1. Improve the material of magnesia-chrome bricks in the eye area
The magnesia chrome bricks in the eye area are required to have strong resistance to high temperature, erosion, chemical corrosion, impact and vibration. Therefore, the eye bricks and triangular bricks in the eye area are changed from the original fused 20 magnesia-chrome bricks (DMGe-20) to fused 26 magnesium chrome bricks (DMGe-26).
The content of chromium oxide (Cr2O3) in magnesia-chrome bricks increases, which improves the anti-erosion performance of magnesia-chrome bricks and slows down the washing speed of magnesia-chrome bricks during use. At the same time, the porosity of DMGe-26 magnesia-chrome bricks is significantly reduced, shortening the depth of slag erosion and metal penetration, shortening the hot end metamorphic layer of magnesia-chrome bricks (the length of the metamorphic layer is shortened by about 10mm), reducing the spalling length of refractory bricks, and slowing down the loss rate of tuyere bricks.
2. Strictly control the quality of maintenance
2.1 Mechanical aspects
(1) When repairing the tuyere seat and the tee seat, grind the seat surface to ensure the flatness of the seat surface. Use anti-loosening bolts during installation, and replace the ordinary asbestos pad with aluminum-coated asbestos pad to ensure that there is no air leakage gap at the tuyere seat and the tee seat.
(2) Make a tuyere pipe adjustment template, use the template to select two tuyere pipes as the calibration reference, the tuyere pipe center distance after calibration must meet the requirements of tuyere brick masonry, and weld the tuyere pipe and the tuyere sleeve firmly.
(3) After the tuyere pipe is installed in place, plug the tuyere pipe mouth with a plug, start the GM fan to supply air to the converter, and hold the air pressure to the normal production pressure of the converter (about 0.1MPa), check the air leakage of the bellows and the tuyere connection points, and deal with the air leakage points in time to avoid insufficient air intake due to air leakage, which will cause the tuyere inner pipe and the tuyere area to be washed too quickly.
2.2 Furnace masonry
(1) The eyelet bricks are laid from the middle to both ends. After laying, the front and back of the eyelet bricks are polished to avoid triangular seams in some places.
(2) The square bricks from the eyelet bricks to the upper furnace mouth are laid as required to reduce the height difference between the brick layers in the transition section of the retreat and slow down the loss rate of the transition section furnace bricks.
(3) The mortar in the brick joints is full and uniform, consistent inside and outside, the magnesia chrome brick joints at the interface between the new and old bricks are less than 3mm, the width of the processed bricks is not less than 1/2 of its own width, and the thickness is not less than 2/3 of its own thickness. (4) When laying the upper and lower furnace mouths, steel sheets are welded on the furnace mouth to lock the bricks to avoid the furnace mouth bricks from falling off as a whole when cleaning the furnace mouth during production.
3. Standardize furnace drying operation
Develop furnace drying specifications for minor converter repairs. Use firewood and oil guns to dry the furnace in stages. Strictly control the temperature rise according to the heating curve to ensure that the furnace temperature deviates from the theoretical heating curve by no more than 50°C. Ensure that the thermal expansion of the refractory material meets the material requirements and avoid damage to the refractory bricks caused by large fluctuations in furnace temperature.
4. Optimize production operations
(1) Establish standards for adding cold materials to prevent the furnace temperature from being too high; stabilize and control the matte grade, establish standards for the amount of matte per furnace to avoid large fluctuations in the amount of matte and washing the furnace bricks, and strictly control the output of a single furnace.
(2) Appropriately increase the alkalinity of the slag during slagging, so that magnetic iron is formed in the furnace and adheres to the furnace wall, forming "hanging slag" in the furnace to protect the furnace magnesia chrome bricks.
(3) In converter production, oxygen must be turned off before shaking the furnace to slow down the oxidation loss of the oxygen-enriched air to the tuyere.
