Influence Of Rare-earth Oxides On The Compositions And Properties Of Baiyanobo Iron Ore Pellets

The baiyanobo iron used by Baotou iron and steel company is a kind of concentratedore,and contains abundant rare earth resources.In recent years, science and technologyworkers rely on baiyanobo ore to explore the interactions between rare earth and sinter.Butthe study about pellets are few.As the main raw material for ironmaking, pellets have manyadvantages,such as a uniform particle size, high grade, good reducibility and so on, theamount about pellet application is also increasing day by day in the blast furnaceuse.Researching mutual influence between rare earth and baiyanobo ore pellets hasimportant guiding significance to the producting and using for baotou steel special orepellets.This study takes Fe2O3and embellish ore as the main raw material in blast furnaceiron-making process,CeO2as rare earth additives, and design the technical route includingthe briquetting, preheating, roasting, and reduction.Aiming to the sample preheated,roasted and reduction,I use mineral microscopic observation, SEM, EDS and XRD analysismethod to explore the pressure of the changing rule of the phase composition andmicrostructure;Use the "method for determination of the relative free expansion index ofiron ore pellets (GB/T13241-91)" to assess the briquetting reduction rate;Use pelletcompression strength test device to detect the strength after the period of preheatingand roasting. Based on research contents,I analyse the influence of CeO2on Fe2O3andthe finding provide the theory evidence for baiyanobo ore.The results show that Ce-Fe-O solid solution was formed in preheated briquettesamples at511℃,which promoted the conection between Fe2O3grains and thus enhancedthe compressive strengh of preheated briquettes from8.75KN to12.58KN.The Ce-Fe-Osolid solution desoluted and decomposed at1070℃,and the high-melting-pointed CeO2itdecomposed existed between Fe2O3grains.CeO2prohibited the growth of crystal shocksbetween Fe2O3grains.As a result of that,the compressive strength of sintered briquettesamples decrease with CeO2contents from84.32KN to74.85KN.Found through experiments that when Fe2O3was reduced by CO some CeO2entered iron oxide lattice,and a solid solution formed which greatly promoted the reduction from Fe2O3to FexO, andinhibited the reduction from FexO to Fe，reduces the volume expansion of Fe2O3reductionto Fe3O4.When the content of CeO2is sufficient,part of CeO2promotes the formation ofCeFeO3,which finally makes reduction swelling changes with the addition of CeO2.Whenthe content of CeO2is5%,the reduction swelling of Fe2O3samples and baiyanobo iron oresamples reaches their lowest points,which is respectively13.66%and8.26%.