Practical Study On Reducing The Comprehensive Coke Ratio Of 1780 Blast Furnace

In recent years,with increasing production capacity of domestic iron and steel,steel situation has become more severe,which steel price has been falling,but the price of raw fuel has remained high,causing profit margin has been gradually reduced.Therefore,reducing the cost of iron and steel by the means of controlling suitable comprehensive coke ratio has become the most important mean for steel companies.Based on a large number of relevant references,the paper analyzes the practice of reducing the comprehensive coke ratio of 1#1780 blast furnace.The ratio of raw fuel,current measures,upper and lower parts of the air supply system,and adjustment and limiting factors of the coal injection ratio and corresponding measures have been deeply analyzed.Under the conditions of this paper,the main conclusions are as follows.The coke evaluation system is used to compare furnace coke with different ratios.The coke with high scoring grade and small furnace fluctuation is selected.It is found that the Yuwang coke and the Xuyang third grade coke are beneficial to produce iron,which favors that comprehensive coke ratio is reduced from 529.3kg/t to 481.4kg/t.If the frequency of controlling kerosene ratio is less than 2 times per month and heating value of pulverized coal is above 7300cal,comprehensive coke ratio is reduced from 536kg/t to 520.04kg/t.By controlling particle size of furnace ore,monitoring granulation furnace level,increasing sinter sieve from 5mm to 6.5mm,and reducing powder content in the furnace,comprehensive coke ratio is reduced from 521.32 kg/t to 471.44 kg/t when content of Al2O3 in the slag is 15?17%.Under normal condition of blast furnace,air supply temperature is above 1240?,air supply volume is 3350?3550m3/min,and oxygen enrichment rate is 3.5?4.2%,tuyere blowpipe is gradually extended from 450mm to 530mm,and tuyere diameter is 120mm replaced by 110mm.Based on the above situation,by reducing tuyere area to 0.2574m2,conducting skin monitoring of hot air pipe at the three mouths,and grouting hot air pipe during the period of half-year maintenance,comprehensive coke ratio is reduced from 522.3kg/t to 491.2kg/t,the batch is increased from 42t to 45t and material line is reduced from 1.9m to 1.7m.At the same time,distribution angle of mine and focal and content of CO2 in the gas is real time monitored,so that comprehensive coke ratio is reduced from 535.7kg/t to 514.7kg/t.When physical heat of hot metal is controlled between 1480? and 1510?,silicon content of pig iron is controlled between 0.25%and 0.45%,manganese content of pig iron is controlled below 0.4%,and alkalinity is controlled between 1.08 and 1.15,comprehensive coke ratio is reduced from 535.7kg/t to 502.3kg/t.