The Influence of liquid residence time in ladle (<135 min ~ >240 min)

tapping temperature (<1 640 ℃ - > 1 650 ℃)

temperature of liquid in ladle at casting station (<1 540 ℃～ >1 580 ℃)

Mn content in steel (< 0. 5% - >1. 3%) for steelmaking the low carbon steels such as LZ20Mn2

20MnV6 and 20MnTiB on free-opening rate of a 70-t ladle is statistically analyzed. It is obtained with prolonging residence time

increasing tapping temperature and temperature of liquid in ladle at casting station

and increasing Mn content in steel the ladle free-opening rate may decrease from 98. 8% to 76. 8%. With improving bake of packing sand for ladle sliding gate

in time clearing residual steel and slag in ladle

cleaning up nozzle

and decreasing average residence time of liquid in ladle to 160 min from original 180 min

the ladle free-opening rate increases to 97. 3% from original 88. 4%.