Introduction of Light burned Magnesium Powder in China

The introduction of light burned magnesia powder in China. In recent years, the situation of light burned iron and steel industry is severe, the cost pressure before iron is increasing sharply, and the quality of iron ore powder is deteriorating. In order to stabilize the sinter quality and further reduce the ironmaking production cost, Z finally realized natural magnesium sintering, and the sinter grade, strength, particle size, metallurgical properties and droplet properties were improved, creating considerable economic benefits.

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 more than 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, so as to improve the fluidity and desulfurization capacity of the slag and adapt to the high Al2O3 mass fraction in 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 more than 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 more than 1.6%, even more than 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 in light burned magnesium ball sintering have called for magnesium reduction in light burned magnesium ball sintering, and Jingtang of Shougang is in the forefront of practice. The project team has carried out a series of laboratory studies on reducing MgO in sintering around Shougang 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.

Research findings:

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 more than 0.3%; In the context of the deterioration of imported ore fines, magnesium regulation shows the value of actively maintaining the sinter grade. The increase of sinter grade is conducive to the formation of more high-quality bonding phase - acicular calcium ferrite, which is beneficial to the improvement of 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 will help to save energy and improve the 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% when the sintering heat loss is certain, which is conducive to the improvement of the particle size composition of sinter.

Reducing magnesium is helpful to improve the fluidity of sintering liquid phase and enhance the sintering bonding effect. The basic sintering characteristics and high temperature confocal equipment tests show that the liquid-phase fluidity index increases from 0.7 to 1.9 when the MgO content of sintering mixture decreases from 2.3% to 0.3%; Compared with the scheme containing MgO, the scheme without MgO has a high liquid phase flow velocity of Z. The improvement of the fluidity of the sintering liquid phase enhances the bonding effect and is beneficial to the improvement of the sinter particle size composition.

The dropping of magnesium by sintering and the increasing of magnesium by pelletizing can improve the droplet performance of comprehensive burden on the basis of ensuring the stability of blast furnace slag system. The droplet performance test shows that after the comprehensive charge structure changes from 1.9% MgO+pellet 0.7% MgO to 1.5% MgO+pellet 1.7% MgO, the droplet range decreases from 64 ℃ to 59 ℃, and the large pressure difference Z decreases from 1910Pa to 1590Pa. Z finally reduces the S characteristic value of the comprehensive charge from 122.2kPa · ℃ to 93.8kPa · ℃.