No 3 blast furnace of Baosteel Co Ltd Iron making Plant created good records for smelting of hot metal for grain oriented silicon steel. Under the conditions of 5 simultaneous, the comprehensive qualifying ratio of hot metal composition, temperature and burden from September last year to January this year has reached above 75% for 5 months consecutively, among which the highest was 92.6% in December last year, providing quality raw material guarantee for Baosteel's production of high grade silicon steel. It proves that Baosteel's smelting of hot metal for grain-oriented silicon steel has reached international leading level.
Grain-oriented silicon steel is honored as the art of steel industry, and its manufacturing level represents a steelmaker comprehensive competitiveness. Since silicon steel has extremely high requirements for composition control, it directly affects the continuous production of silicon steel whether the composition and temperature of hot metal are appropriate or not. Ever since Baosteel Co Ltd produced the first coil of grain-oriented silicon steel, No.3 blast furnace has been smelting the hot metal according to 3 simultaneous of composition, burden and temperature of hot metal.
As Baosteel's silicon steel production marches toward the high end, the requirements for hot metal for silicon steel become more stringent. At the end of 2008, on the basis of the existing demanganizing, Iron-making Plant put forward the requirements for dual removal to upgrade 3 simultaneous into 5 simultaneous.
Since different steel grades have different standards, the hot metal composition, burden and hot metal temperature restrict each other it is extremely difficult to satisfy the 5 conditions at the same time. Therefore, Iron-making Plant set up a six sigma task force participated by the technical backbones of the plant and workshops and coordinated with the relevant departments including Steel-making Plant and Manufacture Department to carry out brainstorming in view of the factors affecting the comprehensive qualifying ratio of grain-oriented silicon steel, analyze the correlation that affects the quality of hot metal for grain-oriented silicon steel, determine the quantifying relationship of each affecting factor and considerably reduce the fluctuating range of each control parameter.
Through sustained exploration, the standards for initial hot metal composition control, charging amount, iron receiving time and quantifying operation for different silicon steel have been formulated. With a view to increase the correctness of the burden for different steel grade, the task force advised the lean control mode of "stop watch + iron strand speed. Chief foreman responsibility system is implemented in operation, excellent shift is selected for lean operation, which is gradually extended in an all-round way.
