Mineral Transition Of Fe,Al-Associated Ore During Melting Reduction Process

Due to the rapid development of steel and aluminium industry in China,the domestic iron and aluminum resource is insufficient,and the development of new aluminum iron resources is imminent.In China,the iron-bearing resources reserve is huge,However,the content of iron oxide and alumina is relatively less in iron-bearing resources.Only the comprehensive utilization of the iron,aluminium,etc of valuable elements has great economic value.It is a key path for the sustainable development of our bauxite resource and ore resource.The process of "rotary heath furnace reduction-calcium aluminate slag-iron separation at high temperature-leaching alumina from calcium aluminate slag" was uesd in the article.The raw material include high iron bauxite,coal and AR calcium carbonate.Systematic research on the melting points reduction process,under different conditions almandine,phase in the formation and shift of iron ores,calcium aluminate slag' leaching and powder performance.And research on the effect of calcium content and coal content on prereduction stage for calcium aluminate slag's phase shift and FeO content on melting points reduction stage.The main research results are as follows.Different molar ratios of CaO unbonded with SiO₂ to Al₂O₃?C/A?in prereduction stage has effect on phase composition of calcium aluminate slag when melting reduction C/A is the same.The peritectic reaction between 2CaO Al₂O₃·SiO₂ and CaO plays a leading role.When the prereduction C/A=0.4,CaO ·Al₂O₃ is exist in the calcium aluminate slag on melting points reduction stage.But it disappear when the prereduction C/A is increased.12CaO·7Al₂O₃ content get the minimum value when the prereduction C/A=0.4.With the increase of C/A,12CaO·7Al₂O₃ content is stable at around 20%,the content of 2CaO·SiO₂ and 2CaO Al₂O₃·SiO₂ increased at first and then decreased.When Prereduction molar of C to 0 in iron oxide?C/O?increased from 0.5 to 1.6 at the same melting reduction C/O,FeO content of prereduction pellet decreased from 9.7%to 7.09%.Lower prereduction pellet FeO content raise the slag melting temperature and viscosity.Reduction effect get worse.Overmuch FeO is the burden of melting reduction.FeO content of calcium aluminate slag is lowest when the prereduction C/O is 0.8.When C/A increased from 1.4 to 1.8,2CaO·Al₂O₃·SiO₂ content decreased continuously,Reduction effect get worse,and FeO content of calcium aluminate slag was increased.When C/A increased from 1.4 to 1.7,12CaO·7Al₂O₃ content increased.If C/A get higher,the content would be less,and the the lattice constant of 12CaO·7Al₂O₃ decreased at first and then increased.Improving C/A is conducive to conversion between ?-2CaO SiO₂ and?-2CaO·SiO₂,but the reason is not clear.C/O has little impact on phase conversion of calcium aluminate slag.When C/O increased from 0.6 to 1.2,Iron accumulation ability becomes poor.For C/0=1.2,iron phase dispersed into multiple small iron bead,residual FeO get more and more in slag,calcium aluminate slag alumina leaching ability becomes poor.When melting temperature increased from 1450? to 1450?,12CaO·7Al₂O₃ content gradually reduce until disappear,in contrary 3CaO Al₂O₃ is generated.Calcium aluminate slag alumina leaching ability becomes poor.When melting temperature is 1450?,the iron phase gathered together as sponge iron,if improve melting temperature continuely,the iron gathered together as a big iron bead.Above 1500?,melting temperature makes slag residual FeO in reduced.Extend the time of heat preservation,phase species remains the same,2CaO·Al₂O₃ ·SiO₂ content is slightly lower,12CaO·7Al₂O₃ lattice decreased constantly.FeO content in slag under the condition of extended holding time will reduce gradually,and reduce rate is fastest between 30 min?45 min.When A/S are 1.9 and 2.2,calcium aluminate slag powder completely,and the powder rate is above 98%.Increasing A/S continuely will make powder rate become lower.Powder would decrease to 14.88%if A/S was 2.96.By XRD spectrum semi-quantitative calculation,the powder ability of calcium aluminate slag begin to be power when the content of 2CaO·SiO₂ is below 18.17%.