Study On Prescription Optimization And Metallurgic Characteristic Of Refining Slag In LF Furnace Of Chongqing I&S Co

Slag refining is essential to realize various refining functions of LF furnace, which is one of the crucial technologies for producing top grade quality steel in Chongqing I&S Co.. A_t present, to various steel, using only one slag will limite the advantages of LF furnace in producing top grade steel, the prescription of slag charge refining is too simplex to produce various steel.This paper optimum designed 29 sorts of slag used in LF, (9 for aluminium-containg steel and 20 the others) according to the situation and requirements of LF furnace in Chongqing I&S Co.. Compared with the slag under used, the 29 newer have following traits:1) the basicity of slag has been improved a lot;2) refining effect is better;3) concentration of M_gO in slag charge increases ,as a result , the life of ladle has been prolonged; 4) the concentration of Al2O3 in slag charge has been adjusted appropriately, which can control the content of [Al]; 5) adding proper amount of magnesite in blister can stabilize the foam ability of slag charge.B_y orthogonal design, the nature of typical slag charge in these 29 new designed slag was rounded tested and analysed. The key prescription of refining slag charge in LF for controlling the content of Al in steel is that: A₁ M₁,A₁ M₂,A₂ M₃,A₂ M₄,A₃ M₁,A₃ M₂,A₄ M₃,A₄ M₄,A₅ M₃; and the one for steel containing Al is that: B₁ L₁,B₁ L₂,B₂ L₁,B₂ L₂,B₃ L₁,B₃ L₂,B₁ L₃,B₂ L₃,B₃ L₃.B_y using thermal analyser and inducttion furnace, the metallurgic nature and desulfurating ability of these 29 new designed slags were tested and analyzed systematically. The results indicated that , the melting point ,formability, viscosity, basicity, interfacial force and desulfurating ability of slag charge are all in the required range for refining in LF, and are optimally matched , meeting the requirements of production in LF very well.In the tests on LF production of Chongqing I&S Co., the time for the electric arc of these new designed slag charges begin to submerge are all less than 3 minutes .The processing property is stable. Desulfurating rate of steel containing Al is above 60%, and desulfurating rate of steel controlling Al `s content is around 50%. The contents of almost non-metallic inclusion are around 0.0006%, the highest is 0.008%, and the lowest is 0.002%. The increment amount of H is less than 0.8ppm for steel containing Al, and is less than 1.0ppm for steel controlling Al `s content. The increment amount of N is a little higher, for both steels around 6⁹ppm.The passing detection rate is 100%. A_fter using the new designed slag of LF, the life of ladle slag line achieves to an average age of 45 times, much more than 22 times of that before. According to these test results, a conclusion that the effects of overall tests on slag charge of LF is significant and can qualify the productive requirements of Chongqing I&S Co., can be made .Integrate the metallurgy nature and productive tests effect, during the formal productive process of Chongqing I&S Co., the recommended refining slag is: A2M3,A5M3,A3M4(for controlling -Al content steel );B1L2(for containing -Al steel).