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Yudenkov Ievgen

Faculty: Physically-metallurgical
Speciality: Metallurgy of ferrous metals

Theme of master's work:

Research slag foaming technology influence of nitrogen behavior during operation in EAF (electric arc furnace)

Scientific adviser: Korzun Ievgen Ph.D

Abstract

      Nitrogen is an undesirable component in many steelsdegree. There by eloboration of decrasing methods of N is very urgent in semiproduct producing and subsequent processing in LF (ladle furnace) and teeming. In order to semiproduct producing intensification in EAF: carbon and carboncontent materials blowing ahd high power arc. There is tendency to increasing average content of nitrogen in metal less than 0,010%. Today task is producing semiprodukt with average content of nitrogen less than 0,004%, and in the future up to 10 ppm.
      In this work is studying slag foaming technology influence nitrogen content in semiprodukt, which producing in high power EAF melted in super-power DSP.

      Nitrogen has 2 main an entering way steel:

- a charge is a crow-bar and his substitutes, slag-formings additions, coke;

- nitrogen which is taken in from an atmosphere (or retires) in the flow of melting.

      Table: Nitrogen content of feed materials used in EAF steelmaking

Feed Material	Nitrogen Content, ppm
Scrap	30-120
HBI/DRI	20-30
Coke	5000-10000
Oxygen	30-200
СаО	400
Liquid iron from the BF	60
Cold pig iron (CPI)	20-30
SiCa	1900

      As be obvious from a table most influence on the concentration of nitrogen in steel renders uglerodsoderzhaschiy material (coke), that making the foam of slag.

      While semiprodukt smelting for crude steel in EAF-2 of EAF shop of «DEMZ» were controlled nitrogen content in fluent metall sample, which has took away from the furnace in order to technological instruction: first sample - after scrap was melted, second sample - before tapping. Analysis of nitrogen content was obtained on Leko Ts300.

      Changing the nitrogen content in the metal during the oxidation period of in the EAF, when occurs intensive foaming slag, in Figure 1. As can be seen from this figure, for the oxidation period there is a general tendency of the reduction of nitrogen content in the metal during smelting. There are a number of melting in which the nitrogen content by the end of melting has increased. To analyze the reasons for the vector directionality of change nitrogen content source data were presented in the form of dependence magnitude of change nitrogen content during the oxidation period, of the ratio value mass of carbon additives, made during a oxidation period in the furnace, with slag foaming, the mass of oxygen injected into the same time in the furnace (figure 2).

Picture 1 - Change of maintenance of nitrogen in semiprodukt in the flow of oxidizing period of melting EAF.

Picture 2 - Influence of correlation of the masses of carbon to mass of oxygen, brought in during an oxidizing period in stove, on the change of maintenance of nitrogen in semiprodukt.

       LIST OF THE UTILLIZED LITERATURE

1. Морозов А.Н. Водород и азот в стали. - М.: Металлургия, 1968. - 284с
2. Pehlke R.D., Elliott J.F. Solubility of Nitrogen in Liquid Iron Alloys. Thermodinamics // Trans AIME. - 1960. - 218, №6. - Р.1088-1101.
3. Molinero J., Laraudogoitia J.J., Bilbao E. New technologies for low nitrogen EAF steelmaking.// 6th Eur. Elec. Stelmak. Conf., Dusseldorf, June 13-15, 1999: Proc.- Dusseldorf, 1999. C.51-57

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