The Cause And Control Of The Ladle Slag Foaming For N-Microalloyed HRB400E

One steelworks has used a new type of nitrogen alloy for producing HRB400E, but in the actual production process, slag foaming is very serious which has influenced the dissolved of adding alloy, the melt of ladle covering flux and deslagging.Through the investigation of field modification manufacturing technique and comparison analysis of N-microalloyed HRB400E ladle slag, finds out the causes of foaming slag. A lab study is made to find the control method of foaming slag, and designs modification agent based on the results of the study, gets the foaming slag under control and industrial test is carried out for testing the actual application effect.The main results are as follows:(1) The main reason for in N-microalloyed HRB400E ladle slag foaming is alloying schedule changed after adopt the new technology, which result in a large variation of the slag composition and changes the physical properties of ladle slag to promote the formation of foaming slag.(2) Study on ladle slag physical properties shows that compositions of slag have obvious effects on the physical properties,and gets the range of slag compositions which has relatively lower viscosity and higher sueface tension is as follow:R=0.8-1.2, MgO=8%～12%, A12O3=6%-8%, CaF2=2%-4%, MO<8%.(3) Through the orthogonal experiment, the slag composition with the weakest foam ability is as follow:R=1.2, A12O3=7%, MgO=12%, CaF2=3%, MO<8.69%and designs modification agent based on the results.(4) Industrial test results show that foaming phenomenon of top slag has been suppressed effectively after top slag modification by using slag modifier.