Light burned magnesia powder is sintered to reduce magnesium, with more beautiful benefits

In recent years, the situation of light burned magnesia iron and steel industry is severe, the cost pressure before iron production increases sharply, and the quality of iron ore powder continues to deteriorate. In order to stabilize the sinter quality and further reduce the ironmaking production cost, Steel Jingtang Company, through a series of basic research, finally realized natural magnesium sintering. The sinter grade, strength, particle size, metallurgical performance and droplet performance were obtained, and considerable economic benefits were achieved. Building material grade magnesium oxide

The advantages of light burned magnesium pellets in reducing magnesium content are obvious

As the main burden of blast furnace in Asia Pacific region, sinter generally accounts for 60% of the blast furnace structure. Usually, magnesium containing fluxes such as dolomite and serpentine are added in the sintering ingredients to increase the MgO content in the blast furnace slag, which is suitable for the high Al2O3 mass fraction in the slag with the fluidity and desulfurization capacity of the slag.

Sintering is the main source of MgO in blast furnace slag, and its MgO content is limited by the demand of blast furnace slag and the operation habit of blast furnace. The MgO content in blast furnace slag in Japan and South Korea is controlled at 3%~5%, while that in China is mostly 7. Under this influence, the MgO content of sinters from Nippon Steel (Japan), Pohang Guangyang (South Korea) and Hyundai Iron making Co., Ltd. is 0.7%~1.2%; However, the MgO content of domestic sinters is mostly 1.6, even 3.0. Some researchers even believe that higher MgO content in sintering is beneficial to the improvement of sinter quality.

In recent years, a large number of domestic researchers on light burned magnesium ball sintering have called for magnesium reduction in light burned magnesium ball sintering, and Steel Jingtang is in the forefront of practice. The project team has carried out a series of laboratory studies on reducing MgO in sintering around Steel Jingtang, including calculation of heat balance in sintering process, testing of basic sintering characteristics, in-situ observation of high temperature confocal, mineralogy research, sintering cup test, and comprehensive furnace charge droplet performance test.

Reducing magnesium is helpful to improve sinter grade, develop high-quality calcium ferrite and improve sinter reducibility. Reducing 0.5% MgO can increase the TFe content of sinter by 0.3; In the context of the deterioration of the ore powder, magnesium regulation shows the value of actively maintaining the sinter grade. The increase of sinter grade will help to form more high-quality bonding phase - acicular calcium ferrite, which is beneficial to sinter index and reducibility.

Reducing magnesium is helpful to reduce heat consumption of flux, thus increasing effective heat of sintering. The decomposition heat consumption of magnesium containing flux in the sintering process, reducing the ratio of magnesium containing flux is helpful to energy saving and sinter quality. The MgO content of sinter is reduced by 0.5 percentage points, the unit consumption of magnesium containing flux is reduced by 14kg/t of sinter, and the decomposition heat consumption in the sintering process is reduced by about 1%, which is equivalent to that the effective heat in the sintering process is increased by 1% under the condition of sintering heat loss, which is conducive to the size composition of sinter.

Reducing magnesium is helpful to the fluidity of sintering liquid phase and the bonding effect of sintering. The basic sintering characteristics and high temperature confocal equipment tests show that the liquid-phase fluidity index increases from 0.7 to 1.9 after the MgO content of sintering mixture decreases from 2.3% to 0.3%; Compared with the scheme containing MgO, the liquid phase flow velocity of the scheme containing MgO was observed in situ. The fluidity of sintering liquid phase enhances the bonding effect and is beneficial to the size composition of sinter.

Reducing magnesium content by sintering and increasing magnesium content by pelletizing can improve the molten drop performance of comprehensive burden on the basis of stable slag system of blast furnace. The droplet performance test shows that after the composite charge structure is changed from 1.9% MgO+pellet 0.7% MgO to 1.5% MgO+pellet 1.7% MgO, the droplet range decreases 59 ℃ from 64 ℃, the differential pressure decreases 1590 Pa from 1910 Pa, and finally the S characteristic value of the composite charge decreases 93.8 kPa · ℃ from 122.2 kPa · ℃.