Effect Of Sintering Process On Composition Struction And Gasification Dephosphorization Of Pre-reduction Sinter From Bayan Obo Iron Concerntrate

China's medium and high phosphorus iron ore resources are abundant,however,it is difficult to remove effectively due to the high phosphorus content.The phosphorus content of Baiyun Obo iron concentrate reaches 0.08%and mainly exists in the form of apatite.Therefore,the most critical step is to remove the phosphorus in the form of apatite.To date,several methods have been applied,such as beneficiation,gas-based reduction,microwave and leaching,the performance of which is unsatisfactory due to the low dephosphorization,extensive pollution,high consumption and so on.The pre-reduction sintering process with the characteristics of sufficient carbon addition,negative pressure and an elevated reaction temperature,can effectively remove phosphorus from iron ore.It is theoretically significant for the efficient utilization of medium and high phosphorus iron ore resources and the cost reduction of raw material for steel enterprises.Based on the existing status of P in the Bayan Obo iron ore concentrates,the effective separation of phosphorus mineral and gangue mineral,and the thermodynamic and kinetic mechanisms of dephosphorization,the sintering cup experiment of different carbon mixing ratio(5wt%,10wt%,15wt%,20wt%,25wt%)and Si O₂content(1wt%,2wt%,3wt%,4wt%,5wt%)was done to explore the composition,structure,gasification dephosphorization rate and metallurgical performance during the pre-reduction sinter process.The results show that the maximum temperature of sintering flue gas increases from 361°C to 797°C with the carbon mixing ratio gradually increasing from 5wt%to25wt%by adding 3wt%Si O₂and 1wt%Na₂CO₃.The liquid phase increases and the porosity of the pre-reduction sinter is reduced from 20.94%to 0.97%,so that the permeability of the sinter layers becomes worse.The gasification dephosphorization rate is firstly increased from 11.3%to 70%and then decreased to 45%.The tumbler strength of the sinter is increased from 89.73%to 99.99%,and the reduction degree is firstly increased from 19.7%to 48.8%and then reduced to 40.1%.Under the condition of 20wt%carbon mixing ratio and 1wt%Na₂CO₃content,the maximum temperature of sintering flue gas firstly increases from 508°C to 699°C and then decreases to 569°C when the Si O₂content increases from 1wt%to 5wt%.The sintering liquid phase increase and the porosity of the pre-reduction sinter is reduced from 10.59%to 6.56%.The gasification dephosphorization rate is firstly increased from 30%to 70%and then decreased to 27.5%.The tumbler strength is increased from 97.89%to 99.99%,and the reduction degree is reduced from 59.1%to 35.7%.The optimum pre-reduction sintering dephosphorization process parameters were obtained:under the condition of 20wt%carbon mixing ratio,1wt%Na₂CO₃content,and 3%Si O₂content,the maximum gasification dephosphorization rate is 70%,the tumbler strength is 99.78%,and the the reduction degree is 48.8%.