Study On Thermodynamics Of Dephosphorization By Slag Gasification In Dephosphorization Converter

To solve the problem that phosphorus content of dephosphorization converter slag via duplex smelting is too high to be directly returned to the converter for utilization,the analysis was made on feasibility and influencing factors of gasification dephosphorization reaction at a low temperature by combining theoretical analysis with experiments as well as using Factsage and other software.Following conclusions are obtained:The calculation and analysis of thermodynamics show that gasification dephosphorization reaction can occur at actual low temperatures（1573K～1733K）and with P2 as main gas product;when dephosphorization slag is reduced with coke,P₂O₅ is reduced before Fe O.Carbothermal gasification dephosphorization test shows that gasification dephosphorization rate increases with the increase of temperature or with the decrease of alkalinity;in 10%<Fe O%<30%,gasification dephosphorization rate increases first and then decreases with the increase of Fe O,and the highest gasification dephosphorization rate is 42.3% at Fe O=25%;when nitrogen flow rate is 40L/h～120L/h,gasification dephosphorization rate increases first and then decreases;with the increase of temperature and alkalinity,the reduction rate of Fe O increases;at temperature of 1733 K and alkalinity of 2.2,the highest reduction rates are 62.3% and 44.86% respectively;the effect of nitrogen flow rate on Fe O reduction is not obvious.Comparing the phases of dephosphorization slag before and after gasification dephosphorization,it shows that the ore phases of dephosphorization slag mainly include calcium ferrite olivine,dicalcium silicate,RO phrase,and contain a bit tricalcium phosphate.After carbothermal reduction,the contents of Fe O phase and P₂O₅ phase decrease.Study on migration law of phosphorus before and after gasification dephosphorization shows that phosphorus mainly exists in the silicon-calcium enrichment region,namely Dicalcium silicate phase,and gasification dephosphorization reaction mainly occurs in phosphorus-enriched dicalcium silicate phase.Figure 47;Table 22;References 84...