Light-burned magnesium powder sintered to reduce magnesium, and the benefits are more beautiful

In recent years, the light-burned magnesium powder iron and steel industry has faced severe situation, the cost pressure before iron has increased sharply, and the quality of iron ore powder has been continuously deteriorated. In order to stabilize the quality of sinter ore and further reduce the production cost of ironmaking, the company has finally achieved natural magnesium sintering after a series of basic researches. economic benefits. Lightly burnt powder

The advantages of light-burned magnesium ball sintering to reduce magnesium are obvious

As the main charge for blast furnaces in the Asia-Pacific region, sinter generally accounts for more than 60% of the blast furnace structure. Usually dolomite, serpentine and other magnesium-containing fluxes are added to the sintering ingredients to increase the MgO content in the blast furnace slag, so as to improve the fluidity and desulfurization ability 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 blast furnace slag demand and blast furnace operating habits. The content of MgO in blast furnace slag in Japan and South Korea is controlled at the level of 3% to 5%, while most domestic ones are above 7%. Affected by this, the MgO content of Japan's Nippon Steel, South Korea's Pohang Gwangyang and Hyundai Steel's sinter ore is at the level of 0.7%~1.2%; while the MgO content of domestic sinter ore is mostly above 1.6%, and the high content is even 3.0%. %above. 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 light-burned magnesium ball sintering researchers have called for light-burned magnesium ball sintering to reduce magnesium, and Shougang Jingtang has been at the forefront of practice. The project team carried out a series of sintering MgO-reducing laboratory researches around Shougang Jingtang, including heat balance calculation in sintering process, sintering basic characteristic test, high-temperature confocal in-situ observation, mineral phase research, sintering cup test, and comprehensive charge droplet performance test.

The study found:

Magnesium reduction helps to improve the grade of sinter, help to develop high-quality calcium ferrite, and improve the reducibility of sinter. Reducing MgO by 0.5% can increase the TFe content of sinter by more than 0.3%; under the background of the deterioration of imported ore powder, magnesium adjustment shows the value of actively maintaining the sinter grade. The improvement of the sinter grade will help to form more high-quality binder phase—acicular calcium ferrite, which is beneficial to the improvement of sinter index and reducibility.

Magnesium reduction helps to reduce the heat consumption of the flux, thereby increasing the effective heat of sintering. Magnesium-containing flux decomposes and consumes heat during the sintering process, and reducing the ratio of magnesium-containing flux helps to save energy and improve sinter quality. The MgO content of sintered ore is reduced by 0.5%, the unit consumption of magnesium-containing flux is reduced by 14kg/t sintered ore, and the heat consumption of decomposition in the sintering process is reduced by about 1%, which is equivalent to an increase in the effective heat of the sintering process by 1 under the condition of a certain sintering heat loss. %, which is beneficial to the improvement of sinter particle size composition.

Magnesium reduction helps to improve the fluidity of the sintered liquid phase and enhance the sintering bonding effect. The basic characteristics of sintering and the test of high temperature confocal equipment show that: after the MgO content of the sintered mixture is reduced from 2.3% to 0.3%, the liquid phase fluidity index increases from 0.7 to 1.9; The MgO-containing protocol has a high liquid phase flow velocity. The improvement of the fluidity of the sintered liquid phase enhances the bonding effect, which is beneficial to the improvement of the particle size composition of the sintered ore.

The combination of sintering magnesium reduction and pelletizing magnesium extraction improves the droplet performance of the comprehensive charge on the basis of ensuring the stability of the blast furnace slag system. The droplet performance test shows that after the comprehensive charge structure is changed from sinter 1.9%MgO + pellet 0.7%MgO to sinter 1.5%MgO + pellet 1.7%MgO, the droplet range is reduced from 64 ℃ to 59 ℃, and the pressure difference is large. From 1910Pa to 1590Pa, the S characteristic value of the integrated charge was reduced from 122.2kPa·℃ to 93.8kPa·℃ finally.