Replacing lime with small particle limestone for steelmaking slag and CO2 resource utilization
The technology for converter injection of limestone powder for slagging steelmaking can improve the effi-ciency of iron dephosphorization and the resource utilization of carbon dioxide.Based on basic experiments of de-phosphorization of small particle limestone slag and lime slag,the slag dephosphorization effect of small particle limestone and lime under the same conditions was compared and analyzed,and the furnace gas benefit using small particle limestone for steelmaking process was calculated.Research has shown that the early stage of using small particle limestone for smelting has a fast dephosphorization rate,and after 5 minutes of smelting,the dephosphoriza-tion efficiency can reach 49.2％,and the dephosphorization rate can reach 0.011 8％/min.When the small particle lime is used for smelting for 5 min,the dephosphorization efficiency is 41.2％,and the dephosphorization rate is 0.009 8％/min.The dephosphorization effect of small particle limestone smelting is equivalent to that of lime smel-ting.The dephosphorization efficiency of small particle limestone and lime at the end of reaction is 87.50％and 89.08％,respectively,and the dephosphorization rate of small particle limestone and lime at the end of smelting is both more than 85％.Both small particle lime and limestone can achieve homogenization of slag,with a uniform dis-tribution of elements in the slag.The mass fraction of P element in limestone dephosphorization slag and lime de-phosphorization slag is 9％and 8％,respectively.When using limestone for slagging steelmaking,the P element content in slag in the early stage is higher.When using small particle limestone for slagging steelmaking,the carbon dioxide produced by limestone decomposition can react with various elements in molten iron,and its utilization rate can reach 40％.The carbon dioxide produced by the limestone decomposition replaces some oxygen to participate in the oxidation reaction,generating carbon monoxide.The carbon monoxide in the gain furnace gas is about 6.5 m3 per ton of steel.The research results provide a theoretical basis for the industrial application of converter injection limestone powder slag making and steelmaking,and promote the further development of green metallurgy.
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