Experimental Study On Gaseous Selective Reduction Of Baiyun Obo Nb-bearing Iron Ore Powder

This experimental study on the rule of Nb-bearing iron ore powder has been selective-reducted of hydrogen and carbon monoxide in the homemade diffusion bed tubular resistance furnace that gas blown from the bottom, under the different reduction time and temperature. They have a common point with the increase of reduction temperature and time, both of the reduction degree and metal rate of the ore powder improved significantly, geting the950℃is the best reduction temperature. The different point is:used H2reduced the ore powder for2h the reduction degree can reach90.98%, the metal rate can reach86.47%, used H2reduced the ore powder for reduced3h the reduction degree can reach94.07%, the metallization rate can reach91.11%. This reduction sample can be seen that metallic iron presents the density of granular structure, is mainly composed of metallic iron, ferrous oxide, fayalite and glass phase, reduced considerable metallic iron. CO reduced the Nb-bearing iron ore powder under the2.5h/950℃conditions, both of the reduction degree and metal rate got relatively high, the reduction degree can reach76.59%, the metallization rate can reach64.89%, after CO reduction the sample can see that metallic iron presents the flaky structure, is mainly composed of metallic iron, ferrous oxide and fayalite, all the iron oxide have not been fully reduced. The experimental found that adding LiCl catalyst can promote the H2reduction reaction, both of the reduction degree and metallization rate improved significantly, almost all of the iron oxide has been reduced to metallic iron, the results show that adding LiCl within the range of0.43%-1.00%in the70g Nb-bearing iron ore powder the catalytic effect is most obvious, especially adding0.71%LiCl the catalytic effect is the best, compared with the same conditions without catalyst, the reduction degree increased from85.04%to95.82%, the metallization rate increased from77.56%to93.73%. The study found that adding Li2CO3catalyst can promote the CO gas’s reduction reaction, adding Li2CO3within the range of0.43%-1.00%in the70g Nb-bearing iron ore powder the catalytic effect is most obvious, especially adding0.71%Li2CO3catalyst is the best, compared with the same conditions without catalyst, the reduction degree increased from67.63%to78.30%, the metallization rate increased from51.45%to67.45. Used the unreacted core model to make the kinetics analysis, the results show:at800℃-950℃the reduction reaction’s restrictive link was controlled with both of the interface chemical reaction and internal diffusion, the activation energy in the reaction was19.106kJ.mol-1, the frequency factor was0.0023, the Arrhenius equation was:K+=0.0023exp(-19106/8.314T) or Lnk+=-19.106/RT-6.0545...