enrichment is more obvious.The samples doping with MoO₃,WO₃and ZrO₂ form CaMoO₄,CaWO₄,Ca₂Zr₅Ti₂O₁₆,respectively.(2)High-temperature thermal modification of titanium-containing blast furnace slag by in-situ doping with relevant metal elements by sodium carbonate,and kept at1500°C for 1 h,and cooled with the furnace.The results show that magnesium aluminate spinel and diopside or forsterite which are difficult to be acidified by dilute hydrochloric acid are reconstituted to be periclase and aluminosilicate.Mo and Pb elements cannot be doped into the perovskite phase.The W,Zr and Nb elements can be doped into the perovskite phase.CaMoO₄ and CaWO₄ reconstitute to be Na₂MoO₄and Na₂WO₄,respecitivily.While the PbO₂ doped slag appears the separated PbO.And the slag with 30%ZrO₂ doped reconstituted to be CaZrO₃.(3)During the dilute hydrochloric acid leaching process of the related metal elements doped reconstituted slag,aluminosilicate and periclase can be completely acidified Na₂MoO₄ and Na₂WO₄ can be completely acidified by dilute hydrochloric acid.PbO is acidified to be slightly soluble in Pb Cl₂ dissolved in water and dilute hydrochloric acid.CaZrO₃ in 30%ZrO₂ doped reconstitution cannot be acidified by dilute hydrochloric acid.(4)The preliminary application of the doped metal element perovskite was carried out.The experimental results show that the absorption of the doped perovskite in the visible region increases.High grade perovskites have greater physical adsorption.A small amount of WO₃ and PbO₂ doping can improve the photocatalytic response of the perovskite directly extracted from the titanium-containing blast furnace slag,which can greatly enhance and stabilize the transient photocurrent.(5)The titanium-containing blast furnace slag can be directly doped with a higher grade of perovskite by doping a small amount of metal elements.The excessive doping will affect the grade of perovskite.(6)Ca₂Zr₅Ti₂O₁₆ was reconstituted into CaZrO₃ during the process of reconstituting for the 30%ZrO₂ in situ doped slag by sodium carbonate.CaZrO₃ is present in the 30%ZrO₂ doped reconstituted slag in the form of being completely coated with perovskite.In summary,this paper applies in-situ doping of metal elements in Panzhihua Iron and Steel Co.,Ltd.,and directly extracts perovskite doped with metal elements.The in-situ doping,sodium carbonate modification and dilute hydrochloric acid leaching process are studied.The evolution of mineral phase and the occurrence of related elements and the direct extraction of perovskite applicat ion are explored.The research results provide a theoretical basis for the in-situ resource endowment optimization of Titanium-bearing blast furnace slag and the efficient separation of titanium components in titanium-containing blast furnace slag,and also provide a new way for the high-value resource utilization of titanium-containing blast furnace slag.