In recent years, the situation of the light-burned magnesium powder steel industry is severe, the cost pressure before iron has increased sharply, the quality of iron ore powder has continuously deteriorated. In order to stabilize the quality of sintered ore further reduce the production cost of iron making, Shougang Jingtang Company finally realized natural magnesium sintering through a series of basic researches. Improve create considerable economic benefits. Light burned magnesium ball
Slightly burned magnesium ball sintering has obvious advantages in magnesium reduction
As the main charge for blast furnaces in the Asia-Pacific region, sintered ore generally accounts for more than 60% of the blast furnace structure. Usually dolomite, serpentine other magnesium-containing fluxes are added to the sintering ingredients to increase the MgO content in the blast furnace slag to improve the fluidity desulfurization ability of the slag adapt to the high Al2O3 mass fraction in the slag.
Sintering as the main source of blast furnace slag MgO, its MgO content is limited by blast furnace slag demand blast furnace operating habits. The MgO content in the blast furnace slag of Japan South Korea is controlled at a level of 3% to 5%, while the domestic content is mostly above 7%. Affected by this, the MgO content of Japan ’s Nippon Steel, South Korea ’s Pohang Gwangyang Hyundai Iron Sinter are 0.7% to 1.2%; while the domestic MgO content of sinters is mostly above 1.6%, the high is even 3.0 %the above. Some researchers even believe that the higher MgO content in sintering is beneficial to improve the quality of sintered ore.
In recent years, a large number of domestic light burned magnesium ball sintering researchers have called for light magnesium burnt sintering to reduce magnesium, Shougang Jingtang has been at the forefront of practice. The project team carried out a series of sintering MgO laboratory studies on the sintering process heat balance calculation, sintering basic characteristic test high-temperature confocal in-situ observation, mineral phase research, sintering cup test, comprehensive charge drop performance test around Shougang Jingtang.
The study found:
Magnesium reduction can help to improve the grade of sintered ore, help to develop high-quality calcium ferrite, improve the reduction of sintered ore. Reducing MgO by 0.5% can increase the TFe content of sintered ore by more than 0.3%. Under the background of the deterioration of imported ore powder, magnesium adjustment shows the value of actively maintaining the grade of sintered ore. The improvement of the grade of sintered ore helps to form more high-quality cemented phases-acicular calcium ferrite, which is beneficial to the improvement of sintered ore index reduction.
Magnesium reduction helps reduce flux heat consumption, thereby increasing the effective heat of sintering. The magnesium-containing flux decomposes consumes heat during sintering, reducing the ratio of magnesium-containing flux helps to save energy improve the quality of sintered ore. The MgO content of the sinter is reduced by 0.5 percentage points, the unit consumption of magnesium-containing flux is reduced by 14kg / t sinter, the decomposition heat consumption of the sintering process is reduced by about 1%, which is equivalent to the increase of the effective heat of the sintering process 1 %, Which is conducive to the improvement of sinter particle size composition.
Magnesium reduction helps to improve the fluidity of the sintering liquid phase enhance the sintering bonding effect. The sintering basic characteristics high-temperature confocal equipment tests show that: after the MgO content of the sintered mixture is reduced 2.3% to 0.3%, the liquid phase fluidity index is increased 0.7 to 1.9; compared with the MgO-containing solution, in-situ observation found that it is The MgO-containing solution has a high liquid phase flow rate. The improved fluidity of the sintered liquid phase enhances the bonding effect is beneficial to the improvement of the sintered particle size composition.
Sintering magnesium reduction with pellets to improve magnesium, on the basis of ensuring the stability of the blast furnace slag system, improves the melting performance of the integrated charge. The droplet performance test showed that after the comprehensive charge structure was changed sintered 1.9% MgO + pellets 0.7% MgO to sintered 1.5% MgO + pellets 1.7% MgO, the droplet range decreased 64 ℃ to 59 ℃, the pressure difference 1910Pa is reduced to 1590Pa, finally the S characteristic value of the integrated charge is reduced 122.2kPa · ℃ to 93.8kPa · ℃.
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